]>
Commit | Line | Data |
---|---|---|
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 | ||
29 | #include <linux/cgroup.h> | |
2ce9738b | 30 | #include <linux/cred.h> |
c6d57f33 | 31 | #include <linux/ctype.h> |
ddbcc7e8 | 32 | #include <linux/errno.h> |
2ce9738b | 33 | #include <linux/init_task.h> |
ddbcc7e8 PM |
34 | #include <linux/kernel.h> |
35 | #include <linux/list.h> | |
36 | #include <linux/mm.h> | |
37 | #include <linux/mutex.h> | |
38 | #include <linux/mount.h> | |
39 | #include <linux/pagemap.h> | |
a424316c | 40 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
41 | #include <linux/rcupdate.h> |
42 | #include <linux/sched.h> | |
ddbcc7e8 | 43 | #include <linux/slab.h> |
ddbcc7e8 | 44 | #include <linux/spinlock.h> |
96d365e0 | 45 | #include <linux/rwsem.h> |
ddbcc7e8 | 46 | #include <linux/string.h> |
bbcb81d0 | 47 | #include <linux/sort.h> |
81a6a5cd | 48 | #include <linux/kmod.h> |
846c7bb0 BS |
49 | #include <linux/delayacct.h> |
50 | #include <linux/cgroupstats.h> | |
0ac801fe | 51 | #include <linux/hashtable.h> |
096b7fe0 | 52 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 53 | #include <linux/idr.h> |
d1d9fd33 | 54 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 55 | #include <linux/kthread.h> |
776f02fa | 56 | #include <linux/delay.h> |
846c7bb0 | 57 | |
60063497 | 58 | #include <linux/atomic.h> |
ddbcc7e8 | 59 | |
b1a21367 TH |
60 | /* |
61 | * pidlists linger the following amount before being destroyed. The goal | |
62 | * is avoiding frequent destruction in the middle of consecutive read calls | |
63 | * Expiring in the middle is a performance problem not a correctness one. | |
64 | * 1 sec should be enough. | |
65 | */ | |
66 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
67 | ||
8d7e6fb0 TH |
68 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
69 | MAX_CFTYPE_NAME + 2) | |
70 | ||
ace2bee8 TH |
71 | /* |
72 | * cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file | |
73 | * creation/removal and hierarchy changing operations including cgroup | |
74 | * creation, removal, css association and controller rebinding. This outer | |
75 | * lock is needed mainly to resolve the circular dependency between kernfs | |
76 | * active ref and cgroup_mutex. cgroup_tree_mutex nests above both. | |
77 | */ | |
78 | static DEFINE_MUTEX(cgroup_tree_mutex); | |
79 | ||
e25e2cbb TH |
80 | /* |
81 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
82 | * hierarchy must be performed while holding it. | |
83 | * | |
0e1d768f TH |
84 | * css_set_rwsem protects task->cgroups pointer, the list of css_set |
85 | * objects, and the chain of tasks off each css_set. | |
e25e2cbb | 86 | * |
0e1d768f TH |
87 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
88 | * cgroup.h can use them for lockdep annotations. | |
e25e2cbb | 89 | */ |
2219449a TH |
90 | #ifdef CONFIG_PROVE_RCU |
91 | DEFINE_MUTEX(cgroup_mutex); | |
0e1d768f TH |
92 | DECLARE_RWSEM(css_set_rwsem); |
93 | EXPORT_SYMBOL_GPL(cgroup_mutex); | |
94 | EXPORT_SYMBOL_GPL(css_set_rwsem); | |
2219449a | 95 | #else |
81a6a5cd | 96 | static DEFINE_MUTEX(cgroup_mutex); |
0e1d768f | 97 | static DECLARE_RWSEM(css_set_rwsem); |
2219449a TH |
98 | #endif |
99 | ||
69e943b7 TH |
100 | /* |
101 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
102 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
103 | */ | |
104 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
81a6a5cd | 105 | |
ace2bee8 | 106 | #define cgroup_assert_mutexes_or_rcu_locked() \ |
87fb54f1 | 107 | rcu_lockdep_assert(rcu_read_lock_held() || \ |
ace2bee8 | 108 | lockdep_is_held(&cgroup_tree_mutex) || \ |
87fb54f1 | 109 | lockdep_is_held(&cgroup_mutex), \ |
ace2bee8 | 110 | "cgroup_[tree_]mutex or RCU read lock required"); |
780cd8b3 | 111 | |
e5fca243 TH |
112 | /* |
113 | * cgroup destruction makes heavy use of work items and there can be a lot | |
114 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
115 | * destruction work items don't end up filling up max_active of system_wq | |
116 | * which may lead to deadlock. | |
117 | */ | |
118 | static struct workqueue_struct *cgroup_destroy_wq; | |
119 | ||
b1a21367 TH |
120 | /* |
121 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
122 | * separate workqueue as flush domain. | |
123 | */ | |
124 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
125 | ||
3ed80a62 | 126 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 127 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 128 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
129 | #include <linux/cgroup_subsys.h> |
130 | }; | |
073219e9 TH |
131 | #undef SUBSYS |
132 | ||
133 | /* array of cgroup subsystem names */ | |
134 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
135 | static const char *cgroup_subsys_name[] = { | |
ddbcc7e8 PM |
136 | #include <linux/cgroup_subsys.h> |
137 | }; | |
073219e9 | 138 | #undef SUBSYS |
ddbcc7e8 | 139 | |
ddbcc7e8 | 140 | /* |
3dd06ffa | 141 | * The default hierarchy, reserved for the subsystems that are otherwise |
9871bf95 TH |
142 | * unattached - it never has more than a single cgroup, and all tasks are |
143 | * part of that cgroup. | |
ddbcc7e8 | 144 | */ |
a2dd4247 | 145 | struct cgroup_root cgrp_dfl_root; |
9871bf95 | 146 | |
a2dd4247 TH |
147 | /* |
148 | * The default hierarchy always exists but is hidden until mounted for the | |
149 | * first time. This is for backward compatibility. | |
150 | */ | |
151 | static bool cgrp_dfl_root_visible; | |
ddbcc7e8 PM |
152 | |
153 | /* The list of hierarchy roots */ | |
154 | ||
9871bf95 TH |
155 | static LIST_HEAD(cgroup_roots); |
156 | static int cgroup_root_count; | |
ddbcc7e8 | 157 | |
3417ae1f | 158 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 159 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 160 | |
794611a1 LZ |
161 | /* |
162 | * Assign a monotonically increasing serial number to cgroups. It | |
163 | * guarantees cgroups with bigger numbers are newer than those with smaller | |
164 | * numbers. Also, as cgroups are always appended to the parent's | |
165 | * ->children list, it guarantees that sibling cgroups are always sorted in | |
00356bd5 TH |
166 | * the ascending serial number order on the list. Protected by |
167 | * cgroup_mutex. | |
794611a1 | 168 | */ |
00356bd5 | 169 | static u64 cgroup_serial_nr_next = 1; |
794611a1 | 170 | |
ddbcc7e8 | 171 | /* This flag indicates whether tasks in the fork and exit paths should |
a043e3b2 LZ |
172 | * check for fork/exit handlers to call. This avoids us having to do |
173 | * extra work in the fork/exit path if none of the subsystems need to | |
174 | * be called. | |
ddbcc7e8 | 175 | */ |
8947f9d5 | 176 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 177 | |
628f7cd4 TH |
178 | static struct cftype cgroup_base_files[]; |
179 | ||
59f5296b | 180 | static void cgroup_put(struct cgroup *cgrp); |
3dd06ffa | 181 | static int rebind_subsystems(struct cgroup_root *dst_root, |
5df36032 | 182 | unsigned long ss_mask); |
f20104de | 183 | static void cgroup_destroy_css_killed(struct cgroup *cgrp); |
42809dd4 | 184 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
2bb566cb TH |
185 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
186 | bool is_add); | |
b1a21367 | 187 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp); |
42809dd4 | 188 | |
95109b62 TH |
189 | /** |
190 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
191 | * @cgrp: the cgroup of interest | |
ca8bdcaf | 192 | * @ss: the subsystem of interest (%NULL returns the dummy_css) |
95109b62 | 193 | * |
ca8bdcaf TH |
194 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
195 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
196 | * the caller is responsible for pinning the returned css if it wants to | |
197 | * keep accessing it outside the said locks. This function may return | |
198 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
199 | */ |
200 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 201 | struct cgroup_subsys *ss) |
95109b62 | 202 | { |
ca8bdcaf | 203 | if (ss) |
aec25020 | 204 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 TH |
205 | lockdep_is_held(&cgroup_tree_mutex) || |
206 | lockdep_is_held(&cgroup_mutex)); | |
ca8bdcaf TH |
207 | else |
208 | return &cgrp->dummy_css; | |
95109b62 | 209 | } |
42809dd4 | 210 | |
aec3dfcb TH |
211 | /** |
212 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem | |
213 | * @cgrp: the cgroup of interest | |
214 | * @ss: the subsystem of interest (%NULL returns the dummy_css) | |
215 | * | |
216 | * Similar to cgroup_css() but returns the effctive css, which is defined | |
217 | * as the matching css of the nearest ancestor including self which has @ss | |
218 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this | |
219 | * function is guaranteed to return non-NULL css. | |
220 | */ | |
221 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, | |
222 | struct cgroup_subsys *ss) | |
223 | { | |
224 | lockdep_assert_held(&cgroup_mutex); | |
225 | ||
226 | if (!ss) | |
227 | return &cgrp->dummy_css; | |
228 | ||
229 | if (!(cgrp->root->subsys_mask & (1 << ss->id))) | |
230 | return NULL; | |
231 | ||
232 | while (cgrp->parent && | |
233 | !(cgrp->parent->child_subsys_mask & (1 << ss->id))) | |
234 | cgrp = cgrp->parent; | |
235 | ||
236 | return cgroup_css(cgrp, ss); | |
237 | } | |
238 | ||
ddbcc7e8 | 239 | /* convenient tests for these bits */ |
54766d4a | 240 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 241 | { |
54766d4a | 242 | return test_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 PM |
243 | } |
244 | ||
59f5296b TH |
245 | struct cgroup_subsys_state *seq_css(struct seq_file *seq) |
246 | { | |
2bd59d48 TH |
247 | struct kernfs_open_file *of = seq->private; |
248 | struct cgroup *cgrp = of->kn->parent->priv; | |
249 | struct cftype *cft = seq_cft(seq); | |
250 | ||
251 | /* | |
252 | * This is open and unprotected implementation of cgroup_css(). | |
253 | * seq_css() is only called from a kernfs file operation which has | |
254 | * an active reference on the file. Because all the subsystem | |
255 | * files are drained before a css is disassociated with a cgroup, | |
256 | * the matching css from the cgroup's subsys table is guaranteed to | |
257 | * be and stay valid until the enclosing operation is complete. | |
258 | */ | |
259 | if (cft->ss) | |
260 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
261 | else | |
262 | return &cgrp->dummy_css; | |
59f5296b TH |
263 | } |
264 | EXPORT_SYMBOL_GPL(seq_css); | |
265 | ||
78574cf9 LZ |
266 | /** |
267 | * cgroup_is_descendant - test ancestry | |
268 | * @cgrp: the cgroup to be tested | |
269 | * @ancestor: possible ancestor of @cgrp | |
270 | * | |
271 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
272 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
273 | * and @ancestor are accessible. | |
274 | */ | |
275 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
276 | { | |
277 | while (cgrp) { | |
278 | if (cgrp == ancestor) | |
279 | return true; | |
280 | cgrp = cgrp->parent; | |
281 | } | |
282 | return false; | |
283 | } | |
ddbcc7e8 | 284 | |
e9685a03 | 285 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
286 | { |
287 | const int bits = | |
bd89aabc PM |
288 | (1 << CGRP_RELEASABLE) | |
289 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
290 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
291 | } |
292 | ||
e9685a03 | 293 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 294 | { |
bd89aabc | 295 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
296 | } |
297 | ||
1c6727af TH |
298 | /** |
299 | * for_each_css - iterate all css's of a cgroup | |
300 | * @css: the iteration cursor | |
301 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
302 | * @cgrp: the target cgroup to iterate css's of | |
303 | * | |
aec3dfcb | 304 | * Should be called under cgroup_[tree_]mutex. |
1c6727af TH |
305 | */ |
306 | #define for_each_css(css, ssid, cgrp) \ | |
307 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
308 | if (!((css) = rcu_dereference_check( \ | |
309 | (cgrp)->subsys[(ssid)], \ | |
ace2bee8 | 310 | lockdep_is_held(&cgroup_tree_mutex) || \ |
1c6727af TH |
311 | lockdep_is_held(&cgroup_mutex)))) { } \ |
312 | else | |
313 | ||
aec3dfcb TH |
314 | /** |
315 | * for_each_e_css - iterate all effective css's of a cgroup | |
316 | * @css: the iteration cursor | |
317 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
318 | * @cgrp: the target cgroup to iterate css's of | |
319 | * | |
320 | * Should be called under cgroup_[tree_]mutex. | |
321 | */ | |
322 | #define for_each_e_css(css, ssid, cgrp) \ | |
323 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
324 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ | |
325 | ; \ | |
326 | else | |
327 | ||
30159ec7 | 328 | /** |
3ed80a62 | 329 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 330 | * @ss: the iteration cursor |
780cd8b3 | 331 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 332 | */ |
780cd8b3 | 333 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
334 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
335 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 336 | |
985ed670 TH |
337 | /* iterate across the hierarchies */ |
338 | #define for_each_root(root) \ | |
5549c497 | 339 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 340 | |
7ae1bad9 TH |
341 | /** |
342 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
343 | * @cgrp: the cgroup to be checked for liveness | |
344 | * | |
47cfcd09 TH |
345 | * On success, returns true; the mutex should be later unlocked. On |
346 | * failure returns false with no lock held. | |
7ae1bad9 | 347 | */ |
b9777cf8 | 348 | static bool cgroup_lock_live_group(struct cgroup *cgrp) |
7ae1bad9 TH |
349 | { |
350 | mutex_lock(&cgroup_mutex); | |
54766d4a | 351 | if (cgroup_is_dead(cgrp)) { |
7ae1bad9 TH |
352 | mutex_unlock(&cgroup_mutex); |
353 | return false; | |
354 | } | |
355 | return true; | |
356 | } | |
7ae1bad9 | 357 | |
81a6a5cd PM |
358 | /* the list of cgroups eligible for automatic release. Protected by |
359 | * release_list_lock */ | |
360 | static LIST_HEAD(release_list); | |
cdcc136f | 361 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
362 | static void cgroup_release_agent(struct work_struct *work); |
363 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 364 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 365 | |
69d0206c TH |
366 | /* |
367 | * A cgroup can be associated with multiple css_sets as different tasks may | |
368 | * belong to different cgroups on different hierarchies. In the other | |
369 | * direction, a css_set is naturally associated with multiple cgroups. | |
370 | * This M:N relationship is represented by the following link structure | |
371 | * which exists for each association and allows traversing the associations | |
372 | * from both sides. | |
373 | */ | |
374 | struct cgrp_cset_link { | |
375 | /* the cgroup and css_set this link associates */ | |
376 | struct cgroup *cgrp; | |
377 | struct css_set *cset; | |
378 | ||
379 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
380 | struct list_head cset_link; | |
381 | ||
382 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
383 | struct list_head cgrp_link; | |
817929ec PM |
384 | }; |
385 | ||
172a2c06 TH |
386 | /* |
387 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
388 | * hierarchies being mounted. It contains a pointer to the root state |
389 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
390 | * reference-counted, to improve performance when child cgroups | |
391 | * haven't been created. | |
392 | */ | |
172a2c06 TH |
393 | static struct css_set init_css_set = { |
394 | .refcount = ATOMIC_INIT(1), | |
395 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
396 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
397 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
398 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
399 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
400 | }; | |
817929ec | 401 | |
172a2c06 | 402 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 403 | |
7717f7ba PM |
404 | /* |
405 | * hash table for cgroup groups. This improves the performance to find | |
406 | * an existing css_set. This hash doesn't (currently) take into | |
407 | * account cgroups in empty hierarchies. | |
408 | */ | |
472b1053 | 409 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 410 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 411 | |
0ac801fe | 412 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 413 | { |
0ac801fe | 414 | unsigned long key = 0UL; |
30159ec7 TH |
415 | struct cgroup_subsys *ss; |
416 | int i; | |
472b1053 | 417 | |
30159ec7 | 418 | for_each_subsys(ss, i) |
0ac801fe LZ |
419 | key += (unsigned long)css[i]; |
420 | key = (key >> 16) ^ key; | |
472b1053 | 421 | |
0ac801fe | 422 | return key; |
472b1053 LZ |
423 | } |
424 | ||
89c5509b | 425 | static void put_css_set_locked(struct css_set *cset, bool taskexit) |
b4f48b63 | 426 | { |
69d0206c | 427 | struct cgrp_cset_link *link, *tmp_link; |
2d8f243a TH |
428 | struct cgroup_subsys *ss; |
429 | int ssid; | |
5abb8855 | 430 | |
89c5509b TH |
431 | lockdep_assert_held(&css_set_rwsem); |
432 | ||
433 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 434 | return; |
81a6a5cd | 435 | |
2c6ab6d2 | 436 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
2d8f243a TH |
437 | for_each_subsys(ss, ssid) |
438 | list_del(&cset->e_cset_node[ssid]); | |
5abb8855 | 439 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
440 | css_set_count--; |
441 | ||
69d0206c | 442 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 443 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 444 | |
69d0206c TH |
445 | list_del(&link->cset_link); |
446 | list_del(&link->cgrp_link); | |
71b5707e | 447 | |
96d365e0 | 448 | /* @cgrp can't go away while we're holding css_set_rwsem */ |
6f3d828f | 449 | if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { |
81a6a5cd | 450 | if (taskexit) |
bd89aabc PM |
451 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
452 | check_for_release(cgrp); | |
81a6a5cd | 453 | } |
2c6ab6d2 PM |
454 | |
455 | kfree(link); | |
81a6a5cd | 456 | } |
2c6ab6d2 | 457 | |
5abb8855 | 458 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
459 | } |
460 | ||
89c5509b TH |
461 | static void put_css_set(struct css_set *cset, bool taskexit) |
462 | { | |
463 | /* | |
464 | * Ensure that the refcount doesn't hit zero while any readers | |
465 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
466 | * rwlock | |
467 | */ | |
468 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
469 | return; | |
470 | ||
471 | down_write(&css_set_rwsem); | |
472 | put_css_set_locked(cset, taskexit); | |
473 | up_write(&css_set_rwsem); | |
474 | } | |
475 | ||
817929ec PM |
476 | /* |
477 | * refcounted get/put for css_set objects | |
478 | */ | |
5abb8855 | 479 | static inline void get_css_set(struct css_set *cset) |
817929ec | 480 | { |
5abb8855 | 481 | atomic_inc(&cset->refcount); |
817929ec PM |
482 | } |
483 | ||
b326f9d0 | 484 | /** |
7717f7ba | 485 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
486 | * @cset: candidate css_set being tested |
487 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
488 | * @new_cgrp: cgroup that's being entered by the task |
489 | * @template: desired set of css pointers in css_set (pre-calculated) | |
490 | * | |
6f4b7e63 | 491 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
492 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
493 | */ | |
5abb8855 TH |
494 | static bool compare_css_sets(struct css_set *cset, |
495 | struct css_set *old_cset, | |
7717f7ba PM |
496 | struct cgroup *new_cgrp, |
497 | struct cgroup_subsys_state *template[]) | |
498 | { | |
499 | struct list_head *l1, *l2; | |
500 | ||
aec3dfcb TH |
501 | /* |
502 | * On the default hierarchy, there can be csets which are | |
503 | * associated with the same set of cgroups but different csses. | |
504 | * Let's first ensure that csses match. | |
505 | */ | |
506 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) | |
7717f7ba | 507 | return false; |
7717f7ba PM |
508 | |
509 | /* | |
510 | * Compare cgroup pointers in order to distinguish between | |
aec3dfcb TH |
511 | * different cgroups in hierarchies. As different cgroups may |
512 | * share the same effective css, this comparison is always | |
513 | * necessary. | |
7717f7ba | 514 | */ |
69d0206c TH |
515 | l1 = &cset->cgrp_links; |
516 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 517 | while (1) { |
69d0206c | 518 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 519 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
520 | |
521 | l1 = l1->next; | |
522 | l2 = l2->next; | |
523 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
524 | if (l1 == &cset->cgrp_links) { |
525 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
526 | break; |
527 | } else { | |
69d0206c | 528 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
529 | } |
530 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
531 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
532 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
533 | cgrp1 = link1->cgrp; | |
534 | cgrp2 = link2->cgrp; | |
7717f7ba | 535 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 536 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
537 | |
538 | /* | |
539 | * If this hierarchy is the hierarchy of the cgroup | |
540 | * that's changing, then we need to check that this | |
541 | * css_set points to the new cgroup; if it's any other | |
542 | * hierarchy, then this css_set should point to the | |
543 | * same cgroup as the old css_set. | |
544 | */ | |
5abb8855 TH |
545 | if (cgrp1->root == new_cgrp->root) { |
546 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
547 | return false; |
548 | } else { | |
5abb8855 | 549 | if (cgrp1 != cgrp2) |
7717f7ba PM |
550 | return false; |
551 | } | |
552 | } | |
553 | return true; | |
554 | } | |
555 | ||
b326f9d0 TH |
556 | /** |
557 | * find_existing_css_set - init css array and find the matching css_set | |
558 | * @old_cset: the css_set that we're using before the cgroup transition | |
559 | * @cgrp: the cgroup that we're moving into | |
560 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 561 | */ |
5abb8855 TH |
562 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
563 | struct cgroup *cgrp, | |
564 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 565 | { |
3dd06ffa | 566 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 567 | struct cgroup_subsys *ss; |
5abb8855 | 568 | struct css_set *cset; |
0ac801fe | 569 | unsigned long key; |
b326f9d0 | 570 | int i; |
817929ec | 571 | |
aae8aab4 BB |
572 | /* |
573 | * Build the set of subsystem state objects that we want to see in the | |
574 | * new css_set. while subsystems can change globally, the entries here | |
575 | * won't change, so no need for locking. | |
576 | */ | |
30159ec7 | 577 | for_each_subsys(ss, i) { |
f392e51c | 578 | if (root->subsys_mask & (1UL << i)) { |
aec3dfcb TH |
579 | /* |
580 | * @ss is in this hierarchy, so we want the | |
581 | * effective css from @cgrp. | |
582 | */ | |
583 | template[i] = cgroup_e_css(cgrp, ss); | |
817929ec | 584 | } else { |
aec3dfcb TH |
585 | /* |
586 | * @ss is not in this hierarchy, so we don't want | |
587 | * to change the css. | |
588 | */ | |
5abb8855 | 589 | template[i] = old_cset->subsys[i]; |
817929ec PM |
590 | } |
591 | } | |
592 | ||
0ac801fe | 593 | key = css_set_hash(template); |
5abb8855 TH |
594 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
595 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
596 | continue; |
597 | ||
598 | /* This css_set matches what we need */ | |
5abb8855 | 599 | return cset; |
472b1053 | 600 | } |
817929ec PM |
601 | |
602 | /* No existing cgroup group matched */ | |
603 | return NULL; | |
604 | } | |
605 | ||
69d0206c | 606 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 607 | { |
69d0206c | 608 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 609 | |
69d0206c TH |
610 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
