Commit | Line | Data |
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ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
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> | |
817929ec | 43 | #include <linux/backing-dev.h> |
ddbcc7e8 PM |
44 | #include <linux/seq_file.h> |
45 | #include <linux/slab.h> | |
46 | #include <linux/magic.h> | |
47 | #include <linux/spinlock.h> | |
48 | #include <linux/string.h> | |
bbcb81d0 | 49 | #include <linux/sort.h> |
81a6a5cd | 50 | #include <linux/kmod.h> |
e6a1105b | 51 | #include <linux/module.h> |
846c7bb0 BS |
52 | #include <linux/delayacct.h> |
53 | #include <linux/cgroupstats.h> | |
0ac801fe | 54 | #include <linux/hashtable.h> |
3f8206d4 | 55 | #include <linux/namei.h> |
096b7fe0 | 56 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 57 | #include <linux/idr.h> |
d1d9fd33 | 58 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
0dea1168 KS |
59 | #include <linux/eventfd.h> |
60 | #include <linux/poll.h> | |
081aa458 | 61 | #include <linux/flex_array.h> /* used in cgroup_attach_task */ |
c4c27fbd | 62 | #include <linux/kthread.h> |
846c7bb0 | 63 | |
60063497 | 64 | #include <linux/atomic.h> |
ddbcc7e8 | 65 | |
e25e2cbb TH |
66 | /* |
67 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
68 | * hierarchy must be performed while holding it. | |
69 | * | |
70 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify | |
71 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags, | |
72 | * release_agent_path and so on. Modifying requires both cgroup_mutex and | |
73 | * cgroup_root_mutex. Readers can acquire either of the two. This is to | |
74 | * break the following locking order cycle. | |
75 | * | |
76 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem | |
77 | * B. namespace_sem -> cgroup_mutex | |
78 | * | |
79 | * B happens only through cgroup_show_options() and using cgroup_root_mutex | |
80 | * breaks it. | |
81 | */ | |
2219449a TH |
82 | #ifdef CONFIG_PROVE_RCU |
83 | DEFINE_MUTEX(cgroup_mutex); | |
8af01f56 | 84 | EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for lockdep */ |
2219449a | 85 | #else |
81a6a5cd | 86 | static DEFINE_MUTEX(cgroup_mutex); |
2219449a TH |
87 | #endif |
88 | ||
e25e2cbb | 89 | static DEFINE_MUTEX(cgroup_root_mutex); |
81a6a5cd | 90 | |
aae8aab4 BB |
91 | /* |
92 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
be45c900 | 93 | * populated with the built in subsystems, and modular subsystems are |
aae8aab4 BB |
94 | * registered after that. The mutable section of this array is protected by |
95 | * cgroup_mutex. | |
96 | */ | |
80f4c877 | 97 | #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, |
5fc0b025 | 98 | #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) |
9871bf95 | 99 | static struct cgroup_subsys *cgroup_subsys[CGROUP_SUBSYS_COUNT] = { |
ddbcc7e8 PM |
100 | #include <linux/cgroup_subsys.h> |
101 | }; | |
102 | ||
ddbcc7e8 | 103 | /* |
9871bf95 TH |
104 | * The dummy hierarchy, reserved for the subsystems that are otherwise |
105 | * unattached - it never has more than a single cgroup, and all tasks are | |
106 | * part of that cgroup. | |
ddbcc7e8 | 107 | */ |
9871bf95 TH |
108 | static struct cgroupfs_root cgroup_dummy_root; |
109 | ||
110 | /* dummy_top is a shorthand for the dummy hierarchy's top cgroup */ | |
111 | static struct cgroup * const cgroup_dummy_top = &cgroup_dummy_root.top_cgroup; | |
ddbcc7e8 | 112 | |
05ef1d7c TH |
113 | /* |
114 | * cgroupfs file entry, pointed to from leaf dentry->d_fsdata. | |
115 | */ | |
116 | struct cfent { | |
117 | struct list_head node; | |
118 | struct dentry *dentry; | |
119 | struct cftype *type; | |
712317ad LZ |
120 | |
121 | /* file xattrs */ | |
122 | struct simple_xattrs xattrs; | |
05ef1d7c TH |
123 | }; |
124 | ||
38460b48 KH |
125 | /* |
126 | * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when | |
127 | * cgroup_subsys->use_id != 0. | |
128 | */ | |
129 | #define CSS_ID_MAX (65535) | |
130 | struct css_id { | |
131 | /* | |
132 | * The css to which this ID points. This pointer is set to valid value | |
133 | * after cgroup is populated. If cgroup is removed, this will be NULL. | |
134 | * This pointer is expected to be RCU-safe because destroy() | |
e9316080 TH |
135 | * is called after synchronize_rcu(). But for safe use, css_tryget() |
136 | * should be used for avoiding race. | |
38460b48 | 137 | */ |
2c392b8c | 138 | struct cgroup_subsys_state __rcu *css; |
38460b48 KH |
139 | /* |
140 | * ID of this css. | |
141 | */ | |
142 | unsigned short id; | |
143 | /* | |
144 | * Depth in hierarchy which this ID belongs to. | |
145 | */ | |
146 | unsigned short depth; | |
147 | /* | |
148 | * ID is freed by RCU. (and lookup routine is RCU safe.) | |
149 | */ | |
150 | struct rcu_head rcu_head; | |
151 | /* | |
152 | * Hierarchy of CSS ID belongs to. | |
153 | */ | |
154 | unsigned short stack[0]; /* Array of Length (depth+1) */ | |
155 | }; | |
156 | ||
0dea1168 | 157 | /* |
25985edc | 158 | * cgroup_event represents events which userspace want to receive. |
0dea1168 KS |
159 | */ |
160 | struct cgroup_event { | |
161 | /* | |
162 | * Cgroup which the event belongs to. | |
163 | */ | |
164 | struct cgroup *cgrp; | |
165 | /* | |
166 | * Control file which the event associated. | |
167 | */ | |
168 | struct cftype *cft; | |
169 | /* | |
170 | * eventfd to signal userspace about the event. | |
171 | */ | |
172 | struct eventfd_ctx *eventfd; | |
173 | /* | |
174 | * Each of these stored in a list by the cgroup. | |
175 | */ | |
176 | struct list_head list; | |
177 | /* | |
178 | * All fields below needed to unregister event when | |
179 | * userspace closes eventfd. | |
180 | */ | |
181 | poll_table pt; | |
182 | wait_queue_head_t *wqh; | |
183 | wait_queue_t wait; | |
184 | struct work_struct remove; | |
185 | }; | |
38460b48 | 186 | |
ddbcc7e8 PM |
187 | /* The list of hierarchy roots */ |
188 | ||
9871bf95 TH |
189 | static LIST_HEAD(cgroup_roots); |
190 | static int cgroup_root_count; | |
ddbcc7e8 | 191 | |
54e7b4eb TH |
192 | /* |
193 | * Hierarchy ID allocation and mapping. It follows the same exclusion | |
194 | * rules as other root ops - both cgroup_mutex and cgroup_root_mutex for | |
195 | * writes, either for reads. | |
196 | */ | |
1a574231 | 197 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 198 | |
65dff759 LZ |
199 | static struct cgroup_name root_cgroup_name = { .name = "/" }; |
200 | ||
794611a1 LZ |
201 | /* |
202 | * Assign a monotonically increasing serial number to cgroups. It | |
203 | * guarantees cgroups with bigger numbers are newer than those with smaller | |
204 | * numbers. Also, as cgroups are always appended to the parent's | |
205 | * ->children list, it guarantees that sibling cgroups are always sorted in | |
00356bd5 TH |
206 | * the ascending serial number order on the list. Protected by |
207 | * cgroup_mutex. | |
794611a1 | 208 | */ |
00356bd5 | 209 | static u64 cgroup_serial_nr_next = 1; |
794611a1 | 210 | |
ddbcc7e8 | 211 | /* This flag indicates whether tasks in the fork and exit paths should |
a043e3b2 LZ |
212 | * check for fork/exit handlers to call. This avoids us having to do |
213 | * extra work in the fork/exit path if none of the subsystems need to | |
214 | * be called. | |
ddbcc7e8 | 215 | */ |
8947f9d5 | 216 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 217 | |
628f7cd4 TH |
218 | static struct cftype cgroup_base_files[]; |
219 | ||
ea15f8cc | 220 | static void cgroup_offline_fn(struct work_struct *work); |
42809dd4 | 221 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
2bb566cb TH |
222 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
223 | bool is_add); | |
42809dd4 | 224 | |
ddbcc7e8 | 225 | /* convenient tests for these bits */ |
54766d4a | 226 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 227 | { |
54766d4a | 228 | return test_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 PM |
229 | } |
230 | ||
78574cf9 LZ |
231 | /** |
232 | * cgroup_is_descendant - test ancestry | |
233 | * @cgrp: the cgroup to be tested | |
234 | * @ancestor: possible ancestor of @cgrp | |
235 | * | |
236 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
237 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
238 | * and @ancestor are accessible. | |
239 | */ | |
240 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
241 | { | |
242 | while (cgrp) { | |
243 | if (cgrp == ancestor) | |
244 | return true; | |
245 | cgrp = cgrp->parent; | |
246 | } | |
247 | return false; | |
248 | } | |
249 | EXPORT_SYMBOL_GPL(cgroup_is_descendant); | |
ddbcc7e8 | 250 | |
e9685a03 | 251 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
252 | { |
253 | const int bits = | |
bd89aabc PM |
254 | (1 << CGRP_RELEASABLE) | |
255 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
256 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
257 | } |
258 | ||
e9685a03 | 259 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 260 | { |
bd89aabc | 261 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
262 | } |
263 | ||
30159ec7 TH |
264 | /** |
265 | * for_each_subsys - iterate all loaded cgroup subsystems | |
266 | * @ss: the iteration cursor | |
267 | * @i: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end | |
268 | * | |
269 | * Should be called under cgroup_mutex. | |
270 | */ | |
271 | #define for_each_subsys(ss, i) \ | |
