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Commit | Line | Data |
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ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
ed3d261b JP |
29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
30 | ||
ddbcc7e8 | 31 | #include <linux/cgroup.h> |
2ce9738b | 32 | #include <linux/cred.h> |
c6d57f33 | 33 | #include <linux/ctype.h> |
ddbcc7e8 | 34 | #include <linux/errno.h> |
2ce9738b | 35 | #include <linux/init_task.h> |
ddbcc7e8 PM |
36 | #include <linux/kernel.h> |
37 | #include <linux/list.h> | |
c9482a5b | 38 | #include <linux/magic.h> |
ddbcc7e8 PM |
39 | #include <linux/mm.h> |
40 | #include <linux/mutex.h> | |
41 | #include <linux/mount.h> | |
42 | #include <linux/pagemap.h> | |
a424316c | 43 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
44 | #include <linux/rcupdate.h> |
45 | #include <linux/sched.h> | |
ddbcc7e8 | 46 | #include <linux/slab.h> |
ddbcc7e8 | 47 | #include <linux/spinlock.h> |
96d365e0 | 48 | #include <linux/rwsem.h> |
1ed13287 | 49 | #include <linux/percpu-rwsem.h> |
ddbcc7e8 | 50 | #include <linux/string.h> |
bbcb81d0 | 51 | #include <linux/sort.h> |
81a6a5cd | 52 | #include <linux/kmod.h> |
846c7bb0 BS |
53 | #include <linux/delayacct.h> |
54 | #include <linux/cgroupstats.h> | |
0ac801fe | 55 | #include <linux/hashtable.h> |
096b7fe0 | 56 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 57 | #include <linux/idr.h> |
d1d9fd33 | 58 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 59 | #include <linux/kthread.h> |
776f02fa | 60 | #include <linux/delay.h> |
846c7bb0 | 61 | |
60063497 | 62 | #include <linux/atomic.h> |
ddbcc7e8 | 63 | |
b1a21367 TH |
64 | /* |
65 | * pidlists linger the following amount before being destroyed. The goal | |
66 | * is avoiding frequent destruction in the middle of consecutive read calls | |
67 | * Expiring in the middle is a performance problem not a correctness one. | |
68 | * 1 sec should be enough. | |
69 | */ | |
70 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
71 | ||
8d7e6fb0 TH |
72 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
73 | MAX_CFTYPE_NAME + 2) | |
74 | ||
e25e2cbb TH |
75 | /* |
76 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
77 | * hierarchy must be performed while holding it. | |
78 | * | |
0e1d768f TH |
79 | * css_set_rwsem protects task->cgroups pointer, the list of css_set |
80 | * objects, and the chain of tasks off each css_set. | |
e25e2cbb | 81 | * |
0e1d768f TH |
82 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
83 | * cgroup.h can use them for lockdep annotations. | |
e25e2cbb | 84 | */ |
2219449a TH |
85 | #ifdef CONFIG_PROVE_RCU |
86 | DEFINE_MUTEX(cgroup_mutex); | |
0e1d768f TH |
87 | DECLARE_RWSEM(css_set_rwsem); |
88 | EXPORT_SYMBOL_GPL(cgroup_mutex); | |
89 | EXPORT_SYMBOL_GPL(css_set_rwsem); | |
2219449a | 90 | #else |
81a6a5cd | 91 | static DEFINE_MUTEX(cgroup_mutex); |
0e1d768f | 92 | static DECLARE_RWSEM(css_set_rwsem); |
2219449a TH |
93 | #endif |
94 | ||
6fa4918d | 95 | /* |
15a4c835 TH |
96 | * Protects cgroup_idr and css_idr so that IDs can be released without |
97 | * grabbing cgroup_mutex. | |
6fa4918d TH |
98 | */ |
99 | static DEFINE_SPINLOCK(cgroup_idr_lock); | |
100 | ||
69e943b7 TH |
101 | /* |
102 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
103 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
104 | */ | |
105 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
81a6a5cd | 106 | |
1ed13287 TH |
107 | struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
108 | ||
8353da1f | 109 | #define cgroup_assert_mutex_or_rcu_locked() \ |
f78f5b90 PM |
110 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
111 | !lockdep_is_held(&cgroup_mutex), \ | |
8353da1f | 112 | "cgroup_mutex or RCU read lock required"); |
780cd8b3 | 113 | |
e5fca243 TH |
114 | /* |
115 | * cgroup destruction makes heavy use of work items and there can be a lot | |
116 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
117 | * destruction work items don't end up filling up max_active of system_wq | |
118 | * which may lead to deadlock. | |
119 | */ | |
120 | static struct workqueue_struct *cgroup_destroy_wq; | |
121 | ||
b1a21367 TH |
122 | /* |
123 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
124 | * separate workqueue as flush domain. | |
125 | */ | |
126 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
127 | ||
3ed80a62 | 128 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 129 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 130 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
131 | #include <linux/cgroup_subsys.h> |
132 | }; | |
073219e9 TH |
133 | #undef SUBSYS |
134 | ||
135 | /* array of cgroup subsystem names */ | |
136 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
137 | static const char *cgroup_subsys_name[] = { | |
ddbcc7e8 PM |
138 | #include <linux/cgroup_subsys.h> |
139 | }; | |
073219e9 | 140 | #undef SUBSYS |
ddbcc7e8 | 141 | |
49d1dc4b TH |
142 | /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
143 | #define SUBSYS(_x) \ | |
144 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ | |
145 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ | |
146 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ | |
147 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); | |
148 | #include <linux/cgroup_subsys.h> | |
149 | #undef SUBSYS | |
150 | ||
151 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, | |
152 | static struct static_key_true *cgroup_subsys_enabled_key[] = { | |
153 | #include <linux/cgroup_subsys.h> | |
154 | }; | |
155 | #undef SUBSYS | |
156 | ||
157 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, | |
158 | static struct static_key_true *cgroup_subsys_on_dfl_key[] = { | |
159 | #include <linux/cgroup_subsys.h> | |
160 | }; | |
161 | #undef SUBSYS | |
162 | ||
ddbcc7e8 | 163 | /* |
3dd06ffa | 164 | * The default hierarchy, reserved for the subsystems that are otherwise |
9871bf95 TH |
165 | * unattached - it never has more than a single cgroup, and all tasks are |
166 | * part of that cgroup. | |
ddbcc7e8 | 167 | */ |
a2dd4247 | 168 | struct cgroup_root cgrp_dfl_root; |
d0ec4230 | 169 | EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
9871bf95 | 170 | |
a2dd4247 TH |
171 | /* |
172 | * The default hierarchy always exists but is hidden until mounted for the | |
173 | * first time. This is for backward compatibility. | |
174 | */ | |
175 | static bool cgrp_dfl_root_visible; | |
ddbcc7e8 | 176 | |
a8ddc821 TH |
177 | /* |
178 | * Set by the boot param of the same name and makes subsystems with NULL | |
179 | * ->dfl_files to use ->legacy_files on the default hierarchy. | |
180 | */ | |
181 | static bool cgroup_legacy_files_on_dfl; | |
182 | ||
5533e011 | 183 | /* some controllers are not supported in the default hierarchy */ |
8ab456ac | 184 | static unsigned long cgrp_dfl_root_inhibit_ss_mask; |
5533e011 | 185 | |
ddbcc7e8 PM |
186 | /* The list of hierarchy roots */ |
187 | ||
9871bf95 TH |
188 | static LIST_HEAD(cgroup_roots); |
189 | static int cgroup_root_count; | |
ddbcc7e8 | 190 | |
3417ae1f | 191 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 192 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 193 | |
794611a1 | 194 | /* |
0cb51d71 TH |
195 | * Assign a monotonically increasing serial number to csses. It guarantees |
196 | * cgroups with bigger numbers are newer than those with smaller numbers. | |
197 | * Also, as csses are always appended to the parent's ->children list, it | |
198 | * guarantees that sibling csses are always sorted in the ascending serial | |
199 | * number order on the list. Protected by cgroup_mutex. | |
794611a1 | 200 | */ |
0cb51d71 | 201 | static u64 css_serial_nr_next = 1; |
794611a1 | 202 | |
cb4a3167 AS |
203 | /* |
204 | * These bitmask flags indicate whether tasks in the fork and exit paths have | |
205 | * fork/exit handlers to call. This avoids us having to do extra work in the | |
206 | * fork/exit path to check which subsystems have fork/exit callbacks. | |
ddbcc7e8 | 207 | */ |
cb4a3167 AS |
208 | static unsigned long have_fork_callback __read_mostly; |
209 | static unsigned long have_exit_callback __read_mostly; | |
ddbcc7e8 | 210 | |
7e47682e AS |
211 | /* Ditto for the can_fork callback. */ |
212 | static unsigned long have_canfork_callback __read_mostly; | |
213 | ||
a14c6874 TH |
214 | static struct cftype cgroup_dfl_base_files[]; |
215 | static struct cftype cgroup_legacy_base_files[]; | |
628f7cd4 | 216 | |
3dd06ffa | 217 | static int rebind_subsystems(struct cgroup_root *dst_root, |
8ab456ac | 218 | unsigned long ss_mask); |
42809dd4 | 219 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
f63070d3 TH |
220 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
221 | bool visible); | |
9d755d33 | 222 | static void css_release(struct percpu_ref *ref); |
f8f22e53 | 223 | static void kill_css(struct cgroup_subsys_state *css); |
2bb566cb TH |
224 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
225 | bool is_add); | |
42809dd4 | 226 | |
fc5ed1e9 TH |
227 | /** |
228 | * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID | |
229 | * @ssid: subsys ID of interest | |
230 | * | |
231 | * cgroup_subsys_enabled() can only be used with literal subsys names which | |
232 | * is fine for individual subsystems but unsuitable for cgroup core. This | |
233 | * is slower static_key_enabled() based test indexed by @ssid. | |
234 | */ | |
235 | static bool cgroup_ssid_enabled(int ssid) | |
236 | { | |
237 | return static_key_enabled(cgroup_subsys_enabled_key[ssid]); | |
238 | } | |
239 | ||
9e10a130 TH |
240 | /** |
241 | * cgroup_on_dfl - test whether a cgroup is on the default hierarchy | |
242 | * @cgrp: the cgroup of interest | |
243 | * | |
244 | * The default hierarchy is the v2 interface of cgroup and this function | |
245 | * can be used to test whether a cgroup is on the default hierarchy for | |
246 | * cases where a subsystem should behave differnetly depending on the | |
247 | * interface version. | |
248 | * | |
249 | * The set of behaviors which change on the default hierarchy are still | |
250 | * being determined and the mount option is prefixed with __DEVEL__. | |
251 | * | |
252 | * List of changed behaviors: | |
253 | * | |
254 | * - Mount options "noprefix", "xattr", "clone_children", "release_agent" | |
255 | * and "name" are disallowed. | |
256 | * | |
257 | * - When mounting an existing superblock, mount options should match. | |
258 | * | |
259 | * - Remount is disallowed. | |
260 | * | |
261 | * - rename(2) is disallowed. | |
262 | * | |
263 | * - "tasks" is removed. Everything should be at process granularity. Use | |
264 | * "cgroup.procs" instead. | |
265 | * | |
266 | * - "cgroup.procs" is not sorted. pids will be unique unless they got | |
267 | * recycled inbetween reads. | |
268 | * | |
269 | * - "release_agent" and "notify_on_release" are removed. Replacement | |
270 | * notification mechanism will be implemented. | |
271 | * | |
272 | * - "cgroup.clone_children" is removed. | |
273 | * | |
274 | * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup | |
275 | * and its descendants contain no task; otherwise, 1. The file also | |
276 | * generates kernfs notification which can be monitored through poll and | |
277 | * [di]notify when the value of the file changes. | |
278 | * | |
279 | * - cpuset: tasks will be kept in empty cpusets when hotplug happens and | |
280 | * take masks of ancestors with non-empty cpus/mems, instead of being | |
281 | * moved to an ancestor. | |
282 | * | |
283 | * - cpuset: a task can be moved into an empty cpuset, and again it takes | |
284 | * masks of ancestors. | |
285 | * | |
286 | * - memcg: use_hierarchy is on by default and the cgroup file for the flag | |
287 | * is not created. | |
288 | * | |
289 | * - blkcg: blk-throttle becomes properly hierarchical. | |
290 | * | |
291 | * - debug: disallowed on the default hierarchy. | |
292 | */ | |
293 | static bool cgroup_on_dfl(const struct cgroup *cgrp) | |
294 | { | |
295 | return cgrp->root == &cgrp_dfl_root; | |
296 | } | |
297 | ||
6fa4918d TH |
298 | /* IDR wrappers which synchronize using cgroup_idr_lock */ |
299 | static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, | |
300 | gfp_t gfp_mask) | |
301 | { | |
302 | int ret; | |
303 | ||
304 | idr_preload(gfp_mask); | |
54504e97 | 305 | spin_lock_bh(&cgroup_idr_lock); |
cf780b7d | 306 | ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_WAIT); |
54504e97 | 307 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
308 | idr_preload_end(); |
309 | return ret; | |
310 | } | |
311 | ||
312 | static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) | |
313 | { | |
314 | void *ret; | |
315 | ||
54504e97 | 316 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 317 | ret = idr_replace(idr, ptr, id); |
54504e97 | 318 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
319 | return ret; |
320 | } | |
321 | ||
322 | static void cgroup_idr_remove(struct idr *idr, int id) | |
323 | { | |
54504e97 | 324 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 325 | idr_remove(idr, id); |
54504e97 | 326 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
327 | } |
328 | ||
d51f39b0 TH |
329 | static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
330 | { | |
331 | struct cgroup_subsys_state *parent_css = cgrp->self.parent; | |
332 | ||
333 | if (parent_css) | |
334 | return container_of(parent_css, struct cgroup, self); | |
335 | return NULL; | |
336 | } | |
337 | ||
95109b62 TH |
338 | /** |
339 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
340 | * @cgrp: the cgroup of interest | |
9d800df1 | 341 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
95109b62 | 342 | * |
ca8bdcaf TH |
343 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
344 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
345 | * the caller is responsible for pinning the returned css if it wants to | |
346 | * keep accessing it outside the said locks. This function may return | |
347 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
348 | */ |
349 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 350 | struct cgroup_subsys *ss) |
95109b62 | 351 | { |
ca8bdcaf | 352 | if (ss) |
aec25020 | 353 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 | 354 | lockdep_is_held(&cgroup_mutex)); |
ca8bdcaf | 355 | else |
9d800df1 | 356 | return &cgrp->self; |
95109b62 | 357 | } |
42809dd4 | 358 | |
aec3dfcb TH |
359 | /** |
360 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem | |
361 | * @cgrp: the cgroup of interest | |
9d800df1 | 362 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
aec3dfcb | 363 | * |
d0f702e6 | 364 | * Similar to cgroup_css() but returns the effective css, which is defined |
aec3dfcb TH |
365 | * as the matching css of the nearest ancestor including self which has @ss |
366 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this | |
367 | * function is guaranteed to return non-NULL css. | |
368 | */ | |
369 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, | |
370 | struct cgroup_subsys *ss) | |
371 | { | |
372 | lockdep_assert_held(&cgroup_mutex); | |
373 | ||
374 | if (!ss) | |
9d800df1 | 375 | return &cgrp->self; |
aec3dfcb TH |
376 | |
377 | if (!(cgrp->root->subsys_mask & (1 << ss->id))) | |
378 | return NULL; | |
379 | ||
eeecbd19 TH |
380 | /* |
381 | * This function is used while updating css associations and thus | |
382 | * can't test the csses directly. Use ->child_subsys_mask. | |
383 | */ | |
d51f39b0 TH |
384 | while (cgroup_parent(cgrp) && |
385 | !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id))) | |
386 | cgrp = cgroup_parent(cgrp); | |
aec3dfcb TH |
387 | |
388 | return cgroup_css(cgrp, ss); | |
95109b62 | 389 | } |
42809dd4 | 390 | |
eeecbd19 TH |
391 | /** |
392 | * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem | |
393 | * @cgrp: the cgroup of interest | |
394 | * @ss: the subsystem of interest | |
395 | * | |
396 | * Find and get the effective css of @cgrp for @ss. The effective css is | |
397 | * defined as the matching css of the nearest ancestor including self which | |
398 | * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, | |
399 | * the root css is returned, so this function always returns a valid css. | |
400 | * The returned css must be put using css_put(). | |
401 | */ | |
402 | struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, | |
403 | struct cgroup_subsys *ss) | |
404 | { | |
405 | struct cgroup_subsys_state *css; | |
406 | ||
407 | rcu_read_lock(); | |
408 | ||
409 | do { | |
410 | css = cgroup_css(cgrp, ss); | |
411 | ||
412 | if (css && css_tryget_online(css)) | |
413 | goto out_unlock; | |
414 | cgrp = cgroup_parent(cgrp); | |
415 | } while (cgrp); | |
416 | ||
417 | css = init_css_set.subsys[ss->id]; | |
418 | css_get(css); | |
419 | out_unlock: | |
420 | rcu_read_unlock(); | |
421 | return css; | |
422 | } | |
423 | ||
ddbcc7e8 | 424 | /* convenient tests for these bits */ |
54766d4a | 425 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 426 | { |
184faf32 | 427 | return !(cgrp->self.flags & CSS_ONLINE); |
ddbcc7e8 PM |
428 | } |
429 | ||
b4168640 | 430 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
59f5296b | 431 | { |
2bd59d48 | 432 | struct cgroup *cgrp = of->kn->parent->priv; |
b4168640 | 433 | struct cftype *cft = of_cft(of); |
2bd59d48 TH |
434 | |
435 | /* | |
436 | * This is open and unprotected implementation of cgroup_css(). | |
437 | * seq_css() is only called from a kernfs file operation which has | |
438 | * an active reference on the file. Because all the subsystem | |
439 | * files are drained before a css is disassociated with a cgroup, | |
440 | * the matching css from the cgroup's subsys table is guaranteed to | |
441 | * be and stay valid until the enclosing operation is complete. | |
442 | */ | |
443 | if (cft->ss) | |
444 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
445 | else | |
9d800df1 | 446 | return &cgrp->self; |
59f5296b | 447 | } |
b4168640 | 448 | EXPORT_SYMBOL_GPL(of_css); |
59f5296b | 449 | |
78574cf9 LZ |
450 | /** |
451 | * cgroup_is_descendant - test ancestry | |
452 | * @cgrp: the cgroup to be tested | |
453 | * @ancestor: possible ancestor of @cgrp | |
454 | * | |
455 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
456 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
457 | * and @ancestor are accessible. | |
458 | */ | |
459 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
460 | { | |
461 | while (cgrp) { | |
462 | if (cgrp == ancestor) | |
463 | return true; | |
d51f39b0 | 464 | cgrp = cgroup_parent(cgrp); |
78574cf9 LZ |
465 | } |
466 | return false; | |
467 | } | |
ddbcc7e8 | 468 | |
e9685a03 | 469 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 470 | { |
bd89aabc | 471 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
472 | } |
473 | ||
1c6727af TH |
474 | /** |
475 | * for_each_css - iterate all css's of a cgroup | |
476 | * @css: the iteration cursor | |
477 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
478 | * @cgrp: the target cgroup to iterate css's of | |
479 | * | |
aec3dfcb | 480 | * Should be called under cgroup_[tree_]mutex. |
1c6727af TH |
481 | */ |
482 | #define for_each_css(css, ssid, cgrp) \ | |
483 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
484 | if (!((css) = rcu_dereference_check( \ | |
485 | (cgrp)->subsys[(ssid)], \ | |
486 | lockdep_is_held(&cgroup_mutex)))) { } \ | |
487 | else | |
488 | ||
aec3dfcb TH |
489 | /** |
490 | * for_each_e_css - iterate all effective css's of a cgroup | |
491 | * @css: the iteration cursor | |
492 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
493 | * @cgrp: the target cgroup to iterate css's of | |
494 | * | |
495 | * Should be called under cgroup_[tree_]mutex. | |
496 | */ | |
497 | #define for_each_e_css(css, ssid, cgrp) \ | |
498 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
499 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ | |
500 | ; \ | |
501 | else | |
502 | ||
30159ec7 | 503 | /** |
3ed80a62 | 504 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 505 | * @ss: the iteration cursor |
780cd8b3 | 506 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 507 | */ |
780cd8b3 | 508 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
509 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
510 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 511 | |
cb4a3167 AS |
512 | /** |
513 | * for_each_subsys_which - filter for_each_subsys with a bitmask | |
514 | * @ss: the iteration cursor | |
515 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end | |
516 | * @ss_maskp: a pointer to the bitmask | |
517 | * | |
518 | * The block will only run for cases where the ssid-th bit (1 << ssid) of | |
519 | * mask is set to 1. | |
520 | */ | |
521 | #define for_each_subsys_which(ss, ssid, ss_maskp) \ | |
522 | if (!CGROUP_SUBSYS_COUNT) /* to avoid spurious gcc warning */ \ | |
4a705c5c | 523 | (ssid) = 0; \ |
cb4a3167 AS |
524 | else \ |
525 | for_each_set_bit(ssid, ss_maskp, CGROUP_SUBSYS_COUNT) \ | |
526 | if (((ss) = cgroup_subsys[ssid]) && false) \ | |
527 | break; \ | |
528 | else | |
529 | ||
985ed670 TH |
530 | /* iterate across the hierarchies */ |
531 | #define for_each_root(root) \ | |
5549c497 | 532 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 533 | |
f8f22e53 TH |
534 | /* iterate over child cgrps, lock should be held throughout iteration */ |
535 | #define cgroup_for_each_live_child(child, cgrp) \ | |
d5c419b6 | 536 | list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
8353da1f | 537 | if (({ lockdep_assert_held(&cgroup_mutex); \ |
f8f22e53 TH |
538 | cgroup_is_dead(child); })) \ |
539 | ; \ | |
540 | else | |
7ae1bad9 | 541 | |
81a6a5cd | 542 | static void cgroup_release_agent(struct work_struct *work); |
bd89aabc | 543 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 544 | |
69d0206c TH |
545 | /* |
546 | * A cgroup can be associated with multiple css_sets as different tasks may | |
547 | * belong to different cgroups on different hierarchies. In the other | |
548 | * direction, a css_set is naturally associated with multiple cgroups. | |
549 | * This M:N relationship is represented by the following link structure | |
550 | * which exists for each association and allows traversing the associations | |
551 | * from both sides. | |
552 | */ | |
553 | struct cgrp_cset_link { | |
554 | /* the cgroup and css_set this link associates */ | |
555 | struct cgroup *cgrp; | |
556 | struct css_set *cset; | |
557 | ||
558 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
559 | struct list_head cset_link; | |
560 | ||
561 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
562 | struct list_head cgrp_link; | |
817929ec PM |
563 | }; |
564 | ||
172a2c06 TH |
565 | /* |
566 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
567 | * hierarchies being mounted. It contains a pointer to the root state |
568 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
569 | * reference-counted, to improve performance when child cgroups | |
570 | * haven't been created. | |
571 | */ | |
5024ae29 | 572 | struct css_set init_css_set = { |
172a2c06 TH |
573 | .refcount = ATOMIC_INIT(1), |
574 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
575 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
576 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
577 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
578 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
579 | }; | |
817929ec | 580 | |
172a2c06 | 581 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 582 | |
842b597e TH |
583 | /** |
584 | * cgroup_update_populated - updated populated count of a cgroup | |
585 | * @cgrp: the target cgroup | |
586 | * @populated: inc or dec populated count | |
587 | * | |
588 | * @cgrp is either getting the first task (css_set) or losing the last. | |
589 | * Update @cgrp->populated_cnt accordingly. The count is propagated | |
590 | * towards root so that a given cgroup's populated_cnt is zero iff the | |
591 | * cgroup and all its descendants are empty. | |
592 | * | |
593 | * @cgrp's interface file "cgroup.populated" is zero if | |
594 | * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt | |
595 | * changes from or to zero, userland is notified that the content of the | |
596 | * interface file has changed. This can be used to detect when @cgrp and | |
597 | * its descendants become populated or empty. | |
598 | */ | |
599 | static void cgroup_update_populated(struct cgroup *cgrp, bool populated) | |
600 | { | |
601 | lockdep_assert_held(&css_set_rwsem); | |
602 | ||
603 | do { | |
604 | bool trigger; | |
605 | ||
606 | if (populated) | |
607 | trigger = !cgrp->populated_cnt++; | |
608 | else | |
609 | trigger = !--cgrp->populated_cnt; | |
610 | ||
611 | if (!trigger) | |
612 | break; | |
613 | ||
4a07c222 TH |
614 | if (cgrp->events_kn) |
615 | kernfs_notify(cgrp->events_kn); | |
d51f39b0 | 616 | cgrp = cgroup_parent(cgrp); |
842b597e TH |
617 | } while (cgrp); |
618 | } | |
619 | ||
7717f7ba PM |
620 | /* |
621 | * hash table for cgroup groups. This improves the performance to find | |
622 | * an existing css_set. This hash doesn't (currently) take into | |
623 | * account cgroups in empty hierarchies. | |
624 | */ | |
472b1053 | 625 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 626 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 627 | |
0ac801fe | 628 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 629 | { |
0ac801fe | 630 | unsigned long key = 0UL; |
30159ec7 TH |
631 | struct cgroup_subsys *ss; |
632 | int i; | |
472b1053 | 633 | |
30159ec7 | 634 | for_each_subsys(ss, i) |
0ac801fe LZ |
635 | key += (unsigned long)css[i]; |
636 | key = (key >> 16) ^ key; | |
472b1053 | 637 | |
0ac801fe | 638 | return key; |
472b1053 LZ |
639 | } |
640 | ||
a25eb52e | 641 | static void put_css_set_locked(struct css_set *cset) |
b4f48b63 | 642 | { |
69d0206c | 643 | struct cgrp_cset_link *link, *tmp_link; |
2d8f243a TH |
644 | struct cgroup_subsys *ss; |
645 | int ssid; | |
5abb8855 | 646 | |
89c5509b TH |
647 | lockdep_assert_held(&css_set_rwsem); |
648 | ||
649 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 650 | return; |
81a6a5cd | 651 | |
2c6ab6d2 | 652 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
2d8f243a TH |
653 | for_each_subsys(ss, ssid) |
654 | list_del(&cset->e_cset_node[ssid]); | |
5abb8855 | 655 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
656 | css_set_count--; |
657 | ||
69d0206c | 658 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 659 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 660 | |
69d0206c TH |
661 | list_del(&link->cset_link); |
662 | list_del(&link->cgrp_link); | |
71b5707e | 663 | |
96d365e0 | 664 | /* @cgrp can't go away while we're holding css_set_rwsem */ |
842b597e TH |
665 | if (list_empty(&cgrp->cset_links)) { |
666 | cgroup_update_populated(cgrp, false); | |
a25eb52e | 667 | check_for_release(cgrp); |
81a6a5cd | 668 | } |
2c6ab6d2 PM |
669 | |
670 | kfree(link); | |
81a6a5cd | 671 | } |
2c6ab6d2 | 672 | |
5abb8855 | 673 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
674 | } |
675 | ||
a25eb52e | 676 | static void put_css_set(struct css_set *cset) |
89c5509b TH |
677 | { |
678 | /* | |
679 | * Ensure that the refcount doesn't hit zero while any readers | |
680 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
681 | * rwlock | |
682 | */ | |
683 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
684 | return; | |
685 | ||
686 | down_write(&css_set_rwsem); | |
a25eb52e | 687 | put_css_set_locked(cset); |
89c5509b TH |
688 | up_write(&css_set_rwsem); |
689 | } | |
690 | ||
817929ec PM |
691 | /* |
692 | * refcounted get/put for css_set objects | |
693 | */ | |
5abb8855 | 694 | static inline void get_css_set(struct css_set *cset) |
817929ec | 695 | { |
5abb8855 | 696 | atomic_inc(&cset->refcount); |
817929ec PM |
697 | } |
698 | ||
b326f9d0 | 699 | /** |
7717f7ba | 700 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
701 | * @cset: candidate css_set being tested |
702 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
703 | * @new_cgrp: cgroup that's being entered by the task |
704 | * @template: desired set of css pointers in css_set (pre-calculated) | |
705 | * | |
6f4b7e63 | 706 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
707 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
708 | */ | |
5abb8855 TH |
709 | static bool compare_css_sets(struct css_set *cset, |
710 | struct css_set *old_cset, | |
7717f7ba PM |
711 | struct cgroup *new_cgrp, |
712 | struct cgroup_subsys_state *template[]) | |
713 | { | |
714 | struct list_head *l1, *l2; | |
715 | ||
aec3dfcb TH |
716 | /* |
717 | * On the default hierarchy, there can be csets which are | |
718 | * associated with the same set of cgroups but different csses. | |
