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ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
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 | |
ddbcc7e8 | 211 | /* convenient tests for these bits */ |
54766d4a | 212 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 213 | { |
54766d4a | 214 | return test_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 PM |
215 | } |
216 | ||
59f5296b TH |
217 | struct cgroup_subsys_state *seq_css(struct seq_file *seq) |
218 | { | |
2bd59d48 TH |
219 | struct kernfs_open_file *of = seq->private; |
220 | struct cgroup *cgrp = of->kn->parent->priv; | |
221 | struct cftype *cft = seq_cft(seq); | |
222 | ||
223 | /* | |
224 | * This is open and unprotected implementation of cgroup_css(). | |
225 | * seq_css() is only called from a kernfs file operation which has | |
226 | * an active reference on the file. Because all the subsystem | |
227 | * files are drained before a css is disassociated with a cgroup, | |
228 | * the matching css from the cgroup's subsys table is guaranteed to | |
229 | * be and stay valid until the enclosing operation is complete. | |
230 | */ | |
231 | if (cft->ss) | |
232 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
233 | else | |
234 | return &cgrp->dummy_css; | |
59f5296b TH |
235 | } |
236 | EXPORT_SYMBOL_GPL(seq_css); | |
237 | ||
78574cf9 LZ |
238 | /** |
239 | * cgroup_is_descendant - test ancestry | |
240 | * @cgrp: the cgroup to be tested | |
241 | * @ancestor: possible ancestor of @cgrp | |
242 | * | |
243 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
244 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
245 | * and @ancestor are accessible. | |
246 | */ | |
247 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
248 | { | |
249 | while (cgrp) { | |
250 | if (cgrp == ancestor) | |
251 | return true; | |
252 | cgrp = cgrp->parent; | |
253 | } | |
254 | return false; | |
255 | } | |
ddbcc7e8 | 256 | |
e9685a03 | 257 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
258 | { |
259 | const int bits = | |
bd89aabc PM |
260 | (1 << CGRP_RELEASABLE) | |
261 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
262 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
263 | } |
264 | ||
e9685a03 | 265 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 266 | { |
bd89aabc | 267 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
268 | } |
269 | ||
1c6727af TH |
270 | /** |
271 | * for_each_css - iterate all css's of a cgroup | |
272 | * @css: the iteration cursor | |
273 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
274 | * @cgrp: the target cgroup to iterate css's of | |
275 | * | |
276 | * Should be called under cgroup_mutex. | |
277 | */ | |
278 | #define for_each_css(css, ssid, cgrp) \ | |
279 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
280 | if (!((css) = rcu_dereference_check( \ | |
281 | (cgrp)->subsys[(ssid)], \ | |
ace2bee8 | 282 | lockdep_is_held(&cgroup_tree_mutex) || \ |
1c6727af TH |
283 | lockdep_is_held(&cgroup_mutex)))) { } \ |
284 | else | |
285 | ||
30159ec7 | 286 | /** |
3ed80a62 | 287 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 288 | * @ss: the iteration cursor |
780cd8b3 | 289 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 290 | */ |
780cd8b3 | 291 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
292 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
293 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 294 | |
985ed670 TH |
295 | /* iterate across the hierarchies */ |
296 | #define for_each_root(root) \ | |
5549c497 | 297 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 298 | |
7ae1bad9 TH |
299 | /** |
300 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
301 | * @cgrp: the cgroup to be checked for liveness | |
302 | * | |
47cfcd09 TH |
303 | * On success, returns true; the mutex should be later unlocked. On |
304 | * failure returns false with no lock held. | |
7ae1bad9 | 305 | */ |
b9777cf8 | 306 | static bool cgroup_lock_live_group(struct cgroup *cgrp) |
7ae1bad9 TH |
307 | { |
308 | mutex_lock(&cgroup_mutex); | |
54766d4a | 309 | if (cgroup_is_dead(cgrp)) { |
7ae1bad9 TH |
310 | mutex_unlock(&cgroup_mutex); |
311 | return false; | |
312 | } | |
313 | return true; | |
314 | } | |
7ae1bad9 | 315 | |
81a6a5cd PM |
316 | /* the list of cgroups eligible for automatic release. Protected by |
317 | * release_list_lock */ | |
318 | static LIST_HEAD(release_list); | |
cdcc136f | 319 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
320 | static void cgroup_release_agent(struct work_struct *work); |
321 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 322 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 323 | |
69d0206c TH |
324 | /* |
325 | * A cgroup can be associated with multiple css_sets as different tasks may | |
326 | * belong to different cgroups on different hierarchies. In the other | |
327 | * direction, a css_set is naturally associated with multiple cgroups. | |
328 | * This M:N relationship is represented by the following link structure | |
329 | * which exists for each association and allows traversing the associations | |
330 | * from both sides. | |
331 | */ | |
332 | struct cgrp_cset_link { | |
333 | /* the cgroup and css_set this link associates */ | |
334 | struct cgroup *cgrp; | |
335 | struct css_set *cset; | |
336 | ||
337 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
338 | struct list_head cset_link; | |
339 | ||
340 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
341 | struct list_head cgrp_link; | |
817929ec PM |
342 | }; |
343 | ||
172a2c06 TH |
344 | /* |
345 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
346 | * hierarchies being mounted. It contains a pointer to the root state |
347 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
348 | * reference-counted, to improve performance when child cgroups | |
349 | * haven't been created. | |
350 | */ | |
172a2c06 TH |
351 | static struct css_set init_css_set = { |
352 | .refcount = ATOMIC_INIT(1), | |
353 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
354 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
355 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
356 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
357 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
358 | }; | |
817929ec | 359 | |
172a2c06 | 360 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 361 | |
7717f7ba PM |
362 | /* |
363 | * hash table for cgroup groups. This improves the performance to find | |
364 | * an existing css_set. This hash doesn't (currently) take into | |
365 | * account cgroups in empty hierarchies. | |
366 | */ | |
472b1053 | 367 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 368 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 369 | |
0ac801fe | 370 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 371 | { |
0ac801fe | 372 | unsigned long key = 0UL; |
30159ec7 TH |
373 | struct cgroup_subsys *ss; |
374 | int i; | |
472b1053 | 375 | |
30159ec7 | 376 | for_each_subsys(ss, i) |
0ac801fe LZ |
377 | key += (unsigned long)css[i]; |
378 | key = (key >> 16) ^ key; | |
472b1053 | 379 | |
0ac801fe | 380 | return key; |
472b1053 LZ |
381 | } |
382 | ||
89c5509b | 383 | static void put_css_set_locked(struct css_set *cset, bool taskexit) |
b4f48b63 | 384 | { |
69d0206c | 385 | struct cgrp_cset_link *link, *tmp_link; |
5abb8855 | 386 | |
89c5509b TH |
387 | lockdep_assert_held(&css_set_rwsem); |
388 | ||
389 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 390 | return; |
81a6a5cd | 391 | |
2c6ab6d2 | 392 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
5abb8855 | 393 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
394 | css_set_count--; |
395 | ||
69d0206c | 396 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 397 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 398 | |
69d0206c TH |
399 | list_del(&link->cset_link); |
400 | list_del(&link->cgrp_link); | |
71b5707e | 401 | |
96d365e0 | 402 | /* @cgrp can't go away while we're holding css_set_rwsem */ |
6f3d828f | 403 | if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { |
81a6a5cd | 404 | if (taskexit) |
bd89aabc PM |
405 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
406 | check_for_release(cgrp); | |
81a6a5cd | 407 | } |
2c6ab6d2 PM |
408 | |
409 | kfree(link); | |
81a6a5cd | 410 | } |
2c6ab6d2 | 411 | |
5abb8855 | 412 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
413 | } |
414 | ||
89c5509b TH |
415 | static void put_css_set(struct css_set *cset, bool taskexit) |
416 | { | |
417 | /* | |
418 | * Ensure that the refcount doesn't hit zero while any readers | |
419 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
420 | * rwlock | |
421 | */ | |
422 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
423 | return; | |
424 | ||
425 | down_write(&css_set_rwsem); | |
426 | put_css_set_locked(cset, taskexit); | |
427 | up_write(&css_set_rwsem); | |
428 | } | |
429 | ||
817929ec PM |
430 | /* |
431 | * refcounted get/put for css_set objects | |
432 | */ | |
5abb8855 | 433 | static inline void get_css_set(struct css_set *cset) |
817929ec | 434 | { |
5abb8855 | 435 | atomic_inc(&cset->refcount); |
817929ec PM |
436 | } |
437 | ||
b326f9d0 | 438 | /** |
7717f7ba | 439 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
440 | * @cset: candidate css_set being tested |
441 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
442 | * @new_cgrp: cgroup that's being entered by the task |
443 | * @template: desired set of css pointers in css_set (pre-calculated) | |
444 | * | |
6f4b7e63 | 445 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
446 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
447 | */ | |
5abb8855 TH |
448 | static bool compare_css_sets(struct css_set *cset, |
449 | struct css_set *old_cset, | |
7717f7ba PM |
450 | struct cgroup *new_cgrp, |
451 | struct cgroup_subsys_state *template[]) | |
452 | { | |
453 | struct list_head *l1, *l2; | |
454 | ||
5abb8855 | 455 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) { |
7717f7ba PM |
456 | /* Not all subsystems matched */ |
457 | return false; | |
458 | } | |
459 | ||
460 | /* | |
461 | * Compare cgroup pointers in order to distinguish between | |
462 | * different cgroups in heirarchies with no subsystems. We | |
463 | * could get by with just this check alone (and skip the | |
464 | * memcmp above) but on most setups the memcmp check will | |
465 | * avoid the need for this more expensive check on almost all | |
466 | * candidates. | |
467 | */ | |
468 | ||
69d0206c TH |
469 | l1 = &cset->cgrp_links; |
470 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 471 | while (1) { |
69d0206c | 472 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 473 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
474 | |
475 | l1 = l1->next; | |
476 | l2 = l2->next; | |
477 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
478 | if (l1 == &cset->cgrp_links) { |
479 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
480 | break; |
481 | } else { | |
69d0206c | 482 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
483 | } |
484 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
485 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
486 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
487 | cgrp1 = link1->cgrp; | |
488 | cgrp2 = link2->cgrp; | |
7717f7ba | 489 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 490 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
491 | |
492 | /* | |
493 | * If this hierarchy is the hierarchy of the cgroup | |
494 | * that's changing, then we need to check that this | |
495 | * css_set points to the new cgroup; if it's any other | |
496 | * hierarchy, then this css_set should point to the | |
497 | * same cgroup as the old css_set. | |
498 | */ | |
5abb8855 TH |
499 | if (cgrp1->root == new_cgrp->root) { |
500 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
501 | return false; |
502 | } else { | |
5abb8855 | 503 | if (cgrp1 != cgrp2) |
7717f7ba PM |
504 | return false; |
505 | } | |
506 | } | |
507 | return true; | |
508 | } | |
509 | ||
b326f9d0 TH |
510 | /** |
511 | * find_existing_css_set - init css array and find the matching css_set | |
512 | * @old_cset: the css_set that we're using before the cgroup transition | |
513 | * @cgrp: the cgroup that we're moving into | |
514 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 515 | */ |
5abb8855 TH |
516 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
517 | struct cgroup *cgrp, | |
518 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 519 | { |
3dd06ffa | 520 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 521 | struct cgroup_subsys *ss; |
5abb8855 | 522 | struct css_set *cset; |
0ac801fe | 523 | unsigned long key; |
b326f9d0 | 524 | int i; |
817929ec | 525 | |
aae8aab4 BB |
526 | /* |
527 | * Build the set of subsystem state objects that we want to see in the | |
528 | * new css_set. while subsystems can change globally, the entries here | |
529 | * won't change, so no need for locking. | |
530 | */ | |
30159ec7 | 531 | for_each_subsys(ss, i) { |
3dd06ffa | 532 | if (root->cgrp.subsys_mask & (1UL << i)) { |
817929ec PM |
533 | /* Subsystem is in this hierarchy. So we want |
534 | * the subsystem state from the new | |
535 | * cgroup */ | |
ca8bdcaf | 536 | template[i] = cgroup_css(cgrp, ss); |
817929ec PM |
537 | } else { |
538 | /* Subsystem is not in this hierarchy, so we | |
539 | * don't want to change the subsystem state */ | |
5abb8855 | 540 | template[i] = old_cset->subsys[i]; |
817929ec PM |
541 | } |
542 | } | |
543 | ||
0ac801fe | 544 | key = css_set_hash(template); |
5abb8855 TH |
545 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
546 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
547 | continue; |
548 | ||
549 | /* This css_set matches what we need */ | |
5abb8855 | 550 | return cset; |
472b1053 | 551 | } |
817929ec PM |
552 | |
553 | /* No existing cgroup group matched */ | |
554 | return NULL; | |
555 | } | |
556 | ||
69d0206c | 557 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 558 | { |
69d0206c | 559 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 560 | |
69d0206c TH |
561 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
562 | list_del(&link->cset_link); | |
36553434 LZ |
563 | kfree(link); |
564 | } | |
565 | } | |
566 | ||
69d0206c TH |
567 | /** |
568 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
569 | * @count: the number of links to allocate | |
570 | * @tmp_links: list_head the allocated links are put on | |
571 | * | |
572 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
573 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 574 | */ |
69d0206c | 575 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 576 | { |
69d0206c | 577 | struct cgrp_cset_link *link; |
817929ec | 578 | int i; |
69d0206c TH |
579 | |
580 | INIT_LIST_HEAD(tmp_links); | |
581 | ||
817929ec | 582 | for (i = 0; i < count; i++) { |
f4f4be2b | 583 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 584 | if (!link) { |
69d0206c | 585 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
586 | return -ENOMEM; |
587 | } | |
69d0206c | 588 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
589 | } |
590 | return 0; | |
591 | } | |
592 | ||
c12f65d4 LZ |
593 | /** |
594 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 595 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 596 | * @cset: the css_set to be linked |
c12f65d4 LZ |
597 | * @cgrp: the destination cgroup |
598 | */ | |
69d0206c TH |
599 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
600 | struct cgroup *cgrp) | |
c12f65d4 | 601 | { |
69d0206c | 602 | struct cgrp_cset_link *link; |
c12f65d4 | 603 | |
69d0206c TH |
604 | BUG_ON(list_empty(tmp_links)); |
605 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); | |
606 | link->cset = cset; | |
7717f7ba | 607 | link->cgrp = cgrp; |
69d0206c | 608 | list_move(&link->cset_link, &cgrp->cset_links); |
7717f7ba PM |
609 | /* |
610 | * Always add links to the tail of the list so that the list | |
611 | * is sorted by order of hierarchy creation | |
612 | */ | |
69d0206c | 613 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
614 | } |
615 | ||
b326f9d0 TH |
616 | /** |
617 | * find_css_set - return a new css_set with one cgroup updated | |
618 | * @old_cset: the baseline css_set | |
619 | * @cgrp: the cgroup to be updated | |
620 | * | |
621 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
622 | * substituted into the appropriate hierarchy. | |
817929ec | 623 | */ |
5abb8855 TH |
624 | static struct css_set *find_css_set(struct css_set *old_cset, |
625 | struct cgroup *cgrp) | |
817929ec | 626 | { |
b326f9d0 | 627 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 628 | struct css_set *cset; |
69d0206c TH |
629 | struct list_head tmp_links; |
630 | struct cgrp_cset_link *link; | |
0ac801fe | 631 | unsigned long key; |
472b1053 | 632 | |
b326f9d0 TH |
633 | lockdep_assert_held(&cgroup_mutex); |
634 | ||
817929ec PM |
635 | /* First see if we already have a cgroup group that matches |
636 | * the desired set */ | |
96d365e0 | 637 | down_read(&css_set_rwsem); |
5abb8855 TH |
638 | cset = find_existing_css_set(old_cset, cgrp, template); |
639 | if (cset) | |
640 | get_css_set(cset); | |
96d365e0 | 641 | up_read(&css_set_rwsem); |
817929ec | 642 | |
5abb8855 TH |
643 | if (cset) |
644 | return cset; | |
817929ec | 645 | |
f4f4be2b | 646 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 647 | if (!cset) |
817929ec PM |
648 | return NULL; |
649 | ||
69d0206c | 650 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 651 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 652 | kfree(cset); |
817929ec PM |
653 | return NULL; |
654 | } | |
655 | ||
5abb8855 | 656 | atomic_set(&cset->refcount, 1); |
69d0206c | 657 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 658 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 659 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 660 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 661 | INIT_LIST_HEAD(&cset->mg_node); |
5abb8855 | 662 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
663 | |
664 | /* Copy the set of subsystem state objects generated in | |
665 | * find_existing_css_set() */ | |
5abb8855 | 666 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 667 | |
96d365e0 | 668 | down_write(&css_set_rwsem); |
817929ec | 669 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 670 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 671 | struct cgroup *c = link->cgrp; |
69d0206c | 672 | |
7717f7ba PM |
673 | if (c->root == cgrp->root) |
674 | c = cgrp; | |
69d0206c | 675 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 676 | } |
817929ec | 677 | |
69d0206c | 678 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 679 | |
817929ec | 680 | css_set_count++; |
472b1053 LZ |
681 | |
682 | /* Add this cgroup group to the hash table */ | |
5abb8855 TH |
683 | key = css_set_hash(cset->subsys); |
684 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 685 | |
96d365e0 | 686 | up_write(&css_set_rwsem); |
817929ec | 687 | |
5abb8855 | 688 | return cset; |
b4f48b63 PM |
689 | } |
690 | ||
3dd06ffa | 691 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 692 | { |
3dd06ffa | 693 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 694 | |
3dd06ffa | 695 | return root_cgrp->root; |
2bd59d48 TH |
696 | } |
697 | ||
3dd06ffa | 698 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
699 | { |
700 | int id; | |
701 | ||
702 | lockdep_assert_held(&cgroup_mutex); | |
703 | ||
985ed670 | 704 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
705 | if (id < 0) |
706 | return id; | |
707 | ||
708 | root->hierarchy_id = id; | |
709 | return 0; | |
710 | } | |
711 | ||
3dd06ffa | 712 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
713 | { |
714 | lockdep_assert_held(&cgroup_mutex); | |
715 | ||
716 | if (root->hierarchy_id) { | |
717 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
718 | root->hierarchy_id = 0; | |
719 | } | |
720 | } | |
721 | ||
3dd06ffa | 722 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
723 | { |
724 | if (root) { | |
725 | /* hierarhcy ID shoulid already have been released */ | |
726 | WARN_ON_ONCE(root->hierarchy_id); | |
727 | ||
728 | idr_destroy(&root->cgroup_idr); | |
729 | kfree(root); | |
730 | } | |
731 | } | |
732 | ||
3dd06ffa | 733 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 734 | { |
3dd06ffa | 735 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 736 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 737 | |
2bd59d48 | 738 | mutex_lock(&cgroup_tree_mutex); |
2bd59d48 | 739 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 740 | |
776f02fa | 741 | BUG_ON(atomic_read(&root->nr_cgrps)); |
f2e85d57 TH |
742 | BUG_ON(!list_empty(&cgrp->children)); |
743 | ||
f2e85d57 | 744 | /* Rebind all subsystems back to the default hierarchy */ |
3dd06ffa | 745 | rebind_subsystems(&cgrp_dfl_root, cgrp->subsys_mask); |
7717f7ba | 746 | |
7717f7ba | 747 | /* |
f2e85d57 TH |
748 | * Release all the links from cset_links to this hierarchy's |
749 | * root cgroup | |
7717f7ba | 750 | */ |
96d365e0 | 751 | down_write(&css_set_rwsem); |
f2e85d57 TH |
752 | |
753 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
754 | list_del(&link->cset_link); | |
755 | list_del(&link->cgrp_link); | |
756 | kfree(link); | |
757 | } | |
96d365e0 | 758 | up_write(&css_set_rwsem); |
f2e85d57 TH |
759 | |
760 | if (!list_empty(&root->root_list)) { | |
761 | list_del(&root->root_list); | |
762 | cgroup_root_count--; | |
763 | } | |
764 | ||
765 | cgroup_exit_root_id(root); | |
766 | ||
767 | mutex_unlock(&cgroup_mutex); | |
768 | mutex_unlock(&cgroup_tree_mutex); | |
f2e85d57 | 769 | |
2bd59d48 | 770 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
771 | cgroup_free_root(root); |
772 | } | |
773 | ||
ceb6a081 TH |
774 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
775 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 776 | struct cgroup_root *root) |
7717f7ba | 777 | { |
7717f7ba PM |
778 | struct cgroup *res = NULL; |
779 | ||
96d365e0 TH |
780 | lockdep_assert_held(&cgroup_mutex); |
781 | lockdep_assert_held(&css_set_rwsem); | |
782 | ||
5abb8855 | 783 | if (cset == &init_css_set) { |
3dd06ffa | 784 | res = &root->cgrp; |
7717f7ba | 785 | } else { |
69d0206c TH |
786 | struct cgrp_cset_link *link; |
787 | ||
788 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 789 | struct cgroup *c = link->cgrp; |
69d0206c | 790 | |
7717f7ba PM |
791 | if (c->root == root) { |
792 | res = c; | |
793 | break; | |
794 | } | |
795 | } | |
796 | } | |
96d365e0 | 797 | |
7717f7ba PM |
798 | BUG_ON(!res); |
799 | return res; | |
800 | } | |
801 | ||
ddbcc7e8 | 802 | /* |
ceb6a081 TH |
