Commit | Line | Data |
---|---|---|
ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
29 | #include <linux/cgroup.h> | |
2ce9738b | 30 | #include <linux/cred.h> |
c6d57f33 | 31 | #include <linux/ctype.h> |
ddbcc7e8 | 32 | #include <linux/errno.h> |
2ce9738b | 33 | #include <linux/init_task.h> |
ddbcc7e8 PM |
34 | #include <linux/kernel.h> |
35 | #include <linux/list.h> | |
36 | #include <linux/mm.h> | |
37 | #include <linux/mutex.h> | |
38 | #include <linux/mount.h> | |
39 | #include <linux/pagemap.h> | |
a424316c | 40 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
41 | #include <linux/rcupdate.h> |
42 | #include <linux/sched.h> | |
ddbcc7e8 | 43 | #include <linux/slab.h> |
ddbcc7e8 | 44 | #include <linux/spinlock.h> |
96d365e0 | 45 | #include <linux/rwsem.h> |
ddbcc7e8 | 46 | #include <linux/string.h> |
bbcb81d0 | 47 | #include <linux/sort.h> |
81a6a5cd | 48 | #include <linux/kmod.h> |
846c7bb0 BS |
49 | #include <linux/delayacct.h> |
50 | #include <linux/cgroupstats.h> | |
0ac801fe | 51 | #include <linux/hashtable.h> |
096b7fe0 | 52 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 53 | #include <linux/idr.h> |
d1d9fd33 | 54 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 55 | #include <linux/kthread.h> |
776f02fa | 56 | #include <linux/delay.h> |
846c7bb0 | 57 | |
60063497 | 58 | #include <linux/atomic.h> |
ddbcc7e8 | 59 | |
b1a21367 TH |
60 | /* |
61 | * pidlists linger the following amount before being destroyed. The goal | |
62 | * is avoiding frequent destruction in the middle of consecutive read calls | |
63 | * Expiring in the middle is a performance problem not a correctness one. | |
64 | * 1 sec should be enough. | |
65 | */ | |
66 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
67 | ||
8d7e6fb0 TH |
68 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
69 | MAX_CFTYPE_NAME + 2) | |
70 | ||
ace2bee8 TH |
71 | /* |
72 | * cgroup_tree_mutex nests above cgroup_mutex and protects cftypes, file | |
73 | * creation/removal and hierarchy changing operations including cgroup | |
74 | * creation, removal, css association and controller rebinding. This outer | |
75 | * lock is needed mainly to resolve the circular dependency between kernfs | |
76 | * active ref and cgroup_mutex. cgroup_tree_mutex nests above both. | |
77 | */ | |
78 | static DEFINE_MUTEX(cgroup_tree_mutex); | |
79 | ||
e25e2cbb TH |
80 | /* |
81 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
82 | * hierarchy must be performed while holding it. | |
e25e2cbb | 83 | */ |
2219449a TH |
84 | #ifdef CONFIG_PROVE_RCU |
85 | DEFINE_MUTEX(cgroup_mutex); | |
8af01f56 | 86 | EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for lockdep */ |
2219449a | 87 | #else |
81a6a5cd | 88 | static DEFINE_MUTEX(cgroup_mutex); |
2219449a TH |
89 | #endif |
90 | ||
69e943b7 TH |
91 | /* |
92 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
93 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
94 | */ | |
95 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
96 | ||
ace2bee8 | 97 | #define cgroup_assert_mutexes_or_rcu_locked() \ |
87fb54f1 | 98 | rcu_lockdep_assert(rcu_read_lock_held() || \ |
ace2bee8 | 99 | lockdep_is_held(&cgroup_tree_mutex) || \ |
87fb54f1 | 100 | lockdep_is_held(&cgroup_mutex), \ |
ace2bee8 | 101 | "cgroup_[tree_]mutex or RCU read lock required"); |
87fb54f1 | 102 | |
e5fca243 TH |
103 | /* |
104 | * cgroup destruction makes heavy use of work items and there can be a lot | |
105 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
106 | * destruction work items don't end up filling up max_active of system_wq | |
107 | * which may lead to deadlock. | |
108 | */ | |
109 | static struct workqueue_struct *cgroup_destroy_wq; | |
110 | ||
b1a21367 TH |
111 | /* |
112 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
113 | * separate workqueue as flush domain. | |
114 | */ | |
115 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
116 | ||
3ed80a62 | 117 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 118 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 119 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
120 | #include <linux/cgroup_subsys.h> |
121 | }; | |
073219e9 TH |
122 | #undef SUBSYS |
123 | ||
124 | /* array of cgroup subsystem names */ | |
125 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
126 | static const char *cgroup_subsys_name[] = { | |
127 | #include <linux/cgroup_subsys.h> | |
128 | }; | |
129 | #undef SUBSYS | |
ddbcc7e8 | 130 | |
ddbcc7e8 | 131 | /* |
9871bf95 TH |
132 | * The dummy hierarchy, reserved for the subsystems that are otherwise |
133 | * unattached - it never has more than a single cgroup, and all tasks are | |
134 | * part of that cgroup. | |
ddbcc7e8 | 135 | */ |
9871bf95 TH |
136 | static struct cgroupfs_root cgroup_dummy_root; |
137 | ||
138 | /* dummy_top is a shorthand for the dummy hierarchy's top cgroup */ | |
139 | static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup; | |
ddbcc7e8 PM |
140 | |
141 | /* The list of hierarchy roots */ | |
142 | ||
9871bf95 TH |
143 | static LIST_HEAD(cgroup_roots); |
144 | static int cgroup_root_count; | |
ddbcc7e8 | 145 | |
3417ae1f | 146 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 147 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 148 | |
794611a1 LZ |
149 | /* |
150 | * Assign a monotonically increasing serial number to cgroups. It | |
151 | * guarantees cgroups with bigger numbers are newer than those with smaller | |
152 | * numbers. Also, as cgroups are always appended to the parent's | |
153 | * ->children list, it guarantees that sibling cgroups are always sorted in | |
00356bd5 TH |
154 | * the ascending serial number order on the list. Protected by |
155 | * cgroup_mutex. | |
794611a1 | 156 | */ |
00356bd5 | 157 | static u64 cgroup_serial_nr_next = 1; |
794611a1 | 158 | |
ddbcc7e8 | 159 | /* This flag indicates whether tasks in the fork and exit paths should |
a043e3b2 LZ |
160 | * check for fork/exit handlers to call. This avoids us having to do |
161 | * extra work in the fork/exit path if none of the subsystems need to | |
162 | * be called. | |
ddbcc7e8 | 163 | */ |
8947f9d5 | 164 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 165 | |
628f7cd4 TH |
166 | static struct cftype cgroup_base_files[]; |
167 | ||
59f5296b | 168 | static void cgroup_put(struct cgroup *cgrp); |
f2e85d57 TH |
169 | static int rebind_subsystems(struct cgroupfs_root *root, |
170 | unsigned long added_mask, unsigned removed_mask); | |
f20104de | 171 | static void cgroup_destroy_css_killed(struct cgroup *cgrp); |
42809dd4 | 172 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
2bb566cb TH |
173 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
174 | bool is_add); | |
b1a21367 | 175 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp); |
42809dd4 | 176 | |
95109b62 TH |
177 | /** |
178 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
179 | * @cgrp: the cgroup of interest | |
ca8bdcaf | 180 | * @ss: the subsystem of interest (%NULL returns the dummy_css) |
95109b62 | 181 | * |
ca8bdcaf TH |
182 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
183 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
184 | * the caller is responsible for pinning the returned css if it wants to | |
185 | * keep accessing it outside the said locks. This function may return | |
186 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
187 | */ |
188 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 189 | struct cgroup_subsys *ss) |
95109b62 | 190 | { |
ca8bdcaf | 191 | if (ss) |
aec25020 | 192 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 TH |
193 | lockdep_is_held(&cgroup_tree_mutex) || |
194 | lockdep_is_held(&cgroup_mutex)); | |
ca8bdcaf TH |
195 | else |
196 | return &cgrp->dummy_css; | |
95109b62 | 197 | } |
42809dd4 | 198 | |
ddbcc7e8 | 199 | /* convenient tests for these bits */ |
54766d4a | 200 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 201 | { |
54766d4a | 202 | return test_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 PM |
203 | } |
204 | ||
59f5296b TH |
205 | struct cgroup_subsys_state *seq_css(struct seq_file *seq) |
206 | { | |
2bd59d48 TH |
207 | struct kernfs_open_file *of = seq->private; |
208 | struct cgroup *cgrp = of->kn->parent->priv; | |
209 | struct cftype *cft = seq_cft(seq); | |
210 | ||
211 | /* | |
212 | * This is open and unprotected implementation of cgroup_css(). | |
213 | * seq_css() is only called from a kernfs file operation which has | |
214 | * an active reference on the file. Because all the subsystem | |
215 | * files are drained before a css is disassociated with a cgroup, | |
216 | * the matching css from the cgroup's subsys table is guaranteed to | |
217 | * be and stay valid until the enclosing operation is complete. | |
218 | */ | |
219 | if (cft->ss) | |
220 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
221 | else | |
222 | return &cgrp->dummy_css; | |
59f5296b TH |
223 | } |
224 | EXPORT_SYMBOL_GPL(seq_css); | |
225 | ||
78574cf9 LZ |
226 | /** |
227 | * cgroup_is_descendant - test ancestry | |
228 | * @cgrp: the cgroup to be tested | |
229 | * @ancestor: possible ancestor of @cgrp | |
230 | * | |
231 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
232 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
233 | * and @ancestor are accessible. | |
234 | */ | |
235 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
236 | { | |
237 | while (cgrp) { | |
238 | if (cgrp == ancestor) | |
239 | return true; | |
240 | cgrp = cgrp->parent; | |
241 | } | |
242 | return false; | |
243 | } | |
ddbcc7e8 | 244 | |
e9685a03 | 245 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
246 | { |
247 | const int bits = | |
bd89aabc PM |
248 | (1 << CGRP_RELEASABLE) | |
249 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
250 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
251 | } |
252 | ||
e9685a03 | 253 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 254 | { |
bd89aabc | 255 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
256 | } |
257 | ||
1c6727af TH |
258 | /** |
259 | * for_each_css - iterate all css's of a cgroup | |
260 | * @css: the iteration cursor | |
261 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
262 | * @cgrp: the target cgroup to iterate css's of | |
263 | * | |
264 | * Should be called under cgroup_mutex. | |
265 | */ | |
266 | #define for_each_css(css, ssid, cgrp) \ | |
267 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
268 | if (!((css) = rcu_dereference_check( \ | |
269 | (cgrp)->subsys[(ssid)], \ | |
ace2bee8 | 270 | lockdep_is_held(&cgroup_tree_mutex) || \ |
1c6727af TH |
271 | lockdep_is_held(&cgroup_mutex)))) { } \ |
272 | else | |
273 | ||
30159ec7 | 274 | /** |
3ed80a62 | 275 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 276 | * @ss: the iteration cursor |
780cd8b3 | 277 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 278 | */ |
780cd8b3 | 279 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
280 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
281 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 282 | |
5549c497 TH |
283 | /* iterate across the active hierarchies */ |
284 | #define for_each_active_root(root) \ | |
285 | list_for_each_entry((root), &cgroup_roots, root_list) | |
ddbcc7e8 | 286 | |
7ae1bad9 TH |
287 | /** |
288 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
289 | * @cgrp: the cgroup to be checked for liveness | |
290 | * | |
47cfcd09 TH |
291 | * On success, returns true; the mutex should be later unlocked. On |
292 | * failure returns false with no lock held. | |
7ae1bad9 | 293 | */ |
b9777cf8 | 294 | static bool cgroup_lock_live_group(struct cgroup *cgrp) |
7ae1bad9 TH |
295 | { |
296 | mutex_lock(&cgroup_mutex); | |
54766d4a | 297 | if (cgroup_is_dead(cgrp)) { |
7ae1bad9 TH |
298 | mutex_unlock(&cgroup_mutex); |
299 | return false; | |
300 | } | |
301 | return true; | |
302 | } | |
7ae1bad9 | 303 | |
81a6a5cd PM |
304 | /* the list of cgroups eligible for automatic release. Protected by |
305 | * release_list_lock */ | |
306 | static LIST_HEAD(release_list); | |
cdcc136f | 307 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
308 | static void cgroup_release_agent(struct work_struct *work); |
309 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 310 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 311 | |
69d0206c TH |
312 | /* |
313 | * A cgroup can be associated with multiple css_sets as different tasks may | |
314 | * belong to different cgroups on different hierarchies. In the other | |
315 | * direction, a css_set is naturally associated with multiple cgroups. | |
316 | * This M:N relationship is represented by the following link structure | |
317 | * which exists for each association and allows traversing the associations | |
318 | * from both sides. | |
319 | */ | |
320 | struct cgrp_cset_link { | |
321 | /* the cgroup and css_set this link associates */ | |
322 | struct cgroup *cgrp; | |
323 | struct css_set *cset; | |
324 | ||
325 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
326 | struct list_head cset_link; | |
327 | ||
328 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
329 | struct list_head cgrp_link; | |
817929ec PM |
330 | }; |
331 | ||
332 | /* The default css_set - used by init and its children prior to any | |
333 | * hierarchies being mounted. It contains a pointer to the root state | |
334 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
335 | * reference-counted, to improve performance when child cgroups | |
336 | * haven't been created. | |
337 | */ | |
338 | ||
339 | static struct css_set init_css_set; | |
69d0206c | 340 | static struct cgrp_cset_link init_cgrp_cset_link; |
817929ec | 341 | |
0942eeee | 342 | /* |
96d365e0 TH |
343 | * css_set_rwsem protects the list of css_set objects, and the chain of |
344 | * tasks off each css_set. | |
0942eeee | 345 | */ |
96d365e0 | 346 | static DECLARE_RWSEM(css_set_rwsem); |
817929ec PM |
347 | static int css_set_count; |
348 | ||
7717f7ba PM |
349 | /* |
350 | * hash table for cgroup groups. This improves the performance to find | |
351 | * an existing css_set. This hash doesn't (currently) take into | |
352 | * account cgroups in empty hierarchies. | |
353 | */ | |
472b1053 | 354 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 355 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 356 | |
0ac801fe | 357 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 358 | { |
0ac801fe | 359 | unsigned long key = 0UL; |
30159ec7 TH |
360 | struct cgroup_subsys *ss; |
361 | int i; | |
472b1053 | 362 | |
30159ec7 | 363 | for_each_subsys(ss, i) |
0ac801fe LZ |
364 | key += (unsigned long)css[i]; |
365 | key = (key >> 16) ^ key; | |
472b1053 | 366 | |
0ac801fe | 367 | return key; |
472b1053 LZ |
368 | } |
369 | ||
89c5509b | 370 | static void put_css_set_locked(struct css_set *cset, bool taskexit) |
b4f48b63 | 371 | { |
69d0206c | 372 | struct cgrp_cset_link *link, *tmp_link; |
5abb8855 | 373 | |
89c5509b TH |
374 | lockdep_assert_held(&css_set_rwsem); |
375 | ||
376 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 377 | return; |
81a6a5cd | 378 | |
2c6ab6d2 | 379 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
5abb8855 | 380 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
381 | css_set_count--; |
382 | ||
69d0206c | 383 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 384 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 385 | |
69d0206c TH |
386 | list_del(&link->cset_link); |
387 | list_del(&link->cgrp_link); | |
71b5707e | 388 | |
96d365e0 | 389 | /* @cgrp can't go away while we're holding css_set_rwsem */ |
6f3d828f | 390 | if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { |
81a6a5cd | 391 | if (taskexit) |
bd89aabc PM |
392 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
393 | check_for_release(cgrp); | |
81a6a5cd | 394 | } |
2c6ab6d2 PM |
395 | |
396 | kfree(link); | |
81a6a5cd | 397 | } |
2c6ab6d2 | 398 | |
5abb8855 | 399 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
400 | } |
401 | ||
89c5509b TH |
402 | static void put_css_set(struct css_set *cset, bool taskexit) |
403 | { | |
404 | /* | |
405 | * Ensure that the refcount doesn't hit zero while any readers | |
406 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
407 | * rwlock | |
408 | */ | |
409 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
410 | return; | |
411 | ||
412 | down_write(&css_set_rwsem); | |
413 | put_css_set_locked(cset, taskexit); | |
414 | up_write(&css_set_rwsem); | |
415 | } | |
416 | ||
817929ec PM |
417 | /* |
418 | * refcounted get/put for css_set objects | |
419 | */ | |
5abb8855 | 420 | static inline void get_css_set(struct css_set *cset) |
817929ec | 421 | { |
5abb8855 | 422 | atomic_inc(&cset->refcount); |
817929ec PM |
423 | } |
424 | ||
b326f9d0 | 425 | /** |
7717f7ba | 426 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
427 | * @cset: candidate css_set being tested |
428 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
429 | * @new_cgrp: cgroup that's being entered by the task |
430 | * @template: desired set of css pointers in css_set (pre-calculated) | |
431 | * | |
6f4b7e63 | 432 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
433 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
434 | */ | |
5abb8855 TH |
435 | static bool compare_css_sets(struct css_set *cset, |
436 | struct css_set *old_cset, | |
7717f7ba PM |
437 | struct cgroup *new_cgrp, |
438 | struct cgroup_subsys_state *template[]) | |
439 | { | |
440 | struct list_head *l1, *l2; | |
441 | ||
5abb8855 | 442 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) { |
7717f7ba PM |
443 | /* Not all subsystems matched */ |
444 | return false; | |
445 | } | |
446 | ||
447 | /* | |
448 | * Compare cgroup pointers in order to distinguish between | |
449 | * different cgroups in heirarchies with no subsystems. We | |
450 | * could get by with just this check alone (and skip the | |
451 | * memcmp above) but on most setups the memcmp check will | |
452 | * avoid the need for this more expensive check on almost all | |
453 | * candidates. | |
454 | */ | |
455 | ||
69d0206c TH |
456 | l1 = &cset->cgrp_links; |
457 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 458 | while (1) { |
69d0206c | 459 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 460 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
461 | |
462 | l1 = l1->next; | |
463 | l2 = l2->next; | |
464 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
465 | if (l1 == &cset->cgrp_links) { |
466 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
467 | break; |
468 | } else { | |
69d0206c | 469 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
470 | } |
471 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
472 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
473 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
474 | cgrp1 = link1->cgrp; | |
475 | cgrp2 = link2->cgrp; | |
7717f7ba | 476 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 477 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
478 | |
479 | /* | |
480 | * If this hierarchy is the hierarchy of the cgroup | |
481 | * that's changing, then we need to check that this | |
482 | * css_set points to the new cgroup; if it's any other | |
483 | * hierarchy, then this css_set should point to the | |
484 | * same cgroup as the old css_set. | |
485 | */ | |
5abb8855 TH |
486 | if (cgrp1->root == new_cgrp->root) { |
487 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
488 | return false; |
489 | } else { | |
5abb8855 | 490 | if (cgrp1 != cgrp2) |
7717f7ba PM |
491 | return false; |
492 | } | |
493 | } | |
494 | return true; | |
495 | } | |
496 | ||
b326f9d0 TH |
497 | /** |
498 | * find_existing_css_set - init css array and find the matching css_set | |
499 | * @old_cset: the css_set that we're using before the cgroup transition | |
500 | * @cgrp: the cgroup that we're moving into | |
501 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 502 | */ |
5abb8855 TH |
503 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
504 | struct cgroup *cgrp, | |
505 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 506 | { |
bd89aabc | 507 | struct cgroupfs_root *root = cgrp->root; |
30159ec7 | 508 | struct cgroup_subsys *ss; |
5abb8855 | 509 | struct css_set *cset; |
0ac801fe | 510 | unsigned long key; |
b326f9d0 | 511 | int i; |
817929ec | 512 | |
aae8aab4 BB |
513 | /* |
514 | * Build the set of subsystem state objects that we want to see in the | |
515 | * new css_set. while subsystems can change globally, the entries here | |
516 | * won't change, so no need for locking. | |
517 | */ | |
30159ec7 | 518 | for_each_subsys(ss, i) { |
a1a71b45 | 519 | if (root->subsys_mask & (1UL << i)) { |
817929ec PM |
520 | /* Subsystem is in this hierarchy. So we want |
521 | * the subsystem state from the new | |
522 | * cgroup */ | |
ca8bdcaf | 523 | template[i] = cgroup_css(cgrp, ss); |
817929ec PM |
524 | } else { |
525 | /* Subsystem is not in this hierarchy, so we | |
526 | * don't want to change the subsystem state */ | |
5abb8855 | 527 | template[i] = old_cset->subsys[i]; |
817929ec PM |
528 | } |
529 | } | |
530 | ||
0ac801fe | 531 | key = css_set_hash(template); |
5abb8855 TH |
532 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
533 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
534 | continue; |
535 | ||
536 | /* This css_set matches what we need */ | |
5abb8855 | 537 | return cset; |
472b1053 | 538 | } |
817929ec PM |
539 | |
540 | /* No existing cgroup group matched */ | |
541 | return NULL; | |
542 | } | |
543 | ||
69d0206c | 544 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 545 | { |
69d0206c | 546 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 547 | |
69d0206c TH |
548 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
549 | list_del(&link->cset_link); | |
36553434 LZ |
550 | kfree(link); |
551 | } | |
552 | } | |
553 | ||
69d0206c TH |
554 | /** |
555 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
556 | * @count: the number of links to allocate | |
557 | * @tmp_links: list_head the allocated links are put on | |
558 | * | |
559 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
560 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 561 | */ |
69d0206c | 562 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 563 | { |
69d0206c | 564 | struct cgrp_cset_link *link; |
817929ec | 565 | int i; |
69d0206c TH |
566 | |
567 | INIT_LIST_HEAD(tmp_links); | |
568 | ||
817929ec | 569 | for (i = 0; i < count; i++) { |
f4f4be2b | 570 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 571 | if (!link) { |
69d0206c | 572 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
573 | return -ENOMEM; |
574 | } | |
69d0206c | 575 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
576 | } |
577 | return 0; | |
578 | } | |
579 | ||
c12f65d4 LZ |
580 | /** |
581 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 582 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 583 | * @cset: the css_set to be linked |
c12f65d4 LZ |
584 | * @cgrp: the destination cgroup |
585 | */ | |
69d0206c TH |
586 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
587 | struct cgroup *cgrp) | |
c12f65d4 | 588 | { |
69d0206c | 589 | struct cgrp_cset_link *link; |
c12f65d4 | 590 | |
69d0206c TH |
591 | BUG_ON(list_empty(tmp_links)); |
592 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); | |
593 | link->cset = cset; | |
7717f7ba | 594 | link->cgrp = cgrp; |