272 | for ((i) = 0; (i) < CGROUP_SUBSYS_COUNT; (i)++) \ | |
273 | if (({ lockdep_assert_held(&cgroup_mutex); \ | |
274 | !((ss) = cgroup_subsys[i]); })) { } \ | |
275 | else | |
276 | ||
277 | /** | |
278 | * for_each_builtin_subsys - iterate all built-in cgroup subsystems | |
279 | * @ss: the iteration cursor | |
280 | * @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end | |
281 | * | |
282 | * Bulit-in subsystems are always present and iteration itself doesn't | |
283 | * require any synchronization. | |
284 | */ | |
285 | #define for_each_builtin_subsys(ss, i) \ | |
286 | for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \ | |
287 | (((ss) = cgroup_subsys[i]) || true); (i)++) | |
288 | ||
5549c497 TH |
289 | /* iterate each subsystem attached to a hierarchy */ |
290 | #define for_each_root_subsys(root, ss) \ | |
291 | list_for_each_entry((ss), &(root)->subsys_list, sibling) | |
ddbcc7e8 | 292 | |
5549c497 TH |
293 | /* iterate across the active hierarchies */ |
294 | #define for_each_active_root(root) \ | |
295 | list_for_each_entry((root), &cgroup_roots, root_list) | |
ddbcc7e8 | 296 | |
f6ea9372 TH |
297 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
298 | { | |
299 | return dentry->d_fsdata; | |
300 | } | |
301 | ||
05ef1d7c | 302 | static inline struct cfent *__d_cfe(struct dentry *dentry) |
f6ea9372 TH |
303 | { |
304 | return dentry->d_fsdata; | |
305 | } | |
306 | ||
05ef1d7c TH |
307 | static inline struct cftype *__d_cft(struct dentry *dentry) |
308 | { | |
309 | return __d_cfe(dentry)->type; | |
310 | } | |
311 | ||
7ae1bad9 TH |
312 | /** |
313 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
314 | * @cgrp: the cgroup to be checked for liveness | |
315 | * | |
47cfcd09 TH |
316 | * On success, returns true; the mutex should be later unlocked. On |
317 | * failure returns false with no lock held. | |
7ae1bad9 | 318 | */ |
b9777cf8 | 319 | static bool cgroup_lock_live_group(struct cgroup *cgrp) |
7ae1bad9 TH |
320 | { |
321 | mutex_lock(&cgroup_mutex); | |
54766d4a | 322 | if (cgroup_is_dead(cgrp)) { |
7ae1bad9 TH |
323 | mutex_unlock(&cgroup_mutex); |
324 | return false; | |
325 | } | |
326 | return true; | |
327 | } | |
7ae1bad9 | 328 | |
81a6a5cd PM |
329 | /* the list of cgroups eligible for automatic release. Protected by |
330 | * release_list_lock */ | |
331 | static LIST_HEAD(release_list); | |
cdcc136f | 332 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
333 | static void cgroup_release_agent(struct work_struct *work); |
334 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 335 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 336 | |
69d0206c TH |
337 | /* |
338 | * A cgroup can be associated with multiple css_sets as different tasks may | |
339 | * belong to different cgroups on different hierarchies. In the other | |
340 | * direction, a css_set is naturally associated with multiple cgroups. | |
341 | * This M:N relationship is represented by the following link structure | |
342 | * which exists for each association and allows traversing the associations | |
343 | * from both sides. | |
344 | */ | |
345 | struct cgrp_cset_link { | |
346 | /* the cgroup and css_set this link associates */ | |
347 | struct cgroup *cgrp; | |
348 | struct css_set *cset; | |
349 | ||
350 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
351 | struct list_head cset_link; | |
352 | ||
353 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
354 | struct list_head cgrp_link; | |
817929ec PM |
355 | }; |
356 | ||
357 | /* The default css_set - used by init and its children prior to any | |
358 | * hierarchies being mounted. It contains a pointer to the root state | |
359 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
360 | * reference-counted, to improve performance when child cgroups | |
361 | * haven't been created. | |
362 | */ | |
363 | ||
364 | static struct css_set init_css_set; | |
69d0206c | 365 | static struct cgrp_cset_link init_cgrp_cset_link; |
817929ec | 366 | |
e6a1105b BB |
367 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
368 | struct cgroup_subsys_state *css); | |
38460b48 | 369 | |
0942eeee TH |
370 | /* |
371 | * css_set_lock protects the list of css_set objects, and the chain of | |
372 | * tasks off each css_set. Nests outside task->alloc_lock due to | |
373 | * cgroup_task_iter_start(). | |
374 | */ | |
817929ec PM |
375 | static DEFINE_RWLOCK(css_set_lock); |
376 | static int css_set_count; | |
377 | ||
7717f7ba PM |
378 | /* |
379 | * hash table for cgroup groups. This improves the performance to find | |
380 | * an existing css_set. This hash doesn't (currently) take into | |
381 | * account cgroups in empty hierarchies. | |
382 | */ | |
472b1053 | 383 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 384 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 385 | |
0ac801fe | 386 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 387 | { |
0ac801fe | 388 | unsigned long key = 0UL; |
30159ec7 TH |
389 | struct cgroup_subsys *ss; |
390 | int i; | |
472b1053 | 391 | |
30159ec7 | 392 | for_each_subsys(ss, i) |
0ac801fe LZ |
393 | key += (unsigned long)css[i]; |
394 | key = (key >> 16) ^ key; | |
472b1053 | 395 | |
0ac801fe | 396 | return key; |
472b1053 LZ |
397 | } |
398 | ||
0942eeee TH |
399 | /* |
400 | * We don't maintain the lists running through each css_set to its task | |
401 | * until after the first call to cgroup_task_iter_start(). This reduces | |
402 | * the fork()/exit() overhead for people who have cgroups compiled into | |
403 | * their kernel but not actually in use. | |
404 | */ | |
8947f9d5 | 405 | static int use_task_css_set_links __read_mostly; |
817929ec | 406 | |
5abb8855 | 407 | static void __put_css_set(struct css_set *cset, int taskexit) |
b4f48b63 | 408 | { |
69d0206c | 409 | struct cgrp_cset_link *link, *tmp_link; |
5abb8855 | 410 | |
146aa1bd LJ |
411 | /* |
412 | * Ensure that the refcount doesn't hit zero while any readers | |
413 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
414 | * rwlock | |
415 | */ | |
5abb8855 | 416 | if (atomic_add_unless(&cset->refcount, -1, 1)) |
146aa1bd LJ |
417 | return; |
418 | write_lock(&css_set_lock); | |
5abb8855 | 419 | if (!atomic_dec_and_test(&cset->refcount)) { |
146aa1bd LJ |
420 | write_unlock(&css_set_lock); |
421 | return; | |
422 | } | |
81a6a5cd | 423 | |
2c6ab6d2 | 424 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
5abb8855 | 425 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
426 | css_set_count--; |
427 | ||
69d0206c | 428 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 429 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 430 | |
69d0206c TH |
431 | list_del(&link->cset_link); |
432 | list_del(&link->cgrp_link); | |
71b5707e | 433 | |
ddd69148 | 434 | /* @cgrp can't go away while we're holding css_set_lock */ |
6f3d828f | 435 | if (list_empty(&cgrp->cset_links) && notify_on_release(cgrp)) { |
81a6a5cd | 436 | if (taskexit) |
bd89aabc PM |
437 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
438 | check_for_release(cgrp); | |
81a6a5cd | 439 | } |
2c6ab6d2 PM |
440 | |
441 | kfree(link); | |
81a6a5cd | 442 | } |
2c6ab6d2 PM |
443 | |
444 | write_unlock(&css_set_lock); | |
5abb8855 | 445 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
446 | } |
447 | ||
817929ec PM |
448 | /* |
449 | * refcounted get/put for css_set objects | |
450 | */ | |
5abb8855 | 451 | static inline void get_css_set(struct css_set *cset) |
817929ec | 452 | { |
5abb8855 | 453 | atomic_inc(&cset->refcount); |
817929ec PM |
454 | } |
455 | ||
5abb8855 | 456 | static inline void put_css_set(struct css_set *cset) |
817929ec | 457 | { |
5abb8855 | 458 | __put_css_set(cset, 0); |
817929ec PM |
459 | } |
460 | ||
5abb8855 | 461 | static inline void put_css_set_taskexit(struct css_set *cset) |
81a6a5cd | 462 | { |
5abb8855 | 463 | __put_css_set(cset, 1); |
81a6a5cd PM |
464 | } |
465 | ||
b326f9d0 | 466 | /** |
7717f7ba | 467 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
468 | * @cset: candidate css_set being tested |
469 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
470 | * @new_cgrp: cgroup that's being entered by the task |
471 | * @template: desired set of css pointers in css_set (pre-calculated) | |
472 | * | |
6f4b7e63 | 473 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
474 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
475 | */ | |
5abb8855 TH |
476 | static bool compare_css_sets(struct css_set *cset, |
477 | struct css_set *old_cset, | |
7717f7ba PM |
478 | struct cgroup *new_cgrp, |
479 | struct cgroup_subsys_state *template[]) | |
480 | { | |
481 | struct list_head *l1, *l2; | |
482 | ||
5abb8855 | 483 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) { |
7717f7ba PM |
484 | /* Not all subsystems matched */ |
485 | return false; | |
486 | } | |
487 | ||
488 | /* | |
489 | * Compare cgroup pointers in order to distinguish between | |
490 | * different cgroups in heirarchies with no subsystems. We | |
491 | * could get by with just this check alone (and skip the | |
492 | * memcmp above) but on most setups the memcmp check will | |
493 | * avoid the need for this more expensive check on almost all | |
494 | * candidates. | |
495 | */ | |
496 | ||
69d0206c TH |
497 | l1 = &cset->cgrp_links; |
498 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 499 | while (1) { |