803 | * Return the cgroup for "task" from the given hierarchy. Must be |
804 | * called with cgroup_mutex and css_set_rwsem held. | |
805 | */ | |
806 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 807 | struct cgroup_root *root) |
ceb6a081 TH |
808 | { |
809 | /* | |
810 | * No need to lock the task - since we hold cgroup_mutex the | |
811 | * task can't change groups, so the only thing that can happen | |
812 | * is that it exits and its css is set back to init_css_set. | |
813 | */ | |
814 | return cset_cgroup_from_root(task_css_set(task), root); | |
815 | } | |
816 | ||
ddbcc7e8 | 817 | /* |
ddbcc7e8 PM |
818 | * A task must hold cgroup_mutex to modify cgroups. |
819 | * | |
820 | * Any task can increment and decrement the count field without lock. | |
821 | * So in general, code holding cgroup_mutex can't rely on the count | |
822 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 823 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
824 | * means that no tasks are currently attached, therefore there is no |
825 | * way a task attached to that cgroup can fork (the other way to | |
826 | * increment the count). So code holding cgroup_mutex can safely | |
827 | * assume that if the count is zero, it will stay zero. Similarly, if | |
828 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
829 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
830 | * needs that mutex. | |
831 | * | |
ddbcc7e8 PM |
832 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
833 | * (usually) take cgroup_mutex. These are the two most performance | |
834 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
835 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
836 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
837 | * to the release agent with the name of the cgroup (path relative to |
838 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
839 | * |
840 | * A cgroup can only be deleted if both its 'count' of using tasks | |
841 | * is zero, and its list of 'children' cgroups is empty. Since all | |
842 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 843 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 844 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 845 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
846 | * |
847 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 848 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
849 | */ |
850 | ||
628f7cd4 | 851 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); |
2bd59d48 | 852 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 853 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 854 | |
8d7e6fb0 TH |
855 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
856 | char *buf) | |
ddbcc7e8 | 857 | { |
8d7e6fb0 TH |
858 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
859 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
860 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
861 | cft->ss->name, cft->name); | |
862 | else | |
863 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
864 | return buf; | |
ddbcc7e8 PM |
865 | } |
866 | ||
f2e85d57 TH |
867 | /** |
868 | * cgroup_file_mode - deduce file mode of a control file | |
869 | * @cft: the control file in question | |
870 | * | |
871 | * returns cft->mode if ->mode is not 0 | |
872 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
873 | * returns S_IRUGO if it has only a read handler | |
874 | * returns S_IWUSR if it has only a write hander | |
875 | */ | |
876 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 877 | { |
f2e85d57 | 878 | umode_t mode = 0; |
65dff759 | 879 | |
f2e85d57 TH |
880 | if (cft->mode) |
881 | return cft->mode; | |
882 | ||
883 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) | |
884 | mode |= S_IRUGO; | |
885 | ||
886 | if (cft->write_u64 || cft->write_s64 || cft->write_string || | |
887 | cft->trigger) | |
888 | mode |= S_IWUSR; | |
889 | ||
890 | return mode; | |
65dff759 LZ |
891 | } |
892 | ||
be445626 LZ |
893 | static void cgroup_free_fn(struct work_struct *work) |
894 | { | |
ea15f8cc | 895 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); |
be445626 | 896 | |
3c9c825b | 897 | atomic_dec(&cgrp->root->nr_cgrps); |
b1a21367 | 898 | cgroup_pidlist_destroy_all(cgrp); |
be445626 | 899 | |
776f02fa TH |
900 | if (cgrp->parent) { |
901 | /* | |
902 | * We get a ref to the parent, and put the ref when this | |
903 | * cgroup is being freed, so it's guaranteed that the | |
904 | * parent won't be destroyed before its children. | |
905 | */ | |
906 | cgroup_put(cgrp->parent); | |
907 | kernfs_put(cgrp->kn); | |
908 | kfree(cgrp); | |
909 | } else { | |
910 | /* | |
3dd06ffa | 911 | * This is root cgroup's refcnt reaching zero, which |
776f02fa TH |
912 | * indicates that the root should be released. |
913 | */ | |
914 | cgroup_destroy_root(cgrp->root); | |
915 | } | |
be445626 LZ |
916 | } |
917 | ||
918 | static void cgroup_free_rcu(struct rcu_head *head) | |
919 | { | |
920 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); | |
921 | ||
ea15f8cc | 922 | INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); |
e5fca243 | 923 | queue_work(cgroup_destroy_wq, &cgrp->destroy_work); |
be445626 LZ |
924 | } |
925 | ||
59f5296b | 926 | static void cgroup_get(struct cgroup *cgrp) |
ddbcc7e8 | 927 | { |
2bd59d48 TH |
928 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
929 | WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0); | |
930 | atomic_inc(&cgrp->refcnt); | |
ddbcc7e8 PM |
931 | } |
932 | ||
59f5296b | 933 | static void cgroup_put(struct cgroup *cgrp) |
05ef1d7c | 934 | { |
2bd59d48 TH |
935 | if (!atomic_dec_and_test(&cgrp->refcnt)) |
936 | return; | |
776f02fa | 937 | if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp))) |
2bd59d48 | 938 | return; |
05ef1d7c | 939 | |
2739d3cc | 940 | /* |
2bd59d48 TH |
941 | * XXX: cgrp->id is only used to look up css's. As cgroup and |
942 | * css's lifetimes will be decoupled, it should be made | |
943 | * per-subsystem and moved to css->id so that lookups are | |
944 | * successful until the target css is released. | |
2739d3cc | 945 | */ |
2bd59d48 TH |
946 | mutex_lock(&cgroup_mutex); |
947 | idr_remove(&cgrp->root->cgroup_idr, cgrp->id); | |
948 | mutex_unlock(&cgroup_mutex); | |
949 | cgrp->id = -1; | |
05ef1d7c | 950 | |
2bd59d48 | 951 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
ddbcc7e8 | 952 | } |
05ef1d7c | 953 | |
2739d3cc | 954 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 955 | { |
2bd59d48 | 956 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 957 | |
ace2bee8 | 958 | lockdep_assert_held(&cgroup_tree_mutex); |
2bd59d48 | 959 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
960 | } |
961 | ||
13af07df | 962 | /** |
628f7cd4 | 963 | * cgroup_clear_dir - remove subsys files in a cgroup directory |
8f89140a | 964 | * @cgrp: target cgroup |
13af07df AR |
965 | * @subsys_mask: mask of the subsystem ids whose files should be removed |
966 | */ | |
628f7cd4 | 967 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
05ef1d7c | 968 | { |
13af07df | 969 | struct cgroup_subsys *ss; |
b420ba7d | 970 | int i; |
05ef1d7c | 971 | |
b420ba7d | 972 | for_each_subsys(ss, i) { |
0adb0704 | 973 | struct cftype *cfts; |
b420ba7d TH |
974 | |
975 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 976 | continue; |
0adb0704 TH |
977 | list_for_each_entry(cfts, &ss->cfts, node) |
978 | cgroup_addrm_files(cgrp, cfts, false); | |
13af07df | 979 | } |
ddbcc7e8 PM |
980 | } |
981 | ||
3dd06ffa | 982 | static int rebind_subsystems(struct cgroup_root *dst_root, |
5df36032 | 983 | unsigned long ss_mask) |
ddbcc7e8 | 984 | { |
30159ec7 | 985 | struct cgroup_subsys *ss; |
5df36032 | 986 | int ssid, ret; |
ddbcc7e8 | 987 | |
ace2bee8 TH |
988 | lockdep_assert_held(&cgroup_tree_mutex); |
989 | lockdep_assert_held(&cgroup_mutex); | |
ddbcc7e8 | 990 | |
5df36032 TH |
991 | for_each_subsys(ss, ssid) { |
992 | if (!(ss_mask & (1 << ssid))) | |
993 | continue; | |
aae8aab4 | 994 | |
5df36032 | 995 | /* if @ss is on the dummy_root, we can always move it */ |
3dd06ffa | 996 | if (ss->root == &cgrp_dfl_root) |
ddbcc7e8 | 997 | continue; |
30159ec7 | 998 | |
5df36032 | 999 | /* if @ss has non-root cgroups attached to it, can't move */ |
3dd06ffa | 1000 | if (!list_empty(&ss->root->cgrp.children)) |
3ed80a62 | 1001 | return -EBUSY; |
1d5be6b2 | 1002 | |
5df36032 | 1003 | /* can't move between two non-dummy roots either */ |
3dd06ffa | 1004 | if (dst_root != &cgrp_dfl_root) |
5df36032 | 1005 | return -EBUSY; |
ddbcc7e8 PM |
1006 | } |
1007 | ||
a2dd4247 TH |
1008 | ret = cgroup_populate_dir(&dst_root->cgrp, ss_mask); |
1009 | if (ret) { | |
1010 | if (dst_root != &cgrp_dfl_root) | |
5df36032 | 1011 | return ret; |
ddbcc7e8 | 1012 | |
a2dd4247 TH |
1013 | /* |
1014 | * Rebinding back to the default root is not allowed to | |
1015 | * fail. Using both default and non-default roots should | |
1016 | * be rare. Moving subsystems back and forth even more so. | |
1017 | * Just warn about it and continue. | |
1018 | */ | |
1019 | if (cgrp_dfl_root_visible) { | |
1020 | pr_warning("cgroup: failed to create files (%d) while rebinding 0x%lx to default root\n", | |
1021 | ret, ss_mask); | |
1022 | pr_warning("cgroup: you may retry by moving them to a different hierarchy and unbinding\n"); | |
1023 | } | |
5df36032 | 1024 | } |
3126121f TH |
1025 | |
1026 | /* | |
1027 | * Nothing can fail from this point on. Remove files for the | |
1028 | * removed subsystems and rebind each subsystem. | |
1029 | */ | |
4ac06017 | 1030 | mutex_unlock(&cgroup_mutex); |
5df36032 | 1031 | for_each_subsys(ss, ssid) |
a2dd4247 | 1032 | if (ss_mask & (1 << ssid)) |
3dd06ffa | 1033 | cgroup_clear_dir(&ss->root->cgrp, 1 << ssid); |
4ac06017 | 1034 | mutex_lock(&cgroup_mutex); |
a8a648c4 | 1035 | |
5df36032 | 1036 | for_each_subsys(ss, ssid) { |
3dd06ffa | 1037 | struct cgroup_root *src_root; |
5df36032 | 1038 | struct cgroup_subsys_state *css; |
a8a648c4 | 1039 | |
5df36032 TH |
1040 | if (!(ss_mask & (1 << ssid))) |
1041 | continue; | |
a8a648c4 | 1042 | |
5df36032 | 1043 | src_root = ss->root; |
3dd06ffa | 1044 | css = cgroup_css(&src_root->cgrp, ss); |
a8a648c4 | 1045 | |
3dd06ffa | 1046 | WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss)); |
73e80ed8 | 1047 | |
3dd06ffa TH |
1048 | RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL); |
1049 | rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css); | |
5df36032 | 1050 | ss->root = dst_root; |
3dd06ffa | 1051 | css->cgroup = &dst_root->cgrp; |
73e80ed8 | 1052 | |
3dd06ffa TH |
1053 | src_root->cgrp.subsys_mask &= ~(1 << ssid); |
1054 | dst_root->cgrp.subsys_mask |= 1 << ssid; | |
a8a648c4 | 1055 | |
5df36032 TH |
1056 | if (ss->bind) |
1057 | ss->bind(css); | |
ddbcc7e8 | 1058 | } |
ddbcc7e8 | 1059 | |
a2dd4247 | 1060 | kernfs_activate(dst_root->cgrp.kn); |
ddbcc7e8 PM |
1061 | return 0; |
1062 | } | |
1063 | ||
2bd59d48 TH |
1064 | static int cgroup_show_options(struct seq_file *seq, |
1065 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1066 | { |
3dd06ffa | 1067 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1068 | struct cgroup_subsys *ss; |
b85d2040 | 1069 | int ssid; |
ddbcc7e8 | 1070 | |
b85d2040 | 1071 | for_each_subsys(ss, ssid) |
3dd06ffa | 1072 | if (root->cgrp.subsys_mask & (1 << ssid)) |
b85d2040 | 1073 | seq_printf(seq, ",%s", ss->name); |
873fe09e TH |
1074 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) |
1075 | seq_puts(seq, ",sane_behavior"); | |
93438629 | 1076 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1077 | seq_puts(seq, ",noprefix"); |
93438629 | 1078 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1079 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1080 | |
1081 | spin_lock(&release_agent_path_lock); | |
81a6a5cd PM |
1082 | if (strlen(root->release_agent_path)) |
1083 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
69e943b7 TH |
1084 | spin_unlock(&release_agent_path_lock); |
1085 | ||
3dd06ffa | 1086 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1087 | seq_puts(seq, ",clone_children"); |
c6d57f33 PM |
1088 | if (strlen(root->name)) |
1089 | seq_printf(seq, ",name=%s", root->name); | |
ddbcc7e8 PM |
1090 | return 0; |
1091 | } | |
1092 | ||
1093 | struct cgroup_sb_opts { | |
a1a71b45 | 1094 | unsigned long subsys_mask; |
ddbcc7e8 | 1095 | unsigned long flags; |
81a6a5cd | 1096 | char *release_agent; |
2260e7fc | 1097 | bool cpuset_clone_children; |
c6d57f33 | 1098 | char *name; |
2c6ab6d2 PM |
1099 | /* User explicitly requested empty subsystem */ |
1100 | bool none; | |
ddbcc7e8 PM |
1101 | }; |
1102 | ||
aae8aab4 | 1103 | /* |
9871bf95 TH |
1104 | * Convert a hierarchy specifier into a bitmask of subsystems and |
1105 | * flags. Call with cgroup_mutex held to protect the cgroup_subsys[] | |
1106 | * array. This function takes refcounts on subsystems to be used, unless it | |
1107 | * returns error, in which case no refcounts are taken. | |
aae8aab4 | 1108 | */ |
cf5d5941 | 1109 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1110 | { |
32a8cf23 DL |
1111 | char *token, *o = data; |
1112 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1113 | unsigned long mask = (unsigned long)-1; |
30159ec7 TH |
1114 | struct cgroup_subsys *ss; |
1115 | int i; | |
f9ab5b5b | 1116 | |
aae8aab4 BB |
1117 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1118 | ||
f9ab5b5b | 1119 | #ifdef CONFIG_CPUSETS |
073219e9 | 1120 | mask = ~(1UL << cpuset_cgrp_id); |
f9ab5b5b | 1121 | #endif |
ddbcc7e8 | 1122 | |
c6d57f33 | 1123 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1124 | |
1125 | while ((token = strsep(&o, ",")) != NULL) { | |
1126 | if (!*token) | |
1127 | return -EINVAL; | |
32a8cf23 | 1128 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1129 | /* Explicitly have no subsystems */ |
1130 | opts->none = true; | |
32a8cf23 DL |
1131 | continue; |
1132 | } | |
1133 | if (!strcmp(token, "all")) { | |
1134 | /* Mutually exclusive option 'all' + subsystem name */ | |
1135 | if (one_ss) | |
1136 | return -EINVAL; | |
1137 | all_ss = true; | |
1138 | continue; | |
1139 | } | |
873fe09e TH |
1140 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1141 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1142 | continue; | |
1143 | } | |
32a8cf23 | 1144 | if (!strcmp(token, "noprefix")) { |
93438629 | 1145 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1146 | continue; |
1147 | } | |
1148 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1149 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1150 | continue; |
1151 | } | |
03b1cde6 | 1152 | if (!strcmp(token, "xattr")) { |
93438629 | 1153 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1154 | continue; |
1155 | } | |
32a8cf23 | 1156 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1157 | /* Specifying two release agents is forbidden */ |
1158 | if (opts->release_agent) | |
1159 | return -EINVAL; | |
c6d57f33 | 1160 | opts->release_agent = |
e400c285 | 1161 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1162 | if (!opts->release_agent) |
1163 | return -ENOMEM; | |
32a8cf23 DL |
1164 | continue; |
1165 | } | |
1166 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1167 | const char *name = token + 5; |
1168 | /* Can't specify an empty name */ | |
1169 | if (!strlen(name)) | |
1170 | return -EINVAL; | |
1171 | /* Must match [\w.-]+ */ | |
1172 | for (i = 0; i < strlen(name); i++) { | |
1173 | char c = name[i]; | |
1174 | if (isalnum(c)) | |
1175 | continue; | |
1176 | if ((c == '.') || (c == '-') || (c == '_')) | |
1177 | continue; | |
1178 | return -EINVAL; | |
1179 | } | |
1180 | /* Specifying two names is forbidden */ | |
1181 | if (opts->name) | |
1182 | return -EINVAL; | |
1183 | opts->name = kstrndup(name, | |
e400c285 | 1184 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1185 | GFP_KERNEL); |
1186 | if (!opts->name) | |
1187 | return -ENOMEM; | |
32a8cf23 DL |
1188 | |
1189 | continue; | |
1190 | } | |
1191 | ||
30159ec7 | 1192 | for_each_subsys(ss, i) { |
32a8cf23 DL |
1193 | if (strcmp(token, ss->name)) |
1194 | continue; | |
1195 | if (ss->disabled) | |
1196 | continue; | |
1197 | ||
1198 | /* Mutually exclusive option 'all' + subsystem name */ | |
1199 | if (all_ss) | |
1200 | return -EINVAL; | |
a1a71b45 | 1201 | set_bit(i, &opts->subsys_mask); |
32a8cf23 DL |
1202 | one_ss = true; |
1203 | ||
1204 | break; | |
1205 | } | |
1206 | if (i == CGROUP_SUBSYS_COUNT) | |
1207 | return -ENOENT; | |
1208 | } | |
1209 | ||
2c6ab6d2 PM |
1210 | /* Consistency checks */ |
1211 | ||
873fe09e TH |
1212 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1213 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); | |
1214 | ||
d3ba07c3 TH |
1215 | if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) || |
1216 | opts->cpuset_clone_children || opts->release_agent || | |
1217 | opts->name) { | |
1218 | pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n"); | |
873fe09e TH |
1219 | return -EINVAL; |
1220 | } | |
a2dd4247 TH |
1221 | } else { |
1222 | /* | |
1223 | * If the 'all' option was specified select all the | |
1224 | * subsystems, otherwise if 'none', 'name=' and a subsystem | |
1225 | * name options were not specified, let's default to 'all' | |
1226 | */ | |
1227 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1228 | for_each_subsys(ss, i) | |
1229 | if (!ss->disabled) | |
1230 | set_bit(i, &opts->subsys_mask); | |
873fe09e | 1231 | |
a2dd4247 TH |
1232 | /* |
1233 | * We either have to specify by name or by subsystems. (So | |
1234 | * all empty hierarchies must have a name). | |
1235 | */ | |
1236 | if (!opts->subsys_mask && !opts->name) | |
873fe09e | 1237 | return -EINVAL; |
873fe09e TH |
1238 | } |
1239 | ||
f9ab5b5b LZ |
1240 | /* |
1241 | * Option noprefix was introduced just for backward compatibility | |
1242 | * with the old cpuset, so we allow noprefix only if mounting just | |
1243 | * the cpuset subsystem. | |
1244 | */ | |
93438629 | 1245 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1246 | return -EINVAL; |
1247 | ||
2c6ab6d2 PM |
1248 | |
1249 | /* Can't specify "none" and some subsystems */ | |
a1a71b45 | 1250 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1251 | return -EINVAL; |
1252 | ||
ddbcc7e8 PM |
1253 | return 0; |
1254 | } | |
1255 | ||
2bd59d48 | 1256 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1257 | { |
1258 | int ret = 0; | |
3dd06ffa | 1259 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1260 | struct cgroup_sb_opts opts; |
a1a71b45 | 1261 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1262 | |
873fe09e TH |
1263 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1264 | pr_err("cgroup: sane_behavior: remount is not allowed\n"); | |
1265 | return -EINVAL; | |
1266 | } | |
1267 | ||
ace2bee8 | 1268 | mutex_lock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
1269 | mutex_lock(&cgroup_mutex); |
1270 | ||
1271 | /* See what subsystems are wanted */ | |
1272 | ret = parse_cgroupfs_options(data, &opts); | |
1273 | if (ret) | |
1274 | goto out_unlock; | |
1275 | ||
3dd06ffa | 1276 | if (opts.subsys_mask != root->cgrp.subsys_mask || opts.release_agent) |
8b5a5a9d TH |
1277 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", |
1278 | task_tgid_nr(current), current->comm); | |
1279 | ||
3dd06ffa TH |
1280 | added_mask = opts.subsys_mask & ~root->cgrp.subsys_mask; |
1281 | removed_mask = root->cgrp.subsys_mask & ~opts.subsys_mask; | |
13af07df | 1282 | |
cf5d5941 | 1283 | /* Don't allow flags or name to change at remount */ |
0ce6cba3 | 1284 | if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) || |
cf5d5941 | 1285 | (opts.name && strcmp(opts.name, root->name))) { |
0ce6cba3 TH |
1286 | pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n", |
1287 | opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "", | |
1288 | root->flags & CGRP_ROOT_OPTION_MASK, root->name); | |
c6d57f33 PM |
1289 | ret = -EINVAL; |
1290 | goto out_unlock; | |
1291 | } | |
1292 | ||
f172e67c | 1293 | /* remounting is not allowed for populated hierarchies */ |
3dd06ffa | 1294 | if (!list_empty(&root->cgrp.children)) { |
f172e67c | 1295 | ret = -EBUSY; |
0670e08b | 1296 | goto out_unlock; |
cf5d5941 | 1297 | } |
ddbcc7e8 | 1298 | |
5df36032 | 1299 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1300 | if (ret) |
0670e08b | 1301 | goto out_unlock; |
ddbcc7e8 | 1302 | |
3dd06ffa | 1303 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1304 | |
69e943b7 TH |
1305 | if (opts.release_agent) { |
1306 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1307 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1308 | spin_unlock(&release_agent_path_lock); |
1309 | } | |
ddbcc7e8 | 1310 | out_unlock: |
66bdc9cf | 1311 | kfree(opts.release_agent); |
c6d57f33 | 1312 | kfree(opts.name); |
ddbcc7e8 | 1313 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 1314 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
1315 | return ret; |
1316 | } | |
1317 | ||
afeb0f9f TH |
1318 | /* |
1319 | * To reduce the fork() overhead for systems that are not actually using | |
1320 | * their cgroups capability, we don't maintain the lists running through | |
1321 | * each css_set to its tasks until we see the list actually used - in other | |
1322 | * words after the first mount. | |
1323 | */ | |
1324 | static bool use_task_css_set_links __read_mostly; | |
1325 | ||
1326 | static void cgroup_enable_task_cg_lists(void) | |
1327 | { | |
1328 | struct task_struct *p, *g; | |
1329 | ||
96d365e0 | 1330 | down_write(&css_set_rwsem); |
afeb0f9f TH |
1331 | |
1332 | if (use_task_css_set_links) | |
1333 | goto out_unlock; | |
1334 | ||
1335 | use_task_css_set_links = true; | |
1336 | ||
1337 | /* | |
1338 | * We need tasklist_lock because RCU is not safe against | |
1339 | * while_each_thread(). Besides, a forking task that has passed | |
1340 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1341 | * is not guaranteed to have its child immediately visible in the | |
1342 | * tasklist if we walk through it with RCU. | |
1343 | */ | |
1344 | read_lock(&tasklist_lock); | |
1345 | do_each_thread(g, p) { | |
afeb0f9f TH |
1346 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1347 | task_css_set(p) != &init_css_set); | |
1348 | ||
1349 | /* | |
1350 | * We should check if the process is exiting, otherwise | |
1351 | * it will race with cgroup_exit() in that the list | |
1352 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1353 | * Do it while holding siglock so that we don't end up |
1354 | * racing against cgroup_exit(). | |
afeb0f9f | 1355 | */ |
f153ad11 | 1356 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1357 | if (!(p->flags & PF_EXITING)) { |
1358 | struct css_set *cset = task_css_set(p); | |
1359 | ||
1360 | list_add(&p->cg_list, &cset->tasks); | |
1361 | get_css_set(cset); | |
1362 | } | |