69d0206c | 595 | list_move(&link->cset_link, &cgrp->cset_links); |
7717f7ba PM |
596 | /* |
597 | * Always add links to the tail of the list so that the list | |
598 | * is sorted by order of hierarchy creation | |
599 | */ | |
69d0206c | 600 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
601 | } |
602 | ||
b326f9d0 TH |
603 | /** |
604 | * find_css_set - return a new css_set with one cgroup updated | |
605 | * @old_cset: the baseline css_set | |
606 | * @cgrp: the cgroup to be updated | |
607 | * | |
608 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
609 | * substituted into the appropriate hierarchy. | |
817929ec | 610 | */ |
5abb8855 TH |
611 | static struct css_set *find_css_set(struct css_set *old_cset, |
612 | struct cgroup *cgrp) | |
817929ec | 613 | { |
b326f9d0 | 614 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 615 | struct css_set *cset; |
69d0206c TH |
616 | struct list_head tmp_links; |
617 | struct cgrp_cset_link *link; | |
0ac801fe | 618 | unsigned long key; |
472b1053 | 619 | |
b326f9d0 TH |
620 | lockdep_assert_held(&cgroup_mutex); |
621 | ||
817929ec PM |
622 | /* First see if we already have a cgroup group that matches |
623 | * the desired set */ | |
96d365e0 | 624 | down_read(&css_set_rwsem); |
5abb8855 TH |
625 | cset = find_existing_css_set(old_cset, cgrp, template); |
626 | if (cset) | |
627 | get_css_set(cset); | |
96d365e0 | 628 | up_read(&css_set_rwsem); |
817929ec | 629 | |
5abb8855 TH |
630 | if (cset) |
631 | return cset; | |
817929ec | 632 | |
f4f4be2b | 633 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 634 | if (!cset) |
817929ec PM |
635 | return NULL; |
636 | ||
69d0206c | 637 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 638 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 639 | kfree(cset); |
817929ec PM |
640 | return NULL; |
641 | } | |
642 | ||
5abb8855 | 643 | atomic_set(&cset->refcount, 1); |
69d0206c | 644 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 645 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 646 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 647 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 648 | INIT_LIST_HEAD(&cset->mg_node); |
5abb8855 | 649 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
650 | |
651 | /* Copy the set of subsystem state objects generated in | |
652 | * find_existing_css_set() */ | |
5abb8855 | 653 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 654 | |
96d365e0 | 655 | down_write(&css_set_rwsem); |
817929ec | 656 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 657 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 658 | struct cgroup *c = link->cgrp; |
69d0206c | 659 | |
7717f7ba PM |
660 | if (c->root == cgrp->root) |
661 | c = cgrp; | |
69d0206c | 662 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 663 | } |
817929ec | 664 | |
69d0206c | 665 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 666 | |
817929ec | 667 | css_set_count++; |
472b1053 LZ |
668 | |
669 | /* Add this cgroup group to the hash table */ | |
5abb8855 TH |
670 | key = css_set_hash(cset->subsys); |
671 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 672 | |
96d365e0 | 673 | up_write(&css_set_rwsem); |
817929ec | 674 | |
5abb8855 | 675 | return cset; |
b4f48b63 PM |
676 | } |
677 | ||
2bd59d48 TH |
678 | static struct cgroupfs_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
679 | { | |
680 | struct cgroup *top_cgrp = kf_root->kn->priv; | |
681 | ||
682 | return top_cgrp->root; | |
683 | } | |
684 | ||
f2e85d57 TH |
685 | static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end) |
686 | { | |
687 | int id; | |
688 | ||
689 | lockdep_assert_held(&cgroup_mutex); | |
690 | ||
691 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end, | |
692 | GFP_KERNEL); | |
693 | if (id < 0) | |
694 | return id; | |
695 | ||
696 | root->hierarchy_id = id; | |
697 | return 0; | |
698 | } | |
699 | ||
700 | static void cgroup_exit_root_id(struct cgroupfs_root *root) | |
701 | { | |
702 | lockdep_assert_held(&cgroup_mutex); | |
703 | ||
704 | if (root->hierarchy_id) { | |
705 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
706 | root->hierarchy_id = 0; | |
707 | } | |
708 | } | |
709 | ||
710 | static void cgroup_free_root(struct cgroupfs_root *root) | |
711 | { | |
712 | if (root) { | |
713 | /* hierarhcy ID shoulid already have been released */ | |
714 | WARN_ON_ONCE(root->hierarchy_id); | |
715 | ||
716 | idr_destroy(&root->cgroup_idr); | |
717 | kfree(root); | |
718 | } | |
719 | } | |
720 | ||
776f02fa | 721 | static void cgroup_destroy_root(struct cgroupfs_root *root) |
59f5296b | 722 | { |
f2e85d57 TH |
723 | struct cgroup *cgrp = &root->top_cgroup; |
724 | struct cgrp_cset_link *link, *tmp_link; | |
f2e85d57 | 725 | |
2bd59d48 | 726 | mutex_lock(&cgroup_tree_mutex); |
2bd59d48 | 727 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 728 | |
776f02fa | 729 | BUG_ON(atomic_read(&root->nr_cgrps)); |
f2e85d57 TH |
730 | BUG_ON(!list_empty(&cgrp->children)); |
731 | ||
f2e85d57 | 732 | /* Rebind all subsystems back to the default hierarchy */ |
35585573 | 733 | WARN_ON(rebind_subsystems(root, 0, root->subsys_mask)); |
f2e85d57 TH |
734 | |
735 | /* | |
736 | * Release all the links from cset_links to this hierarchy's | |
737 | * root cgroup | |
738 | */ | |
96d365e0 | 739 | down_write(&css_set_rwsem); |
f2e85d57 TH |
740 | |
741 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
742 | list_del(&link->cset_link); | |
743 | list_del(&link->cgrp_link); | |
744 | kfree(link); | |
745 | } | |
96d365e0 | 746 | up_write(&css_set_rwsem); |
f2e85d57 TH |
747 | |
748 | if (!list_empty(&root->root_list)) { | |
749 | list_del(&root->root_list); | |
750 | cgroup_root_count--; | |
751 | } | |
752 | ||
753 | cgroup_exit_root_id(root); | |
754 | ||
755 | mutex_unlock(&cgroup_mutex); | |
756 | mutex_unlock(&cgroup_tree_mutex); | |
f2e85d57 | 757 | |
2bd59d48 | 758 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
759 | cgroup_free_root(root); |
760 | } | |
761 | ||
ceb6a081 TH |
762 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
763 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
7717f7ba PM |
764 | struct cgroupfs_root *root) |
765 | { | |
7717f7ba PM |
766 | struct cgroup *res = NULL; |
767 | ||
96d365e0 TH |
768 | lockdep_assert_held(&cgroup_mutex); |
769 | lockdep_assert_held(&css_set_rwsem); | |
770 | ||
5abb8855 | 771 | if (cset == &init_css_set) { |
7717f7ba PM |
772 | res = &root->top_cgroup; |
773 | } else { | |
69d0206c TH |
774 | struct cgrp_cset_link *link; |
775 | ||
776 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 777 | struct cgroup *c = link->cgrp; |
69d0206c | 778 | |
7717f7ba PM |
779 | if (c->root == root) { |
780 | res = c; | |
781 | break; | |
782 | } | |
783 | } | |
784 | } | |
96d365e0 | 785 | |
7717f7ba PM |
786 | BUG_ON(!res); |
787 | return res; | |
788 | } | |
789 | ||
ceb6a081 TH |
790 | /* |
791 | * Return the cgroup for "task" from the given hierarchy. Must be | |
792 | * called with cgroup_mutex and css_set_rwsem held. | |
793 | */ | |
794 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
795 | struct cgroupfs_root *root) | |
796 | { | |
797 | /* | |
798 | * No need to lock the task - since we hold cgroup_mutex the | |
799 | * task can't change groups, so the only thing that can happen | |
800 | * is that it exits and its css is set back to init_css_set. | |
801 | */ | |
802 | return cset_cgroup_from_root(task_css_set(task), root); | |
803 | } | |
804 | ||
ddbcc7e8 PM |
805 | /* |
806 | * There is one global cgroup mutex. We also require taking | |
807 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
808 | * See "The task_lock() exception", at the end of this comment. | |
809 | * | |
810 | * A task must hold cgroup_mutex to modify cgroups. | |
811 | * | |
812 | * Any task can increment and decrement the count field without lock. | |
813 | * So in general, code holding cgroup_mutex can't rely on the count | |
814 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 815 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
816 | * means that no tasks are currently attached, therefore there is no |
817 | * way a task attached to that cgroup can fork (the other way to | |
818 | * increment the count). So code holding cgroup_mutex can safely | |
819 | * assume that if the count is zero, it will stay zero. Similarly, if | |
820 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
821 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
822 | * needs that mutex. | |
823 | * | |
ddbcc7e8 PM |
824 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
825 | * (usually) take cgroup_mutex. These are the two most performance | |
826 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
827 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
828 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
829 | * to the release agent with the name of the cgroup (path relative to |
830 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
831 | * |
832 | * A cgroup can only be deleted if both its 'count' of using tasks | |
833 | * is zero, and its list of 'children' cgroups is empty. Since all | |
834 | * tasks in the system use _some_ cgroup, and since there is always at | |
835 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
836 | * always has either children cgroups and/or using tasks. So we don't | |
837 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
838 | * | |
839 | * The task_lock() exception | |
840 | * | |
841 | * The need for this exception arises from the action of | |
d0b2fdd2 | 842 | * cgroup_attach_task(), which overwrites one task's cgroup pointer with |
a043e3b2 | 843 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
844 | * several performance critical places that need to reference |
845 | * task->cgroup without the expense of grabbing a system global | |
846 | * mutex. Therefore except as noted below, when dereferencing or, as | |
d0b2fdd2 | 847 | * in cgroup_attach_task(), modifying a task's cgroup pointer we use |
ddbcc7e8 PM |
848 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
849 | * the task_struct routinely used for such matters. | |
850 | * | |
851 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 852 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
853 | */ |
854 | ||
628f7cd4 | 855 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); |
2bd59d48 | 856 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 857 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 858 | |
8d7e6fb0 TH |
859 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
860 | char *buf) | |
861 | { | |
862 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && | |
863 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
864 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
865 | cft->ss->name, cft->name); | |
866 | else | |
867 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
868 | return buf; | |
869 | } | |
870 | ||
f2e85d57 TH |
871 | /** |
872 | * cgroup_file_mode - deduce file mode of a control file | |
873 | * @cft: the control file in question | |
874 | * | |
875 | * returns cft->mode if ->mode is not 0 | |
876 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
877 | * returns S_IRUGO if it has only a read handler | |
878 | * returns S_IWUSR if it has only a write hander | |
879 | */ | |
880 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
881 | { | |
882 | umode_t mode = 0; | |
883 | ||
884 | if (cft->mode) | |
885 | return cft->mode; | |
886 | ||
887 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) | |
888 | mode |= S_IRUGO; | |
889 | ||
890 | if (cft->write_u64 || cft->write_s64 || cft->write_string || | |
891 | cft->trigger) | |
892 | mode |= S_IWUSR; | |
893 | ||
894 | return mode; | |
895 | } | |
896 | ||
be445626 LZ |
897 | static void cgroup_free_fn(struct work_struct *work) |
898 | { | |
ea15f8cc | 899 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); |
be445626 | 900 | |
3c9c825b | 901 | atomic_dec(&cgrp->root->nr_cgrps); |
b1a21367 | 902 | cgroup_pidlist_destroy_all(cgrp); |
be445626 | 903 | |
776f02fa TH |
904 | if (cgrp->parent) { |
905 | /* | |
906 | * We get a ref to the parent, and put the ref when this | |
907 | * cgroup is being freed, so it's guaranteed that the | |
908 | * parent won't be destroyed before its children. | |
909 | */ | |
910 | cgroup_put(cgrp->parent); | |
911 | kernfs_put(cgrp->kn); | |
912 | kfree(cgrp); | |
913 | } else { | |
914 | /* | |
915 | * This is top cgroup's refcnt reaching zero, which | |
916 | * indicates that the root should be released. | |
917 | */ | |
918 | cgroup_destroy_root(cgrp->root); | |
919 | } | |
be445626 LZ |
920 | } |
921 | ||
922 | static void cgroup_free_rcu(struct rcu_head *head) | |
923 | { | |
924 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); | |
925 | ||
ea15f8cc | 926 | INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); |
e5fca243 | 927 | queue_work(cgroup_destroy_wq, &cgrp->destroy_work); |
be445626 LZ |
928 | } |
929 | ||
59f5296b TH |
930 | static void cgroup_get(struct cgroup *cgrp) |
931 | { | |
2bd59d48 TH |
932 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
933 | WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0); | |
934 | atomic_inc(&cgrp->refcnt); | |
ddbcc7e8 PM |
935 | } |
936 | ||
59f5296b TH |
937 | static void cgroup_put(struct cgroup *cgrp) |
938 | { | |
2bd59d48 TH |
939 | if (!atomic_dec_and_test(&cgrp->refcnt)) |
940 | return; | |
776f02fa | 941 | if (WARN_ON_ONCE(cgrp->parent && !cgroup_is_dead(cgrp))) |
2bd59d48 | 942 | return; |
59f5296b | 943 | |
2bd59d48 TH |
944 | /* |
945 | * XXX: cgrp->id is only used to look up css's. As cgroup and | |
946 | * css's lifetimes will be decoupled, it should be made | |
947 | * per-subsystem and moved to css->id so that lookups are | |
948 | * successful until the target css is released. | |
949 | */ | |
950 | mutex_lock(&cgroup_mutex); | |
951 | idr_remove(&cgrp->root->cgroup_idr, cgrp->id); | |
952 | mutex_unlock(&cgroup_mutex); | |
953 | cgrp->id = -1; | |
ddbcc7e8 | 954 | |
2bd59d48 | 955 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
ddbcc7e8 PM |
956 | } |
957 | ||
2739d3cc | 958 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 959 | { |
2bd59d48 | 960 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 961 | |
ace2bee8 | 962 | lockdep_assert_held(&cgroup_tree_mutex); |
2bd59d48 | 963 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
964 | } |
965 | ||
13af07df | 966 | /** |
628f7cd4 | 967 | * cgroup_clear_dir - remove subsys files in a cgroup directory |
8f89140a | 968 | * @cgrp: target cgroup |
13af07df AR |
969 | * @subsys_mask: mask of the subsystem ids whose files should be removed |
970 | */ | |
628f7cd4 | 971 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
05ef1d7c | 972 | { |
13af07df | 973 | struct cgroup_subsys *ss; |
b420ba7d | 974 | int i; |
05ef1d7c | 975 | |
b420ba7d | 976 | for_each_subsys(ss, i) { |
0adb0704 | 977 | struct cftype *cfts; |
b420ba7d TH |
978 | |
979 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 980 | continue; |
0adb0704 TH |
981 | list_for_each_entry(cfts, &ss->cfts, node) |
982 | cgroup_addrm_files(cgrp, cfts, false); | |
13af07df | 983 | } |
ddbcc7e8 PM |
984 | } |
985 | ||
ddbcc7e8 | 986 | static int rebind_subsystems(struct cgroupfs_root *root, |
a8a648c4 | 987 | unsigned long added_mask, unsigned removed_mask) |
ddbcc7e8 | 988 | { |
bd89aabc | 989 | struct cgroup *cgrp = &root->top_cgroup; |
30159ec7 | 990 | struct cgroup_subsys *ss; |
3126121f | 991 | int i, ret; |
ddbcc7e8 | 992 | |
ace2bee8 TH |
993 | lockdep_assert_held(&cgroup_tree_mutex); |
994 | lockdep_assert_held(&cgroup_mutex); | |
aae8aab4 | 995 | |
ddbcc7e8 | 996 | /* Check that any added subsystems are currently free */ |
3ed80a62 TH |
997 | for_each_subsys(ss, i) |
998 | if ((added_mask & (1 << i)) && ss->root != &cgroup_dummy_root) | |
999 | return -EBUSY; | |
ddbcc7e8 | 1000 | |
3126121f TH |
1001 | ret = cgroup_populate_dir(cgrp, added_mask); |
1002 | if (ret) | |
3ed80a62 | 1003 | return ret; |
3126121f TH |
1004 | |
1005 | /* | |
1006 | * Nothing can fail from this point on. Remove files for the | |
1007 | * removed subsystems and rebind each subsystem. | |
1008 | */ | |
4ac06017 | 1009 | mutex_unlock(&cgroup_mutex); |
3126121f | 1010 | cgroup_clear_dir(cgrp, removed_mask); |
4ac06017 | 1011 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1012 | |
30159ec7 | 1013 | for_each_subsys(ss, i) { |
ddbcc7e8 | 1014 | unsigned long bit = 1UL << i; |
30159ec7 | 1015 | |
a1a71b45 | 1016 | if (bit & added_mask) { |
ddbcc7e8 | 1017 | /* We're binding this subsystem to this hierarchy */ |
ca8bdcaf TH |
1018 | BUG_ON(cgroup_css(cgrp, ss)); |
1019 | BUG_ON(!cgroup_css(cgroup_dummy_top, ss)); | |
1020 | BUG_ON(cgroup_css(cgroup_dummy_top, ss)->cgroup != cgroup_dummy_top); | |
a8a648c4 | 1021 | |
73e80ed8 | 1022 | rcu_assign_pointer(cgrp->subsys[i], |
ca8bdcaf TH |
1023 | cgroup_css(cgroup_dummy_top, ss)); |
1024 | cgroup_css(cgrp, ss)->cgroup = cgrp; | |
a8a648c4 | 1025 | |
b2aa30f7 | 1026 | ss->root = root; |
ddbcc7e8 | 1027 | if (ss->bind) |
ca8bdcaf | 1028 | ss->bind(cgroup_css(cgrp, ss)); |
a8a648c4 | 1029 | |
cf5d5941 | 1030 | /* refcount was already taken, and we're keeping it */ |
a8a648c4 | 1031 | root->subsys_mask |= bit; |
a1a71b45 | 1032 | } else if (bit & removed_mask) { |
ddbcc7e8 | 1033 | /* We're removing this subsystem */ |
ca8bdcaf TH |
1034 | BUG_ON(cgroup_css(cgrp, ss) != cgroup_css(cgroup_dummy_top, ss)); |
1035 | BUG_ON(cgroup_css(cgrp, ss)->cgroup != cgrp); | |
a8a648c4 | 1036 | |
ddbcc7e8 | 1037 | if (ss->bind) |
ca8bdcaf | 1038 | ss->bind(cgroup_css(cgroup_dummy_top, ss)); |
73e80ed8 | 1039 | |
ca8bdcaf | 1040 | cgroup_css(cgroup_dummy_top, ss)->cgroup = cgroup_dummy_top; |
73e80ed8 TH |
1041 | RCU_INIT_POINTER(cgrp->subsys[i], NULL); |
1042 | ||
9871bf95 | 1043 | cgroup_subsys[i]->root = &cgroup_dummy_root; |
a8a648c4 | 1044 | root->subsys_mask &= ~bit; |
ddbcc7e8 PM |
1045 | } |
1046 | } | |
ddbcc7e8 | 1047 | |
2bd59d48 | 1048 | kernfs_activate(cgrp->kn); |
ddbcc7e8 PM |
1049 | return 0; |
1050 | } | |
1051 | ||
2bd59d48 TH |
1052 | static int cgroup_show_options(struct seq_file *seq, |
1053 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1054 | { |
2bd59d48 | 1055 | struct cgroupfs_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1056 | struct cgroup_subsys *ss; |
b85d2040 | 1057 | int ssid; |
ddbcc7e8 | 1058 | |
b85d2040 TH |
1059 | for_each_subsys(ss, ssid) |
1060 | if (root->subsys_mask & (1 << ssid)) | |
1061 | seq_printf(seq, ",%s", ss->name); | |
873fe09e TH |
1062 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) |
1063 | seq_puts(seq, ",sane_behavior"); | |
93438629 | 1064 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1065 | seq_puts(seq, ",noprefix"); |
93438629 | 1066 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1067 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1068 | |
1069 | spin_lock(&release_agent_path_lock); | |
81a6a5cd PM |
1070 | if (strlen(root->release_agent_path)) |
1071 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
69e943b7 TH |
1072 | spin_unlock(&release_agent_path_lock); |
1073 | ||
2260e7fc | 1074 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags)) |
97978e6d | 1075 | seq_puts(seq, ",clone_children"); |
c6d57f33 PM |
1076 | if (strlen(root->name)) |
1077 | seq_printf(seq, ",name=%s", root->name); | |
ddbcc7e8 PM |
1078 | return 0; |
1079 | } | |
1080 | ||
1081 | struct cgroup_sb_opts { | |
a1a71b45 | 1082 | unsigned long subsys_mask; |
ddbcc7e8 | 1083 | unsigned long flags; |
81a6a5cd | 1084 | char *release_agent; |
2260e7fc | 1085 | bool cpuset_clone_children; |
c6d57f33 | 1086 | char *name; |
2c6ab6d2 PM |
1087 | /* User explicitly requested empty subsystem */ |
1088 | bool none; | |
ddbcc7e8 PM |
1089 | }; |
1090 | ||
aae8aab4 | 1091 | /* |
9871bf95 TH |
1092 | * Convert a hierarchy specifier into a bitmask of subsystems and |
1093 | * flags. Call with cgroup_mutex held to protect the cgroup_subsys[] | |
1094 | * array. This function takes refcounts on subsystems to be used, unless it | |
1095 | * returns error, in which case no refcounts are taken. | |
aae8aab4 | 1096 | */ |
cf5d5941 | 1097 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1098 | { |
32a8cf23 DL |
1099 | char *token, *o = data; |
1100 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1101 | unsigned long mask = (unsigned long)-1; |
30159ec7 TH |
1102 | struct cgroup_subsys *ss; |
1103 | int i; | |
f9ab5b5b | 1104 | |
aae8aab4 BB |
1105 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1106 | ||
f9ab5b5b | 1107 | #ifdef CONFIG_CPUSETS |
073219e9 | 1108 | mask = ~(1UL << cpuset_cgrp_id); |
f9ab5b5b | 1109 | #endif |
ddbcc7e8 | 1110 | |
c6d57f33 | 1111 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1112 | |
1113 | while ((token = strsep(&o, ",")) != NULL) { | |
1114 | if (!*token) | |
1115 | return -EINVAL; | |
32a8cf23 | 1116 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1117 | /* Explicitly have no subsystems */ |
1118 | opts->none = true; | |
32a8cf23 DL |
1119 | continue; |
1120 | } | |
1121 | if (!strcmp(token, "all")) { | |
1122 | /* Mutually exclusive option 'all' + subsystem name */ | |
1123 | if (one_ss) | |
1124 | return -EINVAL; | |
1125 | all_ss = true; | |
1126 | continue; | |
1127 | } | |
873fe09e TH |
1128 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1129 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1130 | continue; | |
1131 | } | |
32a8cf23 | 1132 | if (!strcmp(token, "noprefix")) { |
93438629 | 1133 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1134 | continue; |
1135 | } | |
1136 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1137 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1138 | continue; |
1139 | } | |
03b1cde6 | 1140 | if (!strcmp(token, "xattr")) { |
93438629 | 1141 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1142 | continue; |
1143 | } | |
32a8cf23 | 1144 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1145 | /* Specifying two release agents is forbidden */ |
1146 | if (opts->release_agent) | |
1147 | return -EINVAL; | |
c6d57f33 | 1148 | opts->release_agent = |
e400c285 | 1149 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1150 | if (!opts->release_agent) |
1151 | return -ENOMEM; | |
32a8cf23 DL |
1152 | continue; |
1153 | } | |
1154 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1155 | const char *name = token + 5; |
1156 | /* Can't specify an empty name */ | |
1157 | if (!strlen(name)) | |
1158 | return -EINVAL; | |
1159 | /* Must match [\w.-]+ */ | |
1160 | for (i = 0; i < strlen(name); i++) { | |
1161 | char c = name[i]; | |
1162 | if (isalnum(c)) | |
1163 | continue; | |
1164 | if ((c == '.') || (c == '-') || (c == '_')) | |
1165 | continue; | |
1166 | return -EINVAL; | |
1167 | } | |
1168 | /* Specifying two names is forbidden */ | |
1169 | if (opts->name) | |
1170 | return -EINVAL; | |
1171 | opts->name = kstrndup(name, | |
e400c285 | 1172 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1173 | GFP_KERNEL); |
1174 | if (!opts->name) | |
1175 | return -ENOMEM; | |
32a8cf23 DL |
1176 | |
1177 | continue; | |
1178 | } | |
1179 | ||
30159ec7 | 1180 | for_each_subsys(ss, i) { |
32a8cf23 DL |
1181 | if (strcmp(token, ss->name)) |
1182 | continue; | |
1183 | if (ss->disabled) | |
1184 | continue; | |
1185 | ||
1186 | /* Mutually exclusive option 'all' + subsystem name */ | |
1187 | if (all_ss) | |
1188 | return -EINVAL; | |