69d0206c | 500 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 501 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
502 | |
503 | l1 = l1->next; | |
504 | l2 = l2->next; | |
505 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
506 | if (l1 == &cset->cgrp_links) { |
507 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
508 | break; |
509 | } else { | |
69d0206c | 510 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
511 | } |
512 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
513 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
514 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
515 | cgrp1 = link1->cgrp; | |
516 | cgrp2 = link2->cgrp; | |
7717f7ba | 517 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 518 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
519 | |
520 | /* | |
521 | * If this hierarchy is the hierarchy of the cgroup | |
522 | * that's changing, then we need to check that this | |
523 | * css_set points to the new cgroup; if it's any other | |
524 | * hierarchy, then this css_set should point to the | |
525 | * same cgroup as the old css_set. | |
526 | */ | |
5abb8855 TH |
527 | if (cgrp1->root == new_cgrp->root) { |
528 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
529 | return false; |
530 | } else { | |
5abb8855 | 531 | if (cgrp1 != cgrp2) |
7717f7ba PM |
532 | return false; |
533 | } | |
534 | } | |
535 | return true; | |
536 | } | |
537 | ||
b326f9d0 TH |
538 | /** |
539 | * find_existing_css_set - init css array and find the matching css_set | |
540 | * @old_cset: the css_set that we're using before the cgroup transition | |
541 | * @cgrp: the cgroup that we're moving into | |
542 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 543 | */ |
5abb8855 TH |
544 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
545 | struct cgroup *cgrp, | |
546 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 547 | { |
bd89aabc | 548 | struct cgroupfs_root *root = cgrp->root; |
30159ec7 | 549 | struct cgroup_subsys *ss; |
5abb8855 | 550 | struct css_set *cset; |
0ac801fe | 551 | unsigned long key; |
b326f9d0 | 552 | int i; |
817929ec | 553 | |
aae8aab4 BB |
554 | /* |
555 | * Build the set of subsystem state objects that we want to see in the | |
556 | * new css_set. while subsystems can change globally, the entries here | |
557 | * won't change, so no need for locking. | |
558 | */ | |
30159ec7 | 559 | for_each_subsys(ss, i) { |
a1a71b45 | 560 | if (root->subsys_mask & (1UL << i)) { |
817929ec PM |
561 | /* Subsystem is in this hierarchy. So we want |
562 | * the subsystem state from the new | |
563 | * cgroup */ | |
bd89aabc | 564 | template[i] = cgrp->subsys[i]; |
817929ec PM |
565 | } else { |
566 | /* Subsystem is not in this hierarchy, so we | |
567 | * don't want to change the subsystem state */ | |
5abb8855 | 568 | template[i] = old_cset->subsys[i]; |
817929ec PM |
569 | } |
570 | } | |
571 | ||
0ac801fe | 572 | key = css_set_hash(template); |
5abb8855 TH |
573 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
574 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
575 | continue; |
576 | ||
577 | /* This css_set matches what we need */ | |
5abb8855 | 578 | return cset; |
472b1053 | 579 | } |
817929ec PM |
580 | |
581 | /* No existing cgroup group matched */ | |
582 | return NULL; | |
583 | } | |
584 | ||
69d0206c | 585 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 586 | { |
69d0206c | 587 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 588 | |
69d0206c TH |
589 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
590 | list_del(&link->cset_link); | |
36553434 LZ |
591 | kfree(link); |
592 | } | |
593 | } | |
594 | ||
69d0206c TH |
595 | /** |
596 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
597 | * @count: the number of links to allocate | |
598 | * @tmp_links: list_head the allocated links are put on | |
599 | * | |
600 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
601 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 602 | */ |
69d0206c | 603 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 604 | { |
69d0206c | 605 | struct cgrp_cset_link *link; |
817929ec | 606 | int i; |
69d0206c TH |
607 | |
608 | INIT_LIST_HEAD(tmp_links); | |
609 | ||
817929ec | 610 | for (i = 0; i < count; i++) { |
f4f4be2b | 611 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 612 | if (!link) { |
69d0206c | 613 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
614 | return -ENOMEM; |
615 | } | |
69d0206c | 616 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
617 | } |
618 | return 0; | |
619 | } | |
620 | ||
c12f65d4 LZ |
621 | /** |
622 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 623 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 624 | * @cset: the css_set to be linked |
c12f65d4 LZ |
625 | * @cgrp: the destination cgroup |
626 | */ | |
69d0206c TH |
627 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
628 | struct cgroup *cgrp) | |
c12f65d4 | 629 | { |
69d0206c | 630 | struct cgrp_cset_link *link; |
c12f65d4 | 631 | |
69d0206c TH |
632 | BUG_ON(list_empty(tmp_links)); |
633 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); | |
634 | link->cset = cset; | |
7717f7ba | 635 | link->cgrp = cgrp; |
69d0206c | 636 | list_move(&link->cset_link, &cgrp->cset_links); |
7717f7ba PM |
637 | /* |
638 | * Always add links to the tail of the list so that the list | |
639 | * is sorted by order of hierarchy creation | |
640 | */ | |
69d0206c | 641 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
642 | } |
643 | ||
b326f9d0 TH |
644 | /** |
645 | * find_css_set - return a new css_set with one cgroup updated | |
646 | * @old_cset: the baseline css_set | |
647 | * @cgrp: the cgroup to be updated | |
648 | * | |
649 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
650 | * substituted into the appropriate hierarchy. | |
817929ec | 651 | */ |
5abb8855 TH |
652 | static struct css_set *find_css_set(struct css_set *old_cset, |
653 | struct cgroup *cgrp) | |
817929ec | 654 | { |
b326f9d0 | 655 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 656 | struct css_set *cset; |
69d0206c TH |
657 | struct list_head tmp_links; |
658 | struct cgrp_cset_link *link; | |
0ac801fe | 659 | unsigned long key; |
472b1053 | 660 | |
b326f9d0 TH |
661 | lockdep_assert_held(&cgroup_mutex); |
662 | ||
817929ec PM |
663 | /* First see if we already have a cgroup group that matches |
664 | * the desired set */ | |
7e9abd89 | 665 | read_lock(&css_set_lock); |
5abb8855 TH |
666 | cset = find_existing_css_set(old_cset, cgrp, template); |
667 | if (cset) | |
668 | get_css_set(cset); | |
7e9abd89 | 669 | read_unlock(&css_set_lock); |
817929ec | 670 | |
5abb8855 TH |
671 | if (cset) |
672 | return cset; | |
817929ec | 673 | |
f4f4be2b | 674 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 675 | if (!cset) |
817929ec PM |
676 | return NULL; |
677 | ||
69d0206c | 678 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 679 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 680 | kfree(cset); |
817929ec PM |
681 | return NULL; |
682 | } | |
683 | ||
5abb8855 | 684 | atomic_set(&cset->refcount, 1); |
69d0206c | 685 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 TH |
686 | INIT_LIST_HEAD(&cset->tasks); |
687 | INIT_HLIST_NODE(&cset->hlist); | |
817929ec PM |
688 | |
689 | /* Copy the set of subsystem state objects generated in | |
690 | * find_existing_css_set() */ | |
5abb8855 | 691 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec PM |
692 | |
693 | write_lock(&css_set_lock); | |
694 | /* Add reference counts and links from the new css_set. */ | |
69d0206c | 695 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 696 | struct cgroup *c = link->cgrp; |
69d0206c | 697 | |
7717f7ba PM |
698 | if (c->root == cgrp->root) |
699 | c = cgrp; | |
69d0206c | 700 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 701 | } |
817929ec | 702 | |
69d0206c | 703 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 704 | |
817929ec | 705 | css_set_count++; |
472b1053 LZ |
706 | |
707 | /* Add this cgroup group to the hash table */ | |
5abb8855 TH |
708 | key = css_set_hash(cset->subsys); |
709 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 710 | |
817929ec PM |
711 | write_unlock(&css_set_lock); |
712 | ||
5abb8855 | 713 | return cset; |
b4f48b63 PM |
714 | } |
715 | ||
7717f7ba PM |
716 | /* |
717 | * Return the cgroup for "task" from the given hierarchy. Must be | |
718 | * called with cgroup_mutex held. | |
719 | */ | |
720 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
721 | struct cgroupfs_root *root) | |
722 | { | |
5abb8855 | 723 | struct css_set *cset; |
7717f7ba PM |
724 | struct cgroup *res = NULL; |
725 | ||
726 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
727 | read_lock(&css_set_lock); | |
728 | /* | |
729 | * No need to lock the task - since we hold cgroup_mutex the | |
730 | * task can't change groups, so the only thing that can happen | |
731 | * is that it exits and its css is set back to init_css_set. | |
732 | */ | |
a8ad805c | 733 | cset = task_css_set(task); |
5abb8855 | 734 | if (cset == &init_css_set) { |
7717f7ba PM |
735 | res = &root->top_cgroup; |
736 | } else { | |
69d0206c TH |
737 | struct cgrp_cset_link *link; |
738 | ||
739 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 740 | struct cgroup *c = link->cgrp; |
69d0206c | 741 | |
7717f7ba PM |