f153ad11 | 1363 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1364 | } while_each_thread(g, p); |
1365 | read_unlock(&tasklist_lock); | |
1366 | out_unlock: | |
96d365e0 | 1367 | up_write(&css_set_rwsem); |
afeb0f9f | 1368 | } |
ddbcc7e8 | 1369 | |
cc31edce PM |
1370 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1371 | { | |
2bd59d48 | 1372 | atomic_set(&cgrp->refcnt, 1); |
cc31edce PM |
1373 | INIT_LIST_HEAD(&cgrp->sibling); |
1374 | INIT_LIST_HEAD(&cgrp->children); | |
69d0206c | 1375 | INIT_LIST_HEAD(&cgrp->cset_links); |
cc31edce | 1376 | INIT_LIST_HEAD(&cgrp->release_list); |
72a8cb30 BB |
1377 | INIT_LIST_HEAD(&cgrp->pidlists); |
1378 | mutex_init(&cgrp->pidlist_mutex); | |
67f4c36f | 1379 | cgrp->dummy_css.cgroup = cgrp; |
cc31edce | 1380 | } |
c6d57f33 | 1381 | |
3dd06ffa | 1382 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1383 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1384 | { |
3dd06ffa | 1385 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1386 | |
ddbcc7e8 | 1387 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1388 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1389 | cgrp->root = root; |
cc31edce | 1390 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1391 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1392 | |
c6d57f33 PM |
1393 | root->flags = opts->flags; |
1394 | if (opts->release_agent) | |
1395 | strcpy(root->release_agent_path, opts->release_agent); | |
1396 | if (opts->name) | |
1397 | strcpy(root->name, opts->name); | |
2260e7fc | 1398 | if (opts->cpuset_clone_children) |
3dd06ffa | 1399 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1400 | } |
1401 | ||
3dd06ffa | 1402 | static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) |
2c6ab6d2 | 1403 | { |
d427dfeb | 1404 | LIST_HEAD(tmp_links); |
3dd06ffa | 1405 | struct cgroup *root_cgrp = &root->cgrp; |
d427dfeb | 1406 | struct css_set *cset; |
d427dfeb | 1407 | int i, ret; |
2c6ab6d2 | 1408 | |
d427dfeb TH |
1409 | lockdep_assert_held(&cgroup_tree_mutex); |
1410 | lockdep_assert_held(&cgroup_mutex); | |
c6d57f33 | 1411 | |
d427dfeb TH |
1412 | ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL); |
1413 | if (ret < 0) | |
2bd59d48 | 1414 | goto out; |
d427dfeb | 1415 | root_cgrp->id = ret; |
c6d57f33 | 1416 | |
d427dfeb | 1417 | /* |
96d365e0 | 1418 | * We're accessing css_set_count without locking css_set_rwsem here, |
d427dfeb TH |
1419 | * but that's OK - it can only be increased by someone holding |
1420 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1421 | * have some link structures left over | |
1422 | */ | |
1423 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1424 | if (ret) | |
2bd59d48 | 1425 | goto out; |
ddbcc7e8 | 1426 | |
985ed670 | 1427 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1428 | if (ret) |
2bd59d48 | 1429 | goto out; |
ddbcc7e8 | 1430 | |
2bd59d48 TH |
1431 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1432 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1433 | root_cgrp); | |
1434 | if (IS_ERR(root->kf_root)) { | |
1435 | ret = PTR_ERR(root->kf_root); | |
1436 | goto exit_root_id; | |
1437 | } | |
1438 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1439 | |
d427dfeb TH |
1440 | ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true); |
1441 | if (ret) | |
2bd59d48 | 1442 | goto destroy_root; |
ddbcc7e8 | 1443 | |
5df36032 | 1444 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1445 | if (ret) |
2bd59d48 | 1446 | goto destroy_root; |
ddbcc7e8 | 1447 | |
d427dfeb TH |
1448 | /* |
1449 | * There must be no failure case after here, since rebinding takes | |
1450 | * care of subsystems' refcounts, which are explicitly dropped in | |
1451 | * the failure exit path. | |
1452 | */ | |
1453 | list_add(&root->root_list, &cgroup_roots); | |
1454 | cgroup_root_count++; | |
0df6a63f | 1455 | |
d427dfeb | 1456 | /* |
3dd06ffa | 1457 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1458 | * objects. |
1459 | */ | |
96d365e0 | 1460 | down_write(&css_set_rwsem); |
d427dfeb TH |
1461 | hash_for_each(css_set_table, i, cset, hlist) |
1462 | link_css_set(&tmp_links, cset, root_cgrp); | |
96d365e0 | 1463 | up_write(&css_set_rwsem); |
ddbcc7e8 | 1464 | |
d427dfeb | 1465 | BUG_ON(!list_empty(&root_cgrp->children)); |
3c9c825b | 1466 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1467 | |
2bd59d48 | 1468 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1469 | ret = 0; |
2bd59d48 | 1470 | goto out; |
d427dfeb | 1471 | |
2bd59d48 TH |
1472 | destroy_root: |
1473 | kernfs_destroy_root(root->kf_root); | |
1474 | root->kf_root = NULL; | |
1475 | exit_root_id: | |
d427dfeb | 1476 | cgroup_exit_root_id(root); |
2bd59d48 | 1477 | out: |
d427dfeb TH |
1478 | free_cgrp_cset_links(&tmp_links); |
1479 | return ret; | |
ddbcc7e8 PM |
1480 | } |
1481 | ||
f7e83571 | 1482 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1483 | int flags, const char *unused_dev_name, |
f7e83571 | 1484 | void *data) |
ddbcc7e8 | 1485 | { |
3dd06ffa | 1486 | struct cgroup_root *root; |
ddbcc7e8 | 1487 | struct cgroup_sb_opts opts; |
2bd59d48 | 1488 | struct dentry *dentry; |
8e30e2b8 | 1489 | int ret; |
c6b3d5bc | 1490 | bool new_sb; |
ddbcc7e8 | 1491 | |
56fde9e0 TH |
1492 | /* |
1493 | * The first time anyone tries to mount a cgroup, enable the list | |
1494 | * linking each css_set to its tasks and fix up all existing tasks. | |
1495 | */ | |
1496 | if (!use_task_css_set_links) | |
1497 | cgroup_enable_task_cg_lists(); | |
776f02fa | 1498 | retry: |
8e30e2b8 | 1499 | mutex_lock(&cgroup_tree_mutex); |
aae8aab4 | 1500 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
1501 | |
1502 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 1503 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 1504 | if (ret) |
8e30e2b8 | 1505 | goto out_unlock; |
ddbcc7e8 | 1506 | |
2bd59d48 | 1507 | /* look for a matching existing root */ |
a2dd4247 TH |
1508 | if (!opts.subsys_mask && !opts.none && !opts.name) { |
1509 | cgrp_dfl_root_visible = true; | |
1510 | root = &cgrp_dfl_root; | |
1511 | cgroup_get(&root->cgrp); | |
1512 | ret = 0; | |
1513 | goto out_unlock; | |
ddbcc7e8 PM |
1514 | } |
1515 | ||
985ed670 | 1516 | for_each_root(root) { |
2bd59d48 | 1517 | bool name_match = false; |
3126121f | 1518 | |
3dd06ffa | 1519 | if (root == &cgrp_dfl_root) |
985ed670 | 1520 | continue; |
3126121f | 1521 | |
cf5d5941 | 1522 | /* |
2bd59d48 TH |
1523 | * If we asked for a name then it must match. Also, if |
1524 | * name matches but sybsys_mask doesn't, we should fail. | |
1525 | * Remember whether name matched. | |
cf5d5941 | 1526 | */ |
2bd59d48 TH |
1527 | if (opts.name) { |
1528 | if (strcmp(opts.name, root->name)) | |
1529 | continue; | |
1530 | name_match = true; | |
1531 | } | |
ddbcc7e8 | 1532 | |
c6d57f33 | 1533 | /* |
2bd59d48 TH |
1534 | * If we asked for subsystems (or explicitly for no |
1535 | * subsystems) then they must match. | |
c6d57f33 | 1536 | */ |
2bd59d48 | 1537 | if ((opts.subsys_mask || opts.none) && |
3dd06ffa | 1538 | (opts.subsys_mask != root->cgrp.subsys_mask)) { |
2bd59d48 TH |
1539 | if (!name_match) |
1540 | continue; | |
1541 | ret = -EBUSY; | |
1542 | goto out_unlock; | |
1543 | } | |
873fe09e | 1544 | |
c7ba8287 | 1545 | if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) { |
2a0ff3fb JL |
1546 | if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { |
1547 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); | |
1548 | ret = -EINVAL; | |
8e30e2b8 | 1549 | goto out_unlock; |
2a0ff3fb JL |
1550 | } else { |
1551 | pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); | |
1552 | } | |
873fe09e | 1553 | } |
ddbcc7e8 | 1554 | |
776f02fa | 1555 | /* |
3dd06ffa | 1556 | * A root's lifetime is governed by its root cgroup. Zero |
776f02fa TH |
1557 | * ref indicate that the root is being destroyed. Wait for |
1558 | * destruction to complete so that the subsystems are free. | |
1559 | * We can use wait_queue for the wait but this path is | |
1560 | * super cold. Let's just sleep for a bit and retry. | |
1561 | */ | |
3dd06ffa | 1562 | if (!atomic_inc_not_zero(&root->cgrp.refcnt)) { |
776f02fa TH |
1563 | mutex_unlock(&cgroup_mutex); |
1564 | mutex_unlock(&cgroup_tree_mutex); | |
6534fd6c LZ |
1565 | kfree(opts.release_agent); |
1566 | kfree(opts.name); | |
776f02fa TH |
1567 | msleep(10); |
1568 | goto retry; | |
1569 | } | |
ddbcc7e8 | 1570 | |
776f02fa | 1571 | ret = 0; |
2bd59d48 | 1572 | goto out_unlock; |
ddbcc7e8 | 1573 | } |
ddbcc7e8 | 1574 | |
817929ec | 1575 | /* |
172a2c06 TH |
1576 | * No such thing, create a new one. name= matching without subsys |
1577 | * specification is allowed for already existing hierarchies but we | |
1578 | * can't create new one without subsys specification. | |
817929ec | 1579 | */ |
172a2c06 TH |
1580 | if (!opts.subsys_mask && !opts.none) { |
1581 | ret = -EINVAL; | |
1582 | goto out_unlock; | |
817929ec | 1583 | } |
817929ec | 1584 | |
172a2c06 TH |
1585 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
1586 | if (!root) { | |
1587 | ret = -ENOMEM; | |
2bd59d48 | 1588 | goto out_unlock; |
839ec545 | 1589 | } |
e5f6a860 | 1590 | |
172a2c06 TH |
1591 | init_cgroup_root(root, &opts); |
1592 | ||
35585573 | 1593 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
1594 | if (ret) |
1595 | cgroup_free_root(root); | |
fa3ca07e | 1596 | |
8e30e2b8 | 1597 | out_unlock: |
ddbcc7e8 | 1598 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 1599 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 | 1600 | |
c6d57f33 PM |
1601 | kfree(opts.release_agent); |
1602 | kfree(opts.name); | |
03b1cde6 | 1603 | |
2bd59d48 | 1604 | if (ret) |
8e30e2b8 | 1605 | return ERR_PTR(ret); |
2bd59d48 | 1606 | |
c6b3d5bc LZ |
1607 | dentry = kernfs_mount(fs_type, flags, root->kf_root, &new_sb); |
1608 | if (IS_ERR(dentry) || !new_sb) | |
3dd06ffa | 1609 | cgroup_put(&root->cgrp); |
2bd59d48 TH |
1610 | return dentry; |
1611 | } | |
1612 | ||
1613 | static void cgroup_kill_sb(struct super_block *sb) | |
1614 | { | |
1615 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 1616 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 1617 | |
3dd06ffa | 1618 | cgroup_put(&root->cgrp); |
2bd59d48 | 1619 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
1620 | } |
1621 | ||
1622 | static struct file_system_type cgroup_fs_type = { | |
1623 | .name = "cgroup", | |
f7e83571 | 1624 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1625 | .kill_sb = cgroup_kill_sb, |
1626 | }; | |
1627 | ||
676db4af GKH |
1628 | static struct kobject *cgroup_kobj; |
1629 | ||
857a2beb | 1630 | /** |
913ffdb5 | 1631 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 1632 | * @task: target task |
857a2beb TH |
1633 | * @buf: the buffer to write the path into |
1634 | * @buflen: the length of the buffer | |
1635 | * | |
913ffdb5 TH |
1636 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
1637 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
1638 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
1639 | * cgroup controller callbacks. | |
1640 | * | |
e61734c5 | 1641 | * Return value is the same as kernfs_path(). |
857a2beb | 1642 | */ |
e61734c5 | 1643 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 1644 | { |
3dd06ffa | 1645 | struct cgroup_root *root; |
913ffdb5 | 1646 | struct cgroup *cgrp; |
e61734c5 TH |
1647 | int hierarchy_id = 1; |
1648 | char *path = NULL; | |
857a2beb TH |
1649 | |
1650 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 1651 | down_read(&css_set_rwsem); |
857a2beb | 1652 | |
913ffdb5 TH |
1653 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
1654 | ||
857a2beb TH |
1655 | if (root) { |
1656 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 1657 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
1658 | } else { |
1659 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
1660 | if (strlcpy(buf, "/", buflen) < buflen) |
1661 | path = buf; | |
857a2beb TH |
1662 | } |
1663 | ||
96d365e0 | 1664 | up_read(&css_set_rwsem); |
857a2beb | 1665 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 1666 | return path; |
857a2beb | 1667 | } |
913ffdb5 | 1668 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 1669 | |
b3dc094e | 1670 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 1671 | struct cgroup_taskset { |
b3dc094e TH |
1672 | /* the src and dst cset list running through cset->mg_node */ |
1673 | struct list_head src_csets; | |
1674 | struct list_head dst_csets; | |
1675 | ||
1676 | /* | |
1677 | * Fields for cgroup_taskset_*() iteration. | |
1678 | * | |
1679 | * Before migration is committed, the target migration tasks are on | |
1680 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
1681 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
1682 | * or ->dst_csets depending on whether migration is committed. | |
1683 | * | |
1684 | * ->cur_csets and ->cur_task point to the current task position | |
1685 | * during iteration. | |
1686 | */ | |
1687 | struct list_head *csets; | |
1688 | struct css_set *cur_cset; | |
1689 | struct task_struct *cur_task; | |
2f7ee569 TH |
1690 | }; |
1691 | ||
1692 | /** | |
1693 | * cgroup_taskset_first - reset taskset and return the first task | |
1694 | * @tset: taskset of interest | |
1695 | * | |
1696 | * @tset iteration is initialized and the first task is returned. | |
1697 | */ | |
1698 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1699 | { | |
b3dc094e TH |
1700 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
1701 | tset->cur_task = NULL; | |
1702 | ||
1703 | return cgroup_taskset_next(tset); | |
2f7ee569 | 1704 | } |
2f7ee569 TH |
1705 | |
1706 | /** | |
1707 | * cgroup_taskset_next - iterate to the next task in taskset | |
1708 | * @tset: taskset of interest | |
1709 | * | |
1710 | * Return the next task in @tset. Iteration must have been initialized | |
1711 | * with cgroup_taskset_first(). | |
1712 | */ | |
1713 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1714 | { | |
b3dc094e TH |
1715 | struct css_set *cset = tset->cur_cset; |
1716 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 1717 | |
b3dc094e TH |
1718 | while (&cset->mg_node != tset->csets) { |
1719 | if (!task) | |
1720 | task = list_first_entry(&cset->mg_tasks, | |
1721 | struct task_struct, cg_list); | |
1722 | else | |
1723 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 1724 | |
b3dc094e TH |
1725 | if (&task->cg_list != &cset->mg_tasks) { |
1726 | tset->cur_cset = cset; | |
1727 | tset->cur_task = task; | |
1728 | return task; | |
1729 | } | |
2f7ee569 | 1730 | |
b3dc094e TH |
1731 | cset = list_next_entry(cset, mg_node); |
1732 | task = NULL; | |
1733 | } | |
2f7ee569 | 1734 | |
b3dc094e | 1735 | return NULL; |
2f7ee569 | 1736 | } |
2f7ee569 | 1737 | |
cb0f1fe9 | 1738 | /** |
74a1166d | 1739 | * cgroup_task_migrate - move a task from one cgroup to another. |
cb0f1fe9 TH |
1740 | * @old_cgrp; the cgroup @tsk is being migrated from |
1741 | * @tsk: the task being migrated | |
1742 | * @new_cset: the new css_set @tsk is being attached to | |
74a1166d | 1743 | * |
cb0f1fe9 | 1744 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. |
74a1166d | 1745 | */ |
5abb8855 TH |
1746 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
1747 | struct task_struct *tsk, | |
1748 | struct css_set *new_cset) | |
74a1166d | 1749 | { |
5abb8855 | 1750 | struct css_set *old_cset; |
74a1166d | 1751 | |
cb0f1fe9 TH |
1752 | lockdep_assert_held(&cgroup_mutex); |
1753 | lockdep_assert_held(&css_set_rwsem); | |
1754 | ||
74a1166d | 1755 | /* |
026085ef MSB |
1756 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1757 | * setting such that we can't race against cgroup_exit() changing the | |
1758 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1759 | */ |
c84cdf75 | 1760 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 1761 | old_cset = task_css_set(tsk); |
74a1166d | 1762 | |
b3dc094e | 1763 | get_css_set(new_cset); |
5abb8855 | 1764 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d | 1765 | |
1b9aba49 TH |
1766 | /* |
1767 | * Use move_tail so that cgroup_taskset_first() still returns the | |
1768 | * leader after migration. This works because cgroup_migrate() | |
1769 | * ensures that the dst_cset of the leader is the first on the | |
1770 | * tset's dst_csets list. | |
1771 | */ | |
1772 | list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); | |
74a1166d BB |
1773 | |
1774 | /* | |
5abb8855 TH |
1775 | * We just gained a reference on old_cset by taking it from the |
1776 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
1777 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 1778 | */ |
5abb8855 | 1779 | set_bit(CGRP_RELEASABLE, &old_cgrp->flags); |
cb0f1fe9 | 1780 | put_css_set_locked(old_cset, false); |
74a1166d BB |
1781 | } |
1782 | ||
a043e3b2 | 1783 | /** |
1958d2d5 TH |
1784 | * cgroup_migrate_finish - cleanup after attach |
1785 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 1786 | * |
1958d2d5 TH |
1787 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
1788 | * those functions for details. | |
74a1166d | 1789 | */ |
1958d2d5 | 1790 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 1791 | { |
1958d2d5 | 1792 | struct css_set *cset, *tmp_cset; |
74a1166d | 1793 | |
1958d2d5 TH |
1794 | lockdep_assert_held(&cgroup_mutex); |
1795 | ||
1796 | down_write(&css_set_rwsem); | |
1797 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { | |
1798 | cset->mg_src_cgrp = NULL; | |
1799 | cset->mg_dst_cset = NULL; | |
1800 | list_del_init(&cset->mg_preload_node); | |
1801 | put_css_set_locked(cset, false); | |
1802 | } | |
1803 | up_write(&css_set_rwsem); | |
1804 | } | |
1805 | ||
1806 | /** | |
1807 | * cgroup_migrate_add_src - add a migration source css_set | |
1808 | * @src_cset: the source css_set to add | |
1809 | * @dst_cgrp: the destination cgroup | |
1810 | * @preloaded_csets: list of preloaded css_sets | |
1811 | * | |
1812 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
1813 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
1814 | * up by cgroup_migrate_finish(). | |
1815 | * | |
1816 | * This function may be called without holding threadgroup_lock even if the | |
1817 | * target is a process. Threads may be created and destroyed but as long | |
1818 | * as cgroup_mutex is not dropped, no new css_set can be put into play and | |
1819 | * the preloaded css_sets are guaranteed to cover all migrations. | |
1820 | */ | |
1821 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
1822 | struct cgroup *dst_cgrp, | |
1823 | struct list_head *preloaded_csets) | |
1824 | { | |
1825 | struct cgroup *src_cgrp; | |
1826 | ||
1827 | lockdep_assert_held(&cgroup_mutex); | |
1828 | lockdep_assert_held(&css_set_rwsem); | |
1829 | ||
1830 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
1831 | ||
1832 | /* nothing to do if this cset already belongs to the cgroup */ | |
1833 | if (src_cgrp == dst_cgrp) | |
1834 | return; | |
1835 | ||
1836 | if (!list_empty(&src_cset->mg_preload_node)) | |
1837 | return; | |
1838 | ||
1839 | WARN_ON(src_cset->mg_src_cgrp); | |
1840 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
1841 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
1842 | ||
1843 | src_cset->mg_src_cgrp = src_cgrp; | |
1844 | get_css_set(src_cset); | |
1845 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
1846 | } | |
1847 | ||
1848 | /** | |
1849 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
1850 | * @dst_cgrp: the destination cgroup | |
1851 | * @preloaded_csets: list of preloaded source css_sets | |
1852 | * | |
1853 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
1854 | * have been preloaded to @preloaded_csets. This function looks up and | |
1855 | * pins all destination css_sets, links each to its source, and put them on | |
1856 | * @preloaded_csets. | |
1857 | * | |
1858 | * This function must be called after cgroup_migrate_add_src() has been | |
1859 | * called on each migration source css_set. After migration is performed | |
1860 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
1861 | * @preloaded_csets. | |
1862 | */ | |
1863 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
1864 | struct list_head *preloaded_csets) | |
1865 | { | |
1866 | LIST_HEAD(csets); | |
1867 | struct css_set *src_cset; | |
1868 | ||
1869 | lockdep_assert_held(&cgroup_mutex); | |
1870 | ||
1871 | /* look up the dst cset for each src cset and link it to src */ | |
1872 | list_for_each_entry(src_cset, preloaded_csets, mg_preload_node) { | |
1873 | struct css_set *dst_cset; | |
1874 | ||
1875 | dst_cset = find_css_set(src_cset, dst_cgrp); | |
1876 | if (!dst_cset) | |
1877 | goto err; | |
1878 | ||
1879 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
1880 | src_cset->mg_dst_cset = dst_cset; | |
1881 | ||
1882 | if (list_empty(&dst_cset->mg_preload_node)) | |
1883 | list_add(&dst_cset->mg_preload_node, &csets); | |
1884 | else | |
1885 | put_css_set(dst_cset, false); | |
1886 | } | |
1887 | ||
1888 | list_splice(&csets, preloaded_csets); | |
1889 | return 0; | |
1890 | err: | |
1891 | cgroup_migrate_finish(&csets); | |
1892 | return -ENOMEM; | |
1893 | } | |
1894 | ||
1895 | /** | |
1896 | * cgroup_migrate - migrate a process or task to a cgroup | |
1897 | * @cgrp: the destination cgroup | |
1898 | * @leader: the leader of the process or the task to migrate | |
1899 | * @threadgroup: whether @leader points to the whole process or a single task | |
1900 | * | |
1901 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1902 | * process, the caller must be holding threadgroup_lock of @leader. The | |
1903 | * caller is also responsible for invoking cgroup_migrate_add_src() and | |
1904 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
1905 | * function and following up with cgroup_migrate_finish(). | |
1906 | * | |
1907 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
1908 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
1909 | * failure, when migrating multiple targets, the success or failure can be | |
1910 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
1911 | * actually starting migrating. | |
1912 | */ | |
1913 | static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader, | |
1914 | bool threadgroup) | |
74a1166d | 1915 | { |
b3dc094e TH |
1916 | struct cgroup_taskset tset = { |
1917 | .src_csets = LIST_HEAD_INIT(tset.src_csets), | |
1918 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), | |
1919 | .csets = &tset.src_csets, | |
1920 | }; | |
1c6727af | 1921 | struct cgroup_subsys_state *css, *failed_css = NULL; |
b3dc094e TH |
1922 | struct css_set *cset, *tmp_cset; |
1923 | struct task_struct *task, *tmp_task; | |
1924 | int i, ret; | |
74a1166d | 1925 | |
fb5d2b4c MSB |
1926 | /* |
1927 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
1928 | * already PF_EXITING could be freed from underneath us unless we | |