a1a71b45 | 1189 | set_bit(i, &opts->subsys_mask); |
32a8cf23 DL |
1190 | one_ss = true; |
1191 | ||
1192 | break; | |
1193 | } | |
1194 | if (i == CGROUP_SUBSYS_COUNT) | |
1195 | return -ENOENT; | |
1196 | } | |
1197 | ||
1198 | /* | |
1199 | * If the 'all' option was specified select all the subsystems, | |
0d19ea86 LZ |
1200 | * otherwise if 'none', 'name=' and a subsystem name options |
1201 | * were not specified, let's default to 'all' | |
32a8cf23 | 1202 | */ |
30159ec7 TH |
1203 | if (all_ss || (!one_ss && !opts->none && !opts->name)) |
1204 | for_each_subsys(ss, i) | |
1205 | if (!ss->disabled) | |
1206 | set_bit(i, &opts->subsys_mask); | |
ddbcc7e8 | 1207 | |
2c6ab6d2 PM |
1208 | /* Consistency checks */ |
1209 | ||
873fe09e TH |
1210 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1211 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); | |
1212 | ||
d3ba07c3 TH |
1213 | if ((opts->flags & (CGRP_ROOT_NOPREFIX | CGRP_ROOT_XATTR)) || |
1214 | opts->cpuset_clone_children || opts->release_agent || | |
1215 | opts->name) { | |
1216 | pr_err("cgroup: sane_behavior: noprefix, xattr, clone_children, release_agent and name are not allowed\n"); | |
873fe09e TH |
1217 | return -EINVAL; |
1218 | } | |
873fe09e TH |
1219 | } |
1220 | ||
f9ab5b5b LZ |
1221 | /* |
1222 | * Option noprefix was introduced just for backward compatibility | |
1223 | * with the old cpuset, so we allow noprefix only if mounting just | |
1224 | * the cpuset subsystem. | |
1225 | */ | |
93438629 | 1226 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1227 | return -EINVAL; |
1228 | ||
2c6ab6d2 PM |
1229 | |
1230 | /* Can't specify "none" and some subsystems */ | |
a1a71b45 | 1231 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1232 | return -EINVAL; |
1233 | ||
1234 | /* | |
1235 | * We either have to specify by name or by subsystems. (So all | |
1236 | * empty hierarchies must have a name). | |
1237 | */ | |
a1a71b45 | 1238 | if (!opts->subsys_mask && !opts->name) |
ddbcc7e8 PM |
1239 | return -EINVAL; |
1240 | ||
1241 | return 0; | |
1242 | } | |
1243 | ||
2bd59d48 | 1244 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1245 | { |
1246 | int ret = 0; | |
2bd59d48 | 1247 | struct cgroupfs_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1248 | struct cgroup_sb_opts opts; |
a1a71b45 | 1249 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1250 | |
873fe09e TH |
1251 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1252 | pr_err("cgroup: sane_behavior: remount is not allowed\n"); | |
1253 | return -EINVAL; | |
1254 | } | |
1255 | ||
ace2bee8 | 1256 | mutex_lock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
1257 | mutex_lock(&cgroup_mutex); |
1258 | ||
1259 | /* See what subsystems are wanted */ | |
1260 | ret = parse_cgroupfs_options(data, &opts); | |
1261 | if (ret) | |
1262 | goto out_unlock; | |
1263 | ||
a8a648c4 | 1264 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
8b5a5a9d TH |
1265 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", |
1266 | task_tgid_nr(current), current->comm); | |
1267 | ||
a1a71b45 AR |
1268 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1269 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1270 | |
cf5d5941 | 1271 | /* Don't allow flags or name to change at remount */ |
0ce6cba3 | 1272 | if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) || |
cf5d5941 | 1273 | (opts.name && strcmp(opts.name, root->name))) { |
0ce6cba3 TH |
1274 | pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n", |
1275 | opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "", | |
1276 | root->flags & CGRP_ROOT_OPTION_MASK, root->name); | |
c6d57f33 PM |
1277 | ret = -EINVAL; |
1278 | goto out_unlock; | |
1279 | } | |
1280 | ||
f172e67c | 1281 | /* remounting is not allowed for populated hierarchies */ |
3c9c825b | 1282 | if (!list_empty(&root->top_cgroup.children)) { |
f172e67c | 1283 | ret = -EBUSY; |
0670e08b | 1284 | goto out_unlock; |
cf5d5941 | 1285 | } |
ddbcc7e8 | 1286 | |
a8a648c4 | 1287 | ret = rebind_subsystems(root, added_mask, removed_mask); |
3126121f | 1288 | if (ret) |
0670e08b | 1289 | goto out_unlock; |
ddbcc7e8 | 1290 | |
69e943b7 TH |
1291 | if (opts.release_agent) { |
1292 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1293 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1294 | spin_unlock(&release_agent_path_lock); |
1295 | } | |
ddbcc7e8 | 1296 | out_unlock: |
66bdc9cf | 1297 | kfree(opts.release_agent); |
c6d57f33 | 1298 | kfree(opts.name); |
ddbcc7e8 | 1299 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 1300 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
1301 | return ret; |
1302 | } | |
1303 | ||
afeb0f9f TH |
1304 | /* |
1305 | * To reduce the fork() overhead for systems that are not actually using | |
1306 | * their cgroups capability, we don't maintain the lists running through | |
1307 | * each css_set to its tasks until we see the list actually used - in other | |
1308 | * words after the first mount. | |
1309 | */ | |
1310 | static bool use_task_css_set_links __read_mostly; | |
1311 | ||
1312 | static void cgroup_enable_task_cg_lists(void) | |
1313 | { | |
1314 | struct task_struct *p, *g; | |
1315 | ||
96d365e0 | 1316 | down_write(&css_set_rwsem); |
afeb0f9f TH |
1317 | |
1318 | if (use_task_css_set_links) | |
1319 | goto out_unlock; | |
1320 | ||
1321 | use_task_css_set_links = true; | |
1322 | ||
1323 | /* | |
1324 | * We need tasklist_lock because RCU is not safe against | |
1325 | * while_each_thread(). Besides, a forking task that has passed | |
1326 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1327 | * is not guaranteed to have its child immediately visible in the | |
1328 | * tasklist if we walk through it with RCU. | |
1329 | */ | |
1330 | read_lock(&tasklist_lock); | |
1331 | do_each_thread(g, p) { | |
1332 | task_lock(p); | |
1333 | ||
1334 | WARN_ON_ONCE(!list_empty(&p->cg_list) || | |
1335 | task_css_set(p) != &init_css_set); | |
1336 | ||
1337 | /* | |
1338 | * We should check if the process is exiting, otherwise | |
1339 | * it will race with cgroup_exit() in that the list | |
1340 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1341 | * Do it while holding siglock so that we don't end up |
1342 | * racing against cgroup_exit(). | |
afeb0f9f | 1343 | */ |
f153ad11 | 1344 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1345 | if (!(p->flags & PF_EXITING)) { |
1346 | struct css_set *cset = task_css_set(p); | |
1347 | ||
1348 | list_add(&p->cg_list, &cset->tasks); | |
1349 | get_css_set(cset); | |
1350 | } | |
f153ad11 | 1351 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1352 | |
1353 | task_unlock(p); | |
1354 | } while_each_thread(g, p); | |
1355 | read_unlock(&tasklist_lock); | |
1356 | out_unlock: | |
96d365e0 | 1357 | up_write(&css_set_rwsem); |
afeb0f9f TH |
1358 | } |
1359 | ||
cc31edce PM |
1360 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1361 | { | |
2bd59d48 | 1362 | atomic_set(&cgrp->refcnt, 1); |
cc31edce PM |
1363 | INIT_LIST_HEAD(&cgrp->sibling); |
1364 | INIT_LIST_HEAD(&cgrp->children); | |
69d0206c | 1365 | INIT_LIST_HEAD(&cgrp->cset_links); |
cc31edce | 1366 | INIT_LIST_HEAD(&cgrp->release_list); |
72a8cb30 BB |
1367 | INIT_LIST_HEAD(&cgrp->pidlists); |
1368 | mutex_init(&cgrp->pidlist_mutex); | |
67f4c36f | 1369 | cgrp->dummy_css.cgroup = cgrp; |
cc31edce | 1370 | } |
c6d57f33 | 1371 | |
ddbcc7e8 PM |
1372 | static void init_cgroup_root(struct cgroupfs_root *root) |
1373 | { | |
bd89aabc | 1374 | struct cgroup *cgrp = &root->top_cgroup; |
b0ca5a84 | 1375 | |
ddbcc7e8 | 1376 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1377 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1378 | cgrp->root = root; |
cc31edce | 1379 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1380 | idr_init(&root->cgroup_idr); |
ddbcc7e8 PM |
1381 | } |
1382 | ||
c6d57f33 PM |
1383 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1384 | { | |
1385 | struct cgroupfs_root *root; | |
1386 | ||
a1a71b45 | 1387 | if (!opts->subsys_mask && !opts->none) |
2bd59d48 | 1388 | return ERR_PTR(-EINVAL); |
c6d57f33 PM |
1389 | |
1390 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1391 | if (!root) | |
1392 | return ERR_PTR(-ENOMEM); | |
1393 | ||
1394 | init_cgroup_root(root); | |
2c6ab6d2 | 1395 | |
c6d57f33 PM |
1396 | root->flags = opts->flags; |
1397 | if (opts->release_agent) | |
1398 | strcpy(root->release_agent_path, opts->release_agent); | |
1399 | if (opts->name) | |
1400 | strcpy(root->name, opts->name); | |
2260e7fc TH |
1401 | if (opts->cpuset_clone_children) |
1402 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1403 | return root; |
1404 | } | |
1405 | ||
35585573 | 1406 | static int cgroup_setup_root(struct cgroupfs_root *root, unsigned long ss_mask) |
d427dfeb TH |
1407 | { |
1408 | LIST_HEAD(tmp_links); | |
d427dfeb | 1409 | struct cgroup *root_cgrp = &root->top_cgroup; |
d427dfeb | 1410 | struct css_set *cset; |
d427dfeb TH |
1411 | int i, ret; |
1412 | ||
1413 | lockdep_assert_held(&cgroup_tree_mutex); | |
1414 | lockdep_assert_held(&cgroup_mutex); | |
d427dfeb TH |
1415 | |
1416 | ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL); | |
1417 | if (ret < 0) | |
2bd59d48 | 1418 | goto out; |
d427dfeb TH |
1419 | root_cgrp->id = ret; |
1420 | ||
d427dfeb | 1421 | /* |
96d365e0 | 1422 | * We're accessing css_set_count without locking css_set_rwsem here, |
d427dfeb TH |
1423 | * but that's OK - it can only be increased by someone holding |
1424 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1425 | * have some link structures left over | |
1426 | */ | |
1427 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1428 | if (ret) | |
2bd59d48 | 1429 | goto out; |
d427dfeb TH |
1430 | |
1431 | /* ID 0 is reserved for dummy root, 1 for unified hierarchy */ | |
1432 | ret = cgroup_init_root_id(root, 2, 0); | |
1433 | if (ret) | |
2bd59d48 | 1434 | goto out; |
d427dfeb | 1435 | |
2bd59d48 TH |
1436 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1437 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1438 | root_cgrp); | |
1439 | if (IS_ERR(root->kf_root)) { | |
1440 | ret = PTR_ERR(root->kf_root); | |
1441 | goto exit_root_id; | |
1442 | } | |
1443 | root_cgrp->kn = root->kf_root->kn; | |
d427dfeb TH |
1444 | |
1445 | ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true); | |
1446 | if (ret) | |
2bd59d48 | 1447 | goto destroy_root; |
d427dfeb | 1448 | |
35585573 | 1449 | ret = rebind_subsystems(root, ss_mask, 0); |
d427dfeb | 1450 | if (ret) |
2bd59d48 | 1451 | goto destroy_root; |
d427dfeb TH |
1452 | |
1453 | /* | |
1454 | * There must be no failure case after here, since rebinding takes | |
1455 | * care of subsystems' refcounts, which are explicitly dropped in | |
1456 | * the failure exit path. | |
1457 | */ | |
1458 | list_add(&root->root_list, &cgroup_roots); | |
1459 | cgroup_root_count++; | |
1460 | ||
1461 | /* | |
1462 | * Link the top cgroup in this hierarchy into all the css_set | |
1463 | * objects. | |
1464 | */ | |
96d365e0 | 1465 | down_write(&css_set_rwsem); |
d427dfeb TH |
1466 | hash_for_each(css_set_table, i, cset, hlist) |
1467 | link_css_set(&tmp_links, cset, root_cgrp); | |
96d365e0 | 1468 | up_write(&css_set_rwsem); |
d427dfeb TH |
1469 | |
1470 | BUG_ON(!list_empty(&root_cgrp->children)); | |
3c9c825b | 1471 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
d427dfeb | 1472 | |
2bd59d48 | 1473 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1474 | ret = 0; |
2bd59d48 | 1475 | goto out; |
d427dfeb | 1476 | |
2bd59d48 TH |
1477 | destroy_root: |
1478 | kernfs_destroy_root(root->kf_root); | |
1479 | root->kf_root = NULL; | |
1480 | exit_root_id: | |
d427dfeb | 1481 | cgroup_exit_root_id(root); |
2bd59d48 | 1482 | out: |
d427dfeb TH |
1483 | free_cgrp_cset_links(&tmp_links); |
1484 | return ret; | |
1485 | } | |
1486 | ||
f7e83571 | 1487 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1488 | int flags, const char *unused_dev_name, |
f7e83571 | 1489 | void *data) |
ddbcc7e8 | 1490 | { |
2bd59d48 | 1491 | struct cgroupfs_root *root; |
ddbcc7e8 | 1492 | struct cgroup_sb_opts opts; |
2bd59d48 | 1493 | struct dentry *dentry; |
8e30e2b8 | 1494 | int ret; |
56fde9e0 TH |
1495 | |
1496 | /* | |
1497 | * The first time anyone tries to mount a cgroup, enable the list | |
1498 | * linking each css_set to its tasks and fix up all existing tasks. | |
1499 | */ | |
1500 | if (!use_task_css_set_links) | |
1501 | cgroup_enable_task_cg_lists(); | |
776f02fa | 1502 | retry: |
8e30e2b8 | 1503 | mutex_lock(&cgroup_tree_mutex); |
aae8aab4 | 1504 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
1505 | |
1506 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 1507 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 1508 | if (ret) |
8e30e2b8 | 1509 | goto out_unlock; |
ddbcc7e8 | 1510 | |
2bd59d48 TH |
1511 | /* look for a matching existing root */ |
1512 | for_each_active_root(root) { | |
1513 | bool name_match = false; | |
ddbcc7e8 | 1514 | |
2bd59d48 TH |
1515 | /* |
1516 | * If we asked for a name then it must match. Also, if | |
1517 | * name matches but sybsys_mask doesn't, we should fail. | |
1518 | * Remember whether name matched. | |
1519 | */ | |
1520 | if (opts.name) { | |
1521 | if (strcmp(opts.name, root->name)) | |
1522 | continue; | |
1523 | name_match = true; | |
1524 | } | |
ddbcc7e8 | 1525 | |
c6d57f33 | 1526 | /* |
2bd59d48 TH |
1527 | * If we asked for subsystems (or explicitly for no |
1528 | * subsystems) then they must match. | |
c6d57f33 | 1529 | */ |
2bd59d48 TH |
1530 | if ((opts.subsys_mask || opts.none) && |
1531 | (opts.subsys_mask != root->subsys_mask)) { | |
1532 | if (!name_match) | |
1533 | continue; | |
1534 | ret = -EBUSY; | |
1535 | goto out_unlock; | |
1536 | } | |
873fe09e | 1537 | |
c7ba8287 | 1538 | if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) { |
2a0ff3fb JL |
1539 | if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { |
1540 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); | |
1541 | ret = -EINVAL; | |
8e30e2b8 | 1542 | goto out_unlock; |
2a0ff3fb JL |
1543 | } else { |
1544 | pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); | |
1545 | } | |
873fe09e | 1546 | } |
2bd59d48 | 1547 | |
776f02fa TH |
1548 | /* |
1549 | * A root's lifetime is governed by its top cgroup. Zero | |
1550 | * ref indicate that the root is being destroyed. Wait for | |
1551 | * destruction to complete so that the subsystems are free. | |
1552 | * We can use wait_queue for the wait but this path is | |
1553 | * super cold. Let's just sleep for a bit and retry. | |
1554 | */ | |
1555 | if (!atomic_inc_not_zero(&root->top_cgroup.refcnt)) { | |
1556 | mutex_unlock(&cgroup_mutex); | |
1557 | mutex_unlock(&cgroup_tree_mutex); | |
6534fd6c LZ |
1558 | kfree(opts.release_agent); |
1559 | kfree(opts.name); | |
776f02fa TH |
1560 | msleep(10); |
1561 | goto retry; | |
1562 | } | |
1563 | ||
1564 | ret = 0; | |
2bd59d48 | 1565 | goto out_unlock; |
ddbcc7e8 PM |
1566 | } |
1567 | ||
2bd59d48 TH |
1568 | /* no such thing, create a new one */ |
1569 | root = cgroup_root_from_opts(&opts); | |
1570 | if (IS_ERR(root)) { | |
1571 | ret = PTR_ERR(root); | |
1572 | goto out_unlock; | |
1573 | } | |
1574 | ||
35585573 | 1575 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
1576 | if (ret) |
1577 | cgroup_free_root(root); | |
1578 | ||
8e30e2b8 | 1579 | out_unlock: |
e25e2cbb | 1580 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 1581 | mutex_unlock(&cgroup_tree_mutex); |
8e30e2b8 | 1582 | |
c6d57f33 PM |
1583 | kfree(opts.release_agent); |
1584 | kfree(opts.name); | |
8e30e2b8 | 1585 | |
2bd59d48 | 1586 | if (ret) |
8e30e2b8 | 1587 | return ERR_PTR(ret); |
2bd59d48 TH |
1588 | |
1589 | dentry = kernfs_mount(fs_type, flags, root->kf_root); | |
1590 | if (IS_ERR(dentry)) | |
776f02fa | 1591 | cgroup_put(&root->top_cgroup); |
2bd59d48 TH |
1592 | return dentry; |
1593 | } | |
1594 | ||
1595 | static void cgroup_kill_sb(struct super_block *sb) | |
1596 | { | |
1597 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
1598 | struct cgroupfs_root *root = cgroup_root_from_kf(kf_root); | |
1599 | ||
776f02fa | 1600 | cgroup_put(&root->top_cgroup); |
2bd59d48 | 1601 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
1602 | } |
1603 | ||
ddbcc7e8 PM |
1604 | static struct file_system_type cgroup_fs_type = { |
1605 | .name = "cgroup", | |
f7e83571 | 1606 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1607 | .kill_sb = cgroup_kill_sb, |
1608 | }; | |
1609 | ||
676db4af GK |
1610 | static struct kobject *cgroup_kobj; |
1611 | ||
857a2beb | 1612 | /** |
913ffdb5 | 1613 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 1614 | * @task: target task |
857a2beb TH |
1615 | * @buf: the buffer to write the path into |
1616 | * @buflen: the length of the buffer | |
1617 | * | |
913ffdb5 TH |
1618 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
1619 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
1620 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
1621 | * cgroup controller callbacks. | |
1622 | * | |
e61734c5 | 1623 | * Return value is the same as kernfs_path(). |
857a2beb | 1624 | */ |
e61734c5 | 1625 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb TH |
1626 | { |
1627 | struct cgroupfs_root *root; | |
913ffdb5 | 1628 | struct cgroup *cgrp; |
e61734c5 TH |
1629 | int hierarchy_id = 1; |
1630 | char *path = NULL; | |
857a2beb TH |
1631 | |
1632 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 1633 | down_read(&css_set_rwsem); |
857a2beb | 1634 | |
913ffdb5 TH |
1635 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
1636 | ||
857a2beb TH |
1637 | if (root) { |
1638 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 1639 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
1640 | } else { |
1641 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
1642 | if (strlcpy(buf, "/", buflen) < buflen) |
1643 | path = buf; | |
857a2beb TH |
1644 | } |
1645 | ||
96d365e0 | 1646 | up_read(&css_set_rwsem); |
857a2beb | 1647 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 1648 | return path; |
857a2beb | 1649 | } |
913ffdb5 | 1650 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 1651 | |
b3dc094e | 1652 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 1653 | struct cgroup_taskset { |
b3dc094e TH |
1654 | /* the src and dst cset list running through cset->mg_node */ |
1655 | struct list_head src_csets; | |
1656 | struct list_head dst_csets; | |
1657 | ||
1658 | /* | |
1659 | * Fields for cgroup_taskset_*() iteration. | |
1660 | * | |
1661 | * Before migration is committed, the target migration tasks are on | |
1662 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
1663 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
1664 | * or ->dst_csets depending on whether migration is committed. | |
1665 | * | |
1666 | * ->cur_csets and ->cur_task point to the current task position | |
1667 | * during iteration. | |
1668 | */ | |
1669 | struct list_head *csets; | |
1670 | struct css_set *cur_cset; | |
1671 | struct task_struct *cur_task; | |
2f7ee569 TH |
1672 | }; |
1673 | ||
1674 | /** | |
1675 | * cgroup_taskset_first - reset taskset and return the first task | |
1676 | * @tset: taskset of interest | |
1677 | * | |
1678 | * @tset iteration is initialized and the first task is returned. | |
1679 | */ | |
1680 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1681 | { | |
b3dc094e TH |
1682 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
1683 | tset->cur_task = NULL; | |
1684 | ||
1685 | return cgroup_taskset_next(tset); | |
2f7ee569 | 1686 | } |
2f7ee569 TH |
1687 | |
1688 | /** | |
1689 | * cgroup_taskset_next - iterate to the next task in taskset | |
1690 | * @tset: taskset of interest | |
1691 | * | |
1692 | * Return the next task in @tset. Iteration must have been initialized | |
1693 | * with cgroup_taskset_first(). | |
1694 | */ | |
1695 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1696 | { | |
b3dc094e TH |
1697 | struct css_set *cset = tset->cur_cset; |
1698 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 1699 | |
b3dc094e TH |
1700 | while (&cset->mg_node != tset->csets) { |
1701 | if (!task) | |
1702 | task = list_first_entry(&cset->mg_tasks, | |
1703 | struct task_struct, cg_list); | |
1704 | else | |
1705 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 1706 | |
b3dc094e TH |
1707 | if (&task->cg_list != &cset->mg_tasks) { |
1708 | tset->cur_cset = cset; | |
1709 | tset->cur_task = task; | |
1710 | return task; | |
1711 | } | |
1712 | ||
1713 | cset = list_next_entry(cset, mg_node); | |
1714 | task = NULL; | |
1715 | } | |
1716 | ||
1717 | return NULL; | |
2f7ee569 | 1718 | } |
2f7ee569 | 1719 | |
cb0f1fe9 | 1720 | /** |
74a1166d | 1721 | * cgroup_task_migrate - move a task from one cgroup to another. |
cb0f1fe9 TH |
1722 | * @old_cgrp; the cgroup @tsk is being migrated from |
1723 | * @tsk: the task being migrated | |
1724 | * @new_cset: the new css_set @tsk is being attached to | |
74a1166d | 1725 | * |
cb0f1fe9 | 1726 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. |
74a1166d | 1727 | */ |
5abb8855 TH |
1728 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
1729 | struct task_struct *tsk, | |
1730 | struct css_set *new_cset) | |
74a1166d | 1731 | { |
5abb8855 | 1732 | struct css_set *old_cset; |
74a1166d | 1733 | |
cb0f1fe9 TH |
1734 | lockdep_assert_held(&cgroup_mutex); |
1735 | lockdep_assert_held(&css_set_rwsem); | |
1736 | ||
74a1166d | 1737 | /* |
026085ef MSB |
1738 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1739 | * setting such that we can't race against cgroup_exit() changing the | |
1740 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1741 | */ |
c84cdf75 | 1742 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 1743 | old_cset = task_css_set(tsk); |
74a1166d | 1744 | |
b3dc094e TH |
1745 | get_css_set(new_cset); |
1746 | ||
74a1166d | 1747 | task_lock(tsk); |
5abb8855 | 1748 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d BB |
1749 | task_unlock(tsk); |
1750 | ||
b3dc094e | 1751 | list_move(&tsk->cg_list, &new_cset->mg_tasks); |
74a1166d BB |
1752 | |
1753 | /* | |
5abb8855 TH |
1754 | * We just gained a reference on old_cset by taking it from the |
1755 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
1756 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 1757 | */ |
5abb8855 | 1758 | set_bit(CGRP_RELEASABLE, &old_cgrp->flags); |
cb0f1fe9 | 1759 | put_css_set_locked(old_cset, false); |
74a1166d BB |
1760 | } |
1761 | ||
a043e3b2 | 1762 | /** |
1958d2d5 TH |
1763 | * cgroup_migrate_finish - cleanup after attach |
1764 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 1765 | * |
1958d2d5 TH |
1766 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
1767 | * those functions for details. | |
74a1166d | 1768 | */ |
1958d2d5 TH |
1769 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
1770 | { | |
1771 | struct css_set *cset, *tmp_cset; | |
1772 | ||
1773 | lockdep_assert_held(&cgroup_mutex); | |
1774 | ||
1775 | down_write(&css_set_rwsem); | |
1776 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { | |
1777 | cset->mg_src_cgrp = NULL; | |
1778 | cset->mg_dst_cset = NULL; | |
1779 | list_del_init(&cset->mg_preload_node); | |
1780 | put_css_set_locked(cset, false); | |
1781 | } | |
1782 | up_write(&css_set_rwsem); | |
1783 | } | |
1784 | ||
1785 | /** | |
1786 | * cgroup_migrate_add_src - add a migration source css_set | |
1787 | * @src_cset: the source css_set to add | |
1788 | * @dst_cgrp: the destination cgroup | |