611 | list_del(&link->cset_link); | |
36553434 LZ |
612 | kfree(link); |
613 | } | |
614 | } | |
615 | ||
69d0206c TH |
616 | /** |
617 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
618 | * @count: the number of links to allocate | |
619 | * @tmp_links: list_head the allocated links are put on | |
620 | * | |
621 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
622 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 623 | */ |
69d0206c | 624 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 625 | { |
69d0206c | 626 | struct cgrp_cset_link *link; |
817929ec | 627 | int i; |
69d0206c TH |
628 | |
629 | INIT_LIST_HEAD(tmp_links); | |
630 | ||
817929ec | 631 | for (i = 0; i < count; i++) { |
f4f4be2b | 632 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 633 | if (!link) { |
69d0206c | 634 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
635 | return -ENOMEM; |
636 | } | |
69d0206c | 637 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
638 | } |
639 | return 0; | |
640 | } | |
641 | ||
c12f65d4 LZ |
642 | /** |
643 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 644 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 645 | * @cset: the css_set to be linked |
c12f65d4 LZ |
646 | * @cgrp: the destination cgroup |
647 | */ | |
69d0206c TH |
648 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
649 | struct cgroup *cgrp) | |
c12f65d4 | 650 | { |
69d0206c | 651 | struct cgrp_cset_link *link; |
c12f65d4 | 652 | |
69d0206c TH |
653 | BUG_ON(list_empty(tmp_links)); |
654 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); | |
655 | link->cset = cset; | |
7717f7ba | 656 | link->cgrp = cgrp; |
69d0206c | 657 | list_move(&link->cset_link, &cgrp->cset_links); |
7717f7ba PM |
658 | /* |
659 | * Always add links to the tail of the list so that the list | |
660 | * is sorted by order of hierarchy creation | |
661 | */ | |
69d0206c | 662 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
663 | } |
664 | ||
b326f9d0 TH |
665 | /** |
666 | * find_css_set - return a new css_set with one cgroup updated | |
667 | * @old_cset: the baseline css_set | |
668 | * @cgrp: the cgroup to be updated | |
669 | * | |
670 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
671 | * substituted into the appropriate hierarchy. | |
817929ec | 672 | */ |
5abb8855 TH |
673 | static struct css_set *find_css_set(struct css_set *old_cset, |
674 | struct cgroup *cgrp) | |
817929ec | 675 | { |
b326f9d0 | 676 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 677 | struct css_set *cset; |
69d0206c TH |
678 | struct list_head tmp_links; |
679 | struct cgrp_cset_link *link; | |
2d8f243a | 680 | struct cgroup_subsys *ss; |
0ac801fe | 681 | unsigned long key; |
2d8f243a | 682 | int ssid; |
472b1053 | 683 | |
b326f9d0 TH |
684 | lockdep_assert_held(&cgroup_mutex); |
685 | ||
817929ec PM |
686 | /* First see if we already have a cgroup group that matches |
687 | * the desired set */ | |
96d365e0 | 688 | down_read(&css_set_rwsem); |
5abb8855 TH |
689 | cset = find_existing_css_set(old_cset, cgrp, template); |
690 | if (cset) | |
691 | get_css_set(cset); | |
96d365e0 | 692 | up_read(&css_set_rwsem); |
817929ec | 693 | |
5abb8855 TH |
694 | if (cset) |
695 | return cset; | |
817929ec | 696 | |
f4f4be2b | 697 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 698 | if (!cset) |
817929ec PM |
699 | return NULL; |
700 | ||
69d0206c | 701 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 702 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 703 | kfree(cset); |
817929ec PM |
704 | return NULL; |
705 | } | |
706 | ||
5abb8855 | 707 | atomic_set(&cset->refcount, 1); |
69d0206c | 708 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 709 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 710 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 711 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 712 | INIT_LIST_HEAD(&cset->mg_node); |
5abb8855 | 713 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
714 | |
715 | /* Copy the set of subsystem state objects generated in | |
716 | * find_existing_css_set() */ | |
5abb8855 | 717 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 718 | |
96d365e0 | 719 | down_write(&css_set_rwsem); |
817929ec | 720 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 721 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 722 | struct cgroup *c = link->cgrp; |
69d0206c | 723 | |
7717f7ba PM |
724 | if (c->root == cgrp->root) |
725 | c = cgrp; | |
69d0206c | 726 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 727 | } |
817929ec | 728 | |
69d0206c | 729 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 730 | |
817929ec | 731 | css_set_count++; |
472b1053 | 732 | |
2d8f243a | 733 | /* Add @cset to the hash table */ |
5abb8855 TH |
734 | key = css_set_hash(cset->subsys); |
735 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 736 | |
2d8f243a TH |
737 | for_each_subsys(ss, ssid) |
738 | list_add_tail(&cset->e_cset_node[ssid], | |
739 | &cset->subsys[ssid]->cgroup->e_csets[ssid]); | |
740 | ||
96d365e0 | 741 | up_write(&css_set_rwsem); |
817929ec | 742 | |
5abb8855 | 743 | return cset; |
b4f48b63 PM |
744 | } |
745 | ||
3dd06ffa | 746 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 747 | { |
3dd06ffa | 748 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 749 | |
3dd06ffa | 750 | return root_cgrp->root; |
2bd59d48 TH |
751 | } |
752 | ||
3dd06ffa | 753 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
754 | { |
755 | int id; | |
756 | ||
757 | lockdep_assert_held(&cgroup_mutex); | |
758 | ||
985ed670 | 759 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
760 | if (id < 0) |
761 | return id; | |
762 | ||
763 | root->hierarchy_id = id; | |
764 | return 0; | |
765 | } | |
766 | ||
3dd06ffa | 767 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
768 | { |
769 | lockdep_assert_held(&cgroup_mutex); | |
770 | ||
771 | if (root->hierarchy_id) { | |
772 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
773 | root->hierarchy_id = 0; | |
774 | } | |
775 | } | |
776 | ||
3dd06ffa | 777 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
778 | { |
779 | if (root) { | |
780 | /* hierarhcy ID shoulid already have been released */ | |
781 | WARN_ON_ONCE(root->hierarchy_id); | |
782 | ||
783 | idr_destroy(&root->cgroup_idr); | |
784 | kfree(root); | |
785 | } | |
786 | } | |
787 | ||
3dd06ffa | 788 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 789 | { |
3dd06ffa | 790 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 791 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 792 | |
2bd59d48 | 793 | mutex_lock(&cgroup_tree_mutex); |
2bd59d48 | 794 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 795 | |
776f02fa | 796 | BUG_ON(atomic_read(&root->nr_cgrps)); |
f2e85d57 TH |
797 | BUG_ON(!list_empty(&cgrp->children)); |
798 | ||
f2e85d57 | 799 | /* Rebind all subsystems back to the default hierarchy */ |
f392e51c | 800 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); |
7717f7ba | 801 | |
7717f7ba | 802 | /* |
f2e85d57 TH |
803 | * Release all the links from cset_links to this hierarchy's |
804 | * root cgroup | |
7717f7ba | 805 | */ |
96d365e0 | 806 | down_write(&css_set_rwsem); |
f2e85d57 TH |
807 | |
808 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
809 | list_del(&link->cset_link); | |
810 | list_del(&link->cgrp_link); | |
811 | kfree(link); | |
812 | } | |
96d365e0 | 813 | up_write(&css_set_rwsem); |
f2e85d57 TH |
814 | |
815 | if (!list_empty(&root->root_list)) { | |
816 | list_del(&root->root_list); | |
817 | cgroup_root_count--; | |
818 | } | |
819 | ||
820 | cgroup_exit_root_id(root); | |
821 | ||
822 | mutex_unlock(&cgroup_mutex); | |
823 | mutex_unlock(&cgroup_tree_mutex); | |
f2e85d57 | 824 | |
2bd59d48 | 825 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
826 | cgroup_free_root(root); |
827 | } | |
828 | ||
ceb6a081 TH |
829 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
830 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 831 | struct cgroup_root *root) |
7717f7ba | 832 | { |
7717f7ba PM |
833 | struct cgroup *res = NULL; |
834 | ||
96d365e0 TH |
835 | lockdep_assert_held(&cgroup_mutex); |
836 | lockdep_assert_held(&css_set_rwsem); | |
837 | ||
5abb8855 | 838 | if (cset == &init_css_set) { |
3dd06ffa | 839 | res = &root->cgrp; |
7717f7ba | 840 | } else { |
69d0206c TH |
841 | struct cgrp_cset_link *link; |
842 | ||
843 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 844 | struct cgroup *c = link->cgrp; |
69d0206c | 845 | |
7717f7ba PM |
846 | if (c->root == root) { |
847 | res = c; | |
848 | break; | |
849 | } | |
850 | } | |
851 | } | |
96d365e0 | 852 | |
7717f7ba PM |
853 | BUG_ON(!res); |
854 | return res; | |
855 | } | |
856 | ||
ddbcc7e8 | 857 | /* |
ceb6a081 TH |
858 | * Return the cgroup for "task" from the given hierarchy. Must be |
859 | * called with cgroup_mutex and css_set_rwsem held. | |
860 | */ | |
861 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 862 | struct cgroup_root *root) |
ceb6a081 TH |
863 | { |
864 | /* | |
865 | * No need to lock the task - since we hold cgroup_mutex the | |
866 | * task can't change groups, so the only thing that can happen | |
867 | * is that it exits and its css is set back to init_css_set. | |
868 | */ | |
869 | return cset_cgroup_from_root(task_css_set(task), root); | |
870 | } | |
871 | ||
ddbcc7e8 | 872 | /* |
ddbcc7e8 PM |
873 | * A task must hold cgroup_mutex to modify cgroups. |
874 | * | |
875 | * Any task can increment and decrement the count field without lock. | |
876 | * So in general, code holding cgroup_mutex can't rely on the count | |
877 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 878 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
879 | * means that no tasks are currently attached, therefore there is no |
880 | * way a task attached to that cgroup can fork (the other way to | |
881 | * increment the count). So code holding cgroup_mutex can safely | |
882 | * assume that if the count is zero, it will stay zero. Similarly, if | |
883 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
884 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
885 | * needs that mutex. | |
886 | * | |
ddbcc7e8 PM |
887 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
888 | * (usually) take cgroup_mutex. These are the two most performance | |
889 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
890 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
891 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
892 | * to the release agent with the name of the cgroup (path relative to |
893 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
894 | * |
895 | * A cgroup can only be deleted if both its 'count' of using tasks | |
896 | * is zero, and its list of 'children' cgroups is empty. Since all | |
897 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 898 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 899 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 900 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
901 | * |
902 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 903 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
904 | */ |
905 | ||
628f7cd4 | 906 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); |
2bd59d48 | 907 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 908 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 909 | |
8d7e6fb0 TH |
910 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
911 | char *buf) | |
ddbcc7e8 | 912 | { |
8d7e6fb0 TH |
913 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
914 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
915 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
916 | cft->ss->name, cft->name); | |
917 | else | |
918 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
919 | return buf; | |
ddbcc7e8 PM |
920 | } |
921 | ||
f2e85d57 TH |
922 | /** |
923 | * cgroup_file_mode - deduce file mode of a control file | |
924 | * @cft: the control file in question | |
925 | * | |
926 | * returns cft->mode if ->mode is not 0 | |
927 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
928 | * returns S_IRUGO if it has only a read handler | |
929 | * returns S_IWUSR if it has only a write hander | |
930 | */ | |
931 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 932 | { |
f2e85d57 | 933 | umode_t mode = 0; |
65dff759 | 934 | |
f2e85d57 TH |
935 | if (cft->mode) |
936 | return cft->mode; | |
937 | ||
938 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) | |
939 | mode |= S_IRUGO; | |
940 | ||
941 | if (cft->write_u64 || cft->write_s64 || cft->write_string || | |
942 | cft->trigger) | |
943 | mode |= S_IWUSR; | |
944 | ||
945 | return mode; | |
65dff759 LZ |
946 | } |
947 | ||
be445626 LZ |
948 | static void cgroup_free_fn(struct work_struct *work) |
949 | { | |
ea15f8cc | 950 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); |
be445626 | 951 | |
3c9c825b | 952 | atomic_dec(&cgrp->root->nr_cgrps); |
b1a21367 | 953 | cgroup_pidlist_destroy_all(cgrp); |
be445626 | 954 | |
776f02fa TH |
955 | if (cgrp->parent) { |
956 | /* | |
957 | * We get a ref to the parent, and put the ref when this | |
958 | * cgroup is being freed, so it's guaranteed that the | |
959 | * parent won't be destroyed before its children. | |
960 | */ | |
961 | cgroup_put(cgrp->parent); | |
962 | kernfs_put(cgrp->kn); | |
963 | kfree(cgrp); | |
964 | } else { | |
965 | /* | |
3dd06ffa | 966 | * This is root cgroup's refcnt reaching zero, which |
776f02fa TH |
967 | * indicates that the root should be released. |
968 | */ | |
969 | cgroup_destroy_root(cgrp->root); | |
970 | } | |
be445626 LZ |
971 | } |
972 | ||
973 | static void cgroup_free_rcu(struct rcu_head *head) | |
974 | { | |
975 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); | |
976 | ||
ea15f8cc | 977 | INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); |
e5fca243 | 978 | queue_work(cgroup_destroy_wq, &cgrp->destroy_work); |
be445626 LZ |
979 | } |
980 | ||
59f5296b | 981 | static void cgroup_get(struct cgroup *cgrp) |
ddbcc7e8 | 982 | { |
2bd59d48 TH |
983 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
984 | WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0); | |
985 | atomic_inc(&cgrp->refcnt); | |
ddbcc7e8 PM |
986 | } |
987 | ||
59f5296b | 988 | static void cgroup_put(struct cgroup *cgrp) |
05ef1d7c | 989 | { |
2bd59d48 TH |
990 | if (!atomic_dec_and_test(&cgrp->refcnt)) |
991 | return; | |
776f02fa | 992 | if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp))) |
2bd59d48 | 993 | return; |
05ef1d7c | 994 | |
2739d3cc | 995 | /* |
2bd59d48 TH |
996 | * XXX: cgrp->id is only used to look up css's. As cgroup and |
997 | * css's lifetimes will be decoupled, it should be made | |
998 | * per-subsystem and moved to css->id so that lookups are | |
999 | * successful until the target css is released. | |
2739d3cc | 1000 | */ |
2bd59d48 TH |
1001 | mutex_lock(&cgroup_mutex); |
1002 | idr_remove(&cgrp->root->cgroup_idr, cgrp->id); | |
1003 | mutex_unlock(&cgroup_mutex); | |
1004 | cgrp->id = -1; | |
05ef1d7c | 1005 | |
2bd59d48 | 1006 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
ddbcc7e8 | 1007 | } |
05ef1d7c | 1008 | |
2739d3cc | 1009 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 1010 | { |
2bd59d48 | 1011 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 1012 | |
ace2bee8 | 1013 | lockdep_assert_held(&cgroup_tree_mutex); |
2bd59d48 | 1014 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
1015 | } |
1016 | ||
13af07df | 1017 | /** |
628f7cd4 | 1018 | * cgroup_clear_dir - remove subsys files in a cgroup directory |
8f89140a | 1019 | * @cgrp: target cgroup |
13af07df AR |
1020 | * @subsys_mask: mask of the subsystem ids whose files should be removed |
1021 | */ | |
628f7cd4 | 1022 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
05ef1d7c | 1023 | { |
13af07df | 1024 | struct cgroup_subsys *ss; |
b420ba7d | 1025 | int i; |
05ef1d7c | 1026 | |
b420ba7d | 1027 | for_each_subsys(ss, i) { |
0adb0704 | 1028 | struct cftype *cfts; |
b420ba7d TH |
1029 | |
1030 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 1031 | continue; |
0adb0704 TH |
1032 | list_for_each_entry(cfts, &ss->cfts, node) |
1033 | cgroup_addrm_files(cgrp, cfts, false); | |
13af07df | 1034 | } |
ddbcc7e8 PM |
1035 | } |
1036 | ||
3dd06ffa | 1037 | static int rebind_subsystems(struct cgroup_root *dst_root, |
5df36032 | 1038 | unsigned long ss_mask) |
ddbcc7e8 | 1039 | { |
30159ec7 | 1040 | struct cgroup_subsys *ss; |
2d8f243a | 1041 | int ssid, i, ret; |
ddbcc7e8 | 1042 | |
ace2bee8 TH |
1043 | lockdep_assert_held(&cgroup_tree_mutex); |
1044 | lockdep_assert_held(&cgroup_mutex); | |
ddbcc7e8 | 1045 | |
5df36032 TH |
1046 | for_each_subsys(ss, ssid) { |
1047 | if (!(ss_mask & (1 << ssid))) | |
1048 | continue; | |
aae8aab4 | 1049 | |
5df36032 | 1050 | /* if @ss is on the dummy_root, we can always move it */ |
3dd06ffa | 1051 | if (ss->root == &cgrp_dfl_root) |
ddbcc7e8 | 1052 | continue; |
30159ec7 | 1053 | |
5df36032 | 1054 | /* if @ss has non-root cgroups attached to it, can't move */ |
3dd06ffa | 1055 | if (!list_empty(&ss->root->cgrp.children)) |
3ed80a62 | 1056 | return -EBUSY; |
1d5be6b2 | 1057 | |
5df36032 | 1058 | /* can't move between two non-dummy roots either */ |
3dd06ffa | 1059 | if (dst_root != &cgrp_dfl_root) |
5df36032 | 1060 | return -EBUSY; |
ddbcc7e8 PM |
1061 | } |
1062 | ||
a2dd4247 TH |
1063 | ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask); |
1064 | if (ret) { | |
1065 | if (dst_root != &cgrp_dfl_root) | |
5df36032 | 1066 | return ret; |
ddbcc7e8 | 1067 | |
a2dd4247 TH |
1068 | /* |
1069 | * Rebinding back to the default root is not allowed to | |
1070 | * fail. Using both default and non-default roots should | |
1071 | * be rare. Moving subsystems back and forth even more so. | |
1072 | * Just warn about it and continue. | |
1073 | */ | |
1074 | if (cgrp_dfl_root_visible) { | |
1075 | pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n", | |
1076 | ret, ss_mask); | |
1077 | pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n"); | |
1078 | } | |
5df36032 | 1079 | } |
3126121f TH |
1080 | |
1081 | /* | |
1082 | * Nothing can fail from this point on. Remove files for the | |
1083 | * removed subsystems and rebind each subsystem. | |
1084 | */ | |
4ac06017 | 1085 | mutex_unlock(&cgroup_mutex); |
5df36032 | 1086 | for_each_subsys(ss, ssid) |
a2dd4247 | 1087 | if (ss_mask & (1 << ssid)) |
3dd06ffa | 1088 | cgroup_clear_dir(&ss->root->cgrp, 1 << ssid); |
4ac06017 | 1089 | mutex_lock(&cgroup_mutex); |
a8a648c4 | 1090 | |
5df36032 | 1091 | for_each_subsys(ss, ssid) { |
3dd06ffa | 1092 | struct cgroup_root *src_root; |
5df36032 | 1093 | struct cgroup_subsys_state *css; |
2d8f243a | 1094 | struct css_set *cset; |
a8a648c4 | 1095 | |
5df36032 TH |
1096 | if (!(ss_mask & (1 << ssid))) |
1097 | continue; | |
a8a648c4 | 1098 | |
5df36032 | 1099 | src_root = ss->root; |
3dd06ffa | 1100 | css = cgroup_css(&src_root->cgrp, ss); |
a8a648c4 | 1101 | |
3dd06ffa | 1102 | WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss)); |
73e80ed8 | 1103 | |
3dd06ffa TH |
1104 | RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL); |
1105 | rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css); | |
5df36032 | 1106 | ss->root = dst_root; |
3dd06ffa | 1107 | css->cgroup = &dst_root->cgrp; |
73e80ed8 | 1108 | |
2d8f243a TH |
1109 | down_write(&css_set_rwsem); |
1110 | hash_for_each(css_set_table, i, cset, hlist) | |
1111 | list_move_tail(&cset->e_cset_node[ss->id], | |
1112 | &dst_root->cgrp.e_csets[ss->id]); | |
1113 | up_write(&css_set_rwsem); | |
1114 | ||
f392e51c TH |
1115 | src_root->subsys_mask &= ~(1 << ssid); |
1116 | src_root->cgrp.child_subsys_mask &= ~(1 << ssid); | |
1117 | ||
1118 | dst_root->subsys_mask |= 1 << ssid; | |
1119 | dst_root->cgrp.child_subsys_mask |= 1 << ssid; | |
a8a648c4 | 1120 | |
5df36032 TH |
1121 | if (ss->bind) |
1122 | ss->bind(css); | |
ddbcc7e8 | 1123 | } |
ddbcc7e8 | 1124 | |
a2dd4247 | 1125 | kernfs_activate(dst_root->cgrp.kn); |
ddbcc7e8 PM |
1126 | return 0; |
1127 | } | |
1128 | ||
2bd59d48 TH |
1129 | static int cgroup_show_options(struct seq_file *seq, |
1130 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1131 | { |
3dd06ffa | 1132 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1133 | struct cgroup_subsys *ss; |
b85d2040 | 1134 | int ssid; |
ddbcc7e8 | 1135 | |
b85d2040 | 1136 | for_each_subsys(ss, ssid) |
f392e51c | 1137 | if (root->subsys_mask & (1 << ssid)) |
b85d2040 | 1138 | seq_printf(seq, ",%s", ss->name); |
873fe09e TH |
1139 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) |
1140 | seq_puts(seq, ",sane_behavior"); | |
93438629 | 1141 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1142 | seq_puts(seq, ",noprefix"); |
93438629 | 1143 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1144 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1145 | |
1146 | spin_lock(&release_agent_path_lock); | |
81a6a5cd PM |
1147 | if (strlen(root->release_agent_path)) |
1148 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
69e943b7 TH |
1149 | spin_unlock(&release_agent_path_lock); |
1150 | ||
3dd06ffa | 1151 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1152 | seq_puts(seq, ",clone_children"); |
c6d57f33 PM |
1153 | if (strlen(root->name)) |
1154 | seq_printf(seq, ",name=%s", root->name); | |
ddbcc7e8 PM |
1155 | return 0; |
1156 | } | |
1157 | ||
1158 | struct cgroup_sb_opts { | |
a1a71b45 | 1159 | unsigned long subsys_mask; |
ddbcc7e8 | 1160 | unsigned long flags; |
81a6a5cd | 1161 | char *release_agent; |
2260e7fc | 1162 | bool cpuset_clone_children; |
c6d57f33 | 1163 | char *name; |
2c6ab6d2 PM |
1164 | /* User explicitly requested empty subsystem */ |
1165 | bool none; | |
ddbcc7e8 PM |
1166 | }; |
1167 | ||
aae8aab4 | 1168 | /* |
9871bf95 TH |
1169 | * Convert a hierarchy specifier into a bitmask of subsystems and |
1170 | * flags. Call with cgroup_mutex held to protect the cgroup_subsys[] | |
1171 | * array. This function takes refcounts on subsystems to be used, unless it | |
1172 | * returns error, in which case no refcounts are taken. | |
aae8aab4 | 1173 | */ |
cf5d5941 | 1174 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1175 | { |
32a8cf23 DL |
1176 | char *token, *o = data; |
1177 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1178 | unsigned long mask = (unsigned long)-1; |
30159ec7 TH |
1179 | struct cgroup_subsys *ss; |
1180 | int i; | |
f9ab5b5b | 1181 | |
aae8aab4 BB |
1182 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1183 | ||
f9ab5b5b | 1184 | #ifdef CONFIG_CPUSETS |
073219e9 | 1185 | mask = ~(1UL << cpuset_cgrp_id); |
f9ab5b5b | 1186 | #endif |
ddbcc7e8 | 1187 | |
c6d57f33 | 1188 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1189 | |
1190 | while ((token = strsep(&o, ",")) != NULL) { | |
1191 | if (!*token) | |
1192 | return -EINVAL; | |
32a8cf23 | 1193 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1194 | /* Explicitly have no subsystems */ |
1195 | opts->none = true; | |
32a8cf23 DL |
1196 | continue; |
1197 | } | |
1198 | if (!strcmp(token, "all")) { | |
1199 | /* Mutually exclusive option 'all' + subsystem name */ | |
1200 | if (one_ss) | |
1201 | return -EINVAL; | |
1202 | all_ss = true; | |
1203 | continue; | |
1204 | } | |
873fe09e TH |
1205 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1206 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1207 | continue; | |
1208 | } | |
32a8cf23 | 1209 | if (!strcmp(token, "noprefix")) { |
93438629 | 1210 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1211 | continue; |
1212 | } | |
1213 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1214 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1215 | continue; |
1216 | } | |
03b1cde6 | 1217 | if (!strcmp(token, "xattr")) { |
93438629 | 1218 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1219 | continue; |
1220 | } | |
32a8cf23 | 1221 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1222 | /* Specifying two release agents is forbidden */ |
1223 | if (opts->release_agent) | |
1224 | return -EINVAL; | |
c6d57f33 | 1225 | opts->release_agent = |
e400c285 | 1226 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1227 | if (!opts->release_agent) |