1929 | * take an rcu_read_lock. | |
1930 | */ | |
b3dc094e | 1931 | down_write(&css_set_rwsem); |
fb5d2b4c | 1932 | rcu_read_lock(); |
9db8de37 | 1933 | task = leader; |
74a1166d | 1934 | do { |
9db8de37 TH |
1935 | /* @task either already exited or can't exit until the end */ |
1936 | if (task->flags & PF_EXITING) | |
ea84753c | 1937 | goto next; |
134d3373 | 1938 | |
eaf797ab TH |
1939 | /* leave @task alone if post_fork() hasn't linked it yet */ |
1940 | if (list_empty(&task->cg_list)) | |
ea84753c | 1941 | goto next; |
cd3d0952 | 1942 | |
b3dc094e | 1943 | cset = task_css_set(task); |
1958d2d5 | 1944 | if (!cset->mg_src_cgrp) |
ea84753c | 1945 | goto next; |
b3dc094e | 1946 | |
61d1d219 | 1947 | /* |
1b9aba49 TH |
1948 | * cgroup_taskset_first() must always return the leader. |
1949 | * Take care to avoid disturbing the ordering. | |
61d1d219 | 1950 | */ |
1b9aba49 TH |
1951 | list_move_tail(&task->cg_list, &cset->mg_tasks); |
1952 | if (list_empty(&cset->mg_node)) | |
1953 | list_add_tail(&cset->mg_node, &tset.src_csets); | |
1954 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
1955 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
1956 | &tset.dst_csets); | |
ea84753c | 1957 | next: |
081aa458 LZ |
1958 | if (!threadgroup) |
1959 | break; | |
9db8de37 | 1960 | } while_each_thread(leader, task); |
fb5d2b4c | 1961 | rcu_read_unlock(); |
b3dc094e | 1962 | up_write(&css_set_rwsem); |
74a1166d | 1963 | |
134d3373 | 1964 | /* methods shouldn't be called if no task is actually migrating */ |
b3dc094e TH |
1965 | if (list_empty(&tset.src_csets)) |
1966 | return 0; | |
134d3373 | 1967 | |
1958d2d5 | 1968 | /* check that we can legitimately attach to the cgroup */ |
1c6727af TH |
1969 | for_each_css(css, i, cgrp) { |
1970 | if (css->ss->can_attach) { | |
9db8de37 TH |
1971 | ret = css->ss->can_attach(css, &tset); |
1972 | if (ret) { | |
1c6727af | 1973 | failed_css = css; |
74a1166d BB |
1974 | goto out_cancel_attach; |
1975 | } | |
1976 | } | |
74a1166d BB |
1977 | } |
1978 | ||
1979 | /* | |
1958d2d5 TH |
1980 | * Now that we're guaranteed success, proceed to move all tasks to |
1981 | * the new cgroup. There are no failure cases after here, so this | |
1982 | * is the commit point. | |
74a1166d | 1983 | */ |
cb0f1fe9 | 1984 | down_write(&css_set_rwsem); |
b3dc094e TH |
1985 | list_for_each_entry(cset, &tset.src_csets, mg_node) { |
1986 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) | |
1987 | cgroup_task_migrate(cset->mg_src_cgrp, task, | |
1988 | cset->mg_dst_cset); | |
74a1166d | 1989 | } |
cb0f1fe9 | 1990 | up_write(&css_set_rwsem); |
74a1166d BB |
1991 | |
1992 | /* | |
1958d2d5 TH |
1993 | * Migration is committed, all target tasks are now on dst_csets. |
1994 | * Nothing is sensitive to fork() after this point. Notify | |
1995 | * controllers that migration is complete. | |
74a1166d | 1996 | */ |
1958d2d5 | 1997 | tset.csets = &tset.dst_csets; |
74a1166d | 1998 | |
1c6727af TH |
1999 | for_each_css(css, i, cgrp) |
2000 | if (css->ss->attach) | |
2001 | css->ss->attach(css, &tset); | |
74a1166d | 2002 | |
9db8de37 | 2003 | ret = 0; |
b3dc094e TH |
2004 | goto out_release_tset; |
2005 | ||
74a1166d | 2006 | out_cancel_attach: |
b3dc094e TH |
2007 | for_each_css(css, i, cgrp) { |
2008 | if (css == failed_css) | |
2009 | break; | |
2010 | if (css->ss->cancel_attach) | |
2011 | css->ss->cancel_attach(css, &tset); | |
74a1166d | 2012 | } |
b3dc094e TH |
2013 | out_release_tset: |
2014 | down_write(&css_set_rwsem); | |
2015 | list_splice_init(&tset.dst_csets, &tset.src_csets); | |
2016 | list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) { | |
1b9aba49 | 2017 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
b3dc094e | 2018 | list_del_init(&cset->mg_node); |
b3dc094e TH |
2019 | } |
2020 | up_write(&css_set_rwsem); | |
9db8de37 | 2021 | return ret; |
74a1166d BB |
2022 | } |
2023 | ||
1958d2d5 TH |
2024 | /** |
2025 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2026 | * @dst_cgrp: the cgroup to attach to | |
2027 | * @leader: the task or the leader of the threadgroup to be attached | |
2028 | * @threadgroup: attach the whole threadgroup? | |
2029 | * | |
0e1d768f | 2030 | * Call holding cgroup_mutex and threadgroup_lock of @leader. |
1958d2d5 TH |
2031 | */ |
2032 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2033 | struct task_struct *leader, bool threadgroup) | |
2034 | { | |
2035 | LIST_HEAD(preloaded_csets); | |
2036 | struct task_struct *task; | |
2037 | int ret; | |
2038 | ||
2039 | /* look up all src csets */ | |
2040 | down_read(&css_set_rwsem); | |
2041 | rcu_read_lock(); | |
2042 | task = leader; | |
2043 | do { | |
2044 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2045 | &preloaded_csets); | |
2046 | if (!threadgroup) | |
2047 | break; | |
2048 | } while_each_thread(leader, task); | |
2049 | rcu_read_unlock(); | |
2050 | up_read(&css_set_rwsem); | |
2051 | ||
2052 | /* prepare dst csets and commit */ | |
2053 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2054 | if (!ret) | |
2055 | ret = cgroup_migrate(dst_cgrp, leader, threadgroup); | |
2056 | ||
2057 | cgroup_migrate_finish(&preloaded_csets); | |
2058 | return ret; | |
74a1166d BB |
2059 | } |
2060 | ||
2061 | /* | |
2062 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2063 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2064 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2065 | */ |
74a1166d | 2066 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2067 | { |
bbcb81d0 | 2068 | struct task_struct *tsk; |
c69e8d9c | 2069 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2070 | int ret; |
2071 | ||
74a1166d BB |
2072 | if (!cgroup_lock_live_group(cgrp)) |
2073 | return -ENODEV; | |
2074 | ||
b78949eb MSB |
2075 | retry_find_task: |
2076 | rcu_read_lock(); | |
bbcb81d0 | 2077 | if (pid) { |
73507f33 | 2078 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2079 | if (!tsk) { |
2080 | rcu_read_unlock(); | |
dd4b0a46 | 2081 | ret = -ESRCH; |
b78949eb | 2082 | goto out_unlock_cgroup; |
bbcb81d0 | 2083 | } |
74a1166d BB |
2084 | /* |
2085 | * even if we're attaching all tasks in the thread group, we | |
2086 | * only need to check permissions on one of them. | |
2087 | */ | |
c69e8d9c | 2088 | tcred = __task_cred(tsk); |
14a590c3 EB |
2089 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
2090 | !uid_eq(cred->euid, tcred->uid) && | |
2091 | !uid_eq(cred->euid, tcred->suid)) { | |
c69e8d9c | 2092 | rcu_read_unlock(); |
b78949eb MSB |
2093 | ret = -EACCES; |
2094 | goto out_unlock_cgroup; | |
bbcb81d0 | 2095 | } |
b78949eb MSB |
2096 | } else |
2097 | tsk = current; | |
cd3d0952 TH |
2098 | |
2099 | if (threadgroup) | |
b78949eb | 2100 | tsk = tsk->group_leader; |
c4c27fbd MG |
2101 | |
2102 | /* | |
14a40ffc | 2103 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2104 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2105 | * with no rt_runtime allocated. Just say no. | |
2106 | */ | |
14a40ffc | 2107 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd MG |
2108 | ret = -EINVAL; |
2109 | rcu_read_unlock(); | |
2110 | goto out_unlock_cgroup; | |
2111 | } | |
2112 | ||
b78949eb MSB |
2113 | get_task_struct(tsk); |
2114 | rcu_read_unlock(); | |
2115 | ||
2116 | threadgroup_lock(tsk); | |
2117 | if (threadgroup) { | |
2118 | if (!thread_group_leader(tsk)) { | |
2119 | /* | |
2120 | * a race with de_thread from another thread's exec() | |
2121 | * may strip us of our leadership, if this happens, | |
2122 | * there is no choice but to throw this task away and | |
2123 | * try again; this is | |
2124 | * "double-double-toil-and-trouble-check locking". | |
2125 | */ | |
2126 | threadgroup_unlock(tsk); | |
2127 | put_task_struct(tsk); | |
2128 | goto retry_find_task; | |
2129 | } | |
081aa458 LZ |
2130 | } |
2131 | ||
2132 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
2133 | ||
cd3d0952 TH |
2134 | threadgroup_unlock(tsk); |
2135 | ||
bbcb81d0 | 2136 | put_task_struct(tsk); |
b78949eb | 2137 | out_unlock_cgroup: |
47cfcd09 | 2138 | mutex_unlock(&cgroup_mutex); |
bbcb81d0 PM |
2139 | return ret; |
2140 | } | |
2141 | ||
7ae1bad9 TH |
2142 | /** |
2143 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2144 | * @from: attach to all cgroups of a given task | |
2145 | * @tsk: the task to be attached | |
2146 | */ | |
2147 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2148 | { | |
3dd06ffa | 2149 | struct cgroup_root *root; |
7ae1bad9 TH |
2150 | int retval = 0; |
2151 | ||
47cfcd09 | 2152 | mutex_lock(&cgroup_mutex); |
985ed670 | 2153 | for_each_root(root) { |
96d365e0 TH |
2154 | struct cgroup *from_cgrp; |
2155 | ||
3dd06ffa | 2156 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2157 | continue; |
2158 | ||
96d365e0 TH |
2159 | down_read(&css_set_rwsem); |
2160 | from_cgrp = task_cgroup_from_root(from, root); | |
2161 | up_read(&css_set_rwsem); | |
7ae1bad9 | 2162 | |
6f4b7e63 | 2163 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2164 | if (retval) |
2165 | break; | |
2166 | } | |
47cfcd09 | 2167 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2168 | |
2169 | return retval; | |
2170 | } | |
2171 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2172 | ||
182446d0 TH |
2173 | static int cgroup_tasks_write(struct cgroup_subsys_state *css, |
2174 | struct cftype *cft, u64 pid) | |
74a1166d | 2175 | { |
182446d0 | 2176 | return attach_task_by_pid(css->cgroup, pid, false); |
74a1166d BB |
2177 | } |
2178 | ||
182446d0 TH |
2179 | static int cgroup_procs_write(struct cgroup_subsys_state *css, |
2180 | struct cftype *cft, u64 tgid) | |
af351026 | 2181 | { |
182446d0 | 2182 | return attach_task_by_pid(css->cgroup, tgid, true); |
af351026 PM |
2183 | } |
2184 | ||
182446d0 | 2185 | static int cgroup_release_agent_write(struct cgroup_subsys_state *css, |
4d3bb511 | 2186 | struct cftype *cft, char *buffer) |
e788e066 | 2187 | { |
3dd06ffa | 2188 | struct cgroup_root *root = css->cgroup->root; |
5f469907 TH |
2189 | |
2190 | BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX); | |
182446d0 | 2191 | if (!cgroup_lock_live_group(css->cgroup)) |
e788e066 | 2192 | return -ENODEV; |
69e943b7 | 2193 | spin_lock(&release_agent_path_lock); |
5f469907 TH |
2194 | strlcpy(root->release_agent_path, buffer, |
2195 | sizeof(root->release_agent_path)); | |
69e943b7 | 2196 | spin_unlock(&release_agent_path_lock); |
47cfcd09 | 2197 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2198 | return 0; |
2199 | } | |
2200 | ||
2da8ca82 | 2201 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2202 | { |
2da8ca82 | 2203 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2204 | |
e788e066 PM |
2205 | if (!cgroup_lock_live_group(cgrp)) |
2206 | return -ENODEV; | |
2207 | seq_puts(seq, cgrp->root->release_agent_path); | |
2208 | seq_putc(seq, '\n'); | |
47cfcd09 | 2209 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2210 | return 0; |
2211 | } | |
2212 | ||
2da8ca82 | 2213 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2214 | { |
2da8ca82 TH |
2215 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2216 | ||
2217 | seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); | |
e788e066 PM |
2218 | return 0; |
2219 | } | |
2220 | ||
2bd59d48 TH |
2221 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
2222 | size_t nbytes, loff_t off) | |
355e0c48 | 2223 | { |
2bd59d48 TH |
2224 | struct cgroup *cgrp = of->kn->parent->priv; |
2225 | struct cftype *cft = of->kn->priv; | |
2226 | struct cgroup_subsys_state *css; | |
a742c59d | 2227 | int ret; |
355e0c48 | 2228 | |
2bd59d48 TH |
2229 | /* |
2230 | * kernfs guarantees that a file isn't deleted with operations in | |
2231 | * flight, which means that the matching css is and stays alive and | |
2232 | * doesn't need to be pinned. The RCU locking is not necessary | |
2233 | * either. It's just for the convenience of using cgroup_css(). | |
2234 | */ | |
2235 | rcu_read_lock(); | |
2236 | css = cgroup_css(cgrp, cft->ss); | |
2237 | rcu_read_unlock(); | |
a742c59d TH |
2238 | |
2239 | if (cft->write_string) { | |
2240 | ret = cft->write_string(css, cft, strstrip(buf)); | |
2241 | } else if (cft->write_u64) { | |
2242 | unsigned long long v; | |
2243 | ret = kstrtoull(buf, 0, &v); | |
2244 | if (!ret) | |
2245 | ret = cft->write_u64(css, cft, v); | |
2246 | } else if (cft->write_s64) { | |
2247 | long long v; | |
2248 | ret = kstrtoll(buf, 0, &v); | |
2249 | if (!ret) | |
2250 | ret = cft->write_s64(css, cft, v); | |
2251 | } else if (cft->trigger) { | |
2252 | ret = cft->trigger(css, (unsigned int)cft->private); | |
e73d2c61 | 2253 | } else { |
a742c59d | 2254 | ret = -EINVAL; |
e73d2c61 | 2255 | } |
2bd59d48 | 2256 | |
a742c59d | 2257 | return ret ?: nbytes; |
355e0c48 PM |
2258 | } |
2259 | ||
6612f05b | 2260 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 2261 | { |
2bd59d48 | 2262 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
2263 | } |
2264 | ||
6612f05b | 2265 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 2266 | { |
2bd59d48 | 2267 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
2268 | } |
2269 | ||
6612f05b | 2270 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 2271 | { |
2bd59d48 | 2272 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
2273 | } |
2274 | ||
91796569 | 2275 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 2276 | { |
7da11279 TH |
2277 | struct cftype *cft = seq_cft(m); |
2278 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 2279 | |
2da8ca82 TH |
2280 | if (cft->seq_show) |
2281 | return cft->seq_show(m, arg); | |
e73d2c61 | 2282 | |
f4c753b7 | 2283 | if (cft->read_u64) |
896f5199 TH |
2284 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
2285 | else if (cft->read_s64) | |
2286 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
2287 | else | |
2288 | return -EINVAL; | |
2289 | return 0; | |
91796569 PM |
2290 | } |
2291 | ||
2bd59d48 TH |
2292 | static struct kernfs_ops cgroup_kf_single_ops = { |
2293 | .atomic_write_len = PAGE_SIZE, | |
2294 | .write = cgroup_file_write, | |
2295 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
2296 | }; |
2297 | ||
2bd59d48 TH |
2298 | static struct kernfs_ops cgroup_kf_ops = { |
2299 | .atomic_write_len = PAGE_SIZE, | |
2300 | .write = cgroup_file_write, | |
2301 | .seq_start = cgroup_seqfile_start, | |
2302 | .seq_next = cgroup_seqfile_next, | |
2303 | .seq_stop = cgroup_seqfile_stop, | |
2304 | .seq_show = cgroup_seqfile_show, | |
2305 | }; | |
ddbcc7e8 PM |
2306 | |
2307 | /* | |
2308 | * cgroup_rename - Only allow simple rename of directories in place. | |
2309 | */ | |
2bd59d48 TH |
2310 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
2311 | const char *new_name_str) | |
ddbcc7e8 | 2312 | { |
2bd59d48 | 2313 | struct cgroup *cgrp = kn->priv; |
65dff759 | 2314 | int ret; |
65dff759 | 2315 | |
2bd59d48 | 2316 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 2317 | return -ENOTDIR; |
2bd59d48 | 2318 | if (kn->parent != new_parent) |
ddbcc7e8 | 2319 | return -EIO; |
65dff759 | 2320 | |
6db8e85c TH |
2321 | /* |
2322 | * This isn't a proper migration and its usefulness is very | |
2323 | * limited. Disallow if sane_behavior. | |
2324 | */ | |
2325 | if (cgroup_sane_behavior(cgrp)) | |
2326 | return -EPERM; | |
099fca32 | 2327 | |
e1b2dc17 TH |
2328 | /* |
2329 | * We're gonna grab cgroup_tree_mutex which nests outside kernfs | |
2330 | * active_ref. kernfs_rename() doesn't require active_ref | |
2331 | * protection. Break them before grabbing cgroup_tree_mutex. | |
2332 | */ | |
2333 | kernfs_break_active_protection(new_parent); | |
2334 | kernfs_break_active_protection(kn); | |
099fca32 | 2335 | |
2bd59d48 TH |
2336 | mutex_lock(&cgroup_tree_mutex); |
2337 | mutex_lock(&cgroup_mutex); | |
099fca32 | 2338 | |
2bd59d48 | 2339 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 2340 | |
2bd59d48 TH |
2341 | mutex_unlock(&cgroup_mutex); |
2342 | mutex_unlock(&cgroup_tree_mutex); | |
e1b2dc17 TH |
2343 | |
2344 | kernfs_unbreak_active_protection(kn); | |
2345 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 2346 | return ret; |
099fca32 LZ |
2347 | } |
2348 | ||
2bb566cb | 2349 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) |
ddbcc7e8 | 2350 | { |
8d7e6fb0 | 2351 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
2352 | struct kernfs_node *kn; |
2353 | struct lock_class_key *key = NULL; | |
05ef1d7c | 2354 | |
2bd59d48 TH |
2355 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
2356 | key = &cft->lockdep_key; | |
2357 | #endif | |
2358 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
2359 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
2360 | NULL, false, key); | |
430af8ad | 2361 | return PTR_ERR_OR_ZERO(kn); |
ddbcc7e8 PM |
2362 | } |
2363 | ||
b1f28d31 TH |
2364 | /** |
2365 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
2366 | * @cgrp: the target cgroup | |
b1f28d31 TH |
2367 | * @cfts: array of cftypes to be added |
2368 | * @is_add: whether to add or remove | |
2369 | * | |
2370 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
2bb566cb TH |
2371 | * For removals, this function never fails. If addition fails, this |
2372 | * function doesn't remove files already added. The caller is responsible | |
2373 | * for cleaning up. | |
b1f28d31 | 2374 | */ |
2bb566cb TH |
2375 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
2376 | bool is_add) | |
ddbcc7e8 | 2377 | { |
03b1cde6 | 2378 | struct cftype *cft; |
b1f28d31 TH |
2379 | int ret; |
2380 | ||
ace2bee8 | 2381 | lockdep_assert_held(&cgroup_tree_mutex); |
db0416b6 TH |
2382 | |
2383 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 2384 | /* does cft->flags tell us to skip this file on @cgrp? */ |
8cbbf2c9 TH |
2385 | if ((cft->flags & CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
2386 | continue; | |
873fe09e TH |
2387 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) |
2388 | continue; | |
f33fddc2 G |
2389 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
2390 | continue; | |
2391 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2392 | continue; | |
2393 | ||
2739d3cc | 2394 | if (is_add) { |
2bb566cb | 2395 | ret = cgroup_add_file(cgrp, cft); |
b1f28d31 | 2396 | if (ret) { |
2739d3cc | 2397 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", |
b1f28d31 TH |
2398 | cft->name, ret); |
2399 | return ret; | |
2400 | } | |
2739d3cc LZ |
2401 | } else { |
2402 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2403 | } |
ddbcc7e8 | 2404 | } |
b1f28d31 | 2405 | return 0; |
ddbcc7e8 PM |
2406 | } |
2407 | ||
21a2d343 | 2408 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
2409 | { |
2410 | LIST_HEAD(pending); | |
2bb566cb | 2411 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 2412 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 2413 | struct cgroup_subsys_state *css; |
9ccece80 | 2414 | int ret = 0; |
8e3f6541 | 2415 | |
21a2d343 | 2416 | lockdep_assert_held(&cgroup_tree_mutex); |
8e3f6541 | 2417 | |
21a2d343 | 2418 | /* don't bother if @ss isn't attached */ |
3dd06ffa | 2419 | if (ss->root == &cgrp_dfl_root) |
9ccece80 | 2420 | return 0; |
e8c82d20 | 2421 | |
e8c82d20 | 2422 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 2423 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
2424 | struct cgroup *cgrp = css->cgroup; |
2425 | ||
e8c82d20 LZ |
2426 | if (cgroup_is_dead(cgrp)) |
2427 | continue; | |
2428 | ||
21a2d343 | 2429 | ret = cgroup_addrm_files(cgrp, cfts, is_add); |
9ccece80 TH |
2430 | if (ret) |
2431 | break; | |
8e3f6541 | 2432 | } |
21a2d343 TH |
2433 | |
2434 | if (is_add && !ret) | |
2435 | kernfs_activate(root->kn); | |
9ccece80 | 2436 | return ret; |
8e3f6541 TH |
2437 | } |
2438 | ||
2da440a2 | 2439 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 2440 | { |
2bb566cb | 2441 | struct cftype *cft; |
8e3f6541 | 2442 | |
2bd59d48 TH |
2443 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
2444 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
2445 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
2446 | kfree(cft->kf_ops); | |
2447 | cft->kf_ops = NULL; | |
2da440a2 | 2448 | cft->ss = NULL; |
2bd59d48 | 2449 | } |
2da440a2 TH |
2450 | } |
2451 | ||
2bd59d48 | 2452 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
2453 | { |
2454 | struct cftype *cft; | |
2455 | ||
2bd59d48 TH |
2456 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
2457 | struct kernfs_ops *kf_ops; | |
2458 | ||
0adb0704 TH |
2459 | WARN_ON(cft->ss || cft->kf_ops); |
2460 | ||
2bd59d48 TH |
2461 | if (cft->seq_start) |
2462 | kf_ops = &cgroup_kf_ops; | |
2463 | else | |
2464 | kf_ops = &cgroup_kf_single_ops; | |
2465 | ||
2466 | /* | |
2467 | * Ugh... if @cft wants a custom max_write_len, we need to | |
2468 | * make a copy of kf_ops to set its atomic_write_len. | |
2469 | */ | |
2470 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
2471 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
2472 | if (!kf_ops) { | |
2473 | cgroup_exit_cftypes(cfts); | |
2474 | return -ENOMEM; | |
2475 | } | |
2476 | kf_ops->atomic_write_len = cft->max_write_len; | |
2477 | } | |
8e3f6541 | 2478 | |
2bd59d48 | 2479 | cft->kf_ops = kf_ops; |
2bb566cb | 2480 | cft->ss = ss; |
2bd59d48 | 2481 | } |
2bb566cb | 2482 | |
2bd59d48 | 2483 | return 0; |
2da440a2 TH |
2484 | } |
2485 | ||
21a2d343 TH |
2486 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
2487 | { | |
2488 | lockdep_assert_held(&cgroup_tree_mutex); | |
2489 | ||
2490 | if (!cfts || !cfts[0].ss) | |
2491 | return -ENOENT; | |
2492 | ||
2493 | list_del(&cfts->node); | |
2494 | cgroup_apply_cftypes(cfts, false); | |
2495 | cgroup_exit_cftypes(cfts); | |
2496 | return 0; | |
8e3f6541 | 2497 | } |
8e3f6541 | 2498 | |
79578621 TH |
2499 | /** |
2500 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
2501 | * @cfts: zero-length name terminated array of cftypes |
2502 | * | |
2bb566cb TH |
2503 | * Unregister @cfts. Files described by @cfts are removed from all |
2504 | * existing cgroups and all future cgroups won't have them either. This | |
2505 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
2506 | * |
2507 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 2508 | * registered. |
79578621 | 2509 | */ |
2bb566cb | 2510 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 2511 | { |
21a2d343 | 2512 | int ret; |
79578621 | 2513 | |
21a2d343 TH |
2514 | mutex_lock(&cgroup_tree_mutex); |
2515 | ret = cgroup_rm_cftypes_locked(cfts); | |
2516 | mutex_unlock(&cgroup_tree_mutex); | |
2517 | return ret; | |
80b13586 TH |
2518 | } |
2519 | ||
8e3f6541 TH |
2520 | /** |
2521 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2522 | * @ss: target cgroup subsystem | |
2523 | * @cfts: zero-length name terminated array of cftypes | |
2524 | * | |
2525 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2526 | * existing cgroups to which @ss is attached and all future cgroups will | |