1789 | * @preloaded_csets: list of preloaded css_sets | |
1790 | * | |
1791 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
1792 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
1793 | * up by cgroup_migrate_finish(). | |
1794 | * | |
1795 | * This function may be called without holding threadgroup_lock even if the | |
1796 | * target is a process. Threads may be created and destroyed but as long | |
1797 | * as cgroup_mutex is not dropped, no new css_set can be put into play and | |
1798 | * the preloaded css_sets are guaranteed to cover all migrations. | |
1799 | */ | |
1800 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
1801 | struct cgroup *dst_cgrp, | |
1802 | struct list_head *preloaded_csets) | |
1803 | { | |
1804 | struct cgroup *src_cgrp; | |
1805 | ||
1806 | lockdep_assert_held(&cgroup_mutex); | |
1807 | lockdep_assert_held(&css_set_rwsem); | |
1808 | ||
1809 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
1810 | ||
1811 | /* nothing to do if this cset already belongs to the cgroup */ | |
1812 | if (src_cgrp == dst_cgrp) | |
1813 | return; | |
1814 | ||
1815 | if (!list_empty(&src_cset->mg_preload_node)) | |
1816 | return; | |
1817 | ||
1818 | WARN_ON(src_cset->mg_src_cgrp); | |
1819 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
1820 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
1821 | ||
1822 | src_cset->mg_src_cgrp = src_cgrp; | |
1823 | get_css_set(src_cset); | |
1824 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
1825 | } | |
1826 | ||
1827 | /** | |
1828 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
1829 | * @dst_cgrp: the destination cgroup | |
1830 | * @preloaded_csets: list of preloaded source css_sets | |
1831 | * | |
1832 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
1833 | * have been preloaded to @preloaded_csets. This function looks up and | |
1834 | * pins all destination css_sets, links each to its source, and put them on | |
1835 | * @preloaded_csets. | |
1836 | * | |
1837 | * This function must be called after cgroup_migrate_add_src() has been | |
1838 | * called on each migration source css_set. After migration is performed | |
1839 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
1840 | * @preloaded_csets. | |
1841 | */ | |
1842 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
1843 | struct list_head *preloaded_csets) | |
1844 | { | |
1845 | LIST_HEAD(csets); | |
1846 | struct css_set *src_cset; | |
1847 | ||
1848 | lockdep_assert_held(&cgroup_mutex); | |
1849 | ||
1850 | /* look up the dst cset for each src cset and link it to src */ | |
1851 | list_for_each_entry(src_cset, preloaded_csets, mg_preload_node) { | |
1852 | struct css_set *dst_cset; | |
1853 | ||
1854 | dst_cset = find_css_set(src_cset, dst_cgrp); | |
1855 | if (!dst_cset) | |
1856 | goto err; | |
1857 | ||
1858 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
1859 | src_cset->mg_dst_cset = dst_cset; | |
1860 | ||
1861 | if (list_empty(&dst_cset->mg_preload_node)) | |
1862 | list_add(&dst_cset->mg_preload_node, &csets); | |
1863 | else | |
1864 | put_css_set(dst_cset, false); | |
1865 | } | |
1866 | ||
1867 | list_splice(&csets, preloaded_csets); | |
1868 | return 0; | |
1869 | err: | |
1870 | cgroup_migrate_finish(&csets); | |
1871 | return -ENOMEM; | |
1872 | } | |
1873 | ||
1874 | /** | |
1875 | * cgroup_migrate - migrate a process or task to a cgroup | |
1876 | * @cgrp: the destination cgroup | |
1877 | * @leader: the leader of the process or the task to migrate | |
1878 | * @threadgroup: whether @leader points to the whole process or a single task | |
1879 | * | |
1880 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1881 | * process, the caller must be holding threadgroup_lock of @leader. The | |
1882 | * caller is also responsible for invoking cgroup_migrate_add_src() and | |
1883 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
1884 | * function and following up with cgroup_migrate_finish(). | |
1885 | * | |
1886 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
1887 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
1888 | * failure, when migrating multiple targets, the success or failure can be | |
1889 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
1890 | * actually starting migrating. | |
1891 | */ | |
1892 | static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader, | |
1893 | bool threadgroup) | |
74a1166d | 1894 | { |
b3dc094e TH |
1895 | struct cgroup_taskset tset = { |
1896 | .src_csets = LIST_HEAD_INIT(tset.src_csets), | |
1897 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), | |
1898 | .csets = &tset.src_csets, | |
1899 | }; | |
1c6727af | 1900 | struct cgroup_subsys_state *css, *failed_css = NULL; |
b3dc094e TH |
1901 | struct css_set *cset, *tmp_cset; |
1902 | struct task_struct *task, *tmp_task; | |
1903 | int i, ret; | |
74a1166d | 1904 | |
fb5d2b4c MSB |
1905 | /* |
1906 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
1907 | * already PF_EXITING could be freed from underneath us unless we | |
1908 | * take an rcu_read_lock. | |
1909 | */ | |
b3dc094e | 1910 | down_write(&css_set_rwsem); |
fb5d2b4c | 1911 | rcu_read_lock(); |
9db8de37 | 1912 | task = leader; |
74a1166d | 1913 | do { |
9db8de37 TH |
1914 | /* @task either already exited or can't exit until the end */ |
1915 | if (task->flags & PF_EXITING) | |
ea84753c | 1916 | goto next; |
cd3d0952 | 1917 | |
eaf797ab TH |
1918 | /* leave @task alone if post_fork() hasn't linked it yet */ |
1919 | if (list_empty(&task->cg_list)) | |
1920 | goto next; | |
1921 | ||
b3dc094e | 1922 | cset = task_css_set(task); |
1958d2d5 | 1923 | if (!cset->mg_src_cgrp) |
ea84753c | 1924 | goto next; |
b3dc094e | 1925 | |
b3dc094e | 1926 | list_move(&task->cg_list, &cset->mg_tasks); |
1958d2d5 TH |
1927 | list_move(&cset->mg_node, &tset.src_csets); |
1928 | list_move(&cset->mg_dst_cset->mg_node, &tset.dst_csets); | |
ea84753c | 1929 | next: |
081aa458 LZ |
1930 | if (!threadgroup) |
1931 | break; | |
9db8de37 | 1932 | } while_each_thread(leader, task); |
fb5d2b4c | 1933 | rcu_read_unlock(); |
b3dc094e | 1934 | up_write(&css_set_rwsem); |
74a1166d | 1935 | |
134d3373 | 1936 | /* methods shouldn't be called if no task is actually migrating */ |
b3dc094e TH |
1937 | if (list_empty(&tset.src_csets)) |
1938 | return 0; | |
134d3373 | 1939 | |
1958d2d5 | 1940 | /* check that we can legitimately attach to the cgroup */ |
1c6727af TH |
1941 | for_each_css(css, i, cgrp) { |
1942 | if (css->ss->can_attach) { | |
9db8de37 TH |
1943 | ret = css->ss->can_attach(css, &tset); |
1944 | if (ret) { | |
1c6727af | 1945 | failed_css = css; |
74a1166d BB |
1946 | goto out_cancel_attach; |
1947 | } | |
1948 | } | |
74a1166d BB |
1949 | } |
1950 | ||
1951 | /* | |
1958d2d5 TH |
1952 | * Now that we're guaranteed success, proceed to move all tasks to |
1953 | * the new cgroup. There are no failure cases after here, so this | |
1954 | * is the commit point. | |
74a1166d | 1955 | */ |
cb0f1fe9 | 1956 | down_write(&css_set_rwsem); |
b3dc094e TH |
1957 | list_for_each_entry(cset, &tset.src_csets, mg_node) { |
1958 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) | |
1959 | cgroup_task_migrate(cset->mg_src_cgrp, task, | |
1960 | cset->mg_dst_cset); | |
74a1166d | 1961 | } |
cb0f1fe9 | 1962 | up_write(&css_set_rwsem); |
b3dc094e | 1963 | |
74a1166d | 1964 | /* |
1958d2d5 TH |
1965 | * Migration is committed, all target tasks are now on dst_csets. |
1966 | * Nothing is sensitive to fork() after this point. Notify | |
1967 | * controllers that migration is complete. | |
74a1166d | 1968 | */ |
1958d2d5 TH |
1969 | tset.csets = &tset.dst_csets; |
1970 | ||
1c6727af TH |
1971 | for_each_css(css, i, cgrp) |
1972 | if (css->ss->attach) | |
1973 | css->ss->attach(css, &tset); | |
74a1166d | 1974 | |
9db8de37 | 1975 | ret = 0; |
b3dc094e TH |
1976 | goto out_release_tset; |
1977 | ||
74a1166d | 1978 | out_cancel_attach: |
b3dc094e TH |
1979 | for_each_css(css, i, cgrp) { |
1980 | if (css == failed_css) | |
1981 | break; | |
1982 | if (css->ss->cancel_attach) | |
1983 | css->ss->cancel_attach(css, &tset); | |
74a1166d | 1984 | } |
b3dc094e TH |
1985 | out_release_tset: |
1986 | down_write(&css_set_rwsem); | |
1987 | list_splice_init(&tset.dst_csets, &tset.src_csets); | |
1988 | list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) { | |
1989 | list_splice_init(&cset->mg_tasks, &cset->tasks); | |
b3dc094e | 1990 | list_del_init(&cset->mg_node); |
b3dc094e TH |
1991 | } |
1992 | up_write(&css_set_rwsem); | |
9db8de37 | 1993 | return ret; |
74a1166d BB |
1994 | } |
1995 | ||
1958d2d5 TH |
1996 | /** |
1997 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
1998 | * @dst_cgrp: the cgroup to attach to | |
1999 | * @leader: the task or the leader of the threadgroup to be attached | |
2000 | * @threadgroup: attach the whole threadgroup? | |
2001 | * | |
2002 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take | |
2003 | * task_lock of @tsk or each thread in the threadgroup individually in turn. | |
2004 | */ | |
2005 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2006 | struct task_struct *leader, bool threadgroup) | |
2007 | { | |
2008 | LIST_HEAD(preloaded_csets); | |
2009 | struct task_struct *task; | |
2010 | int ret; | |
2011 | ||
2012 | /* look up all src csets */ | |
2013 | down_read(&css_set_rwsem); | |
2014 | rcu_read_lock(); | |
2015 | task = leader; | |
2016 | do { | |
2017 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2018 | &preloaded_csets); | |
2019 | if (!threadgroup) | |
2020 | break; | |
2021 | } while_each_thread(leader, task); | |
2022 | rcu_read_unlock(); | |
2023 | up_read(&css_set_rwsem); | |
2024 | ||
2025 | /* prepare dst csets and commit */ | |
2026 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2027 | if (!ret) | |
2028 | ret = cgroup_migrate(dst_cgrp, leader, threadgroup); | |
2029 | ||
2030 | cgroup_migrate_finish(&preloaded_csets); | |
2031 | return ret; | |
2032 | } | |
2033 | ||
74a1166d BB |
2034 | /* |
2035 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 TH |
2036 | * function to attach either it or all tasks in its threadgroup. Will lock |
2037 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
bbcb81d0 | 2038 | */ |
74a1166d | 2039 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2040 | { |
bbcb81d0 | 2041 | struct task_struct *tsk; |
c69e8d9c | 2042 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2043 | int ret; |
2044 | ||
74a1166d BB |
2045 | if (!cgroup_lock_live_group(cgrp)) |
2046 | return -ENODEV; | |
2047 | ||
b78949eb MSB |
2048 | retry_find_task: |
2049 | rcu_read_lock(); | |
bbcb81d0 | 2050 | if (pid) { |
73507f33 | 2051 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2052 | if (!tsk) { |
2053 | rcu_read_unlock(); | |
dd4b0a46 | 2054 | ret = -ESRCH; |
b78949eb | 2055 | goto out_unlock_cgroup; |
bbcb81d0 | 2056 | } |
74a1166d BB |
2057 | /* |
2058 | * even if we're attaching all tasks in the thread group, we | |
2059 | * only need to check permissions on one of them. | |
2060 | */ | |
c69e8d9c | 2061 | tcred = __task_cred(tsk); |
14a590c3 EB |
2062 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
2063 | !uid_eq(cred->euid, tcred->uid) && | |
2064 | !uid_eq(cred->euid, tcred->suid)) { | |
c69e8d9c | 2065 | rcu_read_unlock(); |
b78949eb MSB |
2066 | ret = -EACCES; |
2067 | goto out_unlock_cgroup; | |
bbcb81d0 | 2068 | } |
b78949eb MSB |
2069 | } else |
2070 | tsk = current; | |
cd3d0952 TH |
2071 | |
2072 | if (threadgroup) | |
b78949eb | 2073 | tsk = tsk->group_leader; |
c4c27fbd MG |
2074 | |
2075 | /* | |
14a40ffc | 2076 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2077 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2078 | * with no rt_runtime allocated. Just say no. | |
2079 | */ | |
14a40ffc | 2080 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd MG |
2081 | ret = -EINVAL; |
2082 | rcu_read_unlock(); | |
2083 | goto out_unlock_cgroup; | |
2084 | } | |
2085 | ||
b78949eb MSB |
2086 | get_task_struct(tsk); |
2087 | rcu_read_unlock(); | |
2088 | ||
2089 | threadgroup_lock(tsk); | |
2090 | if (threadgroup) { | |
2091 | if (!thread_group_leader(tsk)) { | |
2092 | /* | |
2093 | * a race with de_thread from another thread's exec() | |
2094 | * may strip us of our leadership, if this happens, | |
2095 | * there is no choice but to throw this task away and | |
2096 | * try again; this is | |
2097 | * "double-double-toil-and-trouble-check locking". | |
2098 | */ | |
2099 | threadgroup_unlock(tsk); | |
2100 | put_task_struct(tsk); | |
2101 | goto retry_find_task; | |
2102 | } | |
081aa458 LZ |
2103 | } |
2104 | ||
2105 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
2106 | ||
cd3d0952 TH |
2107 | threadgroup_unlock(tsk); |
2108 | ||
bbcb81d0 | 2109 | put_task_struct(tsk); |
b78949eb | 2110 | out_unlock_cgroup: |
47cfcd09 | 2111 | mutex_unlock(&cgroup_mutex); |
bbcb81d0 PM |
2112 | return ret; |
2113 | } | |
2114 | ||
7ae1bad9 TH |
2115 | /** |
2116 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2117 | * @from: attach to all cgroups of a given task | |
2118 | * @tsk: the task to be attached | |
2119 | */ | |
2120 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2121 | { | |
2122 | struct cgroupfs_root *root; | |
2123 | int retval = 0; | |
2124 | ||
47cfcd09 | 2125 | mutex_lock(&cgroup_mutex); |
7ae1bad9 | 2126 | for_each_active_root(root) { |
96d365e0 TH |
2127 | struct cgroup *from_cgrp; |
2128 | ||
2129 | down_read(&css_set_rwsem); | |
2130 | from_cgrp = task_cgroup_from_root(from, root); | |
2131 | up_read(&css_set_rwsem); | |
7ae1bad9 | 2132 | |
6f4b7e63 | 2133 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2134 | if (retval) |
2135 | break; | |
2136 | } | |
47cfcd09 | 2137 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2138 | |
2139 | return retval; | |
2140 | } | |
2141 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2142 | ||
182446d0 TH |
2143 | static int cgroup_tasks_write(struct cgroup_subsys_state *css, |
2144 | struct cftype *cft, u64 pid) | |
74a1166d | 2145 | { |
182446d0 | 2146 | return attach_task_by_pid(css->cgroup, pid, false); |
74a1166d BB |
2147 | } |
2148 | ||
182446d0 TH |
2149 | static int cgroup_procs_write(struct cgroup_subsys_state *css, |
2150 | struct cftype *cft, u64 tgid) | |
af351026 | 2151 | { |
182446d0 | 2152 | return attach_task_by_pid(css->cgroup, tgid, true); |
af351026 PM |
2153 | } |
2154 | ||
182446d0 TH |
2155 | static int cgroup_release_agent_write(struct cgroup_subsys_state *css, |
2156 | struct cftype *cft, const char *buffer) | |
e788e066 | 2157 | { |
5f469907 TH |
2158 | struct cgroupfs_root *root = css->cgroup->root; |
2159 | ||
2160 | BUILD_BUG_ON(sizeof(root->release_agent_path) < PATH_MAX); | |
182446d0 | 2161 | if (!cgroup_lock_live_group(css->cgroup)) |
e788e066 | 2162 | return -ENODEV; |
69e943b7 | 2163 | spin_lock(&release_agent_path_lock); |
5f469907 TH |
2164 | strlcpy(root->release_agent_path, buffer, |
2165 | sizeof(root->release_agent_path)); | |
69e943b7 | 2166 | spin_unlock(&release_agent_path_lock); |
47cfcd09 | 2167 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2168 | return 0; |
2169 | } | |
2170 | ||
2da8ca82 | 2171 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2172 | { |
2da8ca82 | 2173 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2174 | |
e788e066 PM |
2175 | if (!cgroup_lock_live_group(cgrp)) |
2176 | return -ENODEV; | |
2177 | seq_puts(seq, cgrp->root->release_agent_path); | |
2178 | seq_putc(seq, '\n'); | |
47cfcd09 | 2179 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2180 | return 0; |
2181 | } | |
2182 | ||
2da8ca82 | 2183 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2184 | { |
2da8ca82 TH |
2185 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2186 | ||
2187 | seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); | |
e788e066 PM |
2188 | return 0; |
2189 | } | |
2190 | ||
2bd59d48 TH |
2191 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
2192 | size_t nbytes, loff_t off) | |
355e0c48 | 2193 | { |
2bd59d48 TH |
2194 | struct cgroup *cgrp = of->kn->parent->priv; |
2195 | struct cftype *cft = of->kn->priv; | |
2196 | struct cgroup_subsys_state *css; | |
a742c59d | 2197 | int ret; |
355e0c48 | 2198 | |
2bd59d48 TH |
2199 | /* |
2200 | * kernfs guarantees that a file isn't deleted with operations in | |
2201 | * flight, which means that the matching css is and stays alive and | |
2202 | * doesn't need to be pinned. The RCU locking is not necessary | |
2203 | * either. It's just for the convenience of using cgroup_css(). | |
2204 | */ | |
2205 | rcu_read_lock(); | |
2206 | css = cgroup_css(cgrp, cft->ss); | |
2207 | rcu_read_unlock(); | |
a742c59d TH |
2208 | |
2209 | if (cft->write_string) { | |
2210 | ret = cft->write_string(css, cft, strstrip(buf)); | |
2211 | } else if (cft->write_u64) { | |
2212 | unsigned long long v; | |
2213 | ret = kstrtoull(buf, 0, &v); | |
2214 | if (!ret) | |
2215 | ret = cft->write_u64(css, cft, v); | |
2216 | } else if (cft->write_s64) { | |
2217 | long long v; | |
2218 | ret = kstrtoll(buf, 0, &v); | |
2219 | if (!ret) | |
2220 | ret = cft->write_s64(css, cft, v); | |
2221 | } else if (cft->trigger) { | |
2222 | ret = cft->trigger(css, (unsigned int)cft->private); | |
e73d2c61 | 2223 | } else { |
a742c59d | 2224 | ret = -EINVAL; |
e73d2c61 | 2225 | } |
2bd59d48 | 2226 | |
a742c59d | 2227 | return ret ?: nbytes; |
355e0c48 PM |
2228 | } |
2229 | ||
6612f05b | 2230 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 2231 | { |
2bd59d48 | 2232 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
2233 | } |
2234 | ||
6612f05b | 2235 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 2236 | { |
2bd59d48 | 2237 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
2238 | } |
2239 | ||
6612f05b | 2240 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 2241 | { |
2bd59d48 | 2242 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
2243 | } |
2244 | ||
91796569 | 2245 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 2246 | { |
7da11279 TH |
2247 | struct cftype *cft = seq_cft(m); |
2248 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 2249 | |
2da8ca82 TH |
2250 | if (cft->seq_show) |
2251 | return cft->seq_show(m, arg); | |
e73d2c61 | 2252 | |
f4c753b7 | 2253 | if (cft->read_u64) |
896f5199 TH |
2254 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
2255 | else if (cft->read_s64) | |
2256 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
2257 | else | |
2258 | return -EINVAL; | |
2259 | return 0; | |
91796569 PM |
2260 | } |
2261 | ||
2bd59d48 TH |
2262 | static struct kernfs_ops cgroup_kf_single_ops = { |
2263 | .atomic_write_len = PAGE_SIZE, | |
2264 | .write = cgroup_file_write, | |
2265 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
2266 | }; |
2267 | ||
2bd59d48 TH |
2268 | static struct kernfs_ops cgroup_kf_ops = { |
2269 | .atomic_write_len = PAGE_SIZE, | |
2270 | .write = cgroup_file_write, | |
2271 | .seq_start = cgroup_seqfile_start, | |
2272 | .seq_next = cgroup_seqfile_next, | |
2273 | .seq_stop = cgroup_seqfile_stop, | |
2274 | .seq_show = cgroup_seqfile_show, | |
2275 | }; | |
ddbcc7e8 PM |
2276 | |
2277 | /* | |
2278 | * cgroup_rename - Only allow simple rename of directories in place. | |
2279 | */ | |
2bd59d48 TH |
2280 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
2281 | const char *new_name_str) | |
ddbcc7e8 | 2282 | { |
2bd59d48 | 2283 | struct cgroup *cgrp = kn->priv; |
2bd59d48 | 2284 | int ret; |
65dff759 | 2285 | |
2bd59d48 | 2286 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 2287 | return -ENOTDIR; |
2bd59d48 | 2288 | if (kn->parent != new_parent) |
ddbcc7e8 | 2289 | return -EIO; |
65dff759 | 2290 | |
6db8e85c TH |
2291 | /* |
2292 | * This isn't a proper migration and its usefulness is very | |
2293 | * limited. Disallow if sane_behavior. | |
2294 | */ | |
2295 | if (cgroup_sane_behavior(cgrp)) | |
2296 | return -EPERM; | |
2297 | ||
2bd59d48 TH |
2298 | mutex_lock(&cgroup_tree_mutex); |
2299 | mutex_lock(&cgroup_mutex); | |
2300 | ||
2301 | ret = kernfs_rename(kn, new_parent, new_name_str); | |
65dff759 | 2302 | |
2bd59d48 TH |
2303 | mutex_unlock(&cgroup_mutex); |
2304 | mutex_unlock(&cgroup_tree_mutex); | |
2bd59d48 | 2305 | return ret; |
ddbcc7e8 PM |
2306 | } |
2307 | ||
2bb566cb | 2308 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) |
ddbcc7e8 | 2309 | { |
8d7e6fb0 | 2310 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
2311 | struct kernfs_node *kn; |
2312 | struct lock_class_key *key = NULL; | |
05ef1d7c | 2313 | |
2bd59d48 TH |
2314 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
2315 | key = &cft->lockdep_key; | |
2316 | #endif | |
2317 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
2318 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
2319 | NULL, false, key); | |
430af8ad | 2320 | return PTR_ERR_OR_ZERO(kn); |
ddbcc7e8 PM |
2321 | } |
2322 | ||
b1f28d31 TH |
2323 | /** |
2324 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
2325 | * @cgrp: the target cgroup | |
b1f28d31 TH |
2326 | * @cfts: array of cftypes to be added |
2327 | * @is_add: whether to add or remove | |
2328 | * | |
2329 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
2bb566cb TH |
2330 | * For removals, this function never fails. If addition fails, this |
2331 | * function doesn't remove files already added. The caller is responsible | |
2332 | * for cleaning up. | |
b1f28d31 | 2333 | */ |
2bb566cb TH |
2334 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
2335 | bool is_add) | |
ddbcc7e8 | 2336 | { |
03b1cde6 | 2337 | struct cftype *cft; |
b1f28d31 TH |
2338 | int ret; |
2339 | ||
ace2bee8 | 2340 | lockdep_assert_held(&cgroup_tree_mutex); |
db0416b6 TH |
2341 | |
2342 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 2343 | /* does cft->flags tell us to skip this file on @cgrp? */ |
873fe09e TH |
2344 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) |
2345 | continue; | |
f33fddc2 G |
2346 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
2347 | continue; | |
2348 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2349 | continue; | |
2350 | ||
2739d3cc | 2351 | if (is_add) { |
2bb566cb | 2352 | ret = cgroup_add_file(cgrp, cft); |
b1f28d31 | 2353 | if (ret) { |
2739d3cc | 2354 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", |
b1f28d31 TH |
2355 | cft->name, ret); |
2356 | return ret; | |
2357 | } | |
2739d3cc LZ |
2358 | } else { |
2359 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2360 | } |
ddbcc7e8 | 2361 | } |
b1f28d31 | 2362 | return 0; |
ddbcc7e8 PM |
2363 | } |
2364 | ||
21a2d343 | 2365 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
2366 | { |
2367 | LIST_HEAD(pending); | |
2bb566cb | 2368 | struct cgroup_subsys *ss = cfts[0].ss; |
492eb21b | 2369 | struct cgroup *root = &ss->root->top_cgroup; |
492eb21b | 2370 | struct cgroup_subsys_state *css; |
9ccece80 | 2371 | int ret = 0; |
8e3f6541 | 2372 | |
21a2d343 | 2373 | lockdep_assert_held(&cgroup_tree_mutex); |
4ac06017 | 2374 | |
21a2d343 TH |
2375 | /* don't bother if @ss isn't attached */ |
2376 | if (ss->root == &cgroup_dummy_root) | |
9ccece80 | 2377 | return 0; |
e8c82d20 | 2378 | |
e8c82d20 | 2379 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 2380 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
2381 | struct cgroup *cgrp = css->cgroup; |
2382 | ||
e8c82d20 LZ |
2383 | if (cgroup_is_dead(cgrp)) |
2384 | continue; | |
2385 | ||
21a2d343 | 2386 | ret = cgroup_addrm_files(cgrp, cfts, is_add); |
9ccece80 TH |
2387 | if (ret) |