1228 | return -ENOMEM; | |
32a8cf23 DL |
1229 | continue; |
1230 | } | |
1231 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1232 | const char *name = token + 5; |
1233 | /* Can't specify an empty name */ | |
1234 | if (!strlen(name)) | |
1235 | return -EINVAL; | |
1236 | /* Must match [\w.-]+ */ | |
1237 | for (i = 0; i < strlen(name); i++) { | |
1238 | char c = name[i]; | |
1239 | if (isalnum(c)) | |
1240 | continue; | |
1241 | if ((c == '.') || (c == '-') || (c == '_')) | |
1242 | continue; | |
1243 | return -EINVAL; | |
1244 | } | |
1245 | /* Specifying two names is forbidden */ | |
1246 | if (opts->name) | |
1247 | return -EINVAL; | |
1248 | opts->name = kstrndup(name, | |
e400c285 | 1249 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1250 | GFP_KERNEL); |
1251 | if (!opts->name) | |
1252 | return -ENOMEM; | |
32a8cf23 DL |
1253 | |
1254 | continue; | |
1255 | } | |
1256 | ||
30159ec7 | 1257 | for_each_subsys(ss, i) { |
32a8cf23 DL |
1258 | if (strcmp(token, ss->name)) |
1259 | continue; | |
1260 | if (ss->disabled) | |
1261 | continue; | |
1262 | ||
1263 | /* Mutually exclusive option 'all' + subsystem name */ | |
1264 | if (all_ss) | |
1265 | return -EINVAL; | |
a1a71b45 | 1266 | set_bit(i, &opts->subsys_mask); |
32a8cf23 DL |
1267 | one_ss = true; |
1268 | ||
1269 | break; | |
1270 | } | |
1271 | if (i == CGROUP_SUBSYS_COUNT) | |
1272 | return -ENOENT; | |
1273 | } | |
1274 | ||
2c6ab6d2 PM |
1275 | /* Consistency checks */ |
1276 | ||
873fe09e TH |
1277 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1278 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); | |
1279 | ||
d3ba07c3 TH |
1280 | if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) || |
1281 | opts->cpuset_clone_children || opts->release_agent || | |
1282 | opts->name) { | |
1283 | pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n"); | |
873fe09e TH |
1284 | return -EINVAL; |
1285 | } | |
a2dd4247 TH |
1286 | } else { |
1287 | /* | |
1288 | * If the 'all' option was specified select all the | |
1289 | * subsystems, otherwise if 'none', 'name=' and a subsystem | |
1290 | * name options were not specified, let's default to 'all' | |
1291 | */ | |
1292 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1293 | for_each_subsys(ss, i) | |
1294 | if (!ss->disabled) | |
1295 | set_bit(i, &opts->subsys_mask); | |
873fe09e | 1296 | |
a2dd4247 TH |
1297 | /* |
1298 | * We either have to specify by name or by subsystems. (So | |
1299 | * all empty hierarchies must have a name). | |
1300 | */ | |
1301 | if (!opts->subsys_mask && !opts->name) | |
873fe09e | 1302 | return -EINVAL; |
873fe09e TH |
1303 | } |
1304 | ||
f9ab5b5b LZ |
1305 | /* |
1306 | * Option noprefix was introduced just for backward compatibility | |
1307 | * with the old cpuset, so we allow noprefix only if mounting just | |
1308 | * the cpuset subsystem. | |
1309 | */ | |
93438629 | 1310 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1311 | return -EINVAL; |
1312 | ||
2c6ab6d2 PM |
1313 | |
1314 | /* Can't specify "none" and some subsystems */ | |
a1a71b45 | 1315 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1316 | return -EINVAL; |
1317 | ||
ddbcc7e8 PM |
1318 | return 0; |
1319 | } | |
1320 | ||
2bd59d48 | 1321 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1322 | { |
1323 | int ret = 0; | |
3dd06ffa | 1324 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1325 | struct cgroup_sb_opts opts; |
a1a71b45 | 1326 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1327 | |
873fe09e TH |
1328 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1329 | pr_err("cgroup: sane_behavior: remount is not allowed\n"); | |
1330 | return -EINVAL; | |
1331 | } | |
1332 | ||
ace2bee8 | 1333 | mutex_lock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
1334 | mutex_lock(&cgroup_mutex); |
1335 | ||
1336 | /* See what subsystems are wanted */ | |
1337 | ret = parse_cgroupfs_options(data, &opts); | |
1338 | if (ret) | |
1339 | goto out_unlock; | |
1340 | ||
f392e51c | 1341 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
8b5a5a9d TH |
1342 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", |
1343 | task_tgid_nr(current), current->comm); | |
1344 | ||
f392e51c TH |
1345 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1346 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1347 | |
cf5d5941 | 1348 | /* Don't allow flags or name to change at remount */ |
0ce6cba3 | 1349 | if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) || |
cf5d5941 | 1350 | (opts.name && strcmp(opts.name, root->name))) { |
0ce6cba3 TH |
1351 | pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n", |
1352 | opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "", | |
1353 | root->flags & CGRP_ROOT_OPTION_MASK, root->name); | |
c6d57f33 PM |
1354 | ret = -EINVAL; |
1355 | goto out_unlock; | |
1356 | } | |
1357 | ||
f172e67c | 1358 | /* remounting is not allowed for populated hierarchies */ |
3dd06ffa | 1359 | if (!list_empty(&root->cgrp.children)) { |
f172e67c | 1360 | ret = -EBUSY; |
0670e08b | 1361 | goto out_unlock; |
cf5d5941 | 1362 | } |
ddbcc7e8 | 1363 | |
5df36032 | 1364 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1365 | if (ret) |
0670e08b | 1366 | goto out_unlock; |
ddbcc7e8 | 1367 | |
3dd06ffa | 1368 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1369 | |
69e943b7 TH |
1370 | if (opts.release_agent) { |
1371 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1372 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1373 | spin_unlock(&release_agent_path_lock); |
1374 | } | |
ddbcc7e8 | 1375 | out_unlock: |
66bdc9cf | 1376 | kfree(opts.release_agent); |
c6d57f33 | 1377 | kfree(opts.name); |
ddbcc7e8 | 1378 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 1379 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
1380 | return ret; |
1381 | } | |
1382 | ||
afeb0f9f TH |
1383 | /* |
1384 | * To reduce the fork() overhead for systems that are not actually using | |
1385 | * their cgroups capability, we don't maintain the lists running through | |
1386 | * each css_set to its tasks until we see the list actually used - in other | |
1387 | * words after the first mount. | |
1388 | */ | |
1389 | static bool use_task_css_set_links __read_mostly; | |
1390 | ||
1391 | static void cgroup_enable_task_cg_lists(void) | |
1392 | { | |
1393 | struct task_struct *p, *g; | |
1394 | ||
96d365e0 | 1395 | down_write(&css_set_rwsem); |
afeb0f9f TH |
1396 | |
1397 | if (use_task_css_set_links) | |
1398 | goto out_unlock; | |
1399 | ||
1400 | use_task_css_set_links = true; | |
1401 | ||
1402 | /* | |
1403 | * We need tasklist_lock because RCU is not safe against | |
1404 | * while_each_thread(). Besides, a forking task that has passed | |
1405 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1406 | * is not guaranteed to have its child immediately visible in the | |
1407 | * tasklist if we walk through it with RCU. | |
1408 | */ | |
1409 | read_lock(&tasklist_lock); | |
1410 | do_each_thread(g, p) { | |
afeb0f9f TH |
1411 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1412 | task_css_set(p) != &init_css_set); | |
1413 | ||
1414 | /* | |
1415 | * We should check if the process is exiting, otherwise | |
1416 | * it will race with cgroup_exit() in that the list | |
1417 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1418 | * Do it while holding siglock so that we don't end up |
1419 | * racing against cgroup_exit(). | |
afeb0f9f | 1420 | */ |
f153ad11 | 1421 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1422 | if (!(p->flags & PF_EXITING)) { |
1423 | struct css_set *cset = task_css_set(p); | |
1424 | ||
1425 | list_add(&p->cg_list, &cset->tasks); | |
1426 | get_css_set(cset); | |
1427 | } | |
f153ad11 | 1428 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1429 | } while_each_thread(g, p); |
1430 | read_unlock(&tasklist_lock); | |
1431 | out_unlock: | |
96d365e0 | 1432 | up_write(&css_set_rwsem); |
afeb0f9f | 1433 | } |
ddbcc7e8 | 1434 | |
cc31edce PM |
1435 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1436 | { | |
2d8f243a TH |
1437 | struct cgroup_subsys *ss; |
1438 | int ssid; | |
1439 | ||
2bd59d48 | 1440 | atomic_set(&cgrp->refcnt, 1); |
cc31edce PM |
1441 | INIT_LIST_HEAD(&cgrp->sibling); |
1442 | INIT_LIST_HEAD(&cgrp->children); | |
69d0206c | 1443 | INIT_LIST_HEAD(&cgrp->cset_links); |
cc31edce | 1444 | INIT_LIST_HEAD(&cgrp->release_list); |
72a8cb30 BB |
1445 | INIT_LIST_HEAD(&cgrp->pidlists); |
1446 | mutex_init(&cgrp->pidlist_mutex); | |
67f4c36f | 1447 | cgrp->dummy_css.cgroup = cgrp; |
2d8f243a TH |
1448 | |
1449 | for_each_subsys(ss, ssid) | |
1450 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]); | |
cc31edce | 1451 | } |
c6d57f33 | 1452 | |
3dd06ffa | 1453 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1454 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1455 | { |
3dd06ffa | 1456 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1457 | |
ddbcc7e8 | 1458 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1459 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1460 | cgrp->root = root; |
cc31edce | 1461 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1462 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1463 | |
c6d57f33 PM |
1464 | root->flags = opts->flags; |
1465 | if (opts->release_agent) | |
1466 | strcpy(root->release_agent_path, opts->release_agent); | |
1467 | if (opts->name) | |
1468 | strcpy(root->name, opts->name); | |
2260e7fc | 1469 | if (opts->cpuset_clone_children) |
3dd06ffa | 1470 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1471 | } |
1472 | ||
3dd06ffa | 1473 | static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) |
2c6ab6d2 | 1474 | { |
d427dfeb | 1475 | LIST_HEAD(tmp_links); |
3dd06ffa | 1476 | struct cgroup *root_cgrp = &root->cgrp; |
d427dfeb | 1477 | struct css_set *cset; |
d427dfeb | 1478 | int i, ret; |
2c6ab6d2 | 1479 | |
d427dfeb TH |
1480 | lockdep_assert_held(&cgroup_tree_mutex); |
1481 | lockdep_assert_held(&cgroup_mutex); | |
c6d57f33 | 1482 | |
d427dfeb TH |
1483 | ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL); |
1484 | if (ret < 0) | |
2bd59d48 | 1485 | goto out; |
d427dfeb | 1486 | root_cgrp->id = ret; |
c6d57f33 | 1487 | |
d427dfeb | 1488 | /* |
96d365e0 | 1489 | * We're accessing css_set_count without locking css_set_rwsem here, |
d427dfeb TH |
1490 | * but that's OK - it can only be increased by someone holding |
1491 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1492 | * have some link structures left over | |
1493 | */ | |
1494 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1495 | if (ret) | |
2bd59d48 | 1496 | goto out; |
ddbcc7e8 | 1497 | |
985ed670 | 1498 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1499 | if (ret) |
2bd59d48 | 1500 | goto out; |
ddbcc7e8 | 1501 | |
2bd59d48 TH |
1502 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1503 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1504 | root_cgrp); | |
1505 | if (IS_ERR(root->kf_root)) { | |
1506 | ret = PTR_ERR(root->kf_root); | |
1507 | goto exit_root_id; | |
1508 | } | |
1509 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1510 | |
d427dfeb TH |
1511 | ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true); |
1512 | if (ret) | |
2bd59d48 | 1513 | goto destroy_root; |
ddbcc7e8 | 1514 | |
5df36032 | 1515 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1516 | if (ret) |
2bd59d48 | 1517 | goto destroy_root; |
ddbcc7e8 | 1518 | |
d427dfeb TH |
1519 | /* |
1520 | * There must be no failure case after here, since rebinding takes | |
1521 | * care of subsystems' refcounts, which are explicitly dropped in | |
1522 | * the failure exit path. | |
1523 | */ | |
1524 | list_add(&root->root_list, &cgroup_roots); | |
1525 | cgroup_root_count++; | |
0df6a63f | 1526 | |
d427dfeb | 1527 | /* |
3dd06ffa | 1528 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1529 | * objects. |
1530 | */ | |
96d365e0 | 1531 | down_write(&css_set_rwsem); |
d427dfeb TH |
1532 | hash_for_each(css_set_table, i, cset, hlist) |
1533 | link_css_set(&tmp_links, cset, root_cgrp); | |
96d365e0 | 1534 | up_write(&css_set_rwsem); |
ddbcc7e8 | 1535 | |
d427dfeb | 1536 | BUG_ON(!list_empty(&root_cgrp->children)); |
3c9c825b | 1537 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1538 | |
2bd59d48 | 1539 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1540 | ret = 0; |
2bd59d48 | 1541 | goto out; |
d427dfeb | 1542 | |
2bd59d48 TH |
1543 | destroy_root: |
1544 | kernfs_destroy_root(root->kf_root); | |
1545 | root->kf_root = NULL; | |
1546 | exit_root_id: | |
d427dfeb | 1547 | cgroup_exit_root_id(root); |
2bd59d48 | 1548 | out: |
d427dfeb TH |
1549 | free_cgrp_cset_links(&tmp_links); |
1550 | return ret; | |
ddbcc7e8 PM |
1551 | } |
1552 | ||
f7e83571 | 1553 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1554 | int flags, const char *unused_dev_name, |
f7e83571 | 1555 | void *data) |
ddbcc7e8 | 1556 | { |
3dd06ffa | 1557 | struct cgroup_root *root; |
ddbcc7e8 | 1558 | struct cgroup_sb_opts opts; |
2bd59d48 | 1559 | struct dentry *dentry; |
8e30e2b8 | 1560 | int ret; |
c6b3d5bc | 1561 | bool new_sb; |
ddbcc7e8 | 1562 | |
56fde9e0 TH |
1563 | /* |
1564 | * The first time anyone tries to mount a cgroup, enable the list | |
1565 | * linking each css_set to its tasks and fix up all existing tasks. | |
1566 | */ | |
1567 | if (!use_task_css_set_links) | |
1568 | cgroup_enable_task_cg_lists(); | |
e37a06f1 | 1569 | |
8e30e2b8 | 1570 | mutex_lock(&cgroup_tree_mutex); |
aae8aab4 | 1571 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
1572 | |
1573 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 1574 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 1575 | if (ret) |
8e30e2b8 | 1576 | goto out_unlock; |
e37a06f1 | 1577 | retry: |
2bd59d48 | 1578 | /* look for a matching existing root */ |
a2dd4247 TH |
1579 | if (!opts.subsys_mask && !opts.none && !opts.name) { |
1580 | cgrp_dfl_root_visible = true; | |
1581 | root = &cgrp_dfl_root; | |
1582 | cgroup_get(&root->cgrp); | |
1583 | ret = 0; | |
1584 | goto out_unlock; | |
ddbcc7e8 PM |
1585 | } |
1586 | ||
985ed670 | 1587 | for_each_root(root) { |
2bd59d48 | 1588 | bool name_match = false; |
3126121f | 1589 | |
3dd06ffa | 1590 | if (root == &cgrp_dfl_root) |
985ed670 | 1591 | continue; |
3126121f | 1592 | |
cf5d5941 | 1593 | /* |
2bd59d48 TH |
1594 | * If we asked for a name then it must match. Also, if |
1595 | * name matches but sybsys_mask doesn't, we should fail. | |
1596 | * Remember whether name matched. | |
cf5d5941 | 1597 | */ |
2bd59d48 TH |
1598 | if (opts.name) { |
1599 | if (strcmp(opts.name, root->name)) | |
1600 | continue; | |
1601 | name_match = true; | |
1602 | } | |
ddbcc7e8 | 1603 | |
c6d57f33 | 1604 | /* |
2bd59d48 TH |
1605 | * If we asked for subsystems (or explicitly for no |
1606 | * subsystems) then they must match. | |
c6d57f33 | 1607 | */ |
2bd59d48 | 1608 | if ((opts.subsys_mask || opts.none) && |
f392e51c | 1609 | (opts.subsys_mask != root->subsys_mask)) { |
2bd59d48 TH |
1610 | if (!name_match) |
1611 | continue; | |
1612 | ret = -EBUSY; | |
1613 | goto out_unlock; | |
1614 | } | |
873fe09e | 1615 | |
c7ba8287 | 1616 | if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) { |
2a0ff3fb JL |
1617 | if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { |
1618 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); | |
1619 | ret = -EINVAL; | |
8e30e2b8 | 1620 | goto out_unlock; |
2a0ff3fb JL |
1621 | } else { |
1622 | pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); | |
1623 | } | |
873fe09e | 1624 | } |
ddbcc7e8 | 1625 | |
776f02fa | 1626 | /* |
3dd06ffa | 1627 | * A root's lifetime is governed by its root cgroup. Zero |
776f02fa TH |
1628 | * ref indicate that the root is being destroyed. Wait for |
1629 | * destruction to complete so that the subsystems are free. | |
1630 | * We can use wait_queue for the wait but this path is | |
1631 | * super cold. Let's just sleep for a bit and retry. | |
1632 | */ | |
3dd06ffa | 1633 | if (!atomic_inc_not_zero(&root->cgrp.refcnt)) { |
776f02fa TH |
1634 | mutex_unlock(&cgroup_mutex); |
1635 | mutex_unlock(&cgroup_tree_mutex); | |
1636 | msleep(10); | |
e37a06f1 LZ |
1637 | mutex_lock(&cgroup_tree_mutex); |
1638 | mutex_lock(&cgroup_mutex); | |
776f02fa TH |
1639 | goto retry; |
1640 | } | |
ddbcc7e8 | 1641 | |
776f02fa | 1642 | ret = 0; |
2bd59d48 | 1643 | goto out_unlock; |
ddbcc7e8 | 1644 | } |
ddbcc7e8 | 1645 | |
817929ec | 1646 | /* |
172a2c06 TH |
1647 | * No such thing, create a new one. name= matching without subsys |
1648 | * specification is allowed for already existing hierarchies but we | |
1649 | * can't create new one without subsys specification. | |
817929ec | 1650 | */ |
172a2c06 TH |
1651 | if (!opts.subsys_mask && !opts.none) { |
1652 | ret = -EINVAL; | |
1653 | goto out_unlock; | |
817929ec | 1654 | } |
817929ec | 1655 | |
172a2c06 TH |
1656 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
1657 | if (!root) { | |
1658 | ret = -ENOMEM; | |
2bd59d48 | 1659 | goto out_unlock; |
839ec545 | 1660 | } |
e5f6a860 | 1661 | |
172a2c06 TH |
1662 | init_cgroup_root(root, &opts); |
1663 | ||
35585573 | 1664 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
1665 | if (ret) |
1666 | cgroup_free_root(root); | |
fa3ca07e | 1667 | |
8e30e2b8 | 1668 | out_unlock: |
ddbcc7e8 | 1669 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 1670 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 | 1671 | |
c6d57f33 PM |
1672 | kfree(opts.release_agent); |
1673 | kfree(opts.name); | |
03b1cde6 | 1674 | |
2bd59d48 | 1675 | if (ret) |
8e30e2b8 | 1676 | return ERR_PTR(ret); |
2bd59d48 | 1677 | |
c6b3d5bc LZ |
1678 | dentry = kernfs_mount(fs_type, flags, root->kf_root, &new_sb); |
1679 | if (IS_ERR(dentry) || !new_sb) | |
3dd06ffa | 1680 | cgroup_put(&root->cgrp); |
2bd59d48 TH |
1681 | return dentry; |
1682 | } | |
1683 | ||
1684 | static void cgroup_kill_sb(struct super_block *sb) | |
1685 | { | |
1686 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 1687 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 1688 | |
3dd06ffa | 1689 | cgroup_put(&root->cgrp); |
2bd59d48 | 1690 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
1691 | } |
1692 | ||
1693 | static struct file_system_type cgroup_fs_type = { | |
1694 | .name = "cgroup", | |
f7e83571 | 1695 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1696 | .kill_sb = cgroup_kill_sb, |
1697 | }; | |
1698 | ||
676db4af GKH |
1699 | static struct kobject *cgroup_kobj; |
1700 | ||
857a2beb | 1701 | /** |
913ffdb5 | 1702 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 1703 | * @task: target task |
857a2beb TH |
1704 | * @buf: the buffer to write the path into |
1705 | * @buflen: the length of the buffer | |
1706 | * | |
913ffdb5 TH |
1707 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
1708 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
1709 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
1710 | * cgroup controller callbacks. | |
1711 | * | |
e61734c5 | 1712 | * Return value is the same as kernfs_path(). |
857a2beb | 1713 | */ |
e61734c5 | 1714 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 1715 | { |
3dd06ffa | 1716 | struct cgroup_root *root; |
913ffdb5 | 1717 | struct cgroup *cgrp; |
e61734c5 TH |
1718 | int hierarchy_id = 1; |
1719 | char *path = NULL; | |
857a2beb TH |
1720 | |
1721 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 1722 | down_read(&css_set_rwsem); |
857a2beb | 1723 | |
913ffdb5 TH |
1724 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
1725 | ||
857a2beb TH |
1726 | if (root) { |
1727 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 1728 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
1729 | } else { |
1730 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
1731 | if (strlcpy(buf, "/", buflen) < buflen) |
1732 | path = buf; | |
857a2beb TH |
1733 | } |
1734 | ||
96d365e0 | 1735 | up_read(&css_set_rwsem); |
857a2beb | 1736 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 1737 | return path; |
857a2beb | 1738 | } |
913ffdb5 | 1739 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 1740 | |
b3dc094e | 1741 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 1742 | struct cgroup_taskset { |
b3dc094e TH |
1743 | /* the src and dst cset list running through cset->mg_node */ |
1744 | struct list_head src_csets; | |
1745 | struct list_head dst_csets; | |
1746 | ||
1747 | /* | |
1748 | * Fields for cgroup_taskset_*() iteration. | |
1749 | * | |
1750 | * Before migration is committed, the target migration tasks are on | |
1751 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
1752 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
1753 | * or ->dst_csets depending on whether migration is committed. | |
1754 | * | |
1755 | * ->cur_csets and ->cur_task point to the current task position | |
1756 | * during iteration. | |
1757 | */ | |
1758 | struct list_head *csets; | |
1759 | struct css_set *cur_cset; | |
1760 | struct task_struct *cur_task; | |
2f7ee569 TH |
1761 | }; |
1762 | ||
1763 | /** | |
1764 | * cgroup_taskset_first - reset taskset and return the first task | |
1765 | * @tset: taskset of interest | |
1766 | * | |
1767 | * @tset iteration is initialized and the first task is returned. | |
1768 | */ | |
1769 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1770 | { | |
b3dc094e TH |
1771 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
1772 | tset->cur_task = NULL; | |
1773 | ||
1774 | return cgroup_taskset_next(tset); | |
2f7ee569 | 1775 | } |
2f7ee569 TH |
1776 | |
1777 | /** | |
1778 | * cgroup_taskset_next - iterate to the next task in taskset | |
1779 | * @tset: taskset of interest | |
1780 | * | |
1781 | * Return the next task in @tset. Iteration must have been initialized | |
1782 | * with cgroup_taskset_first(). | |
1783 | */ | |
1784 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1785 | { | |
b3dc094e TH |
1786 | struct css_set *cset = tset->cur_cset; |
1787 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 1788 | |
b3dc094e TH |
1789 | while (&cset->mg_node != tset->csets) { |
1790 | if (!task) | |
1791 | task = list_first_entry(&cset->mg_tasks, | |
1792 | struct task_struct, cg_list); | |
1793 | else | |
1794 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 1795 | |
b3dc094e TH |
1796 | if (&task->cg_list != &cset->mg_tasks) { |
1797 | tset->cur_cset = cset; | |
1798 | tset->cur_task = task; | |
1799 | return task; | |
1800 | } | |
2f7ee569 | 1801 | |
b3dc094e TH |
1802 | cset = list_next_entry(cset, mg_node); |
1803 | task = NULL; | |
1804 | } | |
2f7ee569 | 1805 | |
b3dc094e | 1806 | return NULL; |
2f7ee569 | 1807 | } |
2f7ee569 | 1808 | |
cb0f1fe9 | 1809 | /** |
74a1166d | 1810 | * cgroup_task_migrate - move a task from one cgroup to another. |
cb0f1fe9 TH |
1811 | * @old_cgrp; the cgroup @tsk is being migrated from |
1812 | * @tsk: the task being migrated | |
1813 | * @new_cset: the new css_set @tsk is being attached to | |
74a1166d | 1814 | * |
cb0f1fe9 | 1815 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. |
74a1166d | 1816 | */ |
5abb8855 TH |
1817 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
1818 | struct task_struct *tsk, | |
1819 | struct css_set *new_cset) | |
74a1166d | 1820 | { |
5abb8855 | 1821 | struct css_set *old_cset; |
74a1166d | 1822 | |
cb0f1fe9 TH |
1823 | lockdep_assert_held(&cgroup_mutex); |
1824 | lockdep_assert_held(&css_set_rwsem); | |
1825 | ||
74a1166d | 1826 | /* |
026085ef MSB |
1827 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1828 | * setting such that we can't race against cgroup_exit() changing the | |
1829 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1830 | */ |
c84cdf75 | 1831 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 1832 | old_cset = task_css_set(tsk); |
74a1166d | 1833 | |
b3dc094e | 1834 | get_css_set(new_cset); |
5abb8855 | 1835 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d | 1836 | |
1b9aba49 TH |
1837 | /* |
1838 | * Use move_tail so that cgroup_taskset_first() still returns the | |
1839 | * leader after migration. This works because cgroup_migrate() | |
1840 | * ensures that the dst_cset of the leader is the first on the | |