719 | * Let's first ensure that csses match. | |
720 | */ | |
721 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) | |
7717f7ba | 722 | return false; |
7717f7ba PM |
723 | |
724 | /* | |
725 | * Compare cgroup pointers in order to distinguish between | |
aec3dfcb TH |
726 | * different cgroups in hierarchies. As different cgroups may |
727 | * share the same effective css, this comparison is always | |
728 | * necessary. | |
7717f7ba | 729 | */ |
69d0206c TH |
730 | l1 = &cset->cgrp_links; |
731 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 732 | while (1) { |
69d0206c | 733 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 734 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
735 | |
736 | l1 = l1->next; | |
737 | l2 = l2->next; | |
738 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
739 | if (l1 == &cset->cgrp_links) { |
740 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
741 | break; |
742 | } else { | |
69d0206c | 743 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
744 | } |
745 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
746 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
747 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
748 | cgrp1 = link1->cgrp; | |
749 | cgrp2 = link2->cgrp; | |
7717f7ba | 750 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 751 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
752 | |
753 | /* | |
754 | * If this hierarchy is the hierarchy of the cgroup | |
755 | * that's changing, then we need to check that this | |
756 | * css_set points to the new cgroup; if it's any other | |
757 | * hierarchy, then this css_set should point to the | |
758 | * same cgroup as the old css_set. | |
759 | */ | |
5abb8855 TH |
760 | if (cgrp1->root == new_cgrp->root) { |
761 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
762 | return false; |
763 | } else { | |
5abb8855 | 764 | if (cgrp1 != cgrp2) |
7717f7ba PM |
765 | return false; |
766 | } | |
767 | } | |
768 | return true; | |
769 | } | |
770 | ||
b326f9d0 TH |
771 | /** |
772 | * find_existing_css_set - init css array and find the matching css_set | |
773 | * @old_cset: the css_set that we're using before the cgroup transition | |
774 | * @cgrp: the cgroup that we're moving into | |
775 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 776 | */ |
5abb8855 TH |
777 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
778 | struct cgroup *cgrp, | |
779 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 780 | { |
3dd06ffa | 781 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 782 | struct cgroup_subsys *ss; |
5abb8855 | 783 | struct css_set *cset; |
0ac801fe | 784 | unsigned long key; |
b326f9d0 | 785 | int i; |
817929ec | 786 | |
aae8aab4 BB |
787 | /* |
788 | * Build the set of subsystem state objects that we want to see in the | |
789 | * new css_set. while subsystems can change globally, the entries here | |
790 | * won't change, so no need for locking. | |
791 | */ | |
30159ec7 | 792 | for_each_subsys(ss, i) { |
f392e51c | 793 | if (root->subsys_mask & (1UL << i)) { |
aec3dfcb TH |
794 | /* |
795 | * @ss is in this hierarchy, so we want the | |
796 | * effective css from @cgrp. | |
797 | */ | |
798 | template[i] = cgroup_e_css(cgrp, ss); | |
817929ec | 799 | } else { |
aec3dfcb TH |
800 | /* |
801 | * @ss is not in this hierarchy, so we don't want | |
802 | * to change the css. | |
803 | */ | |
5abb8855 | 804 | template[i] = old_cset->subsys[i]; |
817929ec PM |
805 | } |
806 | } | |
807 | ||
0ac801fe | 808 | key = css_set_hash(template); |
5abb8855 TH |
809 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
810 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
811 | continue; |
812 | ||
813 | /* This css_set matches what we need */ | |
5abb8855 | 814 | return cset; |
472b1053 | 815 | } |
817929ec PM |
816 | |
817 | /* No existing cgroup group matched */ | |
818 | return NULL; | |
819 | } | |
820 | ||
69d0206c | 821 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 822 | { |
69d0206c | 823 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 824 | |
69d0206c TH |
825 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
826 | list_del(&link->cset_link); | |
36553434 LZ |
827 | kfree(link); |
828 | } | |
829 | } | |
830 | ||
69d0206c TH |
831 | /** |
832 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
833 | * @count: the number of links to allocate | |
834 | * @tmp_links: list_head the allocated links are put on | |
835 | * | |
836 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
837 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 838 | */ |
69d0206c | 839 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 840 | { |
69d0206c | 841 | struct cgrp_cset_link *link; |
817929ec | 842 | int i; |
69d0206c TH |
843 | |
844 | INIT_LIST_HEAD(tmp_links); | |
845 | ||
817929ec | 846 | for (i = 0; i < count; i++) { |
f4f4be2b | 847 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 848 | if (!link) { |
69d0206c | 849 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
850 | return -ENOMEM; |
851 | } | |
69d0206c | 852 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
853 | } |
854 | return 0; | |
855 | } | |
856 | ||
c12f65d4 LZ |
857 | /** |
858 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 859 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 860 | * @cset: the css_set to be linked |
c12f65d4 LZ |
861 | * @cgrp: the destination cgroup |
862 | */ | |
69d0206c TH |
863 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
864 | struct cgroup *cgrp) | |
c12f65d4 | 865 | { |
69d0206c | 866 | struct cgrp_cset_link *link; |
c12f65d4 | 867 | |
69d0206c | 868 | BUG_ON(list_empty(tmp_links)); |
6803c006 TH |
869 | |
870 | if (cgroup_on_dfl(cgrp)) | |
871 | cset->dfl_cgrp = cgrp; | |
872 | ||
69d0206c TH |
873 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
874 | link->cset = cset; | |
7717f7ba | 875 | link->cgrp = cgrp; |
842b597e TH |
876 | |
877 | if (list_empty(&cgrp->cset_links)) | |
878 | cgroup_update_populated(cgrp, true); | |
69d0206c | 879 | list_move(&link->cset_link, &cgrp->cset_links); |
842b597e | 880 | |
7717f7ba PM |
881 | /* |
882 | * Always add links to the tail of the list so that the list | |
883 | * is sorted by order of hierarchy creation | |
884 | */ | |
69d0206c | 885 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
886 | } |
887 | ||
b326f9d0 TH |
888 | /** |
889 | * find_css_set - return a new css_set with one cgroup updated | |
890 | * @old_cset: the baseline css_set | |
891 | * @cgrp: the cgroup to be updated | |
892 | * | |
893 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
894 | * substituted into the appropriate hierarchy. | |
817929ec | 895 | */ |
5abb8855 TH |
896 | static struct css_set *find_css_set(struct css_set *old_cset, |
897 | struct cgroup *cgrp) | |
817929ec | 898 | { |
b326f9d0 | 899 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 900 | struct css_set *cset; |
69d0206c TH |
901 | struct list_head tmp_links; |
902 | struct cgrp_cset_link *link; | |
2d8f243a | 903 | struct cgroup_subsys *ss; |
0ac801fe | 904 | unsigned long key; |
2d8f243a | 905 | int ssid; |
472b1053 | 906 | |
b326f9d0 TH |
907 | lockdep_assert_held(&cgroup_mutex); |
908 | ||
817929ec PM |
909 | /* First see if we already have a cgroup group that matches |
910 | * the desired set */ | |
96d365e0 | 911 | down_read(&css_set_rwsem); |
5abb8855 TH |
912 | cset = find_existing_css_set(old_cset, cgrp, template); |
913 | if (cset) | |
914 | get_css_set(cset); | |
96d365e0 | 915 | up_read(&css_set_rwsem); |
817929ec | 916 | |
5abb8855 TH |
917 | if (cset) |
918 | return cset; | |
817929ec | 919 | |
f4f4be2b | 920 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 921 | if (!cset) |
817929ec PM |
922 | return NULL; |
923 | ||
69d0206c | 924 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 925 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 926 | kfree(cset); |
817929ec PM |
927 | return NULL; |
928 | } | |
929 | ||
5abb8855 | 930 | atomic_set(&cset->refcount, 1); |
69d0206c | 931 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 932 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 933 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 934 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 935 | INIT_LIST_HEAD(&cset->mg_node); |
5abb8855 | 936 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
937 | |
938 | /* Copy the set of subsystem state objects generated in | |
939 | * find_existing_css_set() */ | |
5abb8855 | 940 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 941 | |
96d365e0 | 942 | down_write(&css_set_rwsem); |
817929ec | 943 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 944 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 945 | struct cgroup *c = link->cgrp; |
69d0206c | 946 | |
7717f7ba PM |
947 | if (c->root == cgrp->root) |
948 | c = cgrp; | |
69d0206c | 949 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 950 | } |
817929ec | 951 | |
69d0206c | 952 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 953 | |
817929ec | 954 | css_set_count++; |
472b1053 | 955 | |
2d8f243a | 956 | /* Add @cset to the hash table */ |
5abb8855 TH |
957 | key = css_set_hash(cset->subsys); |
958 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 959 | |
2d8f243a TH |
960 | for_each_subsys(ss, ssid) |
961 | list_add_tail(&cset->e_cset_node[ssid], | |
962 | &cset->subsys[ssid]->cgroup->e_csets[ssid]); | |
963 | ||
96d365e0 | 964 | up_write(&css_set_rwsem); |
817929ec | 965 | |
5abb8855 | 966 | return cset; |
b4f48b63 PM |
967 | } |
968 | ||
3dd06ffa | 969 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 970 | { |
3dd06ffa | 971 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 972 | |
3dd06ffa | 973 | return root_cgrp->root; |
2bd59d48 TH |
974 | } |
975 | ||
3dd06ffa | 976 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
977 | { |
978 | int id; | |
979 | ||
980 | lockdep_assert_held(&cgroup_mutex); | |
981 | ||
985ed670 | 982 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
983 | if (id < 0) |
984 | return id; | |
985 | ||
986 | root->hierarchy_id = id; | |
987 | return 0; | |
988 | } | |
989 | ||
3dd06ffa | 990 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
991 | { |
992 | lockdep_assert_held(&cgroup_mutex); | |
993 | ||
994 | if (root->hierarchy_id) { | |
995 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
996 | root->hierarchy_id = 0; | |
997 | } | |
998 | } | |
999 | ||
3dd06ffa | 1000 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
1001 | { |
1002 | if (root) { | |
d0f702e6 | 1003 | /* hierarchy ID should already have been released */ |
f2e85d57 TH |
1004 | WARN_ON_ONCE(root->hierarchy_id); |
1005 | ||
1006 | idr_destroy(&root->cgroup_idr); | |
1007 | kfree(root); | |
1008 | } | |
1009 | } | |
1010 | ||
3dd06ffa | 1011 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 1012 | { |
3dd06ffa | 1013 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 1014 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 1015 | |
2bd59d48 | 1016 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 1017 | |
776f02fa | 1018 | BUG_ON(atomic_read(&root->nr_cgrps)); |
d5c419b6 | 1019 | BUG_ON(!list_empty(&cgrp->self.children)); |
f2e85d57 | 1020 | |
f2e85d57 | 1021 | /* Rebind all subsystems back to the default hierarchy */ |
f392e51c | 1022 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); |
7717f7ba | 1023 | |
7717f7ba | 1024 | /* |
f2e85d57 TH |
1025 | * Release all the links from cset_links to this hierarchy's |
1026 | * root cgroup | |
7717f7ba | 1027 | */ |
96d365e0 | 1028 | down_write(&css_set_rwsem); |
f2e85d57 TH |
1029 | |
1030 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
1031 | list_del(&link->cset_link); | |
1032 | list_del(&link->cgrp_link); | |
1033 | kfree(link); | |
1034 | } | |
96d365e0 | 1035 | up_write(&css_set_rwsem); |
f2e85d57 TH |
1036 | |
1037 | if (!list_empty(&root->root_list)) { | |
1038 | list_del(&root->root_list); | |
1039 | cgroup_root_count--; | |
1040 | } | |
1041 | ||
1042 | cgroup_exit_root_id(root); | |
1043 | ||
1044 | mutex_unlock(&cgroup_mutex); | |
f2e85d57 | 1045 | |
2bd59d48 | 1046 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
1047 | cgroup_free_root(root); |
1048 | } | |
1049 | ||
ceb6a081 TH |
1050 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
1051 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 1052 | struct cgroup_root *root) |
7717f7ba | 1053 | { |
7717f7ba PM |
1054 | struct cgroup *res = NULL; |
1055 | ||
96d365e0 TH |
1056 | lockdep_assert_held(&cgroup_mutex); |
1057 | lockdep_assert_held(&css_set_rwsem); | |
1058 | ||
5abb8855 | 1059 | if (cset == &init_css_set) { |
3dd06ffa | 1060 | res = &root->cgrp; |
7717f7ba | 1061 | } else { |
69d0206c TH |
1062 | struct cgrp_cset_link *link; |
1063 | ||
1064 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 1065 | struct cgroup *c = link->cgrp; |
69d0206c | 1066 | |
7717f7ba PM |
1067 | if (c->root == root) { |
1068 | res = c; | |
1069 | break; | |
1070 | } | |
1071 | } | |
1072 | } | |
96d365e0 | 1073 | |
7717f7ba PM |
1074 | BUG_ON(!res); |
1075 | return res; | |
1076 | } | |
1077 | ||
ddbcc7e8 | 1078 | /* |
ceb6a081 TH |
1079 | * Return the cgroup for "task" from the given hierarchy. Must be |
1080 | * called with cgroup_mutex and css_set_rwsem held. | |
1081 | */ | |
1082 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 1083 | struct cgroup_root *root) |
ceb6a081 TH |
1084 | { |
1085 | /* | |
1086 | * No need to lock the task - since we hold cgroup_mutex the | |
1087 | * task can't change groups, so the only thing that can happen | |
1088 | * is that it exits and its css is set back to init_css_set. | |
1089 | */ | |
1090 | return cset_cgroup_from_root(task_css_set(task), root); | |
1091 | } | |
1092 | ||
ddbcc7e8 | 1093 | /* |
ddbcc7e8 PM |
1094 | * A task must hold cgroup_mutex to modify cgroups. |
1095 | * | |
1096 | * Any task can increment and decrement the count field without lock. | |
1097 | * So in general, code holding cgroup_mutex can't rely on the count | |
1098 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 1099 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
1100 | * means that no tasks are currently attached, therefore there is no |
1101 | * way a task attached to that cgroup can fork (the other way to | |
1102 | * increment the count). So code holding cgroup_mutex can safely | |
1103 | * assume that if the count is zero, it will stay zero. Similarly, if | |
1104 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
1105 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
1106 | * needs that mutex. | |
1107 | * | |
ddbcc7e8 PM |
1108 | * A cgroup can only be deleted if both its 'count' of using tasks |
1109 | * is zero, and its list of 'children' cgroups is empty. Since all | |
1110 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 1111 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 1112 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 1113 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
1114 | * |
1115 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 1116 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
1117 | */ |
1118 | ||
8ab456ac | 1119 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); |
2bd59d48 | 1120 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 1121 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 1122 | |
8d7e6fb0 TH |
1123 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
1124 | char *buf) | |
ddbcc7e8 | 1125 | { |
3e1d2eed TH |
1126 | struct cgroup_subsys *ss = cft->ss; |
1127 | ||
8d7e6fb0 TH |
1128 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
1129 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
1130 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
3e1d2eed TH |
1131 | cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
1132 | cft->name); | |
8d7e6fb0 TH |
1133 | else |
1134 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
1135 | return buf; | |
ddbcc7e8 PM |
1136 | } |
1137 | ||
f2e85d57 TH |
1138 | /** |
1139 | * cgroup_file_mode - deduce file mode of a control file | |
1140 | * @cft: the control file in question | |
1141 | * | |
1142 | * returns cft->mode if ->mode is not 0 | |
1143 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
1144 | * returns S_IRUGO if it has only a read handler | |
1145 | * returns S_IWUSR if it has only a write hander | |
1146 | */ | |
1147 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 1148 | { |
f2e85d57 | 1149 | umode_t mode = 0; |
65dff759 | 1150 | |
f2e85d57 TH |
1151 | if (cft->mode) |
1152 | return cft->mode; | |
1153 | ||
1154 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) | |
1155 | mode |= S_IRUGO; | |
1156 | ||
6770c64e | 1157 | if (cft->write_u64 || cft->write_s64 || cft->write) |
f2e85d57 TH |
1158 | mode |= S_IWUSR; |
1159 | ||
1160 | return mode; | |
65dff759 LZ |
1161 | } |
1162 | ||
59f5296b | 1163 | static void cgroup_get(struct cgroup *cgrp) |
be445626 | 1164 | { |
2bd59d48 | 1165 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
9d755d33 | 1166 | css_get(&cgrp->self); |
be445626 LZ |
1167 | } |
1168 | ||
aa32362f LZ |
1169 | static bool cgroup_tryget(struct cgroup *cgrp) |
1170 | { | |
1171 | return css_tryget(&cgrp->self); | |
1172 | } | |
1173 | ||
59f5296b | 1174 | static void cgroup_put(struct cgroup *cgrp) |
be445626 | 1175 | { |
9d755d33 | 1176 | css_put(&cgrp->self); |
be445626 LZ |
1177 | } |
1178 | ||
af0ba678 | 1179 | /** |
0f060deb | 1180 | * cgroup_calc_child_subsys_mask - calculate child_subsys_mask |
af0ba678 | 1181 | * @cgrp: the target cgroup |
0f060deb | 1182 | * @subtree_control: the new subtree_control mask to consider |
af0ba678 TH |
1183 | * |
1184 | * On the default hierarchy, a subsystem may request other subsystems to be | |
1185 | * enabled together through its ->depends_on mask. In such cases, more | |
1186 | * subsystems than specified in "cgroup.subtree_control" may be enabled. | |
1187 | * | |
0f060deb TH |
1188 | * This function calculates which subsystems need to be enabled if |
1189 | * @subtree_control is to be applied to @cgrp. The returned mask is always | |
1190 | * a superset of @subtree_control and follows the usual hierarchy rules. | |
af0ba678 | 1191 | */ |
8ab456ac AS |
1192 | static unsigned long cgroup_calc_child_subsys_mask(struct cgroup *cgrp, |
1193 | unsigned long subtree_control) | |
667c2491 | 1194 | { |
af0ba678 | 1195 | struct cgroup *parent = cgroup_parent(cgrp); |
8ab456ac | 1196 | unsigned long cur_ss_mask = subtree_control; |
af0ba678 TH |
1197 | struct cgroup_subsys *ss; |
1198 | int ssid; | |
1199 | ||
1200 | lockdep_assert_held(&cgroup_mutex); | |
1201 | ||
0f060deb TH |
1202 | if (!cgroup_on_dfl(cgrp)) |
1203 | return cur_ss_mask; | |
af0ba678 TH |
1204 | |
1205 | while (true) { | |
8ab456ac | 1206 | unsigned long new_ss_mask = cur_ss_mask; |
af0ba678 | 1207 | |
a966a4ed AS |
1208 | for_each_subsys_which(ss, ssid, &cur_ss_mask) |
1209 | new_ss_mask |= ss->depends_on; | |
af0ba678 TH |
1210 | |
1211 | /* | |
1212 | * Mask out subsystems which aren't available. This can | |
1213 | * happen only if some depended-upon subsystems were bound | |
1214 | * to non-default hierarchies. | |
1215 | */ | |
1216 | if (parent) | |
1217 | new_ss_mask &= parent->child_subsys_mask; | |
1218 | else | |
1219 | new_ss_mask &= cgrp->root->subsys_mask; | |
1220 | ||
1221 | if (new_ss_mask == cur_ss_mask) | |
1222 | break; | |
1223 | cur_ss_mask = new_ss_mask; | |
1224 | } | |
1225 | ||
0f060deb TH |
1226 | return cur_ss_mask; |
1227 | } | |
1228 | ||
1229 | /** | |
1230 | * cgroup_refresh_child_subsys_mask - update child_subsys_mask | |
1231 | * @cgrp: the target cgroup | |
1232 | * | |
1233 | * Update @cgrp->child_subsys_mask according to the current | |
1234 | * @cgrp->subtree_control using cgroup_calc_child_subsys_mask(). | |
1235 | */ | |
1236 | static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp) | |
1237 | { | |
1238 | cgrp->child_subsys_mask = | |
1239 | cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control); | |
667c2491 TH |
1240 | } |
1241 | ||
a9746d8d TH |
1242 | /** |
1243 | * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods | |
1244 | * @kn: the kernfs_node being serviced | |
1245 | * | |
1246 | * This helper undoes cgroup_kn_lock_live() and should be invoked before | |
1247 | * the method finishes if locking succeeded. Note that once this function | |
1248 | * returns the cgroup returned by cgroup_kn_lock_live() may become | |
1249 | * inaccessible any time. If the caller intends to continue to access the | |
1250 | * cgroup, it should pin it before invoking this function. | |
1251 | */ | |
1252 | static void cgroup_kn_unlock(struct kernfs_node *kn) | |
ddbcc7e8 | 1253 | { |
a9746d8d TH |
1254 | struct cgroup *cgrp; |
1255 | ||
1256 | if (kernfs_type(kn) == KERNFS_DIR) | |
1257 | cgrp = kn->priv; | |
1258 | else | |
1259 | cgrp = kn->parent->priv; | |
1260 | ||
1261 | mutex_unlock(&cgroup_mutex); | |
a9746d8d TH |
1262 | |
1263 | kernfs_unbreak_active_protection(kn); | |
1264 | cgroup_put(cgrp); | |
ddbcc7e8 PM |
1265 | } |
1266 | ||
a9746d8d TH |
1267 | /** |
1268 | * cgroup_kn_lock_live - locking helper for cgroup kernfs methods | |
1269 | * @kn: the kernfs_node being serviced | |
1270 | * | |
1271 | * This helper is to be used by a cgroup kernfs method currently servicing | |
1272 | * @kn. It breaks the active protection, performs cgroup locking and | |
1273 | * verifies that the associated cgroup is alive. Returns the cgroup if | |
1274 | * alive; otherwise, %NULL. A successful return should be undone by a | |
1275 | * matching cgroup_kn_unlock() invocation. | |
1276 | * | |
1277 | * Any cgroup kernfs method implementation which requires locking the | |
1278 | * associated cgroup should use this helper. It avoids nesting cgroup | |
1279 | * locking under kernfs active protection and allows all kernfs operations | |
1280 | * including self-removal. | |
1281 | */ | |
1282 | static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn) | |
05ef1d7c | 1283 | { |
a9746d8d TH |
1284 | struct cgroup *cgrp; |
1285 | ||
1286 | if (kernfs_type(kn) == KERNFS_DIR) | |
1287 | cgrp = kn->priv; | |
1288 | else | |
1289 | cgrp = kn->parent->priv; | |
05ef1d7c | 1290 | |
2739d3cc | 1291 | /* |
01f6474c | 1292 | * We're gonna grab cgroup_mutex which nests outside kernfs |
a9746d8d TH |
1293 | * active_ref. cgroup liveliness check alone provides enough |
1294 | * protection against removal. Ensure @cgrp stays accessible and | |
1295 | * break the active_ref protection. | |
2739d3cc | 1296 | */ |
aa32362f LZ |
1297 | if (!cgroup_tryget(cgrp)) |
1298 | return NULL; | |
a9746d8d TH |
1299 | kernfs_break_active_protection(kn); |
1300 | ||
2bd59d48 | 1301 | mutex_lock(&cgroup_mutex); |
05ef1d7c | 1302 | |
a9746d8d TH |
1303 | if (!cgroup_is_dead(cgrp)) |
1304 | return cgrp; | |
1305 | ||
1306 | cgroup_kn_unlock(kn); | |
1307 | return NULL; | |
ddbcc7e8 | 1308 | } |
05ef1d7c | 1309 | |
2739d3cc | 1310 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 1311 | { |
2bd59d48 | 1312 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 1313 | |
01f6474c | 1314 | lockdep_assert_held(&cgroup_mutex); |
2bd59d48 | 1315 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
1316 | } |
1317 | ||
13af07df | 1318 | /** |
628f7cd4 | 1319 | * cgroup_clear_dir - remove subsys files in a cgroup directory |
8f89140a | 1320 | * @cgrp: target cgroup |
13af07df AR |
1321 | * @subsys_mask: mask of the subsystem ids whose files should be removed |
1322 | */ | |
8ab456ac | 1323 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
05ef1d7c | 1324 | { |
13af07df | 1325 | struct cgroup_subsys *ss; |
b420ba7d | 1326 | int i; |
05ef1d7c | 1327 | |
b420ba7d | 1328 | for_each_subsys(ss, i) { |
0adb0704 | 1329 | struct cftype *cfts; |
b420ba7d | 1330 | |
69dfa00c | 1331 | if (!(subsys_mask & (1 << i))) |
13af07df | 1332 | continue; |
0adb0704 TH |
1333 | list_for_each_entry(cfts, &ss->cfts, node) |
1334 | cgroup_addrm_files(cgrp, cfts, false); | |
13af07df | 1335 | } |
ddbcc7e8 PM |
1336 | } |
1337 | ||
8ab456ac AS |
1338 | static int rebind_subsystems(struct cgroup_root *dst_root, |
1339 | unsigned long ss_mask) | |
ddbcc7e8 | 1340 | { |
30159ec7 | 1341 | struct cgroup_subsys *ss; |
8ab456ac | 1342 | unsigned long tmp_ss_mask; |
2d8f243a | 1343 | int ssid, i, ret; |
ddbcc7e8 | 1344 | |
ace2bee8 | 1345 | lockdep_assert_held(&cgroup_mutex); |
ddbcc7e8 | 1346 | |
a966a4ed | 1347 | for_each_subsys_which(ss, ssid, &ss_mask) { |
7fd8c565 TH |
1348 | /* if @ss has non-root csses attached to it, can't move */ |
1349 | if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) | |
3ed80a62 | 1350 | return -EBUSY; |
1d5be6b2 | 1351 | |
5df36032 | 1352 | /* can't move between two non-dummy roots either */ |
7fd8c565 | 1353 | if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
5df36032 | 1354 | return -EBUSY; |
ddbcc7e8 PM |
1355 | } |
1356 | ||
5533e011 TH |
1357 | /* skip creating root files on dfl_root for inhibited subsystems */ |
1358 | tmp_ss_mask = ss_mask; | |
1359 | if (dst_root == &cgrp_dfl_root) | |
1360 | tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask; | |
1361 | ||
1362 | ret = cgroup_populate_dir(&dst_root->cgrp, tmp_ss_mask); | |
a2dd4247 TH |
1363 | if (ret) { |
1364 | if (dst_root != &cgrp_dfl_root) | |
5df36032 | 1365 | return ret; |
ddbcc7e8 | 1366 | |
a2dd4247 TH |
1367 | /* |
1368 | * Rebinding back to the default root is not allowed to | |
1369 | * fail. Using both default and non-default roots should | |
1370 | * be rare. Moving subsystems back and forth even more so. | |
1371 | * Just warn about it and continue. | |
1372 | */ | |
1373 | if (cgrp_dfl_root_visible) { | |
8ab456ac | 1374 | pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n", |
a2a1f9ea | 1375 | ret, ss_mask); |
ed3d261b | 1376 | pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); |
a2dd4247 | 1377 | } |
5df36032 | 1378 | } |
3126121f TH |
1379 | |
1380 | /* | |
1381 | * Nothing can fail from this point on. Remove files for the | |
1382 | * removed subsystems and rebind each subsystem. | |
1383 | */ | |
a966a4ed AS |
1384 | for_each_subsys_which(ss, ssid, &ss_mask) |
1385 | cgroup_clear_dir(&ss->root->cgrp, 1 << ssid); | |
a8a648c4 | 1386 | |
a966a4ed | 1387 | for_each_subsys_which(ss, ssid, &ss_mask) { |
3dd06ffa | 1388 | struct cgroup_root *src_root; |
5df36032 | 1389 | struct cgroup_subsys_state *css; |
2d8f243a | 1390 | struct css_set *cset; |
a8a648c4 | 1391 | |
5df36032 | 1392 | src_root = ss->root; |
3dd06ffa | 1393 | css = cgroup_css(&src_root->cgrp, ss); |
a8a648c4 | 1394 | |
3dd06ffa | 1395 | WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss)); |
73e80ed8 | 1396 | |
3dd06ffa TH |
1397 | RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL); |
1398 | rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css); | |
5df36032 | 1399 | ss->root = dst_root; |
3dd06ffa | 1400 | css->cgroup = &dst_root->cgrp; |
73e80ed8 | 1401 | |
2d8f243a TH |
1402 | down_write(&css_set_rwsem); |
1403 | hash_for_each(css_set_table, i, cset, hlist) | |
1404 | list_move_tail(&cset->e_cset_node[ss->id], | |
1405 | &dst_root->cgrp.e_csets[ss->id]); | |
1406 | up_write(&css_set_rwsem); | |
1407 | ||
f392e51c | 1408 | src_root->subsys_mask &= ~(1 << ssid); |
667c2491 TH |
1409 | src_root->cgrp.subtree_control &= ~(1 << ssid); |
1410 | cgroup_refresh_child_subsys_mask(&src_root->cgrp); | |
f392e51c | 1411 | |
bd53d617 | 1412 | /* default hierarchy doesn't enable controllers by default */ |
f392e51c | 1413 | dst_root->subsys_mask |= 1 << ssid; |
49d1dc4b TH |
1414 | if (dst_root == &cgrp_dfl_root) { |
1415 | static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); | |
1416 | } else { | |
667c2491 TH |
1417 | dst_root->cgrp.subtree_control |= 1 << ssid; |
1418 | cgroup_refresh_child_subsys_mask(&dst_root->cgrp); | |
49d1dc4b | 1419 | static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
667c2491 | 1420 | } |
a8a648c4 | 1421 | |
5df36032 TH |
1422 | if (ss->bind) |
1423 | ss->bind(css); | |
ddbcc7e8 | 1424 | } |
ddbcc7e8 | 1425 | |
a2dd4247 | 1426 | kernfs_activate(dst_root->cgrp.kn); |
ddbcc7e8 PM |
1427 | return 0; |
1428 | } | |
1429 | ||
2bd59d48 TH |
1430 | static int cgroup_show_options(struct seq_file *seq, |
1431 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1432 | { |
3dd06ffa | 1433 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1434 | struct cgroup_subsys *ss; |
b85d2040 | 1435 | int ssid; |
ddbcc7e8 | 1436 | |
d98817d4 TH |
1437 | if (root != &cgrp_dfl_root) |
1438 | for_each_subsys(ss, ssid) | |
1439 | if (root->subsys_mask & (1 << ssid)) | |
61e57c0c | 1440 | seq_show_option(seq, ss->legacy_name, NULL); |
93438629 | 1441 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1442 | seq_puts(seq, ",noprefix"); |