2388 | break; | |
8e3f6541 | 2389 | } |
21a2d343 TH |
2390 | |
2391 | if (is_add && !ret) | |
2392 | kernfs_activate(root->kn); | |
9ccece80 | 2393 | return ret; |
8e3f6541 TH |
2394 | } |
2395 | ||
2da440a2 TH |
2396 | static void cgroup_exit_cftypes(struct cftype *cfts) |
2397 | { | |
2398 | struct cftype *cft; | |
2399 | ||
2bd59d48 TH |
2400 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
2401 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
2402 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
2403 | kfree(cft->kf_ops); | |
2404 | cft->kf_ops = NULL; | |
2da440a2 | 2405 | cft->ss = NULL; |
2bd59d48 | 2406 | } |
2da440a2 TH |
2407 | } |
2408 | ||
2bd59d48 | 2409 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
2410 | { |
2411 | struct cftype *cft; | |
2412 | ||
2bd59d48 TH |
2413 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
2414 | struct kernfs_ops *kf_ops; | |
2415 | ||
0adb0704 TH |
2416 | WARN_ON(cft->ss || cft->kf_ops); |
2417 | ||
2bd59d48 TH |
2418 | if (cft->seq_start) |
2419 | kf_ops = &cgroup_kf_ops; | |
2420 | else | |
2421 | kf_ops = &cgroup_kf_single_ops; | |
2422 | ||
2423 | /* | |
2424 | * Ugh... if @cft wants a custom max_write_len, we need to | |
2425 | * make a copy of kf_ops to set its atomic_write_len. | |
2426 | */ | |
2427 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
2428 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
2429 | if (!kf_ops) { | |
2430 | cgroup_exit_cftypes(cfts); | |
2431 | return -ENOMEM; | |
2432 | } | |
2433 | kf_ops->atomic_write_len = cft->max_write_len; | |
2434 | } | |
2435 | ||
2436 | cft->kf_ops = kf_ops; | |
2da440a2 | 2437 | cft->ss = ss; |
2bd59d48 TH |
2438 | } |
2439 | ||
2440 | return 0; | |
2da440a2 TH |
2441 | } |
2442 | ||
21a2d343 TH |
2443 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
2444 | { | |
2445 | lockdep_assert_held(&cgroup_tree_mutex); | |
2446 | ||
2447 | if (!cfts || !cfts[0].ss) | |
2448 | return -ENOENT; | |
2449 | ||
2450 | list_del(&cfts->node); | |
2451 | cgroup_apply_cftypes(cfts, false); | |
2452 | cgroup_exit_cftypes(cfts); | |
2453 | return 0; | |
2454 | } | |
2455 | ||
80b13586 TH |
2456 | /** |
2457 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
2458 | * @cfts: zero-length name terminated array of cftypes | |
2459 | * | |
2460 | * Unregister @cfts. Files described by @cfts are removed from all | |
2461 | * existing cgroups and all future cgroups won't have them either. This | |
2462 | * function can be called anytime whether @cfts' subsys is attached or not. | |
2463 | * | |
2464 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2465 | * registered. | |
2466 | */ | |
2467 | int cgroup_rm_cftypes(struct cftype *cfts) | |
2468 | { | |
21a2d343 | 2469 | int ret; |
80b13586 | 2470 | |
21a2d343 TH |
2471 | mutex_lock(&cgroup_tree_mutex); |
2472 | ret = cgroup_rm_cftypes_locked(cfts); | |
2473 | mutex_unlock(&cgroup_tree_mutex); | |
2474 | return ret; | |
80b13586 TH |
2475 | } |
2476 | ||
8e3f6541 TH |
2477 | /** |
2478 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2479 | * @ss: target cgroup subsystem | |
2480 | * @cfts: zero-length name terminated array of cftypes | |
2481 | * | |
2482 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2483 | * existing cgroups to which @ss is attached and all future cgroups will | |
2484 | * have them too. This function can be called anytime whether @ss is | |
2485 | * attached or not. | |
2486 | * | |
2487 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2488 | * function currently returns 0 as long as @cfts registration is successful | |
2489 | * even if some file creation attempts on existing cgroups fail. | |
2490 | */ | |
03b1cde6 | 2491 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 2492 | { |
9ccece80 | 2493 | int ret; |
8e3f6541 | 2494 | |
dc5736ed LZ |
2495 | if (!cfts || cfts[0].name[0] == '\0') |
2496 | return 0; | |
2497 | ||
2bd59d48 TH |
2498 | ret = cgroup_init_cftypes(ss, cfts); |
2499 | if (ret) | |
2500 | return ret; | |
2bb566cb | 2501 | |
21a2d343 TH |
2502 | mutex_lock(&cgroup_tree_mutex); |
2503 | ||
0adb0704 | 2504 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 2505 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 2506 | if (ret) |
21a2d343 TH |
2507 | cgroup_rm_cftypes_locked(cfts); |
2508 | ||
2509 | mutex_unlock(&cgroup_tree_mutex); | |
9ccece80 | 2510 | return ret; |
8e3f6541 | 2511 | } |
8e3f6541 | 2512 | |
a043e3b2 LZ |
2513 | /** |
2514 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2515 | * @cgrp: the cgroup in question | |
2516 | * | |
2517 | * Return the number of tasks in the cgroup. | |
2518 | */ | |
07bc356e | 2519 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2520 | { |
2521 | int count = 0; | |
69d0206c | 2522 | struct cgrp_cset_link *link; |
817929ec | 2523 | |
96d365e0 | 2524 | down_read(&css_set_rwsem); |
69d0206c TH |
2525 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
2526 | count += atomic_read(&link->cset->refcount); | |
96d365e0 | 2527 | up_read(&css_set_rwsem); |
bbcb81d0 PM |
2528 | return count; |
2529 | } | |
2530 | ||
53fa5261 | 2531 | /** |
492eb21b TH |
2532 | * css_next_child - find the next child of a given css |
2533 | * @pos_css: the current position (%NULL to initiate traversal) | |
2534 | * @parent_css: css whose children to walk | |
53fa5261 | 2535 | * |
492eb21b | 2536 | * This function returns the next child of @parent_css and should be called |
87fb54f1 TH |
2537 | * under either cgroup_mutex or RCU read lock. The only requirement is |
2538 | * that @parent_css and @pos_css are accessible. The next sibling is | |
2539 | * guaranteed to be returned regardless of their states. | |
53fa5261 | 2540 | */ |
492eb21b TH |
2541 | struct cgroup_subsys_state * |
2542 | css_next_child(struct cgroup_subsys_state *pos_css, | |
2543 | struct cgroup_subsys_state *parent_css) | |
53fa5261 | 2544 | { |
492eb21b TH |
2545 | struct cgroup *pos = pos_css ? pos_css->cgroup : NULL; |
2546 | struct cgroup *cgrp = parent_css->cgroup; | |
53fa5261 TH |
2547 | struct cgroup *next; |
2548 | ||
ace2bee8 | 2549 | cgroup_assert_mutexes_or_rcu_locked(); |
53fa5261 TH |
2550 | |
2551 | /* | |
2552 | * @pos could already have been removed. Once a cgroup is removed, | |
2553 | * its ->sibling.next is no longer updated when its next sibling | |
ea15f8cc TH |
2554 | * changes. As CGRP_DEAD assertion is serialized and happens |
2555 | * before the cgroup is taken off the ->sibling list, if we see it | |
2556 | * unasserted, it's guaranteed that the next sibling hasn't | |
2557 | * finished its grace period even if it's already removed, and thus | |
2558 | * safe to dereference from this RCU critical section. If | |
2559 | * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed | |
2560 | * to be visible as %true here. | |
3b287a50 TH |
2561 | * |
2562 | * If @pos is dead, its next pointer can't be dereferenced; | |
2563 | * however, as each cgroup is given a monotonically increasing | |
2564 | * unique serial number and always appended to the sibling list, | |
2565 | * the next one can be found by walking the parent's children until | |
2566 | * we see a cgroup with higher serial number than @pos's. While | |
2567 | * this path can be slower, it's taken only when either the current | |
2568 | * cgroup is removed or iteration and removal race. | |
53fa5261 | 2569 | */ |
3b287a50 TH |
2570 | if (!pos) { |
2571 | next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling); | |
2572 | } else if (likely(!cgroup_is_dead(pos))) { | |
53fa5261 | 2573 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); |
3b287a50 TH |
2574 | } else { |
2575 | list_for_each_entry_rcu(next, &cgrp->children, sibling) | |
2576 | if (next->serial_nr > pos->serial_nr) | |
2577 | break; | |
53fa5261 TH |
2578 | } |
2579 | ||
492eb21b TH |
2580 | if (&next->sibling == &cgrp->children) |
2581 | return NULL; | |
2582 | ||
ca8bdcaf | 2583 | return cgroup_css(next, parent_css->ss); |
53fa5261 | 2584 | } |
53fa5261 | 2585 | |
574bd9f7 | 2586 | /** |
492eb21b | 2587 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 2588 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 2589 | * @root: css whose descendants to walk |
574bd9f7 | 2590 | * |
492eb21b | 2591 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
2592 | * to visit for pre-order traversal of @root's descendants. @root is |
2593 | * included in the iteration and the first node to be visited. | |
75501a6d | 2594 | * |
87fb54f1 TH |
2595 | * While this function requires cgroup_mutex or RCU read locking, it |
2596 | * doesn't require the whole traversal to be contained in a single critical | |
2597 | * section. This function will return the correct next descendant as long | |
2598 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
574bd9f7 | 2599 | */ |
492eb21b TH |
2600 | struct cgroup_subsys_state * |
2601 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
2602 | struct cgroup_subsys_state *root) | |
574bd9f7 | 2603 | { |
492eb21b | 2604 | struct cgroup_subsys_state *next; |
574bd9f7 | 2605 | |
ace2bee8 | 2606 | cgroup_assert_mutexes_or_rcu_locked(); |
574bd9f7 | 2607 | |
bd8815a6 | 2608 | /* if first iteration, visit @root */ |
7805d000 | 2609 | if (!pos) |
bd8815a6 | 2610 | return root; |
574bd9f7 TH |
2611 | |
2612 | /* visit the first child if exists */ | |
492eb21b | 2613 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
2614 | if (next) |
2615 | return next; | |
2616 | ||
2617 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b TH |
2618 | while (pos != root) { |
2619 | next = css_next_child(pos, css_parent(pos)); | |
75501a6d | 2620 | if (next) |
574bd9f7 | 2621 | return next; |
492eb21b | 2622 | pos = css_parent(pos); |
7805d000 | 2623 | } |
574bd9f7 TH |
2624 | |
2625 | return NULL; | |
2626 | } | |
574bd9f7 | 2627 | |
12a9d2fe | 2628 | /** |
492eb21b TH |
2629 | * css_rightmost_descendant - return the rightmost descendant of a css |
2630 | * @pos: css of interest | |
12a9d2fe | 2631 | * |
492eb21b TH |
2632 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
2633 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 2634 | * subtree of @pos. |
75501a6d | 2635 | * |
87fb54f1 TH |
2636 | * While this function requires cgroup_mutex or RCU read locking, it |
2637 | * doesn't require the whole traversal to be contained in a single critical | |
2638 | * section. This function will return the correct rightmost descendant as | |
2639 | * long as @pos is accessible. | |
12a9d2fe | 2640 | */ |
492eb21b TH |
2641 | struct cgroup_subsys_state * |
2642 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 2643 | { |
492eb21b | 2644 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 2645 | |
ace2bee8 | 2646 | cgroup_assert_mutexes_or_rcu_locked(); |
12a9d2fe TH |
2647 | |
2648 | do { | |
2649 | last = pos; | |
2650 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
2651 | pos = NULL; | |
492eb21b | 2652 | css_for_each_child(tmp, last) |
12a9d2fe TH |
2653 | pos = tmp; |
2654 | } while (pos); | |
2655 | ||
2656 | return last; | |
2657 | } | |
12a9d2fe | 2658 | |
492eb21b TH |
2659 | static struct cgroup_subsys_state * |
2660 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 2661 | { |
492eb21b | 2662 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
2663 | |
2664 | do { | |
2665 | last = pos; | |
492eb21b | 2666 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
2667 | } while (pos); |
2668 | ||
2669 | return last; | |
2670 | } | |
2671 | ||
2672 | /** | |
492eb21b | 2673 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 2674 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 2675 | * @root: css whose descendants to walk |
574bd9f7 | 2676 | * |
492eb21b | 2677 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
2678 | * to visit for post-order traversal of @root's descendants. @root is |
2679 | * included in the iteration and the last node to be visited. | |
75501a6d | 2680 | * |
87fb54f1 TH |
2681 | * While this function requires cgroup_mutex or RCU read locking, it |
2682 | * doesn't require the whole traversal to be contained in a single critical | |
2683 | * section. This function will return the correct next descendant as long | |
2684 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
2685 | * @cgroup. | |
574bd9f7 | 2686 | */ |
492eb21b TH |
2687 | struct cgroup_subsys_state * |
2688 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
2689 | struct cgroup_subsys_state *root) | |
574bd9f7 | 2690 | { |
492eb21b | 2691 | struct cgroup_subsys_state *next; |
574bd9f7 | 2692 | |
ace2bee8 | 2693 | cgroup_assert_mutexes_or_rcu_locked(); |
574bd9f7 | 2694 | |
58b79a91 TH |
2695 | /* if first iteration, visit leftmost descendant which may be @root */ |
2696 | if (!pos) | |
2697 | return css_leftmost_descendant(root); | |
574bd9f7 | 2698 | |
bd8815a6 TH |
2699 | /* if we visited @root, we're done */ |
2700 | if (pos == root) | |
2701 | return NULL; | |
2702 | ||
574bd9f7 | 2703 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
492eb21b | 2704 | next = css_next_child(pos, css_parent(pos)); |
75501a6d | 2705 | if (next) |
492eb21b | 2706 | return css_leftmost_descendant(next); |
574bd9f7 TH |
2707 | |
2708 | /* no sibling left, visit parent */ | |
bd8815a6 | 2709 | return css_parent(pos); |
574bd9f7 | 2710 | } |
574bd9f7 | 2711 | |
0942eeee | 2712 | /** |
72ec7029 | 2713 | * css_advance_task_iter - advance a task itererator to the next css_set |
0942eeee TH |
2714 | * @it: the iterator to advance |
2715 | * | |
2716 | * Advance @it to the next css_set to walk. | |
d515876e | 2717 | */ |
72ec7029 | 2718 | static void css_advance_task_iter(struct css_task_iter *it) |
d515876e TH |
2719 | { |
2720 | struct list_head *l = it->cset_link; | |
2721 | struct cgrp_cset_link *link; | |
2722 | struct css_set *cset; | |
2723 | ||
2724 | /* Advance to the next non-empty css_set */ | |
2725 | do { | |
2726 | l = l->next; | |
72ec7029 | 2727 | if (l == &it->origin_css->cgroup->cset_links) { |
d515876e TH |
2728 | it->cset_link = NULL; |
2729 | return; | |
2730 | } | |
2731 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
2732 | cset = link->cset; | |
c7561128 TH |
2733 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); |
2734 | ||
d515876e | 2735 | it->cset_link = l; |
c7561128 TH |
2736 | |
2737 | if (!list_empty(&cset->tasks)) | |
2738 | it->task = cset->tasks.next; | |
2739 | else | |
2740 | it->task = cset->mg_tasks.next; | |
d515876e TH |
2741 | } |
2742 | ||
0942eeee | 2743 | /** |
72ec7029 TH |
2744 | * css_task_iter_start - initiate task iteration |
2745 | * @css: the css to walk tasks of | |
0942eeee TH |
2746 | * @it: the task iterator to use |
2747 | * | |
72ec7029 TH |
2748 | * Initiate iteration through the tasks of @css. The caller can call |
2749 | * css_task_iter_next() to walk through the tasks until the function | |
2750 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
2751 | * called. | |
0942eeee TH |
2752 | * |
2753 | * Note that this function acquires a lock which is released when the | |
2754 | * iteration finishes. The caller can't sleep while iteration is in | |
2755 | * progress. | |
2756 | */ | |
72ec7029 TH |
2757 | void css_task_iter_start(struct cgroup_subsys_state *css, |
2758 | struct css_task_iter *it) | |
96d365e0 | 2759 | __acquires(css_set_rwsem) |
817929ec | 2760 | { |
56fde9e0 TH |
2761 | /* no one should try to iterate before mounting cgroups */ |
2762 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 2763 | |
96d365e0 | 2764 | down_read(&css_set_rwsem); |
c59cd3d8 | 2765 | |
72ec7029 TH |
2766 | it->origin_css = css; |
2767 | it->cset_link = &css->cgroup->cset_links; | |
c59cd3d8 | 2768 | |
72ec7029 | 2769 | css_advance_task_iter(it); |
817929ec PM |
2770 | } |
2771 | ||
0942eeee | 2772 | /** |
72ec7029 | 2773 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
2774 | * @it: the task iterator being iterated |
2775 | * | |
2776 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
2777 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
2778 | * reaches the end. | |
0942eeee | 2779 | */ |
72ec7029 | 2780 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec PM |
2781 | { |
2782 | struct task_struct *res; | |
2783 | struct list_head *l = it->task; | |
c7561128 TH |
2784 | struct cgrp_cset_link *link = list_entry(it->cset_link, |
2785 | struct cgrp_cset_link, cset_link); | |
817929ec PM |
2786 | |
2787 | /* If the iterator cg is NULL, we have no tasks */ | |
69d0206c | 2788 | if (!it->cset_link) |
817929ec PM |
2789 | return NULL; |
2790 | res = list_entry(l, struct task_struct, cg_list); | |
c7561128 TH |
2791 | |
2792 | /* | |
2793 | * Advance iterator to find next entry. cset->tasks is consumed | |
2794 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
2795 | * next cset. | |
2796 | */ | |
817929ec | 2797 | l = l->next; |
c7561128 TH |
2798 | |
2799 | if (l == &link->cset->tasks) | |
2800 | l = link->cset->mg_tasks.next; | |
2801 | ||
2802 | if (l == &link->cset->mg_tasks) | |
72ec7029 | 2803 | css_advance_task_iter(it); |
c7561128 | 2804 | else |
817929ec | 2805 | it->task = l; |
c7561128 | 2806 | |
817929ec PM |
2807 | return res; |
2808 | } | |
2809 | ||
0942eeee | 2810 | /** |
72ec7029 | 2811 | * css_task_iter_end - finish task iteration |
0942eeee TH |
2812 | * @it: the task iterator to finish |
2813 | * | |
72ec7029 | 2814 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 2815 | */ |
72ec7029 | 2816 | void css_task_iter_end(struct css_task_iter *it) |
96d365e0 | 2817 | __releases(css_set_rwsem) |
817929ec | 2818 | { |
96d365e0 | 2819 | up_read(&css_set_rwsem); |
817929ec PM |
2820 | } |
2821 | ||
8cc99345 TH |
2822 | /** |
2823 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another | |
2824 | * @to: cgroup to which the tasks will be moved | |
2825 | * @from: cgroup in which the tasks currently reside | |
eaf797ab TH |
2826 | * |
2827 | * Locking rules between cgroup_post_fork() and the migration path | |
2828 | * guarantee that, if a task is forking while being migrated, the new child | |
2829 | * is guaranteed to be either visible in the source cgroup after the | |
2830 | * parent's migration is complete or put into the target cgroup. No task | |
2831 | * can slip out of migration through forking. | |
8cc99345 TH |
2832 | */ |
2833 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) | |
2834 | { | |
e406d1cf TH |
2835 | struct css_task_iter it; |
2836 | struct task_struct *task; | |
2837 | int ret = 0; | |
2838 | ||
2839 | do { | |
2840 | css_task_iter_start(&from->dummy_css, &it); | |
2841 | task = css_task_iter_next(&it); | |
2842 | if (task) | |
2843 | get_task_struct(task); | |
2844 | css_task_iter_end(&it); | |
2845 | ||
2846 | if (task) { | |
2847 | mutex_lock(&cgroup_mutex); | |
2848 | ret = cgroup_attach_task(to, task, false); | |
2849 | mutex_unlock(&cgroup_mutex); | |
2850 | put_task_struct(task); | |
2851 | } | |
2852 | } while (task && !ret); | |
2853 | ||
2854 | return ret; | |
8cc99345 TH |
2855 | } |
2856 | ||
bbcb81d0 | 2857 | /* |
102a775e | 2858 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
2859 | * |
2860 | * Reading this file can return large amounts of data if a cgroup has | |
2861 | * *lots* of attached tasks. So it may need several calls to read(), | |
2862 | * but we cannot guarantee that the information we produce is correct | |
2863 | * unless we produce it entirely atomically. | |
2864 | * | |
bbcb81d0 | 2865 | */ |
bbcb81d0 | 2866 | |
24528255 LZ |
2867 | /* which pidlist file are we talking about? */ |
2868 | enum cgroup_filetype { | |
2869 | CGROUP_FILE_PROCS, | |
2870 | CGROUP_FILE_TASKS, | |
2871 | }; | |
2872 | ||
2873 | /* | |
2874 | * A pidlist is a list of pids that virtually represents the contents of one | |
2875 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
2876 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
2877 | * to the cgroup. | |
2878 | */ | |
2879 | struct cgroup_pidlist { | |
2880 | /* | |
2881 | * used to find which pidlist is wanted. doesn't change as long as | |
2882 | * this particular list stays in the list. | |
2883 | */ | |
2884 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
2885 | /* array of xids */ | |
2886 | pid_t *list; | |
2887 | /* how many elements the above list has */ | |
2888 | int length; | |
24528255 LZ |
2889 | /* each of these stored in a list by its cgroup */ |
2890 | struct list_head links; | |
2891 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
2892 | struct cgroup *owner; | |
b1a21367 TH |
2893 | /* for delayed destruction */ |
2894 | struct delayed_work destroy_dwork; | |
24528255 LZ |
2895 | }; |
2896 | ||
d1d9fd33 BB |
2897 | /* |
2898 | * The following two functions "fix" the issue where there are more pids | |
2899 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
2900 | * TODO: replace with a kernel-wide solution to this problem | |
2901 | */ | |
2902 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
2903 | static void *pidlist_allocate(int count) | |
2904 | { | |
2905 | if (PIDLIST_TOO_LARGE(count)) | |
2906 | return vmalloc(count * sizeof(pid_t)); | |
2907 | else | |
2908 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
2909 | } | |
b1a21367 | 2910 | |
d1d9fd33 BB |
2911 | static void pidlist_free(void *p) |
2912 | { | |
2913 | if (is_vmalloc_addr(p)) | |
2914 | vfree(p); | |
2915 | else | |
2916 | kfree(p); | |
2917 | } | |
d1d9fd33 | 2918 | |
b1a21367 TH |
2919 | /* |
2920 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
2921 | * should be left afterwards. | |
2922 | */ | |
2923 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
2924 | { | |
2925 | struct cgroup_pidlist *l, *tmp_l; | |
2926 | ||
2927 | mutex_lock(&cgrp->pidlist_mutex); | |
2928 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
2929 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
2930 | mutex_unlock(&cgrp->pidlist_mutex); | |
2931 | ||
2932 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
2933 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
2934 | } | |
2935 | ||
2936 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
2937 | { | |
2938 | struct delayed_work *dwork = to_delayed_work(work); | |
2939 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
2940 | destroy_dwork); | |
2941 | struct cgroup_pidlist *tofree = NULL; | |
2942 | ||
2943 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
2944 | |
2945 | /* | |
04502365 TH |
2946 | * Destroy iff we didn't get queued again. The state won't change |
2947 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 2948 | */ |
04502365 | 2949 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
2950 | list_del(&l->links); |
2951 | pidlist_free(l->list); | |
2952 | put_pid_ns(l->key.ns); | |
2953 | tofree = l; | |
2954 | } | |
2955 | ||
b1a21367 TH |
2956 | mutex_unlock(&l->owner->pidlist_mutex); |
2957 | kfree(tofree); | |
2958 | } | |
2959 | ||
bbcb81d0 | 2960 | /* |
102a775e | 2961 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 2962 | * Returns the number of unique elements. |
bbcb81d0 | 2963 | */ |
6ee211ad | 2964 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 2965 | { |
102a775e | 2966 | int src, dest = 1; |
102a775e BB |
2967 | |
2968 | /* | |
2969 | * we presume the 0th element is unique, so i starts at 1. trivial | |
2970 | * edge cases first; no work needs to be done for either | |
2971 | */ | |
2972 | if (length == 0 || length == 1) | |
2973 | return length; | |
2974 | /* src and dest walk down the list; dest counts unique elements */ | |
2975 | for (src = 1; src < length; src++) { | |