1841 | * tset's dst_csets list. | |
1842 | */ | |
1843 | list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); | |
74a1166d BB |
1844 | |
1845 | /* | |
5abb8855 TH |
1846 | * We just gained a reference on old_cset by taking it from the |
1847 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
1848 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 1849 | */ |
5abb8855 | 1850 | set_bit(CGRP_RELEASABLE, &old_cgrp->flags); |
cb0f1fe9 | 1851 | put_css_set_locked(old_cset, false); |
74a1166d BB |
1852 | } |
1853 | ||
a043e3b2 | 1854 | /** |
1958d2d5 TH |
1855 | * cgroup_migrate_finish - cleanup after attach |
1856 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 1857 | * |
1958d2d5 TH |
1858 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
1859 | * those functions for details. | |
74a1166d | 1860 | */ |
1958d2d5 | 1861 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 1862 | { |
1958d2d5 | 1863 | struct css_set *cset, *tmp_cset; |
74a1166d | 1864 | |
1958d2d5 TH |
1865 | lockdep_assert_held(&cgroup_mutex); |
1866 | ||
1867 | down_write(&css_set_rwsem); | |
1868 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { | |
1869 | cset->mg_src_cgrp = NULL; | |
1870 | cset->mg_dst_cset = NULL; | |
1871 | list_del_init(&cset->mg_preload_node); | |
1872 | put_css_set_locked(cset, false); | |
1873 | } | |
1874 | up_write(&css_set_rwsem); | |
1875 | } | |
1876 | ||
1877 | /** | |
1878 | * cgroup_migrate_add_src - add a migration source css_set | |
1879 | * @src_cset: the source css_set to add | |
1880 | * @dst_cgrp: the destination cgroup | |
1881 | * @preloaded_csets: list of preloaded css_sets | |
1882 | * | |
1883 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
1884 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
1885 | * up by cgroup_migrate_finish(). | |
1886 | * | |
1887 | * This function may be called without holding threadgroup_lock even if the | |
1888 | * target is a process. Threads may be created and destroyed but as long | |
1889 | * as cgroup_mutex is not dropped, no new css_set can be put into play and | |
1890 | * the preloaded css_sets are guaranteed to cover all migrations. | |
1891 | */ | |
1892 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
1893 | struct cgroup *dst_cgrp, | |
1894 | struct list_head *preloaded_csets) | |
1895 | { | |
1896 | struct cgroup *src_cgrp; | |
1897 | ||
1898 | lockdep_assert_held(&cgroup_mutex); | |
1899 | lockdep_assert_held(&css_set_rwsem); | |
1900 | ||
1901 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
1902 | ||
1903 | /* nothing to do if this cset already belongs to the cgroup */ | |
1904 | if (src_cgrp == dst_cgrp) | |
1905 | return; | |
1906 | ||
1907 | if (!list_empty(&src_cset->mg_preload_node)) | |
1908 | return; | |
1909 | ||
1910 | WARN_ON(src_cset->mg_src_cgrp); | |
1911 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
1912 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
1913 | ||
1914 | src_cset->mg_src_cgrp = src_cgrp; | |
1915 | get_css_set(src_cset); | |
1916 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
1917 | } | |
1918 | ||
1919 | /** | |
1920 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
1921 | * @dst_cgrp: the destination cgroup | |
1922 | * @preloaded_csets: list of preloaded source css_sets | |
1923 | * | |
1924 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
1925 | * have been preloaded to @preloaded_csets. This function looks up and | |
1926 | * pins all destination css_sets, links each to its source, and put them on | |
1927 | * @preloaded_csets. | |
1928 | * | |
1929 | * This function must be called after cgroup_migrate_add_src() has been | |
1930 | * called on each migration source css_set. After migration is performed | |
1931 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
1932 | * @preloaded_csets. | |
1933 | */ | |
1934 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
1935 | struct list_head *preloaded_csets) | |
1936 | { | |
1937 | LIST_HEAD(csets); | |
1938 | struct css_set *src_cset; | |
1939 | ||
1940 | lockdep_assert_held(&cgroup_mutex); | |
1941 | ||
1942 | /* look up the dst cset for each src cset and link it to src */ | |
1943 | list_for_each_entry(src_cset, preloaded_csets, mg_preload_node) { | |
1944 | struct css_set *dst_cset; | |
1945 | ||
1946 | dst_cset = find_css_set(src_cset, dst_cgrp); | |
1947 | if (!dst_cset) | |
1948 | goto err; | |
1949 | ||
1950 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
1951 | src_cset->mg_dst_cset = dst_cset; | |
1952 | ||
1953 | if (list_empty(&dst_cset->mg_preload_node)) | |
1954 | list_add(&dst_cset->mg_preload_node, &csets); | |
1955 | else | |
1956 | put_css_set(dst_cset, false); | |
1957 | } | |
1958 | ||
1959 | list_splice(&csets, preloaded_csets); | |
1960 | return 0; | |
1961 | err: | |
1962 | cgroup_migrate_finish(&csets); | |
1963 | return -ENOMEM; | |
1964 | } | |
1965 | ||
1966 | /** | |
1967 | * cgroup_migrate - migrate a process or task to a cgroup | |
1968 | * @cgrp: the destination cgroup | |
1969 | * @leader: the leader of the process or the task to migrate | |
1970 | * @threadgroup: whether @leader points to the whole process or a single task | |
1971 | * | |
1972 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1973 | * process, the caller must be holding threadgroup_lock of @leader. The | |
1974 | * caller is also responsible for invoking cgroup_migrate_add_src() and | |
1975 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
1976 | * function and following up with cgroup_migrate_finish(). | |
1977 | * | |
1978 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
1979 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
1980 | * failure, when migrating multiple targets, the success or failure can be | |
1981 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
1982 | * actually starting migrating. | |
1983 | */ | |
1984 | static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader, | |
1985 | bool threadgroup) | |
74a1166d | 1986 | { |
b3dc094e TH |
1987 | struct cgroup_taskset tset = { |
1988 | .src_csets = LIST_HEAD_INIT(tset.src_csets), | |
1989 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), | |
1990 | .csets = &tset.src_csets, | |
1991 | }; | |
1c6727af | 1992 | struct cgroup_subsys_state *css, *failed_css = NULL; |
b3dc094e TH |
1993 | struct css_set *cset, *tmp_cset; |
1994 | struct task_struct *task, *tmp_task; | |
1995 | int i, ret; | |
74a1166d | 1996 | |
fb5d2b4c MSB |
1997 | /* |
1998 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
1999 | * already PF_EXITING could be freed from underneath us unless we | |
2000 | * take an rcu_read_lock. | |
2001 | */ | |
b3dc094e | 2002 | down_write(&css_set_rwsem); |
fb5d2b4c | 2003 | rcu_read_lock(); |
9db8de37 | 2004 | task = leader; |
74a1166d | 2005 | do { |
9db8de37 TH |
2006 | /* @task either already exited or can't exit until the end */ |
2007 | if (task->flags & PF_EXITING) | |
ea84753c | 2008 | goto next; |
134d3373 | 2009 | |
eaf797ab TH |
2010 | /* leave @task alone if post_fork() hasn't linked it yet */ |
2011 | if (list_empty(&task->cg_list)) | |
ea84753c | 2012 | goto next; |
cd3d0952 | 2013 | |
b3dc094e | 2014 | cset = task_css_set(task); |
1958d2d5 | 2015 | if (!cset->mg_src_cgrp) |
ea84753c | 2016 | goto next; |
b3dc094e | 2017 | |
61d1d219 | 2018 | /* |
1b9aba49 TH |
2019 | * cgroup_taskset_first() must always return the leader. |
2020 | * Take care to avoid disturbing the ordering. | |
61d1d219 | 2021 | */ |
1b9aba49 TH |
2022 | list_move_tail(&task->cg_list, &cset->mg_tasks); |
2023 | if (list_empty(&cset->mg_node)) | |
2024 | list_add_tail(&cset->mg_node, &tset.src_csets); | |
2025 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
2026 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
2027 | &tset.dst_csets); | |
ea84753c | 2028 | next: |
081aa458 LZ |
2029 | if (!threadgroup) |
2030 | break; | |
9db8de37 | 2031 | } while_each_thread(leader, task); |
fb5d2b4c | 2032 | rcu_read_unlock(); |
b3dc094e | 2033 | up_write(&css_set_rwsem); |
74a1166d | 2034 | |
134d3373 | 2035 | /* methods shouldn't be called if no task is actually migrating */ |
b3dc094e TH |
2036 | if (list_empty(&tset.src_csets)) |
2037 | return 0; | |
134d3373 | 2038 | |
1958d2d5 | 2039 | /* check that we can legitimately attach to the cgroup */ |
aec3dfcb | 2040 | for_each_e_css(css, i, cgrp) { |
1c6727af | 2041 | if (css->ss->can_attach) { |
9db8de37 TH |
2042 | ret = css->ss->can_attach(css, &tset); |
2043 | if (ret) { | |
1c6727af | 2044 | failed_css = css; |
74a1166d BB |
2045 | goto out_cancel_attach; |
2046 | } | |
2047 | } | |
74a1166d BB |
2048 | } |
2049 | ||
2050 | /* | |
1958d2d5 TH |
2051 | * Now that we're guaranteed success, proceed to move all tasks to |
2052 | * the new cgroup. There are no failure cases after here, so this | |
2053 | * is the commit point. | |
74a1166d | 2054 | */ |
cb0f1fe9 | 2055 | down_write(&css_set_rwsem); |
b3dc094e TH |
2056 | list_for_each_entry(cset, &tset.src_csets, mg_node) { |
2057 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) | |
2058 | cgroup_task_migrate(cset->mg_src_cgrp, task, | |
2059 | cset->mg_dst_cset); | |
74a1166d | 2060 | } |
cb0f1fe9 | 2061 | up_write(&css_set_rwsem); |
74a1166d BB |
2062 | |
2063 | /* | |
1958d2d5 TH |
2064 | * Migration is committed, all target tasks are now on dst_csets. |
2065 | * Nothing is sensitive to fork() after this point. Notify | |
2066 | * controllers that migration is complete. | |
74a1166d | 2067 | */ |
1958d2d5 | 2068 | tset.csets = &tset.dst_csets; |
74a1166d | 2069 | |
aec3dfcb | 2070 | for_each_e_css(css, i, cgrp) |
1c6727af TH |
2071 | if (css->ss->attach) |
2072 | css->ss->attach(css, &tset); | |
74a1166d | 2073 | |
9db8de37 | 2074 | ret = 0; |
b3dc094e TH |
2075 | goto out_release_tset; |
2076 | ||
74a1166d | 2077 | out_cancel_attach: |
aec3dfcb | 2078 | for_each_e_css(css, i, cgrp) { |
b3dc094e TH |
2079 | if (css == failed_css) |
2080 | break; | |
2081 | if (css->ss->cancel_attach) | |
2082 | css->ss->cancel_attach(css, &tset); | |
74a1166d | 2083 | } |
b3dc094e TH |
2084 | out_release_tset: |
2085 | down_write(&css_set_rwsem); | |
2086 | list_splice_init(&tset.dst_csets, &tset.src_csets); | |
2087 | list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) { | |
1b9aba49 | 2088 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
b3dc094e | 2089 | list_del_init(&cset->mg_node); |
b3dc094e TH |
2090 | } |
2091 | up_write(&css_set_rwsem); | |
9db8de37 | 2092 | return ret; |
74a1166d BB |
2093 | } |
2094 | ||
1958d2d5 TH |
2095 | /** |
2096 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2097 | * @dst_cgrp: the cgroup to attach to | |
2098 | * @leader: the task or the leader of the threadgroup to be attached | |
2099 | * @threadgroup: attach the whole threadgroup? | |
2100 | * | |
0e1d768f | 2101 | * Call holding cgroup_mutex and threadgroup_lock of @leader. |
1958d2d5 TH |
2102 | */ |
2103 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2104 | struct task_struct *leader, bool threadgroup) | |
2105 | { | |
2106 | LIST_HEAD(preloaded_csets); | |
2107 | struct task_struct *task; | |
2108 | int ret; | |
2109 | ||
2110 | /* look up all src csets */ | |
2111 | down_read(&css_set_rwsem); | |
2112 | rcu_read_lock(); | |
2113 | task = leader; | |
2114 | do { | |
2115 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2116 | &preloaded_csets); | |
2117 | if (!threadgroup) | |
2118 | break; | |
2119 | } while_each_thread(leader, task); | |
2120 | rcu_read_unlock(); | |
2121 | up_read(&css_set_rwsem); | |
2122 | ||
2123 | /* prepare dst csets and commit */ | |
2124 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2125 | if (!ret) | |
2126 | ret = cgroup_migrate(dst_cgrp, leader, threadgroup); | |
2127 | ||
2128 | cgroup_migrate_finish(&preloaded_csets); | |
2129 | return ret; | |
74a1166d BB |
2130 | } |
2131 | ||
2132 | /* | |
2133 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2134 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2135 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2136 | */ |
74a1166d | 2137 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2138 | { |
bbcb81d0 | 2139 | struct task_struct *tsk; |
c69e8d9c | 2140 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2141 | int ret; |
2142 | ||
74a1166d BB |
2143 | if (!cgroup_lock_live_group(cgrp)) |
2144 | return -ENODEV; | |
2145 | ||
b78949eb MSB |
2146 | retry_find_task: |
2147 | rcu_read_lock(); | |
bbcb81d0 | 2148 | if (pid) { |
73507f33 | 2149 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2150 | if (!tsk) { |
2151 | rcu_read_unlock(); | |
dd4b0a46 | 2152 | ret = -ESRCH; |
b78949eb | 2153 | goto out_unlock_cgroup; |
bbcb81d0 | 2154 | } |
74a1166d BB |
2155 | /* |
2156 | * even if we're attaching all tasks in the thread group, we | |
2157 | * only need to check permissions on one of them. | |
2158 | */ | |
c69e8d9c | 2159 | tcred = __task_cred(tsk); |
14a590c3 EB |
2160 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
2161 | !uid_eq(cred->euid, tcred->uid) && | |
2162 | !uid_eq(cred->euid, tcred->suid)) { | |
c69e8d9c | 2163 | rcu_read_unlock(); |
b78949eb MSB |
2164 | ret = -EACCES; |
2165 | goto out_unlock_cgroup; | |
bbcb81d0 | 2166 | } |
b78949eb MSB |
2167 | } else |
2168 | tsk = current; | |
cd3d0952 TH |
2169 | |
2170 | if (threadgroup) | |
b78949eb | 2171 | tsk = tsk->group_leader; |
c4c27fbd MG |
2172 | |
2173 | /* | |
14a40ffc | 2174 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2175 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2176 | * with no rt_runtime allocated. Just say no. | |
2177 | */ | |
14a40ffc | 2178 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd MG |
2179 | ret = -EINVAL; |
2180 | rcu_read_unlock(); | |
2181 | goto out_unlock_cgroup; | |
2182 | } | |
2183 | ||
b78949eb MSB |
2184 | get_task_struct(tsk); |
2185 | rcu_read_unlock(); | |
2186 | ||
2187 | threadgroup_lock(tsk); | |
2188 | if (threadgroup) { | |
2189 | if (!thread_group_leader(tsk)) { | |
2190 | /* | |
2191 | * a race with de_thread from another thread's exec() | |
2192 | * may strip us of our leadership, if this happens, | |
2193 | * there is no choice but to throw this task away and | |
2194 | * try again; this is | |
2195 | * "double-double-toil-and-trouble-check locking". | |
2196 | */ | |
2197 | threadgroup_unlock(tsk); | |
2198 | put_task_struct(tsk); | |
2199 | goto retry_find_task; | |
2200 | } | |
081aa458 LZ |
2201 | } |
2202 | ||
2203 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
2204 | ||
cd3d0952 TH |
2205 | threadgroup_unlock(tsk); |
2206 | ||
bbcb81d0 | 2207 | put_task_struct(tsk); |
b78949eb | 2208 | out_unlock_cgroup: |
47cfcd09 | 2209 | mutex_unlock(&cgroup_mutex); |
bbcb81d0 PM |
2210 | return ret; |
2211 | } | |
2212 | ||
7ae1bad9 TH |
2213 | /** |
2214 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2215 | * @from: attach to all cgroups of a given task | |
2216 | * @tsk: the task to be attached | |
2217 | */ | |
2218 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2219 | { | |
3dd06ffa | 2220 | struct cgroup_root *root; |
7ae1bad9 TH |
2221 | int retval = 0; |
2222 | ||
47cfcd09 | 2223 | mutex_lock(&cgroup_mutex); |
985ed670 | 2224 | for_each_root(root) { |
96d365e0 TH |
2225 | struct cgroup *from_cgrp; |
2226 | ||
3dd06ffa | 2227 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2228 | continue; |
2229 | ||
96d365e0 TH |
2230 | down_read(&css_set_rwsem); |
2231 | from_cgrp = task_cgroup_from_root(from, root); | |
2232 | up_read(&css_set_rwsem); | |
7ae1bad9 | 2233 | |
6f4b7e63 | 2234 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2235 | if (retval) |
2236 | break; | |
2237 | } | |
47cfcd09 | 2238 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2239 | |
2240 | return retval; | |
2241 | } | |
2242 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2243 | ||
182446d0 TH |
2244 | static int cgroup_tasks_write(struct cgroup_subsys_state *css, |
2245 | struct cftype *cft, u64 pid) | |
74a1166d | 2246 | { |
182446d0 | 2247 | return attach_task_by_pid(css->cgroup, pid, false); |
74a1166d BB |
2248 | } |
2249 | ||
182446d0 TH |
2250 | static int cgroup_procs_write(struct cgroup_subsys_state *css, |
2251 | struct cftype *cft, u64 tgid) | |
af351026 | 2252 | { |
182446d0 | 2253 | return attach_task_by_pid(css->cgroup, tgid, true); |
af351026 PM |
2254 | } |
2255 | ||
182446d0 | 2256 | static int cgroup_release_agent_write(struct cgroup_subsys_state *css, |
4d3bb511 | 2257 | struct cftype *cft, char *buffer) |
e788e066 | 2258 | { |
3dd06ffa | 2259 | struct cgroup_root *root = css->cgroup->root; |
5f469907 TH |
2260 | |
2261 | BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX); | |
182446d0 | 2262 | if (!cgroup_lock_live_group(css->cgroup)) |
e788e066 | 2263 | return -ENODEV; |
69e943b7 | 2264 | spin_lock(&release_agent_path_lock); |
5f469907 TH |
2265 | strlcpy(root->release_agent_path, buffer, |
2266 | sizeof(root->release_agent_path)); | |
69e943b7 | 2267 | spin_unlock(&release_agent_path_lock); |
47cfcd09 | 2268 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2269 | return 0; |
2270 | } | |
2271 | ||
2da8ca82 | 2272 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2273 | { |
2da8ca82 | 2274 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2275 | |
e788e066 PM |
2276 | if (!cgroup_lock_live_group(cgrp)) |
2277 | return -ENODEV; | |
2278 | seq_puts(seq, cgrp->root->release_agent_path); | |
2279 | seq_putc(seq, '\n'); | |
47cfcd09 | 2280 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2281 | return 0; |
2282 | } | |
2283 | ||
2da8ca82 | 2284 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2285 | { |
2da8ca82 TH |
2286 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2287 | ||
2288 | seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); | |
e788e066 PM |
2289 | return 0; |
2290 | } | |
2291 | ||
2bd59d48 TH |
2292 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
2293 | size_t nbytes, loff_t off) | |
355e0c48 | 2294 | { |
2bd59d48 TH |
2295 | struct cgroup *cgrp = of->kn->parent->priv; |
2296 | struct cftype *cft = of->kn->priv; | |
2297 | struct cgroup_subsys_state *css; | |
a742c59d | 2298 | int ret; |
355e0c48 | 2299 | |
2bd59d48 TH |
2300 | /* |
2301 | * kernfs guarantees that a file isn't deleted with operations in | |
2302 | * flight, which means that the matching css is and stays alive and | |
2303 | * doesn't need to be pinned. The RCU locking is not necessary | |
2304 | * either. It's just for the convenience of using cgroup_css(). | |
2305 | */ | |
2306 | rcu_read_lock(); | |
2307 | css = cgroup_css(cgrp, cft->ss); | |
2308 | rcu_read_unlock(); | |
a742c59d TH |
2309 | |
2310 | if (cft->write_string) { | |
2311 | ret = cft->write_string(css, cft, strstrip(buf)); | |
2312 | } else if (cft->write_u64) { | |
2313 | unsigned long long v; | |
2314 | ret = kstrtoull(buf, 0, &v); | |
2315 | if (!ret) | |
2316 | ret = cft->write_u64(css, cft, v); | |
2317 | } else if (cft->write_s64) { | |
2318 | long long v; | |
2319 | ret = kstrtoll(buf, 0, &v); | |
2320 | if (!ret) | |
2321 | ret = cft->write_s64(css, cft, v); | |
2322 | } else if (cft->trigger) { | |
2323 | ret = cft->trigger(css, (unsigned int)cft->private); | |
e73d2c61 | 2324 | } else { |
a742c59d | 2325 | ret = -EINVAL; |
e73d2c61 | 2326 | } |
2bd59d48 | 2327 | |
a742c59d | 2328 | return ret ?: nbytes; |
355e0c48 PM |
2329 | } |
2330 | ||
6612f05b | 2331 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 2332 | { |
2bd59d48 | 2333 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
2334 | } |
2335 | ||
6612f05b | 2336 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 2337 | { |
2bd59d48 | 2338 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
2339 | } |
2340 | ||
6612f05b | 2341 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 2342 | { |
2bd59d48 | 2343 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
2344 | } |
2345 | ||
91796569 | 2346 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 2347 | { |
7da11279 TH |
2348 | struct cftype *cft = seq_cft(m); |
2349 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 2350 | |
2da8ca82 TH |
2351 | if (cft->seq_show) |
2352 | return cft->seq_show(m, arg); | |
e73d2c61 | 2353 | |
f4c753b7 | 2354 | if (cft->read_u64) |
896f5199 TH |
2355 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
2356 | else if (cft->read_s64) | |
2357 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
2358 | else | |
2359 | return -EINVAL; | |
2360 | return 0; | |
91796569 PM |
2361 | } |
2362 | ||
2bd59d48 TH |
2363 | static struct kernfs_ops cgroup_kf_single_ops = { |
2364 | .atomic_write_len = PAGE_SIZE, | |
2365 | .write = cgroup_file_write, | |
2366 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
2367 | }; |
2368 | ||
2bd59d48 TH |
2369 | static struct kernfs_ops cgroup_kf_ops = { |
2370 | .atomic_write_len = PAGE_SIZE, | |
2371 | .write = cgroup_file_write, | |
2372 | .seq_start = cgroup_seqfile_start, | |
2373 | .seq_next = cgroup_seqfile_next, | |
2374 | .seq_stop = cgroup_seqfile_stop, | |
2375 | .seq_show = cgroup_seqfile_show, | |
2376 | }; | |
ddbcc7e8 PM |
2377 | |
2378 | /* | |
2379 | * cgroup_rename - Only allow simple rename of directories in place. | |
2380 | */ | |
2bd59d48 TH |
2381 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
2382 | const char *new_name_str) | |
ddbcc7e8 | 2383 | { |
2bd59d48 | 2384 | struct cgroup *cgrp = kn->priv; |
65dff759 | 2385 | int ret; |
65dff759 | 2386 | |
2bd59d48 | 2387 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 2388 | return -ENOTDIR; |
2bd59d48 | 2389 | if (kn->parent != new_parent) |
ddbcc7e8 | 2390 | return -EIO; |
65dff759 | 2391 | |
6db8e85c TH |
2392 | /* |
2393 | * This isn't a proper migration and its usefulness is very | |
2394 | * limited. Disallow if sane_behavior. | |
2395 | */ | |
2396 | if (cgroup_sane_behavior(cgrp)) | |
2397 | return -EPERM; | |
099fca32 | 2398 | |
e1b2dc17 TH |
2399 | /* |
2400 | * We're gonna grab cgroup_tree_mutex which nests outside kernfs | |
2401 | * active_ref. kernfs_rename() doesn't require active_ref | |
2402 | * protection. Break them before grabbing cgroup_tree_mutex. | |
2403 | */ | |
2404 | kernfs_break_active_protection(new_parent); | |
2405 | kernfs_break_active_protection(kn); | |
099fca32 | 2406 | |
2bd59d48 TH |
2407 | mutex_lock(&cgroup_tree_mutex); |
2408 | mutex_lock(&cgroup_mutex); | |
099fca32 | 2409 | |
2bd59d48 | 2410 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 2411 | |
2bd59d48 TH |
2412 | mutex_unlock(&cgroup_mutex); |
2413 | mutex_unlock(&cgroup_tree_mutex); | |
e1b2dc17 TH |
2414 | |
2415 | kernfs_unbreak_active_protection(kn); | |
2416 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 2417 | return ret; |
099fca32 LZ |
2418 | } |
2419 | ||
49957f8e TH |
2420 | /* set uid and gid of cgroup dirs and files to that of the creator */ |
2421 | static int cgroup_kn_set_ugid(struct kernfs_node *kn) | |
2422 | { | |
2423 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, | |
2424 | .ia_uid = current_fsuid(), | |
2425 | .ia_gid = current_fsgid(), }; | |
2426 | ||
2427 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && | |
2428 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) | |
2429 | return 0; | |
2430 | ||
2431 | return kernfs_setattr(kn, &iattr); | |
2432 | } | |
2433 | ||
2bb566cb | 2434 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) |
ddbcc7e8 | 2435 | { |
8d7e6fb0 | 2436 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
2437 | struct kernfs_node *kn; |
2438 | struct lock_class_key *key = NULL; | |
49957f8e | 2439 | int ret; |
05ef1d7c | 2440 | |
2bd59d48 TH |
2441 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
2442 | key = &cft->lockdep_key; | |
2443 | #endif | |
2444 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
2445 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
2446 | NULL, false, key); | |
49957f8e TH |
2447 | if (IS_ERR(kn)) |
2448 | return PTR_ERR(kn); | |
2449 | ||
2450 | ret = cgroup_kn_set_ugid(kn); | |
2451 | if (ret) | |
2452 | kernfs_remove(kn); | |
2453 | return ret; | |
ddbcc7e8 PM |
2454 | } |
2455 | ||
b1f28d31 TH |
2456 | /** |
2457 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
2458 | * @cgrp: the target cgroup | |
b1f28d31 TH |