2527 | * have them too. This function can be called anytime whether @ss is | |
2528 | * attached or not. | |
2529 | * | |
2530 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2531 | * function currently returns 0 as long as @cfts registration is successful | |
2532 | * even if some file creation attempts on existing cgroups fail. | |
2533 | */ | |
03b1cde6 | 2534 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 2535 | { |
9ccece80 | 2536 | int ret; |
8e3f6541 | 2537 | |
dc5736ed LZ |
2538 | if (!cfts || cfts[0].name[0] == '\0') |
2539 | return 0; | |
2bb566cb | 2540 | |
2bd59d48 TH |
2541 | ret = cgroup_init_cftypes(ss, cfts); |
2542 | if (ret) | |
2543 | return ret; | |
79578621 | 2544 | |
21a2d343 TH |
2545 | mutex_lock(&cgroup_tree_mutex); |
2546 | ||
0adb0704 | 2547 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 2548 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 2549 | if (ret) |
21a2d343 | 2550 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 2551 | |
21a2d343 | 2552 | mutex_unlock(&cgroup_tree_mutex); |
9ccece80 | 2553 | return ret; |
79578621 TH |
2554 | } |
2555 | ||
a043e3b2 LZ |
2556 | /** |
2557 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2558 | * @cgrp: the cgroup in question | |
2559 | * | |
2560 | * Return the number of tasks in the cgroup. | |
2561 | */ | |
07bc356e | 2562 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2563 | { |
2564 | int count = 0; | |
69d0206c | 2565 | struct cgrp_cset_link *link; |
817929ec | 2566 | |
96d365e0 | 2567 | down_read(&css_set_rwsem); |
69d0206c TH |
2568 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
2569 | count += atomic_read(&link->cset->refcount); | |
96d365e0 | 2570 | up_read(&css_set_rwsem); |
bbcb81d0 PM |
2571 | return count; |
2572 | } | |
2573 | ||
53fa5261 | 2574 | /** |
492eb21b TH |
2575 | * css_next_child - find the next child of a given css |
2576 | * @pos_css: the current position (%NULL to initiate traversal) | |
2577 | * @parent_css: css whose children to walk | |
53fa5261 | 2578 | * |
492eb21b | 2579 | * This function returns the next child of @parent_css and should be called |
87fb54f1 TH |
2580 | * under either cgroup_mutex or RCU read lock. The only requirement is |
2581 | * that @parent_css and @pos_css are accessible. The next sibling is | |
2582 | * guaranteed to be returned regardless of their states. | |
53fa5261 | 2583 | */ |
492eb21b TH |
2584 | struct cgroup_subsys_state * |
2585 | css_next_child(struct cgroup_subsys_state *pos_css, | |
2586 | struct cgroup_subsys_state *parent_css) | |
53fa5261 | 2587 | { |
492eb21b TH |
2588 | struct cgroup *pos = pos_css ? pos_css->cgroup : NULL; |
2589 | struct cgroup *cgrp = parent_css->cgroup; | |
53fa5261 TH |
2590 | struct cgroup *next; |
2591 | ||
ace2bee8 | 2592 | cgroup_assert_mutexes_or_rcu_locked(); |
53fa5261 TH |
2593 | |
2594 | /* | |
2595 | * @pos could already have been removed. Once a cgroup is removed, | |
2596 | * its ->sibling.next is no longer updated when its next sibling | |
ea15f8cc TH |
2597 | * changes. As CGRP_DEAD assertion is serialized and happens |
2598 | * before the cgroup is taken off the ->sibling list, if we see it | |
2599 | * unasserted, it's guaranteed that the next sibling hasn't | |
2600 | * finished its grace period even if it's already removed, and thus | |
2601 | * safe to dereference from this RCU critical section. If | |
2602 | * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed | |
2603 | * to be visible as %true here. | |
3b287a50 TH |
2604 | * |
2605 | * If @pos is dead, its next pointer can't be dereferenced; | |
2606 | * however, as each cgroup is given a monotonically increasing | |
2607 | * unique serial number and always appended to the sibling list, | |
2608 | * the next one can be found by walking the parent's children until | |
2609 | * we see a cgroup with higher serial number than @pos's. While | |
2610 | * this path can be slower, it's taken only when either the current | |
2611 | * cgroup is removed or iteration and removal race. | |
53fa5261 | 2612 | */ |
3b287a50 TH |
2613 | if (!pos) { |
2614 | next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling); | |
2615 | } else if (likely(!cgroup_is_dead(pos))) { | |
53fa5261 | 2616 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); |
3b287a50 TH |
2617 | } else { |
2618 | list_for_each_entry_rcu(next, &cgrp->children, sibling) | |
2619 | if (next->serial_nr > pos->serial_nr) | |
2620 | break; | |
53fa5261 TH |
2621 | } |
2622 | ||
492eb21b TH |
2623 | if (&next->sibling == &cgrp->children) |
2624 | return NULL; | |
2625 | ||
ca8bdcaf | 2626 | return cgroup_css(next, parent_css->ss); |
53fa5261 | 2627 | } |
53fa5261 | 2628 | |
574bd9f7 | 2629 | /** |
492eb21b | 2630 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 2631 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 2632 | * @root: css whose descendants to walk |
574bd9f7 | 2633 | * |
492eb21b | 2634 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
2635 | * to visit for pre-order traversal of @root's descendants. @root is |
2636 | * included in the iteration and the first node to be visited. | |
75501a6d | 2637 | * |
87fb54f1 TH |
2638 | * While this function requires cgroup_mutex or RCU read locking, it |
2639 | * doesn't require the whole traversal to be contained in a single critical | |
2640 | * section. This function will return the correct next descendant as long | |
2641 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
574bd9f7 | 2642 | */ |
492eb21b TH |
2643 | struct cgroup_subsys_state * |
2644 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
2645 | struct cgroup_subsys_state *root) | |
574bd9f7 | 2646 | { |
492eb21b | 2647 | struct cgroup_subsys_state *next; |
574bd9f7 | 2648 | |
ace2bee8 | 2649 | cgroup_assert_mutexes_or_rcu_locked(); |
574bd9f7 | 2650 | |
bd8815a6 | 2651 | /* if first iteration, visit @root */ |
7805d000 | 2652 | if (!pos) |
bd8815a6 | 2653 | return root; |
574bd9f7 TH |
2654 | |
2655 | /* visit the first child if exists */ | |
492eb21b | 2656 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
2657 | if (next) |
2658 | return next; | |
2659 | ||
2660 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b TH |
2661 | while (pos != root) { |
2662 | next = css_next_child(pos, css_parent(pos)); | |
75501a6d | 2663 | if (next) |
574bd9f7 | 2664 | return next; |
492eb21b | 2665 | pos = css_parent(pos); |
7805d000 | 2666 | } |
574bd9f7 TH |
2667 | |
2668 | return NULL; | |
2669 | } | |
574bd9f7 | 2670 | |
12a9d2fe | 2671 | /** |
492eb21b TH |
2672 | * css_rightmost_descendant - return the rightmost descendant of a css |
2673 | * @pos: css of interest | |
12a9d2fe | 2674 | * |
492eb21b TH |
2675 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
2676 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 2677 | * subtree of @pos. |
75501a6d | 2678 | * |
87fb54f1 TH |
2679 | * While this function requires cgroup_mutex or RCU read locking, it |
2680 | * doesn't require the whole traversal to be contained in a single critical | |
2681 | * section. This function will return the correct rightmost descendant as | |
2682 | * long as @pos is accessible. | |
12a9d2fe | 2683 | */ |
492eb21b TH |
2684 | struct cgroup_subsys_state * |
2685 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 2686 | { |
492eb21b | 2687 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 2688 | |
ace2bee8 | 2689 | cgroup_assert_mutexes_or_rcu_locked(); |
12a9d2fe TH |
2690 | |
2691 | do { | |
2692 | last = pos; | |
2693 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
2694 | pos = NULL; | |
492eb21b | 2695 | css_for_each_child(tmp, last) |
12a9d2fe TH |
2696 | pos = tmp; |
2697 | } while (pos); | |
2698 | ||
2699 | return last; | |
2700 | } | |
12a9d2fe | 2701 | |
492eb21b TH |
2702 | static struct cgroup_subsys_state * |
2703 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 2704 | { |
492eb21b | 2705 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
2706 | |
2707 | do { | |
2708 | last = pos; | |
492eb21b | 2709 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
2710 | } while (pos); |
2711 | ||
2712 | return last; | |
2713 | } | |
2714 | ||
2715 | /** | |
492eb21b | 2716 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 2717 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 2718 | * @root: css whose descendants to walk |
574bd9f7 | 2719 | * |
492eb21b | 2720 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
2721 | * to visit for post-order traversal of @root's descendants. @root is |
2722 | * included in the iteration and the last node to be visited. | |
75501a6d | 2723 | * |
87fb54f1 TH |
2724 | * While this function requires cgroup_mutex or RCU read locking, it |
2725 | * doesn't require the whole traversal to be contained in a single critical | |
2726 | * section. This function will return the correct next descendant as long | |
2727 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
2728 | * @cgroup. | |
574bd9f7 | 2729 | */ |
492eb21b TH |
2730 | struct cgroup_subsys_state * |
2731 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
2732 | struct cgroup_subsys_state *root) | |
574bd9f7 | 2733 | { |
492eb21b | 2734 | struct cgroup_subsys_state *next; |
574bd9f7 | 2735 | |
ace2bee8 | 2736 | cgroup_assert_mutexes_or_rcu_locked(); |
574bd9f7 | 2737 | |
58b79a91 TH |
2738 | /* if first iteration, visit leftmost descendant which may be @root */ |
2739 | if (!pos) | |
2740 | return css_leftmost_descendant(root); | |
574bd9f7 | 2741 | |
bd8815a6 TH |
2742 | /* if we visited @root, we're done */ |
2743 | if (pos == root) | |
2744 | return NULL; | |
2745 | ||
574bd9f7 | 2746 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
492eb21b | 2747 | next = css_next_child(pos, css_parent(pos)); |
75501a6d | 2748 | if (next) |
492eb21b | 2749 | return css_leftmost_descendant(next); |
574bd9f7 TH |
2750 | |
2751 | /* no sibling left, visit parent */ | |
bd8815a6 | 2752 | return css_parent(pos); |
574bd9f7 | 2753 | } |
574bd9f7 | 2754 | |
0942eeee | 2755 | /** |
72ec7029 | 2756 | * css_advance_task_iter - advance a task itererator to the next css_set |
0942eeee TH |
2757 | * @it: the iterator to advance |
2758 | * | |
2759 | * Advance @it to the next css_set to walk. | |
d515876e | 2760 | */ |
72ec7029 | 2761 | static void css_advance_task_iter(struct css_task_iter *it) |
d515876e TH |
2762 | { |
2763 | struct list_head *l = it->cset_link; | |
2764 | struct cgrp_cset_link *link; | |
2765 | struct css_set *cset; | |
2766 | ||
2767 | /* Advance to the next non-empty css_set */ | |
2768 | do { | |
2769 | l = l->next; | |
72ec7029 | 2770 | if (l == &it->origin_css->cgroup->cset_links) { |
d515876e TH |
2771 | it->cset_link = NULL; |
2772 | return; | |
2773 | } | |
2774 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
2775 | cset = link->cset; | |
c7561128 TH |
2776 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); |
2777 | ||
d515876e | 2778 | it->cset_link = l; |
c7561128 TH |
2779 | |
2780 | if (!list_empty(&cset->tasks)) | |
2781 | it->task = cset->tasks.next; | |
2782 | else | |
2783 | it->task = cset->mg_tasks.next; | |
d515876e TH |
2784 | } |
2785 | ||
0942eeee | 2786 | /** |
72ec7029 TH |
2787 | * css_task_iter_start - initiate task iteration |
2788 | * @css: the css to walk tasks of | |
0942eeee TH |
2789 | * @it: the task iterator to use |
2790 | * | |
72ec7029 TH |
2791 | * Initiate iteration through the tasks of @css. The caller can call |
2792 | * css_task_iter_next() to walk through the tasks until the function | |
2793 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
2794 | * called. | |
0942eeee TH |
2795 | * |
2796 | * Note that this function acquires a lock which is released when the | |
2797 | * iteration finishes. The caller can't sleep while iteration is in | |
2798 | * progress. | |
2799 | */ | |
72ec7029 TH |
2800 | void css_task_iter_start(struct cgroup_subsys_state *css, |
2801 | struct css_task_iter *it) | |
96d365e0 | 2802 | __acquires(css_set_rwsem) |
817929ec | 2803 | { |
56fde9e0 TH |
2804 | /* no one should try to iterate before mounting cgroups */ |
2805 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 2806 | |
96d365e0 | 2807 | down_read(&css_set_rwsem); |
c59cd3d8 | 2808 | |
72ec7029 TH |
2809 | it->origin_css = css; |
2810 | it->cset_link = &css->cgroup->cset_links; | |
c59cd3d8 | 2811 | |
72ec7029 | 2812 | css_advance_task_iter(it); |
817929ec PM |
2813 | } |
2814 | ||
0942eeee | 2815 | /** |
72ec7029 | 2816 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
2817 | * @it: the task iterator being iterated |
2818 | * | |
2819 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
2820 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
2821 | * reaches the end. | |
0942eeee | 2822 | */ |
72ec7029 | 2823 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec PM |
2824 | { |
2825 | struct task_struct *res; | |
2826 | struct list_head *l = it->task; | |
c7561128 TH |
2827 | struct cgrp_cset_link *link = list_entry(it->cset_link, |
2828 | struct cgrp_cset_link, cset_link); | |
817929ec PM |
2829 | |
2830 | /* If the iterator cg is NULL, we have no tasks */ | |
69d0206c | 2831 | if (!it->cset_link) |
817929ec PM |
2832 | return NULL; |
2833 | res = list_entry(l, struct task_struct, cg_list); | |
c7561128 TH |
2834 | |
2835 | /* | |
2836 | * Advance iterator to find next entry. cset->tasks is consumed | |
2837 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
2838 | * next cset. | |
2839 | */ | |
817929ec | 2840 | l = l->next; |
c7561128 TH |
2841 | |
2842 | if (l == &link->cset->tasks) | |
2843 | l = link->cset->mg_tasks.next; | |
2844 | ||
2845 | if (l == &link->cset->mg_tasks) | |
72ec7029 | 2846 | css_advance_task_iter(it); |
c7561128 | 2847 | else |
817929ec | 2848 | it->task = l; |
c7561128 | 2849 | |
817929ec PM |
2850 | return res; |
2851 | } | |
2852 | ||
0942eeee | 2853 | /** |
72ec7029 | 2854 | * css_task_iter_end - finish task iteration |
0942eeee TH |
2855 | * @it: the task iterator to finish |
2856 | * | |
72ec7029 | 2857 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 2858 | */ |
72ec7029 | 2859 | void css_task_iter_end(struct css_task_iter *it) |
96d365e0 | 2860 | __releases(css_set_rwsem) |
31a7df01 | 2861 | { |
96d365e0 | 2862 | up_read(&css_set_rwsem); |
31a7df01 CW |
2863 | } |
2864 | ||
2865 | /** | |
8cc99345 TH |
2866 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
2867 | * @to: cgroup to which the tasks will be moved | |
2868 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 2869 | * |
eaf797ab TH |
2870 | * Locking rules between cgroup_post_fork() and the migration path |
2871 | * guarantee that, if a task is forking while being migrated, the new child | |
2872 | * is guaranteed to be either visible in the source cgroup after the | |
2873 | * parent's migration is complete or put into the target cgroup. No task | |
2874 | * can slip out of migration through forking. | |
31a7df01 | 2875 | */ |
8cc99345 | 2876 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 2877 | { |
952aaa12 TH |
2878 | LIST_HEAD(preloaded_csets); |
2879 | struct cgrp_cset_link *link; | |
72ec7029 | 2880 | struct css_task_iter it; |
e406d1cf | 2881 | struct task_struct *task; |
952aaa12 | 2882 | int ret; |
31a7df01 | 2883 | |
952aaa12 | 2884 | mutex_lock(&cgroup_mutex); |
31a7df01 | 2885 | |
952aaa12 TH |
2886 | /* all tasks in @from are being moved, all csets are source */ |
2887 | down_read(&css_set_rwsem); | |
2888 | list_for_each_entry(link, &from->cset_links, cset_link) | |
2889 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
2890 | up_read(&css_set_rwsem); | |
31a7df01 | 2891 | |
952aaa12 TH |
2892 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
2893 | if (ret) | |
2894 | goto out_err; | |
8cc99345 | 2895 | |
952aaa12 TH |
2896 | /* |
2897 | * Migrate tasks one-by-one until @form is empty. This fails iff | |
2898 | * ->can_attach() fails. | |
2899 | */ | |
e406d1cf TH |
2900 | do { |
2901 | css_task_iter_start(&from->dummy_css, &it); | |
2902 | task = css_task_iter_next(&it); | |
2903 | if (task) | |
2904 | get_task_struct(task); | |
2905 | css_task_iter_end(&it); | |
2906 | ||
2907 | if (task) { | |
952aaa12 | 2908 | ret = cgroup_migrate(to, task, false); |
e406d1cf TH |
2909 | put_task_struct(task); |
2910 | } | |
2911 | } while (task && !ret); | |
952aaa12 TH |
2912 | out_err: |
2913 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 2914 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 2915 | return ret; |
8cc99345 TH |
2916 | } |
2917 | ||
bbcb81d0 | 2918 | /* |
102a775e | 2919 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
2920 | * |
2921 | * Reading this file can return large amounts of data if a cgroup has | |
2922 | * *lots* of attached tasks. So it may need several calls to read(), | |
2923 | * but we cannot guarantee that the information we produce is correct | |
2924 | * unless we produce it entirely atomically. | |
2925 | * | |
bbcb81d0 | 2926 | */ |
bbcb81d0 | 2927 | |
24528255 LZ |
2928 | /* which pidlist file are we talking about? */ |
2929 | enum cgroup_filetype { | |
2930 | CGROUP_FILE_PROCS, | |
2931 | CGROUP_FILE_TASKS, | |
2932 | }; | |
2933 | ||
2934 | /* | |
2935 | * A pidlist is a list of pids that virtually represents the contents of one | |
2936 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
2937 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
2938 | * to the cgroup. | |
2939 | */ | |
2940 | struct cgroup_pidlist { | |
2941 | /* | |
2942 | * used to find which pidlist is wanted. doesn't change as long as | |
2943 | * this particular list stays in the list. | |
2944 | */ | |
2945 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
2946 | /* array of xids */ | |
2947 | pid_t *list; | |
2948 | /* how many elements the above list has */ | |
2949 | int length; | |
24528255 LZ |
2950 | /* each of these stored in a list by its cgroup */ |
2951 | struct list_head links; | |
2952 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
2953 | struct cgroup *owner; | |
b1a21367 TH |
2954 | /* for delayed destruction */ |
2955 | struct delayed_work destroy_dwork; | |
24528255 LZ |
2956 | }; |
2957 | ||
d1d9fd33 BB |
2958 | /* |
2959 | * The following two functions "fix" the issue where there are more pids | |
2960 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
2961 | * TODO: replace with a kernel-wide solution to this problem | |
2962 | */ | |
2963 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
2964 | static void *pidlist_allocate(int count) | |
2965 | { | |
2966 | if (PIDLIST_TOO_LARGE(count)) | |
2967 | return vmalloc(count * sizeof(pid_t)); | |
2968 | else | |
2969 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
2970 | } | |
b1a21367 | 2971 | |
d1d9fd33 BB |
2972 | static void pidlist_free(void *p) |
2973 | { | |
2974 | if (is_vmalloc_addr(p)) | |
2975 | vfree(p); | |
2976 | else | |
2977 | kfree(p); | |
2978 | } | |
d1d9fd33 | 2979 | |
b1a21367 TH |
2980 | /* |
2981 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
2982 | * should be left afterwards. | |
2983 | */ | |
2984 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
2985 | { | |
2986 | struct cgroup_pidlist *l, *tmp_l; | |
2987 | ||
2988 | mutex_lock(&cgrp->pidlist_mutex); | |
2989 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
2990 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
2991 | mutex_unlock(&cgrp->pidlist_mutex); | |
2992 | ||
2993 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
2994 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
2995 | } | |
2996 | ||
2997 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
2998 | { | |
2999 | struct delayed_work *dwork = to_delayed_work(work); | |
3000 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
3001 | destroy_dwork); | |
3002 | struct cgroup_pidlist *tofree = NULL; | |
3003 | ||
3004 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
3005 | |
3006 | /* | |
04502365 TH |
3007 | * Destroy iff we didn't get queued again. The state won't change |
3008 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 3009 | */ |
04502365 | 3010 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
3011 | list_del(&l->links); |
3012 | pidlist_free(l->list); | |
3013 | put_pid_ns(l->key.ns); | |
3014 | tofree = l; | |
3015 | } | |
3016 | ||
b1a21367 TH |
3017 | mutex_unlock(&l->owner->pidlist_mutex); |
3018 | kfree(tofree); | |
3019 | } | |
3020 | ||
bbcb81d0 | 3021 | /* |
102a775e | 3022 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 3023 | * Returns the number of unique elements. |
bbcb81d0 | 3024 | */ |
6ee211ad | 3025 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 3026 | { |
102a775e | 3027 | int src, dest = 1; |
102a775e BB |
3028 | |
3029 | /* | |
3030 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3031 | * edge cases first; no work needs to be done for either | |
3032 | */ | |
3033 | if (length == 0 || length == 1) | |
3034 | return length; | |
3035 | /* src and dest walk down the list; dest counts unique elements */ | |
3036 | for (src = 1; src < length; src++) { | |
3037 | /* find next unique element */ | |
3038 | while (list[src] == list[src-1]) { | |
3039 | src++; | |
3040 | if (src == length) | |
3041 | goto after; | |
3042 | } | |
3043 | /* dest always points to where the next unique element goes */ | |
3044 | list[dest] = list[src]; | |
3045 | dest++; | |
3046 | } | |
3047 | after: | |
102a775e BB |
3048 | return dest; |
3049 | } | |
3050 | ||
afb2bc14 TH |
3051 | /* |
3052 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
3053 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
3054 | * different per namespace, each namespace needs differently sorted list, | |
3055 | * making it impossible to use, for example, single rbtree of member tasks | |
3056 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
3057 | * per open file is dangerous, so cgroup had to implement shared pool of | |
3058 | * pidlists keyed by cgroup and namespace. | |
3059 | * | |
3060 | * All this extra complexity was caused by the original implementation | |
3061 | * committing to an entirely unnecessary property. In the long term, we | |
3062 | * want to do away with it. Explicitly scramble sort order if | |
3063 | * sane_behavior so that no such expectation exists in the new interface. | |
3064 | * | |
3065 | * Scrambling is done by swapping every two consecutive bits, which is | |
3066 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
3067 | */ | |
3068 | static pid_t pid_fry(pid_t pid) | |
3069 | { | |
3070 | unsigned a = pid & 0x55555555; | |
3071 | unsigned b = pid & 0xAAAAAAAA; | |
3072 | ||
3073 | return (a << 1) | (b >> 1); | |
3074 | } | |
3075 | ||
3076 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
3077 | { | |
3078 | if (cgroup_sane_behavior(cgrp)) | |