742 | if (c->root == root) { |
743 | res = c; | |
744 | break; | |
745 | } | |
746 | } | |
747 | } | |
748 | read_unlock(&css_set_lock); | |
749 | BUG_ON(!res); | |
750 | return res; | |
751 | } | |
752 | ||
ddbcc7e8 PM |
753 | /* |
754 | * There is one global cgroup mutex. We also require taking | |
755 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
756 | * See "The task_lock() exception", at the end of this comment. | |
757 | * | |
758 | * A task must hold cgroup_mutex to modify cgroups. | |
759 | * | |
760 | * Any task can increment and decrement the count field without lock. | |
761 | * So in general, code holding cgroup_mutex can't rely on the count | |
762 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 763 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
764 | * means that no tasks are currently attached, therefore there is no |
765 | * way a task attached to that cgroup can fork (the other way to | |
766 | * increment the count). So code holding cgroup_mutex can safely | |
767 | * assume that if the count is zero, it will stay zero. Similarly, if | |
768 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
769 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
770 | * needs that mutex. | |
771 | * | |
ddbcc7e8 PM |
772 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
773 | * (usually) take cgroup_mutex. These are the two most performance | |
774 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
775 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
776 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
777 | * to the release agent with the name of the cgroup (path relative to |
778 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
779 | * |
780 | * A cgroup can only be deleted if both its 'count' of using tasks | |
781 | * is zero, and its list of 'children' cgroups is empty. Since all | |
782 | * tasks in the system use _some_ cgroup, and since there is always at | |
783 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
784 | * always has either children cgroups and/or using tasks. So we don't | |
785 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
786 | * | |
787 | * The task_lock() exception | |
788 | * | |
789 | * The need for this exception arises from the action of | |
d0b2fdd2 | 790 | * cgroup_attach_task(), which overwrites one task's cgroup pointer with |
a043e3b2 | 791 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
792 | * several performance critical places that need to reference |
793 | * task->cgroup without the expense of grabbing a system global | |
794 | * mutex. Therefore except as noted below, when dereferencing or, as | |
d0b2fdd2 | 795 | * in cgroup_attach_task(), modifying a task's cgroup pointer we use |
ddbcc7e8 PM |
796 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
797 | * the task_struct routinely used for such matters. | |
798 | * | |
799 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 800 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
801 | */ |
802 | ||
ddbcc7e8 PM |
803 | /* |
804 | * A couple of forward declarations required, due to cyclic reference loop: | |
805 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
806 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
807 | * -> cgroup_mkdir. | |
808 | */ | |
809 | ||
18bb1db3 | 810 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); |
00cd8dd3 | 811 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int); |
ddbcc7e8 | 812 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
628f7cd4 | 813 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); |
6e1d5dcc | 814 | static const struct inode_operations cgroup_dir_inode_operations; |
828c0950 | 815 | static const struct file_operations proc_cgroupstats_operations; |
a424316c PM |
816 | |
817 | static struct backing_dev_info cgroup_backing_dev_info = { | |
d993831f | 818 | .name = "cgroup", |
e4ad08fe | 819 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 820 | }; |
ddbcc7e8 | 821 | |
38460b48 KH |
822 | static int alloc_css_id(struct cgroup_subsys *ss, |
823 | struct cgroup *parent, struct cgroup *child); | |
824 | ||
a5e7ed32 | 825 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) |
ddbcc7e8 PM |
826 | { |
827 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
828 | |
829 | if (inode) { | |
85fe4025 | 830 | inode->i_ino = get_next_ino(); |
ddbcc7e8 | 831 | inode->i_mode = mode; |
76aac0e9 DH |
832 | inode->i_uid = current_fsuid(); |
833 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
834 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
835 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
836 | } | |
837 | return inode; | |
838 | } | |
839 | ||
65dff759 LZ |
840 | static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry) |
841 | { | |
842 | struct cgroup_name *name; | |
843 | ||
844 | name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL); | |
845 | if (!name) | |
846 | return NULL; | |
847 | strcpy(name->name, dentry->d_name.name); | |
848 | return name; | |
849 | } | |
850 | ||
be445626 LZ |
851 | static void cgroup_free_fn(struct work_struct *work) |
852 | { | |
ea15f8cc | 853 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); |
be445626 LZ |
854 | struct cgroup_subsys *ss; |
855 | ||
856 | mutex_lock(&cgroup_mutex); | |
857 | /* | |
858 | * Release the subsystem state objects. | |
859 | */ | |
eb95419b TH |
860 | for_each_root_subsys(cgrp->root, ss) { |
861 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
862 | ||
863 | ss->css_free(css); | |
864 | } | |
be445626 LZ |
865 | |
866 | cgrp->root->number_of_cgroups--; | |
867 | mutex_unlock(&cgroup_mutex); | |
868 | ||
415cf07a LZ |
869 | /* |
870 | * We get a ref to the parent's dentry, and put the ref when | |
871 | * this cgroup is being freed, so it's guaranteed that the | |
872 | * parent won't be destroyed before its children. | |
873 | */ | |
874 | dput(cgrp->parent->dentry); | |
875 | ||
be445626 LZ |
876 | /* |
877 | * Drop the active superblock reference that we took when we | |
cc20e01c LZ |
878 | * created the cgroup. This will free cgrp->root, if we are |
879 | * holding the last reference to @sb. | |
be445626 LZ |
880 | */ |
881 | deactivate_super(cgrp->root->sb); | |
882 | ||
883 | /* | |
884 | * if we're getting rid of the cgroup, refcount should ensure | |
885 | * that there are no pidlists left. | |
886 | */ | |
887 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
888 | ||
889 | simple_xattrs_free(&cgrp->xattrs); | |
890 | ||
65dff759 | 891 | kfree(rcu_dereference_raw(cgrp->name)); |
be445626 LZ |
892 | kfree(cgrp); |
893 | } | |
894 | ||
895 | static void cgroup_free_rcu(struct rcu_head *head) | |
896 | { | |
897 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); | |
898 | ||
ea15f8cc TH |
899 | INIT_WORK(&cgrp->destroy_work, cgroup_free_fn); |
900 | schedule_work(&cgrp->destroy_work); | |
be445626 LZ |
901 | } |
902 | ||
ddbcc7e8 PM |
903 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
904 | { | |
905 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
906 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 907 | struct cgroup *cgrp = dentry->d_fsdata; |
be445626 | 908 | |
54766d4a | 909 | BUG_ON(!(cgroup_is_dead(cgrp))); |
be445626 | 910 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
05ef1d7c TH |
911 | } else { |
912 | struct cfent *cfe = __d_cfe(dentry); | |
913 | struct cgroup *cgrp = dentry->d_parent->d_fsdata; | |
914 | ||
915 | WARN_ONCE(!list_empty(&cfe->node) && | |
916 | cgrp != &cgrp->root->top_cgroup, | |
917 | "cfe still linked for %s\n", cfe->type->name); | |
712317ad | 918 | simple_xattrs_free(&cfe->xattrs); |
05ef1d7c | 919 | kfree(cfe); |
ddbcc7e8 PM |
920 | } |
921 | iput(inode); | |
922 | } | |
923 | ||
c72a04e3 AV |
924 | static int cgroup_delete(const struct dentry *d) |
925 | { | |
926 | return 1; | |
927 | } | |
928 | ||
ddbcc7e8 PM |
929 | static void remove_dir(struct dentry *d) |
930 | { | |
931 | struct dentry *parent = dget(d->d_parent); | |
932 | ||
933 | d_delete(d); | |
934 | simple_rmdir(parent->d_inode, d); | |
935 | dput(parent); | |
936 | } | |
937 | ||
2739d3cc | 938 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c TH |
939 | { |
940 | struct cfent *cfe; | |
941 | ||
942 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); | |
943 | lockdep_assert_held(&cgroup_mutex); | |
944 | ||
2739d3cc LZ |
945 | /* |
946 | * If we're doing cleanup due to failure of cgroup_create(), | |
947 | * the corresponding @cfe may not exist. | |
948 | */ | |
05ef1d7c TH |
949 | list_for_each_entry(cfe, &cgrp->files, node) { |
950 | struct dentry *d = cfe->dentry; | |
951 | ||
952 | if (cft && cfe->type != cft) | |
953 | continue; | |
954 | ||
955 | dget(d); | |
956 | d_delete(d); | |
ce27e317 | 957 | simple_unlink(cgrp->dentry->d_inode, d); |
05ef1d7c TH |
958 | list_del_init(&cfe->node); |
959 | dput(d); | |
960 | ||
2739d3cc | 961 | break; |
ddbcc7e8 | 962 | } |
05ef1d7c TH |
963 | } |
964 | ||
13af07df | 965 | /** |
628f7cd4 | 966 | * cgroup_clear_dir - remove subsys files in a cgroup directory |
8f89140a | 967 | * @cgrp: target cgroup |
13af07df AR |
968 | * @subsys_mask: mask of the subsystem ids whose files should be removed |
969 | */ | |
628f7cd4 | 970 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
05ef1d7c | 971 | { |
13af07df | 972 | struct cgroup_subsys *ss; |
b420ba7d | 973 | int i; |