2459 | * @cfts: array of cftypes to be added |
2460 | * @is_add: whether to add or remove | |
2461 | * | |
2462 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
2bb566cb TH |
2463 | * For removals, this function never fails. If addition fails, this |
2464 | * function doesn't remove files already added. The caller is responsible | |
2465 | * for cleaning up. | |
b1f28d31 | 2466 | */ |
2bb566cb TH |
2467 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
2468 | bool is_add) | |
ddbcc7e8 | 2469 | { |
03b1cde6 | 2470 | struct cftype *cft; |
b1f28d31 TH |
2471 | int ret; |
2472 | ||
ace2bee8 | 2473 | lockdep_assert_held(&cgroup_tree_mutex); |
db0416b6 TH |
2474 | |
2475 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 2476 | /* does cft->flags tell us to skip this file on @cgrp? */ |
8cbbf2c9 TH |
2477 | if ((cft->flags & CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
2478 | continue; | |
873fe09e TH |
2479 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) |
2480 | continue; | |
f33fddc2 G |
2481 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
2482 | continue; | |
2483 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2484 | continue; | |
2485 | ||
2739d3cc | 2486 | if (is_add) { |
2bb566cb | 2487 | ret = cgroup_add_file(cgrp, cft); |
b1f28d31 | 2488 | if (ret) { |
2739d3cc | 2489 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", |
b1f28d31 TH |
2490 | cft->name, ret); |
2491 | return ret; | |
2492 | } | |
2739d3cc LZ |
2493 | } else { |
2494 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2495 | } |
ddbcc7e8 | 2496 | } |
b1f28d31 | 2497 | return 0; |
ddbcc7e8 PM |
2498 | } |
2499 | ||
21a2d343 | 2500 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
2501 | { |
2502 | LIST_HEAD(pending); | |
2bb566cb | 2503 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 2504 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 2505 | struct cgroup_subsys_state *css; |
9ccece80 | 2506 | int ret = 0; |
8e3f6541 | 2507 | |
21a2d343 | 2508 | lockdep_assert_held(&cgroup_tree_mutex); |
8e3f6541 | 2509 | |
e8c82d20 | 2510 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 2511 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
2512 | struct cgroup *cgrp = css->cgroup; |
2513 | ||
e8c82d20 LZ |
2514 | if (cgroup_is_dead(cgrp)) |
2515 | continue; | |
2516 | ||
21a2d343 | 2517 | ret = cgroup_addrm_files(cgrp, cfts, is_add); |
9ccece80 TH |
2518 | if (ret) |
2519 | break; | |
8e3f6541 | 2520 | } |
21a2d343 TH |
2521 | |
2522 | if (is_add && !ret) | |
2523 | kernfs_activate(root->kn); | |
9ccece80 | 2524 | return ret; |
8e3f6541 TH |
2525 | } |
2526 | ||
2da440a2 | 2527 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 2528 | { |
2bb566cb | 2529 | struct cftype *cft; |
8e3f6541 | 2530 | |
2bd59d48 TH |
2531 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
2532 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
2533 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
2534 | kfree(cft->kf_ops); | |
2535 | cft->kf_ops = NULL; | |
2da440a2 | 2536 | cft->ss = NULL; |
2bd59d48 | 2537 | } |
2da440a2 TH |
2538 | } |
2539 | ||
2bd59d48 | 2540 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
2541 | { |
2542 | struct cftype *cft; | |
2543 | ||
2bd59d48 TH |
2544 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
2545 | struct kernfs_ops *kf_ops; | |
2546 | ||
0adb0704 TH |
2547 | WARN_ON(cft->ss || cft->kf_ops); |
2548 | ||
2bd59d48 TH |
2549 | if (cft->seq_start) |
2550 | kf_ops = &cgroup_kf_ops; | |
2551 | else | |
2552 | kf_ops = &cgroup_kf_single_ops; | |
2553 | ||
2554 | /* | |
2555 | * Ugh... if @cft wants a custom max_write_len, we need to | |
2556 | * make a copy of kf_ops to set its atomic_write_len. | |
2557 | */ | |
2558 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
2559 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
2560 | if (!kf_ops) { | |
2561 | cgroup_exit_cftypes(cfts); | |
2562 | return -ENOMEM; | |
2563 | } | |
2564 | kf_ops->atomic_write_len = cft->max_write_len; | |
2565 | } | |
8e3f6541 | 2566 | |
2bd59d48 | 2567 | cft->kf_ops = kf_ops; |
2bb566cb | 2568 | cft->ss = ss; |
2bd59d48 | 2569 | } |
2bb566cb | 2570 | |
2bd59d48 | 2571 | return 0; |
2da440a2 TH |
2572 | } |
2573 | ||
21a2d343 TH |
2574 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
2575 | { | |
2576 | lockdep_assert_held(&cgroup_tree_mutex); | |
2577 | ||
2578 | if (!cfts || !cfts[0].ss) | |
2579 | return -ENOENT; | |
2580 | ||
2581 | list_del(&cfts->node); | |
2582 | cgroup_apply_cftypes(cfts, false); | |
2583 | cgroup_exit_cftypes(cfts); | |
2584 | return 0; | |
8e3f6541 | 2585 | } |
8e3f6541 | 2586 | |
79578621 TH |
2587 | /** |
2588 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
2589 | * @cfts: zero-length name terminated array of cftypes |
2590 | * | |
2bb566cb TH |
2591 | * Unregister @cfts. Files described by @cfts are removed from all |
2592 | * existing cgroups and all future cgroups won't have them either. This | |
2593 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
2594 | * |
2595 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 2596 | * registered. |
79578621 | 2597 | */ |
2bb566cb | 2598 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 2599 | { |
21a2d343 | 2600 | int ret; |
79578621 | 2601 | |
21a2d343 TH |
2602 | mutex_lock(&cgroup_tree_mutex); |
2603 | ret = cgroup_rm_cftypes_locked(cfts); | |
2604 | mutex_unlock(&cgroup_tree_mutex); | |
2605 | return ret; | |
80b13586 TH |
2606 | } |
2607 | ||
8e3f6541 TH |
2608 | /** |
2609 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2610 | * @ss: target cgroup subsystem | |
2611 | * @cfts: zero-length name terminated array of cftypes | |
2612 | * | |
2613 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2614 | * existing cgroups to which @ss is attached and all future cgroups will | |
2615 | * have them too. This function can be called anytime whether @ss is | |
2616 | * attached or not. | |
2617 | * | |
2618 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2619 | * function currently returns 0 as long as @cfts registration is successful | |
2620 | * even if some file creation attempts on existing cgroups fail. | |
2621 | */ | |
03b1cde6 | 2622 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 2623 | { |
9ccece80 | 2624 | int ret; |
8e3f6541 | 2625 | |
dc5736ed LZ |
2626 | if (!cfts || cfts[0].name[0] == '\0') |
2627 | return 0; | |
2bb566cb | 2628 | |
2bd59d48 TH |
2629 | ret = cgroup_init_cftypes(ss, cfts); |
2630 | if (ret) | |
2631 | return ret; | |
79578621 | 2632 | |
21a2d343 TH |
2633 | mutex_lock(&cgroup_tree_mutex); |
2634 | ||
0adb0704 | 2635 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 2636 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 2637 | if (ret) |
21a2d343 | 2638 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 2639 | |
21a2d343 | 2640 | mutex_unlock(&cgroup_tree_mutex); |
9ccece80 | 2641 | return ret; |
79578621 TH |
2642 | } |
2643 | ||
a043e3b2 LZ |
2644 | /** |
2645 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2646 | * @cgrp: the cgroup in question | |
2647 | * | |
2648 | * Return the number of tasks in the cgroup. | |
2649 | */ | |
07bc356e | 2650 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2651 | { |
2652 | int count = 0; | |
69d0206c | 2653 | struct cgrp_cset_link *link; |
817929ec | 2654 | |
96d365e0 | 2655 | down_read(&css_set_rwsem); |
69d0206c TH |
2656 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
2657 | count += atomic_read(&link->cset->refcount); | |
96d365e0 | 2658 | up_read(&css_set_rwsem); |
bbcb81d0 PM |
2659 | return count; |
2660 | } | |
2661 | ||
53fa5261 | 2662 | /** |
492eb21b TH |
2663 | * css_next_child - find the next child of a given css |
2664 | * @pos_css: the current position (%NULL to initiate traversal) | |
2665 | * @parent_css: css whose children to walk | |
53fa5261 | 2666 | * |
492eb21b | 2667 | * This function returns the next child of @parent_css and should be called |
87fb54f1 TH |
2668 | * under either cgroup_mutex or RCU read lock. The only requirement is |
2669 | * that @parent_css and @pos_css are accessible. The next sibling is | |
2670 | * guaranteed to be returned regardless of their states. | |
53fa5261 | 2671 | */ |
492eb21b TH |
2672 | struct cgroup_subsys_state * |
2673 | css_next_child(struct cgroup_subsys_state *pos_css, | |
2674 | struct cgroup_subsys_state *parent_css) | |
53fa5261 | 2675 | { |
492eb21b TH |
2676 | struct cgroup *pos = pos_css ? pos_css->cgroup : NULL; |
2677 | struct cgroup *cgrp = parent_css->cgroup; | |
53fa5261 TH |
2678 | struct cgroup *next; |
2679 | ||
ace2bee8 | 2680 | cgroup_assert_mutexes_or_rcu_locked(); |
53fa5261 TH |
2681 | |
2682 | /* | |
2683 | * @pos could already have been removed. Once a cgroup is removed, | |
2684 | * its ->sibling.next is no longer updated when its next sibling | |
ea15f8cc TH |
2685 | * changes. As CGRP_DEAD assertion is serialized and happens |
2686 | * before the cgroup is taken off the ->sibling list, if we see it | |
2687 | * unasserted, it's guaranteed that the next sibling hasn't | |
2688 | * finished its grace period even if it's already removed, and thus | |
2689 | * safe to dereference from this RCU critical section. If | |
2690 | * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed | |
2691 | * to be visible as %true here. | |
3b287a50 TH |
2692 | * |
2693 | * If @pos is dead, its next pointer can't be dereferenced; | |
2694 | * however, as each cgroup is given a monotonically increasing | |
2695 | * unique serial number and always appended to the sibling list, | |
2696 | * the next one can be found by walking the parent's children until | |
2697 | * we see a cgroup with higher serial number than @pos's. While | |
2698 | * this path can be slower, it's taken only when either the current | |
2699 | * cgroup is removed or iteration and removal race. | |
53fa5261 | 2700 | */ |
3b287a50 TH |
2701 | if (!pos) { |
2702 | next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling); | |
2703 | } else if (likely(!cgroup_is_dead(pos))) { | |
53fa5261 | 2704 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); |
3b287a50 TH |
2705 | } else { |
2706 | list_for_each_entry_rcu(next, &cgrp->children, sibling) | |
2707 | if (next->serial_nr > pos->serial_nr) | |
2708 | break; | |
53fa5261 TH |
2709 | } |
2710 | ||
492eb21b TH |
2711 | if (&next->sibling == &cgrp->children) |
2712 | return NULL; | |
2713 | ||
ca8bdcaf | 2714 | return cgroup_css(next, parent_css->ss); |
53fa5261 | 2715 | } |
53fa5261 | 2716 | |
574bd9f7 | 2717 | /** |
492eb21b | 2718 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 2719 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 2720 | * @root: css whose descendants to walk |
574bd9f7 | 2721 | * |
492eb21b | 2722 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
2723 | * to visit for pre-order traversal of @root's descendants. @root is |
2724 | * included in the iteration and the first node to be visited. | |
75501a6d | 2725 | * |
87fb54f1 TH |
2726 | * While this function requires cgroup_mutex or RCU read locking, it |
2727 | * doesn't require the whole traversal to be contained in a single critical | |
2728 | * section. This function will return the correct next descendant as long | |
2729 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
574bd9f7 | 2730 | */ |
492eb21b TH |
2731 | struct cgroup_subsys_state * |
2732 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
2733 | struct cgroup_subsys_state *root) | |
574bd9f7 | 2734 | { |
492eb21b | 2735 | struct cgroup_subsys_state *next; |
574bd9f7 | 2736 | |
ace2bee8 | 2737 | cgroup_assert_mutexes_or_rcu_locked(); |
574bd9f7 | 2738 | |
bd8815a6 | 2739 | /* if first iteration, visit @root */ |
7805d000 | 2740 | if (!pos) |
bd8815a6 | 2741 | return root; |
574bd9f7 TH |
2742 | |
2743 | /* visit the first child if exists */ | |
492eb21b | 2744 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
2745 | if (next) |
2746 | return next; | |
2747 | ||
2748 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b TH |
2749 | while (pos != root) { |
2750 | next = css_next_child(pos, css_parent(pos)); | |
75501a6d | 2751 | if (next) |
574bd9f7 | 2752 | return next; |
492eb21b | 2753 | pos = css_parent(pos); |
7805d000 | 2754 | } |
574bd9f7 TH |
2755 | |
2756 | return NULL; | |
2757 | } | |
574bd9f7 | 2758 | |
12a9d2fe | 2759 | /** |
492eb21b TH |
2760 | * css_rightmost_descendant - return the rightmost descendant of a css |
2761 | * @pos: css of interest | |
12a9d2fe | 2762 | * |
492eb21b TH |
2763 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
2764 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 2765 | * subtree of @pos. |
75501a6d | 2766 | * |
87fb54f1 TH |
2767 | * While this function requires cgroup_mutex or RCU read locking, it |
2768 | * doesn't require the whole traversal to be contained in a single critical | |
2769 | * section. This function will return the correct rightmost descendant as | |
2770 | * long as @pos is accessible. | |
12a9d2fe | 2771 | */ |
492eb21b TH |
2772 | struct cgroup_subsys_state * |
2773 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 2774 | { |
492eb21b | 2775 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 2776 | |
ace2bee8 | 2777 | cgroup_assert_mutexes_or_rcu_locked(); |
12a9d2fe TH |
2778 | |
2779 | do { | |
2780 | last = pos; | |
2781 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
2782 | pos = NULL; | |
492eb21b | 2783 | css_for_each_child(tmp, last) |
12a9d2fe TH |
2784 | pos = tmp; |
2785 | } while (pos); | |
2786 | ||
2787 | return last; | |
2788 | } | |
12a9d2fe | 2789 | |
492eb21b TH |
2790 | static struct cgroup_subsys_state * |
2791 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 2792 | { |
492eb21b | 2793 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
2794 | |
2795 | do { | |
2796 | last = pos; | |
492eb21b | 2797 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
2798 | } while (pos); |
2799 | ||
2800 | return last; | |
2801 | } | |
2802 | ||
2803 | /** | |
492eb21b | 2804 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 2805 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 2806 | * @root: css whose descendants to walk |
574bd9f7 | 2807 | * |
492eb21b | 2808 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
2809 | * to visit for post-order traversal of @root's descendants. @root is |
2810 | * included in the iteration and the last node to be visited. | |
75501a6d | 2811 | * |
87fb54f1 TH |
2812 | * While this function requires cgroup_mutex or RCU read locking, it |
2813 | * doesn't require the whole traversal to be contained in a single critical | |
2814 | * section. This function will return the correct next descendant as long | |
2815 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
2816 | * @cgroup. | |
574bd9f7 | 2817 | */ |
492eb21b TH |
2818 | struct cgroup_subsys_state * |
2819 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
2820 | struct cgroup_subsys_state *root) | |
574bd9f7 | 2821 | { |
492eb21b | 2822 | struct cgroup_subsys_state *next; |
574bd9f7 | 2823 | |
ace2bee8 | 2824 | cgroup_assert_mutexes_or_rcu_locked(); |
574bd9f7 | 2825 | |
58b79a91 TH |
2826 | /* if first iteration, visit leftmost descendant which may be @root */ |
2827 | if (!pos) | |
2828 | return css_leftmost_descendant(root); | |
574bd9f7 | 2829 | |
bd8815a6 TH |
2830 | /* if we visited @root, we're done */ |
2831 | if (pos == root) | |
2832 | return NULL; | |
2833 | ||
574bd9f7 | 2834 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
492eb21b | 2835 | next = css_next_child(pos, css_parent(pos)); |
75501a6d | 2836 | if (next) |
492eb21b | 2837 | return css_leftmost_descendant(next); |
574bd9f7 TH |
2838 | |
2839 | /* no sibling left, visit parent */ | |
bd8815a6 | 2840 | return css_parent(pos); |
574bd9f7 | 2841 | } |
574bd9f7 | 2842 | |
0942eeee | 2843 | /** |
72ec7029 | 2844 | * css_advance_task_iter - advance a task itererator to the next css_set |
0942eeee TH |
2845 | * @it: the iterator to advance |
2846 | * | |
2847 | * Advance @it to the next css_set to walk. | |
d515876e | 2848 | */ |
72ec7029 | 2849 | static void css_advance_task_iter(struct css_task_iter *it) |
d515876e TH |
2850 | { |
2851 | struct list_head *l = it->cset_link; | |
2852 | struct cgrp_cset_link *link; | |
2853 | struct css_set *cset; | |
2854 | ||
2855 | /* Advance to the next non-empty css_set */ | |
2856 | do { | |
2857 | l = l->next; | |
72ec7029 | 2858 | if (l == &it->origin_css->cgroup->cset_links) { |
d515876e TH |
2859 | it->cset_link = NULL; |
2860 | return; | |
2861 | } | |
2862 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
2863 | cset = link->cset; | |
c7561128 TH |
2864 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); |
2865 | ||
d515876e | 2866 | it->cset_link = l; |
c7561128 TH |
2867 | |
2868 | if (!list_empty(&cset->tasks)) | |
2869 | it->task = cset->tasks.next; | |
2870 | else | |
2871 | it->task = cset->mg_tasks.next; | |
d515876e TH |
2872 | } |
2873 | ||
0942eeee | 2874 | /** |
72ec7029 TH |
2875 | * css_task_iter_start - initiate task iteration |
2876 | * @css: the css to walk tasks of | |
0942eeee TH |
2877 | * @it: the task iterator to use |
2878 | * | |
72ec7029 TH |
2879 | * Initiate iteration through the tasks of @css. The caller can call |
2880 | * css_task_iter_next() to walk through the tasks until the function | |
2881 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
2882 | * called. | |
0942eeee TH |
2883 | * |
2884 | * Note that this function acquires a lock which is released when the | |
2885 | * iteration finishes. The caller can't sleep while iteration is in | |
2886 | * progress. | |
2887 | */ | |
72ec7029 TH |
2888 | void css_task_iter_start(struct cgroup_subsys_state *css, |
2889 | struct css_task_iter *it) | |
96d365e0 | 2890 | __acquires(css_set_rwsem) |
817929ec | 2891 | { |
56fde9e0 TH |
2892 | /* no one should try to iterate before mounting cgroups */ |
2893 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 2894 | |
96d365e0 | 2895 | down_read(&css_set_rwsem); |
c59cd3d8 | 2896 | |
72ec7029 TH |
2897 | it->origin_css = css; |
2898 | it->cset_link = &css->cgroup->cset_links; | |
c59cd3d8 | 2899 | |
72ec7029 | 2900 | css_advance_task_iter(it); |
817929ec PM |
2901 | } |
2902 | ||
0942eeee | 2903 | /** |
72ec7029 | 2904 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
2905 | * @it: the task iterator being iterated |
2906 | * | |
2907 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
2908 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
2909 | * reaches the end. | |
0942eeee | 2910 | */ |
72ec7029 | 2911 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec PM |
2912 | { |
2913 | struct task_struct *res; | |
2914 | struct list_head *l = it->task; | |
c7561128 TH |
2915 | struct cgrp_cset_link *link = list_entry(it->cset_link, |
2916 | struct cgrp_cset_link, cset_link); | |
817929ec PM |
2917 | |
2918 | /* If the iterator cg is NULL, we have no tasks */ | |
69d0206c | 2919 | if (!it->cset_link) |
817929ec PM |
2920 | return NULL; |
2921 | res = list_entry(l, struct task_struct, cg_list); | |
c7561128 TH |
2922 | |
2923 | /* | |
2924 | * Advance iterator to find next entry. cset->tasks is consumed | |
2925 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
2926 | * next cset. | |
2927 | */ | |
817929ec | 2928 | l = l->next; |
c7561128 TH |
2929 | |
2930 | if (l == &link->cset->tasks) | |
2931 | l = link->cset->mg_tasks.next; | |
2932 | ||
2933 | if (l == &link->cset->mg_tasks) | |
72ec7029 | 2934 | css_advance_task_iter(it); |
c7561128 | 2935 | else |
817929ec | 2936 | it->task = l; |
c7561128 | 2937 | |
817929ec PM |
2938 | return res; |
2939 | } | |
2940 | ||
0942eeee | 2941 | /** |
72ec7029 | 2942 | * css_task_iter_end - finish task iteration |
0942eeee TH |
2943 | * @it: the task iterator to finish |
2944 | * | |
72ec7029 | 2945 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 2946 | */ |
72ec7029 | 2947 | void css_task_iter_end(struct css_task_iter *it) |
96d365e0 | 2948 | __releases(css_set_rwsem) |
31a7df01 | 2949 | { |
96d365e0 | 2950 | up_read(&css_set_rwsem); |
31a7df01 CW |
2951 | } |
2952 | ||
2953 | /** | |
8cc99345 TH |
2954 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
2955 | * @to: cgroup to which the tasks will be moved | |
2956 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 2957 | * |
eaf797ab TH |
2958 | * Locking rules between cgroup_post_fork() and the migration path |
2959 | * guarantee that, if a task is forking while being migrated, the new child | |
2960 | * is guaranteed to be either visible in the source cgroup after the | |
2961 | * parent's migration is complete or put into the target cgroup. No task | |
2962 | * can slip out of migration through forking. | |
31a7df01 | 2963 | */ |
8cc99345 | 2964 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 2965 | { |
952aaa12 TH |
2966 | LIST_HEAD(preloaded_csets); |
2967 | struct cgrp_cset_link *link; | |
72ec7029 | 2968 | struct css_task_iter it; |
e406d1cf | 2969 | struct task_struct *task; |
952aaa12 | 2970 | int ret; |
31a7df01 | 2971 | |
952aaa12 | 2972 | mutex_lock(&cgroup_mutex); |
31a7df01 | 2973 | |
952aaa12 TH |
2974 | /* all tasks in @from are being moved, all csets are source */ |
2975 | down_read(&css_set_rwsem); | |
2976 | list_for_each_entry(link, &from->cset_links, cset_link) | |
2977 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
2978 | up_read(&css_set_rwsem); | |
31a7df01 | 2979 | |
952aaa12 TH |
2980 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
2981 | if (ret) | |
2982 | goto out_err; | |
8cc99345 | 2983 | |
952aaa12 TH |
2984 | /* |
2985 | * Migrate tasks one-by-one until @form is empty. This fails iff | |
2986 | * ->can_attach() fails. | |
2987 | */ | |
e406d1cf TH |
2988 | do { |
2989 | css_task_iter_start(&from->dummy_css, &it); | |
2990 | task = css_task_iter_next(&it); | |
2991 | if (task) | |
2992 | get_task_struct(task); | |
2993 | css_task_iter_end(&it); | |
2994 | ||
2995 | if (task) { | |
952aaa12 | 2996 | ret = cgroup_migrate(to, task, false); |
e406d1cf TH |
2997 | put_task_struct(task); |
2998 | } | |
2999 | } while (task && !ret); | |
952aaa12 TH |
3000 | out_err: |
3001 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 3002 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 3003 | return ret; |
8cc99345 TH |
3004 | } |
3005 | ||
bbcb81d0 | 3006 | /* |
102a775e | 3007 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3008 | * |
3009 | * Reading this file can return large amounts of data if a cgroup has | |
3010 | * *lots* of attached tasks. So it may need several calls to read(), | |
3011 | * but we cannot guarantee that the information we produce is correct | |
3012 | * unless we produce it entirely atomically. | |
3013 | * | |
bbcb81d0 | 3014 | */ |
bbcb81d0 | 3015 | |
24528255 LZ |
3016 | /* which pidlist file are we talking about? */ |
3017 | enum cgroup_filetype { | |
3018 | CGROUP_FILE_PROCS, | |
3019 | CGROUP_FILE_TASKS, | |
3020 | }; | |
3021 | ||
3022 | /* | |
3023 | * A pidlist is a list of pids that virtually represents the contents of one | |
3024 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3025 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3026 | * to the cgroup. | |
3027 | */ | |
3028 | struct cgroup_pidlist { | |
3029 | /* | |
3030 | * used to find which pidlist is wanted. doesn't change as long as | |
3031 | * this particular list stays in the list. | |
3032 | */ | |
3033 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3034 | /* array of xids */ | |
3035 | pid_t *list; | |
3036 | /* how many elements the above list has */ | |
3037 | int length; | |
24528255 LZ |
3038 | /* each of these stored in a list by its cgroup */ |
3039 | struct list_head links; | |
3040 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3041 | struct cgroup *owner; | |
b1a21367 TH |
3042 | /* for delayed destruction */ |
3043 | struct delayed_work destroy_dwork; | |
24528255 LZ |
3044 | }; |
3045 | ||
d1d9fd33 BB |
3046 | /* |
3047 | * The following two functions "fix" the issue where there are more pids | |
3048 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3049 | * TODO: replace with a kernel-wide solution to this problem | |
3050 | */ | |