3079 | return pid_fry(pid); | |
3080 | else | |
3081 | return pid; | |
3082 | } | |
3083 | ||
102a775e BB |
3084 | static int cmppid(const void *a, const void *b) |
3085 | { | |
3086 | return *(pid_t *)a - *(pid_t *)b; | |
3087 | } | |
3088 | ||
afb2bc14 TH |
3089 | static int fried_cmppid(const void *a, const void *b) |
3090 | { | |
3091 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
3092 | } | |
3093 | ||
e6b81710 TH |
3094 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
3095 | enum cgroup_filetype type) | |
3096 | { | |
3097 | struct cgroup_pidlist *l; | |
3098 | /* don't need task_nsproxy() if we're looking at ourself */ | |
3099 | struct pid_namespace *ns = task_active_pid_ns(current); | |
3100 | ||
3101 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
3102 | ||
3103 | list_for_each_entry(l, &cgrp->pidlists, links) | |
3104 | if (l->key.type == type && l->key.ns == ns) | |
3105 | return l; | |
3106 | return NULL; | |
3107 | } | |
3108 | ||
72a8cb30 BB |
3109 | /* |
3110 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3111 | * returns with the lock on that pidlist already held, and takes care | |
3112 | * of the use count, or returns NULL with no locks held if we're out of | |
3113 | * memory. | |
3114 | */ | |
e6b81710 TH |
3115 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
3116 | enum cgroup_filetype type) | |
72a8cb30 BB |
3117 | { |
3118 | struct cgroup_pidlist *l; | |
b70cc5fd | 3119 | |
e6b81710 TH |
3120 | lockdep_assert_held(&cgrp->pidlist_mutex); |
3121 | ||
3122 | l = cgroup_pidlist_find(cgrp, type); | |
3123 | if (l) | |
3124 | return l; | |
3125 | ||
72a8cb30 | 3126 | /* entry not found; create a new one */ |
f4f4be2b | 3127 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 3128 | if (!l) |
72a8cb30 | 3129 | return l; |
e6b81710 | 3130 | |
b1a21367 | 3131 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 3132 | l->key.type = type; |
e6b81710 TH |
3133 | /* don't need task_nsproxy() if we're looking at ourself */ |
3134 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
3135 | l->owner = cgrp; |
3136 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
3137 | return l; |
3138 | } | |
3139 | ||
102a775e BB |
3140 | /* |
3141 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3142 | */ | |
72a8cb30 BB |
3143 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3144 | struct cgroup_pidlist **lp) | |
102a775e BB |
3145 | { |
3146 | pid_t *array; | |
3147 | int length; | |
3148 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 3149 | struct css_task_iter it; |
817929ec | 3150 | struct task_struct *tsk; |
102a775e BB |
3151 | struct cgroup_pidlist *l; |
3152 | ||
4bac00d1 TH |
3153 | lockdep_assert_held(&cgrp->pidlist_mutex); |
3154 | ||
102a775e BB |
3155 | /* |
3156 | * If cgroup gets more users after we read count, we won't have | |
3157 | * enough space - tough. This race is indistinguishable to the | |
3158 | * caller from the case that the additional cgroup users didn't | |
3159 | * show up until sometime later on. | |
3160 | */ | |
3161 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3162 | array = pidlist_allocate(length); |
102a775e BB |
3163 | if (!array) |
3164 | return -ENOMEM; | |
3165 | /* now, populate the array */ | |
72ec7029 TH |
3166 | css_task_iter_start(&cgrp->dummy_css, &it); |
3167 | while ((tsk = css_task_iter_next(&it))) { | |
102a775e | 3168 | if (unlikely(n == length)) |
817929ec | 3169 | break; |
102a775e | 3170 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3171 | if (type == CGROUP_FILE_PROCS) |
3172 | pid = task_tgid_vnr(tsk); | |
3173 | else | |
3174 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3175 | if (pid > 0) /* make sure to only use valid results */ |
3176 | array[n++] = pid; | |
817929ec | 3177 | } |
72ec7029 | 3178 | css_task_iter_end(&it); |
102a775e BB |
3179 | length = n; |
3180 | /* now sort & (if procs) strip out duplicates */ | |
afb2bc14 TH |
3181 | if (cgroup_sane_behavior(cgrp)) |
3182 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); | |
3183 | else | |
3184 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3185 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 3186 | length = pidlist_uniq(array, length); |
e6b81710 | 3187 | |
e6b81710 | 3188 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 3189 | if (!l) { |
e6b81710 | 3190 | mutex_unlock(&cgrp->pidlist_mutex); |
d1d9fd33 | 3191 | pidlist_free(array); |
72a8cb30 | 3192 | return -ENOMEM; |
102a775e | 3193 | } |
e6b81710 TH |
3194 | |
3195 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 3196 | pidlist_free(l->list); |
102a775e BB |
3197 | l->list = array; |
3198 | l->length = length; | |
72a8cb30 | 3199 | *lp = l; |
102a775e | 3200 | return 0; |
bbcb81d0 PM |
3201 | } |
3202 | ||
846c7bb0 | 3203 | /** |
a043e3b2 | 3204 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3205 | * @stats: cgroupstats to fill information into |
3206 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3207 | * been requested. | |
a043e3b2 LZ |
3208 | * |
3209 | * Build and fill cgroupstats so that taskstats can export it to user | |
3210 | * space. | |
846c7bb0 BS |
3211 | */ |
3212 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3213 | { | |
2bd59d48 | 3214 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 3215 | struct cgroup *cgrp; |
72ec7029 | 3216 | struct css_task_iter it; |
846c7bb0 | 3217 | struct task_struct *tsk; |
33d283be | 3218 | |
2bd59d48 TH |
3219 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
3220 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
3221 | kernfs_type(kn) != KERNFS_DIR) | |
3222 | return -EINVAL; | |
3223 | ||
bad34660 LZ |
3224 | mutex_lock(&cgroup_mutex); |
3225 | ||
846c7bb0 | 3226 | /* |
2bd59d48 TH |
3227 | * We aren't being called from kernfs and there's no guarantee on |
3228 | * @kn->priv's validity. For this and css_tryget_from_dir(), | |
3229 | * @kn->priv is RCU safe. Let's do the RCU dancing. | |
846c7bb0 | 3230 | */ |
2bd59d48 TH |
3231 | rcu_read_lock(); |
3232 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 3233 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 3234 | rcu_read_unlock(); |
bad34660 | 3235 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
3236 | return -ENOENT; |
3237 | } | |
bad34660 | 3238 | rcu_read_unlock(); |
846c7bb0 | 3239 | |
72ec7029 TH |
3240 | css_task_iter_start(&cgrp->dummy_css, &it); |
3241 | while ((tsk = css_task_iter_next(&it))) { | |
846c7bb0 BS |
3242 | switch (tsk->state) { |
3243 | case TASK_RUNNING: | |
3244 | stats->nr_running++; | |
3245 | break; | |
3246 | case TASK_INTERRUPTIBLE: | |
3247 | stats->nr_sleeping++; | |
3248 | break; | |
3249 | case TASK_UNINTERRUPTIBLE: | |
3250 | stats->nr_uninterruptible++; | |
3251 | break; | |
3252 | case TASK_STOPPED: | |
3253 | stats->nr_stopped++; | |
3254 | break; | |
3255 | default: | |
3256 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3257 | stats->nr_io_wait++; | |
3258 | break; | |
3259 | } | |
3260 | } | |
72ec7029 | 3261 | css_task_iter_end(&it); |
846c7bb0 | 3262 | |
bad34660 | 3263 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 3264 | return 0; |
846c7bb0 BS |
3265 | } |
3266 | ||
8f3ff208 | 3267 | |
bbcb81d0 | 3268 | /* |
102a775e | 3269 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3270 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3271 | * in the cgroup->l->list array. |
bbcb81d0 | 3272 | */ |
cc31edce | 3273 | |
102a775e | 3274 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3275 | { |
cc31edce PM |
3276 | /* |
3277 | * Initially we receive a position value that corresponds to | |
3278 | * one more than the last pid shown (or 0 on the first call or | |
3279 | * after a seek to the start). Use a binary-search to find the | |
3280 | * next pid to display, if any | |
3281 | */ | |
2bd59d48 | 3282 | struct kernfs_open_file *of = s->private; |
7da11279 | 3283 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 3284 | struct cgroup_pidlist *l; |
7da11279 | 3285 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 3286 | int index = 0, pid = *pos; |
4bac00d1 TH |
3287 | int *iter, ret; |
3288 | ||
3289 | mutex_lock(&cgrp->pidlist_mutex); | |
3290 | ||
3291 | /* | |
5d22444f | 3292 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 3293 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 3294 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
3295 | * could already have been destroyed. |
3296 | */ | |
5d22444f TH |
3297 | if (of->priv) |
3298 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
3299 | |
3300 | /* | |
3301 | * Either this is the first start() after open or the matching | |
3302 | * pidlist has been destroyed inbetween. Create a new one. | |
3303 | */ | |
5d22444f TH |
3304 | if (!of->priv) { |
3305 | ret = pidlist_array_load(cgrp, type, | |
3306 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
3307 | if (ret) |
3308 | return ERR_PTR(ret); | |
3309 | } | |
5d22444f | 3310 | l = of->priv; |
cc31edce | 3311 | |
cc31edce | 3312 | if (pid) { |
102a775e | 3313 | int end = l->length; |
20777766 | 3314 | |
cc31edce PM |
3315 | while (index < end) { |
3316 | int mid = (index + end) / 2; | |
afb2bc14 | 3317 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
3318 | index = mid; |
3319 | break; | |
afb2bc14 | 3320 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
3321 | index = mid + 1; |
3322 | else | |
3323 | end = mid; | |
3324 | } | |
3325 | } | |
3326 | /* If we're off the end of the array, we're done */ | |
102a775e | 3327 | if (index >= l->length) |
cc31edce PM |
3328 | return NULL; |
3329 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3330 | iter = l->list + index; |
afb2bc14 | 3331 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
3332 | return iter; |
3333 | } | |
3334 | ||
102a775e | 3335 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3336 | { |
2bd59d48 | 3337 | struct kernfs_open_file *of = s->private; |
5d22444f | 3338 | struct cgroup_pidlist *l = of->priv; |
62236858 | 3339 | |
5d22444f TH |
3340 | if (l) |
3341 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 3342 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 3343 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
3344 | } |
3345 | ||
102a775e | 3346 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3347 | { |
2bd59d48 | 3348 | struct kernfs_open_file *of = s->private; |
5d22444f | 3349 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
3350 | pid_t *p = v; |
3351 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3352 | /* |
3353 | * Advance to the next pid in the array. If this goes off the | |
3354 | * end, we're done | |
3355 | */ | |
3356 | p++; | |
3357 | if (p >= end) { | |
3358 | return NULL; | |
3359 | } else { | |
7da11279 | 3360 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
3361 | return p; |
3362 | } | |
3363 | } | |
3364 | ||
102a775e | 3365 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3366 | { |
3367 | return seq_printf(s, "%d\n", *(int *)v); | |
3368 | } | |
bbcb81d0 | 3369 | |
102a775e BB |
3370 | /* |
3371 | * seq_operations functions for iterating on pidlists through seq_file - | |
3372 | * independent of whether it's tasks or procs | |
3373 | */ | |
3374 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3375 | .start = cgroup_pidlist_start, | |
3376 | .stop = cgroup_pidlist_stop, | |
3377 | .next = cgroup_pidlist_next, | |
3378 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3379 | }; |
3380 | ||
182446d0 TH |
3381 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
3382 | struct cftype *cft) | |
81a6a5cd | 3383 | { |
182446d0 | 3384 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
3385 | } |
3386 | ||
182446d0 TH |
3387 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
3388 | struct cftype *cft, u64 val) | |
6379c106 | 3389 | { |
182446d0 | 3390 | clear_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
6379c106 | 3391 | if (val) |
182446d0 | 3392 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 3393 | else |
182446d0 | 3394 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
3395 | return 0; |
3396 | } | |
3397 | ||
182446d0 TH |
3398 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
3399 | struct cftype *cft) | |
97978e6d | 3400 | { |
182446d0 | 3401 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
3402 | } |
3403 | ||
182446d0 TH |
3404 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
3405 | struct cftype *cft, u64 val) | |
97978e6d DL |
3406 | { |
3407 | if (val) | |
182446d0 | 3408 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 3409 | else |
182446d0 | 3410 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
3411 | return 0; |
3412 | } | |
3413 | ||
d5c56ced | 3414 | static struct cftype cgroup_base_files[] = { |
81a6a5cd | 3415 | { |
d5c56ced | 3416 | .name = "cgroup.procs", |
6612f05b TH |
3417 | .seq_start = cgroup_pidlist_start, |
3418 | .seq_next = cgroup_pidlist_next, | |
3419 | .seq_stop = cgroup_pidlist_stop, | |
3420 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 3421 | .private = CGROUP_FILE_PROCS, |
74a1166d | 3422 | .write_u64 = cgroup_procs_write, |
74a1166d | 3423 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 3424 | }, |
97978e6d DL |
3425 | { |
3426 | .name = "cgroup.clone_children", | |
873fe09e | 3427 | .flags = CFTYPE_INSANE, |
97978e6d DL |
3428 | .read_u64 = cgroup_clone_children_read, |
3429 | .write_u64 = cgroup_clone_children_write, | |
3430 | }, | |
873fe09e TH |
3431 | { |
3432 | .name = "cgroup.sane_behavior", | |
3433 | .flags = CFTYPE_ONLY_ON_ROOT, | |
2da8ca82 | 3434 | .seq_show = cgroup_sane_behavior_show, |
873fe09e | 3435 | }, |
d5c56ced TH |
3436 | |
3437 | /* | |
3438 | * Historical crazy stuff. These don't have "cgroup." prefix and | |
3439 | * don't exist if sane_behavior. If you're depending on these, be | |
3440 | * prepared to be burned. | |
3441 | */ | |
3442 | { | |
3443 | .name = "tasks", | |
3444 | .flags = CFTYPE_INSANE, /* use "procs" instead */ | |
6612f05b TH |
3445 | .seq_start = cgroup_pidlist_start, |
3446 | .seq_next = cgroup_pidlist_next, | |
3447 | .seq_stop = cgroup_pidlist_stop, | |
3448 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 3449 | .private = CGROUP_FILE_TASKS, |
d5c56ced | 3450 | .write_u64 = cgroup_tasks_write, |
d5c56ced TH |
3451 | .mode = S_IRUGO | S_IWUSR, |
3452 | }, | |
3453 | { | |
3454 | .name = "notify_on_release", | |
3455 | .flags = CFTYPE_INSANE, | |
3456 | .read_u64 = cgroup_read_notify_on_release, | |
3457 | .write_u64 = cgroup_write_notify_on_release, | |
3458 | }, | |
6e6ff25b TH |
3459 | { |
3460 | .name = "release_agent", | |
cc5943a7 | 3461 | .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 3462 | .seq_show = cgroup_release_agent_show, |
6e6ff25b | 3463 | .write_string = cgroup_release_agent_write, |
5f469907 | 3464 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 3465 | }, |
db0416b6 | 3466 | { } /* terminate */ |
bbcb81d0 PM |
3467 | }; |
3468 | ||
13af07df | 3469 | /** |
628f7cd4 | 3470 | * cgroup_populate_dir - create subsys files in a cgroup directory |
13af07df | 3471 | * @cgrp: target cgroup |
13af07df | 3472 | * @subsys_mask: mask of the subsystem ids whose files should be added |
bee55099 TH |
3473 | * |
3474 | * On failure, no file is added. | |
13af07df | 3475 | */ |
628f7cd4 | 3476 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
ddbcc7e8 | 3477 | { |
ddbcc7e8 | 3478 | struct cgroup_subsys *ss; |
b420ba7d | 3479 | int i, ret = 0; |
bbcb81d0 | 3480 | |
8e3f6541 | 3481 | /* process cftsets of each subsystem */ |
b420ba7d | 3482 | for_each_subsys(ss, i) { |
0adb0704 | 3483 | struct cftype *cfts; |
b420ba7d TH |
3484 | |
3485 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 3486 | continue; |
8e3f6541 | 3487 | |
0adb0704 TH |
3488 | list_for_each_entry(cfts, &ss->cfts, node) { |
3489 | ret = cgroup_addrm_files(cgrp, cfts, true); | |
bee55099 TH |
3490 | if (ret < 0) |
3491 | goto err; | |
3492 | } | |
ddbcc7e8 | 3493 | } |
ddbcc7e8 | 3494 | return 0; |
bee55099 TH |
3495 | err: |
3496 | cgroup_clear_dir(cgrp, subsys_mask); | |
3497 | return ret; | |
ddbcc7e8 PM |
3498 | } |
3499 | ||
0c21ead1 TH |
3500 | /* |
3501 | * css destruction is four-stage process. | |
3502 | * | |
3503 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
3504 | * Implemented in kill_css(). | |
3505 | * | |
3506 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
3507 | * and thus css_tryget() is guaranteed to fail, the css can be offlined | |
3508 | * by invoking offline_css(). After offlining, the base ref is put. | |
3509 | * Implemented in css_killed_work_fn(). | |
3510 | * | |
3511 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
3512 | * accessors are inside RCU read sections. css_release() schedules the | |
3513 | * RCU callback. | |
3514 | * | |
3515 | * 4. After the grace period, the css can be freed. Implemented in | |
3516 | * css_free_work_fn(). | |
3517 | * | |
3518 | * It is actually hairier because both step 2 and 4 require process context | |
3519 | * and thus involve punting to css->destroy_work adding two additional | |
3520 | * steps to the already complex sequence. | |
3521 | */ | |
35ef10da | 3522 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
3523 | { |
3524 | struct cgroup_subsys_state *css = | |
35ef10da | 3525 | container_of(work, struct cgroup_subsys_state, destroy_work); |
0c21ead1 | 3526 | struct cgroup *cgrp = css->cgroup; |
48ddbe19 | 3527 | |
0ae78e0b TH |
3528 | if (css->parent) |
3529 | css_put(css->parent); | |
3530 | ||
0c21ead1 | 3531 | css->ss->css_free(css); |
2bd59d48 | 3532 | cgroup_put(cgrp); |
48ddbe19 TH |
3533 | } |
3534 | ||
0c21ead1 | 3535 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
3536 | { |
3537 | struct cgroup_subsys_state *css = | |
0c21ead1 | 3538 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 3539 | |
35ef10da | 3540 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 3541 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
3542 | } |
3543 | ||
d3daf28d TH |
3544 | static void css_release(struct percpu_ref *ref) |
3545 | { | |
3546 | struct cgroup_subsys_state *css = | |
3547 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
3548 | ||
01a97140 | 3549 | RCU_INIT_POINTER(css->cgroup->subsys[css->ss->id], NULL); |
0c21ead1 | 3550 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
3551 | } |
3552 | ||
623f926b TH |
3553 | static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss, |
3554 | struct cgroup *cgrp) | |
ddbcc7e8 | 3555 | { |
bd89aabc | 3556 | css->cgroup = cgrp; |
72c97e54 | 3557 | css->ss = ss; |
ddbcc7e8 | 3558 | css->flags = 0; |
0ae78e0b TH |
3559 | |
3560 | if (cgrp->parent) | |
ca8bdcaf | 3561 | css->parent = cgroup_css(cgrp->parent, ss); |
0ae78e0b | 3562 | else |
38b53aba | 3563 | css->flags |= CSS_ROOT; |
48ddbe19 | 3564 | |
ca8bdcaf | 3565 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
3566 | } |
3567 | ||
2a4ac633 | 3568 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 3569 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 3570 | { |
623f926b | 3571 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
3572 | int ret = 0; |
3573 | ||
ace2bee8 | 3574 | lockdep_assert_held(&cgroup_tree_mutex); |
a31f2d3f TH |
3575 | lockdep_assert_held(&cgroup_mutex); |
3576 | ||
92fb9748 | 3577 | if (ss->css_online) |
eb95419b | 3578 | ret = ss->css_online(css); |
ae7f164a | 3579 | if (!ret) { |
eb95419b | 3580 | css->flags |= CSS_ONLINE; |
f20104de | 3581 | css->cgroup->nr_css++; |
aec25020 | 3582 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 3583 | } |
b1929db4 | 3584 | return ret; |
a31f2d3f TH |
3585 | } |
3586 | ||
2a4ac633 | 3587 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 3588 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 3589 | { |
623f926b | 3590 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f | 3591 | |
ace2bee8 | 3592 | lockdep_assert_held(&cgroup_tree_mutex); |
a31f2d3f TH |
3593 | lockdep_assert_held(&cgroup_mutex); |
3594 | ||
3595 | if (!(css->flags & CSS_ONLINE)) | |
3596 | return; | |
3597 | ||
d7eeac19 | 3598 | if (ss->css_offline) |
eb95419b | 3599 | ss->css_offline(css); |
a31f2d3f | 3600 | |
eb95419b | 3601 | css->flags &= ~CSS_ONLINE; |
09a503ea | 3602 | css->cgroup->nr_css--; |
aec25020 | 3603 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], css); |
a31f2d3f TH |
3604 | } |
3605 | ||
c81c925a TH |
3606 | /** |
3607 | * create_css - create a cgroup_subsys_state | |
3608 | * @cgrp: the cgroup new css will be associated with | |
3609 | * @ss: the subsys of new css | |
3610 | * | |
3611 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
3612 | * css is online and installed in @cgrp with all interface files created. | |
3613 | * Returns 0 on success, -errno on failure. | |
3614 | */ | |
3615 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) | |
3616 | { | |
3617 | struct cgroup *parent = cgrp->parent; | |
3618 | struct cgroup_subsys_state *css; | |
3619 | int err; | |
3620 | ||
c81c925a TH |
3621 | lockdep_assert_held(&cgroup_mutex); |
3622 | ||
3623 | css = ss->css_alloc(cgroup_css(parent, ss)); | |
3624 | if (IS_ERR(css)) | |
3625 | return PTR_ERR(css); | |
3626 | ||
3627 | err = percpu_ref_init(&css->refcnt, css_release); | |
3628 | if (err) | |
3eb59ec6 | 3629 | goto err_free_css; |
c81c925a TH |
3630 | |
3631 | init_css(css, ss, cgrp); | |
3632 | ||
aec25020 | 3633 | err = cgroup_populate_dir(cgrp, 1 << ss->id); |
c81c925a | 3634 | if (err) |
3eb59ec6 | 3635 | goto err_free_percpu_ref; |
c81c925a TH |
3636 | |
3637 | err = online_css(css); | |
3638 | if (err) | |
3eb59ec6 | 3639 | goto err_clear_dir; |
c81c925a | 3640 | |
59f5296b | 3641 | cgroup_get(cgrp); |
c81c925a TH |
3642 | css_get(css->parent); |
3643 | ||
94419627 TH |
3644 | cgrp->subsys_mask |= 1 << ss->id; |
3645 | ||
c81c925a TH |
3646 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
3647 | parent->parent) { | |
3648 | 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", | |
3649 | current->comm, current->pid, ss->name); | |
3650 | if (!strcmp(ss->name, "memory")) | |
3651 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
3652 | ss->warned_broken_hierarchy = true; | |
3653 | } | |
3654 | ||
3655 | return 0; | |
3656 | ||
3eb59ec6 | 3657 | err_clear_dir: |
32d01dc7 | 3658 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3eb59ec6 | 3659 | err_free_percpu_ref: |
c81c925a | 3660 | percpu_ref_cancel_init(&css->refcnt); |
3eb59ec6 | 3661 | err_free_css: |
c81c925a TH |
3662 | ss->css_free(css); |
3663 | return err; | |
3664 | } | |
3665 | ||
2bd59d48 | 3666 | /** |
a043e3b2 LZ |
3667 | * cgroup_create - create a cgroup |
3668 | * @parent: cgroup that will be parent of the new cgroup | |
e61734c5 | 3669 | * @name: name of the new cgroup |
2bd59d48 | 3670 | * @mode: mode to set on new cgroup |
ddbcc7e8 | 3671 | */ |