05ef1d7c | 974 | |
b420ba7d | 975 | for_each_subsys(ss, i) { |
13af07df | 976 | struct cftype_set *set; |
b420ba7d TH |
977 | |
978 | if (!test_bit(i, &subsys_mask)) | |
13af07df AR |
979 | continue; |
980 | list_for_each_entry(set, &ss->cftsets, node) | |
2bb566cb | 981 | cgroup_addrm_files(cgrp, set->cfts, false); |
13af07df | 982 | } |
ddbcc7e8 PM |
983 | } |
984 | ||
985 | /* | |
986 | * NOTE : the dentry must have been dget()'ed | |
987 | */ | |
988 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
989 | { | |
2fd6b7f5 | 990 | struct dentry *parent; |
ddbcc7e8 | 991 | |
2fd6b7f5 NP |
992 | parent = dentry->d_parent; |
993 | spin_lock(&parent->d_lock); | |
3ec762ad | 994 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
ddbcc7e8 | 995 | list_del_init(&dentry->d_u.d_child); |
2fd6b7f5 NP |
996 | spin_unlock(&dentry->d_lock); |
997 | spin_unlock(&parent->d_lock); | |
ddbcc7e8 PM |
998 | remove_dir(dentry); |
999 | } | |
1000 | ||
aae8aab4 | 1001 | /* |
cf5d5941 BB |
1002 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
1003 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
1004 | * returns an error, no reference counts are touched. | |
aae8aab4 | 1005 | */ |
ddbcc7e8 | 1006 | static int rebind_subsystems(struct cgroupfs_root *root, |
a8a648c4 | 1007 | unsigned long added_mask, unsigned removed_mask) |
ddbcc7e8 | 1008 | { |
bd89aabc | 1009 | struct cgroup *cgrp = &root->top_cgroup; |
30159ec7 | 1010 | struct cgroup_subsys *ss; |
1d5be6b2 | 1011 | unsigned long pinned = 0; |
3126121f | 1012 | int i, ret; |
ddbcc7e8 | 1013 | |
aae8aab4 | 1014 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
e25e2cbb | 1015 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); |
aae8aab4 | 1016 | |
ddbcc7e8 | 1017 | /* Check that any added subsystems are currently free */ |
30159ec7 | 1018 | for_each_subsys(ss, i) { |
1d5be6b2 | 1019 | if (!(added_mask & (1 << i))) |
ddbcc7e8 | 1020 | continue; |
30159ec7 | 1021 | |
1d5be6b2 | 1022 | /* is the subsystem mounted elsewhere? */ |
9871bf95 | 1023 | if (ss->root != &cgroup_dummy_root) { |
1d5be6b2 TH |
1024 | ret = -EBUSY; |
1025 | goto out_put; | |
1026 | } | |
1027 | ||
1028 | /* pin the module */ | |
1029 | if (!try_module_get(ss->module)) { | |
1030 | ret = -ENOENT; | |
1031 | goto out_put; | |
ddbcc7e8 | 1032 | } |
1d5be6b2 TH |
1033 | pinned |= 1 << i; |
1034 | } | |
1035 | ||
1036 | /* subsys could be missing if unloaded between parsing and here */ | |
1037 | if (added_mask != pinned) { | |
1038 | ret = -ENOENT; | |
1039 | goto out_put; | |
ddbcc7e8 PM |
1040 | } |
1041 | ||
3126121f TH |
1042 | ret = cgroup_populate_dir(cgrp, added_mask); |
1043 | if (ret) | |
1d5be6b2 | 1044 | goto out_put; |
3126121f TH |
1045 | |
1046 | /* | |
1047 | * Nothing can fail from this point on. Remove files for the | |
1048 | * removed subsystems and rebind each subsystem. | |
1049 | */ | |
1050 | cgroup_clear_dir(cgrp, removed_mask); | |
1051 | ||
30159ec7 | 1052 | for_each_subsys(ss, i) { |
ddbcc7e8 | 1053 | unsigned long bit = 1UL << i; |
30159ec7 | 1054 | |
a1a71b45 | 1055 | if (bit & added_mask) { |
ddbcc7e8 | 1056 | /* We're binding this subsystem to this hierarchy */ |
bd89aabc | 1057 | BUG_ON(cgrp->subsys[i]); |
9871bf95 TH |
1058 | BUG_ON(!cgroup_dummy_top->subsys[i]); |
1059 | BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top); | |
a8a648c4 | 1060 | |
9871bf95 | 1061 | cgrp->subsys[i] = cgroup_dummy_top->subsys[i]; |
bd89aabc | 1062 | cgrp->subsys[i]->cgroup = cgrp; |
33a68ac1 | 1063 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 1064 | ss->root = root; |
ddbcc7e8 | 1065 | if (ss->bind) |
eb95419b | 1066 | ss->bind(cgrp->subsys[i]); |
a8a648c4 | 1067 | |
cf5d5941 | 1068 | /* refcount was already taken, and we're keeping it */ |
a8a648c4 | 1069 | root->subsys_mask |= bit; |
a1a71b45 | 1070 | } else if (bit & removed_mask) { |
ddbcc7e8 | 1071 | /* We're removing this subsystem */ |
9871bf95 | 1072 | BUG_ON(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]); |
bd89aabc | 1073 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); |
a8a648c4 | 1074 | |
ddbcc7e8 | 1075 | if (ss->bind) |
eb95419b | 1076 | ss->bind(cgroup_dummy_top->subsys[i]); |
9871bf95 | 1077 | cgroup_dummy_top->subsys[i]->cgroup = cgroup_dummy_top; |
bd89aabc | 1078 | cgrp->subsys[i] = NULL; |
9871bf95 TH |
1079 | cgroup_subsys[i]->root = &cgroup_dummy_root; |
1080 | list_move(&ss->sibling, &cgroup_dummy_root.subsys_list); | |
a8a648c4 | 1081 | |
cf5d5941 BB |
1082 | /* subsystem is now free - drop reference on module */ |
1083 | module_put(ss->module); | |
a8a648c4 | 1084 | root->subsys_mask &= ~bit; |
ddbcc7e8 PM |
1085 | } |
1086 | } | |
ddbcc7e8 | 1087 | |
1672d040 TH |
1088 | /* |
1089 | * Mark @root has finished binding subsystems. @root->subsys_mask | |
1090 | * now matches the bound subsystems. | |
1091 | */ | |
1092 | root->flags |= CGRP_ROOT_SUBSYS_BOUND; | |
1093 | ||
ddbcc7e8 | 1094 | return 0; |
1d5be6b2 TH |
1095 | |
1096 | out_put: | |
1097 | for_each_subsys(ss, i) | |
1098 | if (pinned & (1 << i)) | |
1099 | module_put(ss->module); | |
1100 | return ret; | |
ddbcc7e8 PM |
1101 | } |
1102 | ||
34c80b1d | 1103 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) |
ddbcc7e8 | 1104 | { |
34c80b1d | 1105 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
ddbcc7e8 PM |
1106 | struct cgroup_subsys *ss; |
1107 | ||
e25e2cbb | 1108 | mutex_lock(&cgroup_root_mutex); |
5549c497 | 1109 | for_each_root_subsys(root, ss) |
ddbcc7e8 | 1110 | seq_printf(seq, ",%s", ss->name); |
873fe09e TH |
1111 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) |
1112 | seq_puts(seq, ",sane_behavior"); | |
93438629 | 1113 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1114 | seq_puts(seq, ",noprefix"); |
93438629 | 1115 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1116 | seq_puts(seq, ",xattr"); |
81a6a5cd PM |
1117 | if (strlen(root->release_agent_path)) |
1118 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
2260e7fc | 1119 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags)) |
97978e6d | 1120 | seq_puts(seq, ",clone_children"); |
c6d57f33 PM |
1121 | if (strlen(root->name)) |
1122 | seq_printf(seq, ",name=%s", root->name); | |
e25e2cbb | 1123 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1124 | return 0; |
1125 | } | |
1126 | ||
1127 | struct cgroup_sb_opts { | |
a1a71b45 | 1128 | unsigned long subsys_mask; |
ddbcc7e8 | 1129 | unsigned long flags; |
81a6a5cd | 1130 | char *release_agent; |
2260e7fc | 1131 | bool cpuset_clone_children; |
c6d57f33 | 1132 | char *name; |
2c6ab6d2 PM |
1133 | /* User explicitly requested empty subsystem */ |
1134 | bool none; | |
c6d57f33 PM |
1135 | |
1136 | struct cgroupfs_root *new_root; | |
2c6ab6d2 | 1137 | |
ddbcc7e8 PM |
1138 | }; |
1139 | ||
aae8aab4 | 1140 | /* |
9871bf95 TH |
1141 | * Convert a hierarchy specifier into a bitmask of subsystems and |
1142 | * flags. Call with cgroup_mutex held to protect the cgroup_subsys[] | |
1143 | * array. This function takes refcounts on subsystems to be used, unless it | |
1144 | * returns error, in which case no refcounts are taken. | |
aae8aab4 | 1145 | */ |
cf5d5941 | 1146 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1147 | { |
32a8cf23 DL |
1148 | char *token, *o = data; |
1149 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1150 | unsigned long mask = (unsigned long)-1; |
30159ec7 TH |
1151 | struct cgroup_subsys *ss; |
1152 | int i; | |
f9ab5b5b | 1153 | |
aae8aab4 BB |
1154 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1155 | ||
f9ab5b5b LZ |
1156 | #ifdef CONFIG_CPUSETS |
1157 | mask = ~(1UL << cpuset_subsys_id); | |
1158 | #endif | |
ddbcc7e8 | 1159 | |
c6d57f33 | 1160 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1161 | |
1162 | while ((token = strsep(&o, ",")) != NULL) { | |
1163 | if (!*token) | |
1164 | return -EINVAL; | |
32a8cf23 | 1165 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1166 | /* Explicitly have no subsystems */ |
1167 | opts->none = true; | |
32a8cf23 DL |
1168 | continue; |
1169 | } | |
1170 | if (!strcmp(token, "all")) { | |
1171 | /* Mutually exclusive option 'all' + subsystem name */ | |
1172 | if (one_ss) | |
1173 | return -EINVAL; | |
1174 | all_ss = true; | |
1175 | continue; | |
1176 | } | |
873fe09e TH |
1177 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1178 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1179 | continue; | |
1180 | } | |
32a8cf23 | 1181 | if (!strcmp(token, "noprefix")) { |
93438629 | 1182 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1183 | continue; |
1184 | } | |
1185 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1186 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1187 | continue; |
1188 | } | |
03b1cde6 | 1189 | if (!strcmp(token, "xattr")) { |
93438629 | 1190 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1191 | continue; |
1192 | } | |
32a8cf23 | 1193 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1194 | /* Specifying two release agents is forbidden */ |
1195 | if (opts->release_agent) | |
1196 | return -EINVAL; | |
c6d57f33 | 1197 | opts->release_agent = |
e400c285 | 1198 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1199 | if (!opts->release_agent) |
1200 | return -ENOMEM; | |
32a8cf23 DL |
1201 | continue; |
1202 | } | |
1203 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1204 | const char *name = token + 5; |