2976 | /* find next unique element */ | |
2977 | while (list[src] == list[src-1]) { | |
2978 | src++; | |
2979 | if (src == length) | |
2980 | goto after; | |
2981 | } | |
2982 | /* dest always points to where the next unique element goes */ | |
2983 | list[dest] = list[src]; | |
2984 | dest++; | |
2985 | } | |
2986 | after: | |
102a775e BB |
2987 | return dest; |
2988 | } | |
2989 | ||
afb2bc14 TH |
2990 | /* |
2991 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
2992 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
2993 | * different per namespace, each namespace needs differently sorted list, | |
2994 | * making it impossible to use, for example, single rbtree of member tasks | |
2995 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
2996 | * per open file is dangerous, so cgroup had to implement shared pool of | |
2997 | * pidlists keyed by cgroup and namespace. | |
2998 | * | |
2999 | * All this extra complexity was caused by the original implementation | |
3000 | * committing to an entirely unnecessary property. In the long term, we | |
3001 | * want to do away with it. Explicitly scramble sort order if | |
3002 | * sane_behavior so that no such expectation exists in the new interface. | |
3003 | * | |
3004 | * Scrambling is done by swapping every two consecutive bits, which is | |
3005 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
3006 | */ | |
3007 | static pid_t pid_fry(pid_t pid) | |
3008 | { | |
3009 | unsigned a = pid & 0x55555555; | |
3010 | unsigned b = pid & 0xAAAAAAAA; | |
3011 | ||
3012 | return (a << 1) | (b >> 1); | |
3013 | } | |
3014 | ||
3015 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
3016 | { | |
3017 | if (cgroup_sane_behavior(cgrp)) | |
3018 | return pid_fry(pid); | |
3019 | else | |
3020 | return pid; | |
3021 | } | |
3022 | ||
102a775e BB |
3023 | static int cmppid(const void *a, const void *b) |
3024 | { | |
3025 | return *(pid_t *)a - *(pid_t *)b; | |
3026 | } | |
3027 | ||
afb2bc14 TH |
3028 | static int fried_cmppid(const void *a, const void *b) |
3029 | { | |
3030 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
3031 | } | |
3032 | ||
e6b81710 TH |
3033 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
3034 | enum cgroup_filetype type) | |
3035 | { | |
3036 | struct cgroup_pidlist *l; | |
3037 | /* don't need task_nsproxy() if we're looking at ourself */ | |
3038 | struct pid_namespace *ns = task_active_pid_ns(current); | |
3039 | ||
3040 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
3041 | ||
3042 | list_for_each_entry(l, &cgrp->pidlists, links) | |
3043 | if (l->key.type == type && l->key.ns == ns) | |
3044 | return l; | |
3045 | return NULL; | |
3046 | } | |
3047 | ||
72a8cb30 BB |
3048 | /* |
3049 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3050 | * returns with the lock on that pidlist already held, and takes care | |
3051 | * of the use count, or returns NULL with no locks held if we're out of | |
3052 | * memory. | |
3053 | */ | |
e6b81710 TH |
3054 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
3055 | enum cgroup_filetype type) | |
72a8cb30 BB |
3056 | { |
3057 | struct cgroup_pidlist *l; | |
b70cc5fd | 3058 | |
e6b81710 TH |
3059 | lockdep_assert_held(&cgrp->pidlist_mutex); |
3060 | ||
3061 | l = cgroup_pidlist_find(cgrp, type); | |
3062 | if (l) | |
3063 | return l; | |
3064 | ||
72a8cb30 | 3065 | /* entry not found; create a new one */ |
f4f4be2b | 3066 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 3067 | if (!l) |
72a8cb30 | 3068 | return l; |
e6b81710 | 3069 | |
b1a21367 | 3070 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 3071 | l->key.type = type; |
e6b81710 TH |
3072 | /* don't need task_nsproxy() if we're looking at ourself */ |
3073 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
3074 | l->owner = cgrp; |
3075 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
3076 | return l; |
3077 | } | |
3078 | ||
102a775e BB |
3079 | /* |
3080 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3081 | */ | |
72a8cb30 BB |
3082 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3083 | struct cgroup_pidlist **lp) | |
102a775e BB |
3084 | { |
3085 | pid_t *array; | |
3086 | int length; | |
3087 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 3088 | struct css_task_iter it; |
817929ec | 3089 | struct task_struct *tsk; |
102a775e BB |
3090 | struct cgroup_pidlist *l; |
3091 | ||
4bac00d1 TH |
3092 | lockdep_assert_held(&cgrp->pidlist_mutex); |
3093 | ||
102a775e BB |
3094 | /* |
3095 | * If cgroup gets more users after we read count, we won't have | |
3096 | * enough space - tough. This race is indistinguishable to the | |
3097 | * caller from the case that the additional cgroup users didn't | |
3098 | * show up until sometime later on. | |
3099 | */ | |
3100 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3101 | array = pidlist_allocate(length); |
102a775e BB |
3102 | if (!array) |
3103 | return -ENOMEM; | |
3104 | /* now, populate the array */ | |
72ec7029 TH |
3105 | css_task_iter_start(&cgrp->dummy_css, &it); |
3106 | while ((tsk = css_task_iter_next(&it))) { | |
102a775e | 3107 | if (unlikely(n == length)) |
817929ec | 3108 | break; |
102a775e | 3109 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3110 | if (type == CGROUP_FILE_PROCS) |
3111 | pid = task_tgid_vnr(tsk); | |
3112 | else | |
3113 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3114 | if (pid > 0) /* make sure to only use valid results */ |
3115 | array[n++] = pid; | |
817929ec | 3116 | } |
72ec7029 | 3117 | css_task_iter_end(&it); |
102a775e BB |
3118 | length = n; |
3119 | /* now sort & (if procs) strip out duplicates */ | |
afb2bc14 TH |
3120 | if (cgroup_sane_behavior(cgrp)) |
3121 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); | |
3122 | else | |
3123 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3124 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 3125 | length = pidlist_uniq(array, length); |
e6b81710 | 3126 | |
e6b81710 | 3127 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 3128 | if (!l) { |
e6b81710 | 3129 | mutex_unlock(&cgrp->pidlist_mutex); |
d1d9fd33 | 3130 | pidlist_free(array); |
72a8cb30 | 3131 | return -ENOMEM; |
102a775e | 3132 | } |
e6b81710 TH |
3133 | |
3134 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 3135 | pidlist_free(l->list); |
102a775e BB |
3136 | l->list = array; |
3137 | l->length = length; | |
72a8cb30 | 3138 | *lp = l; |
102a775e | 3139 | return 0; |
bbcb81d0 PM |
3140 | } |
3141 | ||
846c7bb0 | 3142 | /** |
a043e3b2 | 3143 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3144 | * @stats: cgroupstats to fill information into |
3145 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3146 | * been requested. | |
a043e3b2 LZ |
3147 | * |
3148 | * Build and fill cgroupstats so that taskstats can export it to user | |
3149 | * space. | |
846c7bb0 BS |
3150 | */ |
3151 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3152 | { | |
2bd59d48 | 3153 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 3154 | struct cgroup *cgrp; |
72ec7029 | 3155 | struct css_task_iter it; |
846c7bb0 | 3156 | struct task_struct *tsk; |
33d283be | 3157 | |
2bd59d48 TH |
3158 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
3159 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
3160 | kernfs_type(kn) != KERNFS_DIR) | |
3161 | return -EINVAL; | |
3162 | ||
bad34660 LZ |
3163 | mutex_lock(&cgroup_mutex); |
3164 | ||
846c7bb0 | 3165 | /* |
2bd59d48 TH |
3166 | * We aren't being called from kernfs and there's no guarantee on |
3167 | * @kn->priv's validity. For this and css_tryget_from_dir(), | |
3168 | * @kn->priv is RCU safe. Let's do the RCU dancing. | |
846c7bb0 | 3169 | */ |
2bd59d48 TH |
3170 | rcu_read_lock(); |
3171 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 3172 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 3173 | rcu_read_unlock(); |
bad34660 | 3174 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
3175 | return -ENOENT; |
3176 | } | |
bad34660 | 3177 | rcu_read_unlock(); |
846c7bb0 | 3178 | |
72ec7029 TH |
3179 | css_task_iter_start(&cgrp->dummy_css, &it); |
3180 | while ((tsk = css_task_iter_next(&it))) { | |
846c7bb0 BS |
3181 | switch (tsk->state) { |
3182 | case TASK_RUNNING: | |
3183 | stats->nr_running++; | |
3184 | break; | |
3185 | case TASK_INTERRUPTIBLE: | |
3186 | stats->nr_sleeping++; | |
3187 | break; | |
3188 | case TASK_UNINTERRUPTIBLE: | |
3189 | stats->nr_uninterruptible++; | |
3190 | break; | |
3191 | case TASK_STOPPED: | |
3192 | stats->nr_stopped++; | |
3193 | break; | |
3194 | default: | |
3195 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3196 | stats->nr_io_wait++; | |
3197 | break; | |
3198 | } | |
3199 | } | |
72ec7029 | 3200 | css_task_iter_end(&it); |
846c7bb0 | 3201 | |
bad34660 | 3202 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 3203 | return 0; |
846c7bb0 BS |
3204 | } |
3205 | ||
8f3ff208 | 3206 | |
bbcb81d0 | 3207 | /* |
102a775e | 3208 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3209 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3210 | * in the cgroup->l->list array. |
bbcb81d0 | 3211 | */ |
cc31edce | 3212 | |
102a775e | 3213 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3214 | { |
cc31edce PM |
3215 | /* |
3216 | * Initially we receive a position value that corresponds to | |
3217 | * one more than the last pid shown (or 0 on the first call or | |
3218 | * after a seek to the start). Use a binary-search to find the | |
3219 | * next pid to display, if any | |
3220 | */ | |
2bd59d48 | 3221 | struct kernfs_open_file *of = s->private; |
7da11279 | 3222 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 3223 | struct cgroup_pidlist *l; |
7da11279 | 3224 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 3225 | int index = 0, pid = *pos; |
4bac00d1 TH |
3226 | int *iter, ret; |
3227 | ||
3228 | mutex_lock(&cgrp->pidlist_mutex); | |
3229 | ||
3230 | /* | |
5d22444f | 3231 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 3232 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 3233 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
3234 | * could already have been destroyed. |
3235 | */ | |
5d22444f TH |
3236 | if (of->priv) |
3237 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
3238 | |
3239 | /* | |
3240 | * Either this is the first start() after open or the matching | |
3241 | * pidlist has been destroyed inbetween. Create a new one. | |
3242 | */ | |
5d22444f TH |
3243 | if (!of->priv) { |
3244 | ret = pidlist_array_load(cgrp, type, | |
3245 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
3246 | if (ret) |
3247 | return ERR_PTR(ret); | |
3248 | } | |
5d22444f | 3249 | l = of->priv; |
cc31edce | 3250 | |
cc31edce | 3251 | if (pid) { |
102a775e | 3252 | int end = l->length; |
20777766 | 3253 | |
cc31edce PM |
3254 | while (index < end) { |
3255 | int mid = (index + end) / 2; | |
afb2bc14 | 3256 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
3257 | index = mid; |
3258 | break; | |
afb2bc14 | 3259 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
3260 | index = mid + 1; |
3261 | else | |
3262 | end = mid; | |
3263 | } | |
3264 | } | |
3265 | /* If we're off the end of the array, we're done */ | |
102a775e | 3266 | if (index >= l->length) |
cc31edce PM |
3267 | return NULL; |
3268 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3269 | iter = l->list + index; |
afb2bc14 | 3270 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
3271 | return iter; |
3272 | } | |
3273 | ||
102a775e | 3274 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3275 | { |
2bd59d48 | 3276 | struct kernfs_open_file *of = s->private; |
5d22444f | 3277 | struct cgroup_pidlist *l = of->priv; |
62236858 | 3278 | |
5d22444f TH |
3279 | if (l) |
3280 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 3281 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 3282 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
3283 | } |
3284 | ||
102a775e | 3285 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3286 | { |
2bd59d48 | 3287 | struct kernfs_open_file *of = s->private; |
5d22444f | 3288 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
3289 | pid_t *p = v; |
3290 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3291 | /* |
3292 | * Advance to the next pid in the array. If this goes off the | |
3293 | * end, we're done | |
3294 | */ | |
3295 | p++; | |
3296 | if (p >= end) { | |
3297 | return NULL; | |
3298 | } else { | |
7da11279 | 3299 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
3300 | return p; |
3301 | } | |
3302 | } | |
3303 | ||
102a775e | 3304 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3305 | { |
3306 | return seq_printf(s, "%d\n", *(int *)v); | |
3307 | } | |
bbcb81d0 | 3308 | |
102a775e BB |
3309 | /* |
3310 | * seq_operations functions for iterating on pidlists through seq_file - | |
3311 | * independent of whether it's tasks or procs | |
3312 | */ | |
3313 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3314 | .start = cgroup_pidlist_start, | |
3315 | .stop = cgroup_pidlist_stop, | |
3316 | .next = cgroup_pidlist_next, | |
3317 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3318 | }; |
3319 | ||
182446d0 TH |
3320 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
3321 | struct cftype *cft) | |
81a6a5cd | 3322 | { |
182446d0 | 3323 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
3324 | } |
3325 | ||
182446d0 TH |
3326 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
3327 | struct cftype *cft, u64 val) | |
6379c106 | 3328 | { |
182446d0 | 3329 | clear_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
6379c106 | 3330 | if (val) |
182446d0 | 3331 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 3332 | else |
182446d0 | 3333 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
3334 | return 0; |
3335 | } | |
3336 | ||
182446d0 TH |
3337 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
3338 | struct cftype *cft) | |
97978e6d | 3339 | { |
182446d0 | 3340 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
3341 | } |
3342 | ||
182446d0 TH |
3343 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
3344 | struct cftype *cft, u64 val) | |
97978e6d DL |
3345 | { |
3346 | if (val) | |
182446d0 | 3347 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 3348 | else |
182446d0 | 3349 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
3350 | return 0; |
3351 | } | |
3352 | ||
d5c56ced | 3353 | static struct cftype cgroup_base_files[] = { |
81a6a5cd | 3354 | { |
d5c56ced | 3355 | .name = "cgroup.procs", |
6612f05b TH |
3356 | .seq_start = cgroup_pidlist_start, |
3357 | .seq_next = cgroup_pidlist_next, | |
3358 | .seq_stop = cgroup_pidlist_stop, | |
3359 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 3360 | .private = CGROUP_FILE_PROCS, |
74a1166d | 3361 | .write_u64 = cgroup_procs_write, |
74a1166d | 3362 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 3363 | }, |
97978e6d DL |
3364 | { |
3365 | .name = "cgroup.clone_children", | |
873fe09e | 3366 | .flags = CFTYPE_INSANE, |
97978e6d DL |
3367 | .read_u64 = cgroup_clone_children_read, |
3368 | .write_u64 = cgroup_clone_children_write, | |
3369 | }, | |
873fe09e TH |
3370 | { |
3371 | .name = "cgroup.sane_behavior", | |
3372 | .flags = CFTYPE_ONLY_ON_ROOT, | |
2da8ca82 | 3373 | .seq_show = cgroup_sane_behavior_show, |
873fe09e | 3374 | }, |
d5c56ced TH |
3375 | |
3376 | /* | |
3377 | * Historical crazy stuff. These don't have "cgroup." prefix and | |
3378 | * don't exist if sane_behavior. If you're depending on these, be | |
3379 | * prepared to be burned. | |
3380 | */ | |
3381 | { | |
3382 | .name = "tasks", | |
3383 | .flags = CFTYPE_INSANE, /* use "procs" instead */ | |
6612f05b TH |
3384 | .seq_start = cgroup_pidlist_start, |
3385 | .seq_next = cgroup_pidlist_next, | |
3386 | .seq_stop = cgroup_pidlist_stop, | |
3387 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 3388 | .private = CGROUP_FILE_TASKS, |
d5c56ced | 3389 | .write_u64 = cgroup_tasks_write, |
d5c56ced TH |
3390 | .mode = S_IRUGO | S_IWUSR, |
3391 | }, | |
3392 | { | |
3393 | .name = "notify_on_release", | |
3394 | .flags = CFTYPE_INSANE, | |
3395 | .read_u64 = cgroup_read_notify_on_release, | |
3396 | .write_u64 = cgroup_write_notify_on_release, | |
3397 | }, | |
6e6ff25b TH |
3398 | { |
3399 | .name = "release_agent", | |
cc5943a7 | 3400 | .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 3401 | .seq_show = cgroup_release_agent_show, |
6e6ff25b | 3402 | .write_string = cgroup_release_agent_write, |
5f469907 | 3403 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 3404 | }, |
db0416b6 | 3405 | { } /* terminate */ |
bbcb81d0 PM |
3406 | }; |
3407 | ||
13af07df | 3408 | /** |
628f7cd4 | 3409 | * cgroup_populate_dir - create subsys files in a cgroup directory |
13af07df | 3410 | * @cgrp: target cgroup |
13af07df | 3411 | * @subsys_mask: mask of the subsystem ids whose files should be added |
bee55099 TH |
3412 | * |
3413 | * On failure, no file is added. | |
13af07df | 3414 | */ |
628f7cd4 | 3415 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
ddbcc7e8 | 3416 | { |
ddbcc7e8 | 3417 | struct cgroup_subsys *ss; |
b420ba7d | 3418 | int i, ret = 0; |
bbcb81d0 | 3419 | |
8e3f6541 | 3420 | /* process cftsets of each subsystem */ |
b420ba7d | 3421 | for_each_subsys(ss, i) { |
0adb0704 | 3422 | struct cftype *cfts; |
b420ba7d TH |
3423 | |
3424 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 3425 | continue; |
8e3f6541 | 3426 | |
0adb0704 TH |
3427 | list_for_each_entry(cfts, &ss->cfts, node) { |
3428 | ret = cgroup_addrm_files(cgrp, cfts, true); | |
bee55099 TH |
3429 | if (ret < 0) |
3430 | goto err; | |
3431 | } | |
ddbcc7e8 | 3432 | } |
ddbcc7e8 | 3433 | return 0; |
bee55099 TH |
3434 | err: |
3435 | cgroup_clear_dir(cgrp, subsys_mask); | |
3436 | return ret; | |
ddbcc7e8 PM |
3437 | } |
3438 | ||
0c21ead1 TH |
3439 | /* |
3440 | * css destruction is four-stage process. | |
3441 | * | |
3442 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
3443 | * Implemented in kill_css(). | |
3444 | * | |
3445 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
3446 | * and thus css_tryget() is guaranteed to fail, the css can be offlined | |
3447 | * by invoking offline_css(). After offlining, the base ref is put. | |
3448 | * Implemented in css_killed_work_fn(). | |
3449 | * | |
3450 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
3451 | * accessors are inside RCU read sections. css_release() schedules the | |
3452 | * RCU callback. | |
3453 | * | |
3454 | * 4. After the grace period, the css can be freed. Implemented in | |
3455 | * css_free_work_fn(). | |
3456 | * | |
3457 | * It is actually hairier because both step 2 and 4 require process context | |
3458 | * and thus involve punting to css->destroy_work adding two additional | |
3459 | * steps to the already complex sequence. | |
3460 | */ | |
35ef10da | 3461 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
3462 | { |
3463 | struct cgroup_subsys_state *css = | |
35ef10da | 3464 | container_of(work, struct cgroup_subsys_state, destroy_work); |
0c21ead1 | 3465 | struct cgroup *cgrp = css->cgroup; |
48ddbe19 | 3466 | |
0ae78e0b TH |
3467 | if (css->parent) |
3468 | css_put(css->parent); | |
3469 | ||
0c21ead1 | 3470 | css->ss->css_free(css); |
2bd59d48 | 3471 | cgroup_put(cgrp); |
48ddbe19 TH |
3472 | } |
3473 | ||
0c21ead1 | 3474 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
3475 | { |
3476 | struct cgroup_subsys_state *css = | |
0c21ead1 | 3477 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 3478 | |
35ef10da | 3479 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 3480 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
3481 | } |
3482 | ||
d3daf28d TH |
3483 | static void css_release(struct percpu_ref *ref) |
3484 | { | |
3485 | struct cgroup_subsys_state *css = | |
3486 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
3487 | ||
aec25020 | 3488 | rcu_assign_pointer(css->cgroup->subsys[css->ss->id], NULL); |
0c21ead1 | 3489 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
3490 | } |
3491 | ||
623f926b TH |
3492 | static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss, |
3493 | struct cgroup *cgrp) | |
ddbcc7e8 | 3494 | { |
bd89aabc | 3495 | css->cgroup = cgrp; |
72c97e54 | 3496 | css->ss = ss; |
ddbcc7e8 | 3497 | css->flags = 0; |
0ae78e0b TH |
3498 | |
3499 | if (cgrp->parent) | |
ca8bdcaf | 3500 | css->parent = cgroup_css(cgrp->parent, ss); |
0ae78e0b | 3501 | else |
38b53aba | 3502 | css->flags |= CSS_ROOT; |
48ddbe19 | 3503 | |
ca8bdcaf | 3504 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
3505 | } |
3506 | ||
2a4ac633 | 3507 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 3508 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 3509 | { |
623f926b | 3510 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
3511 | int ret = 0; |
3512 | ||
ace2bee8 | 3513 | lockdep_assert_held(&cgroup_tree_mutex); |
a31f2d3f TH |
3514 | lockdep_assert_held(&cgroup_mutex); |
3515 | ||
92fb9748 | 3516 | if (ss->css_online) |
eb95419b | 3517 | ret = ss->css_online(css); |
ae7f164a | 3518 | if (!ret) { |
eb95419b | 3519 | css->flags |= CSS_ONLINE; |
f20104de | 3520 | css->cgroup->nr_css++; |
aec25020 | 3521 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 3522 | } |
b1929db4 | 3523 | return ret; |
a31f2d3f TH |
3524 | } |
3525 | ||
2a4ac633 | 3526 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 3527 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 3528 | { |
623f926b | 3529 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f | 3530 | |
ace2bee8 | 3531 | lockdep_assert_held(&cgroup_tree_mutex); |
a31f2d3f TH |
3532 | lockdep_assert_held(&cgroup_mutex); |
3533 | ||
3534 | if (!(css->flags & CSS_ONLINE)) | |
3535 | return; | |
3536 | ||
d7eeac19 | 3537 | if (ss->css_offline) |
eb95419b | 3538 | ss->css_offline(css); |
a31f2d3f | 3539 | |
eb95419b | 3540 | css->flags &= ~CSS_ONLINE; |
09a503ea | 3541 | css->cgroup->nr_css--; |
aec25020 | 3542 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], css); |
a31f2d3f TH |
3543 | } |
3544 | ||
c81c925a TH |
3545 | /** |
3546 | * create_css - create a cgroup_subsys_state | |
3547 | * @cgrp: the cgroup new css will be associated with | |
3548 | * @ss: the subsys of new css | |
3549 | * | |
3550 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
3551 | * css is online and installed in @cgrp with all interface files created. | |
3552 | * Returns 0 on success, -errno on failure. | |
3553 | */ | |
3554 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) | |
3555 | { | |
3556 | struct cgroup *parent = cgrp->parent; | |
3557 | struct cgroup_subsys_state *css; | |
3558 | int err; | |
3559 | ||
c81c925a TH |
3560 | lockdep_assert_held(&cgroup_mutex); |
3561 | ||
3562 | css = ss->css_alloc(cgroup_css(parent, ss)); | |
3563 | if (IS_ERR(css)) | |
3564 | return PTR_ERR(css); | |
3565 | ||
3566 | err = percpu_ref_init(&css->refcnt, css_release); | |
3567 | if (err) | |
3568 | goto err_free; | |
3569 | ||
3570 | init_css(css, ss, cgrp); | |
3571 | ||
aec25020 | 3572 | err = cgroup_populate_dir(cgrp, 1 << ss->id); |
c81c925a TH |
3573 | if (err) |
3574 | goto err_free; | |
3575 | ||
3576 | err = online_css(css); | |
3577 | if (err) | |
3578 | goto err_free; | |
3579 | ||
59f5296b | 3580 | cgroup_get(cgrp); |
c81c925a TH |
3581 | css_get(css->parent); |
3582 | ||
3583 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && | |
3584 | parent->parent) { | |
3585 | 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", | |