93438629 | 1443 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1444 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1445 | |
1446 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1447 | if (strlen(root->release_agent_path)) |
a068acf2 KC |
1448 | seq_show_option(seq, "release_agent", |
1449 | root->release_agent_path); | |
69e943b7 TH |
1450 | spin_unlock(&release_agent_path_lock); |
1451 | ||
3dd06ffa | 1452 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1453 | seq_puts(seq, ",clone_children"); |
c6d57f33 | 1454 | if (strlen(root->name)) |
a068acf2 | 1455 | seq_show_option(seq, "name", root->name); |
ddbcc7e8 PM |
1456 | return 0; |
1457 | } | |
1458 | ||
1459 | struct cgroup_sb_opts { | |
8ab456ac | 1460 | unsigned long subsys_mask; |
69dfa00c | 1461 | unsigned int flags; |
81a6a5cd | 1462 | char *release_agent; |
2260e7fc | 1463 | bool cpuset_clone_children; |
c6d57f33 | 1464 | char *name; |
2c6ab6d2 PM |
1465 | /* User explicitly requested empty subsystem */ |
1466 | bool none; | |
ddbcc7e8 PM |
1467 | }; |
1468 | ||
cf5d5941 | 1469 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1470 | { |
32a8cf23 DL |
1471 | char *token, *o = data; |
1472 | bool all_ss = false, one_ss = false; | |
8ab456ac | 1473 | unsigned long mask = -1UL; |
30159ec7 | 1474 | struct cgroup_subsys *ss; |
7b9a6ba5 | 1475 | int nr_opts = 0; |
30159ec7 | 1476 | int i; |
f9ab5b5b LZ |
1477 | |
1478 | #ifdef CONFIG_CPUSETS | |
69dfa00c | 1479 | mask = ~(1U << cpuset_cgrp_id); |
f9ab5b5b | 1480 | #endif |
ddbcc7e8 | 1481 | |
c6d57f33 | 1482 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1483 | |
1484 | while ((token = strsep(&o, ",")) != NULL) { | |
7b9a6ba5 TH |
1485 | nr_opts++; |
1486 | ||
ddbcc7e8 PM |
1487 | if (!*token) |
1488 | return -EINVAL; | |
32a8cf23 | 1489 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1490 | /* Explicitly have no subsystems */ |
1491 | opts->none = true; | |
32a8cf23 DL |
1492 | continue; |
1493 | } | |
1494 | if (!strcmp(token, "all")) { | |
1495 | /* Mutually exclusive option 'all' + subsystem name */ | |
1496 | if (one_ss) | |
1497 | return -EINVAL; | |
1498 | all_ss = true; | |
1499 | continue; | |
1500 | } | |
873fe09e TH |
1501 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1502 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1503 | continue; | |
1504 | } | |
32a8cf23 | 1505 | if (!strcmp(token, "noprefix")) { |
93438629 | 1506 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1507 | continue; |
1508 | } | |
1509 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1510 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1511 | continue; |
1512 | } | |
03b1cde6 | 1513 | if (!strcmp(token, "xattr")) { |
93438629 | 1514 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1515 | continue; |
1516 | } | |
32a8cf23 | 1517 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1518 | /* Specifying two release agents is forbidden */ |
1519 | if (opts->release_agent) | |
1520 | return -EINVAL; | |
c6d57f33 | 1521 | opts->release_agent = |
e400c285 | 1522 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1523 | if (!opts->release_agent) |
1524 | return -ENOMEM; | |
32a8cf23 DL |
1525 | continue; |
1526 | } | |
1527 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1528 | const char *name = token + 5; |
1529 | /* Can't specify an empty name */ | |
1530 | if (!strlen(name)) | |
1531 | return -EINVAL; | |
1532 | /* Must match [\w.-]+ */ | |
1533 | for (i = 0; i < strlen(name); i++) { | |
1534 | char c = name[i]; | |
1535 | if (isalnum(c)) | |
1536 | continue; | |
1537 | if ((c == '.') || (c == '-') || (c == '_')) | |
1538 | continue; | |
1539 | return -EINVAL; | |
1540 | } | |
1541 | /* Specifying two names is forbidden */ | |
1542 | if (opts->name) | |
1543 | return -EINVAL; | |
1544 | opts->name = kstrndup(name, | |
e400c285 | 1545 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1546 | GFP_KERNEL); |
1547 | if (!opts->name) | |
1548 | return -ENOMEM; | |
32a8cf23 DL |
1549 | |
1550 | continue; | |
1551 | } | |
1552 | ||
30159ec7 | 1553 | for_each_subsys(ss, i) { |
3e1d2eed | 1554 | if (strcmp(token, ss->legacy_name)) |
32a8cf23 | 1555 | continue; |
fc5ed1e9 | 1556 | if (!cgroup_ssid_enabled(i)) |
32a8cf23 DL |
1557 | continue; |
1558 | ||
1559 | /* Mutually exclusive option 'all' + subsystem name */ | |
1560 | if (all_ss) | |
1561 | return -EINVAL; | |
69dfa00c | 1562 | opts->subsys_mask |= (1 << i); |
32a8cf23 DL |
1563 | one_ss = true; |
1564 | ||
1565 | break; | |
1566 | } | |
1567 | if (i == CGROUP_SUBSYS_COUNT) | |
1568 | return -ENOENT; | |
1569 | } | |
1570 | ||
873fe09e | 1571 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
ed3d261b | 1572 | pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); |
7b9a6ba5 TH |
1573 | if (nr_opts != 1) { |
1574 | pr_err("sane_behavior: no other mount options allowed\n"); | |
873fe09e TH |
1575 | return -EINVAL; |
1576 | } | |
7b9a6ba5 | 1577 | return 0; |
873fe09e TH |
1578 | } |
1579 | ||
7b9a6ba5 TH |
1580 | /* |
1581 | * If the 'all' option was specified select all the subsystems, | |
1582 | * otherwise if 'none', 'name=' and a subsystem name options were | |
1583 | * not specified, let's default to 'all' | |
1584 | */ | |
1585 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1586 | for_each_subsys(ss, i) | |
fc5ed1e9 | 1587 | if (cgroup_ssid_enabled(i)) |
7b9a6ba5 TH |
1588 | opts->subsys_mask |= (1 << i); |
1589 | ||
1590 | /* | |
1591 | * We either have to specify by name or by subsystems. (So all | |
1592 | * empty hierarchies must have a name). | |
1593 | */ | |
1594 | if (!opts->subsys_mask && !opts->name) | |
1595 | return -EINVAL; | |
1596 | ||
f9ab5b5b LZ |
1597 | /* |
1598 | * Option noprefix was introduced just for backward compatibility | |
1599 | * with the old cpuset, so we allow noprefix only if mounting just | |
1600 | * the cpuset subsystem. | |
1601 | */ | |
93438629 | 1602 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1603 | return -EINVAL; |
1604 | ||
2c6ab6d2 | 1605 | /* Can't specify "none" and some subsystems */ |
a1a71b45 | 1606 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1607 | return -EINVAL; |
1608 | ||
ddbcc7e8 PM |
1609 | return 0; |
1610 | } | |
1611 | ||
2bd59d48 | 1612 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1613 | { |
1614 | int ret = 0; | |
3dd06ffa | 1615 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1616 | struct cgroup_sb_opts opts; |
8ab456ac | 1617 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1618 | |
aa6ec29b TH |
1619 | if (root == &cgrp_dfl_root) { |
1620 | pr_err("remount is not allowed\n"); | |
873fe09e TH |
1621 | return -EINVAL; |
1622 | } | |
1623 | ||
ddbcc7e8 PM |
1624 | mutex_lock(&cgroup_mutex); |
1625 | ||
1626 | /* See what subsystems are wanted */ | |
1627 | ret = parse_cgroupfs_options(data, &opts); | |
1628 | if (ret) | |
1629 | goto out_unlock; | |
1630 | ||
f392e51c | 1631 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
ed3d261b | 1632 | pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
a2a1f9ea | 1633 | task_tgid_nr(current), current->comm); |
8b5a5a9d | 1634 | |
f392e51c TH |
1635 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1636 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1637 | |
cf5d5941 | 1638 | /* Don't allow flags or name to change at remount */ |
7450e90b | 1639 | if ((opts.flags ^ root->flags) || |
cf5d5941 | 1640 | (opts.name && strcmp(opts.name, root->name))) { |
69dfa00c | 1641 | pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
7450e90b | 1642 | opts.flags, opts.name ?: "", root->flags, root->name); |
c6d57f33 PM |
1643 | ret = -EINVAL; |
1644 | goto out_unlock; | |
1645 | } | |
1646 | ||
f172e67c | 1647 | /* remounting is not allowed for populated hierarchies */ |
d5c419b6 | 1648 | if (!list_empty(&root->cgrp.self.children)) { |
f172e67c | 1649 | ret = -EBUSY; |
0670e08b | 1650 | goto out_unlock; |
cf5d5941 | 1651 | } |
ddbcc7e8 | 1652 | |
5df36032 | 1653 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1654 | if (ret) |
0670e08b | 1655 | goto out_unlock; |
ddbcc7e8 | 1656 | |
3dd06ffa | 1657 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1658 | |
69e943b7 TH |
1659 | if (opts.release_agent) { |
1660 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1661 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1662 | spin_unlock(&release_agent_path_lock); |
1663 | } | |
ddbcc7e8 | 1664 | out_unlock: |
66bdc9cf | 1665 | kfree(opts.release_agent); |
c6d57f33 | 1666 | kfree(opts.name); |
ddbcc7e8 | 1667 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
1668 | return ret; |
1669 | } | |
1670 | ||
afeb0f9f TH |
1671 | /* |
1672 | * To reduce the fork() overhead for systems that are not actually using | |
1673 | * their cgroups capability, we don't maintain the lists running through | |
1674 | * each css_set to its tasks until we see the list actually used - in other | |
1675 | * words after the first mount. | |
1676 | */ | |
1677 | static bool use_task_css_set_links __read_mostly; | |
1678 | ||
1679 | static void cgroup_enable_task_cg_lists(void) | |
1680 | { | |
1681 | struct task_struct *p, *g; | |
1682 | ||
96d365e0 | 1683 | down_write(&css_set_rwsem); |
afeb0f9f TH |
1684 | |
1685 | if (use_task_css_set_links) | |
1686 | goto out_unlock; | |
1687 | ||
1688 | use_task_css_set_links = true; | |
1689 | ||
1690 | /* | |
1691 | * We need tasklist_lock because RCU is not safe against | |
1692 | * while_each_thread(). Besides, a forking task that has passed | |
1693 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1694 | * is not guaranteed to have its child immediately visible in the | |
1695 | * tasklist if we walk through it with RCU. | |
1696 | */ | |
1697 | read_lock(&tasklist_lock); | |
1698 | do_each_thread(g, p) { | |
afeb0f9f TH |
1699 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1700 | task_css_set(p) != &init_css_set); | |
1701 | ||
1702 | /* | |
1703 | * We should check if the process is exiting, otherwise | |
1704 | * it will race with cgroup_exit() in that the list | |
1705 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1706 | * Do it while holding siglock so that we don't end up |
1707 | * racing against cgroup_exit(). | |
afeb0f9f | 1708 | */ |
f153ad11 | 1709 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1710 | if (!(p->flags & PF_EXITING)) { |
1711 | struct css_set *cset = task_css_set(p); | |
1712 | ||
1713 | list_add(&p->cg_list, &cset->tasks); | |
1714 | get_css_set(cset); | |
1715 | } | |
f153ad11 | 1716 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1717 | } while_each_thread(g, p); |
1718 | read_unlock(&tasklist_lock); | |
1719 | out_unlock: | |
96d365e0 | 1720 | up_write(&css_set_rwsem); |
afeb0f9f | 1721 | } |
ddbcc7e8 | 1722 | |
cc31edce PM |
1723 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1724 | { | |
2d8f243a TH |
1725 | struct cgroup_subsys *ss; |
1726 | int ssid; | |
1727 | ||
d5c419b6 TH |
1728 | INIT_LIST_HEAD(&cgrp->self.sibling); |
1729 | INIT_LIST_HEAD(&cgrp->self.children); | |
69d0206c | 1730 | INIT_LIST_HEAD(&cgrp->cset_links); |
72a8cb30 BB |
1731 | INIT_LIST_HEAD(&cgrp->pidlists); |
1732 | mutex_init(&cgrp->pidlist_mutex); | |
9d800df1 | 1733 | cgrp->self.cgroup = cgrp; |
184faf32 | 1734 | cgrp->self.flags |= CSS_ONLINE; |
2d8f243a TH |
1735 | |
1736 | for_each_subsys(ss, ssid) | |
1737 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]); | |
f8f22e53 TH |
1738 | |
1739 | init_waitqueue_head(&cgrp->offline_waitq); | |
971ff493 | 1740 | INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
cc31edce | 1741 | } |
c6d57f33 | 1742 | |
3dd06ffa | 1743 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1744 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1745 | { |
3dd06ffa | 1746 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1747 | |
ddbcc7e8 | 1748 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1749 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1750 | cgrp->root = root; |
cc31edce | 1751 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1752 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1753 | |
c6d57f33 PM |
1754 | root->flags = opts->flags; |
1755 | if (opts->release_agent) | |
1756 | strcpy(root->release_agent_path, opts->release_agent); | |
1757 | if (opts->name) | |
1758 | strcpy(root->name, opts->name); | |
2260e7fc | 1759 | if (opts->cpuset_clone_children) |
3dd06ffa | 1760 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1761 | } |
1762 | ||
8ab456ac | 1763 | static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) |
2c6ab6d2 | 1764 | { |
d427dfeb | 1765 | LIST_HEAD(tmp_links); |
3dd06ffa | 1766 | struct cgroup *root_cgrp = &root->cgrp; |
a14c6874 | 1767 | struct cftype *base_files; |
d427dfeb | 1768 | struct css_set *cset; |
d427dfeb | 1769 | int i, ret; |
2c6ab6d2 | 1770 | |
d427dfeb | 1771 | lockdep_assert_held(&cgroup_mutex); |
c6d57f33 | 1772 | |
cf780b7d | 1773 | ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
d427dfeb | 1774 | if (ret < 0) |
2bd59d48 | 1775 | goto out; |
d427dfeb | 1776 | root_cgrp->id = ret; |
c6d57f33 | 1777 | |
2aad2a86 TH |
1778 | ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, |
1779 | GFP_KERNEL); | |
9d755d33 TH |
1780 | if (ret) |
1781 | goto out; | |
1782 | ||
d427dfeb | 1783 | /* |
96d365e0 | 1784 | * We're accessing css_set_count without locking css_set_rwsem here, |
d427dfeb TH |
1785 | * but that's OK - it can only be increased by someone holding |
1786 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1787 | * have some link structures left over | |
1788 | */ | |
1789 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1790 | if (ret) | |
9d755d33 | 1791 | goto cancel_ref; |
ddbcc7e8 | 1792 | |
985ed670 | 1793 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1794 | if (ret) |
9d755d33 | 1795 | goto cancel_ref; |
ddbcc7e8 | 1796 | |
2bd59d48 TH |
1797 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1798 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1799 | root_cgrp); | |
1800 | if (IS_ERR(root->kf_root)) { | |
1801 | ret = PTR_ERR(root->kf_root); | |
1802 | goto exit_root_id; | |
1803 | } | |
1804 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1805 | |
a14c6874 TH |
1806 | if (root == &cgrp_dfl_root) |
1807 | base_files = cgroup_dfl_base_files; | |
1808 | else | |
1809 | base_files = cgroup_legacy_base_files; | |
1810 | ||
1811 | ret = cgroup_addrm_files(root_cgrp, base_files, true); | |
d427dfeb | 1812 | if (ret) |
2bd59d48 | 1813 | goto destroy_root; |
ddbcc7e8 | 1814 | |
5df36032 | 1815 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1816 | if (ret) |
2bd59d48 | 1817 | goto destroy_root; |
ddbcc7e8 | 1818 | |
d427dfeb TH |
1819 | /* |
1820 | * There must be no failure case after here, since rebinding takes | |
1821 | * care of subsystems' refcounts, which are explicitly dropped in | |
1822 | * the failure exit path. | |
1823 | */ | |
1824 | list_add(&root->root_list, &cgroup_roots); | |
1825 | cgroup_root_count++; | |
0df6a63f | 1826 | |
d427dfeb | 1827 | /* |
3dd06ffa | 1828 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1829 | * objects. |
1830 | */ | |
96d365e0 | 1831 | down_write(&css_set_rwsem); |
d427dfeb TH |
1832 | hash_for_each(css_set_table, i, cset, hlist) |
1833 | link_css_set(&tmp_links, cset, root_cgrp); | |
96d365e0 | 1834 | up_write(&css_set_rwsem); |
ddbcc7e8 | 1835 | |
d5c419b6 | 1836 | BUG_ON(!list_empty(&root_cgrp->self.children)); |
3c9c825b | 1837 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1838 | |
2bd59d48 | 1839 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1840 | ret = 0; |
2bd59d48 | 1841 | goto out; |
d427dfeb | 1842 | |
2bd59d48 TH |
1843 | destroy_root: |
1844 | kernfs_destroy_root(root->kf_root); | |
1845 | root->kf_root = NULL; | |
1846 | exit_root_id: | |
d427dfeb | 1847 | cgroup_exit_root_id(root); |
9d755d33 | 1848 | cancel_ref: |
9a1049da | 1849 | percpu_ref_exit(&root_cgrp->self.refcnt); |
2bd59d48 | 1850 | out: |
d427dfeb TH |
1851 | free_cgrp_cset_links(&tmp_links); |
1852 | return ret; | |
ddbcc7e8 PM |
1853 | } |
1854 | ||
f7e83571 | 1855 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1856 | int flags, const char *unused_dev_name, |
f7e83571 | 1857 | void *data) |
ddbcc7e8 | 1858 | { |
3a32bd72 | 1859 | struct super_block *pinned_sb = NULL; |
970317aa | 1860 | struct cgroup_subsys *ss; |
3dd06ffa | 1861 | struct cgroup_root *root; |
ddbcc7e8 | 1862 | struct cgroup_sb_opts opts; |
2bd59d48 | 1863 | struct dentry *dentry; |
8e30e2b8 | 1864 | int ret; |
970317aa | 1865 | int i; |
c6b3d5bc | 1866 | bool new_sb; |
ddbcc7e8 | 1867 | |
56fde9e0 TH |
1868 | /* |
1869 | * The first time anyone tries to mount a cgroup, enable the list | |
1870 | * linking each css_set to its tasks and fix up all existing tasks. | |
1871 | */ | |
1872 | if (!use_task_css_set_links) | |
1873 | cgroup_enable_task_cg_lists(); | |
e37a06f1 | 1874 | |
aae8aab4 | 1875 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
1876 | |
1877 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 1878 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 1879 | if (ret) |
8e30e2b8 | 1880 | goto out_unlock; |
a015edd2 | 1881 | |
2bd59d48 | 1882 | /* look for a matching existing root */ |
7b9a6ba5 | 1883 | if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) { |
a2dd4247 TH |
1884 | cgrp_dfl_root_visible = true; |
1885 | root = &cgrp_dfl_root; | |
1886 | cgroup_get(&root->cgrp); | |
1887 | ret = 0; | |
1888 | goto out_unlock; | |
ddbcc7e8 PM |
1889 | } |
1890 | ||
970317aa LZ |
1891 | /* |
1892 | * Destruction of cgroup root is asynchronous, so subsystems may | |
1893 | * still be dying after the previous unmount. Let's drain the | |
1894 | * dying subsystems. We just need to ensure that the ones | |
1895 | * unmounted previously finish dying and don't care about new ones | |
1896 | * starting. Testing ref liveliness is good enough. | |
1897 | */ | |
1898 | for_each_subsys(ss, i) { | |
1899 | if (!(opts.subsys_mask & (1 << i)) || | |
1900 | ss->root == &cgrp_dfl_root) | |
1901 | continue; | |
1902 | ||
1903 | if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { | |
1904 | mutex_unlock(&cgroup_mutex); | |
1905 | msleep(10); | |
1906 | ret = restart_syscall(); | |
1907 | goto out_free; | |
1908 | } | |
1909 | cgroup_put(&ss->root->cgrp); | |
1910 | } | |
1911 | ||
985ed670 | 1912 | for_each_root(root) { |
2bd59d48 | 1913 | bool name_match = false; |
3126121f | 1914 | |
3dd06ffa | 1915 | if (root == &cgrp_dfl_root) |
985ed670 | 1916 | continue; |
3126121f | 1917 | |
cf5d5941 | 1918 | /* |
2bd59d48 TH |
1919 | * If we asked for a name then it must match. Also, if |
1920 | * name matches but sybsys_mask doesn't, we should fail. | |
1921 | * Remember whether name matched. | |
cf5d5941 | 1922 | */ |
2bd59d48 TH |
1923 | if (opts.name) { |
1924 | if (strcmp(opts.name, root->name)) | |
1925 | continue; | |
1926 | name_match = true; | |
1927 | } | |
ddbcc7e8 | 1928 | |
c6d57f33 | 1929 | /* |
2bd59d48 TH |
1930 | * If we asked for subsystems (or explicitly for no |
1931 | * subsystems) then they must match. | |
c6d57f33 | 1932 | */ |
2bd59d48 | 1933 | if ((opts.subsys_mask || opts.none) && |
f392e51c | 1934 | (opts.subsys_mask != root->subsys_mask)) { |
2bd59d48 TH |
1935 | if (!name_match) |
1936 | continue; | |
1937 | ret = -EBUSY; | |
1938 | goto out_unlock; | |
1939 | } | |
873fe09e | 1940 | |
7b9a6ba5 TH |
1941 | if (root->flags ^ opts.flags) |
1942 | pr_warn("new mount options do not match the existing superblock, will be ignored\n"); | |
ddbcc7e8 | 1943 | |
776f02fa | 1944 | /* |
3a32bd72 LZ |
1945 | * We want to reuse @root whose lifetime is governed by its |
1946 | * ->cgrp. Let's check whether @root is alive and keep it | |
1947 | * that way. As cgroup_kill_sb() can happen anytime, we | |
1948 | * want to block it by pinning the sb so that @root doesn't | |
1949 | * get killed before mount is complete. | |
1950 | * | |
1951 | * With the sb pinned, tryget_live can reliably indicate | |
1952 | * whether @root can be reused. If it's being killed, | |
1953 | * drain it. We can use wait_queue for the wait but this | |
1954 | * path is super cold. Let's just sleep a bit and retry. | |
776f02fa | 1955 | */ |
3a32bd72 LZ |
1956 | pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
1957 | if (IS_ERR(pinned_sb) || | |
1958 | !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { | |
776f02fa | 1959 | mutex_unlock(&cgroup_mutex); |
3a32bd72 LZ |
1960 | if (!IS_ERR_OR_NULL(pinned_sb)) |
1961 | deactivate_super(pinned_sb); | |
776f02fa | 1962 | msleep(10); |
a015edd2 TH |
1963 | ret = restart_syscall(); |
1964 | goto out_free; | |
776f02fa | 1965 | } |
ddbcc7e8 | 1966 | |
776f02fa | 1967 | ret = 0; |
2bd59d48 | 1968 | goto out_unlock; |
ddbcc7e8 | 1969 | } |
ddbcc7e8 | 1970 | |
817929ec | 1971 | /* |
172a2c06 TH |
1972 | * No such thing, create a new one. name= matching without subsys |
1973 | * specification is allowed for already existing hierarchies but we | |
1974 | * can't create new one without subsys specification. | |
817929ec | 1975 | */ |
172a2c06 TH |
1976 | if (!opts.subsys_mask && !opts.none) { |
1977 | ret = -EINVAL; | |
1978 | goto out_unlock; | |
817929ec | 1979 | } |
817929ec | 1980 | |
172a2c06 TH |
1981 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
1982 | if (!root) { | |
1983 | ret = -ENOMEM; | |
2bd59d48 | 1984 | goto out_unlock; |
839ec545 | 1985 | } |
e5f6a860 | 1986 | |
172a2c06 TH |
1987 | init_cgroup_root(root, &opts); |
1988 | ||
35585573 | 1989 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
1990 | if (ret) |
1991 | cgroup_free_root(root); | |
fa3ca07e | 1992 | |
8e30e2b8 | 1993 | out_unlock: |
ddbcc7e8 | 1994 | mutex_unlock(&cgroup_mutex); |
a015edd2 | 1995 | out_free: |
c6d57f33 PM |
1996 | kfree(opts.release_agent); |
1997 | kfree(opts.name); | |
03b1cde6 | 1998 | |
2bd59d48 | 1999 | if (ret) |
8e30e2b8 | 2000 | return ERR_PTR(ret); |
2bd59d48 | 2001 | |
c9482a5b JZ |
2002 | dentry = kernfs_mount(fs_type, flags, root->kf_root, |
2003 | CGROUP_SUPER_MAGIC, &new_sb); | |
c6b3d5bc | 2004 | if (IS_ERR(dentry) || !new_sb) |
3dd06ffa | 2005 | cgroup_put(&root->cgrp); |
3a32bd72 LZ |
2006 | |
2007 | /* | |
2008 | * If @pinned_sb, we're reusing an existing root and holding an | |
2009 | * extra ref on its sb. Mount is complete. Put the extra ref. | |
2010 | */ | |
2011 | if (pinned_sb) { | |
2012 | WARN_ON(new_sb); | |
2013 | deactivate_super(pinned_sb); | |
2014 | } | |
2015 | ||
2bd59d48 TH |
2016 | return dentry; |
2017 | } | |
2018 | ||
2019 | static void cgroup_kill_sb(struct super_block *sb) | |
2020 | { | |
2021 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 2022 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 2023 | |
9d755d33 TH |
2024 | /* |
2025 | * If @root doesn't have any mounts or children, start killing it. | |
2026 | * This prevents new mounts by disabling percpu_ref_tryget_live(). | |
2027 | * cgroup_mount() may wait for @root's release. | |
1f779fb2 LZ |
2028 | * |
2029 | * And don't kill the default root. | |
9d755d33 | 2030 | */ |
3c606d35 | 2031 | if (!list_empty(&root->cgrp.self.children) || |
1f779fb2 | 2032 | root == &cgrp_dfl_root) |
9d755d33 TH |
2033 | cgroup_put(&root->cgrp); |
2034 | else | |
2035 | percpu_ref_kill(&root->cgrp.self.refcnt); | |
2036 | ||
2bd59d48 | 2037 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
2038 | } |
2039 | ||
2040 | static struct file_system_type cgroup_fs_type = { | |
2041 | .name = "cgroup", | |
f7e83571 | 2042 | .mount = cgroup_mount, |
ddbcc7e8 PM |
2043 | .kill_sb = cgroup_kill_sb, |
2044 | }; | |
2045 | ||
857a2beb | 2046 | /** |
913ffdb5 | 2047 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 2048 | * @task: target task |
857a2beb TH |
2049 | * @buf: the buffer to write the path into |
2050 | * @buflen: the length of the buffer | |
2051 | * | |
913ffdb5 TH |
2052 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
2053 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
2054 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
2055 | * cgroup controller callbacks. | |
2056 | * | |
e61734c5 | 2057 | * Return value is the same as kernfs_path(). |
857a2beb | 2058 | */ |
e61734c5 | 2059 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 2060 | { |
3dd06ffa | 2061 | struct cgroup_root *root; |
913ffdb5 | 2062 | struct cgroup *cgrp; |
e61734c5 TH |
2063 | int hierarchy_id = 1; |
2064 | char *path = NULL; | |
857a2beb TH |
2065 | |
2066 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 2067 | down_read(&css_set_rwsem); |
857a2beb | 2068 | |
913ffdb5 TH |
2069 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
2070 | ||
857a2beb TH |
2071 | if (root) { |
2072 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 2073 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
2074 | } else { |
2075 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
2076 | if (strlcpy(buf, "/", buflen) < buflen) |
2077 | path = buf; | |
857a2beb TH |
2078 | } |
2079 | ||
96d365e0 | 2080 | up_read(&css_set_rwsem); |
857a2beb | 2081 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 2082 | return path; |
857a2beb | 2083 | } |
913ffdb5 | 2084 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 2085 | |
b3dc094e | 2086 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 2087 | struct cgroup_taskset { |
b3dc094e TH |
2088 | /* the src and dst cset list running through cset->mg_node */ |
2089 | struct list_head src_csets; | |
2090 | struct list_head dst_csets; | |
2091 | ||
2092 | /* | |
2093 | * Fields for cgroup_taskset_*() iteration. | |
2094 | * | |
2095 | * Before migration is committed, the target migration tasks are on | |
2096 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
2097 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
2098 | * or ->dst_csets depending on whether migration is committed. | |
2099 | * | |
2100 | * ->cur_csets and ->cur_task point to the current task position | |
2101 | * during iteration. | |
2102 | */ | |
2103 | struct list_head *csets; | |
2104 | struct css_set *cur_cset; | |
2105 | struct task_struct *cur_task; | |
2f7ee569 TH |
2106 | }; |
2107 | ||
2108 | /** | |
2109 | * cgroup_taskset_first - reset taskset and return the first task | |
2110 | * @tset: taskset of interest | |
2111 | * | |
2112 | * @tset iteration is initialized and the first task is returned. | |
2113 | */ | |
2114 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
2115 | { | |
b3dc094e TH |
2116 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
2117 | tset->cur_task = NULL; | |
2118 | ||
2119 | return cgroup_taskset_next(tset); | |
2f7ee569 | 2120 | } |
2f7ee569 TH |
2121 | |
2122 | /** | |
2123 | * cgroup_taskset_next - iterate to the next task in taskset | |
2124 | * @tset: taskset of interest | |
2125 | * | |
2126 | * Return the next task in @tset. Iteration must have been initialized | |
2127 | * with cgroup_taskset_first(). | |
2128 | */ | |
2129 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
2130 | { | |
b3dc094e TH |
2131 | struct css_set *cset = tset->cur_cset; |
2132 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 2133 | |
b3dc094e TH |
2134 | while (&cset->mg_node != tset->csets) { |
2135 | if (!task) | |
2136 | task = list_first_entry(&cset->mg_tasks, | |
2137 | struct task_struct, cg_list); | |
2138 | else | |
2139 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 2140 | |
b3dc094e TH |
2141 | if (&task->cg_list != &cset->mg_tasks) { |
2142 | tset->cur_cset = cset; | |
2143 | tset->cur_task = task; | |
2144 | return task; | |
2145 | } | |
2f7ee569 | 2146 | |
b3dc094e TH |
2147 | cset = list_next_entry(cset, mg_node); |
2148 | task = NULL; | |
2149 | } | |
2f7ee569 | 2150 | |
b3dc094e | 2151 | return NULL; |
2f7ee569 | 2152 | } |
2f7ee569 | 2153 | |
cb0f1fe9 | 2154 | /** |
74a1166d | 2155 | * cgroup_task_migrate - move a task from one cgroup to another. |
60106946 | 2156 | * @old_cgrp: the cgroup @tsk is being migrated from |
cb0f1fe9 TH |
2157 | * @tsk: the task being migrated |
2158 | * @new_cset: the new css_set @tsk is being attached to | |
74a1166d | 2159 | * |
cb0f1fe9 | 2160 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. |
74a1166d | 2161 | */ |
5abb8855 TH |
2162 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
2163 | struct task_struct *tsk, | |
2164 | struct css_set *new_cset) | |
74a1166d | 2165 | { |
5abb8855 | 2166 | struct css_set *old_cset; |
74a1166d | 2167 | |
cb0f1fe9 TH |
2168 | lockdep_assert_held(&cgroup_mutex); |
2169 | lockdep_assert_held(&css_set_rwsem); | |
2170 | ||
74a1166d | 2171 | /* |
1ed13287 TH |
2172 | * We are synchronized through cgroup_threadgroup_rwsem against |
2173 | * PF_EXITING setting such that we can't race against cgroup_exit() | |
2174 | * changing the css_set to init_css_set and dropping the old one. | |
74a1166d | 2175 | */ |
c84cdf75 | 2176 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 2177 | old_cset = task_css_set(tsk); |