1205 | /* Can't specify an empty name */ | |
1206 | if (!strlen(name)) | |
1207 | return -EINVAL; | |
1208 | /* Must match [\w.-]+ */ | |
1209 | for (i = 0; i < strlen(name); i++) { | |
1210 | char c = name[i]; | |
1211 | if (isalnum(c)) | |
1212 | continue; | |
1213 | if ((c == '.') || (c == '-') || (c == '_')) | |
1214 | continue; | |
1215 | return -EINVAL; | |
1216 | } | |
1217 | /* Specifying two names is forbidden */ | |
1218 | if (opts->name) | |
1219 | return -EINVAL; | |
1220 | opts->name = kstrndup(name, | |
e400c285 | 1221 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1222 | GFP_KERNEL); |
1223 | if (!opts->name) | |
1224 | return -ENOMEM; | |
32a8cf23 DL |
1225 | |
1226 | continue; | |
1227 | } | |
1228 | ||
30159ec7 | 1229 | for_each_subsys(ss, i) { |
32a8cf23 DL |
1230 | if (strcmp(token, ss->name)) |
1231 | continue; | |
1232 | if (ss->disabled) | |
1233 | continue; | |
1234 | ||
1235 | /* Mutually exclusive option 'all' + subsystem name */ | |
1236 | if (all_ss) | |
1237 | return -EINVAL; | |
a1a71b45 | 1238 | set_bit(i, &opts->subsys_mask); |
32a8cf23 DL |
1239 | one_ss = true; |
1240 | ||
1241 | break; | |
1242 | } | |
1243 | if (i == CGROUP_SUBSYS_COUNT) | |
1244 | return -ENOENT; | |
1245 | } | |
1246 | ||
1247 | /* | |
1248 | * If the 'all' option was specified select all the subsystems, | |
0d19ea86 LZ |
1249 | * otherwise if 'none', 'name=' and a subsystem name options |
1250 | * were not specified, let's default to 'all' | |
32a8cf23 | 1251 | */ |
30159ec7 TH |
1252 | if (all_ss || (!one_ss && !opts->none && !opts->name)) |
1253 | for_each_subsys(ss, i) | |
1254 | if (!ss->disabled) | |
1255 | set_bit(i, &opts->subsys_mask); | |
ddbcc7e8 | 1256 | |
2c6ab6d2 PM |
1257 | /* Consistency checks */ |
1258 | ||
873fe09e TH |
1259 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1260 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); | |
1261 | ||
1262 | if (opts->flags & CGRP_ROOT_NOPREFIX) { | |
1263 | pr_err("cgroup: sane_behavior: noprefix is not allowed\n"); | |
1264 | return -EINVAL; | |
1265 | } | |
1266 | ||
1267 | if (opts->cpuset_clone_children) { | |
1268 | pr_err("cgroup: sane_behavior: clone_children is not allowed\n"); | |
1269 | return -EINVAL; | |
1270 | } | |
1271 | } | |
1272 | ||
f9ab5b5b LZ |
1273 | /* |
1274 | * Option noprefix was introduced just for backward compatibility | |
1275 | * with the old cpuset, so we allow noprefix only if mounting just | |
1276 | * the cpuset subsystem. | |
1277 | */ | |
93438629 | 1278 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1279 | return -EINVAL; |
1280 | ||
2c6ab6d2 PM |
1281 | |
1282 | /* Can't specify "none" and some subsystems */ | |
a1a71b45 | 1283 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1284 | return -EINVAL; |
1285 | ||
1286 | /* | |
1287 | * We either have to specify by name or by subsystems. (So all | |
1288 | * empty hierarchies must have a name). | |
1289 | */ | |
a1a71b45 | 1290 | if (!opts->subsys_mask && !opts->name) |
ddbcc7e8 PM |
1291 | return -EINVAL; |
1292 | ||
1293 | return 0; | |
1294 | } | |
1295 | ||
1296 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) | |
1297 | { | |
1298 | int ret = 0; | |
1299 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1300 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1301 | struct cgroup_sb_opts opts; |
a1a71b45 | 1302 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1303 | |
873fe09e TH |
1304 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1305 | pr_err("cgroup: sane_behavior: remount is not allowed\n"); | |
1306 | return -EINVAL; | |
1307 | } | |
1308 | ||
bd89aabc | 1309 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1310 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1311 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1312 | |
1313 | /* See what subsystems are wanted */ | |
1314 | ret = parse_cgroupfs_options(data, &opts); | |
1315 | if (ret) | |
1316 | goto out_unlock; | |
1317 | ||
a8a648c4 | 1318 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
8b5a5a9d TH |
1319 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", |
1320 | task_tgid_nr(current), current->comm); | |
1321 | ||
a1a71b45 AR |
1322 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1323 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1324 | |
cf5d5941 | 1325 | /* Don't allow flags or name to change at remount */ |
0ce6cba3 | 1326 | if (((opts.flags ^ root->flags) & CGRP_ROOT_OPTION_MASK) || |
cf5d5941 | 1327 | (opts.name && strcmp(opts.name, root->name))) { |
0ce6cba3 TH |
1328 | pr_err("cgroup: option or name mismatch, new: 0x%lx \"%s\", old: 0x%lx \"%s\"\n", |
1329 | opts.flags & CGRP_ROOT_OPTION_MASK, opts.name ?: "", | |
1330 | root->flags & CGRP_ROOT_OPTION_MASK, root->name); | |
c6d57f33 PM |
1331 | ret = -EINVAL; |
1332 | goto out_unlock; | |
1333 | } | |
1334 | ||
f172e67c TH |
1335 | /* remounting is not allowed for populated hierarchies */ |
1336 | if (root->number_of_cgroups > 1) { | |
1337 | ret = -EBUSY; | |
1338 | goto out_unlock; | |
1339 | } | |
1340 | ||
a8a648c4 | 1341 | ret = rebind_subsystems(root, added_mask, removed_mask); |
3126121f | 1342 | if (ret) |
0670e08b | 1343 | goto out_unlock; |
ddbcc7e8 | 1344 | |
81a6a5cd PM |
1345 | if (opts.release_agent) |
1346 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 1347 | out_unlock: |
66bdc9cf | 1348 | kfree(opts.release_agent); |
c6d57f33 | 1349 | kfree(opts.name); |
e25e2cbb | 1350 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1351 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 1352 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1353 | return ret; |
1354 | } | |
1355 | ||
b87221de | 1356 | static const struct super_operations cgroup_ops = { |
ddbcc7e8 PM |
1357 | .statfs = simple_statfs, |
1358 | .drop_inode = generic_delete_inode, | |
1359 | .show_options = cgroup_show_options, | |
1360 | .remount_fs = cgroup_remount, | |
1361 | }; | |
1362 | ||
cc31edce PM |
1363 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1364 | { | |
1365 | INIT_LIST_HEAD(&cgrp->sibling); | |
1366 | INIT_LIST_HEAD(&cgrp->children); | |
05ef1d7c | 1367 | INIT_LIST_HEAD(&cgrp->files); |
69d0206c | 1368 | INIT_LIST_HEAD(&cgrp->cset_links); |
cc31edce | 1369 | INIT_LIST_HEAD(&cgrp->release_list); |
72a8cb30 BB |
1370 | INIT_LIST_HEAD(&cgrp->pidlists); |
1371 | mutex_init(&cgrp->pidlist_mutex); | |
67f4c36f | 1372 | cgrp->dummy_css.cgroup = cgrp; |
0dea1168 KS |
1373 | INIT_LIST_HEAD(&cgrp->event_list); |
1374 | spin_lock_init(&cgrp->event_list_lock); | |
03b1cde6 | 1375 | simple_xattrs_init(&cgrp->xattrs); |
cc31edce | 1376 | } |
c6d57f33 | 1377 | |
ddbcc7e8 PM |
1378 | static void init_cgroup_root(struct cgroupfs_root *root) |
1379 | { | |
bd89aabc | 1380 | struct cgroup *cgrp = &root->top_cgroup; |
b0ca5a84 | 1381 | |
ddbcc7e8 PM |
1382 | INIT_LIST_HEAD(&root->subsys_list); |
1383 | INIT_LIST_HEAD(&root->root_list); | |
1384 | root->number_of_cgroups = 1; | |
bd89aabc | 1385 | cgrp->root = root; |
a4ea1cc9 | 1386 | RCU_INIT_POINTER(cgrp->name, &root_cgroup_name); |
cc31edce | 1387 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1388 | idr_init(&root->cgroup_idr); |
ddbcc7e8 PM |
1389 | } |
1390 | ||
fc76df70 | 1391 | static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end) |
2c6ab6d2 | 1392 | { |
1a574231 | 1393 | int id; |
2c6ab6d2 | 1394 | |
54e7b4eb TH |
1395 | lockdep_assert_held(&cgroup_mutex); |
1396 | lockdep_assert_held(&cgroup_root_mutex); | |
1397 | ||
fc76df70 TH |
1398 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end, |
1399 | GFP_KERNEL); | |
1a574231 TH |
1400 | if (id < 0) |
1401 | return id; | |
1402 | ||
1403 | root->hierarchy_id = id; | |
fa3ca07e TH |
1404 | return 0; |
1405 | } | |
1406 | ||
1407 | static void cgroup_exit_root_id(struct cgroupfs_root *root) | |
1408 | { | |
54e7b4eb TH |
1409 | lockdep_assert_held(&cgroup_mutex); |
1410 | lockdep_assert_held(&cgroup_root_mutex); | |
1411 | ||
fa3ca07e | 1412 | if (root->hierarchy_id) { |
1a574231 | 1413 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); |
fa3ca07e TH |
1414 | root->hierarchy_id = 0; |
1415 | } | |
2c6ab6d2 PM |
1416 | } |
1417 | ||
ddbcc7e8 PM |
1418 | static int cgroup_test_super(struct super_block *sb, void *data) |
1419 | { | |
c6d57f33 | 1420 | struct cgroup_sb_opts *opts = data; |
ddbcc7e8 PM |
1421 | struct cgroupfs_root *root = sb->s_fs_info; |
1422 | ||
c6d57f33 PM |
1423 | /* If we asked for a name then it must match */ |
1424 | if (opts->name && strcmp(opts->name, root->name)) | |
1425 | return 0; | |
ddbcc7e8 | 1426 | |
2c6ab6d2 PM |
1427 | /* |
1428 | * If we asked for subsystems (or explicitly for no | |
1429 | * subsystems) then they must match | |
1430 | */ | |
a1a71b45 AR |
1431 | if ((opts->subsys_mask || opts->none) |
1432 | && (opts->subsys_mask != root->subsys_mask)) | |
ddbcc7e8 PM |
1433 | return 0; |
1434 | ||
1435 | return 1; | |
1436 | } | |
1437 | ||
c6d57f33 PM |
1438 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1439 | { | |
1440 | struct cgroupfs_root *root; | |
1441 | ||
a1a71b45 | 1442 | if (!opts->subsys_mask && !opts->none) |
c6d57f33 PM |
1443 | return NULL; |
1444 | ||
1445 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1446 | if (!root) | |
1447 | return ERR_PTR(-ENOMEM); | |
1448 | ||
1449 | init_cgroup_root(root); | |
2c6ab6d2 | 1450 | |
1672d040 TH |