e61734c5 | 3672 | static long cgroup_create(struct cgroup *parent, const char *name, |
2bd59d48 | 3673 | umode_t mode) |
ddbcc7e8 | 3674 | { |
bd89aabc | 3675 | struct cgroup *cgrp; |
3dd06ffa | 3676 | struct cgroup_root *root = parent->root; |
b58c8998 | 3677 | int ssid, err; |
ddbcc7e8 | 3678 | struct cgroup_subsys *ss; |
2bd59d48 | 3679 | struct kernfs_node *kn; |
ddbcc7e8 | 3680 | |
a2dd4247 TH |
3681 | /* |
3682 | * XXX: The default hierarchy isn't fully implemented yet. Block | |
3683 | * !root cgroup creation on it for now. | |
3684 | */ | |
3685 | if (root == &cgrp_dfl_root) | |
3686 | return -EINVAL; | |
ddbcc7e8 | 3687 | |
0a950f65 | 3688 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc PM |
3689 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3690 | if (!cgrp) | |
ddbcc7e8 PM |
3691 | return -ENOMEM; |
3692 | ||
ace2bee8 | 3693 | mutex_lock(&cgroup_tree_mutex); |
65dff759 | 3694 | |
976c06bc TH |
3695 | /* |
3696 | * Only live parents can have children. Note that the liveliness | |
3697 | * check isn't strictly necessary because cgroup_mkdir() and | |
3698 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
3699 | * anyway so that locking is contained inside cgroup proper and we | |
3700 | * don't get nasty surprises if we ever grow another caller. | |
3701 | */ | |
3702 | if (!cgroup_lock_live_group(parent)) { | |
3703 | err = -ENODEV; | |
ace2bee8 | 3704 | goto err_unlock_tree; |
0ab02ca8 LZ |
3705 | } |
3706 | ||
3707 | /* | |
3708 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
3709 | * a half-baked cgroup. | |
3710 | */ | |
3711 | cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL); | |
3712 | if (cgrp->id < 0) { | |
3713 | err = -ENOMEM; | |
3714 | goto err_unlock; | |
976c06bc TH |
3715 | } |
3716 | ||
cc31edce | 3717 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 3718 | |
bd89aabc | 3719 | cgrp->parent = parent; |
0ae78e0b | 3720 | cgrp->dummy_css.parent = &parent->dummy_css; |
bd89aabc | 3721 | cgrp->root = parent->root; |
ddbcc7e8 | 3722 | |
b6abdb0e LZ |
3723 | if (notify_on_release(parent)) |
3724 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3725 | ||
2260e7fc TH |
3726 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
3727 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 3728 | |
2bd59d48 | 3729 | /* create the directory */ |
e61734c5 | 3730 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 TH |
3731 | if (IS_ERR(kn)) { |
3732 | err = PTR_ERR(kn); | |
0ab02ca8 | 3733 | goto err_free_id; |
2bd59d48 TH |
3734 | } |
3735 | cgrp->kn = kn; | |
ddbcc7e8 | 3736 | |
4e139afc | 3737 | /* |
6f30558f TH |
3738 | * This extra ref will be put in cgroup_free_fn() and guarantees |
3739 | * that @cgrp->kn is always accessible. | |
4e139afc | 3740 | */ |
6f30558f | 3741 | kernfs_get(kn); |
ddbcc7e8 | 3742 | |
00356bd5 | 3743 | cgrp->serial_nr = cgroup_serial_nr_next++; |
53fa5261 | 3744 | |
4e139afc | 3745 | /* allocation complete, commit to creation */ |
4e139afc | 3746 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); |
3c9c825b | 3747 | atomic_inc(&root->nr_cgrps); |
59f5296b | 3748 | cgroup_get(parent); |
415cf07a | 3749 | |
0d80255e TH |
3750 | /* |
3751 | * @cgrp is now fully operational. If something fails after this | |
3752 | * point, it'll be released via the normal destruction path. | |
3753 | */ | |
4e96ee8e LZ |
3754 | idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
3755 | ||
2bb566cb | 3756 | err = cgroup_addrm_files(cgrp, cgroup_base_files, true); |
628f7cd4 TH |
3757 | if (err) |
3758 | goto err_destroy; | |
3759 | ||
9d403e99 | 3760 | /* let's create and online css's */ |
b85d2040 | 3761 | for_each_subsys(ss, ssid) { |
3dd06ffa | 3762 | if (root->cgrp.subsys_mask & (1 << ssid)) { |
b85d2040 TH |
3763 | err = create_css(cgrp, ss); |
3764 | if (err) | |
3765 | goto err_destroy; | |
3766 | } | |
a8638030 | 3767 | } |
ddbcc7e8 | 3768 | |
2bd59d48 TH |
3769 | kernfs_activate(kn); |
3770 | ||
ddbcc7e8 | 3771 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 3772 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
3773 | |
3774 | return 0; | |
3775 | ||
0a950f65 | 3776 | err_free_id: |
4e96ee8e | 3777 | idr_remove(&root->cgroup_idr, cgrp->id); |
0ab02ca8 LZ |
3778 | err_unlock: |
3779 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 TH |
3780 | err_unlock_tree: |
3781 | mutex_unlock(&cgroup_tree_mutex); | |
bd89aabc | 3782 | kfree(cgrp); |
ddbcc7e8 | 3783 | return err; |
4b8b47eb TH |
3784 | |
3785 | err_destroy: | |
3786 | cgroup_destroy_locked(cgrp); | |
3787 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 3788 | mutex_unlock(&cgroup_tree_mutex); |
4b8b47eb | 3789 | return err; |
ddbcc7e8 PM |
3790 | } |
3791 | ||
2bd59d48 TH |
3792 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
3793 | umode_t mode) | |
ddbcc7e8 | 3794 | { |
2bd59d48 | 3795 | struct cgroup *parent = parent_kn->priv; |
e1b2dc17 | 3796 | int ret; |
ddbcc7e8 | 3797 | |
e1b2dc17 TH |
3798 | /* |
3799 | * cgroup_create() grabs cgroup_tree_mutex which nests outside | |
3800 | * kernfs active_ref and cgroup_create() already synchronizes | |
3801 | * properly against removal through cgroup_lock_live_group(). | |
3802 | * Break it before calling cgroup_create(). | |
3803 | */ | |
3804 | cgroup_get(parent); | |
3805 | kernfs_break_active_protection(parent_kn); | |
ddbcc7e8 | 3806 | |
e1b2dc17 TH |
3807 | ret = cgroup_create(parent, name, mode); |
3808 | ||
3809 | kernfs_unbreak_active_protection(parent_kn); | |
3810 | cgroup_put(parent); | |
3811 | return ret; | |
ddbcc7e8 PM |
3812 | } |
3813 | ||
223dbc38 TH |
3814 | /* |
3815 | * This is called when the refcnt of a css is confirmed to be killed. | |
3816 | * css_tryget() is now guaranteed to fail. | |
3817 | */ | |
3818 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 3819 | { |
223dbc38 TH |
3820 | struct cgroup_subsys_state *css = |
3821 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
3822 | struct cgroup *cgrp = css->cgroup; | |
d3daf28d | 3823 | |
ace2bee8 | 3824 | mutex_lock(&cgroup_tree_mutex); |
f20104de TH |
3825 | mutex_lock(&cgroup_mutex); |
3826 | ||
09a503ea TH |
3827 | /* |
3828 | * css_tryget() is guaranteed to fail now. Tell subsystems to | |
3829 | * initate destruction. | |
3830 | */ | |
3831 | offline_css(css); | |
3832 | ||
f20104de TH |
3833 | /* |
3834 | * If @cgrp is marked dead, it's waiting for refs of all css's to | |
3835 | * be disabled before proceeding to the second phase of cgroup | |
3836 | * destruction. If we are the last one, kick it off. | |
3837 | */ | |
09a503ea | 3838 | if (!cgrp->nr_css && cgroup_is_dead(cgrp)) |
f20104de TH |
3839 | cgroup_destroy_css_killed(cgrp); |
3840 | ||
3841 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 3842 | mutex_unlock(&cgroup_tree_mutex); |
09a503ea TH |
3843 | |
3844 | /* | |
3845 | * Put the css refs from kill_css(). Each css holds an extra | |
3846 | * reference to the cgroup's dentry and cgroup removal proceeds | |
3847 | * regardless of css refs. On the last put of each css, whenever | |
3848 | * that may be, the extra dentry ref is put so that dentry | |
3849 | * destruction happens only after all css's are released. | |
3850 | */ | |
3851 | css_put(css); | |
d3daf28d TH |
3852 | } |
3853 | ||
223dbc38 TH |
3854 | /* css kill confirmation processing requires process context, bounce */ |
3855 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
3856 | { |
3857 | struct cgroup_subsys_state *css = | |
3858 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
3859 | ||
223dbc38 | 3860 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 3861 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
3862 | } |
3863 | ||
94419627 | 3864 | static void __kill_css(struct cgroup_subsys_state *css) |
edae0c33 | 3865 | { |
94419627 TH |
3866 | lockdep_assert_held(&cgroup_tree_mutex); |
3867 | ||
2bd59d48 TH |
3868 | /* |
3869 | * This must happen before css is disassociated with its cgroup. | |
3870 | * See seq_css() for details. | |
3871 | */ | |
aec25020 | 3872 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3c14f8b4 | 3873 | |
edae0c33 TH |
3874 | /* |
3875 | * Killing would put the base ref, but we need to keep it alive | |
3876 | * until after ->css_offline(). | |
3877 | */ | |
3878 | css_get(css); | |
3879 | ||
3880 | /* | |
3881 | * cgroup core guarantees that, by the time ->css_offline() is | |
3882 | * invoked, no new css reference will be given out via | |
3883 | * css_tryget(). We can't simply call percpu_ref_kill() and | |
3884 | * proceed to offlining css's because percpu_ref_kill() doesn't | |
3885 | * guarantee that the ref is seen as killed on all CPUs on return. | |
3886 | * | |
3887 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
3888 | * css is confirmed to be seen as killed on all CPUs. | |
3889 | */ | |
3890 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
3891 | } |
3892 | ||
94419627 TH |
3893 | /** |
3894 | * kill_css - destroy a css | |
3895 | * @css: css to destroy | |
3896 | * | |
3897 | * This function initiates destruction of @css by removing cgroup interface | |
3898 | * files and putting its base reference. ->css_offline() will be invoked | |
3899 | * asynchronously once css_tryget() is guaranteed to fail and when the | |
3900 | * reference count reaches zero, @css will be released. | |
3901 | */ | |
3902 | static void kill_css(struct cgroup_subsys_state *css) | |
3903 | { | |
3904 | struct cgroup *cgrp = css->cgroup; | |
3905 | ||
3906 | lockdep_assert_held(&cgroup_tree_mutex); | |
3907 | ||
3908 | /* if already killed, noop */ | |
3909 | if (cgrp->subsys_mask & (1 << css->ss->id)) { | |
3910 | cgrp->subsys_mask &= ~(1 << css->ss->id); | |
3911 | __kill_css(css); | |
3912 | } | |
3913 | } | |
3914 | ||
d3daf28d TH |
3915 | /** |
3916 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
3917 | * @cgrp: cgroup to be destroyed | |
3918 | * | |
3919 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
3920 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
3921 | * guarantee that css_tryget() won't succeed by the time ->css_offline() is | |
3922 | * invoked. To satisfy all the requirements, destruction is implemented in | |
3923 | * the following two steps. | |
3924 | * | |
3925 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
3926 | * userland visible parts and start killing the percpu refcnts of | |
3927 | * css's. Set up so that the next stage will be kicked off once all | |
3928 | * the percpu refcnts are confirmed to be killed. | |
3929 | * | |
3930 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
3931 | * rest of destruction. Once all cgroup references are gone, the | |
3932 | * cgroup is RCU-freed. | |
3933 | * | |
3934 | * This function implements s1. After this step, @cgrp is gone as far as | |
3935 | * the userland is concerned and a new cgroup with the same name may be | |
3936 | * created. As cgroup doesn't care about the names internally, this | |
3937 | * doesn't cause any problem. | |
3938 | */ | |
42809dd4 TH |
3939 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
3940 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 3941 | { |
bb78a92f | 3942 | struct cgroup *child; |
2bd59d48 | 3943 | struct cgroup_subsys_state *css; |
ddd69148 | 3944 | bool empty; |
1c6727af | 3945 | int ssid; |
ddbcc7e8 | 3946 | |
ace2bee8 | 3947 | lockdep_assert_held(&cgroup_tree_mutex); |
42809dd4 TH |
3948 | lockdep_assert_held(&cgroup_mutex); |
3949 | ||
ddd69148 | 3950 | /* |
96d365e0 | 3951 | * css_set_rwsem synchronizes access to ->cset_links and prevents |
89c5509b | 3952 | * @cgrp from being removed while put_css_set() is in progress. |
ddd69148 | 3953 | */ |
96d365e0 | 3954 | down_read(&css_set_rwsem); |
bb78a92f | 3955 | empty = list_empty(&cgrp->cset_links); |
96d365e0 | 3956 | up_read(&css_set_rwsem); |
ddd69148 | 3957 | if (!empty) |
ddbcc7e8 | 3958 | return -EBUSY; |
a043e3b2 | 3959 | |
bb78a92f HD |
3960 | /* |
3961 | * Make sure there's no live children. We can't test ->children | |
3962 | * emptiness as dead children linger on it while being destroyed; | |
3963 | * otherwise, "rmdir parent/child parent" may fail with -EBUSY. | |
3964 | */ | |
3965 | empty = true; | |
3966 | rcu_read_lock(); | |
3967 | list_for_each_entry_rcu(child, &cgrp->children, sibling) { | |
3968 | empty = cgroup_is_dead(child); | |
3969 | if (!empty) | |
3970 | break; | |
3971 | } | |
3972 | rcu_read_unlock(); | |
3973 | if (!empty) | |
3974 | return -EBUSY; | |
3975 | ||
455050d2 TH |
3976 | /* |
3977 | * Mark @cgrp dead. This prevents further task migration and child | |
3978 | * creation by disabling cgroup_lock_live_group(). Note that | |
492eb21b | 3979 | * CGRP_DEAD assertion is depended upon by css_next_child() to |
455050d2 | 3980 | * resume iteration after dropping RCU read lock. See |
492eb21b | 3981 | * css_next_child() for details. |
455050d2 | 3982 | */ |
54766d4a | 3983 | set_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 | 3984 | |
88703267 | 3985 | /* |
edae0c33 TH |
3986 | * Initiate massacre of all css's. cgroup_destroy_css_killed() |
3987 | * will be invoked to perform the rest of destruction once the | |
4ac06017 TH |
3988 | * percpu refs of all css's are confirmed to be killed. This |
3989 | * involves removing the subsystem's files, drop cgroup_mutex. | |
88703267 | 3990 | */ |
4ac06017 | 3991 | mutex_unlock(&cgroup_mutex); |
1c6727af TH |
3992 | for_each_css(css, ssid, cgrp) |
3993 | kill_css(css); | |
4ac06017 | 3994 | mutex_lock(&cgroup_mutex); |
455050d2 | 3995 | |
455050d2 TH |
3996 | /* CGRP_DEAD is set, remove from ->release_list for the last time */ |
3997 | raw_spin_lock(&release_list_lock); | |
3998 | if (!list_empty(&cgrp->release_list)) | |
3999 | list_del_init(&cgrp->release_list); | |
4000 | raw_spin_unlock(&release_list_lock); | |
4001 | ||
4002 | /* | |
f20104de TH |
4003 | * If @cgrp has css's attached, the second stage of cgroup |
4004 | * destruction is kicked off from css_killed_work_fn() after the | |
4005 | * refs of all attached css's are killed. If @cgrp doesn't have | |
4006 | * any css, we kick it off here. | |
4007 | */ | |
4008 | if (!cgrp->nr_css) | |
4009 | cgroup_destroy_css_killed(cgrp); | |
4010 | ||
2bd59d48 TH |
4011 | /* remove @cgrp directory along with the base files */ |
4012 | mutex_unlock(&cgroup_mutex); | |
4013 | ||
455050d2 | 4014 | /* |
2bd59d48 TH |
4015 | * There are two control paths which try to determine cgroup from |
4016 | * dentry without going through kernfs - cgroupstats_build() and | |
4017 | * css_tryget_from_dir(). Those are supported by RCU protecting | |
4018 | * clearing of cgrp->kn->priv backpointer, which should happen | |
4019 | * after all files under it have been removed. | |
455050d2 | 4020 | */ |
6f30558f | 4021 | kernfs_remove(cgrp->kn); /* @cgrp has an extra ref on its kn */ |
2bd59d48 | 4022 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); |
2bd59d48 | 4023 | |
4ac06017 | 4024 | mutex_lock(&cgroup_mutex); |
455050d2 | 4025 | |
ea15f8cc TH |
4026 | return 0; |
4027 | }; | |
4028 | ||
d3daf28d | 4029 | /** |
f20104de | 4030 | * cgroup_destroy_css_killed - the second step of cgroup destruction |
d3daf28d TH |
4031 | * @work: cgroup->destroy_free_work |
4032 | * | |
4033 | * This function is invoked from a work item for a cgroup which is being | |
09a503ea TH |
4034 | * destroyed after all css's are offlined and performs the rest of |
4035 | * destruction. This is the second step of destruction described in the | |
4036 | * comment above cgroup_destroy_locked(). | |
d3daf28d | 4037 | */ |
f20104de | 4038 | static void cgroup_destroy_css_killed(struct cgroup *cgrp) |
ea15f8cc | 4039 | { |
ea15f8cc | 4040 | struct cgroup *parent = cgrp->parent; |
ea15f8cc | 4041 | |
ace2bee8 | 4042 | lockdep_assert_held(&cgroup_tree_mutex); |
f20104de | 4043 | lockdep_assert_held(&cgroup_mutex); |
ea15f8cc | 4044 | |
999cd8a4 | 4045 | /* delete this cgroup from parent->children */ |
eb6fd504 | 4046 | list_del_rcu(&cgrp->sibling); |
ed957793 | 4047 | |
59f5296b | 4048 | cgroup_put(cgrp); |
ddbcc7e8 | 4049 | |
bd89aabc | 4050 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd | 4051 | check_for_release(parent); |
ddbcc7e8 PM |
4052 | } |
4053 | ||
2bd59d48 | 4054 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 4055 | { |
2bd59d48 TH |
4056 | struct cgroup *cgrp = kn->priv; |
4057 | int ret = 0; | |
42809dd4 | 4058 | |
2bd59d48 TH |
4059 | /* |
4060 | * This is self-destruction but @kn can't be removed while this | |
4061 | * callback is in progress. Let's break active protection. Once | |
4062 | * the protection is broken, @cgrp can be destroyed at any point. | |
4063 | * Pin it so that it stays accessible. | |
4064 | */ | |
4065 | cgroup_get(cgrp); | |
4066 | kernfs_break_active_protection(kn); | |
42809dd4 | 4067 | |
ace2bee8 | 4068 | mutex_lock(&cgroup_tree_mutex); |
42809dd4 | 4069 | mutex_lock(&cgroup_mutex); |
8e3f6541 TH |
4070 | |
4071 | /* | |
2bd59d48 TH |
4072 | * @cgrp might already have been destroyed while we're trying to |
4073 | * grab the mutexes. | |
8e3f6541 | 4074 | */ |
2bd59d48 TH |
4075 | if (!cgroup_is_dead(cgrp)) |
4076 | ret = cgroup_destroy_locked(cgrp); | |
2bb566cb | 4077 | |
42809dd4 | 4078 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 4079 | mutex_unlock(&cgroup_tree_mutex); |
2bb566cb | 4080 | |
2bd59d48 TH |
4081 | kernfs_unbreak_active_protection(kn); |
4082 | cgroup_put(cgrp); | |
42809dd4 | 4083 | return ret; |
8e3f6541 TH |
4084 | } |
4085 | ||
2bd59d48 TH |
4086 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
4087 | .remount_fs = cgroup_remount, | |
4088 | .show_options = cgroup_show_options, | |
4089 | .mkdir = cgroup_mkdir, | |
4090 | .rmdir = cgroup_rmdir, | |
4091 | .rename = cgroup_rename, | |
4092 | }; | |
4093 | ||
06a11920 | 4094 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4095 | { |
ddbcc7e8 | 4096 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4097 | |
4098 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 4099 | |
ace2bee8 | 4100 | mutex_lock(&cgroup_tree_mutex); |
648bb56d TH |
4101 | mutex_lock(&cgroup_mutex); |
4102 | ||
0adb0704 | 4103 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 4104 | |
3dd06ffa TH |
4105 | /* Create the root cgroup state for this subsystem */ |
4106 | ss->root = &cgrp_dfl_root; | |
4107 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
4108 | /* We don't handle early failures gracefully */ |
4109 | BUG_ON(IS_ERR(css)); | |
3dd06ffa | 4110 | init_css(css, ss, &cgrp_dfl_root.cgrp); |
ddbcc7e8 | 4111 | |
e8d55fde | 4112 | /* Update the init_css_set to contain a subsys |
817929ec | 4113 | * pointer to this state - since the subsystem is |
e8d55fde | 4114 | * newly registered, all tasks and hence the |
3dd06ffa | 4115 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 4116 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 PM |
4117 | |
4118 | need_forkexit_callback |= ss->fork || ss->exit; | |
4119 | ||
e8d55fde LZ |
4120 | /* At system boot, before all subsystems have been |
4121 | * registered, no tasks have been forked, so we don't | |
4122 | * need to invoke fork callbacks here. */ | |
4123 | BUG_ON(!list_empty(&init_task.tasks)); | |
4124 | ||
ae7f164a | 4125 | BUG_ON(online_css(css)); |
a8638030 | 4126 | |
3dd06ffa | 4127 | cgrp_dfl_root.cgrp.subsys_mask |= 1 << ss->id; |
cf5d5941 BB |
4128 | |
4129 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 4130 | mutex_unlock(&cgroup_tree_mutex); |
cf5d5941 | 4131 | } |
cf5d5941 | 4132 | |
ddbcc7e8 | 4133 | /** |
a043e3b2 LZ |
4134 | * cgroup_init_early - cgroup initialization at system boot |
4135 | * | |
4136 | * Initialize cgroups at system boot, and initialize any | |
4137 | * subsystems that request early init. | |
ddbcc7e8 PM |
4138 | */ |
4139 | int __init cgroup_init_early(void) | |
4140 | { | |
a2dd4247 TH |
4141 | static struct cgroup_sb_opts __initdata opts = |
4142 | { .flags = CGRP_ROOT_SANE_BEHAVIOR }; | |
30159ec7 | 4143 | struct cgroup_subsys *ss; |
ddbcc7e8 | 4144 | int i; |
30159ec7 | 4145 | |
3dd06ffa | 4146 | init_cgroup_root(&cgrp_dfl_root, &opts); |
a4ea1cc9 | 4147 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 4148 | |
3ed80a62 | 4149 | for_each_subsys(ss, i) { |
aec25020 | 4150 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
4151 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
4152 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 4153 | ss->id, ss->name); |
073219e9 TH |
4154 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
4155 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
4156 | ||
aec25020 | 4157 | ss->id = i; |
073219e9 | 4158 | ss->name = cgroup_subsys_name[i]; |
ddbcc7e8 PM |
4159 | |
4160 | if (ss->early_init) | |
4161 | cgroup_init_subsys(ss); | |
4162 | } | |
4163 | return 0; | |
4164 | } | |
4165 | ||
4166 | /** | |
a043e3b2 LZ |
4167 | * cgroup_init - cgroup initialization |
4168 | * | |
4169 | * Register cgroup filesystem and /proc file, and initialize | |
4170 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4171 | */ |
4172 | int __init cgroup_init(void) | |
4173 | { | |
30159ec7 | 4174 | struct cgroup_subsys *ss; |
0ac801fe | 4175 | unsigned long key; |
172a2c06 | 4176 | int ssid, err; |
ddbcc7e8 | 4177 | |
2bd59d48 | 4178 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files)); |
ddbcc7e8 | 4179 | |
985ed670 | 4180 | mutex_lock(&cgroup_tree_mutex); |
54e7b4eb | 4181 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 4182 | |
82fe9b0d TH |
4183 | /* Add init_css_set to the hash table */ |
4184 | key = css_set_hash(init_css_set.subsys); | |
4185 | hash_add(css_set_table, &init_css_set.hlist, key); | |
4186 | ||
3dd06ffa | 4187 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 4188 | |
54e7b4eb | 4189 | mutex_unlock(&cgroup_mutex); |
985ed670 | 4190 | mutex_unlock(&cgroup_tree_mutex); |
54e7b4eb | 4191 | |
172a2c06 TH |
4192 | for_each_subsys(ss, ssid) { |
4193 | if (!ss->early_init) | |
4194 | cgroup_init_subsys(ss); | |
4195 | ||
4196 | /* | |
4197 | * cftype registration needs kmalloc and can't be done | |
4198 | * during early_init. Register base cftypes separately. | |
4199 | */ | |
4200 | if (ss->base_cftypes) | |
4201 | WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes)); | |
676db4af GKH |
4202 | } |
4203 | ||
676db4af | 4204 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
2bd59d48 TH |
4205 | if (!cgroup_kobj) |
4206 | return -ENOMEM; | |
676db4af | 4207 | |
ddbcc7e8 | 4208 | err = register_filesystem(&cgroup_fs_type); |
676db4af GKH |
4209 | if (err < 0) { |
4210 | kobject_put(cgroup_kobj); | |
2bd59d48 | 4211 | return err; |
676db4af | 4212 | } |
ddbcc7e8 | 4213 | |
46ae220b | 4214 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 4215 | return 0; |
ddbcc7e8 | 4216 | } |
b4f48b63 | 4217 | |
e5fca243 TH |
4218 | static int __init cgroup_wq_init(void) |
4219 | { | |
4220 | /* | |