74a1166d | 2178 | |
b3dc094e | 2179 | get_css_set(new_cset); |
5abb8855 | 2180 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d | 2181 | |
1b9aba49 TH |
2182 | /* |
2183 | * Use move_tail so that cgroup_taskset_first() still returns the | |
2184 | * leader after migration. This works because cgroup_migrate() | |
2185 | * ensures that the dst_cset of the leader is the first on the | |
2186 | * tset's dst_csets list. | |
2187 | */ | |
2188 | list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); | |
74a1166d BB |
2189 | |
2190 | /* | |
5abb8855 TH |
2191 | * We just gained a reference on old_cset by taking it from the |
2192 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
2193 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 2194 | */ |
a25eb52e | 2195 | put_css_set_locked(old_cset); |
74a1166d BB |
2196 | } |
2197 | ||
a043e3b2 | 2198 | /** |
1958d2d5 TH |
2199 | * cgroup_migrate_finish - cleanup after attach |
2200 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 2201 | * |
1958d2d5 TH |
2202 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
2203 | * those functions for details. | |
74a1166d | 2204 | */ |
1958d2d5 | 2205 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 2206 | { |
1958d2d5 | 2207 | struct css_set *cset, *tmp_cset; |
74a1166d | 2208 | |
1958d2d5 TH |
2209 | lockdep_assert_held(&cgroup_mutex); |
2210 | ||
2211 | down_write(&css_set_rwsem); | |
2212 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { | |
2213 | cset->mg_src_cgrp = NULL; | |
2214 | cset->mg_dst_cset = NULL; | |
2215 | list_del_init(&cset->mg_preload_node); | |
a25eb52e | 2216 | put_css_set_locked(cset); |
1958d2d5 TH |
2217 | } |
2218 | up_write(&css_set_rwsem); | |
2219 | } | |
2220 | ||
2221 | /** | |
2222 | * cgroup_migrate_add_src - add a migration source css_set | |
2223 | * @src_cset: the source css_set to add | |
2224 | * @dst_cgrp: the destination cgroup | |
2225 | * @preloaded_csets: list of preloaded css_sets | |
2226 | * | |
2227 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
2228 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
2229 | * up by cgroup_migrate_finish(). | |
2230 | * | |
1ed13287 TH |
2231 | * This function may be called without holding cgroup_threadgroup_rwsem |
2232 | * even if the target is a process. Threads may be created and destroyed | |
2233 | * but as long as cgroup_mutex is not dropped, no new css_set can be put | |
2234 | * into play and the preloaded css_sets are guaranteed to cover all | |
2235 | * migrations. | |
1958d2d5 TH |
2236 | */ |
2237 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
2238 | struct cgroup *dst_cgrp, | |
2239 | struct list_head *preloaded_csets) | |
2240 | { | |
2241 | struct cgroup *src_cgrp; | |
2242 | ||
2243 | lockdep_assert_held(&cgroup_mutex); | |
2244 | lockdep_assert_held(&css_set_rwsem); | |
2245 | ||
2246 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
2247 | ||
1958d2d5 TH |
2248 | if (!list_empty(&src_cset->mg_preload_node)) |
2249 | return; | |
2250 | ||
2251 | WARN_ON(src_cset->mg_src_cgrp); | |
2252 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
2253 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
2254 | ||
2255 | src_cset->mg_src_cgrp = src_cgrp; | |
2256 | get_css_set(src_cset); | |
2257 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
2258 | } | |
2259 | ||
2260 | /** | |
2261 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
f817de98 | 2262 | * @dst_cgrp: the destination cgroup (may be %NULL) |
1958d2d5 TH |
2263 | * @preloaded_csets: list of preloaded source css_sets |
2264 | * | |
2265 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
2266 | * have been preloaded to @preloaded_csets. This function looks up and | |
f817de98 TH |
2267 | * pins all destination css_sets, links each to its source, and append them |
2268 | * to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each | |
2269 | * source css_set is assumed to be its cgroup on the default hierarchy. | |
1958d2d5 TH |
2270 | * |
2271 | * This function must be called after cgroup_migrate_add_src() has been | |
2272 | * called on each migration source css_set. After migration is performed | |
2273 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
2274 | * @preloaded_csets. | |
2275 | */ | |
2276 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
2277 | struct list_head *preloaded_csets) | |
2278 | { | |
2279 | LIST_HEAD(csets); | |
f817de98 | 2280 | struct css_set *src_cset, *tmp_cset; |
1958d2d5 TH |
2281 | |
2282 | lockdep_assert_held(&cgroup_mutex); | |
2283 | ||
f8f22e53 TH |
2284 | /* |
2285 | * Except for the root, child_subsys_mask must be zero for a cgroup | |
2286 | * with tasks so that child cgroups don't compete against tasks. | |
2287 | */ | |
d51f39b0 | 2288 | if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && |
f8f22e53 TH |
2289 | dst_cgrp->child_subsys_mask) |
2290 | return -EBUSY; | |
2291 | ||
1958d2d5 | 2292 | /* look up the dst cset for each src cset and link it to src */ |
f817de98 | 2293 | list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { |
1958d2d5 TH |
2294 | struct css_set *dst_cset; |
2295 | ||
f817de98 TH |
2296 | dst_cset = find_css_set(src_cset, |
2297 | dst_cgrp ?: src_cset->dfl_cgrp); | |
1958d2d5 TH |
2298 | if (!dst_cset) |
2299 | goto err; | |
2300 | ||
2301 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
f817de98 TH |
2302 | |
2303 | /* | |
2304 | * If src cset equals dst, it's noop. Drop the src. | |
2305 | * cgroup_migrate() will skip the cset too. Note that we | |
2306 | * can't handle src == dst as some nodes are used by both. | |
2307 | */ | |
2308 | if (src_cset == dst_cset) { | |
2309 | src_cset->mg_src_cgrp = NULL; | |
2310 | list_del_init(&src_cset->mg_preload_node); | |
a25eb52e ZL |
2311 | put_css_set(src_cset); |
2312 | put_css_set(dst_cset); | |
f817de98 TH |
2313 | continue; |
2314 | } | |
2315 | ||
1958d2d5 TH |
2316 | src_cset->mg_dst_cset = dst_cset; |
2317 | ||
2318 | if (list_empty(&dst_cset->mg_preload_node)) | |
2319 | list_add(&dst_cset->mg_preload_node, &csets); | |
2320 | else | |
a25eb52e | 2321 | put_css_set(dst_cset); |
1958d2d5 TH |
2322 | } |
2323 | ||
f817de98 | 2324 | list_splice_tail(&csets, preloaded_csets); |
1958d2d5 TH |
2325 | return 0; |
2326 | err: | |
2327 | cgroup_migrate_finish(&csets); | |
2328 | return -ENOMEM; | |
2329 | } | |
2330 | ||
2331 | /** | |
2332 | * cgroup_migrate - migrate a process or task to a cgroup | |
2333 | * @cgrp: the destination cgroup | |
2334 | * @leader: the leader of the process or the task to migrate | |
2335 | * @threadgroup: whether @leader points to the whole process or a single task | |
2336 | * | |
2337 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1ed13287 | 2338 | * process, the caller must be holding cgroup_threadgroup_rwsem. The |
1958d2d5 TH |
2339 | * caller is also responsible for invoking cgroup_migrate_add_src() and |
2340 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
2341 | * function and following up with cgroup_migrate_finish(). | |
2342 | * | |
2343 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
2344 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
2345 | * failure, when migrating multiple targets, the success or failure can be | |
2346 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
2347 | * actually starting migrating. | |
2348 | */ | |
2349 | static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader, | |
2350 | bool threadgroup) | |
74a1166d | 2351 | { |
b3dc094e TH |
2352 | struct cgroup_taskset tset = { |
2353 | .src_csets = LIST_HEAD_INIT(tset.src_csets), | |
2354 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), | |
2355 | .csets = &tset.src_csets, | |
2356 | }; | |
1c6727af | 2357 | struct cgroup_subsys_state *css, *failed_css = NULL; |
b3dc094e TH |
2358 | struct css_set *cset, *tmp_cset; |
2359 | struct task_struct *task, *tmp_task; | |
2360 | int i, ret; | |
74a1166d | 2361 | |
fb5d2b4c MSB |
2362 | /* |
2363 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2364 | * already PF_EXITING could be freed from underneath us unless we | |
2365 | * take an rcu_read_lock. | |
2366 | */ | |
b3dc094e | 2367 | down_write(&css_set_rwsem); |
fb5d2b4c | 2368 | rcu_read_lock(); |
9db8de37 | 2369 | task = leader; |
74a1166d | 2370 | do { |
9db8de37 TH |
2371 | /* @task either already exited or can't exit until the end */ |
2372 | if (task->flags & PF_EXITING) | |
ea84753c | 2373 | goto next; |
134d3373 | 2374 | |
eaf797ab TH |
2375 | /* leave @task alone if post_fork() hasn't linked it yet */ |
2376 | if (list_empty(&task->cg_list)) | |
ea84753c | 2377 | goto next; |
cd3d0952 | 2378 | |
b3dc094e | 2379 | cset = task_css_set(task); |
1958d2d5 | 2380 | if (!cset->mg_src_cgrp) |
ea84753c | 2381 | goto next; |
b3dc094e | 2382 | |
61d1d219 | 2383 | /* |
1b9aba49 TH |
2384 | * cgroup_taskset_first() must always return the leader. |
2385 | * Take care to avoid disturbing the ordering. | |
61d1d219 | 2386 | */ |
1b9aba49 TH |
2387 | list_move_tail(&task->cg_list, &cset->mg_tasks); |
2388 | if (list_empty(&cset->mg_node)) | |
2389 | list_add_tail(&cset->mg_node, &tset.src_csets); | |
2390 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
2391 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
2392 | &tset.dst_csets); | |
ea84753c | 2393 | next: |
081aa458 LZ |
2394 | if (!threadgroup) |
2395 | break; | |
9db8de37 | 2396 | } while_each_thread(leader, task); |
fb5d2b4c | 2397 | rcu_read_unlock(); |
b3dc094e | 2398 | up_write(&css_set_rwsem); |
74a1166d | 2399 | |
134d3373 | 2400 | /* methods shouldn't be called if no task is actually migrating */ |
b3dc094e TH |
2401 | if (list_empty(&tset.src_csets)) |
2402 | return 0; | |
134d3373 | 2403 | |
1958d2d5 | 2404 | /* check that we can legitimately attach to the cgroup */ |
aec3dfcb | 2405 | for_each_e_css(css, i, cgrp) { |
1c6727af | 2406 | if (css->ss->can_attach) { |
9db8de37 TH |
2407 | ret = css->ss->can_attach(css, &tset); |
2408 | if (ret) { | |
1c6727af | 2409 | failed_css = css; |
74a1166d BB |
2410 | goto out_cancel_attach; |
2411 | } | |
2412 | } | |
74a1166d BB |
2413 | } |
2414 | ||
2415 | /* | |
1958d2d5 TH |
2416 | * Now that we're guaranteed success, proceed to move all tasks to |
2417 | * the new cgroup. There are no failure cases after here, so this | |
2418 | * is the commit point. | |
74a1166d | 2419 | */ |
cb0f1fe9 | 2420 | down_write(&css_set_rwsem); |
b3dc094e TH |
2421 | list_for_each_entry(cset, &tset.src_csets, mg_node) { |
2422 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) | |
2423 | cgroup_task_migrate(cset->mg_src_cgrp, task, | |
2424 | cset->mg_dst_cset); | |
74a1166d | 2425 | } |
cb0f1fe9 | 2426 | up_write(&css_set_rwsem); |
74a1166d BB |
2427 | |
2428 | /* | |
1958d2d5 TH |
2429 | * Migration is committed, all target tasks are now on dst_csets. |
2430 | * Nothing is sensitive to fork() after this point. Notify | |
2431 | * controllers that migration is complete. | |
74a1166d | 2432 | */ |
1958d2d5 | 2433 | tset.csets = &tset.dst_csets; |
74a1166d | 2434 | |
aec3dfcb | 2435 | for_each_e_css(css, i, cgrp) |
1c6727af TH |
2436 | if (css->ss->attach) |
2437 | css->ss->attach(css, &tset); | |
74a1166d | 2438 | |
9db8de37 | 2439 | ret = 0; |
b3dc094e TH |
2440 | goto out_release_tset; |
2441 | ||
74a1166d | 2442 | out_cancel_attach: |
aec3dfcb | 2443 | for_each_e_css(css, i, cgrp) { |
b3dc094e TH |
2444 | if (css == failed_css) |
2445 | break; | |
2446 | if (css->ss->cancel_attach) | |
2447 | css->ss->cancel_attach(css, &tset); | |
74a1166d | 2448 | } |
b3dc094e TH |
2449 | out_release_tset: |
2450 | down_write(&css_set_rwsem); | |
2451 | list_splice_init(&tset.dst_csets, &tset.src_csets); | |
2452 | list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) { | |
1b9aba49 | 2453 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
b3dc094e | 2454 | list_del_init(&cset->mg_node); |
b3dc094e TH |
2455 | } |
2456 | up_write(&css_set_rwsem); | |
9db8de37 | 2457 | return ret; |
74a1166d BB |
2458 | } |
2459 | ||
1958d2d5 TH |
2460 | /** |
2461 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2462 | * @dst_cgrp: the cgroup to attach to | |
2463 | * @leader: the task or the leader of the threadgroup to be attached | |
2464 | * @threadgroup: attach the whole threadgroup? | |
2465 | * | |
1ed13287 | 2466 | * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
1958d2d5 TH |
2467 | */ |
2468 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2469 | struct task_struct *leader, bool threadgroup) | |
2470 | { | |
2471 | LIST_HEAD(preloaded_csets); | |
2472 | struct task_struct *task; | |
2473 | int ret; | |
2474 | ||
2475 | /* look up all src csets */ | |
2476 | down_read(&css_set_rwsem); | |
2477 | rcu_read_lock(); | |
2478 | task = leader; | |
2479 | do { | |
2480 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2481 | &preloaded_csets); | |
2482 | if (!threadgroup) | |
2483 | break; | |
2484 | } while_each_thread(leader, task); | |
2485 | rcu_read_unlock(); | |
2486 | up_read(&css_set_rwsem); | |
2487 | ||
2488 | /* prepare dst csets and commit */ | |
2489 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2490 | if (!ret) | |
2491 | ret = cgroup_migrate(dst_cgrp, leader, threadgroup); | |
2492 | ||
2493 | cgroup_migrate_finish(&preloaded_csets); | |
2494 | return ret; | |
74a1166d BB |
2495 | } |
2496 | ||
187fe840 TH |
2497 | static int cgroup_procs_write_permission(struct task_struct *task, |
2498 | struct cgroup *dst_cgrp, | |
2499 | struct kernfs_open_file *of) | |
dedf22e9 TH |
2500 | { |
2501 | const struct cred *cred = current_cred(); | |
2502 | const struct cred *tcred = get_task_cred(task); | |
2503 | int ret = 0; | |
2504 | ||
2505 | /* | |
2506 | * even if we're attaching all tasks in the thread group, we only | |
2507 | * need to check permissions on one of them. | |
2508 | */ | |
2509 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && | |
2510 | !uid_eq(cred->euid, tcred->uid) && | |
2511 | !uid_eq(cred->euid, tcred->suid)) | |
2512 | ret = -EACCES; | |
2513 | ||
187fe840 TH |
2514 | if (!ret && cgroup_on_dfl(dst_cgrp)) { |
2515 | struct super_block *sb = of->file->f_path.dentry->d_sb; | |
2516 | struct cgroup *cgrp; | |
2517 | struct inode *inode; | |
2518 | ||
2519 | down_read(&css_set_rwsem); | |
2520 | cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); | |
2521 | up_read(&css_set_rwsem); | |
2522 | ||
2523 | while (!cgroup_is_descendant(dst_cgrp, cgrp)) | |
2524 | cgrp = cgroup_parent(cgrp); | |
2525 | ||
2526 | ret = -ENOMEM; | |
2527 | inode = kernfs_get_inode(sb, cgrp->procs_kn); | |
2528 | if (inode) { | |
2529 | ret = inode_permission(inode, MAY_WRITE); | |
2530 | iput(inode); | |
2531 | } | |
2532 | } | |
2533 | ||
dedf22e9 TH |
2534 | put_cred(tcred); |
2535 | return ret; | |
2536 | } | |
2537 | ||
74a1166d BB |
2538 | /* |
2539 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2540 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2541 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2542 | */ |
acbef755 TH |
2543 | static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
2544 | size_t nbytes, loff_t off, bool threadgroup) | |
bbcb81d0 | 2545 | { |
bbcb81d0 | 2546 | struct task_struct *tsk; |
e76ecaee | 2547 | struct cgroup *cgrp; |
acbef755 | 2548 | pid_t pid; |
bbcb81d0 PM |
2549 | int ret; |
2550 | ||
acbef755 TH |
2551 | if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
2552 | return -EINVAL; | |
2553 | ||
e76ecaee TH |
2554 | cgrp = cgroup_kn_lock_live(of->kn); |
2555 | if (!cgrp) | |
74a1166d BB |
2556 | return -ENODEV; |
2557 | ||
3014dde7 | 2558 | percpu_down_write(&cgroup_threadgroup_rwsem); |
b78949eb | 2559 | rcu_read_lock(); |
bbcb81d0 | 2560 | if (pid) { |
73507f33 | 2561 | tsk = find_task_by_vpid(pid); |
74a1166d | 2562 | if (!tsk) { |
dd4b0a46 | 2563 | ret = -ESRCH; |
3014dde7 | 2564 | goto out_unlock_rcu; |
bbcb81d0 | 2565 | } |
dedf22e9 | 2566 | } else { |
b78949eb | 2567 | tsk = current; |
dedf22e9 | 2568 | } |
cd3d0952 TH |
2569 | |
2570 | if (threadgroup) | |
b78949eb | 2571 | tsk = tsk->group_leader; |
c4c27fbd MG |
2572 | |
2573 | /* | |
14a40ffc | 2574 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2575 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2576 | * with no rt_runtime allocated. Just say no. | |
2577 | */ | |
14a40ffc | 2578 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd | 2579 | ret = -EINVAL; |
3014dde7 | 2580 | goto out_unlock_rcu; |
c4c27fbd MG |
2581 | } |
2582 | ||
b78949eb MSB |
2583 | get_task_struct(tsk); |
2584 | rcu_read_unlock(); | |
2585 | ||
187fe840 | 2586 | ret = cgroup_procs_write_permission(tsk, cgrp, of); |
dedf22e9 TH |
2587 | if (!ret) |
2588 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
081aa458 | 2589 | |
f9f9e7b7 | 2590 | put_task_struct(tsk); |
3014dde7 TH |
2591 | goto out_unlock_threadgroup; |
2592 | ||
2593 | out_unlock_rcu: | |
2594 | rcu_read_unlock(); | |
2595 | out_unlock_threadgroup: | |
2596 | percpu_up_write(&cgroup_threadgroup_rwsem); | |
e76ecaee | 2597 | cgroup_kn_unlock(of->kn); |
acbef755 | 2598 | return ret ?: nbytes; |
bbcb81d0 PM |
2599 | } |
2600 | ||
7ae1bad9 TH |
2601 | /** |
2602 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2603 | * @from: attach to all cgroups of a given task | |
2604 | * @tsk: the task to be attached | |
2605 | */ | |
2606 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2607 | { | |
3dd06ffa | 2608 | struct cgroup_root *root; |
7ae1bad9 TH |
2609 | int retval = 0; |
2610 | ||
47cfcd09 | 2611 | mutex_lock(&cgroup_mutex); |
985ed670 | 2612 | for_each_root(root) { |
96d365e0 TH |
2613 | struct cgroup *from_cgrp; |
2614 | ||
3dd06ffa | 2615 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2616 | continue; |
2617 | ||
96d365e0 TH |
2618 | down_read(&css_set_rwsem); |
2619 | from_cgrp = task_cgroup_from_root(from, root); | |
2620 | up_read(&css_set_rwsem); | |
7ae1bad9 | 2621 | |
6f4b7e63 | 2622 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2623 | if (retval) |
2624 | break; | |
2625 | } | |
47cfcd09 | 2626 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2627 | |
2628 | return retval; | |
2629 | } | |
2630 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2631 | ||
acbef755 TH |
2632 | static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
2633 | char *buf, size_t nbytes, loff_t off) | |
74a1166d | 2634 | { |
acbef755 | 2635 | return __cgroup_procs_write(of, buf, nbytes, off, false); |
74a1166d BB |
2636 | } |
2637 | ||
acbef755 TH |
2638 | static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
2639 | char *buf, size_t nbytes, loff_t off) | |
af351026 | 2640 | { |
acbef755 | 2641 | return __cgroup_procs_write(of, buf, nbytes, off, true); |
af351026 PM |
2642 | } |
2643 | ||
451af504 TH |
2644 | static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
2645 | char *buf, size_t nbytes, loff_t off) | |
e788e066 | 2646 | { |
e76ecaee | 2647 | struct cgroup *cgrp; |
5f469907 | 2648 | |
e76ecaee | 2649 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
5f469907 | 2650 | |
e76ecaee TH |
2651 | cgrp = cgroup_kn_lock_live(of->kn); |
2652 | if (!cgrp) | |
e788e066 | 2653 | return -ENODEV; |
69e943b7 | 2654 | spin_lock(&release_agent_path_lock); |
e76ecaee TH |
2655 | strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
2656 | sizeof(cgrp->root->release_agent_path)); | |
69e943b7 | 2657 | spin_unlock(&release_agent_path_lock); |
e76ecaee | 2658 | cgroup_kn_unlock(of->kn); |
451af504 | 2659 | return nbytes; |
e788e066 PM |
2660 | } |
2661 | ||
2da8ca82 | 2662 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2663 | { |
2da8ca82 | 2664 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2665 | |
46cfeb04 | 2666 | spin_lock(&release_agent_path_lock); |
e788e066 | 2667 | seq_puts(seq, cgrp->root->release_agent_path); |
46cfeb04 | 2668 | spin_unlock(&release_agent_path_lock); |
e788e066 | 2669 | seq_putc(seq, '\n'); |
e788e066 PM |
2670 | return 0; |
2671 | } | |
2672 | ||
2da8ca82 | 2673 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2674 | { |
c1d5d42e | 2675 | seq_puts(seq, "0\n"); |
e788e066 PM |
2676 | return 0; |
2677 | } | |
2678 | ||
8ab456ac | 2679 | static void cgroup_print_ss_mask(struct seq_file *seq, unsigned long ss_mask) |
355e0c48 | 2680 | { |
f8f22e53 TH |
2681 | struct cgroup_subsys *ss; |
2682 | bool printed = false; | |
2683 | int ssid; | |
a742c59d | 2684 | |
a966a4ed AS |
2685 | for_each_subsys_which(ss, ssid, &ss_mask) { |
2686 | if (printed) | |
2687 | seq_putc(seq, ' '); | |
2688 | seq_printf(seq, "%s", ss->name); | |
2689 | printed = true; | |
e73d2c61 | 2690 | } |
f8f22e53 TH |
2691 | if (printed) |
2692 | seq_putc(seq, '\n'); | |
355e0c48 PM |
2693 | } |
2694 | ||
f8f22e53 TH |
2695 | /* show controllers which are currently attached to the default hierarchy */ |
2696 | static int cgroup_root_controllers_show(struct seq_file *seq, void *v) | |
db3b1497 | 2697 | { |
f8f22e53 TH |
2698 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2699 | ||
5533e011 TH |
2700 | cgroup_print_ss_mask(seq, cgrp->root->subsys_mask & |
2701 | ~cgrp_dfl_root_inhibit_ss_mask); | |
f8f22e53 | 2702 | return 0; |
db3b1497 PM |
2703 | } |
2704 | ||
f8f22e53 TH |
2705 | /* show controllers which are enabled from the parent */ |
2706 | static int cgroup_controllers_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2707 | { |
f8f22e53 TH |
2708 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2709 | ||
667c2491 | 2710 | cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control); |
f8f22e53 | 2711 | return 0; |
ddbcc7e8 PM |
2712 | } |
2713 | ||
f8f22e53 TH |
2714 | /* show controllers which are enabled for a given cgroup's children */ |
2715 | static int cgroup_subtree_control_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2716 | { |
f8f22e53 TH |
2717 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2718 | ||
667c2491 | 2719 | cgroup_print_ss_mask(seq, cgrp->subtree_control); |
f8f22e53 TH |
2720 | return 0; |
2721 | } | |
2722 | ||
2723 | /** | |
2724 | * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy | |
2725 | * @cgrp: root of the subtree to update csses for | |
2726 | * | |
2727 | * @cgrp's child_subsys_mask has changed and its subtree's (self excluded) | |
2728 | * css associations need to be updated accordingly. This function looks up | |
2729 | * all css_sets which are attached to the subtree, creates the matching | |
2730 | * updated css_sets and migrates the tasks to the new ones. | |
2731 | */ | |
2732 | static int cgroup_update_dfl_csses(struct cgroup *cgrp) | |
2733 | { | |
2734 | LIST_HEAD(preloaded_csets); | |
2735 | struct cgroup_subsys_state *css; | |
2736 | struct css_set *src_cset; | |
2737 | int ret; | |
2738 | ||
f8f22e53 TH |
2739 | lockdep_assert_held(&cgroup_mutex); |
2740 | ||
3014dde7 TH |
2741 | percpu_down_write(&cgroup_threadgroup_rwsem); |
2742 | ||
f8f22e53 TH |
2743 | /* look up all csses currently attached to @cgrp's subtree */ |
2744 | down_read(&css_set_rwsem); | |
2745 | css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) { | |
2746 | struct cgrp_cset_link *link; | |
2747 | ||
2748 | /* self is not affected by child_subsys_mask change */ | |
2749 | if (css->cgroup == cgrp) | |
2750 | continue; | |
2751 | ||
2752 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) | |
2753 | cgroup_migrate_add_src(link->cset, cgrp, | |
2754 | &preloaded_csets); | |
2755 | } | |
2756 | up_read(&css_set_rwsem); | |
2757 | ||
2758 | /* NULL dst indicates self on default hierarchy */ | |
2759 | ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets); | |
2760 | if (ret) | |
2761 | goto out_finish; | |
2762 | ||
2763 | list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { | |
2764 | struct task_struct *last_task = NULL, *task; | |
2765 | ||
2766 | /* src_csets precede dst_csets, break on the first dst_cset */ | |
2767 | if (!src_cset->mg_src_cgrp) | |
2768 | break; | |
2769 | ||
2770 | /* | |
2771 | * All tasks in src_cset need to be migrated to the | |
2772 | * matching dst_cset. Empty it process by process. We | |
2773 | * walk tasks but migrate processes. The leader might even | |
2774 | * belong to a different cset but such src_cset would also | |
2775 | * be among the target src_csets because the default | |
2776 | * hierarchy enforces per-process membership. | |
2777 | */ | |
2778 | while (true) { | |
2779 | down_read(&css_set_rwsem); | |
2780 | task = list_first_entry_or_null(&src_cset->tasks, | |
2781 | struct task_struct, cg_list); | |
2782 | if (task) { | |
2783 | task = task->group_leader; | |
2784 | WARN_ON_ONCE(!task_css_set(task)->mg_src_cgrp); | |
2785 | get_task_struct(task); | |
2786 | } | |
2787 | up_read(&css_set_rwsem); | |
2788 | ||
2789 | if (!task) | |
2790 | break; | |
2791 | ||
2792 | /* guard against possible infinite loop */ | |
2793 | if (WARN(last_task == task, | |
2794 | "cgroup: update_dfl_csses failed to make progress, aborting in inconsistent state\n")) | |
2795 | goto out_finish; | |
2796 | last_task = task; | |
2797 | ||
f8f22e53 TH |
2798 | ret = cgroup_migrate(src_cset->dfl_cgrp, task, true); |
2799 | ||
f8f22e53 TH |
2800 | put_task_struct(task); |
2801 | ||
2802 | if (WARN(ret, "cgroup: failed to update controllers for the default hierarchy (%d), further operations may crash or hang\n", ret)) | |
2803 | goto out_finish; | |
2804 | } | |
2805 | } | |
2806 | ||
2807 | out_finish: | |
2808 | cgroup_migrate_finish(&preloaded_csets); | |
3014dde7 | 2809 | percpu_up_write(&cgroup_threadgroup_rwsem); |
f8f22e53 TH |
2810 | return ret; |
2811 | } | |
2812 | ||
2813 | /* change the enabled child controllers for a cgroup in the default hierarchy */ | |
451af504 TH |
2814 | static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
2815 | char *buf, size_t nbytes, | |
2816 | loff_t off) | |
f8f22e53 | 2817 | { |
8ab456ac AS |
2818 | unsigned long enable = 0, disable = 0; |
2819 | unsigned long css_enable, css_disable, old_sc, new_sc, old_ss, new_ss; | |
a9746d8d | 2820 | struct cgroup *cgrp, *child; |
f8f22e53 | 2821 | struct cgroup_subsys *ss; |
451af504 | 2822 | char *tok; |
f8f22e53 TH |
2823 | int ssid, ret; |
2824 | ||
2825 | /* | |
d37167ab TH |
2826 | * Parse input - space separated list of subsystem names prefixed |
2827 | * with either + or -. | |
f8f22e53 | 2828 | */ |
451af504 TH |
2829 | buf = strstrip(buf); |
2830 | while ((tok = strsep(&buf, " "))) { | |
a966a4ed AS |
2831 | unsigned long tmp_ss_mask = ~cgrp_dfl_root_inhibit_ss_mask; |
2832 | ||
d37167ab TH |
2833 | if (tok[0] == '\0') |
2834 | continue; | |
a966a4ed | 2835 | for_each_subsys_which(ss, ssid, &tmp_ss_mask) { |
fc5ed1e9 TH |
2836 | if (!cgroup_ssid_enabled(ssid) || |
2837 | strcmp(tok + 1, ss->name)) | |
f8f22e53 TH |
2838 | continue; |
2839 | ||
2840 | if (*tok == '+') { | |
7d331fa9 TH |
2841 | enable |= 1 << ssid; |
2842 | disable &= ~(1 << ssid); | |
f8f22e53 | 2843 | } else if (*tok == '-') { |
7d331fa9 TH |
2844 | disable |= 1 << ssid; |
2845 | enable &= ~(1 << ssid); | |
f8f22e53 TH |
2846 | } else { |
2847 | return -EINVAL; | |
2848 | } | |
2849 | break; | |
2850 | } | |
2851 | if (ssid == CGROUP_SUBSYS_COUNT) | |
2852 | return -EINVAL; | |
2853 | } | |
2854 | ||
a9746d8d TH |
2855 | cgrp = cgroup_kn_lock_live(of->kn); |
2856 | if (!cgrp) | |
2857 | return -ENODEV; | |
f8f22e53 TH |
2858 | |
2859 | for_each_subsys(ss, ssid) { | |
2860 | if (enable & (1 << ssid)) { | |
667c2491 | 2861 | if (cgrp->subtree_control & (1 << ssid)) { |
f8f22e53 TH |
2862 | enable &= ~(1 << ssid); |
2863 | continue; | |
2864 | } | |
2865 | ||
c29adf24 TH |
2866 | /* unavailable or not enabled on the parent? */ |
2867 | if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) || | |
2868 | (cgroup_parent(cgrp) && | |
667c2491 | 2869 | !(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) { |
c29adf24 TH |
2870 | ret = -ENOENT; |
2871 | goto out_unlock; | |
2872 | } | |
f8f22e53 | 2873 | } else if (disable & (1 << ssid)) { |
667c2491 | 2874 | if (!(cgrp->subtree_control & (1 << ssid))) { |
f8f22e53 TH |
2875 | disable &= ~(1 << ssid); |
2876 | continue; | |
2877 | } | |
2878 | ||
2879 | /* a child has it enabled? */ | |
2880 | cgroup_for_each_live_child(child, cgrp) { | |
667c2491 | 2881 | if (child->subtree_control & (1 << ssid)) { |
f8f22e53 | 2882 | ret = -EBUSY; |
ddab2b6e | 2883 | goto out_unlock; |
f8f22e53 TH |
2884 | } |
2885 | } | |
2886 | } | |
2887 | } | |
2888 | ||
2889 | if (!enable && !disable) { | |
2890 | ret = 0; | |
ddab2b6e | 2891 | goto out_unlock; |
f8f22e53 TH |
2892 | } |
2893 | ||
2894 | /* | |
667c2491 | 2895 | * Except for the root, subtree_control must be zero for a cgroup |
f8f22e53 TH |
2896 | * with tasks so that child cgroups don't compete against tasks. |
2897 | */ | |
d51f39b0 | 2898 | if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) { |
f8f22e53 TH |
2899 | ret = -EBUSY; |
2900 | goto out_unlock; | |
2901 | } | |
2902 | ||