3051 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3052 | static void *pidlist_allocate(int count) | |
3053 | { | |
3054 | if (PIDLIST_TOO_LARGE(count)) | |
3055 | return vmalloc(count * sizeof(pid_t)); | |
3056 | else | |
3057 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3058 | } | |
b1a21367 | 3059 | |
d1d9fd33 BB |
3060 | static void pidlist_free(void *p) |
3061 | { | |
3062 | if (is_vmalloc_addr(p)) | |
3063 | vfree(p); | |
3064 | else | |
3065 | kfree(p); | |
3066 | } | |
d1d9fd33 | 3067 | |
b1a21367 TH |
3068 | /* |
3069 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
3070 | * should be left afterwards. | |
3071 | */ | |
3072 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
3073 | { | |
3074 | struct cgroup_pidlist *l, *tmp_l; | |
3075 | ||
3076 | mutex_lock(&cgrp->pidlist_mutex); | |
3077 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
3078 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
3079 | mutex_unlock(&cgrp->pidlist_mutex); | |
3080 | ||
3081 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
3082 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
3083 | } | |
3084 | ||
3085 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
3086 | { | |
3087 | struct delayed_work *dwork = to_delayed_work(work); | |
3088 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
3089 | destroy_dwork); | |
3090 | struct cgroup_pidlist *tofree = NULL; | |
3091 | ||
3092 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
3093 | |
3094 | /* | |
04502365 TH |
3095 | * Destroy iff we didn't get queued again. The state won't change |
3096 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 3097 | */ |
04502365 | 3098 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
3099 | list_del(&l->links); |
3100 | pidlist_free(l->list); | |
3101 | put_pid_ns(l->key.ns); | |
3102 | tofree = l; | |
3103 | } | |
3104 | ||
b1a21367 TH |
3105 | mutex_unlock(&l->owner->pidlist_mutex); |
3106 | kfree(tofree); | |
3107 | } | |
3108 | ||
bbcb81d0 | 3109 | /* |
102a775e | 3110 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 3111 | * Returns the number of unique elements. |
bbcb81d0 | 3112 | */ |
6ee211ad | 3113 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 3114 | { |
102a775e | 3115 | int src, dest = 1; |
102a775e BB |
3116 | |
3117 | /* | |
3118 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3119 | * edge cases first; no work needs to be done for either | |
3120 | */ | |
3121 | if (length == 0 || length == 1) | |
3122 | return length; | |
3123 | /* src and dest walk down the list; dest counts unique elements */ | |
3124 | for (src = 1; src < length; src++) { | |
3125 | /* find next unique element */ | |
3126 | while (list[src] == list[src-1]) { | |
3127 | src++; | |
3128 | if (src == length) | |
3129 | goto after; | |
3130 | } | |
3131 | /* dest always points to where the next unique element goes */ | |
3132 | list[dest] = list[src]; | |
3133 | dest++; | |
3134 | } | |
3135 | after: | |
102a775e BB |
3136 | return dest; |
3137 | } | |
3138 | ||
afb2bc14 TH |
3139 | /* |
3140 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
3141 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
3142 | * different per namespace, each namespace needs differently sorted list, | |
3143 | * making it impossible to use, for example, single rbtree of member tasks | |
3144 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
3145 | * per open file is dangerous, so cgroup had to implement shared pool of | |
3146 | * pidlists keyed by cgroup and namespace. | |
3147 | * | |
3148 | * All this extra complexity was caused by the original implementation | |
3149 | * committing to an entirely unnecessary property. In the long term, we | |
3150 | * want to do away with it. Explicitly scramble sort order if | |
3151 | * sane_behavior so that no such expectation exists in the new interface. | |
3152 | * | |
3153 | * Scrambling is done by swapping every two consecutive bits, which is | |
3154 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
3155 | */ | |
3156 | static pid_t pid_fry(pid_t pid) | |
3157 | { | |
3158 | unsigned a = pid & 0x55555555; | |
3159 | unsigned b = pid & 0xAAAAAAAA; | |
3160 | ||
3161 | return (a << 1) | (b >> 1); | |
3162 | } | |
3163 | ||
3164 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
3165 | { | |
3166 | if (cgroup_sane_behavior(cgrp)) | |
3167 | return pid_fry(pid); | |
3168 | else | |
3169 | return pid; | |
3170 | } | |
3171 | ||
102a775e BB |
3172 | static int cmppid(const void *a, const void *b) |
3173 | { | |
3174 | return *(pid_t *)a - *(pid_t *)b; | |
3175 | } | |
3176 | ||
afb2bc14 TH |
3177 | static int fried_cmppid(const void *a, const void *b) |
3178 | { | |
3179 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
3180 | } | |
3181 | ||
e6b81710 TH |
3182 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
3183 | enum cgroup_filetype type) | |
3184 | { | |
3185 | struct cgroup_pidlist *l; | |
3186 | /* don't need task_nsproxy() if we're looking at ourself */ | |
3187 | struct pid_namespace *ns = task_active_pid_ns(current); | |
3188 | ||
3189 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
3190 | ||
3191 | list_for_each_entry(l, &cgrp->pidlists, links) | |
3192 | if (l->key.type == type && l->key.ns == ns) | |
3193 | return l; | |
3194 | return NULL; | |
3195 | } | |
3196 | ||
72a8cb30 BB |
3197 | /* |
3198 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3199 | * returns with the lock on that pidlist already held, and takes care | |
3200 | * of the use count, or returns NULL with no locks held if we're out of | |
3201 | * memory. | |
3202 | */ | |
e6b81710 TH |
3203 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
3204 | enum cgroup_filetype type) | |
72a8cb30 BB |
3205 | { |
3206 | struct cgroup_pidlist *l; | |
b70cc5fd | 3207 | |
e6b81710 TH |
3208 | lockdep_assert_held(&cgrp->pidlist_mutex); |
3209 | ||
3210 | l = cgroup_pidlist_find(cgrp, type); | |
3211 | if (l) | |
3212 | return l; | |
3213 | ||
72a8cb30 | 3214 | /* entry not found; create a new one */ |
f4f4be2b | 3215 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 3216 | if (!l) |
72a8cb30 | 3217 | return l; |
e6b81710 | 3218 | |
b1a21367 | 3219 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 3220 | l->key.type = type; |
e6b81710 TH |
3221 | /* don't need task_nsproxy() if we're looking at ourself */ |
3222 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
3223 | l->owner = cgrp; |
3224 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
3225 | return l; |
3226 | } | |
3227 | ||
102a775e BB |
3228 | /* |
3229 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3230 | */ | |
72a8cb30 BB |
3231 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3232 | struct cgroup_pidlist **lp) | |
102a775e BB |
3233 | { |
3234 | pid_t *array; | |
3235 | int length; | |
3236 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 3237 | struct css_task_iter it; |
817929ec | 3238 | struct task_struct *tsk; |
102a775e BB |
3239 | struct cgroup_pidlist *l; |
3240 | ||
4bac00d1 TH |
3241 | lockdep_assert_held(&cgrp->pidlist_mutex); |
3242 | ||
102a775e BB |
3243 | /* |
3244 | * If cgroup gets more users after we read count, we won't have | |
3245 | * enough space - tough. This race is indistinguishable to the | |
3246 | * caller from the case that the additional cgroup users didn't | |
3247 | * show up until sometime later on. | |
3248 | */ | |
3249 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3250 | array = pidlist_allocate(length); |
102a775e BB |
3251 | if (!array) |
3252 | return -ENOMEM; | |
3253 | /* now, populate the array */ | |
72ec7029 TH |
3254 | css_task_iter_start(&cgrp->dummy_css, &it); |
3255 | while ((tsk = css_task_iter_next(&it))) { | |
102a775e | 3256 | if (unlikely(n == length)) |
817929ec | 3257 | break; |
102a775e | 3258 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3259 | if (type == CGROUP_FILE_PROCS) |
3260 | pid = task_tgid_vnr(tsk); | |
3261 | else | |
3262 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3263 | if (pid > 0) /* make sure to only use valid results */ |
3264 | array[n++] = pid; | |
817929ec | 3265 | } |
72ec7029 | 3266 | css_task_iter_end(&it); |
102a775e BB |
3267 | length = n; |
3268 | /* now sort & (if procs) strip out duplicates */ | |
afb2bc14 TH |
3269 | if (cgroup_sane_behavior(cgrp)) |
3270 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); | |
3271 | else | |
3272 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3273 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 3274 | length = pidlist_uniq(array, length); |
e6b81710 | 3275 | |
e6b81710 | 3276 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 3277 | if (!l) { |
e6b81710 | 3278 | mutex_unlock(&cgrp->pidlist_mutex); |
d1d9fd33 | 3279 | pidlist_free(array); |
72a8cb30 | 3280 | return -ENOMEM; |
102a775e | 3281 | } |
e6b81710 TH |
3282 | |
3283 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 3284 | pidlist_free(l->list); |
102a775e BB |
3285 | l->list = array; |
3286 | l->length = length; | |
72a8cb30 | 3287 | *lp = l; |
102a775e | 3288 | return 0; |
bbcb81d0 PM |
3289 | } |
3290 | ||
846c7bb0 | 3291 | /** |
a043e3b2 | 3292 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3293 | * @stats: cgroupstats to fill information into |
3294 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3295 | * been requested. | |
a043e3b2 LZ |
3296 | * |
3297 | * Build and fill cgroupstats so that taskstats can export it to user | |
3298 | * space. | |
846c7bb0 BS |
3299 | */ |
3300 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3301 | { | |
2bd59d48 | 3302 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 3303 | struct cgroup *cgrp; |
72ec7029 | 3304 | struct css_task_iter it; |
846c7bb0 | 3305 | struct task_struct *tsk; |
33d283be | 3306 | |
2bd59d48 TH |
3307 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
3308 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
3309 | kernfs_type(kn) != KERNFS_DIR) | |
3310 | return -EINVAL; | |
3311 | ||
bad34660 LZ |
3312 | mutex_lock(&cgroup_mutex); |
3313 | ||
846c7bb0 | 3314 | /* |
2bd59d48 TH |
3315 | * We aren't being called from kernfs and there's no guarantee on |
3316 | * @kn->priv's validity. For this and css_tryget_from_dir(), | |
3317 | * @kn->priv is RCU safe. Let's do the RCU dancing. | |
846c7bb0 | 3318 | */ |
2bd59d48 TH |
3319 | rcu_read_lock(); |
3320 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 3321 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 3322 | rcu_read_unlock(); |
bad34660 | 3323 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
3324 | return -ENOENT; |
3325 | } | |
bad34660 | 3326 | rcu_read_unlock(); |
846c7bb0 | 3327 | |
72ec7029 TH |
3328 | css_task_iter_start(&cgrp->dummy_css, &it); |
3329 | while ((tsk = css_task_iter_next(&it))) { | |
846c7bb0 BS |
3330 | switch (tsk->state) { |
3331 | case TASK_RUNNING: | |
3332 | stats->nr_running++; | |
3333 | break; | |
3334 | case TASK_INTERRUPTIBLE: | |
3335 | stats->nr_sleeping++; | |
3336 | break; | |
3337 | case TASK_UNINTERRUPTIBLE: | |
3338 | stats->nr_uninterruptible++; | |
3339 | break; | |
3340 | case TASK_STOPPED: | |
3341 | stats->nr_stopped++; | |
3342 | break; | |
3343 | default: | |
3344 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3345 | stats->nr_io_wait++; | |
3346 | break; | |
3347 | } | |
3348 | } | |
72ec7029 | 3349 | css_task_iter_end(&it); |
846c7bb0 | 3350 | |
bad34660 | 3351 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 3352 | return 0; |
846c7bb0 BS |
3353 | } |
3354 | ||
8f3ff208 | 3355 | |
bbcb81d0 | 3356 | /* |
102a775e | 3357 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3358 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3359 | * in the cgroup->l->list array. |
bbcb81d0 | 3360 | */ |
cc31edce | 3361 | |
102a775e | 3362 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3363 | { |
cc31edce PM |
3364 | /* |
3365 | * Initially we receive a position value that corresponds to | |
3366 | * one more than the last pid shown (or 0 on the first call or | |
3367 | * after a seek to the start). Use a binary-search to find the | |
3368 | * next pid to display, if any | |
3369 | */ | |
2bd59d48 | 3370 | struct kernfs_open_file *of = s->private; |
7da11279 | 3371 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 3372 | struct cgroup_pidlist *l; |
7da11279 | 3373 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 3374 | int index = 0, pid = *pos; |
4bac00d1 TH |
3375 | int *iter, ret; |
3376 | ||
3377 | mutex_lock(&cgrp->pidlist_mutex); | |
3378 | ||
3379 | /* | |
5d22444f | 3380 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 3381 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 3382 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
3383 | * could already have been destroyed. |
3384 | */ | |
5d22444f TH |
3385 | if (of->priv) |
3386 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
3387 | |
3388 | /* | |
3389 | * Either this is the first start() after open or the matching | |
3390 | * pidlist has been destroyed inbetween. Create a new one. | |
3391 | */ | |
5d22444f TH |
3392 | if (!of->priv) { |
3393 | ret = pidlist_array_load(cgrp, type, | |
3394 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
3395 | if (ret) |
3396 | return ERR_PTR(ret); | |
3397 | } | |
5d22444f | 3398 | l = of->priv; |
cc31edce | 3399 | |
cc31edce | 3400 | if (pid) { |
102a775e | 3401 | int end = l->length; |
20777766 | 3402 | |
cc31edce PM |
3403 | while (index < end) { |
3404 | int mid = (index + end) / 2; | |
afb2bc14 | 3405 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
3406 | index = mid; |
3407 | break; | |
afb2bc14 | 3408 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
3409 | index = mid + 1; |
3410 | else | |
3411 | end = mid; | |
3412 | } | |
3413 | } | |
3414 | /* If we're off the end of the array, we're done */ | |
102a775e | 3415 | if (index >= l->length) |
cc31edce PM |
3416 | return NULL; |
3417 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3418 | iter = l->list + index; |
afb2bc14 | 3419 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
3420 | return iter; |
3421 | } | |
3422 | ||
102a775e | 3423 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3424 | { |
2bd59d48 | 3425 | struct kernfs_open_file *of = s->private; |
5d22444f | 3426 | struct cgroup_pidlist *l = of->priv; |
62236858 | 3427 | |
5d22444f TH |
3428 | if (l) |
3429 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 3430 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 3431 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
3432 | } |
3433 | ||
102a775e | 3434 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3435 | { |
2bd59d48 | 3436 | struct kernfs_open_file *of = s->private; |
5d22444f | 3437 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
3438 | pid_t *p = v; |
3439 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3440 | /* |
3441 | * Advance to the next pid in the array. If this goes off the | |
3442 | * end, we're done | |
3443 | */ | |
3444 | p++; | |
3445 | if (p >= end) { | |
3446 | return NULL; | |
3447 | } else { | |
7da11279 | 3448 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
3449 | return p; |
3450 | } | |
3451 | } | |
3452 | ||
102a775e | 3453 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3454 | { |
3455 | return seq_printf(s, "%d\n", *(int *)v); | |
3456 | } | |
bbcb81d0 | 3457 | |
102a775e BB |
3458 | /* |
3459 | * seq_operations functions for iterating on pidlists through seq_file - | |
3460 | * independent of whether it's tasks or procs | |
3461 | */ | |
3462 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3463 | .start = cgroup_pidlist_start, | |
3464 | .stop = cgroup_pidlist_stop, | |
3465 | .next = cgroup_pidlist_next, | |
3466 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3467 | }; |
3468 | ||
182446d0 TH |
3469 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
3470 | struct cftype *cft) | |
81a6a5cd | 3471 | { |
182446d0 | 3472 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
3473 | } |
3474 | ||
182446d0 TH |
3475 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
3476 | struct cftype *cft, u64 val) | |
6379c106 | 3477 | { |
182446d0 | 3478 | clear_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
6379c106 | 3479 | if (val) |
182446d0 | 3480 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 3481 | else |
182446d0 | 3482 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
3483 | return 0; |
3484 | } | |
3485 | ||
182446d0 TH |
3486 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
3487 | struct cftype *cft) | |
97978e6d | 3488 | { |
182446d0 | 3489 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
3490 | } |
3491 | ||
182446d0 TH |
3492 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
3493 | struct cftype *cft, u64 val) | |
97978e6d DL |
3494 | { |
3495 | if (val) | |
182446d0 | 3496 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 3497 | else |
182446d0 | 3498 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
3499 | return 0; |
3500 | } | |
3501 | ||
d5c56ced | 3502 | static struct cftype cgroup_base_files[] = { |
81a6a5cd | 3503 | { |
d5c56ced | 3504 | .name = "cgroup.procs", |
6612f05b TH |
3505 | .seq_start = cgroup_pidlist_start, |
3506 | .seq_next = cgroup_pidlist_next, | |
3507 | .seq_stop = cgroup_pidlist_stop, | |
3508 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 3509 | .private = CGROUP_FILE_PROCS, |
74a1166d | 3510 | .write_u64 = cgroup_procs_write, |
74a1166d | 3511 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 3512 | }, |
97978e6d DL |
3513 | { |
3514 | .name = "cgroup.clone_children", | |
873fe09e | 3515 | .flags = CFTYPE_INSANE, |
97978e6d DL |
3516 | .read_u64 = cgroup_clone_children_read, |
3517 | .write_u64 = cgroup_clone_children_write, | |
3518 | }, | |
873fe09e TH |
3519 | { |
3520 | .name = "cgroup.sane_behavior", | |
3521 | .flags = CFTYPE_ONLY_ON_ROOT, | |
2da8ca82 | 3522 | .seq_show = cgroup_sane_behavior_show, |
873fe09e | 3523 | }, |
d5c56ced TH |
3524 | |
3525 | /* | |
3526 | * Historical crazy stuff. These don't have "cgroup." prefix and | |
3527 | * don't exist if sane_behavior. If you're depending on these, be | |
3528 | * prepared to be burned. | |
3529 | */ | |
3530 | { | |
3531 | .name = "tasks", | |
3532 | .flags = CFTYPE_INSANE, /* use "procs" instead */ | |
6612f05b TH |
3533 | .seq_start = cgroup_pidlist_start, |
3534 | .seq_next = cgroup_pidlist_next, | |
3535 | .seq_stop = cgroup_pidlist_stop, | |
3536 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 3537 | .private = CGROUP_FILE_TASKS, |
d5c56ced | 3538 | .write_u64 = cgroup_tasks_write, |
d5c56ced TH |
3539 | .mode = S_IRUGO | S_IWUSR, |
3540 | }, | |
3541 | { | |
3542 | .name = "notify_on_release", | |
3543 | .flags = CFTYPE_INSANE, | |
3544 | .read_u64 = cgroup_read_notify_on_release, | |
3545 | .write_u64 = cgroup_write_notify_on_release, | |
3546 | }, | |
6e6ff25b TH |
3547 | { |
3548 | .name = "release_agent", | |
cc5943a7 | 3549 | .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 3550 | .seq_show = cgroup_release_agent_show, |
6e6ff25b | 3551 | .write_string = cgroup_release_agent_write, |
5f469907 | 3552 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 3553 | }, |
db0416b6 | 3554 | { } /* terminate */ |
bbcb81d0 PM |
3555 | }; |
3556 | ||
13af07df | 3557 | /** |
628f7cd4 | 3558 | * cgroup_populate_dir - create subsys files in a cgroup directory |
13af07df | 3559 | * @cgrp: target cgroup |
13af07df | 3560 | * @subsys_mask: mask of the subsystem ids whose files should be added |
bee55099 TH |
3561 | * |
3562 | * On failure, no file is added. | |
13af07df | 3563 | */ |
628f7cd4 | 3564 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
ddbcc7e8 | 3565 | { |
ddbcc7e8 | 3566 | struct cgroup_subsys *ss; |
b420ba7d | 3567 | int i, ret = 0; |
bbcb81d0 | 3568 | |
8e3f6541 | 3569 | /* process cftsets of each subsystem */ |
b420ba7d | 3570 | for_each_subsys(ss, i) { |
0adb0704 | 3571 | struct cftype *cfts; |
b420ba7d TH |
3572 | |
3573 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 3574 | continue; |
8e3f6541 | 3575 | |
0adb0704 TH |
3576 | list_for_each_entry(cfts, &ss->cfts, node) { |
3577 | ret = cgroup_addrm_files(cgrp, cfts, true); | |
bee55099 TH |
3578 | if (ret < 0) |
3579 | goto err; | |
3580 | } | |
ddbcc7e8 | 3581 | } |
ddbcc7e8 | 3582 | return 0; |
bee55099 TH |
3583 | err: |
3584 | cgroup_clear_dir(cgrp, subsys_mask); | |
3585 | return ret; | |
ddbcc7e8 PM |
3586 | } |
3587 | ||
0c21ead1 TH |
3588 | /* |
3589 | * css destruction is four-stage process. | |
3590 | * | |
3591 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
3592 | * Implemented in kill_css(). | |
3593 | * | |
3594 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
3595 | * and thus css_tryget() is guaranteed to fail, the css can be offlined | |
3596 | * by invoking offline_css(). After offlining, the base ref is put. | |
3597 | * Implemented in css_killed_work_fn(). | |
3598 | * | |
3599 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
3600 | * accessors are inside RCU read sections. css_release() schedules the | |
3601 | * RCU callback. | |
3602 | * | |
3603 | * 4. After the grace period, the css can be freed. Implemented in | |
3604 | * css_free_work_fn(). | |
3605 | * | |
3606 | * It is actually hairier because both step 2 and 4 require process context | |
3607 | * and thus involve punting to css->destroy_work adding two additional | |
3608 | * steps to the already complex sequence. | |
3609 | */ | |
35ef10da | 3610 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
3611 | { |
3612 | struct cgroup_subsys_state *css = | |
35ef10da | 3613 | container_of(work, struct cgroup_subsys_state, destroy_work); |
0c21ead1 | 3614 | struct cgroup *cgrp = css->cgroup; |
48ddbe19 | 3615 | |
0ae78e0b TH |
3616 | if (css->parent) |
3617 | css_put(css->parent); | |
3618 | ||
0c21ead1 | 3619 | css->ss->css_free(css); |
2bd59d48 | 3620 | cgroup_put(cgrp); |
48ddbe19 TH |
3621 | } |
3622 | ||
0c21ead1 | 3623 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
3624 | { |
3625 | struct cgroup_subsys_state *css = | |
0c21ead1 | 3626 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 3627 | |
35ef10da | 3628 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 3629 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
3630 | } |
3631 | ||
d3daf28d TH |
3632 | static void css_release(struct percpu_ref *ref) |
3633 | { | |
3634 | struct cgroup_subsys_state *css = | |
3635 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
3636 | ||
01a97140 | 3637 | RCU_INIT_POINTER(css->cgroup->subsys[css->ss->id], NULL); |
0c21ead1 | 3638 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
3639 | } |
3640 | ||
623f926b TH |
3641 | static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss, |
3642 | struct cgroup *cgrp) | |
ddbcc7e8 | 3643 | { |
bd89aabc | 3644 | css->cgroup = cgrp; |
72c97e54 | 3645 | css->ss = ss; |
ddbcc7e8 | 3646 | css->flags = 0; |
0ae78e0b TH |
3647 | |
3648 | if (cgrp->parent) | |
ca8bdcaf | 3649 | css->parent = cgroup_css(cgrp->parent, ss); |
0ae78e0b | 3650 | else |
38b53aba | 3651 | css->flags |= CSS_ROOT; |
48ddbe19 | 3652 | |
ca8bdcaf | 3653 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
3654 | } |
3655 | ||
2a4ac633 | 3656 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 3657 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 3658 | { |
623f926b | 3659 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
3660 | int ret = 0; |
3661 | ||
ace2bee8 | 3662 | lockdep_assert_held(&cgroup_tree_mutex); |
a31f2d3f TH |
3663 | lockdep_assert_held(&cgroup_mutex); |
3664 | ||
92fb9748 | 3665 | if (ss->css_online) |
eb95419b | 3666 | ret = ss->css_online(css); |
ae7f164a | 3667 | if (!ret) { |
eb95419b | 3668 | css->flags |= CSS_ONLINE; |
f20104de | 3669 | css->cgroup->nr_css++; |
aec25020 | 3670 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 3671 | } |
b1929db4 | 3672 | return ret; |
a31f2d3f TH |
3673 | } |
3674 | ||
2a4ac633 | 3675 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 3676 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 3677 | { |
623f926b | 3678 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f | 3679 | |