1451 | /* |
1452 | * We need to set @root->subsys_mask now so that @root can be | |
1453 | * matched by cgroup_test_super() before it finishes | |
1454 | * initialization; otherwise, competing mounts with the same | |
1455 | * options may try to bind the same subsystems instead of waiting | |
1456 | * for the first one leading to unexpected mount errors. | |
1457 | * SUBSYS_BOUND will be set once actual binding is complete. | |
1458 | */ | |
a1a71b45 | 1459 | root->subsys_mask = opts->subsys_mask; |
c6d57f33 PM |
1460 | root->flags = opts->flags; |
1461 | if (opts->release_agent) | |
1462 | strcpy(root->release_agent_path, opts->release_agent); | |
1463 | if (opts->name) | |
1464 | strcpy(root->name, opts->name); | |
2260e7fc TH |
1465 | if (opts->cpuset_clone_children) |
1466 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1467 | return root; |
1468 | } | |
1469 | ||
fa3ca07e | 1470 | static void cgroup_free_root(struct cgroupfs_root *root) |
2c6ab6d2 | 1471 | { |
fa3ca07e TH |
1472 | if (root) { |
1473 | /* hierarhcy ID shoulid already have been released */ | |
1474 | WARN_ON_ONCE(root->hierarchy_id); | |
2c6ab6d2 | 1475 | |
4e96ee8e | 1476 | idr_destroy(&root->cgroup_idr); |
fa3ca07e TH |
1477 | kfree(root); |
1478 | } | |
2c6ab6d2 PM |
1479 | } |
1480 | ||
ddbcc7e8 PM |
1481 | static int cgroup_set_super(struct super_block *sb, void *data) |
1482 | { | |
1483 | int ret; | |
c6d57f33 PM |
1484 | struct cgroup_sb_opts *opts = data; |
1485 | ||
1486 | /* If we don't have a new root, we can't set up a new sb */ | |
1487 | if (!opts->new_root) | |
1488 | return -EINVAL; | |
1489 | ||
a1a71b45 | 1490 | BUG_ON(!opts->subsys_mask && !opts->none); |
ddbcc7e8 PM |
1491 | |
1492 | ret = set_anon_super(sb, NULL); | |
1493 | if (ret) | |
1494 | return ret; | |
1495 | ||
c6d57f33 PM |
1496 | sb->s_fs_info = opts->new_root; |
1497 | opts->new_root->sb = sb; | |
ddbcc7e8 PM |
1498 | |
1499 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1500 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1501 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1502 | sb->s_op = &cgroup_ops; | |
1503 | ||
1504 | return 0; | |
1505 | } | |
1506 | ||
1507 | static int cgroup_get_rootdir(struct super_block *sb) | |
1508 | { | |
0df6a63f AV |
1509 | static const struct dentry_operations cgroup_dops = { |
1510 | .d_iput = cgroup_diput, | |
c72a04e3 | 1511 | .d_delete = cgroup_delete, |
0df6a63f AV |
1512 | }; |
1513 | ||
ddbcc7e8 PM |
1514 | struct inode *inode = |
1515 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
ddbcc7e8 PM |
1516 | |
1517 | if (!inode) | |
1518 | return -ENOMEM; | |
1519 | ||
ddbcc7e8 PM |
1520 | inode->i_fop = &simple_dir_operations; |
1521 | inode->i_op = &cgroup_dir_inode_operations; | |
1522 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1523 | inc_nlink(inode); | |
48fde701 AV |
1524 | sb->s_root = d_make_root(inode); |
1525 | if (!sb->s_root) | |
ddbcc7e8 | 1526 | return -ENOMEM; |
0df6a63f AV |
1527 | /* for everything else we want ->d_op set */ |
1528 | sb->s_d_op = &cgroup_dops; | |
ddbcc7e8 PM |
1529 | return 0; |
1530 | } | |
1531 | ||
f7e83571 | 1532 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1533 | int flags, const char *unused_dev_name, |
f7e83571 | 1534 | void *data) |
ddbcc7e8 PM |
1535 | { |
1536 | struct cgroup_sb_opts opts; | |
c6d57f33 | 1537 | struct cgroupfs_root *root; |
ddbcc7e8 PM |
1538 | int ret = 0; |
1539 | struct super_block *sb; | |
c6d57f33 | 1540 | struct cgroupfs_root *new_root; |
3126121f | 1541 | struct list_head tmp_links; |
e25e2cbb | 1542 | struct inode *inode; |
3126121f | 1543 | const struct cred *cred; |
ddbcc7e8 PM |
1544 | |
1545 | /* First find the desired set of subsystems */ | |
aae8aab4 | 1546 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1547 | ret = parse_cgroupfs_options(data, &opts); |
aae8aab4 | 1548 | mutex_unlock(&cgroup_mutex); |
c6d57f33 PM |
1549 | if (ret) |
1550 | goto out_err; | |
ddbcc7e8 | 1551 | |
c6d57f33 PM |
1552 | /* |
1553 | * Allocate a new cgroup root. We may not need it if we're | |
1554 | * reusing an existing hierarchy. | |
1555 | */ | |
1556 | new_root = cgroup_root_from_opts(&opts); | |
1557 | if (IS_ERR(new_root)) { | |
1558 | ret = PTR_ERR(new_root); | |
1d5be6b2 | 1559 | goto out_err; |
81a6a5cd | 1560 | } |
c6d57f33 | 1561 | opts.new_root = new_root; |
ddbcc7e8 | 1562 | |
c6d57f33 | 1563 | /* Locate an existing or new sb for this hierarchy */ |
9249e17f | 1564 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); |
ddbcc7e8 | 1565 | if (IS_ERR(sb)) { |
c6d57f33 | 1566 | ret = PTR_ERR(sb); |
fa3ca07e | 1567 | cgroup_free_root(opts.new_root); |
1d5be6b2 | 1568 | goto out_err; |
ddbcc7e8 PM |
1569 | } |
1570 | ||
c6d57f33 PM |
1571 | root = sb->s_fs_info; |
1572 | BUG_ON(!root); | |
1573 | if (root == opts.new_root) { | |
1574 | /* We used the new root structure, so this is a new hierarchy */ | |
c12f65d4 | 1575 | struct cgroup *root_cgrp = &root->top_cgroup; |
c6d57f33 | 1576 | struct cgroupfs_root *existing_root; |
28fd5dfc | 1577 | int i; |
5abb8855 | 1578 | struct css_set *cset; |
ddbcc7e8 PM |
1579 | |
1580 | BUG_ON(sb->s_root != NULL); | |
1581 | ||
1582 | ret = cgroup_get_rootdir(sb); | |
1583 | if (ret) | |
1584 | goto drop_new_super; | |
817929ec | 1585 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1586 | |
817929ec | 1587 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 | 1588 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1589 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 | 1590 | |
4e96ee8e LZ |
1591 | root_cgrp->id = idr_alloc(&root->cgroup_idr, root_cgrp, |
1592 | 0, 1, GFP_KERNEL); | |
1593 | if (root_cgrp->id < 0) | |
1594 | goto unlock_drop; | |
1595 | ||
e25e2cbb TH |
1596 | /* Check for name clashes with existing mounts */ |
1597 | ret = -EBUSY; | |
1598 | if (strlen(root->name)) | |
1599 | for_each_active_root(existing_root) | |
1600 | if (!strcmp(existing_root->name, root->name)) | |
1601 | goto unlock_drop; | |
c6d57f33 | 1602 | |
817929ec PM |
1603 | /* |
1604 | * We're accessing css_set_count without locking | |
1605 | * css_set_lock here, but that's OK - it can only be | |
1606 | * increased by someone holding cgroup_lock, and | |
1607 | * that's us. The worst that can happen is that we | |
1608 | * have some link structures left over | |
1609 | */ | |
69d0206c | 1610 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); |
e25e2cbb TH |
1611 | if (ret) |
1612 | goto unlock_drop; | |
817929ec | 1613 | |
fc76df70 TH |
1614 | /* ID 0 is reserved for dummy root, 1 for unified hierarchy */ |
1615 | ret = cgroup_init_root_id(root, 2, 0); | |
fa3ca07e TH |
1616 | if (ret) |
1617 | goto unlock_drop; | |
1618 | ||
3126121f TH |
1619 | sb->s_root->d_fsdata = root_cgrp; |
1620 | root_cgrp->dentry = sb->s_root; | |
1621 | ||
1622 | /* | |
1623 | * We're inside get_sb() and will call lookup_one_len() to | |
1624 | * create the root files, which doesn't work if SELinux is | |
1625 | * in use. The following cred dancing somehow works around | |
1626 | * it. See 2ce9738ba ("cgroupfs: use init_cred when | |
1627 | * populating new cgroupfs mount") for more details. | |
1628 | */ | |
1629 | cred = override_creds(&init_cred); | |
1630 | ||
2bb566cb | 1631 | ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true); |
3126121f TH |
1632 | if (ret) |
1633 | goto rm_base_files; | |
1634 | ||
a8a648c4 | 1635 | ret = rebind_subsystems(root, root->subsys_mask, 0); |
3126121f TH |
1636 | if (ret) |
1637 | goto rm_base_files; | |
1638 | ||
1639 | revert_creds(cred); | |
1640 | ||
cf5d5941 BB |
1641 | /* |
1642 | * There must be no failure case after here, since rebinding | |
1643 | * takes care of subsystems' refcounts, which are explicitly | |
1644 | * dropped in the failure exit path. | |
1645 | */ | |
ddbcc7e8 | 1646 | |
9871bf95 TH |
1647 | list_add(&root->root_list, &cgroup_roots); |
1648 | cgroup_root_count++; | |
ddbcc7e8 | 1649 | |
817929ec PM |
1650 | /* Link the top cgroup in this hierarchy into all |
1651 | * the css_set objects */ | |
1652 | write_lock(&css_set_lock); | |
5abb8855 | 1653 | hash_for_each(css_set_table, i, cset, hlist) |
69d0206c | 1654 | link_css_set(&tmp_links, cset, root_cgrp); |
817929ec PM |
1655 | write_unlock(&css_set_lock); |
1656 | ||
69d0206c | 1657 | free_cgrp_cset_links(&tmp_links); |
817929ec | 1658 | |
c12f65d4 | 1659 | BUG_ON(!list_empty(&root_cgrp->children)); |
ddbcc7e8 PM |
1660 | BUG_ON(root->number_of_cgroups != 1); |
1661 | ||
e25e2cbb | 1662 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1663 | mutex_unlock(&cgroup_mutex); |
34f77a90 | 1664 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1665 | } else { |
1666 | /* | |
1667 | * We re-used an existing hierarchy - the new root (if | |
1668 | * any) is not needed | |
1669 | */ | |
fa3ca07e | 1670 | cgroup_free_root(opts.new_root); |
873fe09e | 1671 | |
c7ba8287 | 1672 | if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) { |
2a0ff3fb JL |
1673 | if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { |
1674 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); | |
1675 | ret = -EINVAL; | |
1676 | goto drop_new_super; | |
1677 | } else { | |
1678 | pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); | |
1679 | } | |
873fe09e | 1680 | } |
ddbcc7e8 PM |
1681 | } |
1682 | ||
c6d57f33 PM |
1683 | kfree(opts.release_agent); |