2903 | /* | |
f63070d3 TH |
2904 | * Update subsys masks and calculate what needs to be done. More |
2905 | * subsystems than specified may need to be enabled or disabled | |
2906 | * depending on subsystem dependencies. | |
2907 | */ | |
755bf5ee TH |
2908 | old_sc = cgrp->subtree_control; |
2909 | old_ss = cgrp->child_subsys_mask; | |
2910 | new_sc = (old_sc | enable) & ~disable; | |
2911 | new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc); | |
f63070d3 | 2912 | |
755bf5ee TH |
2913 | css_enable = ~old_ss & new_ss; |
2914 | css_disable = old_ss & ~new_ss; | |
f63070d3 TH |
2915 | enable |= css_enable; |
2916 | disable |= css_disable; | |
c29adf24 | 2917 | |
db6e3053 TH |
2918 | /* |
2919 | * Because css offlining is asynchronous, userland might try to | |
2920 | * re-enable the same controller while the previous instance is | |
2921 | * still around. In such cases, wait till it's gone using | |
2922 | * offline_waitq. | |
2923 | */ | |
a966a4ed | 2924 | for_each_subsys_which(ss, ssid, &css_enable) { |
db6e3053 TH |
2925 | cgroup_for_each_live_child(child, cgrp) { |
2926 | DEFINE_WAIT(wait); | |
2927 | ||
2928 | if (!cgroup_css(child, ss)) | |
2929 | continue; | |
2930 | ||
2931 | cgroup_get(child); | |
2932 | prepare_to_wait(&child->offline_waitq, &wait, | |
2933 | TASK_UNINTERRUPTIBLE); | |
2934 | cgroup_kn_unlock(of->kn); | |
2935 | schedule(); | |
2936 | finish_wait(&child->offline_waitq, &wait); | |
2937 | cgroup_put(child); | |
2938 | ||
2939 | return restart_syscall(); | |
2940 | } | |
2941 | } | |
2942 | ||
755bf5ee TH |
2943 | cgrp->subtree_control = new_sc; |
2944 | cgrp->child_subsys_mask = new_ss; | |
2945 | ||
f63070d3 TH |
2946 | /* |
2947 | * Create new csses or make the existing ones visible. A css is | |
2948 | * created invisible if it's being implicitly enabled through | |
2949 | * dependency. An invisible css is made visible when the userland | |
2950 | * explicitly enables it. | |
f8f22e53 TH |
2951 | */ |
2952 | for_each_subsys(ss, ssid) { | |
2953 | if (!(enable & (1 << ssid))) | |
2954 | continue; | |
2955 | ||
2956 | cgroup_for_each_live_child(child, cgrp) { | |
f63070d3 TH |
2957 | if (css_enable & (1 << ssid)) |
2958 | ret = create_css(child, ss, | |
2959 | cgrp->subtree_control & (1 << ssid)); | |
2960 | else | |
2961 | ret = cgroup_populate_dir(child, 1 << ssid); | |
f8f22e53 TH |
2962 | if (ret) |
2963 | goto err_undo_css; | |
2964 | } | |
2965 | } | |
2966 | ||
c29adf24 TH |
2967 | /* |
2968 | * At this point, cgroup_e_css() results reflect the new csses | |
2969 | * making the following cgroup_update_dfl_csses() properly update | |
2970 | * css associations of all tasks in the subtree. | |
2971 | */ | |
f8f22e53 TH |
2972 | ret = cgroup_update_dfl_csses(cgrp); |
2973 | if (ret) | |
2974 | goto err_undo_css; | |
2975 | ||
f63070d3 TH |
2976 | /* |
2977 | * All tasks are migrated out of disabled csses. Kill or hide | |
2978 | * them. A css is hidden when the userland requests it to be | |
b4536f0c TH |
2979 | * disabled while other subsystems are still depending on it. The |
2980 | * css must not actively control resources and be in the vanilla | |
2981 | * state if it's made visible again later. Controllers which may | |
2982 | * be depended upon should provide ->css_reset() for this purpose. | |
f63070d3 | 2983 | */ |
f8f22e53 TH |
2984 | for_each_subsys(ss, ssid) { |
2985 | if (!(disable & (1 << ssid))) | |
2986 | continue; | |
2987 | ||
f63070d3 | 2988 | cgroup_for_each_live_child(child, cgrp) { |
b4536f0c TH |
2989 | struct cgroup_subsys_state *css = cgroup_css(child, ss); |
2990 | ||
2991 | if (css_disable & (1 << ssid)) { | |
2992 | kill_css(css); | |
2993 | } else { | |
f63070d3 | 2994 | cgroup_clear_dir(child, 1 << ssid); |
b4536f0c TH |
2995 | if (ss->css_reset) |
2996 | ss->css_reset(css); | |
2997 | } | |
f63070d3 | 2998 | } |
f8f22e53 TH |
2999 | } |
3000 | ||
56c807ba TH |
3001 | /* |
3002 | * The effective csses of all the descendants (excluding @cgrp) may | |
3003 | * have changed. Subsystems can optionally subscribe to this event | |
3004 | * by implementing ->css_e_css_changed() which is invoked if any of | |
3005 | * the effective csses seen from the css's cgroup may have changed. | |
3006 | */ | |
3007 | for_each_subsys(ss, ssid) { | |
3008 | struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss); | |
3009 | struct cgroup_subsys_state *css; | |
3010 | ||
3011 | if (!ss->css_e_css_changed || !this_css) | |
3012 | continue; | |
3013 | ||
3014 | css_for_each_descendant_pre(css, this_css) | |
3015 | if (css != this_css) | |
3016 | ss->css_e_css_changed(css); | |
3017 | } | |
3018 | ||
f8f22e53 TH |
3019 | kernfs_activate(cgrp->kn); |
3020 | ret = 0; | |
3021 | out_unlock: | |
a9746d8d | 3022 | cgroup_kn_unlock(of->kn); |
451af504 | 3023 | return ret ?: nbytes; |
f8f22e53 TH |
3024 | |
3025 | err_undo_css: | |
755bf5ee TH |
3026 | cgrp->subtree_control = old_sc; |
3027 | cgrp->child_subsys_mask = old_ss; | |
f8f22e53 TH |
3028 | |
3029 | for_each_subsys(ss, ssid) { | |
3030 | if (!(enable & (1 << ssid))) | |
3031 | continue; | |
3032 | ||
3033 | cgroup_for_each_live_child(child, cgrp) { | |
3034 | struct cgroup_subsys_state *css = cgroup_css(child, ss); | |
f63070d3 TH |
3035 | |
3036 | if (!css) | |
3037 | continue; | |
3038 | ||
3039 | if (css_enable & (1 << ssid)) | |
f8f22e53 | 3040 | kill_css(css); |
f63070d3 TH |
3041 | else |
3042 | cgroup_clear_dir(child, 1 << ssid); | |
f8f22e53 TH |
3043 | } |
3044 | } | |
3045 | goto out_unlock; | |
3046 | } | |
3047 | ||
4a07c222 | 3048 | static int cgroup_events_show(struct seq_file *seq, void *v) |
842b597e | 3049 | { |
4a07c222 TH |
3050 | seq_printf(seq, "populated %d\n", |
3051 | (bool)seq_css(seq)->cgroup->populated_cnt); | |
842b597e TH |
3052 | return 0; |
3053 | } | |
3054 | ||
2bd59d48 TH |
3055 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
3056 | size_t nbytes, loff_t off) | |
355e0c48 | 3057 | { |
2bd59d48 TH |
3058 | struct cgroup *cgrp = of->kn->parent->priv; |
3059 | struct cftype *cft = of->kn->priv; | |
3060 | struct cgroup_subsys_state *css; | |
a742c59d | 3061 | int ret; |
355e0c48 | 3062 | |
b4168640 TH |
3063 | if (cft->write) |
3064 | return cft->write(of, buf, nbytes, off); | |
3065 | ||
2bd59d48 TH |
3066 | /* |
3067 | * kernfs guarantees that a file isn't deleted with operations in | |
3068 | * flight, which means that the matching css is and stays alive and | |
3069 | * doesn't need to be pinned. The RCU locking is not necessary | |
3070 | * either. It's just for the convenience of using cgroup_css(). | |
3071 | */ | |
3072 | rcu_read_lock(); | |
3073 | css = cgroup_css(cgrp, cft->ss); | |
3074 | rcu_read_unlock(); | |
a742c59d | 3075 | |
451af504 | 3076 | if (cft->write_u64) { |
a742c59d TH |
3077 | unsigned long long v; |
3078 | ret = kstrtoull(buf, 0, &v); | |
3079 | if (!ret) | |
3080 | ret = cft->write_u64(css, cft, v); | |
3081 | } else if (cft->write_s64) { | |
3082 | long long v; | |
3083 | ret = kstrtoll(buf, 0, &v); | |
3084 | if (!ret) | |
3085 | ret = cft->write_s64(css, cft, v); | |
e73d2c61 | 3086 | } else { |
a742c59d | 3087 | ret = -EINVAL; |
e73d2c61 | 3088 | } |
2bd59d48 | 3089 | |
a742c59d | 3090 | return ret ?: nbytes; |
355e0c48 PM |
3091 | } |
3092 | ||
6612f05b | 3093 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 3094 | { |
2bd59d48 | 3095 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
3096 | } |
3097 | ||
6612f05b | 3098 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 3099 | { |
2bd59d48 | 3100 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
3101 | } |
3102 | ||
6612f05b | 3103 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 3104 | { |
2bd59d48 | 3105 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
3106 | } |
3107 | ||
91796569 | 3108 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 3109 | { |
7da11279 TH |
3110 | struct cftype *cft = seq_cft(m); |
3111 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 3112 | |
2da8ca82 TH |
3113 | if (cft->seq_show) |
3114 | return cft->seq_show(m, arg); | |
e73d2c61 | 3115 | |
f4c753b7 | 3116 | if (cft->read_u64) |
896f5199 TH |
3117 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
3118 | else if (cft->read_s64) | |
3119 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
3120 | else | |
3121 | return -EINVAL; | |
3122 | return 0; | |
91796569 PM |
3123 | } |
3124 | ||
2bd59d48 TH |
3125 | static struct kernfs_ops cgroup_kf_single_ops = { |
3126 | .atomic_write_len = PAGE_SIZE, | |
3127 | .write = cgroup_file_write, | |
3128 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
3129 | }; |
3130 | ||
2bd59d48 TH |
3131 | static struct kernfs_ops cgroup_kf_ops = { |
3132 | .atomic_write_len = PAGE_SIZE, | |
3133 | .write = cgroup_file_write, | |
3134 | .seq_start = cgroup_seqfile_start, | |
3135 | .seq_next = cgroup_seqfile_next, | |
3136 | .seq_stop = cgroup_seqfile_stop, | |
3137 | .seq_show = cgroup_seqfile_show, | |
3138 | }; | |
ddbcc7e8 PM |
3139 | |
3140 | /* | |
3141 | * cgroup_rename - Only allow simple rename of directories in place. | |
3142 | */ | |
2bd59d48 TH |
3143 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
3144 | const char *new_name_str) | |
ddbcc7e8 | 3145 | { |
2bd59d48 | 3146 | struct cgroup *cgrp = kn->priv; |
65dff759 | 3147 | int ret; |
65dff759 | 3148 | |
2bd59d48 | 3149 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 3150 | return -ENOTDIR; |
2bd59d48 | 3151 | if (kn->parent != new_parent) |
ddbcc7e8 | 3152 | return -EIO; |
65dff759 | 3153 | |
6db8e85c TH |
3154 | /* |
3155 | * This isn't a proper migration and its usefulness is very | |
aa6ec29b | 3156 | * limited. Disallow on the default hierarchy. |
6db8e85c | 3157 | */ |
aa6ec29b | 3158 | if (cgroup_on_dfl(cgrp)) |
6db8e85c | 3159 | return -EPERM; |
099fca32 | 3160 | |
e1b2dc17 | 3161 | /* |
8353da1f | 3162 | * We're gonna grab cgroup_mutex which nests outside kernfs |
e1b2dc17 | 3163 | * active_ref. kernfs_rename() doesn't require active_ref |
8353da1f | 3164 | * protection. Break them before grabbing cgroup_mutex. |
e1b2dc17 TH |
3165 | */ |
3166 | kernfs_break_active_protection(new_parent); | |
3167 | kernfs_break_active_protection(kn); | |
099fca32 | 3168 | |
2bd59d48 | 3169 | mutex_lock(&cgroup_mutex); |
099fca32 | 3170 | |
2bd59d48 | 3171 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 3172 | |
2bd59d48 | 3173 | mutex_unlock(&cgroup_mutex); |
e1b2dc17 TH |
3174 | |
3175 | kernfs_unbreak_active_protection(kn); | |
3176 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 3177 | return ret; |
099fca32 LZ |
3178 | } |
3179 | ||
49957f8e TH |
3180 | /* set uid and gid of cgroup dirs and files to that of the creator */ |
3181 | static int cgroup_kn_set_ugid(struct kernfs_node *kn) | |
3182 | { | |
3183 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, | |
3184 | .ia_uid = current_fsuid(), | |
3185 | .ia_gid = current_fsgid(), }; | |
3186 | ||
3187 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && | |
3188 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) | |
3189 | return 0; | |
3190 | ||
3191 | return kernfs_setattr(kn, &iattr); | |
3192 | } | |
3193 | ||
2bb566cb | 3194 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) |
ddbcc7e8 | 3195 | { |
8d7e6fb0 | 3196 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
3197 | struct kernfs_node *kn; |
3198 | struct lock_class_key *key = NULL; | |
49957f8e | 3199 | int ret; |
05ef1d7c | 3200 | |
2bd59d48 TH |
3201 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
3202 | key = &cft->lockdep_key; | |
3203 | #endif | |
3204 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
3205 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
dfeb0750 | 3206 | NULL, key); |
49957f8e TH |
3207 | if (IS_ERR(kn)) |
3208 | return PTR_ERR(kn); | |
3209 | ||
3210 | ret = cgroup_kn_set_ugid(kn); | |
f8f22e53 | 3211 | if (ret) { |
49957f8e | 3212 | kernfs_remove(kn); |
f8f22e53 TH |
3213 | return ret; |
3214 | } | |
3215 | ||
187fe840 TH |
3216 | if (cft->write == cgroup_procs_write) |
3217 | cgrp->procs_kn = kn; | |
4a07c222 TH |
3218 | else if (cft->seq_show == cgroup_events_show) |
3219 | cgrp->events_kn = kn; | |
f8f22e53 | 3220 | return 0; |
ddbcc7e8 PM |
3221 | } |
3222 | ||
b1f28d31 TH |
3223 | /** |
3224 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
3225 | * @cgrp: the target cgroup | |
b1f28d31 TH |
3226 | * @cfts: array of cftypes to be added |
3227 | * @is_add: whether to add or remove | |
3228 | * | |
3229 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
2bb566cb TH |
3230 | * For removals, this function never fails. If addition fails, this |
3231 | * function doesn't remove files already added. The caller is responsible | |
3232 | * for cleaning up. | |
b1f28d31 | 3233 | */ |
2bb566cb TH |
3234 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
3235 | bool is_add) | |
ddbcc7e8 | 3236 | { |
03b1cde6 | 3237 | struct cftype *cft; |
b1f28d31 TH |
3238 | int ret; |
3239 | ||
01f6474c | 3240 | lockdep_assert_held(&cgroup_mutex); |
db0416b6 TH |
3241 | |
3242 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 3243 | /* does cft->flags tell us to skip this file on @cgrp? */ |
05ebb6e6 | 3244 | if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
8cbbf2c9 | 3245 | continue; |
05ebb6e6 | 3246 | if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
873fe09e | 3247 | continue; |
d51f39b0 | 3248 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
f33fddc2 | 3249 | continue; |
d51f39b0 | 3250 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
f33fddc2 G |
3251 | continue; |
3252 | ||
2739d3cc | 3253 | if (is_add) { |
2bb566cb | 3254 | ret = cgroup_add_file(cgrp, cft); |
b1f28d31 | 3255 | if (ret) { |
ed3d261b JP |
3256 | pr_warn("%s: failed to add %s, err=%d\n", |
3257 | __func__, cft->name, ret); | |
b1f28d31 TH |
3258 | return ret; |
3259 | } | |
2739d3cc LZ |
3260 | } else { |
3261 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 3262 | } |
ddbcc7e8 | 3263 | } |
b1f28d31 | 3264 | return 0; |
ddbcc7e8 PM |
3265 | } |
3266 | ||
21a2d343 | 3267 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
3268 | { |
3269 | LIST_HEAD(pending); | |
2bb566cb | 3270 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 3271 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 3272 | struct cgroup_subsys_state *css; |
9ccece80 | 3273 | int ret = 0; |
8e3f6541 | 3274 | |
01f6474c | 3275 | lockdep_assert_held(&cgroup_mutex); |
e8c82d20 | 3276 | |
e8c82d20 | 3277 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 3278 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
3279 | struct cgroup *cgrp = css->cgroup; |
3280 | ||
e8c82d20 LZ |
3281 | if (cgroup_is_dead(cgrp)) |
3282 | continue; | |
3283 | ||
21a2d343 | 3284 | ret = cgroup_addrm_files(cgrp, cfts, is_add); |
9ccece80 TH |
3285 | if (ret) |
3286 | break; | |
8e3f6541 | 3287 | } |
21a2d343 TH |
3288 | |
3289 | if (is_add && !ret) | |
3290 | kernfs_activate(root->kn); | |
9ccece80 | 3291 | return ret; |
8e3f6541 TH |
3292 | } |
3293 | ||
2da440a2 | 3294 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 3295 | { |
2bb566cb | 3296 | struct cftype *cft; |
8e3f6541 | 3297 | |
2bd59d48 TH |
3298 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3299 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
3300 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
3301 | kfree(cft->kf_ops); | |
3302 | cft->kf_ops = NULL; | |
2da440a2 | 3303 | cft->ss = NULL; |
a8ddc821 TH |
3304 | |
3305 | /* revert flags set by cgroup core while adding @cfts */ | |
05ebb6e6 | 3306 | cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
2bd59d48 | 3307 | } |
2da440a2 TH |
3308 | } |
3309 | ||
2bd59d48 | 3310 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
3311 | { |
3312 | struct cftype *cft; | |
3313 | ||
2bd59d48 TH |
3314 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3315 | struct kernfs_ops *kf_ops; | |
3316 | ||
0adb0704 TH |
3317 | WARN_ON(cft->ss || cft->kf_ops); |
3318 | ||
2bd59d48 TH |
3319 | if (cft->seq_start) |
3320 | kf_ops = &cgroup_kf_ops; | |
3321 | else | |
3322 | kf_ops = &cgroup_kf_single_ops; | |
3323 | ||
3324 | /* | |
3325 | * Ugh... if @cft wants a custom max_write_len, we need to | |
3326 | * make a copy of kf_ops to set its atomic_write_len. | |
3327 | */ | |
3328 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
3329 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
3330 | if (!kf_ops) { | |
3331 | cgroup_exit_cftypes(cfts); | |
3332 | return -ENOMEM; | |
3333 | } | |
3334 | kf_ops->atomic_write_len = cft->max_write_len; | |
3335 | } | |
8e3f6541 | 3336 | |
2bd59d48 | 3337 | cft->kf_ops = kf_ops; |
2bb566cb | 3338 | cft->ss = ss; |
2bd59d48 | 3339 | } |
2bb566cb | 3340 | |
2bd59d48 | 3341 | return 0; |
2da440a2 TH |
3342 | } |
3343 | ||
21a2d343 TH |
3344 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
3345 | { | |
01f6474c | 3346 | lockdep_assert_held(&cgroup_mutex); |
21a2d343 TH |
3347 | |
3348 | if (!cfts || !cfts[0].ss) | |
3349 | return -ENOENT; | |
3350 | ||
3351 | list_del(&cfts->node); | |
3352 | cgroup_apply_cftypes(cfts, false); | |
3353 | cgroup_exit_cftypes(cfts); | |
3354 | return 0; | |
8e3f6541 | 3355 | } |
8e3f6541 | 3356 | |
79578621 TH |
3357 | /** |
3358 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
3359 | * @cfts: zero-length name terminated array of cftypes |
3360 | * | |
2bb566cb TH |
3361 | * Unregister @cfts. Files described by @cfts are removed from all |
3362 | * existing cgroups and all future cgroups won't have them either. This | |
3363 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
3364 | * |
3365 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 3366 | * registered. |
79578621 | 3367 | */ |
2bb566cb | 3368 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 3369 | { |
21a2d343 | 3370 | int ret; |
79578621 | 3371 | |
01f6474c | 3372 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3373 | ret = cgroup_rm_cftypes_locked(cfts); |
01f6474c | 3374 | mutex_unlock(&cgroup_mutex); |
21a2d343 | 3375 | return ret; |
80b13586 TH |
3376 | } |
3377 | ||
8e3f6541 TH |
3378 | /** |
3379 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
3380 | * @ss: target cgroup subsystem | |
3381 | * @cfts: zero-length name terminated array of cftypes | |
3382 | * | |
3383 | * Register @cfts to @ss. Files described by @cfts are created for all | |
3384 | * existing cgroups to which @ss is attached and all future cgroups will | |
3385 | * have them too. This function can be called anytime whether @ss is | |
3386 | * attached or not. | |
3387 | * | |
3388 | * Returns 0 on successful registration, -errno on failure. Note that this | |
3389 | * function currently returns 0 as long as @cfts registration is successful | |
3390 | * even if some file creation attempts on existing cgroups fail. | |
3391 | */ | |
2cf669a5 | 3392 | static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 3393 | { |
9ccece80 | 3394 | int ret; |
8e3f6541 | 3395 | |
fc5ed1e9 | 3396 | if (!cgroup_ssid_enabled(ss->id)) |
c731ae1d LZ |
3397 | return 0; |
3398 | ||
dc5736ed LZ |
3399 | if (!cfts || cfts[0].name[0] == '\0') |
3400 | return 0; | |
2bb566cb | 3401 | |
2bd59d48 TH |
3402 | ret = cgroup_init_cftypes(ss, cfts); |
3403 | if (ret) | |
3404 | return ret; | |
79578621 | 3405 | |
01f6474c | 3406 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3407 | |
0adb0704 | 3408 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 3409 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 3410 | if (ret) |
21a2d343 | 3411 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 3412 | |
01f6474c | 3413 | mutex_unlock(&cgroup_mutex); |
9ccece80 | 3414 | return ret; |
79578621 TH |
3415 | } |
3416 | ||
a8ddc821 TH |
3417 | /** |
3418 | * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy | |
3419 | * @ss: target cgroup subsystem | |
3420 | * @cfts: zero-length name terminated array of cftypes | |
3421 | * | |
3422 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3423 | * the default hierarchy. | |
3424 | */ | |
3425 | int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
3426 | { | |
3427 | struct cftype *cft; | |
3428 | ||
3429 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
05ebb6e6 | 3430 | cft->flags |= __CFTYPE_ONLY_ON_DFL; |
a8ddc821 TH |
3431 | return cgroup_add_cftypes(ss, cfts); |
3432 | } | |
3433 | ||
3434 | /** | |
3435 | * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies | |
3436 | * @ss: target cgroup subsystem | |
3437 | * @cfts: zero-length name terminated array of cftypes | |
3438 | * | |
3439 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3440 | * the legacy hierarchies. | |
3441 | */ | |
2cf669a5 TH |
3442 | int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
3443 | { | |
a8ddc821 TH |
3444 | struct cftype *cft; |
3445 | ||
fa8137be VG |
3446 | /* |
3447 | * If legacy_flies_on_dfl, we want to show the legacy files on the | |
3448 | * dfl hierarchy but iff the target subsystem hasn't been updated | |
3449 | * for the dfl hierarchy yet. | |
3450 | */ | |
3451 | if (!cgroup_legacy_files_on_dfl || | |
3452 | ss->dfl_cftypes != ss->legacy_cftypes) { | |
3453 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
3454 | cft->flags |= __CFTYPE_NOT_ON_DFL; | |
3455 | } | |
3456 | ||
2cf669a5 TH |
3457 | return cgroup_add_cftypes(ss, cfts); |
3458 | } | |
3459 | ||
a043e3b2 LZ |
3460 | /** |
3461 | * cgroup_task_count - count the number of tasks in a cgroup. | |
3462 | * @cgrp: the cgroup in question | |
3463 | * | |
3464 | * Return the number of tasks in the cgroup. | |
3465 | */ | |
07bc356e | 3466 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
3467 | { |
3468 | int count = 0; | |
69d0206c | 3469 | struct cgrp_cset_link *link; |
817929ec | 3470 | |
96d365e0 | 3471 | down_read(&css_set_rwsem); |
69d0206c TH |
3472 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
3473 | count += atomic_read(&link->cset->refcount); | |
96d365e0 | 3474 | up_read(&css_set_rwsem); |
bbcb81d0 PM |
3475 | return count; |
3476 | } | |
3477 | ||
53fa5261 | 3478 | /** |
492eb21b | 3479 | * css_next_child - find the next child of a given css |
c2931b70 TH |
3480 | * @pos: the current position (%NULL to initiate traversal) |
3481 | * @parent: css whose children to walk | |
53fa5261 | 3482 | * |
c2931b70 | 3483 | * This function returns the next child of @parent and should be called |
87fb54f1 | 3484 | * under either cgroup_mutex or RCU read lock. The only requirement is |
c2931b70 TH |
3485 | * that @parent and @pos are accessible. The next sibling is guaranteed to |
3486 | * be returned regardless of their states. | |
3487 | * | |
3488 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3489 | * css which finished ->css_online() is guaranteed to be visible in the | |
3490 | * future iterations and will stay visible until the last reference is put. | |
3491 | * A css which hasn't finished ->css_online() or already finished | |
3492 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3493 | * responsibility to synchronize against on/offlining. | |
53fa5261 | 3494 | */ |
c2931b70 TH |
3495 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
3496 | struct cgroup_subsys_state *parent) | |
53fa5261 | 3497 | { |
c2931b70 | 3498 | struct cgroup_subsys_state *next; |
53fa5261 | 3499 | |
8353da1f | 3500 | cgroup_assert_mutex_or_rcu_locked(); |
53fa5261 TH |
3501 | |
3502 | /* | |
de3f0341 TH |
3503 | * @pos could already have been unlinked from the sibling list. |
3504 | * Once a cgroup is removed, its ->sibling.next is no longer | |
3505 | * updated when its next sibling changes. CSS_RELEASED is set when | |
3506 | * @pos is taken off list, at which time its next pointer is valid, | |
3507 | * and, as releases are serialized, the one pointed to by the next | |
3508 | * pointer is guaranteed to not have started release yet. This | |
3509 | * implies that if we observe !CSS_RELEASED on @pos in this RCU | |
3510 | * critical section, the one pointed to by its next pointer is | |
3511 | * guaranteed to not have finished its RCU grace period even if we | |
3512 | * have dropped rcu_read_lock() inbetween iterations. | |
3b287a50 | 3513 | * |
de3f0341 TH |
3514 | * If @pos has CSS_RELEASED set, its next pointer can't be |
3515 | * dereferenced; however, as each css is given a monotonically | |
3516 | * increasing unique serial number and always appended to the | |
3517 | * sibling list, the next one can be found by walking the parent's | |
3518 | * children until the first css with higher serial number than | |
3519 | * @pos's. While this path can be slower, it happens iff iteration | |
3520 | * races against release and the race window is very small. | |
53fa5261 | 3521 | */ |
3b287a50 | 3522 | if (!pos) { |
c2931b70 TH |
3523 | next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
3524 | } else if (likely(!(pos->flags & CSS_RELEASED))) { | |
3525 | next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); | |
3b287a50 | 3526 | } else { |
c2931b70 | 3527 | list_for_each_entry_rcu(next, &parent->children, sibling) |
3b287a50 TH |
3528 | if (next->serial_nr > pos->serial_nr) |
3529 | break; | |
53fa5261 TH |
3530 | } |
3531 | ||
3b281afb TH |
3532 | /* |
3533 | * @next, if not pointing to the head, can be dereferenced and is | |
c2931b70 | 3534 | * the next sibling. |
3b281afb | 3535 | */ |
c2931b70 TH |
3536 | if (&next->sibling != &parent->children) |
3537 | return next; | |
3b281afb | 3538 | return NULL; |
53fa5261 | 3539 | } |
53fa5261 | 3540 | |
574bd9f7 | 3541 | /** |
492eb21b | 3542 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 3543 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3544 | * @root: css whose descendants to walk |
574bd9f7 | 3545 | * |
492eb21b | 3546 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
3547 | * to visit for pre-order traversal of @root's descendants. @root is |
3548 | * included in the iteration and the first node to be visited. | |
75501a6d | 3549 | * |
87fb54f1 TH |
3550 | * While this function requires cgroup_mutex or RCU read locking, it |
3551 | * doesn't require the whole traversal to be contained in a single critical | |
3552 | * section. This function will return the correct next descendant as long | |
3553 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
c2931b70 TH |
3554 | * |
3555 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3556 | * css which finished ->css_online() is guaranteed to be visible in the | |
3557 | * future iterations and will stay visible until the last reference is put. | |
3558 | * A css which hasn't finished ->css_online() or already finished | |
3559 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3560 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3561 | */ |
492eb21b TH |
3562 | struct cgroup_subsys_state * |
3563 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
3564 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3565 | { |
492eb21b | 3566 | struct cgroup_subsys_state *next; |
574bd9f7 | 3567 | |
8353da1f | 3568 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3569 | |
bd8815a6 | 3570 | /* if first iteration, visit @root */ |
7805d000 | 3571 | if (!pos) |
bd8815a6 | 3572 | return root; |
574bd9f7 TH |
3573 | |
3574 | /* visit the first child if exists */ | |
492eb21b | 3575 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
3576 | if (next) |
3577 | return next; | |
3578 | ||
3579 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b | 3580 | while (pos != root) { |
5c9d535b | 3581 | next = css_next_child(pos, pos->parent); |
75501a6d | 3582 | if (next) |
574bd9f7 | 3583 | return next; |
5c9d535b | 3584 | pos = pos->parent; |
7805d000 | 3585 | } |
574bd9f7 TH |
3586 | |
3587 | return NULL; | |
3588 | } | |
574bd9f7 | 3589 | |
12a9d2fe | 3590 | /** |
492eb21b TH |
3591 | * css_rightmost_descendant - return the rightmost descendant of a css |
3592 | * @pos: css of interest | |
12a9d2fe | 3593 | * |
492eb21b TH |
3594 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
3595 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 3596 | * subtree of @pos. |
75501a6d | 3597 | * |
87fb54f1 TH |
3598 | * While this function requires cgroup_mutex or RCU read locking, it |
3599 | * doesn't require the whole traversal to be contained in a single critical | |
3600 | * section. This function will return the correct rightmost descendant as | |
3601 | * long as @pos is accessible. | |
12a9d2fe | 3602 | */ |
492eb21b TH |
3603 | struct cgroup_subsys_state * |
3604 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 3605 | { |
492eb21b | 3606 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 3607 | |
8353da1f | 3608 | cgroup_assert_mutex_or_rcu_locked(); |
12a9d2fe TH |
3609 | |
3610 | do { | |
3611 | last = pos; | |
3612 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3613 | pos = NULL; | |
492eb21b | 3614 | css_for_each_child(tmp, last) |
12a9d2fe TH |