3586 | current->comm, current->pid, ss->name); | |
3587 | if (!strcmp(ss->name, "memory")) | |
3588 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
3589 | ss->warned_broken_hierarchy = true; | |
3590 | } | |
3591 | ||
3592 | return 0; | |
3593 | ||
3594 | err_free: | |
3595 | percpu_ref_cancel_init(&css->refcnt); | |
3596 | ss->css_free(css); | |
3597 | return err; | |
3598 | } | |
3599 | ||
2bd59d48 | 3600 | /** |
a043e3b2 LZ |
3601 | * cgroup_create - create a cgroup |
3602 | * @parent: cgroup that will be parent of the new cgroup | |
e61734c5 | 3603 | * @name: name of the new cgroup |
2bd59d48 | 3604 | * @mode: mode to set on new cgroup |
ddbcc7e8 | 3605 | */ |
e61734c5 | 3606 | static long cgroup_create(struct cgroup *parent, const char *name, |
2bd59d48 | 3607 | umode_t mode) |
ddbcc7e8 | 3608 | { |
bd89aabc | 3609 | struct cgroup *cgrp; |
ddbcc7e8 | 3610 | struct cgroupfs_root *root = parent->root; |
b58c8998 | 3611 | int ssid, err; |
ddbcc7e8 | 3612 | struct cgroup_subsys *ss; |
2bd59d48 | 3613 | struct kernfs_node *kn; |
ddbcc7e8 | 3614 | |
0a950f65 | 3615 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc PM |
3616 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
3617 | if (!cgrp) | |
ddbcc7e8 PM |
3618 | return -ENOMEM; |
3619 | ||
ace2bee8 TH |
3620 | mutex_lock(&cgroup_tree_mutex); |
3621 | ||
976c06bc TH |
3622 | /* |
3623 | * Only live parents can have children. Note that the liveliness | |
3624 | * check isn't strictly necessary because cgroup_mkdir() and | |
3625 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
3626 | * anyway so that locking is contained inside cgroup proper and we | |
3627 | * don't get nasty surprises if we ever grow another caller. | |
3628 | */ | |
3629 | if (!cgroup_lock_live_group(parent)) { | |
3630 | err = -ENODEV; | |
ace2bee8 | 3631 | goto err_unlock_tree; |
0ab02ca8 LZ |
3632 | } |
3633 | ||
3634 | /* | |
3635 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
3636 | * a half-baked cgroup. | |
3637 | */ | |
3638 | cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL); | |
3639 | if (cgrp->id < 0) { | |
3640 | err = -ENOMEM; | |
3641 | goto err_unlock; | |
976c06bc TH |
3642 | } |
3643 | ||
cc31edce | 3644 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 3645 | |
bd89aabc | 3646 | cgrp->parent = parent; |
0ae78e0b | 3647 | cgrp->dummy_css.parent = &parent->dummy_css; |
bd89aabc | 3648 | cgrp->root = parent->root; |
ddbcc7e8 | 3649 | |
b6abdb0e LZ |
3650 | if (notify_on_release(parent)) |
3651 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3652 | ||
2260e7fc TH |
3653 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
3654 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 3655 | |
2bd59d48 | 3656 | /* create the directory */ |
e61734c5 | 3657 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 TH |
3658 | if (IS_ERR(kn)) { |
3659 | err = PTR_ERR(kn); | |
0ab02ca8 | 3660 | goto err_free_id; |
2bd59d48 TH |
3661 | } |
3662 | cgrp->kn = kn; | |
ddbcc7e8 | 3663 | |
6f30558f TH |
3664 | /* |
3665 | * This extra ref will be put in cgroup_free_fn() and guarantees | |
3666 | * that @cgrp->kn is always accessible. | |
3667 | */ | |
3668 | kernfs_get(kn); | |
3669 | ||
00356bd5 | 3670 | cgrp->serial_nr = cgroup_serial_nr_next++; |
53fa5261 | 3671 | |
4e139afc | 3672 | /* allocation complete, commit to creation */ |
4e139afc | 3673 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); |
3c9c825b | 3674 | atomic_inc(&root->nr_cgrps); |
59f5296b | 3675 | cgroup_get(parent); |
415cf07a | 3676 | |
0d80255e TH |
3677 | /* |
3678 | * @cgrp is now fully operational. If something fails after this | |
3679 | * point, it'll be released via the normal destruction path. | |
3680 | */ | |
4e96ee8e LZ |
3681 | idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
3682 | ||
2bb566cb | 3683 | err = cgroup_addrm_files(cgrp, cgroup_base_files, true); |
628f7cd4 TH |
3684 | if (err) |
3685 | goto err_destroy; | |
3686 | ||
9d403e99 | 3687 | /* let's create and online css's */ |
b85d2040 TH |
3688 | for_each_subsys(ss, ssid) { |
3689 | if (root->subsys_mask & (1 << ssid)) { | |
3690 | err = create_css(cgrp, ss); | |
3691 | if (err) | |
3692 | goto err_destroy; | |
3693 | } | |
a8638030 | 3694 | } |
ddbcc7e8 | 3695 | |
2bd59d48 TH |
3696 | kernfs_activate(kn); |
3697 | ||
ddbcc7e8 | 3698 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 3699 | mutex_unlock(&cgroup_tree_mutex); |
ddbcc7e8 PM |
3700 | |
3701 | return 0; | |
3702 | ||
0a950f65 | 3703 | err_free_id: |
4e96ee8e | 3704 | idr_remove(&root->cgroup_idr, cgrp->id); |
0ab02ca8 LZ |
3705 | err_unlock: |
3706 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 TH |
3707 | err_unlock_tree: |
3708 | mutex_unlock(&cgroup_tree_mutex); | |
bd89aabc | 3709 | kfree(cgrp); |
ddbcc7e8 | 3710 | return err; |
4b8b47eb TH |
3711 | |
3712 | err_destroy: | |
3713 | cgroup_destroy_locked(cgrp); | |
3714 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 3715 | mutex_unlock(&cgroup_tree_mutex); |
4b8b47eb | 3716 | return err; |
ddbcc7e8 PM |
3717 | } |
3718 | ||
2bd59d48 TH |
3719 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
3720 | umode_t mode) | |
ddbcc7e8 | 3721 | { |
2bd59d48 | 3722 | struct cgroup *parent = parent_kn->priv; |
ddbcc7e8 | 3723 | |
2bd59d48 | 3724 | return cgroup_create(parent, name, mode); |
ddbcc7e8 PM |
3725 | } |
3726 | ||
223dbc38 TH |
3727 | /* |
3728 | * This is called when the refcnt of a css is confirmed to be killed. | |
3729 | * css_tryget() is now guaranteed to fail. | |
3730 | */ | |
3731 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 3732 | { |
223dbc38 TH |
3733 | struct cgroup_subsys_state *css = |
3734 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
3735 | struct cgroup *cgrp = css->cgroup; | |
d3daf28d | 3736 | |
ace2bee8 | 3737 | mutex_lock(&cgroup_tree_mutex); |
f20104de TH |
3738 | mutex_lock(&cgroup_mutex); |
3739 | ||
09a503ea TH |
3740 | /* |
3741 | * css_tryget() is guaranteed to fail now. Tell subsystems to | |
3742 | * initate destruction. | |
3743 | */ | |
3744 | offline_css(css); | |
3745 | ||
f20104de TH |
3746 | /* |
3747 | * If @cgrp is marked dead, it's waiting for refs of all css's to | |
3748 | * be disabled before proceeding to the second phase of cgroup | |
3749 | * destruction. If we are the last one, kick it off. | |
3750 | */ | |
09a503ea | 3751 | if (!cgrp->nr_css && cgroup_is_dead(cgrp)) |
f20104de TH |
3752 | cgroup_destroy_css_killed(cgrp); |
3753 | ||
3754 | mutex_unlock(&cgroup_mutex); | |
ace2bee8 | 3755 | mutex_unlock(&cgroup_tree_mutex); |
09a503ea TH |
3756 | |
3757 | /* | |
3758 | * Put the css refs from kill_css(). Each css holds an extra | |
3759 | * reference to the cgroup's dentry and cgroup removal proceeds | |
3760 | * regardless of css refs. On the last put of each css, whenever | |
3761 | * that may be, the extra dentry ref is put so that dentry | |
3762 | * destruction happens only after all css's are released. | |
3763 | */ | |
3764 | css_put(css); | |
d3daf28d TH |
3765 | } |
3766 | ||
223dbc38 TH |
3767 | /* css kill confirmation processing requires process context, bounce */ |
3768 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
3769 | { |
3770 | struct cgroup_subsys_state *css = | |
3771 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
3772 | ||
223dbc38 | 3773 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 3774 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
3775 | } |
3776 | ||
edae0c33 TH |
3777 | /** |
3778 | * kill_css - destroy a css | |
3779 | * @css: css to destroy | |
3780 | * | |
3c14f8b4 TH |
3781 | * This function initiates destruction of @css by removing cgroup interface |
3782 | * files and putting its base reference. ->css_offline() will be invoked | |
3783 | * asynchronously once css_tryget() is guaranteed to fail and when the | |
3784 | * reference count reaches zero, @css will be released. | |
edae0c33 TH |
3785 | */ |
3786 | static void kill_css(struct cgroup_subsys_state *css) | |
3787 | { | |
2bd59d48 TH |
3788 | /* |
3789 | * This must happen before css is disassociated with its cgroup. | |
3790 | * See seq_css() for details. | |
3791 | */ | |
aec25020 | 3792 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3c14f8b4 | 3793 | |
edae0c33 TH |
3794 | /* |
3795 | * Killing would put the base ref, but we need to keep it alive | |
3796 | * until after ->css_offline(). | |
3797 | */ | |
3798 | css_get(css); | |
3799 | ||
3800 | /* | |
3801 | * cgroup core guarantees that, by the time ->css_offline() is | |
3802 | * invoked, no new css reference will be given out via | |
3803 | * css_tryget(). We can't simply call percpu_ref_kill() and | |
3804 | * proceed to offlining css's because percpu_ref_kill() doesn't | |
3805 | * guarantee that the ref is seen as killed on all CPUs on return. | |
3806 | * | |
3807 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
3808 | * css is confirmed to be seen as killed on all CPUs. | |
3809 | */ | |
3810 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
3811 | } |
3812 | ||
3813 | /** | |
3814 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
3815 | * @cgrp: cgroup to be destroyed | |
3816 | * | |
3817 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
3818 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
3819 | * guarantee that css_tryget() won't succeed by the time ->css_offline() is | |
3820 | * invoked. To satisfy all the requirements, destruction is implemented in | |
3821 | * the following two steps. | |
3822 | * | |
3823 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
3824 | * userland visible parts and start killing the percpu refcnts of | |
3825 | * css's. Set up so that the next stage will be kicked off once all | |
3826 | * the percpu refcnts are confirmed to be killed. | |
3827 | * | |
3828 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
3829 | * rest of destruction. Once all cgroup references are gone, the | |
3830 | * cgroup is RCU-freed. | |
3831 | * | |
3832 | * This function implements s1. After this step, @cgrp is gone as far as | |
3833 | * the userland is concerned and a new cgroup with the same name may be | |
3834 | * created. As cgroup doesn't care about the names internally, this | |
3835 | * doesn't cause any problem. | |
3836 | */ | |
42809dd4 TH |
3837 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
3838 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 3839 | { |
bb78a92f | 3840 | struct cgroup *child; |
2bd59d48 | 3841 | struct cgroup_subsys_state *css; |
ddd69148 | 3842 | bool empty; |
1c6727af | 3843 | int ssid; |
ddbcc7e8 | 3844 | |
ace2bee8 | 3845 | lockdep_assert_held(&cgroup_tree_mutex); |
42809dd4 TH |
3846 | lockdep_assert_held(&cgroup_mutex); |
3847 | ||
ddd69148 | 3848 | /* |
96d365e0 | 3849 | * css_set_rwsem synchronizes access to ->cset_links and prevents |
89c5509b | 3850 | * @cgrp from being removed while put_css_set() is in progress. |
ddd69148 | 3851 | */ |
96d365e0 | 3852 | down_read(&css_set_rwsem); |
bb78a92f | 3853 | empty = list_empty(&cgrp->cset_links); |
96d365e0 | 3854 | up_read(&css_set_rwsem); |
ddd69148 | 3855 | if (!empty) |
ddbcc7e8 | 3856 | return -EBUSY; |
a043e3b2 | 3857 | |
bb78a92f HD |
3858 | /* |
3859 | * Make sure there's no live children. We can't test ->children | |
3860 | * emptiness as dead children linger on it while being destroyed; | |
3861 | * otherwise, "rmdir parent/child parent" may fail with -EBUSY. | |
3862 | */ | |
3863 | empty = true; | |
3864 | rcu_read_lock(); | |
3865 | list_for_each_entry_rcu(child, &cgrp->children, sibling) { | |
3866 | empty = cgroup_is_dead(child); | |
3867 | if (!empty) | |
3868 | break; | |
3869 | } | |
3870 | rcu_read_unlock(); | |
3871 | if (!empty) | |
3872 | return -EBUSY; | |
3873 | ||
88703267 | 3874 | /* |
edae0c33 TH |
3875 | * Initiate massacre of all css's. cgroup_destroy_css_killed() |
3876 | * will be invoked to perform the rest of destruction once the | |
4ac06017 TH |
3877 | * percpu refs of all css's are confirmed to be killed. This |
3878 | * involves removing the subsystem's files, drop cgroup_mutex. | |
88703267 | 3879 | */ |
4ac06017 | 3880 | mutex_unlock(&cgroup_mutex); |
1c6727af TH |
3881 | for_each_css(css, ssid, cgrp) |
3882 | kill_css(css); | |
4ac06017 | 3883 | mutex_lock(&cgroup_mutex); |
455050d2 TH |
3884 | |
3885 | /* | |
3886 | * Mark @cgrp dead. This prevents further task migration and child | |
3887 | * creation by disabling cgroup_lock_live_group(). Note that | |
492eb21b | 3888 | * CGRP_DEAD assertion is depended upon by css_next_child() to |
455050d2 | 3889 | * resume iteration after dropping RCU read lock. See |
492eb21b | 3890 | * css_next_child() for details. |
455050d2 | 3891 | */ |
54766d4a | 3892 | set_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 | 3893 | |
455050d2 TH |
3894 | /* CGRP_DEAD is set, remove from ->release_list for the last time */ |
3895 | raw_spin_lock(&release_list_lock); | |
3896 | if (!list_empty(&cgrp->release_list)) | |
3897 | list_del_init(&cgrp->release_list); | |
3898 | raw_spin_unlock(&release_list_lock); | |
3899 | ||
3900 | /* | |
f20104de TH |
3901 | * If @cgrp has css's attached, the second stage of cgroup |
3902 | * destruction is kicked off from css_killed_work_fn() after the | |
3903 | * refs of all attached css's are killed. If @cgrp doesn't have | |
3904 | * any css, we kick it off here. | |
3905 | */ | |
3906 | if (!cgrp->nr_css) | |
3907 | cgroup_destroy_css_killed(cgrp); | |
3908 | ||
2bd59d48 TH |
3909 | /* remove @cgrp directory along with the base files */ |
3910 | mutex_unlock(&cgroup_mutex); | |
3911 | ||
455050d2 | 3912 | /* |
2bd59d48 TH |
3913 | * There are two control paths which try to determine cgroup from |
3914 | * dentry without going through kernfs - cgroupstats_build() and | |
3915 | * css_tryget_from_dir(). Those are supported by RCU protecting | |
3916 | * clearing of cgrp->kn->priv backpointer, which should happen | |
3917 | * after all files under it have been removed. | |
455050d2 | 3918 | */ |
6f30558f | 3919 | kernfs_remove(cgrp->kn); /* @cgrp has an extra ref on its kn */ |
2bd59d48 | 3920 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); |
2bd59d48 | 3921 | |
4ac06017 | 3922 | mutex_lock(&cgroup_mutex); |
455050d2 | 3923 | |
ea15f8cc TH |
3924 | return 0; |
3925 | }; | |
3926 | ||
d3daf28d | 3927 | /** |
f20104de | 3928 | * cgroup_destroy_css_killed - the second step of cgroup destruction |
d3daf28d TH |
3929 | * @work: cgroup->destroy_free_work |
3930 | * | |
3931 | * This function is invoked from a work item for a cgroup which is being | |
09a503ea TH |
3932 | * destroyed after all css's are offlined and performs the rest of |
3933 | * destruction. This is the second step of destruction described in the | |
3934 | * comment above cgroup_destroy_locked(). | |
d3daf28d | 3935 | */ |
f20104de | 3936 | static void cgroup_destroy_css_killed(struct cgroup *cgrp) |
ea15f8cc | 3937 | { |
ea15f8cc | 3938 | struct cgroup *parent = cgrp->parent; |
ea15f8cc | 3939 | |
ace2bee8 | 3940 | lockdep_assert_held(&cgroup_tree_mutex); |
f20104de | 3941 | lockdep_assert_held(&cgroup_mutex); |
ea15f8cc | 3942 | |
999cd8a4 | 3943 | /* delete this cgroup from parent->children */ |
eb6fd504 | 3944 | list_del_rcu(&cgrp->sibling); |
ed957793 | 3945 | |
59f5296b | 3946 | cgroup_put(cgrp); |
ddbcc7e8 | 3947 | |
bd89aabc | 3948 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd | 3949 | check_for_release(parent); |
ddbcc7e8 PM |
3950 | } |
3951 | ||
2bd59d48 | 3952 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 3953 | { |
2bd59d48 TH |
3954 | struct cgroup *cgrp = kn->priv; |
3955 | int ret = 0; | |
3956 | ||
3957 | /* | |
3958 | * This is self-destruction but @kn can't be removed while this | |
3959 | * callback is in progress. Let's break active protection. Once | |
3960 | * the protection is broken, @cgrp can be destroyed at any point. | |
3961 | * Pin it so that it stays accessible. | |
3962 | */ | |
3963 | cgroup_get(cgrp); | |
3964 | kernfs_break_active_protection(kn); | |
42809dd4 | 3965 | |
ace2bee8 | 3966 | mutex_lock(&cgroup_tree_mutex); |
42809dd4 | 3967 | mutex_lock(&cgroup_mutex); |
2bd59d48 TH |
3968 | |
3969 | /* | |
3970 | * @cgrp might already have been destroyed while we're trying to | |
3971 | * grab the mutexes. | |
3972 | */ | |
3973 | if (!cgroup_is_dead(cgrp)) | |
3974 | ret = cgroup_destroy_locked(cgrp); | |
3975 | ||
42809dd4 | 3976 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 3977 | mutex_unlock(&cgroup_tree_mutex); |
42809dd4 | 3978 | |
2bd59d48 TH |
3979 | kernfs_unbreak_active_protection(kn); |
3980 | cgroup_put(cgrp); | |
42809dd4 TH |
3981 | return ret; |
3982 | } | |
3983 | ||
2bd59d48 TH |
3984 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
3985 | .remount_fs = cgroup_remount, | |
3986 | .show_options = cgroup_show_options, | |
3987 | .mkdir = cgroup_mkdir, | |
3988 | .rmdir = cgroup_rmdir, | |
3989 | .rename = cgroup_rename, | |
3990 | }; | |
3991 | ||
06a11920 | 3992 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 3993 | { |
ddbcc7e8 | 3994 | struct cgroup_subsys_state *css; |
cfe36bde DC |
3995 | |
3996 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 3997 | |
ace2bee8 | 3998 | mutex_lock(&cgroup_tree_mutex); |
648bb56d TH |
3999 | mutex_lock(&cgroup_mutex); |
4000 | ||
0adb0704 | 4001 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 4002 | |
ddbcc7e8 | 4003 | /* Create the top cgroup state for this subsystem */ |
9871bf95 | 4004 | ss->root = &cgroup_dummy_root; |
ca8bdcaf | 4005 | css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss)); |
ddbcc7e8 PM |
4006 | /* We don't handle early failures gracefully */ |
4007 | BUG_ON(IS_ERR(css)); | |
623f926b | 4008 | init_css(css, ss, cgroup_dummy_top); |
ddbcc7e8 | 4009 | |
e8d55fde | 4010 | /* Update the init_css_set to contain a subsys |
817929ec | 4011 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
4012 | * newly registered, all tasks and hence the |
4013 | * init_css_set is in the subsystem's top cgroup. */ | |
aec25020 | 4014 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 PM |
4015 | |
4016 | need_forkexit_callback |= ss->fork || ss->exit; | |
4017 | ||
e8d55fde LZ |
4018 | /* At system boot, before all subsystems have been |
4019 | * registered, no tasks have been forked, so we don't | |
4020 | * need to invoke fork callbacks here. */ | |
4021 | BUG_ON(!list_empty(&init_task.tasks)); | |
4022 | ||
ae7f164a | 4023 | BUG_ON(online_css(css)); |
a8638030 | 4024 | |
648bb56d | 4025 | mutex_unlock(&cgroup_mutex); |
ace2bee8 | 4026 | mutex_unlock(&cgroup_tree_mutex); |
e6a1105b BB |
4027 | } |
4028 | ||
ddbcc7e8 | 4029 | /** |
a043e3b2 LZ |
4030 | * cgroup_init_early - cgroup initialization at system boot |
4031 | * | |
4032 | * Initialize cgroups at system boot, and initialize any | |
4033 | * subsystems that request early init. | |
ddbcc7e8 PM |
4034 | */ |
4035 | int __init cgroup_init_early(void) | |
4036 | { | |
30159ec7 | 4037 | struct cgroup_subsys *ss; |
ddbcc7e8 | 4038 | int i; |
30159ec7 | 4039 | |
146aa1bd | 4040 | atomic_set(&init_css_set.refcount, 1); |
69d0206c | 4041 | INIT_LIST_HEAD(&init_css_set.cgrp_links); |
817929ec | 4042 | INIT_LIST_HEAD(&init_css_set.tasks); |
b3dc094e | 4043 | INIT_LIST_HEAD(&init_css_set.mg_tasks); |
1958d2d5 | 4044 | INIT_LIST_HEAD(&init_css_set.mg_preload_node); |
b3dc094e | 4045 | INIT_LIST_HEAD(&init_css_set.mg_node); |
472b1053 | 4046 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 4047 | css_set_count = 1; |
9871bf95 TH |
4048 | init_cgroup_root(&cgroup_dummy_root); |
4049 | cgroup_root_count = 1; | |
a4ea1cc9 | 4050 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 4051 | |
69d0206c | 4052 | init_cgrp_cset_link.cset = &init_css_set; |
9871bf95 TH |
4053 | init_cgrp_cset_link.cgrp = cgroup_dummy_top; |
4054 | list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links); | |
69d0206c | 4055 | list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links); |
ddbcc7e8 | 4056 | |
3ed80a62 | 4057 | for_each_subsys(ss, i) { |
aec25020 | 4058 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
4059 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
4060 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 4061 | ss->id, ss->name); |
073219e9 TH |
4062 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
4063 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
4064 | ||
aec25020 | 4065 | ss->id = i; |
073219e9 | 4066 | ss->name = cgroup_subsys_name[i]; |
ddbcc7e8 PM |
4067 | |
4068 | if (ss->early_init) | |
4069 | cgroup_init_subsys(ss); | |
4070 | } | |
4071 | return 0; | |
4072 | } | |
4073 | ||
4074 | /** | |
a043e3b2 LZ |
4075 | * cgroup_init - cgroup initialization |
4076 | * | |
4077 | * Register cgroup filesystem and /proc file, and initialize | |
4078 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4079 | */ |
4080 | int __init cgroup_init(void) | |
4081 | { | |
30159ec7 | 4082 | struct cgroup_subsys *ss; |
0ac801fe | 4083 | unsigned long key; |
30159ec7 | 4084 | int i, err; |
a424316c | 4085 | |
2bd59d48 | 4086 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files)); |
2da440a2 | 4087 | |
3ed80a62 | 4088 | for_each_subsys(ss, i) { |
ddbcc7e8 PM |
4089 | if (!ss->early_init) |
4090 | cgroup_init_subsys(ss); | |
de00ffa5 TH |
4091 | |
4092 | /* | |
4093 | * cftype registration needs kmalloc and can't be done | |
4094 | * during early_init. Register base cftypes separately. | |
4095 | */ | |
4096 | if (ss->base_cftypes) | |
4097 | WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes)); | |
ddbcc7e8 PM |
4098 | } |
4099 | ||
fa3ca07e | 4100 | /* allocate id for the dummy hierarchy */ |
54e7b4eb | 4101 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 4102 | |
82fe9b0d TH |
4103 | /* Add init_css_set to the hash table */ |
4104 | key = css_set_hash(init_css_set.subsys); | |
4105 | hash_add(css_set_table, &init_css_set.hlist, key); | |
4106 | ||
fc76df70 | 4107 | BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1)); |
676db4af | 4108 | |
4e96ee8e LZ |
4109 | err = idr_alloc(&cgroup_dummy_root.cgroup_idr, cgroup_dummy_top, |
4110 | 0, 1, GFP_KERNEL); | |
4111 | BUG_ON(err < 0); | |
4112 | ||
54e7b4eb TH |
4113 | mutex_unlock(&cgroup_mutex); |
4114 | ||
676db4af | 4115 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
2bd59d48 TH |
4116 | if (!cgroup_kobj) |
4117 | return -ENOMEM; | |
676db4af | 4118 | |
ddbcc7e8 | 4119 | err = register_filesystem(&cgroup_fs_type); |
676db4af GK |
4120 | if (err < 0) { |
4121 | kobject_put(cgroup_kobj); | |
2bd59d48 | 4122 | return err; |
676db4af | 4123 | } |
ddbcc7e8 | 4124 | |
46ae220b | 4125 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 4126 | return 0; |
ddbcc7e8 | 4127 | } |
b4f48b63 | 4128 | |
e5fca243 TH |
4129 | static int __init cgroup_wq_init(void) |
4130 | { | |
4131 | /* | |
4132 | * There isn't much point in executing destruction path in | |
4133 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 4134 | * Use 1 for @max_active. |
e5fca243 TH |
4135 | * |
4136 | * We would prefer to do this in cgroup_init() above, but that | |
4137 | * is called before init_workqueues(): so leave this until after. | |
4138 | */ | |
1a11533f | 4139 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 4140 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
4141 | |
4142 | /* | |
4143 | * Used to destroy pidlists and separate to serve as flush domain. | |
4144 | * Cap @max_active to 1 too. | |
4145 | */ | |
4146 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