4221 | * There isn't much point in executing destruction path in | |
4222 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 4223 | * Use 1 for @max_active. |
e5fca243 TH |
4224 | * |
4225 | * We would prefer to do this in cgroup_init() above, but that | |
4226 | * is called before init_workqueues(): so leave this until after. | |
4227 | */ | |
1a11533f | 4228 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 4229 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
4230 | |
4231 | /* | |
4232 | * Used to destroy pidlists and separate to serve as flush domain. | |
4233 | * Cap @max_active to 1 too. | |
4234 | */ | |
4235 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
4236 | 0, 1); | |
4237 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
4238 | ||
e5fca243 TH |
4239 | return 0; |
4240 | } | |
4241 | core_initcall(cgroup_wq_init); | |
4242 | ||
a424316c PM |
4243 | /* |
4244 | * proc_cgroup_show() | |
4245 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4246 | * - Used for /proc/<pid>/cgroup. | |
a424316c PM |
4247 | */ |
4248 | ||
4249 | /* TODO: Use a proper seq_file iterator */ | |
8d8b97ba | 4250 | int proc_cgroup_show(struct seq_file *m, void *v) |
a424316c PM |
4251 | { |
4252 | struct pid *pid; | |
4253 | struct task_struct *tsk; | |
e61734c5 | 4254 | char *buf, *path; |
a424316c | 4255 | int retval; |
3dd06ffa | 4256 | struct cgroup_root *root; |
a424316c PM |
4257 | |
4258 | retval = -ENOMEM; | |
e61734c5 | 4259 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
4260 | if (!buf) |
4261 | goto out; | |
4262 | ||
4263 | retval = -ESRCH; | |
4264 | pid = m->private; | |
4265 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4266 | if (!tsk) | |
4267 | goto out_free; | |
4268 | ||
4269 | retval = 0; | |
4270 | ||
4271 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 4272 | down_read(&css_set_rwsem); |
a424316c | 4273 | |
985ed670 | 4274 | for_each_root(root) { |
a424316c | 4275 | struct cgroup_subsys *ss; |
bd89aabc | 4276 | struct cgroup *cgrp; |
b85d2040 | 4277 | int ssid, count = 0; |
a424316c | 4278 | |
a2dd4247 | 4279 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible) |
985ed670 TH |
4280 | continue; |
4281 | ||
2c6ab6d2 | 4282 | seq_printf(m, "%d:", root->hierarchy_id); |
b85d2040 | 4283 | for_each_subsys(ss, ssid) |
3dd06ffa | 4284 | if (root->cgrp.subsys_mask & (1 << ssid)) |
b85d2040 | 4285 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); |
c6d57f33 PM |
4286 | if (strlen(root->name)) |
4287 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4288 | root->name); | |
a424316c | 4289 | seq_putc(m, ':'); |
7717f7ba | 4290 | cgrp = task_cgroup_from_root(tsk, root); |
e61734c5 TH |
4291 | path = cgroup_path(cgrp, buf, PATH_MAX); |
4292 | if (!path) { | |
4293 | retval = -ENAMETOOLONG; | |
a424316c | 4294 | goto out_unlock; |
e61734c5 TH |
4295 | } |
4296 | seq_puts(m, path); | |
a424316c PM |
4297 | seq_putc(m, '\n'); |
4298 | } | |
4299 | ||
4300 | out_unlock: | |
96d365e0 | 4301 | up_read(&css_set_rwsem); |
a424316c PM |
4302 | mutex_unlock(&cgroup_mutex); |
4303 | put_task_struct(tsk); | |
4304 | out_free: | |
4305 | kfree(buf); | |
4306 | out: | |
4307 | return retval; | |
4308 | } | |
4309 | ||
a424316c PM |
4310 | /* Display information about each subsystem and each hierarchy */ |
4311 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4312 | { | |
30159ec7 | 4313 | struct cgroup_subsys *ss; |
a424316c | 4314 | int i; |
a424316c | 4315 | |
8bab8dde | 4316 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4317 | /* |
4318 | * ideally we don't want subsystems moving around while we do this. | |
4319 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4320 | * subsys/hierarchy state. | |
4321 | */ | |
a424316c | 4322 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
4323 | |
4324 | for_each_subsys(ss, i) | |
2c6ab6d2 PM |
4325 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4326 | ss->name, ss->root->hierarchy_id, | |
3c9c825b | 4327 | atomic_read(&ss->root->nr_cgrps), !ss->disabled); |
30159ec7 | 4328 | |
a424316c PM |
4329 | mutex_unlock(&cgroup_mutex); |
4330 | return 0; | |
4331 | } | |
4332 | ||
4333 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4334 | { | |
9dce07f1 | 4335 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4336 | } |
4337 | ||
828c0950 | 4338 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4339 | .open = cgroupstats_open, |
4340 | .read = seq_read, | |
4341 | .llseek = seq_lseek, | |
4342 | .release = single_release, | |
4343 | }; | |
4344 | ||
b4f48b63 | 4345 | /** |
eaf797ab | 4346 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 4347 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 4348 | * |
eaf797ab TH |
4349 | * A task is associated with the init_css_set until cgroup_post_fork() |
4350 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
4351 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
4352 | */ |
4353 | void cgroup_fork(struct task_struct *child) | |
4354 | { | |
eaf797ab | 4355 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 4356 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
4357 | } |
4358 | ||
817929ec | 4359 | /** |
a043e3b2 LZ |
4360 | * cgroup_post_fork - called on a new task after adding it to the task list |
4361 | * @child: the task in question | |
4362 | * | |
5edee61e TH |
4363 | * Adds the task to the list running through its css_set if necessary and |
4364 | * call the subsystem fork() callbacks. Has to be after the task is | |
4365 | * visible on the task list in case we race with the first call to | |
0942eeee | 4366 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 4367 | * list. |
a043e3b2 | 4368 | */ |
817929ec PM |
4369 | void cgroup_post_fork(struct task_struct *child) |
4370 | { | |
30159ec7 | 4371 | struct cgroup_subsys *ss; |
5edee61e TH |
4372 | int i; |
4373 | ||
3ce3230a | 4374 | /* |
eaf797ab TH |
4375 | * This may race against cgroup_enable_task_cg_links(). As that |
4376 | * function sets use_task_css_set_links before grabbing | |
4377 | * tasklist_lock and we just went through tasklist_lock to add | |
4378 | * @child, it's guaranteed that either we see the set | |
4379 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
4380 | * @child during its iteration. | |
4381 | * | |
4382 | * If we won the race, @child is associated with %current's | |
4383 | * css_set. Grabbing css_set_rwsem guarantees both that the | |
4384 | * association is stable, and, on completion of the parent's | |
4385 | * migration, @child is visible in the source of migration or | |
4386 | * already in the destination cgroup. This guarantee is necessary | |
4387 | * when implementing operations which need to migrate all tasks of | |
4388 | * a cgroup to another. | |
4389 | * | |
4390 | * Note that if we lose to cgroup_enable_task_cg_links(), @child | |
4391 | * will remain in init_css_set. This is safe because all tasks are | |
4392 | * in the init_css_set before cg_links is enabled and there's no | |
4393 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 4394 | */ |
817929ec | 4395 | if (use_task_css_set_links) { |
eaf797ab TH |
4396 | struct css_set *cset; |
4397 | ||
96d365e0 | 4398 | down_write(&css_set_rwsem); |
0e1d768f | 4399 | cset = task_css_set(current); |
eaf797ab TH |
4400 | if (list_empty(&child->cg_list)) { |
4401 | rcu_assign_pointer(child->cgroups, cset); | |
4402 | list_add(&child->cg_list, &cset->tasks); | |
4403 | get_css_set(cset); | |
4404 | } | |
96d365e0 | 4405 | up_write(&css_set_rwsem); |
817929ec | 4406 | } |
5edee61e TH |
4407 | |
4408 | /* | |
4409 | * Call ss->fork(). This must happen after @child is linked on | |
4410 | * css_set; otherwise, @child might change state between ->fork() | |
4411 | * and addition to css_set. | |
4412 | */ | |
4413 | if (need_forkexit_callback) { | |
3ed80a62 | 4414 | for_each_subsys(ss, i) |
5edee61e TH |
4415 | if (ss->fork) |
4416 | ss->fork(child); | |
5edee61e | 4417 | } |
817929ec | 4418 | } |
5edee61e | 4419 | |
b4f48b63 PM |
4420 | /** |
4421 | * cgroup_exit - detach cgroup from exiting task | |
4422 | * @tsk: pointer to task_struct of exiting process | |
4423 | * | |
4424 | * Description: Detach cgroup from @tsk and release it. | |
4425 | * | |
4426 | * Note that cgroups marked notify_on_release force every task in | |
4427 | * them to take the global cgroup_mutex mutex when exiting. | |
4428 | * This could impact scaling on very large systems. Be reluctant to | |
4429 | * use notify_on_release cgroups where very high task exit scaling | |
4430 | * is required on large systems. | |
4431 | * | |
0e1d768f TH |
4432 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
4433 | * call cgroup_exit() while the task is still competent to handle | |
4434 | * notify_on_release(), then leave the task attached to the root cgroup in | |
4435 | * each hierarchy for the remainder of its exit. No need to bother with | |
4436 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 4437 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 4438 | */ |
1ec41830 | 4439 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 4440 | { |
30159ec7 | 4441 | struct cgroup_subsys *ss; |
5abb8855 | 4442 | struct css_set *cset; |
eaf797ab | 4443 | bool put_cset = false; |
d41d5a01 | 4444 | int i; |
817929ec PM |
4445 | |
4446 | /* | |
0e1d768f TH |
4447 | * Unlink from @tsk from its css_set. As migration path can't race |
4448 | * with us, we can check cg_list without grabbing css_set_rwsem. | |
817929ec PM |
4449 | */ |
4450 | if (!list_empty(&tsk->cg_list)) { | |
96d365e0 | 4451 | down_write(&css_set_rwsem); |
0e1d768f | 4452 | list_del_init(&tsk->cg_list); |
96d365e0 | 4453 | up_write(&css_set_rwsem); |
0e1d768f | 4454 | put_cset = true; |
817929ec PM |
4455 | } |
4456 | ||
b4f48b63 | 4457 | /* Reassign the task to the init_css_set. */ |
a8ad805c TH |
4458 | cset = task_css_set(tsk); |
4459 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 | 4460 | |
1ec41830 | 4461 | if (need_forkexit_callback) { |
3ed80a62 TH |
4462 | /* see cgroup_post_fork() for details */ |
4463 | for_each_subsys(ss, i) { | |
d41d5a01 | 4464 | if (ss->exit) { |
eb95419b TH |
4465 | struct cgroup_subsys_state *old_css = cset->subsys[i]; |
4466 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 4467 | |
eb95419b | 4468 | ss->exit(css, old_css, tsk); |
d41d5a01 PZ |
4469 | } |
4470 | } | |
4471 | } | |
d41d5a01 | 4472 | |
eaf797ab TH |
4473 | if (put_cset) |
4474 | put_css_set(cset, true); | |
b4f48b63 | 4475 | } |
697f4161 | 4476 | |
bd89aabc | 4477 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 4478 | { |
f50daa70 | 4479 | if (cgroup_is_releasable(cgrp) && |
6f3d828f | 4480 | list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { |
f50daa70 LZ |
4481 | /* |
4482 | * Control Group is currently removeable. If it's not | |
81a6a5cd | 4483 | * already queued for a userspace notification, queue |
f50daa70 LZ |
4484 | * it now |
4485 | */ | |
81a6a5cd | 4486 | int need_schedule_work = 0; |
f50daa70 | 4487 | |
cdcc136f | 4488 | raw_spin_lock(&release_list_lock); |
54766d4a | 4489 | if (!cgroup_is_dead(cgrp) && |
bd89aabc PM |
4490 | list_empty(&cgrp->release_list)) { |
4491 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4492 | need_schedule_work = 1; |
4493 | } | |
cdcc136f | 4494 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4495 | if (need_schedule_work) |
4496 | schedule_work(&release_agent_work); | |
4497 | } | |
4498 | } | |
4499 | ||
81a6a5cd PM |
4500 | /* |
4501 | * Notify userspace when a cgroup is released, by running the | |
4502 | * configured release agent with the name of the cgroup (path | |
4503 | * relative to the root of cgroup file system) as the argument. | |
4504 | * | |
4505 | * Most likely, this user command will try to rmdir this cgroup. | |
4506 | * | |
4507 | * This races with the possibility that some other task will be | |
4508 | * attached to this cgroup before it is removed, or that some other | |
4509 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
4510 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
4511 | * unused, and this cgroup will be reprieved from its death sentence, | |
4512 | * to continue to serve a useful existence. Next time it's released, | |
4513 | * we will get notified again, if it still has 'notify_on_release' set. | |
4514 | * | |
4515 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
4516 | * means only wait until the task is successfully execve()'d. The | |
4517 | * separate release agent task is forked by call_usermodehelper(), | |
4518 | * then control in this thread returns here, without waiting for the | |
4519 | * release agent task. We don't bother to wait because the caller of | |
4520 | * this routine has no use for the exit status of the release agent | |
4521 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 4522 | */ |
81a6a5cd PM |
4523 | static void cgroup_release_agent(struct work_struct *work) |
4524 | { | |
4525 | BUG_ON(work != &release_agent_work); | |
4526 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 4527 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
4528 | while (!list_empty(&release_list)) { |
4529 | char *argv[3], *envp[3]; | |
4530 | int i; | |
e61734c5 | 4531 | char *pathbuf = NULL, *agentbuf = NULL, *path; |
bd89aabc | 4532 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
4533 | struct cgroup, |
4534 | release_list); | |
bd89aabc | 4535 | list_del_init(&cgrp->release_list); |
cdcc136f | 4536 | raw_spin_unlock(&release_list_lock); |
e61734c5 | 4537 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
e788e066 PM |
4538 | if (!pathbuf) |
4539 | goto continue_free; | |
e61734c5 TH |
4540 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); |
4541 | if (!path) | |
e788e066 PM |
4542 | goto continue_free; |
4543 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
4544 | if (!agentbuf) | |
4545 | goto continue_free; | |
81a6a5cd PM |
4546 | |
4547 | i = 0; | |
e788e066 | 4548 | argv[i++] = agentbuf; |
e61734c5 | 4549 | argv[i++] = path; |
81a6a5cd PM |
4550 | argv[i] = NULL; |
4551 | ||
4552 | i = 0; | |
4553 | /* minimal command environment */ | |
4554 | envp[i++] = "HOME=/"; | |
4555 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
4556 | envp[i] = NULL; | |
4557 | ||
4558 | /* Drop the lock while we invoke the usermode helper, | |
4559 | * since the exec could involve hitting disk and hence | |
4560 | * be a slow process */ | |
4561 | mutex_unlock(&cgroup_mutex); | |
4562 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 4563 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
4564 | continue_free: |
4565 | kfree(pathbuf); | |
4566 | kfree(agentbuf); | |
cdcc136f | 4567 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 4568 | } |
cdcc136f | 4569 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4570 | mutex_unlock(&cgroup_mutex); |
4571 | } | |
8bab8dde PM |
4572 | |
4573 | static int __init cgroup_disable(char *str) | |
4574 | { | |
30159ec7 | 4575 | struct cgroup_subsys *ss; |
8bab8dde | 4576 | char *token; |
30159ec7 | 4577 | int i; |
8bab8dde PM |
4578 | |
4579 | while ((token = strsep(&str, ",")) != NULL) { | |
4580 | if (!*token) | |
4581 | continue; | |
be45c900 | 4582 | |
3ed80a62 | 4583 | for_each_subsys(ss, i) { |
8bab8dde PM |
4584 | if (!strcmp(token, ss->name)) { |
4585 | ss->disabled = 1; | |
4586 | printk(KERN_INFO "Disabling %s control group" | |
4587 | " subsystem\n", ss->name); | |
4588 | break; | |
4589 | } | |
4590 | } | |
4591 | } | |
4592 | return 1; | |
4593 | } | |
4594 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 4595 | |
b77d7b60 | 4596 | /** |
5a17f543 | 4597 | * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir |
35cf0836 TH |
4598 | * @dentry: directory dentry of interest |
4599 | * @ss: subsystem of interest | |
b77d7b60 | 4600 | * |
5a17f543 TH |
4601 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
4602 | * to get the corresponding css and return it. If such css doesn't exist | |
4603 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 4604 | */ |
5a17f543 TH |
4605 | struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, |
4606 | struct cgroup_subsys *ss) | |
e5d1367f | 4607 | { |
2bd59d48 TH |
4608 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
4609 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 4610 | struct cgroup *cgrp; |
e5d1367f | 4611 | |
35cf0836 | 4612 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
4613 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
4614 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
4615 | return ERR_PTR(-EBADF); |
4616 | ||
5a17f543 TH |
4617 | rcu_read_lock(); |
4618 | ||
2bd59d48 TH |
4619 | /* |
4620 | * This path doesn't originate from kernfs and @kn could already | |
4621 | * have been or be removed at any point. @kn->priv is RCU | |
4622 | * protected for this access. See destroy_locked() for details. | |
4623 | */ | |
4624 | cgrp = rcu_dereference(kn->priv); | |
4625 | if (cgrp) | |
4626 | css = cgroup_css(cgrp, ss); | |
5a17f543 TH |
4627 | |
4628 | if (!css || !css_tryget(css)) | |
4629 | css = ERR_PTR(-ENOENT); | |
4630 | ||
4631 | rcu_read_unlock(); | |
4632 | return css; | |
e5d1367f | 4633 | } |
e5d1367f | 4634 | |
1cb650b9 LZ |
4635 | /** |
4636 | * css_from_id - lookup css by id | |
4637 | * @id: the cgroup id | |
4638 | * @ss: cgroup subsys to be looked into | |
4639 | * | |
4640 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
4641 | * Should be called under rcu_read_lock(). | |
4642 | */ | |
4643 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
4644 | { | |
4645 | struct cgroup *cgrp; | |
4646 | ||
ace2bee8 | 4647 | cgroup_assert_mutexes_or_rcu_locked(); |
1cb650b9 LZ |
4648 | |
4649 | cgrp = idr_find(&ss->root->cgroup_idr, id); | |
4650 | if (cgrp) | |
d1625964 | 4651 | return cgroup_css(cgrp, ss); |
1cb650b9 | 4652 | return NULL; |
e5d1367f SE |
4653 | } |
4654 | ||
fe693435 | 4655 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
4656 | static struct cgroup_subsys_state * |
4657 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
4658 | { |
4659 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
4660 | ||
4661 | if (!css) | |
4662 | return ERR_PTR(-ENOMEM); | |
4663 | ||
4664 | return css; | |
4665 | } | |
4666 | ||
eb95419b | 4667 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 4668 | { |
eb95419b | 4669 | kfree(css); |
fe693435 PM |
4670 | } |
4671 | ||
182446d0 TH |
4672 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
4673 | struct cftype *cft) | |
fe693435 | 4674 | { |
182446d0 | 4675 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
4676 | } |
4677 | ||
182446d0 TH |
4678 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
4679 | struct cftype *cft) | |
fe693435 PM |
4680 | { |
4681 | return (u64)(unsigned long)current->cgroups; | |
4682 | } | |
4683 | ||
182446d0 | 4684 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 4685 | struct cftype *cft) |
fe693435 PM |
4686 | { |
4687 | u64 count; | |
4688 | ||
4689 | rcu_read_lock(); | |
a8ad805c | 4690 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
4691 | rcu_read_unlock(); |
4692 | return count; | |
4693 | } | |
4694 | ||
2da8ca82 | 4695 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 4696 | { |
69d0206c | 4697 | struct cgrp_cset_link *link; |
5abb8855 | 4698 | struct css_set *cset; |
e61734c5 TH |
4699 | char *name_buf; |
4700 | ||
4701 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
4702 | if (!name_buf) | |
4703 | return -ENOMEM; | |
7717f7ba | 4704 | |
96d365e0 | 4705 | down_read(&css_set_rwsem); |
7717f7ba | 4706 | rcu_read_lock(); |
5abb8855 | 4707 | cset = rcu_dereference(current->cgroups); |
69d0206c | 4708 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 4709 | struct cgroup *c = link->cgrp; |
7717f7ba | 4710 | |
a2dd4247 | 4711 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 4712 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 4713 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
4714 | } |
4715 | rcu_read_unlock(); | |
96d365e0 | 4716 | up_read(&css_set_rwsem); |
e61734c5 | 4717 | kfree(name_buf); |
7717f7ba PM |
4718 | return 0; |
4719 | } | |
4720 | ||
4721 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 4722 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 4723 | { |
2da8ca82 | 4724 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 4725 | struct cgrp_cset_link *link; |
7717f7ba | 4726 | |
96d365e0 | 4727 | down_read(&css_set_rwsem); |
182446d0 | 4728 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 4729 | struct css_set *cset = link->cset; |
7717f7ba PM |
4730 | struct task_struct *task; |
4731 | int count = 0; | |
c7561128 | 4732 | |
5abb8855 | 4733 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 4734 | |
5abb8855 | 4735 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
4736 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
4737 | goto overflow; | |
4738 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
4739 | } | |
4740 | ||
4741 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
4742 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
4743 | goto overflow; | |
4744 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 4745 | } |
c7561128 TH |
4746 | continue; |
4747 | overflow: | |
4748 | seq_puts(seq, " ...\n"); | |
7717f7ba | 4749 | } |
96d365e0 | 4750 | up_read(&css_set_rwsem); |
7717f7ba PM |
4751 | return 0; |
4752 | } | |
4753 | ||
182446d0 | 4754 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 4755 | { |
182446d0 | 4756 | return test_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
fe693435 PM |
4757 | } |
4758 | ||
4759 | static struct cftype debug_files[] = { | |
fe693435 PM |
4760 | { |
4761 | .name = "taskcount", | |
4762 | .read_u64 = debug_taskcount_read, | |
4763 | }, | |
4764 | ||
4765 | { | |
4766 | .name = "current_css_set", | |
4767 | .read_u64 = current_css_set_read, | |
4768 | }, | |
4769 | ||
4770 | { | |
4771 | .name = "current_css_set_refcount", | |
4772 | .read_u64 = current_css_set_refcount_read, | |
4773 | }, | |
4774 | ||
7717f7ba PM |
4775 | { |
4776 | .name = "current_css_set_cg_links", | |
2da8ca82 | 4777 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
4778 | }, |
4779 | ||
4780 | { | |
4781 | .name = "cgroup_css_links", | |
2da8ca82 | 4782 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
4783 | }, |
4784 | ||
fe693435 PM |
4785 | { |
4786 | .name = "releasable", | |
4787 | .read_u64 = releasable_read, | |
4788 | }, | |
fe693435 | 4789 | |
4baf6e33 TH |
4790 | { } /* terminate */ |
4791 | }; | |
fe693435 | 4792 | |
073219e9 | 4793 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
4794 | .css_alloc = debug_css_alloc, |
4795 | .css_free = debug_css_free, | |
4baf6e33 | 4796 | .base_cftypes = debug_files, |
fe693435 PM |
4797 | }; |
4798 | #endif /* CONFIG_CGROUP_DEBUG */ |