3615 | pos = tmp; |
3616 | } while (pos); | |
3617 | ||
3618 | return last; | |
3619 | } | |
12a9d2fe | 3620 | |
492eb21b TH |
3621 | static struct cgroup_subsys_state * |
3622 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 3623 | { |
492eb21b | 3624 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
3625 | |
3626 | do { | |
3627 | last = pos; | |
492eb21b | 3628 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
3629 | } while (pos); |
3630 | ||
3631 | return last; | |
3632 | } | |
3633 | ||
3634 | /** | |
492eb21b | 3635 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 3636 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3637 | * @root: css whose descendants to walk |
574bd9f7 | 3638 | * |
492eb21b | 3639 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
3640 | * to visit for post-order traversal of @root's descendants. @root is |
3641 | * included in the iteration and the last node to be visited. | |
75501a6d | 3642 | * |
87fb54f1 TH |
3643 | * While this function requires cgroup_mutex or RCU read locking, it |
3644 | * doesn't require the whole traversal to be contained in a single critical | |
3645 | * section. This function will return the correct next descendant as long | |
3646 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
3647 | * @cgroup. | |
c2931b70 TH |
3648 | * |
3649 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3650 | * css which finished ->css_online() is guaranteed to be visible in the | |
3651 | * future iterations and will stay visible until the last reference is put. | |
3652 | * A css which hasn't finished ->css_online() or already finished | |
3653 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3654 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3655 | */ |
492eb21b TH |
3656 | struct cgroup_subsys_state * |
3657 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
3658 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3659 | { |
492eb21b | 3660 | struct cgroup_subsys_state *next; |
574bd9f7 | 3661 | |
8353da1f | 3662 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3663 | |
58b79a91 TH |
3664 | /* if first iteration, visit leftmost descendant which may be @root */ |
3665 | if (!pos) | |
3666 | return css_leftmost_descendant(root); | |
574bd9f7 | 3667 | |
bd8815a6 TH |
3668 | /* if we visited @root, we're done */ |
3669 | if (pos == root) | |
3670 | return NULL; | |
3671 | ||
574bd9f7 | 3672 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
5c9d535b | 3673 | next = css_next_child(pos, pos->parent); |
75501a6d | 3674 | if (next) |
492eb21b | 3675 | return css_leftmost_descendant(next); |
574bd9f7 TH |
3676 | |
3677 | /* no sibling left, visit parent */ | |
5c9d535b | 3678 | return pos->parent; |
574bd9f7 | 3679 | } |
574bd9f7 | 3680 | |
f3d46500 TH |
3681 | /** |
3682 | * css_has_online_children - does a css have online children | |
3683 | * @css: the target css | |
3684 | * | |
3685 | * Returns %true if @css has any online children; otherwise, %false. This | |
3686 | * function can be called from any context but the caller is responsible | |
3687 | * for synchronizing against on/offlining as necessary. | |
3688 | */ | |
3689 | bool css_has_online_children(struct cgroup_subsys_state *css) | |
cbc125ef | 3690 | { |
f3d46500 TH |
3691 | struct cgroup_subsys_state *child; |
3692 | bool ret = false; | |
cbc125ef TH |
3693 | |
3694 | rcu_read_lock(); | |
f3d46500 | 3695 | css_for_each_child(child, css) { |
99bae5f9 | 3696 | if (child->flags & CSS_ONLINE) { |
f3d46500 TH |
3697 | ret = true; |
3698 | break; | |
cbc125ef TH |
3699 | } |
3700 | } | |
3701 | rcu_read_unlock(); | |
f3d46500 | 3702 | return ret; |
574bd9f7 | 3703 | } |
574bd9f7 | 3704 | |
0942eeee | 3705 | /** |
72ec7029 | 3706 | * css_advance_task_iter - advance a task itererator to the next css_set |
0942eeee TH |
3707 | * @it: the iterator to advance |
3708 | * | |
3709 | * Advance @it to the next css_set to walk. | |
d515876e | 3710 | */ |
72ec7029 | 3711 | static void css_advance_task_iter(struct css_task_iter *it) |
d515876e | 3712 | { |
0f0a2b4f | 3713 | struct list_head *l = it->cset_pos; |
d515876e TH |
3714 | struct cgrp_cset_link *link; |
3715 | struct css_set *cset; | |
3716 | ||
3717 | /* Advance to the next non-empty css_set */ | |
3718 | do { | |
3719 | l = l->next; | |
0f0a2b4f TH |
3720 | if (l == it->cset_head) { |
3721 | it->cset_pos = NULL; | |
d515876e TH |
3722 | return; |
3723 | } | |
3ebb2b6e TH |
3724 | |
3725 | if (it->ss) { | |
3726 | cset = container_of(l, struct css_set, | |
3727 | e_cset_node[it->ss->id]); | |
3728 | } else { | |
3729 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
3730 | cset = link->cset; | |
3731 | } | |
c7561128 TH |
3732 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); |
3733 | ||
0f0a2b4f | 3734 | it->cset_pos = l; |
c7561128 TH |
3735 | |
3736 | if (!list_empty(&cset->tasks)) | |
0f0a2b4f | 3737 | it->task_pos = cset->tasks.next; |
c7561128 | 3738 | else |
0f0a2b4f TH |
3739 | it->task_pos = cset->mg_tasks.next; |
3740 | ||
3741 | it->tasks_head = &cset->tasks; | |
3742 | it->mg_tasks_head = &cset->mg_tasks; | |
d515876e TH |
3743 | } |
3744 | ||
0942eeee | 3745 | /** |
72ec7029 TH |
3746 | * css_task_iter_start - initiate task iteration |
3747 | * @css: the css to walk tasks of | |
0942eeee TH |
3748 | * @it: the task iterator to use |
3749 | * | |
72ec7029 TH |
3750 | * Initiate iteration through the tasks of @css. The caller can call |
3751 | * css_task_iter_next() to walk through the tasks until the function | |
3752 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
3753 | * called. | |
0942eeee TH |
3754 | * |
3755 | * Note that this function acquires a lock which is released when the | |
3756 | * iteration finishes. The caller can't sleep while iteration is in | |
3757 | * progress. | |
3758 | */ | |
72ec7029 TH |
3759 | void css_task_iter_start(struct cgroup_subsys_state *css, |
3760 | struct css_task_iter *it) | |
96d365e0 | 3761 | __acquires(css_set_rwsem) |
817929ec | 3762 | { |
56fde9e0 TH |
3763 | /* no one should try to iterate before mounting cgroups */ |
3764 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 3765 | |
96d365e0 | 3766 | down_read(&css_set_rwsem); |
c59cd3d8 | 3767 | |
3ebb2b6e TH |
3768 | it->ss = css->ss; |
3769 | ||
3770 | if (it->ss) | |
3771 | it->cset_pos = &css->cgroup->e_csets[css->ss->id]; | |
3772 | else | |
3773 | it->cset_pos = &css->cgroup->cset_links; | |
3774 | ||
0f0a2b4f | 3775 | it->cset_head = it->cset_pos; |
c59cd3d8 | 3776 | |
72ec7029 | 3777 | css_advance_task_iter(it); |
817929ec PM |
3778 | } |
3779 | ||
0942eeee | 3780 | /** |
72ec7029 | 3781 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
3782 | * @it: the task iterator being iterated |
3783 | * | |
3784 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
3785 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
3786 | * reaches the end. | |
0942eeee | 3787 | */ |
72ec7029 | 3788 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec PM |
3789 | { |
3790 | struct task_struct *res; | |
0f0a2b4f | 3791 | struct list_head *l = it->task_pos; |
817929ec PM |
3792 | |
3793 | /* If the iterator cg is NULL, we have no tasks */ | |
0f0a2b4f | 3794 | if (!it->cset_pos) |
817929ec PM |
3795 | return NULL; |
3796 | res = list_entry(l, struct task_struct, cg_list); | |
c7561128 TH |
3797 | |
3798 | /* | |
3799 | * Advance iterator to find next entry. cset->tasks is consumed | |
3800 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
3801 | * next cset. | |
3802 | */ | |
817929ec | 3803 | l = l->next; |
c7561128 | 3804 | |
0f0a2b4f TH |
3805 | if (l == it->tasks_head) |
3806 | l = it->mg_tasks_head->next; | |
c7561128 | 3807 | |
0f0a2b4f | 3808 | if (l == it->mg_tasks_head) |
72ec7029 | 3809 | css_advance_task_iter(it); |
c7561128 | 3810 | else |
0f0a2b4f | 3811 | it->task_pos = l; |
c7561128 | 3812 | |
817929ec PM |
3813 | return res; |
3814 | } | |
3815 | ||
0942eeee | 3816 | /** |
72ec7029 | 3817 | * css_task_iter_end - finish task iteration |
0942eeee TH |
3818 | * @it: the task iterator to finish |
3819 | * | |
72ec7029 | 3820 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 3821 | */ |
72ec7029 | 3822 | void css_task_iter_end(struct css_task_iter *it) |
96d365e0 | 3823 | __releases(css_set_rwsem) |
31a7df01 | 3824 | { |
96d365e0 | 3825 | up_read(&css_set_rwsem); |
31a7df01 CW |
3826 | } |
3827 | ||
3828 | /** | |
8cc99345 TH |
3829 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
3830 | * @to: cgroup to which the tasks will be moved | |
3831 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 3832 | * |
eaf797ab TH |
3833 | * Locking rules between cgroup_post_fork() and the migration path |
3834 | * guarantee that, if a task is forking while being migrated, the new child | |
3835 | * is guaranteed to be either visible in the source cgroup after the | |
3836 | * parent's migration is complete or put into the target cgroup. No task | |
3837 | * can slip out of migration through forking. | |
31a7df01 | 3838 | */ |
8cc99345 | 3839 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 3840 | { |
952aaa12 TH |
3841 | LIST_HEAD(preloaded_csets); |
3842 | struct cgrp_cset_link *link; | |
72ec7029 | 3843 | struct css_task_iter it; |
e406d1cf | 3844 | struct task_struct *task; |
952aaa12 | 3845 | int ret; |
31a7df01 | 3846 | |
952aaa12 | 3847 | mutex_lock(&cgroup_mutex); |
31a7df01 | 3848 | |
952aaa12 TH |
3849 | /* all tasks in @from are being moved, all csets are source */ |
3850 | down_read(&css_set_rwsem); | |
3851 | list_for_each_entry(link, &from->cset_links, cset_link) | |
3852 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
3853 | up_read(&css_set_rwsem); | |
31a7df01 | 3854 | |
952aaa12 TH |
3855 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
3856 | if (ret) | |
3857 | goto out_err; | |
8cc99345 | 3858 | |
952aaa12 TH |
3859 | /* |
3860 | * Migrate tasks one-by-one until @form is empty. This fails iff | |
3861 | * ->can_attach() fails. | |
3862 | */ | |
e406d1cf | 3863 | do { |
9d800df1 | 3864 | css_task_iter_start(&from->self, &it); |
e406d1cf TH |
3865 | task = css_task_iter_next(&it); |
3866 | if (task) | |
3867 | get_task_struct(task); | |
3868 | css_task_iter_end(&it); | |
3869 | ||
3870 | if (task) { | |
952aaa12 | 3871 | ret = cgroup_migrate(to, task, false); |
e406d1cf TH |
3872 | put_task_struct(task); |
3873 | } | |
3874 | } while (task && !ret); | |
952aaa12 TH |
3875 | out_err: |
3876 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 3877 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 3878 | return ret; |
8cc99345 TH |
3879 | } |
3880 | ||
bbcb81d0 | 3881 | /* |
102a775e | 3882 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3883 | * |
3884 | * Reading this file can return large amounts of data if a cgroup has | |
3885 | * *lots* of attached tasks. So it may need several calls to read(), | |
3886 | * but we cannot guarantee that the information we produce is correct | |
3887 | * unless we produce it entirely atomically. | |
3888 | * | |
bbcb81d0 | 3889 | */ |
bbcb81d0 | 3890 | |
24528255 LZ |
3891 | /* which pidlist file are we talking about? */ |
3892 | enum cgroup_filetype { | |
3893 | CGROUP_FILE_PROCS, | |
3894 | CGROUP_FILE_TASKS, | |
3895 | }; | |
3896 | ||
3897 | /* | |
3898 | * A pidlist is a list of pids that virtually represents the contents of one | |
3899 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3900 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3901 | * to the cgroup. | |
3902 | */ | |
3903 | struct cgroup_pidlist { | |
3904 | /* | |
3905 | * used to find which pidlist is wanted. doesn't change as long as | |
3906 | * this particular list stays in the list. | |
3907 | */ | |
3908 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3909 | /* array of xids */ | |
3910 | pid_t *list; | |
3911 | /* how many elements the above list has */ | |
3912 | int length; | |
24528255 LZ |
3913 | /* each of these stored in a list by its cgroup */ |
3914 | struct list_head links; | |
3915 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3916 | struct cgroup *owner; | |
b1a21367 TH |
3917 | /* for delayed destruction */ |
3918 | struct delayed_work destroy_dwork; | |
24528255 LZ |
3919 | }; |
3920 | ||
d1d9fd33 BB |
3921 | /* |
3922 | * The following two functions "fix" the issue where there are more pids | |
3923 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3924 | * TODO: replace with a kernel-wide solution to this problem | |
3925 | */ | |
3926 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3927 | static void *pidlist_allocate(int count) | |
3928 | { | |
3929 | if (PIDLIST_TOO_LARGE(count)) | |
3930 | return vmalloc(count * sizeof(pid_t)); | |
3931 | else | |
3932 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3933 | } | |
b1a21367 | 3934 | |
d1d9fd33 BB |
3935 | static void pidlist_free(void *p) |
3936 | { | |
58794514 | 3937 | kvfree(p); |
d1d9fd33 | 3938 | } |
d1d9fd33 | 3939 | |
b1a21367 TH |
3940 | /* |
3941 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
3942 | * should be left afterwards. | |
3943 | */ | |
3944 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
3945 | { | |
3946 | struct cgroup_pidlist *l, *tmp_l; | |
3947 | ||
3948 | mutex_lock(&cgrp->pidlist_mutex); | |
3949 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
3950 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
3951 | mutex_unlock(&cgrp->pidlist_mutex); | |
3952 | ||
3953 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
3954 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
3955 | } | |
3956 | ||
3957 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
3958 | { | |
3959 | struct delayed_work *dwork = to_delayed_work(work); | |
3960 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
3961 | destroy_dwork); | |
3962 | struct cgroup_pidlist *tofree = NULL; | |
3963 | ||
3964 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
3965 | |
3966 | /* | |
04502365 TH |
3967 | * Destroy iff we didn't get queued again. The state won't change |
3968 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 3969 | */ |
04502365 | 3970 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
3971 | list_del(&l->links); |
3972 | pidlist_free(l->list); | |
3973 | put_pid_ns(l->key.ns); | |
3974 | tofree = l; | |
3975 | } | |
3976 | ||
b1a21367 TH |
3977 | mutex_unlock(&l->owner->pidlist_mutex); |
3978 | kfree(tofree); | |
3979 | } | |
3980 | ||
bbcb81d0 | 3981 | /* |
102a775e | 3982 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 3983 | * Returns the number of unique elements. |
bbcb81d0 | 3984 | */ |
6ee211ad | 3985 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 3986 | { |
102a775e | 3987 | int src, dest = 1; |
102a775e BB |
3988 | |
3989 | /* | |
3990 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3991 | * edge cases first; no work needs to be done for either | |
3992 | */ | |
3993 | if (length == 0 || length == 1) | |
3994 | return length; | |
3995 | /* src and dest walk down the list; dest counts unique elements */ | |
3996 | for (src = 1; src < length; src++) { | |
3997 | /* find next unique element */ | |
3998 | while (list[src] == list[src-1]) { | |
3999 | src++; | |
4000 | if (src == length) | |
4001 | goto after; | |
4002 | } | |
4003 | /* dest always points to where the next unique element goes */ | |
4004 | list[dest] = list[src]; | |
4005 | dest++; | |
4006 | } | |
4007 | after: | |
102a775e BB |
4008 | return dest; |
4009 | } | |
4010 | ||
afb2bc14 TH |
4011 | /* |
4012 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
4013 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
4014 | * different per namespace, each namespace needs differently sorted list, | |
4015 | * making it impossible to use, for example, single rbtree of member tasks | |
4016 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
4017 | * per open file is dangerous, so cgroup had to implement shared pool of | |
4018 | * pidlists keyed by cgroup and namespace. | |
4019 | * | |
4020 | * All this extra complexity was caused by the original implementation | |
4021 | * committing to an entirely unnecessary property. In the long term, we | |
aa6ec29b TH |
4022 | * want to do away with it. Explicitly scramble sort order if on the |
4023 | * default hierarchy so that no such expectation exists in the new | |
4024 | * interface. | |
afb2bc14 TH |
4025 | * |
4026 | * Scrambling is done by swapping every two consecutive bits, which is | |
4027 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
4028 | */ | |
4029 | static pid_t pid_fry(pid_t pid) | |
4030 | { | |
4031 | unsigned a = pid & 0x55555555; | |
4032 | unsigned b = pid & 0xAAAAAAAA; | |
4033 | ||
4034 | return (a << 1) | (b >> 1); | |
4035 | } | |
4036 | ||
4037 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
4038 | { | |
aa6ec29b | 4039 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4040 | return pid_fry(pid); |
4041 | else | |
4042 | return pid; | |
4043 | } | |
4044 | ||
102a775e BB |
4045 | static int cmppid(const void *a, const void *b) |
4046 | { | |
4047 | return *(pid_t *)a - *(pid_t *)b; | |
4048 | } | |
4049 | ||
afb2bc14 TH |
4050 | static int fried_cmppid(const void *a, const void *b) |
4051 | { | |
4052 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
4053 | } | |
4054 | ||
e6b81710 TH |
4055 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
4056 | enum cgroup_filetype type) | |
4057 | { | |
4058 | struct cgroup_pidlist *l; | |
4059 | /* don't need task_nsproxy() if we're looking at ourself */ | |
4060 | struct pid_namespace *ns = task_active_pid_ns(current); | |
4061 | ||
4062 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
4063 | ||
4064 | list_for_each_entry(l, &cgrp->pidlists, links) | |
4065 | if (l->key.type == type && l->key.ns == ns) | |
4066 | return l; | |
4067 | return NULL; | |
4068 | } | |
4069 | ||
72a8cb30 BB |
4070 | /* |
4071 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
4072 | * returns with the lock on that pidlist already held, and takes care | |
4073 | * of the use count, or returns NULL with no locks held if we're out of | |
4074 | * memory. | |
4075 | */ | |
e6b81710 TH |
4076 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
4077 | enum cgroup_filetype type) | |
72a8cb30 BB |
4078 | { |
4079 | struct cgroup_pidlist *l; | |
b70cc5fd | 4080 | |
e6b81710 TH |
4081 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4082 | ||
4083 | l = cgroup_pidlist_find(cgrp, type); | |
4084 | if (l) | |
4085 | return l; | |
4086 | ||
72a8cb30 | 4087 | /* entry not found; create a new one */ |
f4f4be2b | 4088 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 4089 | if (!l) |
72a8cb30 | 4090 | return l; |
e6b81710 | 4091 | |
b1a21367 | 4092 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 4093 | l->key.type = type; |
e6b81710 TH |
4094 | /* don't need task_nsproxy() if we're looking at ourself */ |
4095 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
4096 | l->owner = cgrp; |
4097 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
4098 | return l; |
4099 | } | |
4100 | ||
102a775e BB |
4101 | /* |
4102 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
4103 | */ | |
72a8cb30 BB |
4104 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
4105 | struct cgroup_pidlist **lp) | |
102a775e BB |
4106 | { |
4107 | pid_t *array; | |
4108 | int length; | |
4109 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 4110 | struct css_task_iter it; |
817929ec | 4111 | struct task_struct *tsk; |
102a775e BB |
4112 | struct cgroup_pidlist *l; |
4113 | ||
4bac00d1 TH |
4114 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4115 | ||
102a775e BB |
4116 | /* |
4117 | * If cgroup gets more users after we read count, we won't have | |
4118 | * enough space - tough. This race is indistinguishable to the | |
4119 | * caller from the case that the additional cgroup users didn't | |
4120 | * show up until sometime later on. | |
4121 | */ | |
4122 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 4123 | array = pidlist_allocate(length); |
102a775e BB |
4124 | if (!array) |
4125 | return -ENOMEM; | |
4126 | /* now, populate the array */ | |
9d800df1 | 4127 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4128 | while ((tsk = css_task_iter_next(&it))) { |
102a775e | 4129 | if (unlikely(n == length)) |
817929ec | 4130 | break; |
102a775e | 4131 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
4132 | if (type == CGROUP_FILE_PROCS) |
4133 | pid = task_tgid_vnr(tsk); | |
4134 | else | |
4135 | pid = task_pid_vnr(tsk); | |
102a775e BB |
4136 | if (pid > 0) /* make sure to only use valid results */ |
4137 | array[n++] = pid; | |
817929ec | 4138 | } |
72ec7029 | 4139 | css_task_iter_end(&it); |
102a775e BB |
4140 | length = n; |
4141 | /* now sort & (if procs) strip out duplicates */ | |
aa6ec29b | 4142 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4143 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
4144 | else | |
4145 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 4146 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 4147 | length = pidlist_uniq(array, length); |
e6b81710 | 4148 | |
e6b81710 | 4149 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 4150 | if (!l) { |
d1d9fd33 | 4151 | pidlist_free(array); |
72a8cb30 | 4152 | return -ENOMEM; |
102a775e | 4153 | } |
e6b81710 TH |
4154 | |
4155 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 4156 | pidlist_free(l->list); |
102a775e BB |
4157 | l->list = array; |
4158 | l->length = length; | |
72a8cb30 | 4159 | *lp = l; |
102a775e | 4160 | return 0; |
bbcb81d0 PM |
4161 | } |
4162 | ||
846c7bb0 | 4163 | /** |
a043e3b2 | 4164 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
4165 | * @stats: cgroupstats to fill information into |
4166 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
4167 | * been requested. | |
a043e3b2 LZ |
4168 | * |
4169 | * Build and fill cgroupstats so that taskstats can export it to user | |
4170 | * space. | |
846c7bb0 BS |
4171 | */ |
4172 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
4173 | { | |
2bd59d48 | 4174 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 4175 | struct cgroup *cgrp; |
72ec7029 | 4176 | struct css_task_iter it; |
846c7bb0 | 4177 | struct task_struct *tsk; |
33d283be | 4178 | |
2bd59d48 TH |
4179 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
4180 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
4181 | kernfs_type(kn) != KERNFS_DIR) | |
4182 | return -EINVAL; | |
4183 | ||
bad34660 LZ |
4184 | mutex_lock(&cgroup_mutex); |
4185 | ||
846c7bb0 | 4186 | /* |
2bd59d48 | 4187 | * We aren't being called from kernfs and there's no guarantee on |
ec903c0c | 4188 | * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
2bd59d48 | 4189 | * @kn->priv is RCU safe. Let's do the RCU dancing. |
846c7bb0 | 4190 | */ |
2bd59d48 TH |
4191 | rcu_read_lock(); |
4192 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 4193 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 4194 | rcu_read_unlock(); |
bad34660 | 4195 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
4196 | return -ENOENT; |
4197 | } | |
bad34660 | 4198 | rcu_read_unlock(); |
846c7bb0 | 4199 | |
9d800df1 | 4200 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4201 | while ((tsk = css_task_iter_next(&it))) { |
846c7bb0 BS |
4202 | switch (tsk->state) { |
4203 | case TASK_RUNNING: | |
4204 | stats->nr_running++; | |
4205 | break; | |
4206 | case TASK_INTERRUPTIBLE: | |
4207 | stats->nr_sleeping++; | |
4208 | break; | |
4209 | case TASK_UNINTERRUPTIBLE: | |
4210 | stats->nr_uninterruptible++; | |
4211 | break; | |
4212 | case TASK_STOPPED: | |
4213 | stats->nr_stopped++; | |
4214 | break; | |
4215 | default: | |
4216 | if (delayacct_is_task_waiting_on_io(tsk)) | |
4217 | stats->nr_io_wait++; | |
4218 | break; | |
4219 | } | |
4220 | } | |
72ec7029 | 4221 | css_task_iter_end(&it); |
846c7bb0 | 4222 | |
bad34660 | 4223 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 4224 | return 0; |
846c7bb0 BS |
4225 | } |
4226 | ||
8f3ff208 | 4227 | |
bbcb81d0 | 4228 | /* |
102a775e | 4229 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 4230 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 4231 | * in the cgroup->l->list array. |
bbcb81d0 | 4232 | */ |
cc31edce | 4233 | |
102a775e | 4234 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 4235 | { |
cc31edce PM |
4236 | /* |
4237 | * Initially we receive a position value that corresponds to | |
4238 | * one more than the last pid shown (or 0 on the first call or | |
4239 | * after a seek to the start). Use a binary-search to find the | |
4240 | * next pid to display, if any | |
4241 | */ | |
2bd59d48 | 4242 | struct kernfs_open_file *of = s->private; |
7da11279 | 4243 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 4244 | struct cgroup_pidlist *l; |
7da11279 | 4245 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 4246 | int index = 0, pid = *pos; |
4bac00d1 TH |
4247 | int *iter, ret; |
4248 | ||
4249 | mutex_lock(&cgrp->pidlist_mutex); | |
4250 | ||
4251 | /* | |
5d22444f | 4252 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 4253 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 4254 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
4255 | * could already have been destroyed. |
4256 | */ | |
5d22444f TH |
4257 | if (of->priv) |
4258 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
4259 | |
4260 | /* | |
4261 | * Either this is the first start() after open or the matching | |
4262 | * pidlist has been destroyed inbetween. Create a new one. | |
4263 | */ | |
5d22444f TH |
4264 | if (!of->priv) { |
4265 | ret = pidlist_array_load(cgrp, type, | |
4266 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
4267 | if (ret) |
4268 | return ERR_PTR(ret); | |
4269 | } | |
5d22444f | 4270 | l = of->priv; |
cc31edce | 4271 | |
cc31edce | 4272 | if (pid) { |
102a775e | 4273 | int end = l->length; |
20777766 | 4274 | |
cc31edce PM |
4275 | while (index < end) { |
4276 | int mid = (index + end) / 2; | |
afb2bc14 | 4277 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
4278 | index = mid; |
4279 | break; | |
afb2bc14 | 4280 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
4281 | index = mid + 1; |
4282 | else | |
4283 | end = mid; | |
4284 | } | |
4285 | } | |
4286 | /* If we're off the end of the array, we're done */ | |
102a775e | 4287 | if (index >= l->length) |
cc31edce PM |
4288 | return NULL; |
4289 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 4290 | iter = l->list + index; |
afb2bc14 | 4291 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
4292 | return iter; |
4293 | } | |
4294 | ||
102a775e | 4295 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 4296 | { |
2bd59d48 | 4297 | struct kernfs_open_file *of = s->private; |
5d22444f | 4298 | struct cgroup_pidlist *l = of->priv; |
62236858 | 4299 | |
5d22444f TH |
4300 | if (l) |
4301 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 4302 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 4303 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
4304 | } |
4305 | ||
102a775e | 4306 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 4307 | { |
2bd59d48 | 4308 | struct kernfs_open_file *of = s->private; |
5d22444f | 4309 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
4310 | pid_t *p = v; |
4311 | pid_t *end = l->list + l->length; | |
cc31edce PM |
4312 | /* |
4313 | * Advance to the next pid in the array. If this goes off the | |
4314 | * end, we're done | |
4315 | */ | |
4316 | p++; | |
4317 | if (p >= end) { | |
4318 | return NULL; | |
4319 | } else { | |
7da11279 | 4320 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
4321 | return p; |
4322 | } | |
4323 | } | |
4324 | ||
102a775e | 4325 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce | 4326 | { |
94ff212d JP |
4327 | seq_printf(s, "%d\n", *(int *)v); |
4328 | ||
4329 | return 0; | |
cc31edce | 4330 | } |
bbcb81d0 | 4331 | |
182446d0 TH |
4332 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
4333 | struct cftype *cft) | |
81a6a5cd | 4334 | { |
182446d0 | 4335 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
4336 | } |
4337 | ||
182446d0 TH |
4338 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
4339 | struct cftype *cft, u64 val) | |
6379c106 | 4340 | { |
6379c106 | 4341 | if (val) |
182446d0 | 4342 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 4343 | else |
182446d0 | 4344 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
4345 | return 0; |
4346 | } | |
4347 | ||
182446d0 TH |
4348 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
4349 | struct cftype *cft) | |
97978e6d | 4350 | { |
182446d0 | 4351 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4352 | } |
4353 | ||
182446d0 TH |
4354 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
4355 | struct cftype *cft, u64 val) | |
97978e6d DL |
4356 | { |
4357 | if (val) | |