ace2bee8 | 3680 | lockdep_assert_held(&cgroup_tree_mutex); |
a31f2d3f TH |
3681 | lockdep_assert_held(&cgroup_mutex); |
3682 | ||
3683 | if (!(css->flags & CSS_ONLINE)) | |
3684 | return; | |
3685 | ||
d7eeac19 | 3686 | if (ss->css_offline) |
eb95419b | 3687 | ss->css_offline(css); |
a31f2d3f | 3688 | |
eb95419b | 3689 | css->flags &= ~CSS_ONLINE; |
09a503ea | 3690 | css->cgroup->nr_css--; |
aec25020 | 3691 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], css); |
a31f2d3f TH |
3692 | } |
3693 | ||
c81c925a TH |
3694 | /** |
3695 | * create_css - create a cgroup_subsys_state | |
3696 | * @cgrp: the cgroup new css will be associated with | |
3697 | * @ss: the subsys of new css | |
3698 | * | |
3699 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
3700 | * css is online and installed in @cgrp with all interface files created. | |
3701 | * Returns 0 on success, -errno on failure. | |
3702 | */ | |
3703 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) | |
3704 | { | |
3705 | struct cgroup *parent = cgrp->parent; | |
3706 | struct cgroup_subsys_state *css; | |
3707 | int err; | |
3708 | ||
c81c925a TH |
3709 | lockdep_assert_held(&cgroup_mutex); |
3710 | ||
3711 | css = ss->css_alloc(cgroup_css(parent, ss)); | |
3712 | if (IS_ERR(css)) | |
3713 | return PTR_ERR(css); | |
3714 | ||
3715 | err = percpu_ref_init(&css->refcnt, css_release); | |
3716 | if (err) | |
3eb59ec6 | 3717 | goto err_free_css; |
c81c925a TH |
3718 | |
3719 | init_css(css, ss, cgrp); | |
3720 | ||
aec25020 | 3721 | err = cgroup_populate_dir(cgrp, 1 << ss->id); |
c81c925a | 3722 | if (err) |
3eb59ec6 | 3723 | goto err_free_percpu_ref; |
c81c925a TH |
3724 | |
3725 | err = online_css(css); | |
3726 | if (err) | |
3eb59ec6 | 3727 | goto err_clear_dir; |
c81c925a | 3728 | |
59f5296b | 3729 | cgroup_get(cgrp); |
c81c925a TH |
3730 | css_get(css->parent); |
3731 | ||
3732 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && | |
3733 | parent->parent) { | |
3734 | pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", | |
3735 | current->comm, current->pid, ss->name); | |
3736 | if (!strcmp(ss->name, "memory")) | |
3737 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
3738 | ss->warned_broken_hierarchy = true; | |
3739 | } | |
3740 | ||
3741 | return 0; | |
3742 | ||
3eb59ec6 | 3743 | err_clear_dir: |
32d01dc7 | 3744 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3eb59ec6 | 3745 | err_free_percpu_ref: |
c81c925a | 3746 | percpu_ref_cancel_init(&css->refcnt); |
3eb59ec6 | 3747 | err_free_css: |
c81c925a TH |
3748 | ss->css_free(css); |
3749 | return err; | |
3750 | } | |
3751 | ||
2bd59d48 | 3752 | /** |
a043e3b2 LZ |
3753 | * cgroup_create - create a cgroup |
3754 | * @parent: cgroup that will be parent of the new cgroup | |
e61734c5 | 3755 | * @name: name of the new cgroup |
2bd59d48 | 3756 | * @mode: mode to set on new cgroup |
ddbcc7e8 | 3757 | */ |
e61734c5 | 3758 | static long cgroup_create(struct cgroup *parent, const char *name, |
2bd59d48 | 3759 | umode_t mode) |
ddbcc7e8 | 3760 | { |
bd89aabc | 3761 | struct cgroup *cgrp; |
3dd06ffa | 3762 | struct cgroup_root *root = parent->root; |
b58c8998 | 3763 | int ssid, err; |
ddbcc7e8 | 3764 | struct cgroup_subsys *ss; |
2bd59d48 | 3765 | struct kernfs_node *kn; |
ddbcc7e8 | 3766 | |
a2dd4247 TH |
3767 | /* |
3768 | * XXX: The default hierarchy isn't fully implemented yet. Block | |
3769 | * !root cgroup creation on it for now. | |
3770 | */ | |
3771 | if (root == &cgrp_dfl_root) | |
3772 | return -EINVAL; | |
ddbcc7e8 | 3773 | |
0a950f65 | 3774 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc PM |
3775 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3776 | if (!cgrp) | |
ddbcc7e8 PM |
3777 | return -ENOMEM; |
3778 | ||
ace2bee8 | 3779 | mutex_lock(&cgroup_tree_mutex); |
65dff759 | 3780 | |
976c06bc TH |
3781 | /* |
3782 | * Only live parents can have children. Note that the liveliness | |
3783 | * check isn't strictly necessary because cgroup_mkdir() and | |
3784 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
3785 | * anyway so that locking is contained inside cgroup proper and we | |
3786 | * don't get nasty surprises if we ever grow another caller. | |
3787 | */ | |
3788 | if (!cgroup_lock_live_group(parent)) { | |
3789 | err = -ENODEV; | |
ace2bee8 | 3790 | goto err_unlock_tree; |
0ab02ca8 LZ |
3791 | } |
3792 | ||
3793 | /* | |
3794 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
3795 | * a half-baked cgroup. | |
3796 | */ | |
3797 | cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL); | |
3798 | if (cgrp->id < 0) { | |
3799 | err = -ENOMEM; | |
3800 | goto err_unlock; | |
976c06bc TH |
3801 | } |
3802 | ||
cc31edce | 3803 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 3804 | |
bd89aabc | 3805 | cgrp->parent = parent; |
0ae78e0b | 3806 | cgrp->dummy_css.parent = &parent->dummy_css; |
bd89aabc | 3807 | cgrp->root = parent->root; |
ddbcc7e8 | 3808 | |
b6abdb0e LZ |
3809 | if (notify_on_release(parent)) |
3810 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3811 | ||
2260e7fc TH |
3812 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
3813 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 3814 | |
2bd59d48 | 3815 | /* create the directory */ |
e61734c5 | 3816 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 TH |
3817 | if (IS_ERR(kn)) { |
3818 | err = PTR_ERR(kn); | |
0ab02ca8 | 3819 | goto err_free_id; |
2bd59d48 TH |
3820 | } |
3821 | cgrp->kn = kn; | |
ddbcc7e8 | 3822 | |
4e139afc | 3823 | /* |
6f30558f TH |
3824 | * This extra ref will be put in cgroup_free_fn() and guarantees |
3825 | * that @cgrp->kn is always accessible. | |
4e139afc | 3826 | */ |
6f30558f | 3827 | kernfs_get(kn); |
ddbcc7e8 | 3828 | |
00356bd5 | 3829 | cgrp->serial_nr = cgroup_serial_nr_next++; |
53fa5261 | 3830 | |
4e139afc | 3831 | /* allocation complete, commit to creation */ |
4e139afc | 3832 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); |
3c9c825b | 3833 | atomic_inc(&root->nr_cgrps); |
59f5296b | 3834 | cgroup_get(parent); |
415cf07a | 3835 | |
0d80255e TH |
3836 | /* |
3837 | * @cgrp is now fully operational. If something fails after this | |
3838 | * point, it'll be released via the normal destruction path. | |
3839 | */ | |
4e96ee8e LZ |
3840 | idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
3841 | ||
49957f8e TH |
3842 | err = cgroup_kn_set_ugid(kn); |
3843 | if (err) | |
3844 | goto err_destroy; | |
3845 | ||
2bb566cb | 3846 | err = cgroup_addrm_files(cgrp, cgroup_base_files, true); |
628f7cd4 TH |
3847 | if (err) |
3848 | goto err_destroy; | |
3849 | ||
9d403e99 | 3850 | /* let's create and online css's */ |
b85d2040 | 3851 | for_each_subsys(ss, ssid) { |
f392e51c | 3852 | if (parent->child_subsys_mask & (1 << ssid)) { |
b85d2040 TH |
3853 | err = create_css(cgrp, ss); |
3854 | if (err) | |
3855 | goto err_destroy; | |
3856 | } | |
a8638030 | 3857 | } |
ddbcc7e8 | 3858 | |
f392e51c TH |
3859 | cgrp->child_subsys_mask = parent->child_subsys_mask; |
3860 | ||
2bd59d48 TH |
3861 | kernfs_activate(kn); |
3862 | ||
ddbcc7e8 | 3863 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 3864 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
3865 | |
3866 | return 0; | |
3867 | ||
0a950f65 | 3868 | err_free_id: |
4e96ee8e | 3869 | idr_remove(&root->cgroup_idr, cgrp->id); |
0ab02ca8 LZ |
3870 | err_unlock: |
3871 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 TH |
3872 | err_unlock_tree: |
3873 | mutex_unlock(&cgroup_tree_mutex); | |
bd89aabc | 3874 | kfree(cgrp); |
ddbcc7e8 | 3875 | return err; |
4b8b47eb TH |
3876 | |
3877 | err_destroy: | |
3878 | cgroup_destroy_locked(cgrp); | |
3879 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 3880 | mutex_unlock(&cgroup_tree_mutex); |
4b8b47eb | 3881 | return err; |
ddbcc7e8 PM |
3882 | } |
3883 | ||
2bd59d48 TH |
3884 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
3885 | umode_t mode) | |
ddbcc7e8 | 3886 | { |
2bd59d48 | 3887 | struct cgroup *parent = parent_kn->priv; |
e1b2dc17 | 3888 | int ret; |
ddbcc7e8 | 3889 | |
e1b2dc17 TH |
3890 | /* |
3891 | * cgroup_create() grabs cgroup_tree_mutex which nests outside | |
3892 | * kernfs active_ref and cgroup_create() already synchronizes | |
3893 | * properly against removal through cgroup_lock_live_group(). | |
3894 | * Break it before calling cgroup_create(). | |
3895 | */ | |
3896 | cgroup_get(parent); | |
3897 | kernfs_break_active_protection(parent_kn); | |
ddbcc7e8 | 3898 | |
e1b2dc17 TH |
3899 | ret = cgroup_create(parent, name, mode); |
3900 | ||
3901 | kernfs_unbreak_active_protection(parent_kn); | |
3902 | cgroup_put(parent); | |
3903 | return ret; | |
ddbcc7e8 PM |
3904 | } |
3905 | ||
223dbc38 TH |
3906 | /* |
3907 | * This is called when the refcnt of a css is confirmed to be killed. | |
3908 | * css_tryget() is now guaranteed to fail. | |
3909 | */ | |
3910 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 3911 | { |
223dbc38 TH |
3912 | struct cgroup_subsys_state *css = |
3913 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
3914 | struct cgroup *cgrp = css->cgroup; | |
d3daf28d | 3915 | |
ace2bee8 | 3916 | mutex_lock(&cgroup_tree_mutex); |
f20104de TH |
3917 | mutex_lock(&cgroup_mutex); |
3918 | ||
09a503ea TH |
3919 | /* |
3920 | * css_tryget() is guaranteed to fail now. Tell subsystems to | |
3921 | * initate destruction. | |
3922 | */ | |
3923 | offline_css(css); | |
3924 | ||
f20104de TH |
3925 | /* |
3926 | * If @cgrp is marked dead, it's waiting for refs of all css's to | |
3927 | * be disabled before proceeding to the second phase of cgroup | |
3928 | * destruction. If we are the last one, kick it off. | |
3929 | */ | |
09a503ea | 3930 | if (!cgrp->nr_css && cgroup_is_dead(cgrp)) |
f20104de TH |
3931 | cgroup_destroy_css_killed(cgrp); |
3932 | ||
3933 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 3934 | mutex_unlock(&cgroup_tree_mutex); |
09a503ea TH |
3935 | |
3936 | /* | |
3937 | * Put the css refs from kill_css(). Each css holds an extra | |
3938 | * reference to the cgroup's dentry and cgroup removal proceeds | |
3939 | * regardless of css refs. On the last put of each css, whenever | |
3940 | * that may be, the extra dentry ref is put so that dentry | |
3941 | * destruction happens only after all css's are released. | |
3942 | */ | |
3943 | css_put(css); | |
d3daf28d TH |
3944 | } |
3945 | ||
223dbc38 TH |
3946 | /* css kill confirmation processing requires process context, bounce */ |
3947 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
3948 | { |
3949 | struct cgroup_subsys_state *css = | |
3950 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
3951 | ||
223dbc38 | 3952 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 3953 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
3954 | } |
3955 | ||
f392e51c TH |
3956 | /** |
3957 | * kill_css - destroy a css | |
3958 | * @css: css to destroy | |
3959 | * | |
3960 | * This function initiates destruction of @css by removing cgroup interface | |
3961 | * files and putting its base reference. ->css_offline() will be invoked | |
3962 | * asynchronously once css_tryget() is guaranteed to fail and when the | |
3963 | * reference count reaches zero, @css will be released. | |
3964 | */ | |
3965 | static void kill_css(struct cgroup_subsys_state *css) | |
edae0c33 | 3966 | { |
94419627 TH |
3967 | lockdep_assert_held(&cgroup_tree_mutex); |
3968 | ||
2bd59d48 TH |
3969 | /* |
3970 | * This must happen before css is disassociated with its cgroup. | |
3971 | * See seq_css() for details. | |
3972 | */ | |
aec25020 | 3973 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3c14f8b4 | 3974 | |
edae0c33 TH |
3975 | /* |
3976 | * Killing would put the base ref, but we need to keep it alive | |
3977 | * until after ->css_offline(). | |
3978 | */ | |
3979 | css_get(css); | |
3980 | ||
3981 | /* | |
3982 | * cgroup core guarantees that, by the time ->css_offline() is | |
3983 | * invoked, no new css reference will be given out via | |
3984 | * css_tryget(). We can't simply call percpu_ref_kill() and | |
3985 | * proceed to offlining css's because percpu_ref_kill() doesn't | |
3986 | * guarantee that the ref is seen as killed on all CPUs on return. | |
3987 | * | |
3988 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
3989 | * css is confirmed to be seen as killed on all CPUs. | |
3990 | */ | |
3991 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
3992 | } |
3993 | ||
3994 | /** | |
3995 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
3996 | * @cgrp: cgroup to be destroyed | |
3997 | * | |
3998 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
3999 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
4000 | * guarantee that css_tryget() won't succeed by the time ->css_offline() is | |
4001 | * invoked. To satisfy all the requirements, destruction is implemented in | |
4002 | * the following two steps. | |
4003 | * | |
4004 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
4005 | * userland visible parts and start killing the percpu refcnts of | |
4006 | * css's. Set up so that the next stage will be kicked off once all | |
4007 | * the percpu refcnts are confirmed to be killed. | |
4008 | * | |
4009 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
4010 | * rest of destruction. Once all cgroup references are gone, the | |
4011 | * cgroup is RCU-freed. | |
4012 | * | |
4013 | * This function implements s1. After this step, @cgrp is gone as far as | |
4014 | * the userland is concerned and a new cgroup with the same name may be | |
4015 | * created. As cgroup doesn't care about the names internally, this | |
4016 | * doesn't cause any problem. | |
4017 | */ | |
42809dd4 TH |
4018 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4019 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4020 | { |
bb78a92f | 4021 | struct cgroup *child; |
2bd59d48 | 4022 | struct cgroup_subsys_state *css; |
ddd69148 | 4023 | bool empty; |
1c6727af | 4024 | int ssid; |
ddbcc7e8 | 4025 | |
ace2bee8 | 4026 | lockdep_assert_held(&cgroup_tree_mutex); |
42809dd4 TH |
4027 | lockdep_assert_held(&cgroup_mutex); |
4028 | ||
ddd69148 | 4029 | /* |
96d365e0 | 4030 | * css_set_rwsem synchronizes access to ->cset_links and prevents |
89c5509b | 4031 | * @cgrp from being removed while put_css_set() is in progress. |
ddd69148 | 4032 | */ |
96d365e0 | 4033 | down_read(&css_set_rwsem); |
bb78a92f | 4034 | empty = list_empty(&cgrp->cset_links); |
96d365e0 | 4035 | up_read(&css_set_rwsem); |
ddd69148 | 4036 | if (!empty) |
ddbcc7e8 | 4037 | return -EBUSY; |
a043e3b2 | 4038 | |
bb78a92f HD |
4039 | /* |
4040 | * Make sure there's no live children. We can't test ->children | |
4041 | * emptiness as dead children linger on it while being destroyed; | |
4042 | * otherwise, "rmdir parent/child parent" may fail with -EBUSY. | |
4043 | */ | |
4044 | empty = true; | |
4045 | rcu_read_lock(); | |
4046 | list_for_each_entry_rcu(child, &cgrp->children, sibling) { | |
4047 | empty = cgroup_is_dead(child); | |
4048 | if (!empty) | |
4049 | break; | |
4050 | } | |
4051 | rcu_read_unlock(); | |
4052 | if (!empty) | |
4053 | return -EBUSY; | |
4054 | ||
455050d2 TH |
4055 | /* |
4056 | * Mark @cgrp dead. This prevents further task migration and child | |
4057 | * creation by disabling cgroup_lock_live_group(). Note that | |
492eb21b | 4058 | * CGRP_DEAD assertion is depended upon by css_next_child() to |
455050d2 | 4059 | * resume iteration after dropping RCU read lock. See |
492eb21b | 4060 | * css_next_child() for details. |
455050d2 | 4061 | */ |
54766d4a | 4062 | set_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 | 4063 | |
88703267 | 4064 | /* |
edae0c33 TH |
4065 | * Initiate massacre of all css's. cgroup_destroy_css_killed() |
4066 | * will be invoked to perform the rest of destruction once the | |
4ac06017 TH |
4067 | * percpu refs of all css's are confirmed to be killed. This |
4068 | * involves removing the subsystem's files, drop cgroup_mutex. | |
88703267 | 4069 | */ |
4ac06017 | 4070 | mutex_unlock(&cgroup_mutex); |
1c6727af TH |
4071 | for_each_css(css, ssid, cgrp) |
4072 | kill_css(css); | |
4ac06017 | 4073 | mutex_lock(&cgroup_mutex); |
455050d2 | 4074 | |
455050d2 TH |
4075 | /* CGRP_DEAD is set, remove from ->release_list for the last time */ |
4076 | raw_spin_lock(&release_list_lock); | |
4077 | if (!list_empty(&cgrp->release_list)) | |
4078 | list_del_init(&cgrp->release_list); | |
4079 | raw_spin_unlock(&release_list_lock); | |
4080 | ||
4081 | /* | |
f20104de TH |
4082 | * If @cgrp has css's attached, the second stage of cgroup |
4083 | * destruction is kicked off from css_killed_work_fn() after the | |
4084 | * refs of all attached css's are killed. If @cgrp doesn't have | |
4085 | * any css, we kick it off here. | |
4086 | */ | |
4087 | if (!cgrp->nr_css) | |
4088 | cgroup_destroy_css_killed(cgrp); | |
4089 | ||
2bd59d48 TH |
4090 | /* remove @cgrp directory along with the base files */ |
4091 | mutex_unlock(&cgroup_mutex); | |
4092 | ||
455050d2 | 4093 | /* |
2bd59d48 TH |
4094 | * There are two control paths which try to determine cgroup from |
4095 | * dentry without going through kernfs - cgroupstats_build() and | |
4096 | * css_tryget_from_dir(). Those are supported by RCU protecting | |
4097 | * clearing of cgrp->kn->priv backpointer, which should happen | |
4098 | * after all files under it have been removed. | |
455050d2 | 4099 | */ |
6f30558f | 4100 | kernfs_remove(cgrp->kn); /* @cgrp has an extra ref on its kn */ |
2bd59d48 | 4101 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); |
2bd59d48 | 4102 | |
4ac06017 | 4103 | mutex_lock(&cgroup_mutex); |
455050d2 | 4104 | |
ea15f8cc TH |
4105 | return 0; |
4106 | }; | |
4107 | ||
d3daf28d | 4108 | /** |
f20104de | 4109 | * cgroup_destroy_css_killed - the second step of cgroup destruction |
d3daf28d TH |
4110 | * @work: cgroup->destroy_free_work |
4111 | * | |
4112 | * This function is invoked from a work item for a cgroup which is being | |
09a503ea TH |
4113 | * destroyed after all css's are offlined and performs the rest of |
4114 | * destruction. This is the second step of destruction described in the | |
4115 | * comment above cgroup_destroy_locked(). | |
d3daf28d | 4116 | */ |
f20104de | 4117 | static void cgroup_destroy_css_killed(struct cgroup *cgrp) |
ea15f8cc | 4118 | { |
ea15f8cc | 4119 | struct cgroup *parent = cgrp->parent; |
ea15f8cc | 4120 | |
ace2bee8 | 4121 | lockdep_assert_held(&cgroup_tree_mutex); |
f20104de | 4122 | lockdep_assert_held(&cgroup_mutex); |
ea15f8cc | 4123 | |
999cd8a4 | 4124 | /* delete this cgroup from parent->children */ |
eb6fd504 | 4125 | list_del_rcu(&cgrp->sibling); |
ed957793 | 4126 | |
59f5296b | 4127 | cgroup_put(cgrp); |
ddbcc7e8 | 4128 | |
bd89aabc | 4129 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd | 4130 | check_for_release(parent); |
ddbcc7e8 PM |
4131 | } |
4132 | ||
2bd59d48 | 4133 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 4134 | { |
2bd59d48 TH |
4135 | struct cgroup *cgrp = kn->priv; |
4136 | int ret = 0; | |
42809dd4 | 4137 | |
2bd59d48 TH |
4138 | /* |
4139 | * This is self-destruction but @kn can't be removed while this | |
4140 | * callback is in progress. Let's break active protection. Once | |
4141 | * the protection is broken, @cgrp can be destroyed at any point. | |
4142 | * Pin it so that it stays accessible. | |
4143 | */ | |
4144 | cgroup_get(cgrp); | |
4145 | kernfs_break_active_protection(kn); | |
42809dd4 | 4146 | |
ace2bee8 | 4147 | mutex_lock(&cgroup_tree_mutex); |
42809dd4 | 4148 | mutex_lock(&cgroup_mutex); |
8e3f6541 TH |
4149 | |
4150 | /* | |
2bd59d48 TH |
4151 | * @cgrp might already have been destroyed while we're trying to |
4152 | * grab the mutexes. | |
8e3f6541 | 4153 | */ |
2bd59d48 TH |
4154 | if (!cgroup_is_dead(cgrp)) |
4155 | ret = cgroup_destroy_locked(cgrp); | |
2bb566cb | 4156 | |
42809dd4 | 4157 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 4158 | mutex_unlock(&cgroup_tree_mutex); |
2bb566cb | 4159 | |
2bd59d48 TH |
4160 | kernfs_unbreak_active_protection(kn); |
4161 | cgroup_put(cgrp); | |
42809dd4 | 4162 | return ret; |
8e3f6541 TH |
4163 | } |
4164 | ||
2bd59d48 TH |
4165 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
4166 | .remount_fs = cgroup_remount, | |
4167 | .show_options = cgroup_show_options, | |
4168 | .mkdir = cgroup_mkdir, | |
4169 | .rmdir = cgroup_rmdir, | |
4170 | .rename = cgroup_rename, | |
4171 | }; | |
4172 | ||
06a11920 | 4173 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4174 | { |
ddbcc7e8 | 4175 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4176 | |
4177 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 4178 | |
ace2bee8 | 4179 | mutex_lock(&cgroup_tree_mutex); |
648bb56d TH |
4180 | mutex_lock(&cgroup_mutex); |
4181 | ||
0adb0704 | 4182 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 4183 | |
3dd06ffa TH |
4184 | /* Create the root cgroup state for this subsystem */ |
4185 | ss->root = &cgrp_dfl_root; | |
4186 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
4187 | /* We don't handle early failures gracefully */ |
4188 | BUG_ON(IS_ERR(css)); | |
3dd06ffa | 4189 | init_css(css, ss, &cgrp_dfl_root.cgrp); |
ddbcc7e8 | 4190 | |
e8d55fde | 4191 | /* Update the init_css_set to contain a subsys |
817929ec | 4192 | * pointer to this state - since the subsystem is |
e8d55fde | 4193 | * newly registered, all tasks and hence the |
3dd06ffa | 4194 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 4195 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 PM |
4196 | |
4197 | need_forkexit_callback |= ss->fork || ss->exit; | |
4198 | ||
e8d55fde LZ |
4199 | /* At system boot, before all subsystems have been |
4200 | * registered, no tasks have been forked, so we don't | |
4201 | * need to invoke fork callbacks here. */ | |
4202 | BUG_ON(!list_empty(&init_task.tasks)); | |
4203 | ||
ae7f164a | 4204 | BUG_ON(online_css(css)); |
a8638030 | 4205 | |
f392e51c | 4206 | cgrp_dfl_root.subsys_mask |= 1 << ss->id; |
cf5d5941 BB |
4207 | |
4208 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 4209 | mutex_unlock(&cgroup_tree_mutex); |
cf5d5941 | 4210 | } |
cf5d5941 | 4211 | |
ddbcc7e8 | 4212 | /** |
a043e3b2 LZ |
4213 | * cgroup_init_early - cgroup initialization at system boot |
4214 | * | |
4215 | * Initialize cgroups at system boot, and initialize any | |
4216 | * subsystems that request early init. | |
ddbcc7e8 PM |
4217 | */ |
4218 | int __init cgroup_init_early(void) | |
4219 | { | |
a2dd4247 TH |
4220 | static struct cgroup_sb_opts __initdata opts = |
4221 | { .flags = CGRP_ROOT_SANE_BEHAVIOR }; | |
30159ec7 | 4222 | struct cgroup_subsys *ss; |
ddbcc7e8 | 4223 | int i; |
30159ec7 | 4224 | |
3dd06ffa | 4225 | init_cgroup_root(&cgrp_dfl_root, &opts); |
a4ea1cc9 | 4226 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 4227 | |
3ed80a62 | 4228 | for_each_subsys(ss, i) { |
aec25020 | 4229 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
4230 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
4231 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 4232 | ss->id, ss->name); |
073219e9 TH |
4233 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
4234 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
4235 | ||
aec25020 | 4236 | ss->id = i; |
073219e9 | 4237 | ss->name = cgroup_subsys_name[i]; |
ddbcc7e8 PM |
4238 | |
4239 | if (ss->early_init) | |
4240 | cgroup_init_subsys(ss); | |
4241 | } | |
4242 | return 0; | |
4243 | } | |
4244 | ||
4245 | /** | |
a043e3b2 LZ |
4246 | * cgroup_init - cgroup initialization |
4247 | * | |
4248 | * Register cgroup filesystem and /proc file, and initialize | |
4249 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4250 | */ |
4251 | int __init cgroup_init(void) | |
4252 | { | |
30159ec7 | 4253 | struct cgroup_subsys *ss; |
0ac801fe | 4254 | unsigned long key; |
172a2c06 | 4255 | int ssid, err; |
ddbcc7e8 | 4256 | |
2bd59d48 | 4257 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files)); |
ddbcc7e8 | 4258 | |
985ed670 | 4259 | mutex_lock(&cgroup_tree_mutex); |
54e7b4eb | 4260 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 4261 | |
82fe9b0d TH |
4262 | /* Add init_css_set to the hash table */ |
4263 | key = css_set_hash(init_css_set.subsys); | |