4147 | 0, 1); | |
4148 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
4149 | ||
e5fca243 TH |
4150 | return 0; |
4151 | } | |
4152 | core_initcall(cgroup_wq_init); | |
4153 | ||
a424316c PM |
4154 | /* |
4155 | * proc_cgroup_show() | |
4156 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4157 | * - Used for /proc/<pid>/cgroup. | |
4158 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4159 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 4160 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
4161 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4162 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4163 | * cgroup to top_cgroup. | |
4164 | */ | |
4165 | ||
4166 | /* TODO: Use a proper seq_file iterator */ | |
8d8b97ba | 4167 | int proc_cgroup_show(struct seq_file *m, void *v) |
a424316c PM |
4168 | { |
4169 | struct pid *pid; | |
4170 | struct task_struct *tsk; | |
e61734c5 | 4171 | char *buf, *path; |
a424316c PM |
4172 | int retval; |
4173 | struct cgroupfs_root *root; | |
4174 | ||
4175 | retval = -ENOMEM; | |
e61734c5 | 4176 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
4177 | if (!buf) |
4178 | goto out; | |
4179 | ||
4180 | retval = -ESRCH; | |
4181 | pid = m->private; | |
4182 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4183 | if (!tsk) | |
4184 | goto out_free; | |
4185 | ||
4186 | retval = 0; | |
4187 | ||
4188 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 4189 | down_read(&css_set_rwsem); |
a424316c | 4190 | |
e5f6a860 | 4191 | for_each_active_root(root) { |
a424316c | 4192 | struct cgroup_subsys *ss; |
bd89aabc | 4193 | struct cgroup *cgrp; |
b85d2040 | 4194 | int ssid, count = 0; |
a424316c | 4195 | |
2c6ab6d2 | 4196 | seq_printf(m, "%d:", root->hierarchy_id); |
b85d2040 TH |
4197 | for_each_subsys(ss, ssid) |
4198 | if (root->subsys_mask & (1 << ssid)) | |
4199 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
c6d57f33 PM |
4200 | if (strlen(root->name)) |
4201 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4202 | root->name); | |
a424316c | 4203 | seq_putc(m, ':'); |
7717f7ba | 4204 | cgrp = task_cgroup_from_root(tsk, root); |
e61734c5 TH |
4205 | path = cgroup_path(cgrp, buf, PATH_MAX); |
4206 | if (!path) { | |
4207 | retval = -ENAMETOOLONG; | |
a424316c | 4208 | goto out_unlock; |
e61734c5 TH |
4209 | } |
4210 | seq_puts(m, path); | |
a424316c PM |
4211 | seq_putc(m, '\n'); |
4212 | } | |
4213 | ||
4214 | out_unlock: | |
96d365e0 | 4215 | up_read(&css_set_rwsem); |
a424316c PM |
4216 | mutex_unlock(&cgroup_mutex); |
4217 | put_task_struct(tsk); | |
4218 | out_free: | |
4219 | kfree(buf); | |
4220 | out: | |
4221 | return retval; | |
4222 | } | |
4223 | ||
a424316c PM |
4224 | /* Display information about each subsystem and each hierarchy */ |
4225 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4226 | { | |
30159ec7 | 4227 | struct cgroup_subsys *ss; |
a424316c | 4228 | int i; |
a424316c | 4229 | |
8bab8dde | 4230 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4231 | /* |
4232 | * ideally we don't want subsystems moving around while we do this. | |
4233 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4234 | * subsys/hierarchy state. | |
4235 | */ | |
a424316c | 4236 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
4237 | |
4238 | for_each_subsys(ss, i) | |
2c6ab6d2 PM |
4239 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4240 | ss->name, ss->root->hierarchy_id, | |
3c9c825b | 4241 | atomic_read(&ss->root->nr_cgrps), !ss->disabled); |
30159ec7 | 4242 | |
a424316c PM |
4243 | mutex_unlock(&cgroup_mutex); |
4244 | return 0; | |
4245 | } | |
4246 | ||
4247 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4248 | { | |
9dce07f1 | 4249 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4250 | } |
4251 | ||
828c0950 | 4252 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4253 | .open = cgroupstats_open, |
4254 | .read = seq_read, | |
4255 | .llseek = seq_lseek, | |
4256 | .release = single_release, | |
4257 | }; | |
4258 | ||
b4f48b63 | 4259 | /** |
eaf797ab | 4260 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 4261 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 4262 | * |
eaf797ab TH |
4263 | * A task is associated with the init_css_set until cgroup_post_fork() |
4264 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
4265 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
4266 | */ |
4267 | void cgroup_fork(struct task_struct *child) | |
4268 | { | |
eaf797ab | 4269 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 4270 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
4271 | } |
4272 | ||
817929ec | 4273 | /** |
a043e3b2 LZ |
4274 | * cgroup_post_fork - called on a new task after adding it to the task list |
4275 | * @child: the task in question | |
4276 | * | |
5edee61e TH |
4277 | * Adds the task to the list running through its css_set if necessary and |
4278 | * call the subsystem fork() callbacks. Has to be after the task is | |
4279 | * visible on the task list in case we race with the first call to | |
0942eeee | 4280 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 4281 | * list. |
a043e3b2 | 4282 | */ |
817929ec PM |
4283 | void cgroup_post_fork(struct task_struct *child) |
4284 | { | |
30159ec7 | 4285 | struct cgroup_subsys *ss; |
5edee61e TH |
4286 | int i; |
4287 | ||
3ce3230a | 4288 | /* |
eaf797ab TH |
4289 | * This may race against cgroup_enable_task_cg_links(). As that |
4290 | * function sets use_task_css_set_links before grabbing | |
4291 | * tasklist_lock and we just went through tasklist_lock to add | |
4292 | * @child, it's guaranteed that either we see the set | |
4293 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
4294 | * @child during its iteration. | |
4295 | * | |
4296 | * If we won the race, @child is associated with %current's | |
4297 | * css_set. Grabbing css_set_rwsem guarantees both that the | |
4298 | * association is stable, and, on completion of the parent's | |
4299 | * migration, @child is visible in the source of migration or | |
4300 | * already in the destination cgroup. This guarantee is necessary | |
4301 | * when implementing operations which need to migrate all tasks of | |
4302 | * a cgroup to another. | |
4303 | * | |
4304 | * Note that if we lose to cgroup_enable_task_cg_links(), @child | |
4305 | * will remain in init_css_set. This is safe because all tasks are | |
4306 | * in the init_css_set before cg_links is enabled and there's no | |
4307 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 4308 | */ |
817929ec | 4309 | if (use_task_css_set_links) { |
eaf797ab TH |
4310 | struct css_set *cset; |
4311 | ||
96d365e0 | 4312 | down_write(&css_set_rwsem); |
eaf797ab TH |
4313 | cset = task_css_set_check(current, |
4314 | lockdep_is_held(&css_set_rwsem)); | |
d8783832 | 4315 | task_lock(child); |
eaf797ab TH |
4316 | if (list_empty(&child->cg_list)) { |
4317 | rcu_assign_pointer(child->cgroups, cset); | |
4318 | list_add(&child->cg_list, &cset->tasks); | |
4319 | get_css_set(cset); | |
4320 | } | |
d8783832 | 4321 | task_unlock(child); |
96d365e0 | 4322 | up_write(&css_set_rwsem); |
817929ec | 4323 | } |
5edee61e TH |
4324 | |
4325 | /* | |
4326 | * Call ss->fork(). This must happen after @child is linked on | |
4327 | * css_set; otherwise, @child might change state between ->fork() | |
4328 | * and addition to css_set. | |
4329 | */ | |
4330 | if (need_forkexit_callback) { | |
3ed80a62 | 4331 | for_each_subsys(ss, i) |
5edee61e TH |
4332 | if (ss->fork) |
4333 | ss->fork(child); | |
5edee61e | 4334 | } |
817929ec | 4335 | } |
5edee61e | 4336 | |
b4f48b63 PM |
4337 | /** |
4338 | * cgroup_exit - detach cgroup from exiting task | |
4339 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 4340 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
4341 | * |
4342 | * Description: Detach cgroup from @tsk and release it. | |
4343 | * | |
4344 | * Note that cgroups marked notify_on_release force every task in | |
4345 | * them to take the global cgroup_mutex mutex when exiting. | |
4346 | * This could impact scaling on very large systems. Be reluctant to | |
4347 | * use notify_on_release cgroups where very high task exit scaling | |
4348 | * is required on large systems. | |
4349 | * | |
4350 | * the_top_cgroup_hack: | |
4351 | * | |
4352 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
4353 | * | |
4354 | * We call cgroup_exit() while the task is still competent to | |
4355 | * handle notify_on_release(), then leave the task attached to the | |
4356 | * root cgroup in each hierarchy for the remainder of its exit. | |
4357 | * | |
4358 | * To do this properly, we would increment the reference count on | |
4359 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
4360 | * code we would add a second cgroup function call, to drop that | |
4361 | * reference. This would just create an unnecessary hot spot on | |
4362 | * the top_cgroup reference count, to no avail. | |
4363 | * | |
4364 | * Normally, holding a reference to a cgroup without bumping its | |
4365 | * count is unsafe. The cgroup could go away, or someone could | |
4366 | * attach us to a different cgroup, decrementing the count on | |
4367 | * the first cgroup that we never incremented. But in this case, | |
4368 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
4369 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
4370 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
4371 | */ |
4372 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
4373 | { | |
30159ec7 | 4374 | struct cgroup_subsys *ss; |
5abb8855 | 4375 | struct css_set *cset; |
eaf797ab | 4376 | bool put_cset = false; |
d41d5a01 | 4377 | int i; |
817929ec PM |
4378 | |
4379 | /* | |
96d365e0 TH |
4380 | * Unlink from the css_set task list if necessary. Optimistically |
4381 | * check cg_list before taking css_set_rwsem. | |
817929ec PM |
4382 | */ |
4383 | if (!list_empty(&tsk->cg_list)) { | |
96d365e0 | 4384 | down_write(&css_set_rwsem); |
eaf797ab | 4385 | if (!list_empty(&tsk->cg_list)) { |
8d258797 | 4386 | list_del_init(&tsk->cg_list); |
eaf797ab TH |
4387 | put_cset = true; |
4388 | } | |
96d365e0 | 4389 | up_write(&css_set_rwsem); |
817929ec PM |
4390 | } |
4391 | ||
b4f48b63 PM |
4392 | /* Reassign the task to the init_css_set. */ |
4393 | task_lock(tsk); | |
a8ad805c TH |
4394 | cset = task_css_set(tsk); |
4395 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 PZ |
4396 | |
4397 | if (run_callbacks && need_forkexit_callback) { | |
3ed80a62 TH |
4398 | /* see cgroup_post_fork() for details */ |
4399 | for_each_subsys(ss, i) { | |
d41d5a01 | 4400 | if (ss->exit) { |
eb95419b TH |
4401 | struct cgroup_subsys_state *old_css = cset->subsys[i]; |
4402 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 4403 | |
eb95419b | 4404 | ss->exit(css, old_css, tsk); |
d41d5a01 PZ |
4405 | } |
4406 | } | |
4407 | } | |
b4f48b63 | 4408 | task_unlock(tsk); |
d41d5a01 | 4409 | |
eaf797ab TH |
4410 | if (put_cset) |
4411 | put_css_set(cset, true); | |
b4f48b63 | 4412 | } |
697f4161 | 4413 | |
bd89aabc | 4414 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 4415 | { |
f50daa70 | 4416 | if (cgroup_is_releasable(cgrp) && |
6f3d828f | 4417 | list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { |
f50daa70 LZ |
4418 | /* |
4419 | * Control Group is currently removeable. If it's not | |
81a6a5cd | 4420 | * already queued for a userspace notification, queue |
f50daa70 LZ |
4421 | * it now |
4422 | */ | |
81a6a5cd | 4423 | int need_schedule_work = 0; |
f50daa70 | 4424 | |
cdcc136f | 4425 | raw_spin_lock(&release_list_lock); |
54766d4a | 4426 | if (!cgroup_is_dead(cgrp) && |
bd89aabc PM |
4427 | list_empty(&cgrp->release_list)) { |
4428 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4429 | need_schedule_work = 1; |
4430 | } | |
cdcc136f | 4431 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4432 | if (need_schedule_work) |
4433 | schedule_work(&release_agent_work); | |
4434 | } | |
4435 | } | |
4436 | ||
81a6a5cd PM |
4437 | /* |
4438 | * Notify userspace when a cgroup is released, by running the | |
4439 | * configured release agent with the name of the cgroup (path | |
4440 | * relative to the root of cgroup file system) as the argument. | |
4441 | * | |
4442 | * Most likely, this user command will try to rmdir this cgroup. | |
4443 | * | |
4444 | * This races with the possibility that some other task will be | |
4445 | * attached to this cgroup before it is removed, or that some other | |
4446 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
4447 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
4448 | * unused, and this cgroup will be reprieved from its death sentence, | |
4449 | * to continue to serve a useful existence. Next time it's released, | |
4450 | * we will get notified again, if it still has 'notify_on_release' set. | |
4451 | * | |
4452 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
4453 | * means only wait until the task is successfully execve()'d. The | |
4454 | * separate release agent task is forked by call_usermodehelper(), | |
4455 | * then control in this thread returns here, without waiting for the | |
4456 | * release agent task. We don't bother to wait because the caller of | |
4457 | * this routine has no use for the exit status of the release agent | |
4458 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 4459 | */ |
81a6a5cd PM |
4460 | static void cgroup_release_agent(struct work_struct *work) |
4461 | { | |
4462 | BUG_ON(work != &release_agent_work); | |
4463 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 4464 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
4465 | while (!list_empty(&release_list)) { |
4466 | char *argv[3], *envp[3]; | |
4467 | int i; | |
e61734c5 | 4468 | char *pathbuf = NULL, *agentbuf = NULL, *path; |
bd89aabc | 4469 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
4470 | struct cgroup, |
4471 | release_list); | |
bd89aabc | 4472 | list_del_init(&cgrp->release_list); |
cdcc136f | 4473 | raw_spin_unlock(&release_list_lock); |
e61734c5 | 4474 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
e788e066 PM |
4475 | if (!pathbuf) |
4476 | goto continue_free; | |
e61734c5 TH |
4477 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); |
4478 | if (!path) | |
e788e066 PM |
4479 | goto continue_free; |
4480 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
4481 | if (!agentbuf) | |
4482 | goto continue_free; | |
81a6a5cd PM |
4483 | |
4484 | i = 0; | |
e788e066 | 4485 | argv[i++] = agentbuf; |
e61734c5 | 4486 | argv[i++] = path; |
81a6a5cd PM |
4487 | argv[i] = NULL; |
4488 | ||
4489 | i = 0; | |
4490 | /* minimal command environment */ | |
4491 | envp[i++] = "HOME=/"; | |
4492 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
4493 | envp[i] = NULL; | |
4494 | ||
4495 | /* Drop the lock while we invoke the usermode helper, | |
4496 | * since the exec could involve hitting disk and hence | |
4497 | * be a slow process */ | |
4498 | mutex_unlock(&cgroup_mutex); | |
4499 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 4500 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
4501 | continue_free: |
4502 | kfree(pathbuf); | |
4503 | kfree(agentbuf); | |
cdcc136f | 4504 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 4505 | } |
cdcc136f | 4506 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4507 | mutex_unlock(&cgroup_mutex); |
4508 | } | |
8bab8dde PM |
4509 | |
4510 | static int __init cgroup_disable(char *str) | |
4511 | { | |
30159ec7 | 4512 | struct cgroup_subsys *ss; |
8bab8dde | 4513 | char *token; |
30159ec7 | 4514 | int i; |
8bab8dde PM |
4515 | |
4516 | while ((token = strsep(&str, ",")) != NULL) { | |
4517 | if (!*token) | |
4518 | continue; | |
be45c900 | 4519 | |
3ed80a62 | 4520 | for_each_subsys(ss, i) { |
8bab8dde PM |
4521 | if (!strcmp(token, ss->name)) { |
4522 | ss->disabled = 1; | |
4523 | printk(KERN_INFO "Disabling %s control group" | |
4524 | " subsystem\n", ss->name); | |
4525 | break; | |
4526 | } | |
4527 | } | |
4528 | } | |
4529 | return 1; | |
4530 | } | |
4531 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 4532 | |
b77d7b60 | 4533 | /** |
5a17f543 | 4534 | * css_tryget_from_dir - get corresponding css from the dentry of a cgroup dir |
35cf0836 TH |
4535 | * @dentry: directory dentry of interest |
4536 | * @ss: subsystem of interest | |
b77d7b60 | 4537 | * |
5a17f543 TH |
4538 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
4539 | * to get the corresponding css and return it. If such css doesn't exist | |
4540 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 4541 | */ |
5a17f543 TH |
4542 | struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, |
4543 | struct cgroup_subsys *ss) | |
e5d1367f | 4544 | { |
2bd59d48 TH |
4545 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
4546 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 4547 | struct cgroup *cgrp; |
b77d7b60 | 4548 | |
35cf0836 | 4549 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
4550 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
4551 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
4552 | return ERR_PTR(-EBADF); |
4553 | ||
5a17f543 TH |
4554 | rcu_read_lock(); |
4555 | ||
2bd59d48 TH |
4556 | /* |
4557 | * This path doesn't originate from kernfs and @kn could already | |
4558 | * have been or be removed at any point. @kn->priv is RCU | |
4559 | * protected for this access. See destroy_locked() for details. | |
4560 | */ | |
4561 | cgrp = rcu_dereference(kn->priv); | |
4562 | if (cgrp) | |
4563 | css = cgroup_css(cgrp, ss); | |
5a17f543 TH |
4564 | |
4565 | if (!css || !css_tryget(css)) | |
4566 | css = ERR_PTR(-ENOENT); | |
4567 | ||
4568 | rcu_read_unlock(); | |
4569 | return css; | |
e5d1367f | 4570 | } |
e5d1367f | 4571 | |
1cb650b9 LZ |
4572 | /** |
4573 | * css_from_id - lookup css by id | |
4574 | * @id: the cgroup id | |
4575 | * @ss: cgroup subsys to be looked into | |
4576 | * | |
4577 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
4578 | * Should be called under rcu_read_lock(). | |
4579 | */ | |
4580 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
4581 | { | |
4582 | struct cgroup *cgrp; | |
4583 | ||
ace2bee8 | 4584 | cgroup_assert_mutexes_or_rcu_locked(); |
1cb650b9 LZ |
4585 | |
4586 | cgrp = idr_find(&ss->root->cgroup_idr, id); | |
4587 | if (cgrp) | |
d1625964 | 4588 | return cgroup_css(cgrp, ss); |
1cb650b9 | 4589 | return NULL; |
e5d1367f SE |
4590 | } |
4591 | ||
fe693435 | 4592 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
4593 | static struct cgroup_subsys_state * |
4594 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
4595 | { |
4596 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
4597 | ||
4598 | if (!css) | |
4599 | return ERR_PTR(-ENOMEM); | |
4600 | ||
4601 | return css; | |
4602 | } | |
4603 | ||
eb95419b | 4604 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 4605 | { |
eb95419b | 4606 | kfree(css); |
fe693435 PM |
4607 | } |
4608 | ||
182446d0 TH |
4609 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
4610 | struct cftype *cft) | |
fe693435 | 4611 | { |
182446d0 | 4612 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
4613 | } |
4614 | ||
182446d0 TH |
4615 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
4616 | struct cftype *cft) | |
fe693435 PM |
4617 | { |
4618 | return (u64)(unsigned long)current->cgroups; | |
4619 | } | |
4620 | ||
182446d0 | 4621 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 4622 | struct cftype *cft) |
fe693435 PM |
4623 | { |
4624 | u64 count; | |
4625 | ||
4626 | rcu_read_lock(); | |
a8ad805c | 4627 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
4628 | rcu_read_unlock(); |
4629 | return count; | |
4630 | } | |
4631 | ||
2da8ca82 | 4632 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 4633 | { |
69d0206c | 4634 | struct cgrp_cset_link *link; |
5abb8855 | 4635 | struct css_set *cset; |
e61734c5 TH |
4636 | char *name_buf; |
4637 | ||
4638 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
4639 | if (!name_buf) | |
4640 | return -ENOMEM; | |
7717f7ba | 4641 | |
96d365e0 | 4642 | down_read(&css_set_rwsem); |
7717f7ba | 4643 | rcu_read_lock(); |
5abb8855 | 4644 | cset = rcu_dereference(current->cgroups); |
69d0206c | 4645 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 4646 | struct cgroup *c = link->cgrp; |
59f5296b TH |
4647 | const char *name = "?"; |
4648 | ||
e61734c5 TH |
4649 | if (c != cgroup_dummy_top) { |
4650 | cgroup_name(c, name_buf, NAME_MAX + 1); | |
4651 | name = name_buf; | |
4652 | } | |
7717f7ba | 4653 | |
2c6ab6d2 PM |
4654 | seq_printf(seq, "Root %d group %s\n", |
4655 | c->root->hierarchy_id, name); | |
7717f7ba PM |
4656 | } |
4657 | rcu_read_unlock(); | |
96d365e0 | 4658 | up_read(&css_set_rwsem); |
e61734c5 | 4659 | kfree(name_buf); |
7717f7ba PM |
4660 | return 0; |
4661 | } | |
4662 | ||
4663 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 4664 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 4665 | { |
2da8ca82 | 4666 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 4667 | struct cgrp_cset_link *link; |
7717f7ba | 4668 | |
96d365e0 | 4669 | down_read(&css_set_rwsem); |
182446d0 | 4670 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 4671 | struct css_set *cset = link->cset; |
7717f7ba PM |
4672 | struct task_struct *task; |
4673 | int count = 0; | |
c7561128 | 4674 | |
5abb8855 | 4675 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 4676 | |
5abb8855 | 4677 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
4678 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
4679 | goto overflow; | |
4680 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
4681 | } | |
4682 | ||
4683 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
4684 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
4685 | goto overflow; | |
4686 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 4687 | } |
c7561128 TH |
4688 | continue; |
4689 | overflow: | |
4690 | seq_puts(seq, " ...\n"); | |
7717f7ba | 4691 | } |
96d365e0 | 4692 | up_read(&css_set_rwsem); |
7717f7ba PM |
4693 | return 0; |
4694 | } | |
4695 | ||
182446d0 | 4696 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 4697 | { |
182446d0 | 4698 | return test_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
fe693435 PM |
4699 | } |
4700 | ||
4701 | static struct cftype debug_files[] = { | |
fe693435 PM |
4702 | { |
4703 | .name = "taskcount", | |
4704 | .read_u64 = debug_taskcount_read, | |
4705 | }, | |
4706 | ||
4707 | { | |
4708 | .name = "current_css_set", | |
4709 | .read_u64 = current_css_set_read, | |
4710 | }, | |
4711 | ||
4712 | { | |
4713 | .name = "current_css_set_refcount", | |
4714 | .read_u64 = current_css_set_refcount_read, | |
4715 | }, | |
4716 | ||
7717f7ba PM |
4717 | { |
4718 | .name = "current_css_set_cg_links", | |
2da8ca82 | 4719 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
4720 | }, |
4721 | ||
4722 | { | |
4723 | .name = "cgroup_css_links", | |
2da8ca82 | 4724 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
4725 | }, |
4726 | ||
fe693435 PM |
4727 | { |
4728 | .name = "releasable", | |
4729 | .read_u64 = releasable_read, | |
4730 | }, | |
fe693435 | 4731 | |
4baf6e33 TH |
4732 | { } /* terminate */ |
4733 | }; | |
fe693435 | 4734 | |
073219e9 | 4735 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
4736 | .css_alloc = debug_css_alloc, |
4737 | .css_free = debug_css_free, | |
4baf6e33 | 4738 | .base_cftypes = debug_files, |
fe693435 PM |
4739 | }; |
4740 | #endif /* CONFIG_CGROUP_DEBUG */ |