182446d0 | 4358 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 4359 | else |
182446d0 | 4360 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4361 | return 0; |
4362 | } | |
4363 | ||
a14c6874 TH |
4364 | /* cgroup core interface files for the default hierarchy */ |
4365 | static struct cftype cgroup_dfl_base_files[] = { | |
81a6a5cd | 4366 | { |
d5c56ced | 4367 | .name = "cgroup.procs", |
6612f05b TH |
4368 | .seq_start = cgroup_pidlist_start, |
4369 | .seq_next = cgroup_pidlist_next, | |
4370 | .seq_stop = cgroup_pidlist_stop, | |
4371 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4372 | .private = CGROUP_FILE_PROCS, |
acbef755 | 4373 | .write = cgroup_procs_write, |
74a1166d | 4374 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 4375 | }, |
f8f22e53 TH |
4376 | { |
4377 | .name = "cgroup.controllers", | |
a14c6874 | 4378 | .flags = CFTYPE_ONLY_ON_ROOT, |
f8f22e53 TH |
4379 | .seq_show = cgroup_root_controllers_show, |
4380 | }, | |
4381 | { | |
4382 | .name = "cgroup.controllers", | |
a14c6874 | 4383 | .flags = CFTYPE_NOT_ON_ROOT, |
f8f22e53 TH |
4384 | .seq_show = cgroup_controllers_show, |
4385 | }, | |
4386 | { | |
4387 | .name = "cgroup.subtree_control", | |
f8f22e53 | 4388 | .seq_show = cgroup_subtree_control_show, |
451af504 | 4389 | .write = cgroup_subtree_control_write, |
f8f22e53 | 4390 | }, |
842b597e | 4391 | { |
4a07c222 | 4392 | .name = "cgroup.events", |
a14c6874 | 4393 | .flags = CFTYPE_NOT_ON_ROOT, |
4a07c222 | 4394 | .seq_show = cgroup_events_show, |
842b597e | 4395 | }, |
a14c6874 TH |
4396 | { } /* terminate */ |
4397 | }; | |
d5c56ced | 4398 | |
a14c6874 TH |
4399 | /* cgroup core interface files for the legacy hierarchies */ |
4400 | static struct cftype cgroup_legacy_base_files[] = { | |
4401 | { | |
4402 | .name = "cgroup.procs", | |
4403 | .seq_start = cgroup_pidlist_start, | |
4404 | .seq_next = cgroup_pidlist_next, | |
4405 | .seq_stop = cgroup_pidlist_stop, | |
4406 | .seq_show = cgroup_pidlist_show, | |
4407 | .private = CGROUP_FILE_PROCS, | |
4408 | .write = cgroup_procs_write, | |
4409 | .mode = S_IRUGO | S_IWUSR, | |
4410 | }, | |
4411 | { | |
4412 | .name = "cgroup.clone_children", | |
4413 | .read_u64 = cgroup_clone_children_read, | |
4414 | .write_u64 = cgroup_clone_children_write, | |
4415 | }, | |
4416 | { | |
4417 | .name = "cgroup.sane_behavior", | |
4418 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4419 | .seq_show = cgroup_sane_behavior_show, | |
4420 | }, | |
d5c56ced TH |
4421 | { |
4422 | .name = "tasks", | |
6612f05b TH |
4423 | .seq_start = cgroup_pidlist_start, |
4424 | .seq_next = cgroup_pidlist_next, | |
4425 | .seq_stop = cgroup_pidlist_stop, | |
4426 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4427 | .private = CGROUP_FILE_TASKS, |
acbef755 | 4428 | .write = cgroup_tasks_write, |
d5c56ced TH |
4429 | .mode = S_IRUGO | S_IWUSR, |
4430 | }, | |
4431 | { | |
4432 | .name = "notify_on_release", | |
d5c56ced TH |
4433 | .read_u64 = cgroup_read_notify_on_release, |
4434 | .write_u64 = cgroup_write_notify_on_release, | |
4435 | }, | |
6e6ff25b TH |
4436 | { |
4437 | .name = "release_agent", | |
a14c6874 | 4438 | .flags = CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 4439 | .seq_show = cgroup_release_agent_show, |
451af504 | 4440 | .write = cgroup_release_agent_write, |
5f469907 | 4441 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 4442 | }, |
db0416b6 | 4443 | { } /* terminate */ |
bbcb81d0 PM |
4444 | }; |
4445 | ||
13af07df | 4446 | /** |
628f7cd4 | 4447 | * cgroup_populate_dir - create subsys files in a cgroup directory |
13af07df | 4448 | * @cgrp: target cgroup |
13af07df | 4449 | * @subsys_mask: mask of the subsystem ids whose files should be added |
bee55099 TH |
4450 | * |
4451 | * On failure, no file is added. | |
13af07df | 4452 | */ |
8ab456ac | 4453 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
ddbcc7e8 | 4454 | { |
ddbcc7e8 | 4455 | struct cgroup_subsys *ss; |
b420ba7d | 4456 | int i, ret = 0; |
bbcb81d0 | 4457 | |
8e3f6541 | 4458 | /* process cftsets of each subsystem */ |
b420ba7d | 4459 | for_each_subsys(ss, i) { |
0adb0704 | 4460 | struct cftype *cfts; |
b420ba7d | 4461 | |
69dfa00c | 4462 | if (!(subsys_mask & (1 << i))) |
13af07df | 4463 | continue; |
8e3f6541 | 4464 | |
0adb0704 TH |
4465 | list_for_each_entry(cfts, &ss->cfts, node) { |
4466 | ret = cgroup_addrm_files(cgrp, cfts, true); | |
bee55099 TH |
4467 | if (ret < 0) |
4468 | goto err; | |
4469 | } | |
ddbcc7e8 | 4470 | } |
ddbcc7e8 | 4471 | return 0; |
bee55099 TH |
4472 | err: |
4473 | cgroup_clear_dir(cgrp, subsys_mask); | |
4474 | return ret; | |
ddbcc7e8 PM |
4475 | } |
4476 | ||
0c21ead1 TH |
4477 | /* |
4478 | * css destruction is four-stage process. | |
4479 | * | |
4480 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
4481 | * Implemented in kill_css(). | |
4482 | * | |
4483 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
ec903c0c TH |
4484 | * and thus css_tryget_online() is guaranteed to fail, the css can be |
4485 | * offlined by invoking offline_css(). After offlining, the base ref is | |
4486 | * put. Implemented in css_killed_work_fn(). | |
0c21ead1 TH |
4487 | * |
4488 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
4489 | * accessors are inside RCU read sections. css_release() schedules the | |
4490 | * RCU callback. | |
4491 | * | |
4492 | * 4. After the grace period, the css can be freed. Implemented in | |
4493 | * css_free_work_fn(). | |
4494 | * | |
4495 | * It is actually hairier because both step 2 and 4 require process context | |
4496 | * and thus involve punting to css->destroy_work adding two additional | |
4497 | * steps to the already complex sequence. | |
4498 | */ | |
35ef10da | 4499 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
4500 | { |
4501 | struct cgroup_subsys_state *css = | |
35ef10da | 4502 | container_of(work, struct cgroup_subsys_state, destroy_work); |
01e58659 | 4503 | struct cgroup_subsys *ss = css->ss; |
0c21ead1 | 4504 | struct cgroup *cgrp = css->cgroup; |
48ddbe19 | 4505 | |
9a1049da TH |
4506 | percpu_ref_exit(&css->refcnt); |
4507 | ||
01e58659 | 4508 | if (ss) { |
9d755d33 | 4509 | /* css free path */ |
01e58659 VD |
4510 | int id = css->id; |
4511 | ||
9d755d33 TH |
4512 | if (css->parent) |
4513 | css_put(css->parent); | |
0ae78e0b | 4514 | |
01e58659 VD |
4515 | ss->css_free(css); |
4516 | cgroup_idr_remove(&ss->css_idr, id); | |
9d755d33 TH |
4517 | cgroup_put(cgrp); |
4518 | } else { | |
4519 | /* cgroup free path */ | |
4520 | atomic_dec(&cgrp->root->nr_cgrps); | |
4521 | cgroup_pidlist_destroy_all(cgrp); | |
971ff493 | 4522 | cancel_work_sync(&cgrp->release_agent_work); |
9d755d33 | 4523 | |
d51f39b0 | 4524 | if (cgroup_parent(cgrp)) { |
9d755d33 TH |
4525 | /* |
4526 | * We get a ref to the parent, and put the ref when | |
4527 | * this cgroup is being freed, so it's guaranteed | |
4528 | * that the parent won't be destroyed before its | |
4529 | * children. | |
4530 | */ | |
d51f39b0 | 4531 | cgroup_put(cgroup_parent(cgrp)); |
9d755d33 TH |
4532 | kernfs_put(cgrp->kn); |
4533 | kfree(cgrp); | |
4534 | } else { | |
4535 | /* | |
4536 | * This is root cgroup's refcnt reaching zero, | |
4537 | * which indicates that the root should be | |
4538 | * released. | |
4539 | */ | |
4540 | cgroup_destroy_root(cgrp->root); | |
4541 | } | |
4542 | } | |
48ddbe19 TH |
4543 | } |
4544 | ||
0c21ead1 | 4545 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
4546 | { |
4547 | struct cgroup_subsys_state *css = | |
0c21ead1 | 4548 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 4549 | |
35ef10da | 4550 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 4551 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
4552 | } |
4553 | ||
25e15d83 | 4554 | static void css_release_work_fn(struct work_struct *work) |
d3daf28d TH |
4555 | { |
4556 | struct cgroup_subsys_state *css = | |
25e15d83 | 4557 | container_of(work, struct cgroup_subsys_state, destroy_work); |
15a4c835 | 4558 | struct cgroup_subsys *ss = css->ss; |
9d755d33 | 4559 | struct cgroup *cgrp = css->cgroup; |
15a4c835 | 4560 | |
1fed1b2e TH |
4561 | mutex_lock(&cgroup_mutex); |
4562 | ||
de3f0341 | 4563 | css->flags |= CSS_RELEASED; |
1fed1b2e TH |
4564 | list_del_rcu(&css->sibling); |
4565 | ||
9d755d33 TH |
4566 | if (ss) { |
4567 | /* css release path */ | |
01e58659 | 4568 | cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
7d172cc8 TH |
4569 | if (ss->css_released) |
4570 | ss->css_released(css); | |
9d755d33 TH |
4571 | } else { |
4572 | /* cgroup release path */ | |
9d755d33 TH |
4573 | cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
4574 | cgrp->id = -1; | |
a4189487 LZ |
4575 | |
4576 | /* | |
4577 | * There are two control paths which try to determine | |
4578 | * cgroup from dentry without going through kernfs - | |
4579 | * cgroupstats_build() and css_tryget_online_from_dir(). | |
4580 | * Those are supported by RCU protecting clearing of | |
4581 | * cgrp->kn->priv backpointer. | |
4582 | */ | |
4583 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); | |
9d755d33 | 4584 | } |
d3daf28d | 4585 | |
1fed1b2e TH |
4586 | mutex_unlock(&cgroup_mutex); |
4587 | ||
0c21ead1 | 4588 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
4589 | } |
4590 | ||
d3daf28d TH |
4591 | static void css_release(struct percpu_ref *ref) |
4592 | { | |
4593 | struct cgroup_subsys_state *css = | |
4594 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4595 | ||
25e15d83 TH |
4596 | INIT_WORK(&css->destroy_work, css_release_work_fn); |
4597 | queue_work(cgroup_destroy_wq, &css->destroy_work); | |
d3daf28d TH |
4598 | } |
4599 | ||
ddfcadab TH |
4600 | static void init_and_link_css(struct cgroup_subsys_state *css, |
4601 | struct cgroup_subsys *ss, struct cgroup *cgrp) | |
ddbcc7e8 | 4602 | { |
0cb51d71 TH |
4603 | lockdep_assert_held(&cgroup_mutex); |
4604 | ||
ddfcadab TH |
4605 | cgroup_get(cgrp); |
4606 | ||
d5c419b6 | 4607 | memset(css, 0, sizeof(*css)); |
bd89aabc | 4608 | css->cgroup = cgrp; |
72c97e54 | 4609 | css->ss = ss; |
d5c419b6 TH |
4610 | INIT_LIST_HEAD(&css->sibling); |
4611 | INIT_LIST_HEAD(&css->children); | |
0cb51d71 | 4612 | css->serial_nr = css_serial_nr_next++; |
0ae78e0b | 4613 | |
d51f39b0 TH |
4614 | if (cgroup_parent(cgrp)) { |
4615 | css->parent = cgroup_css(cgroup_parent(cgrp), ss); | |
ddfcadab | 4616 | css_get(css->parent); |
ddfcadab | 4617 | } |
48ddbe19 | 4618 | |
ca8bdcaf | 4619 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
4620 | } |
4621 | ||
2a4ac633 | 4622 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 4623 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4624 | { |
623f926b | 4625 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
4626 | int ret = 0; |
4627 | ||
a31f2d3f TH |
4628 | lockdep_assert_held(&cgroup_mutex); |
4629 | ||
92fb9748 | 4630 | if (ss->css_online) |
eb95419b | 4631 | ret = ss->css_online(css); |
ae7f164a | 4632 | if (!ret) { |
eb95419b | 4633 | css->flags |= CSS_ONLINE; |
aec25020 | 4634 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 4635 | } |
b1929db4 | 4636 | return ret; |
a31f2d3f TH |
4637 | } |
4638 | ||
2a4ac633 | 4639 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 4640 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4641 | { |
623f926b | 4642 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f TH |
4643 | |
4644 | lockdep_assert_held(&cgroup_mutex); | |
4645 | ||
4646 | if (!(css->flags & CSS_ONLINE)) | |
4647 | return; | |
4648 | ||
d7eeac19 | 4649 | if (ss->css_offline) |
eb95419b | 4650 | ss->css_offline(css); |
a31f2d3f | 4651 | |
eb95419b | 4652 | css->flags &= ~CSS_ONLINE; |
e3297803 | 4653 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
f8f22e53 TH |
4654 | |
4655 | wake_up_all(&css->cgroup->offline_waitq); | |
a31f2d3f TH |
4656 | } |
4657 | ||
c81c925a TH |
4658 | /** |
4659 | * create_css - create a cgroup_subsys_state | |
4660 | * @cgrp: the cgroup new css will be associated with | |
4661 | * @ss: the subsys of new css | |
f63070d3 | 4662 | * @visible: whether to create control knobs for the new css or not |
c81c925a TH |
4663 | * |
4664 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
f63070d3 TH |
4665 | * css is online and installed in @cgrp with all interface files created if |
4666 | * @visible. Returns 0 on success, -errno on failure. | |
c81c925a | 4667 | */ |
f63070d3 TH |
4668 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
4669 | bool visible) | |
c81c925a | 4670 | { |
d51f39b0 | 4671 | struct cgroup *parent = cgroup_parent(cgrp); |
1fed1b2e | 4672 | struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
c81c925a TH |
4673 | struct cgroup_subsys_state *css; |
4674 | int err; | |
4675 | ||
c81c925a TH |
4676 | lockdep_assert_held(&cgroup_mutex); |
4677 | ||
1fed1b2e | 4678 | css = ss->css_alloc(parent_css); |
c81c925a TH |
4679 | if (IS_ERR(css)) |
4680 | return PTR_ERR(css); | |
4681 | ||
ddfcadab | 4682 | init_and_link_css(css, ss, cgrp); |
a2bed820 | 4683 | |
2aad2a86 | 4684 | err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
c81c925a | 4685 | if (err) |
3eb59ec6 | 4686 | goto err_free_css; |
c81c925a | 4687 | |
cf780b7d | 4688 | err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
15a4c835 TH |
4689 | if (err < 0) |
4690 | goto err_free_percpu_ref; | |
4691 | css->id = err; | |
c81c925a | 4692 | |
f63070d3 TH |
4693 | if (visible) { |
4694 | err = cgroup_populate_dir(cgrp, 1 << ss->id); | |
4695 | if (err) | |
4696 | goto err_free_id; | |
4697 | } | |
15a4c835 TH |
4698 | |
4699 | /* @css is ready to be brought online now, make it visible */ | |
1fed1b2e | 4700 | list_add_tail_rcu(&css->sibling, &parent_css->children); |
15a4c835 | 4701 | cgroup_idr_replace(&ss->css_idr, css, css->id); |
c81c925a TH |
4702 | |
4703 | err = online_css(css); | |
4704 | if (err) | |
1fed1b2e | 4705 | goto err_list_del; |
94419627 | 4706 | |
c81c925a | 4707 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
d51f39b0 | 4708 | cgroup_parent(parent)) { |
ed3d261b | 4709 | pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", |
a2a1f9ea | 4710 | current->comm, current->pid, ss->name); |
c81c925a | 4711 | if (!strcmp(ss->name, "memory")) |
ed3d261b | 4712 | pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
c81c925a TH |
4713 | ss->warned_broken_hierarchy = true; |
4714 | } | |
4715 | ||
4716 | return 0; | |
4717 | ||
1fed1b2e TH |
4718 | err_list_del: |
4719 | list_del_rcu(&css->sibling); | |
32d01dc7 | 4720 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
15a4c835 TH |
4721 | err_free_id: |
4722 | cgroup_idr_remove(&ss->css_idr, css->id); | |
3eb59ec6 | 4723 | err_free_percpu_ref: |
9a1049da | 4724 | percpu_ref_exit(&css->refcnt); |
3eb59ec6 | 4725 | err_free_css: |
a2bed820 | 4726 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
c81c925a TH |
4727 | return err; |
4728 | } | |
4729 | ||
b3bfd983 TH |
4730 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
4731 | umode_t mode) | |
ddbcc7e8 | 4732 | { |
a9746d8d TH |
4733 | struct cgroup *parent, *cgrp; |
4734 | struct cgroup_root *root; | |
ddbcc7e8 | 4735 | struct cgroup_subsys *ss; |
2bd59d48 | 4736 | struct kernfs_node *kn; |
a14c6874 | 4737 | struct cftype *base_files; |
b3bfd983 | 4738 | int ssid, ret; |
ddbcc7e8 | 4739 | |
71b1fb5c AC |
4740 | /* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable. |
4741 | */ | |
4742 | if (strchr(name, '\n')) | |
4743 | return -EINVAL; | |
4744 | ||
a9746d8d TH |
4745 | parent = cgroup_kn_lock_live(parent_kn); |
4746 | if (!parent) | |
4747 | return -ENODEV; | |
4748 | root = parent->root; | |
ddbcc7e8 | 4749 | |
0a950f65 | 4750 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc | 4751 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
ba0f4d76 TH |
4752 | if (!cgrp) { |
4753 | ret = -ENOMEM; | |
4754 | goto out_unlock; | |
0ab02ca8 LZ |
4755 | } |
4756 | ||
2aad2a86 | 4757 | ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
9d755d33 TH |
4758 | if (ret) |
4759 | goto out_free_cgrp; | |
4760 | ||
0ab02ca8 LZ |
4761 | /* |
4762 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
4763 | * a half-baked cgroup. | |
4764 | */ | |
cf780b7d | 4765 | cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
0ab02ca8 | 4766 | if (cgrp->id < 0) { |
ba0f4d76 | 4767 | ret = -ENOMEM; |
9d755d33 | 4768 | goto out_cancel_ref; |
976c06bc TH |
4769 | } |
4770 | ||
cc31edce | 4771 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4772 | |
9d800df1 | 4773 | cgrp->self.parent = &parent->self; |
ba0f4d76 | 4774 | cgrp->root = root; |
ddbcc7e8 | 4775 | |
b6abdb0e LZ |
4776 | if (notify_on_release(parent)) |
4777 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4778 | ||
2260e7fc TH |
4779 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4780 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4781 | |
2bd59d48 | 4782 | /* create the directory */ |
e61734c5 | 4783 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 | 4784 | if (IS_ERR(kn)) { |
ba0f4d76 TH |
4785 | ret = PTR_ERR(kn); |
4786 | goto out_free_id; | |
2bd59d48 TH |
4787 | } |
4788 | cgrp->kn = kn; | |
ddbcc7e8 | 4789 | |
4e139afc | 4790 | /* |
6f30558f TH |
4791 | * This extra ref will be put in cgroup_free_fn() and guarantees |
4792 | * that @cgrp->kn is always accessible. | |
4e139afc | 4793 | */ |
6f30558f | 4794 | kernfs_get(kn); |
ddbcc7e8 | 4795 | |
0cb51d71 | 4796 | cgrp->self.serial_nr = css_serial_nr_next++; |
53fa5261 | 4797 | |
4e139afc | 4798 | /* allocation complete, commit to creation */ |
d5c419b6 | 4799 | list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
3c9c825b | 4800 | atomic_inc(&root->nr_cgrps); |
59f5296b | 4801 | cgroup_get(parent); |
415cf07a | 4802 | |
0d80255e TH |
4803 | /* |
4804 | * @cgrp is now fully operational. If something fails after this | |
4805 | * point, it'll be released via the normal destruction path. | |
4806 | */ | |
6fa4918d | 4807 | cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
4e96ee8e | 4808 | |
ba0f4d76 TH |
4809 | ret = cgroup_kn_set_ugid(kn); |
4810 | if (ret) | |
4811 | goto out_destroy; | |
49957f8e | 4812 | |
a14c6874 TH |
4813 | if (cgroup_on_dfl(cgrp)) |
4814 | base_files = cgroup_dfl_base_files; | |
4815 | else | |
4816 | base_files = cgroup_legacy_base_files; | |
4817 | ||
4818 | ret = cgroup_addrm_files(cgrp, base_files, true); | |
ba0f4d76 TH |
4819 | if (ret) |
4820 | goto out_destroy; | |
628f7cd4 | 4821 | |
9d403e99 | 4822 | /* let's create and online css's */ |
b85d2040 | 4823 | for_each_subsys(ss, ssid) { |
f392e51c | 4824 | if (parent->child_subsys_mask & (1 << ssid)) { |
f63070d3 TH |
4825 | ret = create_css(cgrp, ss, |
4826 | parent->subtree_control & (1 << ssid)); | |
ba0f4d76 TH |
4827 | if (ret) |
4828 | goto out_destroy; | |
b85d2040 | 4829 | } |
a8638030 | 4830 | } |
ddbcc7e8 | 4831 | |
bd53d617 TH |
4832 | /* |
4833 | * On the default hierarchy, a child doesn't automatically inherit | |
667c2491 | 4834 | * subtree_control from the parent. Each is configured manually. |
bd53d617 | 4835 | */ |
667c2491 TH |
4836 | if (!cgroup_on_dfl(cgrp)) { |
4837 | cgrp->subtree_control = parent->subtree_control; | |
4838 | cgroup_refresh_child_subsys_mask(cgrp); | |
4839 | } | |
2bd59d48 | 4840 | |
2bd59d48 | 4841 | kernfs_activate(kn); |
ddbcc7e8 | 4842 | |
ba0f4d76 TH |
4843 | ret = 0; |
4844 | goto out_unlock; | |
ddbcc7e8 | 4845 | |
ba0f4d76 | 4846 | out_free_id: |
6fa4918d | 4847 | cgroup_idr_remove(&root->cgroup_idr, cgrp->id); |
9d755d33 | 4848 | out_cancel_ref: |
9a1049da | 4849 | percpu_ref_exit(&cgrp->self.refcnt); |
ba0f4d76 | 4850 | out_free_cgrp: |
bd89aabc | 4851 | kfree(cgrp); |
ba0f4d76 | 4852 | out_unlock: |
a9746d8d | 4853 | cgroup_kn_unlock(parent_kn); |
ba0f4d76 | 4854 | return ret; |
4b8b47eb | 4855 | |
ba0f4d76 | 4856 | out_destroy: |
4b8b47eb | 4857 | cgroup_destroy_locked(cgrp); |
ba0f4d76 | 4858 | goto out_unlock; |
ddbcc7e8 PM |
4859 | } |
4860 | ||
223dbc38 TH |
4861 | /* |
4862 | * This is called when the refcnt of a css is confirmed to be killed. | |
249f3468 TH |
4863 | * css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
4864 | * initate destruction and put the css ref from kill_css(). | |
223dbc38 TH |
4865 | */ |
4866 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 4867 | { |
223dbc38 TH |
4868 | struct cgroup_subsys_state *css = |
4869 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
d3daf28d | 4870 | |
f20104de | 4871 | mutex_lock(&cgroup_mutex); |
09a503ea | 4872 | offline_css(css); |
f20104de | 4873 | mutex_unlock(&cgroup_mutex); |
09a503ea | 4874 | |
09a503ea | 4875 | css_put(css); |
d3daf28d TH |
4876 | } |
4877 | ||
223dbc38 TH |
4878 | /* css kill confirmation processing requires process context, bounce */ |
4879 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
4880 | { |
4881 | struct cgroup_subsys_state *css = | |
4882 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4883 | ||
223dbc38 | 4884 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 4885 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
4886 | } |
4887 | ||
f392e51c TH |
4888 | /** |
4889 | * kill_css - destroy a css | |
4890 | * @css: css to destroy | |
4891 | * | |
4892 | * This function initiates destruction of @css by removing cgroup interface | |
4893 | * files and putting its base reference. ->css_offline() will be invoked | |
ec903c0c TH |
4894 | * asynchronously once css_tryget_online() is guaranteed to fail and when |
4895 | * the reference count reaches zero, @css will be released. | |
f392e51c TH |
4896 | */ |
4897 | static void kill_css(struct cgroup_subsys_state *css) | |
edae0c33 | 4898 | { |
01f6474c | 4899 | lockdep_assert_held(&cgroup_mutex); |
94419627 | 4900 | |
2bd59d48 TH |
4901 | /* |
4902 | * This must happen before css is disassociated with its cgroup. | |
4903 | * See seq_css() for details. | |
4904 | */ | |
aec25020 | 4905 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3c14f8b4 | 4906 | |
edae0c33 TH |
4907 | /* |
4908 | * Killing would put the base ref, but we need to keep it alive | |
4909 | * until after ->css_offline(). | |
4910 | */ | |
4911 | css_get(css); | |
4912 | ||
4913 | /* | |
4914 | * cgroup core guarantees that, by the time ->css_offline() is | |
4915 | * invoked, no new css reference will be given out via | |
ec903c0c | 4916 | * css_tryget_online(). We can't simply call percpu_ref_kill() and |
edae0c33 TH |
4917 | * proceed to offlining css's because percpu_ref_kill() doesn't |
4918 | * guarantee that the ref is seen as killed on all CPUs on return. | |
4919 | * | |
4920 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
4921 | * css is confirmed to be seen as killed on all CPUs. | |
4922 | */ | |
4923 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
4924 | } |
4925 | ||
4926 | /** | |
4927 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
4928 | * @cgrp: cgroup to be destroyed | |
4929 | * | |
4930 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
4931 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
ec903c0c TH |
4932 | * guarantee that css_tryget_online() won't succeed by the time |
4933 | * ->css_offline() is invoked. To satisfy all the requirements, | |
4934 | * destruction is implemented in the following two steps. | |
d3daf28d TH |
4935 | * |
4936 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
4937 | * userland visible parts and start killing the percpu refcnts of | |
4938 | * css's. Set up so that the next stage will be kicked off once all | |
4939 | * the percpu refcnts are confirmed to be killed. | |
4940 | * | |
4941 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
4942 | * rest of destruction. Once all cgroup references are gone, the | |
4943 | * cgroup is RCU-freed. | |
4944 | * | |
4945 | * This function implements s1. After this step, @cgrp is gone as far as | |
4946 | * the userland is concerned and a new cgroup with the same name may be | |
4947 | * created. As cgroup doesn't care about the names internally, this | |
4948 | * doesn't cause any problem. | |
4949 | */ | |
42809dd4 TH |
4950 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4951 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4952 | { |
2bd59d48 | 4953 | struct cgroup_subsys_state *css; |
ddd69148 | 4954 | bool empty; |
1c6727af | 4955 | int ssid; |
ddbcc7e8 | 4956 | |
42809dd4 TH |
4957 | lockdep_assert_held(&cgroup_mutex); |
4958 | ||
ddd69148 | 4959 | /* |
96d365e0 | 4960 | * css_set_rwsem synchronizes access to ->cset_links and prevents |
89c5509b | 4961 | * @cgrp from being removed while put_css_set() is in progress. |
ddd69148 | 4962 | */ |
96d365e0 | 4963 | down_read(&css_set_rwsem); |
bb78a92f | 4964 | empty = list_empty(&cgrp->cset_links); |
96d365e0 | 4965 | up_read(&css_set_rwsem); |
ddd69148 | 4966 | if (!empty) |
ddbcc7e8 | 4967 | return -EBUSY; |
a043e3b2 | 4968 | |
bb78a92f | 4969 | /* |
d5c419b6 TH |
4970 | * Make sure there's no live children. We can't test emptiness of |
4971 | * ->self.children as dead children linger on it while being | |
4972 | * drained; otherwise, "rmdir parent/child parent" may fail. | |
bb78a92f | 4973 | */ |
f3d46500 | 4974 | if (css_has_online_children(&cgrp->self)) |
bb78a92f HD |
4975 | return -EBUSY; |
4976 | ||
455050d2 TH |
4977 | /* |
4978 | * Mark @cgrp dead. This prevents further task migration and child | |
de3f0341 | 4979 | * creation by disabling cgroup_lock_live_group(). |
455050d2 | 4980 | */ |
184faf32 | 4981 | cgrp->self.flags &= ~CSS_ONLINE; |
ddbcc7e8 | 4982 | |
249f3468 | 4983 | /* initiate massacre of all css's */ |
1c6727af TH |
4984 | for_each_css(css, ssid, cgrp) |
4985 | kill_css(css); | |
455050d2 | 4986 | |
455050d2 | 4987 | /* |
01f6474c TH |
4988 | * Remove @cgrp directory along with the base files. @cgrp has an |
4989 | * extra ref on its kn. | |
f20104de | 4990 | */ |
01f6474c | 4991 | kernfs_remove(cgrp->kn); |
f20104de | 4992 | |
d51f39b0 | 4993 | check_for_release(cgroup_parent(cgrp)); |
2bd59d48 | 4994 | |
249f3468 | 4995 | /* put the base reference */ |
9d755d33 | 4996 | percpu_ref_kill(&cgrp->self.refcnt); |
455050d2 | 4997 | |
ea15f8cc TH |
4998 | return 0; |
4999 | }; | |
5000 | ||
2bd59d48 | 5001 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 5002 | { |
a9746d8d | 5003 | struct cgroup *cgrp; |
2bd59d48 | 5004 | int ret = 0; |
42809dd4 | 5005 | |
a9746d8d TH |
5006 | cgrp = cgroup_kn_lock_live(kn); |
5007 | if (!cgrp) | |
5008 | return 0; | |
42809dd4 | 5009 | |
a9746d8d | 5010 | ret = cgroup_destroy_locked(cgrp); |
2bb566cb | 5011 | |
a9746d8d | 5012 | cgroup_kn_unlock(kn); |
42809dd4 | 5013 | return ret; |
8e3f6541 TH |
5014 | } |
5015 | ||
2bd59d48 TH |
5016 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
5017 | .remount_fs = cgroup_remount, | |
5018 | .show_options = cgroup_show_options, | |
5019 | .mkdir = cgroup_mkdir, | |
5020 | .rmdir = cgroup_rmdir, | |
5021 | .rename = cgroup_rename, | |
5022 | }; | |
5023 | ||
15a4c835 | 5024 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
ddbcc7e8 | 5025 | { |
ddbcc7e8 | 5026 | struct cgroup_subsys_state *css; |
cfe36bde DC |
5027 | |
5028 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 5029 | |
648bb56d TH |
5030 | mutex_lock(&cgroup_mutex); |
5031 | ||
15a4c835 | 5032 | idr_init(&ss->css_idr); |
0adb0704 | 5033 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 5034 | |
3dd06ffa TH |
5035 | /* Create the root cgroup state for this subsystem */ |
5036 | ss->root = &cgrp_dfl_root; | |
5037 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
5038 | /* We don't handle early failures gracefully */ |
5039 | BUG_ON(IS_ERR(css)); | |
ddfcadab | 5040 | init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
3b514d24 TH |
5041 | |
5042 | /* | |
5043 | * Root csses are never destroyed and we can't initialize | |
5044 | * percpu_ref during early init. Disable refcnting. | |
5045 | */ | |
5046 | css->flags |= CSS_NO_REF; | |
5047 | ||
15a4c835 | 5048 | if (early) { |
9395a450 | 5049 | /* allocation can't be done safely during early init */ |
15a4c835 TH |
5050 | css->id = 1; |
5051 | } else { | |
5052 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); | |
5053 | BUG_ON(css->id < 0); | |
5054 | } | |
ddbcc7e8 | 5055 | |
e8d55fde | 5056 | /* Update the init_css_set to contain a subsys |
817929ec | 5057 | * pointer to this state - since the subsystem is |
e8d55fde | 5058 | * newly registered, all tasks and hence the |
3dd06ffa | 5059 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 5060 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 | 5061 | |
cb4a3167 AS |
5062 | have_fork_callback |= (bool)ss->fork << ss->id; |
5063 | have_exit_callback |= (bool)ss->exit << ss->id; | |
7e47682e | 5064 | have_canfork_callback |= (bool)ss->can_fork << ss->id; |
ddbcc7e8 | 5065 | |
e8d55fde LZ |
5066 | /* At system boot, before all subsystems have been |
5067 | * registered, no tasks have been forked, so we don't | |
5068 | * need to invoke fork callbacks here. */ | |