4264 | hash_add(css_set_table, &init_css_set.hlist, key); | |
4265 | ||
3dd06ffa | 4266 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 4267 | |
54e7b4eb | 4268 | mutex_unlock(&cgroup_mutex); |
985ed670 | 4269 | mutex_unlock(&cgroup_tree_mutex); |
54e7b4eb | 4270 | |
172a2c06 TH |
4271 | for_each_subsys(ss, ssid) { |
4272 | if (!ss->early_init) | |
4273 | cgroup_init_subsys(ss); | |
4274 | ||
2d8f243a TH |
4275 | list_add_tail(&init_css_set.e_cset_node[ssid], |
4276 | &cgrp_dfl_root.cgrp.e_csets[ssid]); | |
4277 | ||
172a2c06 TH |
4278 | /* |
4279 | * cftype registration needs kmalloc and can't be done | |
4280 | * during early_init. Register base cftypes separately. | |
4281 | */ | |
4282 | if (ss->base_cftypes) | |
4283 | WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes)); | |
676db4af GKH |
4284 | } |
4285 | ||
676db4af | 4286 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
2bd59d48 TH |
4287 | if (!cgroup_kobj) |
4288 | return -ENOMEM; | |
676db4af | 4289 | |
ddbcc7e8 | 4290 | err = register_filesystem(&cgroup_fs_type); |
676db4af GKH |
4291 | if (err < 0) { |
4292 | kobject_put(cgroup_kobj); | |
2bd59d48 | 4293 | return err; |
676db4af | 4294 | } |
ddbcc7e8 | 4295 | |
46ae220b | 4296 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 4297 | return 0; |
ddbcc7e8 | 4298 | } |
b4f48b63 | 4299 | |
e5fca243 TH |
4300 | static int __init cgroup_wq_init(void) |
4301 | { | |
4302 | /* | |
4303 | * There isn't much point in executing destruction path in | |
4304 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 4305 | * Use 1 for @max_active. |
e5fca243 TH |
4306 | * |
4307 | * We would prefer to do this in cgroup_init() above, but that | |
4308 | * is called before init_workqueues(): so leave this until after. | |
4309 | */ | |
1a11533f | 4310 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 4311 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
4312 | |
4313 | /* | |
4314 | * Used to destroy pidlists and separate to serve as flush domain. | |
4315 | * Cap @max_active to 1 too. | |
4316 | */ | |
4317 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
4318 | 0, 1); | |
4319 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
4320 | ||
e5fca243 TH |
4321 | return 0; |
4322 | } | |
4323 | core_initcall(cgroup_wq_init); | |
4324 | ||
a424316c PM |
4325 | /* |
4326 | * proc_cgroup_show() | |
4327 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4328 | * - Used for /proc/<pid>/cgroup. | |
a424316c PM |
4329 | */ |
4330 | ||
4331 | /* TODO: Use a proper seq_file iterator */ | |
8d8b97ba | 4332 | int proc_cgroup_show(struct seq_file *m, void *v) |
a424316c PM |
4333 | { |
4334 | struct pid *pid; | |
4335 | struct task_struct *tsk; | |
e61734c5 | 4336 | char *buf, *path; |
a424316c | 4337 | int retval; |
3dd06ffa | 4338 | struct cgroup_root *root; |
a424316c PM |
4339 | |
4340 | retval = -ENOMEM; | |
e61734c5 | 4341 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
4342 | if (!buf) |
4343 | goto out; | |
4344 | ||
4345 | retval = -ESRCH; | |
4346 | pid = m->private; | |
4347 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4348 | if (!tsk) | |
4349 | goto out_free; | |
4350 | ||
4351 | retval = 0; | |
4352 | ||
4353 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 4354 | down_read(&css_set_rwsem); |
a424316c | 4355 | |
985ed670 | 4356 | for_each_root(root) { |
a424316c | 4357 | struct cgroup_subsys *ss; |
bd89aabc | 4358 | struct cgroup *cgrp; |
b85d2040 | 4359 | int ssid, count = 0; |
a424316c | 4360 | |
a2dd4247 | 4361 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible) |
985ed670 TH |
4362 | continue; |
4363 | ||
2c6ab6d2 | 4364 | seq_printf(m, "%d:", root->hierarchy_id); |
b85d2040 | 4365 | for_each_subsys(ss, ssid) |
f392e51c | 4366 | if (root->subsys_mask & (1 << ssid)) |
b85d2040 | 4367 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); |
c6d57f33 PM |
4368 | if (strlen(root->name)) |
4369 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4370 | root->name); | |
a424316c | 4371 | seq_putc(m, ':'); |
7717f7ba | 4372 | cgrp = task_cgroup_from_root(tsk, root); |
e61734c5 TH |
4373 | path = cgroup_path(cgrp, buf, PATH_MAX); |
4374 | if (!path) { | |
4375 | retval = -ENAMETOOLONG; | |
a424316c | 4376 | goto out_unlock; |
e61734c5 TH |
4377 | } |
4378 | seq_puts(m, path); | |
a424316c PM |
4379 | seq_putc(m, '\n'); |
4380 | } | |
4381 | ||
4382 | out_unlock: | |
96d365e0 | 4383 | up_read(&css_set_rwsem); |
a424316c PM |
4384 | mutex_unlock(&cgroup_mutex); |
4385 | put_task_struct(tsk); | |
4386 | out_free: | |
4387 | kfree(buf); | |
4388 | out: | |
4389 | return retval; | |
4390 | } | |
4391 | ||
a424316c PM |
4392 | /* Display information about each subsystem and each hierarchy */ |
4393 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4394 | { | |
30159ec7 | 4395 | struct cgroup_subsys *ss; |
a424316c | 4396 | int i; |
a424316c | 4397 | |
8bab8dde | 4398 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4399 | /* |
4400 | * ideally we don't want subsystems moving around while we do this. | |
4401 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4402 | * subsys/hierarchy state. | |
4403 | */ | |
a424316c | 4404 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
4405 | |
4406 | for_each_subsys(ss, i) | |
2c6ab6d2 PM |
4407 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4408 | ss->name, ss->root->hierarchy_id, | |
3c9c825b | 4409 | atomic_read(&ss->root->nr_cgrps), !ss->disabled); |
30159ec7 | 4410 | |
a424316c PM |
4411 | mutex_unlock(&cgroup_mutex); |
4412 | return 0; | |
4413 | } | |
4414 | ||
4415 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4416 | { | |
9dce07f1 | 4417 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4418 | } |
4419 | ||
828c0950 | 4420 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4421 | .open = cgroupstats_open, |
4422 | .read = seq_read, | |
4423 | .llseek = seq_lseek, | |
4424 | .release = single_release, | |
4425 | }; | |
4426 | ||
b4f48b63 | 4427 | /** |
eaf797ab | 4428 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 4429 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 4430 | * |
eaf797ab TH |
4431 | * A task is associated with the init_css_set until cgroup_post_fork() |
4432 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
4433 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
4434 | */ |
4435 | void cgroup_fork(struct task_struct *child) | |
4436 | { | |
eaf797ab | 4437 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 4438 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
4439 | } |
4440 | ||
817929ec | 4441 | /** |
a043e3b2 LZ |
4442 | * cgroup_post_fork - called on a new task after adding it to the task list |
4443 | * @child: the task in question | |
4444 | * | |
5edee61e TH |
4445 | * Adds the task to the list running through its css_set if necessary and |
4446 | * call the subsystem fork() callbacks. Has to be after the task is | |
4447 | * visible on the task list in case we race with the first call to | |
0942eeee | 4448 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 4449 | * list. |
a043e3b2 | 4450 | */ |
817929ec PM |
4451 | void cgroup_post_fork(struct task_struct *child) |
4452 | { | |
30159ec7 | 4453 | struct cgroup_subsys *ss; |
5edee61e TH |
4454 | int i; |
4455 | ||
3ce3230a | 4456 | /* |
eaf797ab TH |
4457 | * This may race against cgroup_enable_task_cg_links(). As that |
4458 | * function sets use_task_css_set_links before grabbing | |
4459 | * tasklist_lock and we just went through tasklist_lock to add | |
4460 | * @child, it's guaranteed that either we see the set | |
4461 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
4462 | * @child during its iteration. | |
4463 | * | |
4464 | * If we won the race, @child is associated with %current's | |
4465 | * css_set. Grabbing css_set_rwsem guarantees both that the | |
4466 | * association is stable, and, on completion of the parent's | |
4467 | * migration, @child is visible in the source of migration or | |
4468 | * already in the destination cgroup. This guarantee is necessary | |
4469 | * when implementing operations which need to migrate all tasks of | |
4470 | * a cgroup to another. | |
4471 | * | |
4472 | * Note that if we lose to cgroup_enable_task_cg_links(), @child | |
4473 | * will remain in init_css_set. This is safe because all tasks are | |
4474 | * in the init_css_set before cg_links is enabled and there's no | |
4475 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 4476 | */ |
817929ec | 4477 | if (use_task_css_set_links) { |
eaf797ab TH |
4478 | struct css_set *cset; |
4479 | ||
96d365e0 | 4480 | down_write(&css_set_rwsem); |
0e1d768f | 4481 | cset = task_css_set(current); |
eaf797ab TH |
4482 | if (list_empty(&child->cg_list)) { |
4483 | rcu_assign_pointer(child->cgroups, cset); | |
4484 | list_add(&child->cg_list, &cset->tasks); | |
4485 | get_css_set(cset); | |
4486 | } | |
96d365e0 | 4487 | up_write(&css_set_rwsem); |
817929ec | 4488 | } |
5edee61e TH |
4489 | |
4490 | /* | |
4491 | * Call ss->fork(). This must happen after @child is linked on | |
4492 | * css_set; otherwise, @child might change state between ->fork() | |
4493 | * and addition to css_set. | |
4494 | */ | |
4495 | if (need_forkexit_callback) { | |
3ed80a62 | 4496 | for_each_subsys(ss, i) |
5edee61e TH |
4497 | if (ss->fork) |
4498 | ss->fork(child); | |
5edee61e | 4499 | } |
817929ec | 4500 | } |
5edee61e | 4501 | |
b4f48b63 PM |
4502 | /** |
4503 | * cgroup_exit - detach cgroup from exiting task | |
4504 | * @tsk: pointer to task_struct of exiting process | |
4505 | * | |
4506 | * Description: Detach cgroup from @tsk and release it. | |
4507 | * | |
4508 | * Note that cgroups marked notify_on_release force every task in | |
4509 | * them to take the global cgroup_mutex mutex when exiting. | |
4510 | * This could impact scaling on very large systems. Be reluctant to | |
4511 | * use notify_on_release cgroups where very high task exit scaling | |
4512 | * is required on large systems. | |
4513 | * | |
0e1d768f TH |
4514 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
4515 | * call cgroup_exit() while the task is still competent to handle | |
4516 | * notify_on_release(), then leave the task attached to the root cgroup in | |
4517 | * each hierarchy for the remainder of its exit. No need to bother with | |
4518 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 4519 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 4520 | */ |
1ec41830 | 4521 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 4522 | { |
30159ec7 | 4523 | struct cgroup_subsys *ss; |
5abb8855 | 4524 | struct css_set *cset; |
eaf797ab | 4525 | bool put_cset = false; |
d41d5a01 | 4526 | int i; |
817929ec PM |
4527 | |
4528 | /* | |
0e1d768f TH |
4529 | * Unlink from @tsk from its css_set. As migration path can't race |
4530 | * with us, we can check cg_list without grabbing css_set_rwsem. | |
817929ec PM |
4531 | */ |
4532 | if (!list_empty(&tsk->cg_list)) { | |
96d365e0 | 4533 | down_write(&css_set_rwsem); |
0e1d768f | 4534 | list_del_init(&tsk->cg_list); |
96d365e0 | 4535 | up_write(&css_set_rwsem); |
0e1d768f | 4536 | put_cset = true; |
817929ec PM |
4537 | } |
4538 | ||
b4f48b63 | 4539 | /* Reassign the task to the init_css_set. */ |
a8ad805c TH |
4540 | cset = task_css_set(tsk); |
4541 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 | 4542 | |
1ec41830 | 4543 | if (need_forkexit_callback) { |
3ed80a62 TH |
4544 | /* see cgroup_post_fork() for details */ |
4545 | for_each_subsys(ss, i) { | |
d41d5a01 | 4546 | if (ss->exit) { |
eb95419b TH |
4547 | struct cgroup_subsys_state *old_css = cset->subsys[i]; |
4548 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 4549 | |
eb95419b | 4550 | ss->exit(css, old_css, tsk); |
d41d5a01 PZ |
4551 | } |
4552 | } | |
4553 | } | |
d41d5a01 | 4554 | |
eaf797ab TH |
4555 | if (put_cset) |
4556 | put_css_set(cset, true); | |
b4f48b63 | 4557 | } |
697f4161 | 4558 | |
bd89aabc | 4559 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 4560 | { |
f50daa70 | 4561 | if (cgroup_is_releasable(cgrp) && |
6f3d828f | 4562 | list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { |
f50daa70 LZ |
4563 | /* |
4564 | * Control Group is currently removeable. If it's not | |
81a6a5cd | 4565 | * already queued for a userspace notification, queue |
f50daa70 LZ |
4566 | * it now |
4567 | */ | |
81a6a5cd | 4568 | int need_schedule_work = 0; |
f50daa70 | 4569 | |
cdcc136f | 4570 | raw_spin_lock(&release_list_lock); |
54766d4a | 4571 | if (!cgroup_is_dead(cgrp) && |
bd89aabc PM |
4572 | list_empty(&cgrp->release_list)) { |
4573 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4574 | need_schedule_work = 1; |
4575 | } | |
cdcc136f | 4576 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4577 | if (need_schedule_work) |
4578 | schedule_work(&release_agent_work); | |
4579 | } | |
4580 | } | |
4581 | ||
81a6a5cd PM |
4582 | /* |
4583 | * Notify userspace when a cgroup is released, by running the | |
4584 | * configured release agent with the name of the cgroup (path | |
4585 | * relative to the root of cgroup file system) as the argument. | |
4586 | * | |
4587 | * Most likely, this user command will try to rmdir this cgroup. | |
4588 | * | |
4589 | * This races with the possibility that some other task will be | |
4590 | * attached to this cgroup before it is removed, or that some other | |
4591 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
4592 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
4593 | * unused, and this cgroup will be reprieved from its death sentence, | |
4594 | * to continue to serve a useful existence. Next time it's released, | |
4595 | * we will get notified again, if it still has 'notify_on_release' set. | |
4596 | * | |
4597 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
4598 | * means only wait until the task is successfully execve()'d. The | |
4599 | * separate release agent task is forked by call_usermodehelper(), | |
4600 | * then control in this thread returns here, without waiting for the | |
4601 | * release agent task. We don't bother to wait because the caller of | |
4602 | * this routine has no use for the exit status of the release agent | |
4603 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 4604 | */ |
81a6a5cd PM |
4605 | static void cgroup_release_agent(struct work_struct *work) |
4606 | { | |
4607 | BUG_ON(work != &release_agent_work); | |
4608 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 4609 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
4610 | while (!list_empty(&release_list)) { |
4611 | char *argv[3], *envp[3]; | |
4612 | int i; | |
e61734c5 | 4613 | char *pathbuf = NULL, *agentbuf = NULL, *path; |
bd89aabc | 4614 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
4615 | struct cgroup, |
4616 | release_list); | |
bd89aabc | 4617 | list_del_init(&cgrp->release_list); |
cdcc136f | 4618 | raw_spin_unlock(&release_list_lock); |
e61734c5 | 4619 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
e788e066 PM |
4620 | if (!pathbuf) |
4621 | goto continue_free; | |
e61734c5 TH |
4622 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); |
4623 | if (!path) | |
e788e066 PM |
4624 | goto continue_free; |
4625 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
4626 | if (!agentbuf) | |
4627 | goto continue_free; | |
81a6a5cd PM |
4628 | |
4629 | i = 0; | |
e788e066 | 4630 | argv[i++] = agentbuf; |
e61734c5 | 4631 | argv[i++] = path; |
81a6a5cd PM |
4632 | argv[i] = NULL; |
4633 | ||
4634 | i = 0; | |
4635 | /* minimal command environment */ | |
4636 | envp[i++] = "HOME=/"; | |
4637 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
4638 | envp[i] = NULL; | |
4639 | ||
4640 | /* Drop the lock while we invoke the usermode helper, | |
4641 | * since the exec could involve hitting disk and hence | |
4642 | * be a slow process */ | |
4643 | mutex_unlock(&cgroup_mutex); | |
4644 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 4645 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
4646 | continue_free: |
4647 | kfree(pathbuf); | |
4648 | kfree(agentbuf); | |
cdcc136f | 4649 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 4650 | } |
cdcc136f | 4651 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4652 | mutex_unlock(&cgroup_mutex); |
4653 | } | |
8bab8dde PM |
4654 | |
4655 | static int __init cgroup_disable(char *str) | |
4656 | { | |
30159ec7 | 4657 | struct cgroup_subsys *ss; |
8bab8dde | 4658 | char *token; |
30159ec7 | 4659 | int i; |
8bab8dde PM |
4660 | |
4661 | while ((token = strsep(&str, ",")) != NULL) { | |
4662 | if (!*token) | |
4663 | continue; | |
be45c900 | 4664 | |
3ed80a62 | 4665 | for_each_subsys(ss, i) { |
8bab8dde PM |
4666 | if (!strcmp(token, ss->name)) { |
4667 | ss->disabled = 1; | |
4668 | printk(KERN_INFO "Disabling %s control group" | |
4669 | " subsystem\n", ss->name); | |
4670 | break; | |
4671 | } | |
4672 | } | |
4673 | } | |
4674 | return 1; | |
4675 | } | |
4676 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 4677 | |
b77d7b60 | 4678 | /** |
5a17f543 | 4679 | * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir |
35cf0836 TH |
4680 | * @dentry: directory dentry of interest |
4681 | * @ss: subsystem of interest | |
b77d7b60 | 4682 | * |
5a17f543 TH |
4683 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
4684 | * to get the corresponding css and return it. If such css doesn't exist | |
4685 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 4686 | */ |
5a17f543 TH |
4687 | struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, |
4688 | struct cgroup_subsys *ss) | |
e5d1367f | 4689 | { |
2bd59d48 TH |
4690 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
4691 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 4692 | struct cgroup *cgrp; |
e5d1367f | 4693 | |
35cf0836 | 4694 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
4695 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
4696 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
4697 | return ERR_PTR(-EBADF); |
4698 | ||
5a17f543 TH |
4699 | rcu_read_lock(); |
4700 | ||
2bd59d48 TH |
4701 | /* |
4702 | * This path doesn't originate from kernfs and @kn could already | |
4703 | * have been or be removed at any point. @kn->priv is RCU | |
4704 | * protected for this access. See destroy_locked() for details. | |
4705 | */ | |
4706 | cgrp = rcu_dereference(kn->priv); | |
4707 | if (cgrp) | |
4708 | css = cgroup_css(cgrp, ss); | |
5a17f543 TH |
4709 | |
4710 | if (!css || !css_tryget(css)) | |
4711 | css = ERR_PTR(-ENOENT); | |
4712 | ||
4713 | rcu_read_unlock(); | |
4714 | return css; | |
e5d1367f | 4715 | } |
e5d1367f | 4716 | |
1cb650b9 LZ |
4717 | /** |
4718 | * css_from_id - lookup css by id | |
4719 | * @id: the cgroup id | |
4720 | * @ss: cgroup subsys to be looked into | |
4721 | * | |
4722 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
4723 | * Should be called under rcu_read_lock(). | |
4724 | */ | |
4725 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
4726 | { | |
4727 | struct cgroup *cgrp; | |
4728 | ||
ace2bee8 | 4729 | cgroup_assert_mutexes_or_rcu_locked(); |
1cb650b9 LZ |
4730 | |
4731 | cgrp = idr_find(&ss->root->cgroup_idr, id); | |
4732 | if (cgrp) | |
d1625964 | 4733 | return cgroup_css(cgrp, ss); |
1cb650b9 | 4734 | return NULL; |
e5d1367f SE |
4735 | } |
4736 | ||
fe693435 | 4737 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
4738 | static struct cgroup_subsys_state * |
4739 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
4740 | { |
4741 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
4742 | ||
4743 | if (!css) | |
4744 | return ERR_PTR(-ENOMEM); | |
4745 | ||
4746 | return css; | |
4747 | } | |
4748 | ||
eb95419b | 4749 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 4750 | { |
eb95419b | 4751 | kfree(css); |
fe693435 PM |
4752 | } |
4753 | ||
182446d0 TH |
4754 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
4755 | struct cftype *cft) | |
fe693435 | 4756 | { |
182446d0 | 4757 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
4758 | } |
4759 | ||
182446d0 TH |
4760 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
4761 | struct cftype *cft) | |
fe693435 PM |
4762 | { |
4763 | return (u64)(unsigned long)current->cgroups; | |
4764 | } | |
4765 | ||
182446d0 | 4766 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 4767 | struct cftype *cft) |
fe693435 PM |
4768 | { |
4769 | u64 count; | |
4770 | ||
4771 | rcu_read_lock(); | |
a8ad805c | 4772 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
4773 | rcu_read_unlock(); |
4774 | return count; | |
4775 | } | |
4776 | ||
2da8ca82 | 4777 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 4778 | { |
69d0206c | 4779 | struct cgrp_cset_link *link; |
5abb8855 | 4780 | struct css_set *cset; |
e61734c5 TH |
4781 | char *name_buf; |
4782 | ||
4783 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
4784 | if (!name_buf) | |
4785 | return -ENOMEM; | |
7717f7ba | 4786 | |
96d365e0 | 4787 | down_read(&css_set_rwsem); |
7717f7ba | 4788 | rcu_read_lock(); |
5abb8855 | 4789 | cset = rcu_dereference(current->cgroups); |
69d0206c | 4790 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 4791 | struct cgroup *c = link->cgrp; |
7717f7ba | 4792 | |
a2dd4247 | 4793 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 4794 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 4795 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
4796 | } |
4797 | rcu_read_unlock(); | |
96d365e0 | 4798 | up_read(&css_set_rwsem); |
e61734c5 | 4799 | kfree(name_buf); |
7717f7ba PM |
4800 | return 0; |
4801 | } | |
4802 | ||
4803 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 4804 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 4805 | { |
2da8ca82 | 4806 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 4807 | struct cgrp_cset_link *link; |
7717f7ba | 4808 | |
96d365e0 | 4809 | down_read(&css_set_rwsem); |
182446d0 | 4810 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 4811 | struct css_set *cset = link->cset; |
7717f7ba PM |
4812 | struct task_struct *task; |
4813 | int count = 0; | |
c7561128 | 4814 | |
5abb8855 | 4815 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 4816 | |
5abb8855 | 4817 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
4818 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
4819 | goto overflow; | |
4820 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
4821 | } | |
4822 | ||
4823 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
4824 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
4825 | goto overflow; | |
4826 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 4827 | } |
c7561128 TH |
4828 | continue; |
4829 | overflow: | |
4830 | seq_puts(seq, " ...\n"); | |
7717f7ba | 4831 | } |
96d365e0 | 4832 | up_read(&css_set_rwsem); |
7717f7ba PM |
4833 | return 0; |
4834 | } | |
4835 | ||
182446d0 | 4836 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 4837 | { |
182446d0 | 4838 | return test_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
fe693435 PM |
4839 | } |
4840 | ||
4841 | static struct cftype debug_files[] = { | |
fe693435 PM |
4842 | { |
4843 | .name = "taskcount", | |
4844 | .read_u64 = debug_taskcount_read, | |
4845 | }, | |
4846 | ||
4847 | { | |
4848 | .name = "current_css_set", | |
4849 | .read_u64 = current_css_set_read, | |
4850 | }, | |
4851 | ||
4852 | { | |
4853 | .name = "current_css_set_refcount", | |
4854 | .read_u64 = current_css_set_refcount_read, | |
4855 | }, | |
4856 | ||
7717f7ba PM |
4857 | { |
4858 | .name = "current_css_set_cg_links", | |
2da8ca82 | 4859 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
4860 | }, |
4861 | ||
4862 | { | |
4863 | .name = "cgroup_css_links", | |
2da8ca82 | 4864 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
4865 | }, |
4866 | ||
fe693435 PM |
4867 | { |
4868 | .name = "releasable", | |
4869 | .read_u64 = releasable_read, | |
4870 | }, | |
fe693435 | 4871 | |
4baf6e33 TH |
4872 | { } /* terminate */ |
4873 | }; | |
fe693435 | 4874 | |
073219e9 | 4875 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
4876 | .css_alloc = debug_css_alloc, |
4877 | .css_free = debug_css_free, | |
4baf6e33 | 4878 | .base_cftypes = debug_files, |
fe693435 PM |
4879 | }; |
4880 | #endif /* CONFIG_CGROUP_DEBUG */ |