5069 | BUG_ON(!list_empty(&init_task.tasks)); | |
5070 | ||
ae7f164a | 5071 | BUG_ON(online_css(css)); |
a8638030 | 5072 | |
cf5d5941 BB |
5073 | mutex_unlock(&cgroup_mutex); |
5074 | } | |
cf5d5941 | 5075 | |
ddbcc7e8 | 5076 | /** |
a043e3b2 LZ |
5077 | * cgroup_init_early - cgroup initialization at system boot |
5078 | * | |
5079 | * Initialize cgroups at system boot, and initialize any | |
5080 | * subsystems that request early init. | |
ddbcc7e8 PM |
5081 | */ |
5082 | int __init cgroup_init_early(void) | |
5083 | { | |
7b9a6ba5 | 5084 | static struct cgroup_sb_opts __initdata opts; |
30159ec7 | 5085 | struct cgroup_subsys *ss; |
ddbcc7e8 | 5086 | int i; |
30159ec7 | 5087 | |
3dd06ffa | 5088 | init_cgroup_root(&cgrp_dfl_root, &opts); |
3b514d24 TH |
5089 | cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
5090 | ||
a4ea1cc9 | 5091 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 5092 | |
3ed80a62 | 5093 | for_each_subsys(ss, i) { |
aec25020 | 5094 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
5095 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
5096 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 5097 | ss->id, ss->name); |
073219e9 TH |
5098 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
5099 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
5100 | ||
aec25020 | 5101 | ss->id = i; |
073219e9 | 5102 | ss->name = cgroup_subsys_name[i]; |
3e1d2eed TH |
5103 | if (!ss->legacy_name) |
5104 | ss->legacy_name = cgroup_subsys_name[i]; | |
ddbcc7e8 PM |
5105 | |
5106 | if (ss->early_init) | |
15a4c835 | 5107 | cgroup_init_subsys(ss, true); |
ddbcc7e8 PM |
5108 | } |
5109 | return 0; | |
5110 | } | |
5111 | ||
5112 | /** | |
a043e3b2 LZ |
5113 | * cgroup_init - cgroup initialization |
5114 | * | |
5115 | * Register cgroup filesystem and /proc file, and initialize | |
5116 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
5117 | */ |
5118 | int __init cgroup_init(void) | |
5119 | { | |
30159ec7 | 5120 | struct cgroup_subsys *ss; |
0ac801fe | 5121 | unsigned long key; |
172a2c06 | 5122 | int ssid, err; |
ddbcc7e8 | 5123 | |
1ed13287 | 5124 | BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
a14c6874 TH |
5125 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
5126 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); | |
ddbcc7e8 | 5127 | |
54e7b4eb | 5128 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 5129 | |
82fe9b0d TH |
5130 | /* Add init_css_set to the hash table */ |
5131 | key = css_set_hash(init_css_set.subsys); | |
5132 | hash_add(css_set_table, &init_css_set.hlist, key); | |
5133 | ||
3dd06ffa | 5134 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 5135 | |
54e7b4eb TH |
5136 | mutex_unlock(&cgroup_mutex); |
5137 | ||
172a2c06 | 5138 | for_each_subsys(ss, ssid) { |
15a4c835 TH |
5139 | if (ss->early_init) { |
5140 | struct cgroup_subsys_state *css = | |
5141 | init_css_set.subsys[ss->id]; | |
5142 | ||
5143 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, | |
5144 | GFP_KERNEL); | |
5145 | BUG_ON(css->id < 0); | |
5146 | } else { | |
5147 | cgroup_init_subsys(ss, false); | |
5148 | } | |
172a2c06 | 5149 | |
2d8f243a TH |
5150 | list_add_tail(&init_css_set.e_cset_node[ssid], |
5151 | &cgrp_dfl_root.cgrp.e_csets[ssid]); | |
172a2c06 TH |
5152 | |
5153 | /* | |
c731ae1d LZ |
5154 | * Setting dfl_root subsys_mask needs to consider the |
5155 | * disabled flag and cftype registration needs kmalloc, | |
5156 | * both of which aren't available during early_init. | |
172a2c06 | 5157 | */ |
fc5ed1e9 | 5158 | if (!cgroup_ssid_enabled(ssid)) |
a8ddc821 TH |
5159 | continue; |
5160 | ||
5161 | cgrp_dfl_root.subsys_mask |= 1 << ss->id; | |
5162 | ||
5163 | if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes) | |
5164 | ss->dfl_cftypes = ss->legacy_cftypes; | |
5165 | ||
5de4fa13 TH |
5166 | if (!ss->dfl_cftypes) |
5167 | cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id; | |
5168 | ||
a8ddc821 TH |
5169 | if (ss->dfl_cftypes == ss->legacy_cftypes) { |
5170 | WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); | |
5171 | } else { | |
5172 | WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); | |
5173 | WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); | |
c731ae1d | 5174 | } |
295458e6 VD |
5175 | |
5176 | if (ss->bind) | |
5177 | ss->bind(init_css_set.subsys[ssid]); | |
676db4af GKH |
5178 | } |
5179 | ||
f9bb4882 EB |
5180 | err = sysfs_create_mount_point(fs_kobj, "cgroup"); |
5181 | if (err) | |
5182 | return err; | |
676db4af | 5183 | |
ddbcc7e8 | 5184 | err = register_filesystem(&cgroup_fs_type); |
676db4af | 5185 | if (err < 0) { |
f9bb4882 | 5186 | sysfs_remove_mount_point(fs_kobj, "cgroup"); |
2bd59d48 | 5187 | return err; |
676db4af | 5188 | } |
ddbcc7e8 | 5189 | |
46ae220b | 5190 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 5191 | return 0; |
ddbcc7e8 | 5192 | } |
b4f48b63 | 5193 | |
e5fca243 TH |
5194 | static int __init cgroup_wq_init(void) |
5195 | { | |
5196 | /* | |
5197 | * There isn't much point in executing destruction path in | |
5198 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 5199 | * Use 1 for @max_active. |
e5fca243 TH |
5200 | * |
5201 | * We would prefer to do this in cgroup_init() above, but that | |
5202 | * is called before init_workqueues(): so leave this until after. | |
5203 | */ | |
1a11533f | 5204 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 5205 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
5206 | |
5207 | /* | |
5208 | * Used to destroy pidlists and separate to serve as flush domain. | |
5209 | * Cap @max_active to 1 too. | |
5210 | */ | |
5211 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
5212 | 0, 1); | |
5213 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
5214 | ||
e5fca243 TH |
5215 | return 0; |
5216 | } | |
5217 | core_initcall(cgroup_wq_init); | |
5218 | ||
a424316c PM |
5219 | /* |
5220 | * proc_cgroup_show() | |
5221 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
5222 | * - Used for /proc/<pid>/cgroup. | |
a424316c | 5223 | */ |
006f4ac4 ZL |
5224 | int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
5225 | struct pid *pid, struct task_struct *tsk) | |
a424316c | 5226 | { |
e61734c5 | 5227 | char *buf, *path; |
a424316c | 5228 | int retval; |
3dd06ffa | 5229 | struct cgroup_root *root; |
a424316c PM |
5230 | |
5231 | retval = -ENOMEM; | |
e61734c5 | 5232 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
5233 | if (!buf) |
5234 | goto out; | |
5235 | ||
a424316c | 5236 | mutex_lock(&cgroup_mutex); |
96d365e0 | 5237 | down_read(&css_set_rwsem); |
a424316c | 5238 | |
985ed670 | 5239 | for_each_root(root) { |
a424316c | 5240 | struct cgroup_subsys *ss; |
bd89aabc | 5241 | struct cgroup *cgrp; |
b85d2040 | 5242 | int ssid, count = 0; |
a424316c | 5243 | |
a2dd4247 | 5244 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible) |
985ed670 TH |
5245 | continue; |
5246 | ||
2c6ab6d2 | 5247 | seq_printf(m, "%d:", root->hierarchy_id); |
d98817d4 TH |
5248 | if (root != &cgrp_dfl_root) |
5249 | for_each_subsys(ss, ssid) | |
5250 | if (root->subsys_mask & (1 << ssid)) | |
5251 | seq_printf(m, "%s%s", count++ ? "," : "", | |
3e1d2eed | 5252 | ss->legacy_name); |
c6d57f33 PM |
5253 | if (strlen(root->name)) |
5254 | seq_printf(m, "%sname=%s", count ? "," : "", | |
5255 | root->name); | |
a424316c | 5256 | seq_putc(m, ':'); |
7717f7ba | 5257 | cgrp = task_cgroup_from_root(tsk, root); |
e61734c5 TH |
5258 | path = cgroup_path(cgrp, buf, PATH_MAX); |
5259 | if (!path) { | |
5260 | retval = -ENAMETOOLONG; | |
a424316c | 5261 | goto out_unlock; |
e61734c5 TH |
5262 | } |
5263 | seq_puts(m, path); | |
a424316c PM |
5264 | seq_putc(m, '\n'); |
5265 | } | |
5266 | ||
006f4ac4 | 5267 | retval = 0; |
a424316c | 5268 | out_unlock: |
96d365e0 | 5269 | up_read(&css_set_rwsem); |
a424316c | 5270 | mutex_unlock(&cgroup_mutex); |
a424316c PM |
5271 | kfree(buf); |
5272 | out: | |
5273 | return retval; | |
5274 | } | |
5275 | ||
a424316c PM |
5276 | /* Display information about each subsystem and each hierarchy */ |
5277 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
5278 | { | |
30159ec7 | 5279 | struct cgroup_subsys *ss; |
a424316c | 5280 | int i; |
a424316c | 5281 | |
8bab8dde | 5282 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
5283 | /* |
5284 | * ideally we don't want subsystems moving around while we do this. | |
5285 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5286 | * subsys/hierarchy state. | |
5287 | */ | |
a424316c | 5288 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
5289 | |
5290 | for_each_subsys(ss, i) | |
2c6ab6d2 | 5291 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
3e1d2eed | 5292 | ss->legacy_name, ss->root->hierarchy_id, |
fc5ed1e9 TH |
5293 | atomic_read(&ss->root->nr_cgrps), |
5294 | cgroup_ssid_enabled(i)); | |
30159ec7 | 5295 | |
a424316c PM |
5296 | mutex_unlock(&cgroup_mutex); |
5297 | return 0; | |
5298 | } | |
5299 | ||
5300 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5301 | { | |
9dce07f1 | 5302 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5303 | } |
5304 | ||
828c0950 | 5305 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5306 | .open = cgroupstats_open, |
5307 | .read = seq_read, | |
5308 | .llseek = seq_lseek, | |
5309 | .release = single_release, | |
5310 | }; | |
5311 | ||
7e47682e AS |
5312 | static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i) |
5313 | { | |
5314 | if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END) | |
5315 | return &ss_priv[i - CGROUP_CANFORK_START]; | |
5316 | return NULL; | |
5317 | } | |
5318 | ||
5319 | static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i) | |
5320 | { | |
5321 | void **private = subsys_canfork_priv_p(ss_priv, i); | |
5322 | return private ? *private : NULL; | |
5323 | } | |
5324 | ||
b4f48b63 | 5325 | /** |
eaf797ab | 5326 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 5327 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 5328 | * |
eaf797ab TH |
5329 | * A task is associated with the init_css_set until cgroup_post_fork() |
5330 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
5331 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
5332 | */ |
5333 | void cgroup_fork(struct task_struct *child) | |
5334 | { | |
eaf797ab | 5335 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 5336 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5337 | } |
5338 | ||
7e47682e AS |
5339 | /** |
5340 | * cgroup_can_fork - called on a new task before the process is exposed | |
5341 | * @child: the task in question. | |
5342 | * | |
5343 | * This calls the subsystem can_fork() callbacks. If the can_fork() callback | |
5344 | * returns an error, the fork aborts with that error code. This allows for | |
5345 | * a cgroup subsystem to conditionally allow or deny new forks. | |
5346 | */ | |
5347 | int cgroup_can_fork(struct task_struct *child, | |
5348 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5349 | { | |
5350 | struct cgroup_subsys *ss; | |
5351 | int i, j, ret; | |
5352 | ||
5353 | for_each_subsys_which(ss, i, &have_canfork_callback) { | |
5354 | ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i)); | |
5355 | if (ret) | |
5356 | goto out_revert; | |
5357 | } | |
5358 | ||
5359 | return 0; | |
5360 | ||
5361 | out_revert: | |
5362 | for_each_subsys(ss, j) { | |
5363 | if (j >= i) | |
5364 | break; | |
5365 | if (ss->cancel_fork) | |
5366 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j)); | |
5367 | } | |
5368 | ||
5369 | return ret; | |
5370 | } | |
5371 | ||
5372 | /** | |
5373 | * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() | |
5374 | * @child: the task in question | |
5375 | * | |
5376 | * This calls the cancel_fork() callbacks if a fork failed *after* | |
5377 | * cgroup_can_fork() succeded. | |
5378 | */ | |
5379 | void cgroup_cancel_fork(struct task_struct *child, | |
5380 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5381 | { | |
5382 | struct cgroup_subsys *ss; | |
5383 | int i; | |
5384 | ||
5385 | for_each_subsys(ss, i) | |
5386 | if (ss->cancel_fork) | |
5387 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i)); | |
5388 | } | |
5389 | ||
817929ec | 5390 | /** |
a043e3b2 LZ |
5391 | * cgroup_post_fork - called on a new task after adding it to the task list |
5392 | * @child: the task in question | |
5393 | * | |
5edee61e TH |
5394 | * Adds the task to the list running through its css_set if necessary and |
5395 | * call the subsystem fork() callbacks. Has to be after the task is | |
5396 | * visible on the task list in case we race with the first call to | |
0942eeee | 5397 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 5398 | * list. |
a043e3b2 | 5399 | */ |
7e47682e AS |
5400 | void cgroup_post_fork(struct task_struct *child, |
5401 | void *old_ss_priv[CGROUP_CANFORK_COUNT]) | |
817929ec | 5402 | { |
30159ec7 | 5403 | struct cgroup_subsys *ss; |
5edee61e TH |
5404 | int i; |
5405 | ||
3ce3230a | 5406 | /* |
251f8c03 | 5407 | * This may race against cgroup_enable_task_cg_lists(). As that |
eaf797ab TH |
5408 | * function sets use_task_css_set_links before grabbing |
5409 | * tasklist_lock and we just went through tasklist_lock to add | |
5410 | * @child, it's guaranteed that either we see the set | |
5411 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
5412 | * @child during its iteration. | |
5413 | * | |
5414 | * If we won the race, @child is associated with %current's | |
5415 | * css_set. Grabbing css_set_rwsem guarantees both that the | |
5416 | * association is stable, and, on completion of the parent's | |
5417 | * migration, @child is visible in the source of migration or | |
5418 | * already in the destination cgroup. This guarantee is necessary | |
5419 | * when implementing operations which need to migrate all tasks of | |
5420 | * a cgroup to another. | |
5421 | * | |
251f8c03 | 5422 | * Note that if we lose to cgroup_enable_task_cg_lists(), @child |
eaf797ab TH |
5423 | * will remain in init_css_set. This is safe because all tasks are |
5424 | * in the init_css_set before cg_links is enabled and there's no | |
5425 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 5426 | */ |
817929ec | 5427 | if (use_task_css_set_links) { |
eaf797ab TH |
5428 | struct css_set *cset; |
5429 | ||
96d365e0 | 5430 | down_write(&css_set_rwsem); |
0e1d768f | 5431 | cset = task_css_set(current); |
eaf797ab TH |
5432 | if (list_empty(&child->cg_list)) { |
5433 | rcu_assign_pointer(child->cgroups, cset); | |
5434 | list_add(&child->cg_list, &cset->tasks); | |
5435 | get_css_set(cset); | |
5436 | } | |
96d365e0 | 5437 | up_write(&css_set_rwsem); |
817929ec | 5438 | } |
5edee61e TH |
5439 | |
5440 | /* | |
5441 | * Call ss->fork(). This must happen after @child is linked on | |
5442 | * css_set; otherwise, @child might change state between ->fork() | |
5443 | * and addition to css_set. | |
5444 | */ | |
cb4a3167 | 5445 | for_each_subsys_which(ss, i, &have_fork_callback) |
7e47682e | 5446 | ss->fork(child, subsys_canfork_priv(old_ss_priv, i)); |
817929ec | 5447 | } |
5edee61e | 5448 | |
b4f48b63 PM |
5449 | /** |
5450 | * cgroup_exit - detach cgroup from exiting task | |
5451 | * @tsk: pointer to task_struct of exiting process | |
5452 | * | |
5453 | * Description: Detach cgroup from @tsk and release it. | |
5454 | * | |
5455 | * Note that cgroups marked notify_on_release force every task in | |
5456 | * them to take the global cgroup_mutex mutex when exiting. | |
5457 | * This could impact scaling on very large systems. Be reluctant to | |
5458 | * use notify_on_release cgroups where very high task exit scaling | |
5459 | * is required on large systems. | |
5460 | * | |
0e1d768f TH |
5461 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
5462 | * call cgroup_exit() while the task is still competent to handle | |
5463 | * notify_on_release(), then leave the task attached to the root cgroup in | |
5464 | * each hierarchy for the remainder of its exit. No need to bother with | |
5465 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 5466 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 5467 | */ |
1ec41830 | 5468 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 5469 | { |
30159ec7 | 5470 | struct cgroup_subsys *ss; |
5abb8855 | 5471 | struct css_set *cset; |
eaf797ab | 5472 | bool put_cset = false; |
d41d5a01 | 5473 | int i; |
817929ec PM |
5474 | |
5475 | /* | |
0e1d768f TH |
5476 | * Unlink from @tsk from its css_set. As migration path can't race |
5477 | * with us, we can check cg_list without grabbing css_set_rwsem. | |
817929ec PM |
5478 | */ |
5479 | if (!list_empty(&tsk->cg_list)) { | |
96d365e0 | 5480 | down_write(&css_set_rwsem); |
0e1d768f | 5481 | list_del_init(&tsk->cg_list); |
96d365e0 | 5482 | up_write(&css_set_rwsem); |
0e1d768f | 5483 | put_cset = true; |
817929ec PM |
5484 | } |
5485 | ||
b4f48b63 | 5486 | /* Reassign the task to the init_css_set. */ |
a8ad805c TH |
5487 | cset = task_css_set(tsk); |
5488 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 | 5489 | |
cb4a3167 AS |
5490 | /* see cgroup_post_fork() for details */ |
5491 | for_each_subsys_which(ss, i, &have_exit_callback) { | |
5492 | struct cgroup_subsys_state *old_css = cset->subsys[i]; | |
5493 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 5494 | |
cb4a3167 | 5495 | ss->exit(css, old_css, tsk); |
d41d5a01 | 5496 | } |
d41d5a01 | 5497 | |
eaf797ab | 5498 | if (put_cset) |
a25eb52e | 5499 | put_css_set(cset); |
b4f48b63 | 5500 | } |
697f4161 | 5501 | |
bd89aabc | 5502 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5503 | { |
a25eb52e | 5504 | if (notify_on_release(cgrp) && !cgroup_has_tasks(cgrp) && |
971ff493 ZL |
5505 | !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
5506 | schedule_work(&cgrp->release_agent_work); | |
81a6a5cd PM |
5507 | } |
5508 | ||
81a6a5cd PM |
5509 | /* |
5510 | * Notify userspace when a cgroup is released, by running the | |
5511 | * configured release agent with the name of the cgroup (path | |
5512 | * relative to the root of cgroup file system) as the argument. | |
5513 | * | |
5514 | * Most likely, this user command will try to rmdir this cgroup. | |
5515 | * | |
5516 | * This races with the possibility that some other task will be | |
5517 | * attached to this cgroup before it is removed, or that some other | |
5518 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5519 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5520 | * unused, and this cgroup will be reprieved from its death sentence, | |
5521 | * to continue to serve a useful existence. Next time it's released, | |
5522 | * we will get notified again, if it still has 'notify_on_release' set. | |
5523 | * | |
5524 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5525 | * means only wait until the task is successfully execve()'d. The | |
5526 | * separate release agent task is forked by call_usermodehelper(), | |
5527 | * then control in this thread returns here, without waiting for the | |
5528 | * release agent task. We don't bother to wait because the caller of | |
5529 | * this routine has no use for the exit status of the release agent | |
5530 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5531 | */ |
81a6a5cd PM |
5532 | static void cgroup_release_agent(struct work_struct *work) |
5533 | { | |
971ff493 ZL |
5534 | struct cgroup *cgrp = |
5535 | container_of(work, struct cgroup, release_agent_work); | |
5536 | char *pathbuf = NULL, *agentbuf = NULL, *path; | |
5537 | char *argv[3], *envp[3]; | |
5538 | ||
81a6a5cd | 5539 | mutex_lock(&cgroup_mutex); |
971ff493 ZL |
5540 | |
5541 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); | |
5542 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5543 | if (!pathbuf || !agentbuf) | |
5544 | goto out; | |
5545 | ||
5546 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); | |
5547 | if (!path) | |
5548 | goto out; | |
5549 | ||
5550 | argv[0] = agentbuf; | |
5551 | argv[1] = path; | |
5552 | argv[2] = NULL; | |
5553 | ||
5554 | /* minimal command environment */ | |
5555 | envp[0] = "HOME=/"; | |
5556 | envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5557 | envp[2] = NULL; | |
5558 | ||
81a6a5cd | 5559 | mutex_unlock(&cgroup_mutex); |
971ff493 | 5560 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
3e2cd91a | 5561 | goto out_free; |
971ff493 | 5562 | out: |
81a6a5cd | 5563 | mutex_unlock(&cgroup_mutex); |
3e2cd91a | 5564 | out_free: |
971ff493 ZL |
5565 | kfree(agentbuf); |
5566 | kfree(pathbuf); | |
81a6a5cd | 5567 | } |
8bab8dde PM |
5568 | |
5569 | static int __init cgroup_disable(char *str) | |
5570 | { | |
30159ec7 | 5571 | struct cgroup_subsys *ss; |
8bab8dde | 5572 | char *token; |
30159ec7 | 5573 | int i; |
8bab8dde PM |
5574 | |
5575 | while ((token = strsep(&str, ",")) != NULL) { | |
5576 | if (!*token) | |
5577 | continue; | |
be45c900 | 5578 | |
3ed80a62 | 5579 | for_each_subsys(ss, i) { |
3e1d2eed TH |
5580 | if (strcmp(token, ss->name) && |
5581 | strcmp(token, ss->legacy_name)) | |
5582 | continue; | |
5583 | ||
49d1dc4b | 5584 | static_branch_disable(cgroup_subsys_enabled_key[i]); |
3e1d2eed TH |
5585 | printk(KERN_INFO "Disabling %s control group subsystem\n", |
5586 | ss->name); | |
5587 | break; | |
8bab8dde PM |
5588 | } |
5589 | } | |
5590 | return 1; | |
5591 | } | |
5592 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 5593 | |
a8ddc821 TH |
5594 | static int __init cgroup_set_legacy_files_on_dfl(char *str) |
5595 | { | |
5596 | printk("cgroup: using legacy files on the default hierarchy\n"); | |
5597 | cgroup_legacy_files_on_dfl = true; | |
5598 | return 0; | |
5599 | } | |
5600 | __setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl); | |
5601 | ||
b77d7b60 | 5602 | /** |
ec903c0c | 5603 | * css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
35cf0836 TH |
5604 | * @dentry: directory dentry of interest |
5605 | * @ss: subsystem of interest | |
b77d7b60 | 5606 | * |
5a17f543 TH |
5607 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
5608 | * to get the corresponding css and return it. If such css doesn't exist | |
5609 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 5610 | */ |
ec903c0c TH |
5611 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
5612 | struct cgroup_subsys *ss) | |
e5d1367f | 5613 | { |
2bd59d48 TH |
5614 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
5615 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 5616 | struct cgroup *cgrp; |
e5d1367f | 5617 | |
35cf0836 | 5618 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
5619 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
5620 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
5621 | return ERR_PTR(-EBADF); |
5622 | ||
5a17f543 TH |
5623 | rcu_read_lock(); |
5624 | ||
2bd59d48 TH |
5625 | /* |
5626 | * This path doesn't originate from kernfs and @kn could already | |
5627 | * have been or be removed at any point. @kn->priv is RCU | |
a4189487 | 5628 | * protected for this access. See css_release_work_fn() for details. |
2bd59d48 TH |
5629 | */ |
5630 | cgrp = rcu_dereference(kn->priv); | |
5631 | if (cgrp) | |
5632 | css = cgroup_css(cgrp, ss); | |
5a17f543 | 5633 | |
ec903c0c | 5634 | if (!css || !css_tryget_online(css)) |
5a17f543 TH |
5635 | css = ERR_PTR(-ENOENT); |
5636 | ||
5637 | rcu_read_unlock(); | |
5638 | return css; | |
e5d1367f | 5639 | } |
e5d1367f | 5640 | |
1cb650b9 LZ |
5641 | /** |
5642 | * css_from_id - lookup css by id | |
5643 | * @id: the cgroup id | |
5644 | * @ss: cgroup subsys to be looked into | |
5645 | * | |
5646 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
5647 | * Should be called under rcu_read_lock(). | |
5648 | */ | |
5649 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
5650 | { | |
6fa4918d | 5651 | WARN_ON_ONCE(!rcu_read_lock_held()); |
adbe427b | 5652 | return id > 0 ? idr_find(&ss->css_idr, id) : NULL; |
e5d1367f SE |
5653 | } |
5654 | ||
fe693435 | 5655 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
5656 | static struct cgroup_subsys_state * |
5657 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
5658 | { |
5659 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5660 | ||
5661 | if (!css) | |
5662 | return ERR_PTR(-ENOMEM); | |
5663 | ||
5664 | return css; | |
5665 | } | |
5666 | ||
eb95419b | 5667 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 5668 | { |
eb95419b | 5669 | kfree(css); |
fe693435 PM |
5670 | } |
5671 | ||
182446d0 TH |
5672 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
5673 | struct cftype *cft) | |
fe693435 | 5674 | { |
182446d0 | 5675 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
5676 | } |
5677 | ||
182446d0 TH |
5678 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
5679 | struct cftype *cft) | |
fe693435 PM |
5680 | { |
5681 | return (u64)(unsigned long)current->cgroups; | |
5682 | } | |
5683 | ||
182446d0 | 5684 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 5685 | struct cftype *cft) |
fe693435 PM |
5686 | { |
5687 | u64 count; | |
5688 | ||
5689 | rcu_read_lock(); | |
a8ad805c | 5690 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
5691 | rcu_read_unlock(); |
5692 | return count; | |
5693 | } | |
5694 | ||
2da8ca82 | 5695 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5696 | { |
69d0206c | 5697 | struct cgrp_cset_link *link; |
5abb8855 | 5698 | struct css_set *cset; |
e61734c5 TH |
5699 | char *name_buf; |
5700 | ||
5701 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
5702 | if (!name_buf) | |
5703 | return -ENOMEM; | |
7717f7ba | 5704 | |
96d365e0 | 5705 | down_read(&css_set_rwsem); |
7717f7ba | 5706 | rcu_read_lock(); |
5abb8855 | 5707 | cset = rcu_dereference(current->cgroups); |
69d0206c | 5708 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 5709 | struct cgroup *c = link->cgrp; |
7717f7ba | 5710 | |
a2dd4247 | 5711 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 5712 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 5713 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
5714 | } |
5715 | rcu_read_unlock(); | |
96d365e0 | 5716 | up_read(&css_set_rwsem); |
e61734c5 | 5717 | kfree(name_buf); |
7717f7ba PM |
5718 | return 0; |
5719 | } | |
5720 | ||
5721 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 5722 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5723 | { |
2da8ca82 | 5724 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 5725 | struct cgrp_cset_link *link; |
7717f7ba | 5726 | |
96d365e0 | 5727 | down_read(&css_set_rwsem); |
182446d0 | 5728 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 5729 | struct css_set *cset = link->cset; |
7717f7ba PM |
5730 | struct task_struct *task; |
5731 | int count = 0; | |
c7561128 | 5732 | |
5abb8855 | 5733 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 5734 | |
5abb8855 | 5735 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
5736 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
5737 | goto overflow; | |
5738 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
5739 | } | |
5740 | ||
5741 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
5742 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
5743 | goto overflow; | |
5744 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 5745 | } |
c7561128 TH |
5746 | continue; |
5747 | overflow: | |
5748 | seq_puts(seq, " ...\n"); | |
7717f7ba | 5749 | } |
96d365e0 | 5750 | up_read(&css_set_rwsem); |
7717f7ba PM |
5751 | return 0; |
5752 | } | |
5753 | ||
182446d0 | 5754 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 5755 | { |
a25eb52e ZL |
5756 | return (!cgroup_has_tasks(css->cgroup) && |
5757 | !css_has_online_children(&css->cgroup->self)); | |
fe693435 PM |
5758 | } |
5759 | ||
5760 | static struct cftype debug_files[] = { | |
fe693435 PM |
5761 | { |
5762 | .name = "taskcount", | |
5763 | .read_u64 = debug_taskcount_read, | |
5764 | }, | |
5765 | ||
5766 | { | |
5767 | .name = "current_css_set", | |
5768 | .read_u64 = current_css_set_read, | |
5769 | }, | |
5770 | ||
5771 | { | |
5772 | .name = "current_css_set_refcount", | |
5773 | .read_u64 = current_css_set_refcount_read, | |
5774 | }, | |
5775 | ||
7717f7ba PM |
5776 | { |
5777 | .name = "current_css_set_cg_links", | |
2da8ca82 | 5778 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
5779 | }, |
5780 | ||
5781 | { | |
5782 | .name = "cgroup_css_links", | |
2da8ca82 | 5783 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
5784 | }, |
5785 | ||
fe693435 PM |
5786 | { |
5787 | .name = "releasable", | |
5788 | .read_u64 = releasable_read, | |
5789 | }, | |
fe693435 | 5790 | |
4baf6e33 TH |
5791 | { } /* terminate */ |
5792 | }; | |
fe693435 | 5793 | |
073219e9 | 5794 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
5795 | .css_alloc = debug_css_alloc, |
5796 | .css_free = debug_css_free, | |
5577964e | 5797 | .legacy_cftypes = debug_files, |
fe693435 PM |
5798 | }; |
5799 | #endif /* CONFIG_CGROUP_DEBUG */ |