1684 | kfree(opts.name); | |
f7e83571 | 1685 | return dget(sb->s_root); |
ddbcc7e8 | 1686 | |
3126121f TH |
1687 | rm_base_files: |
1688 | free_cgrp_cset_links(&tmp_links); | |
2bb566cb | 1689 | cgroup_addrm_files(&root->top_cgroup, cgroup_base_files, false); |
3126121f | 1690 | revert_creds(cred); |
e25e2cbb | 1691 | unlock_drop: |
fa3ca07e | 1692 | cgroup_exit_root_id(root); |
e25e2cbb TH |
1693 | mutex_unlock(&cgroup_root_mutex); |
1694 | mutex_unlock(&cgroup_mutex); | |
1695 | mutex_unlock(&inode->i_mutex); | |
ddbcc7e8 | 1696 | drop_new_super: |
6f5bbff9 | 1697 | deactivate_locked_super(sb); |
c6d57f33 PM |
1698 | out_err: |
1699 | kfree(opts.release_agent); | |
1700 | kfree(opts.name); | |
f7e83571 | 1701 | return ERR_PTR(ret); |
ddbcc7e8 PM |
1702 | } |
1703 | ||
1704 | static void cgroup_kill_sb(struct super_block *sb) { | |
1705 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1706 | struct cgroup *cgrp = &root->top_cgroup; |
69d0206c | 1707 | struct cgrp_cset_link *link, *tmp_link; |
ddbcc7e8 PM |
1708 | int ret; |
1709 | ||
1710 | BUG_ON(!root); | |
1711 | ||
1712 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc | 1713 | BUG_ON(!list_empty(&cgrp->children)); |
ddbcc7e8 | 1714 | |
3126121f | 1715 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1716 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1717 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1718 | |
1719 | /* Rebind all subsystems back to the default hierarchy */ | |
1672d040 TH |
1720 | if (root->flags & CGRP_ROOT_SUBSYS_BOUND) { |
1721 | ret = rebind_subsystems(root, 0, root->subsys_mask); | |
1722 | /* Shouldn't be able to fail ... */ | |
1723 | BUG_ON(ret); | |
1724 | } | |
ddbcc7e8 | 1725 | |
817929ec | 1726 | /* |
69d0206c | 1727 | * Release all the links from cset_links to this hierarchy's |
817929ec PM |
1728 | * root cgroup |
1729 | */ | |
1730 | write_lock(&css_set_lock); | |
71cbb949 | 1731 | |
69d0206c TH |
1732 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { |
1733 | list_del(&link->cset_link); | |
1734 | list_del(&link->cgrp_link); | |
817929ec PM |
1735 | kfree(link); |
1736 | } | |
1737 | write_unlock(&css_set_lock); | |
1738 | ||
839ec545 PM |
1739 | if (!list_empty(&root->root_list)) { |
1740 | list_del(&root->root_list); | |
9871bf95 | 1741 | cgroup_root_count--; |
839ec545 | 1742 | } |
e5f6a860 | 1743 | |
fa3ca07e TH |
1744 | cgroup_exit_root_id(root); |
1745 | ||
e25e2cbb | 1746 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1747 | mutex_unlock(&cgroup_mutex); |
3126121f | 1748 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1749 | |
03b1cde6 AR |
1750 | simple_xattrs_free(&cgrp->xattrs); |
1751 | ||
ddbcc7e8 | 1752 | kill_litter_super(sb); |
fa3ca07e | 1753 | cgroup_free_root(root); |
ddbcc7e8 PM |
1754 | } |
1755 | ||
1756 | static struct file_system_type cgroup_fs_type = { | |
1757 | .name = "cgroup", | |
f7e83571 | 1758 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1759 | .kill_sb = cgroup_kill_sb, |
1760 | }; | |
1761 | ||
676db4af GK |
1762 | static struct kobject *cgroup_kobj; |
1763 | ||
a043e3b2 LZ |
1764 | /** |
1765 | * cgroup_path - generate the path of a cgroup | |
1766 | * @cgrp: the cgroup in question | |
1767 | * @buf: the buffer to write the path into | |
1768 | * @buflen: the length of the buffer | |
1769 | * | |
65dff759 LZ |
1770 | * Writes path of cgroup into buf. Returns 0 on success, -errno on error. |
1771 | * | |
1772 | * We can't generate cgroup path using dentry->d_name, as accessing | |
1773 | * dentry->name must be protected by irq-unsafe dentry->d_lock or parent | |
1774 | * inode's i_mutex, while on the other hand cgroup_path() can be called | |
1775 | * with some irq-safe spinlocks held. | |
ddbcc7e8 | 1776 | */ |
bd89aabc | 1777 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 | 1778 | { |
65dff759 | 1779 | int ret = -ENAMETOOLONG; |
ddbcc7e8 | 1780 | char *start; |
febfcef6 | 1781 | |
da1f296f TH |
1782 | if (!cgrp->parent) { |
1783 | if (strlcpy(buf, "/", buflen) >= buflen) | |
1784 | return -ENAMETOOLONG; | |
ddbcc7e8 PM |
1785 | return 0; |
1786 | } | |
1787 | ||
316eb661 | 1788 | start = buf + buflen - 1; |
316eb661 | 1789 | *start = '\0'; |
9a9686b6 | 1790 | |
65dff759 | 1791 | rcu_read_lock(); |
da1f296f | 1792 | do { |
65dff759 LZ |
1793 | const char *name = cgroup_name(cgrp); |
1794 | int len; | |
1795 | ||
1796 | len = strlen(name); | |
ddbcc7e8 | 1797 | if ((start -= len) < buf) |
65dff759 LZ |
1798 | goto out; |
1799 | memcpy(start, name, len); | |
9a9686b6 | 1800 | |
ddbcc7e8 | 1801 | if (--start < buf) |
65dff759 | 1802 | goto out; |
ddbcc7e8 | 1803 | *start = '/'; |
65dff759 LZ |
1804 | |
1805 | cgrp = cgrp->parent; | |
da1f296f | 1806 | } while (cgrp->parent); |
65dff759 | 1807 | ret = 0; |
ddbcc7e8 | 1808 | memmove(buf, start, buf + buflen - start); |
65dff759 LZ |
1809 | out: |
1810 | rcu_read_unlock(); | |
1811 | return ret; | |
ddbcc7e8 | 1812 | } |
67523c48 | 1813 | EXPORT_SYMBOL_GPL(cgroup_path); |
ddbcc7e8 | 1814 | |
857a2beb | 1815 | /** |
913ffdb5 | 1816 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 1817 | * @task: target task |
857a2beb TH |
1818 | * @buf: the buffer to write the path into |
1819 | * @buflen: the length of the buffer | |
1820 | * | |
913ffdb5 TH |
1821 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
1822 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
1823 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
1824 | * cgroup controller callbacks. | |
1825 | * | |
1826 | * Returns 0 on success, fails with -%ENAMETOOLONG if @buflen is too short. | |
857a2beb | 1827 | */ |
913ffdb5 | 1828 | int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb TH |
1829 | { |
1830 | struct cgroupfs_root *root; | |
913ffdb5 TH |
1831 | struct cgroup *cgrp; |
1832 | int hierarchy_id = 1, ret = 0; | |
1833 | ||
1834 | if (buflen < 2) | |
1835 | return -ENAMETOOLONG; | |
857a2beb TH |
1836 | |
1837 | mutex_lock(&cgroup_mutex); | |
1838 | ||
913ffdb5 TH |
1839 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
1840 | ||
857a2beb TH |
1841 | if (root) { |
1842 | cgrp = task_cgroup_from_root(task, root); | |
1843 | ret = cgroup_path(cgrp, buf, buflen); | |
913ffdb5 TH |
1844 | } else { |
1845 | /* if no hierarchy exists, everyone is in "/" */ | |
1846 | memcpy(buf, "/", 2); | |
857a2beb TH |
1847 | } |
1848 | ||
1849 | mutex_unlock(&cgroup_mutex); | |
857a2beb TH |
1850 | return ret; |
1851 | } | |
913ffdb5 | 1852 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 1853 | |
2f7ee569 TH |
1854 | /* |
1855 | * Control Group taskset | |
1856 | */ | |
134d3373 TH |
1857 | struct task_and_cgroup { |
1858 | struct task_struct *task; | |
1859 | struct cgroup *cgrp; | |
6f4b7e63 | 1860 | struct css_set *cset; |
134d3373 TH |
1861 | }; |
1862 | ||
2f7ee569 TH |
1863 | struct cgroup_taskset { |
1864 | struct task_and_cgroup single; | |
1865 | struct flex_array *tc_array; | |
1866 | int tc_array_len; | |
1867 | int idx; | |
1868 | struct cgroup *cur_cgrp; | |
1869 | }; | |
1870 | ||
1871 | /** | |
1872 | * cgroup_taskset_first - reset taskset and return the first task | |
1873 | * @tset: taskset of interest | |
1874 | * | |
1875 | * @tset iteration is initialized and the first task is returned. | |
1876 | */ | |
1877 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1878 | { | |
1879 | if (tset->tc_array) { | |
1880 | tset->idx = 0; | |
1881 | return cgroup_taskset_next(tset); | |
1882 | } else { | |
1883 | tset->cur_cgrp = tset->single.cgrp; | |
1884 | return tset->single.task; | |
1885 | } | |
1886 | } | |
1887 | EXPORT_SYMBOL_GPL(cgroup_taskset_first); | |
1888 | ||
1889 | /** | |
1890 | * cgroup_taskset_next - iterate to the next task in taskset | |
1891 | * @tset: taskset of interest | |
1892 | * | |
1893 | * Return the next task in @tset. Iteration must have been initialized | |
1894 | * with cgroup_taskset_first(). | |
1895 | */ | |
1896 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1897 | { | |
1898 | struct task_and_cgroup *tc; | |
1899 | ||
1900 | if (!tset->tc_array || tset->idx >= tset->tc_array_len) | |
1901 | return NULL; | |
1902 | ||
1903 | tc = flex_array_get(tset->tc_array, tset->idx++); | |
1904 | tset->cur_cgrp = tc->cgrp; | |
1905 | return tc->task; | |
1906 | } | |
1907 | EXPORT_SYMBOL_GPL(cgroup_taskset_next); | |
1908 | ||
1909 | /** | |
1910 | * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task | |
1911 | * @tset: taskset of interest | |
1912 | * | |
1913 | * Return the cgroup for the current (last returned) task of @tset. This | |
1914 | * function must be preceded by either cgroup_taskset_first() or | |
1915 | * cgroup_taskset_next(). | |
1916 | */ | |
1917 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) | |
1918 | { | |
1919 | return tset->cur_cgrp; | |
1920 | } | |
1921 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); | |
1922 | ||
1923 | /** | |
1924 | * cgroup_taskset_size - return the number of tasks in taskset | |
1925 | * @tset: taskset of interest | |
1926 | */ | |
1927 | int cgroup_taskset_size(struct cgroup_taskset *tset) | |
1928 | { | |
1929 | return tset->tc_array ? tset->tc_array_len : 1; | |
1930 | } | |
1931 | EXPORT_SYMBOL_GPL(cgroup_taskset_size); | |
1932 | ||
1933 | ||
74a1166d BB |
1934 | /* |
1935 | * cgroup_task_migrate - move a task from one cgroup to another. | |
1936 | * | |
d0b2fdd2 | 1937 | * Must be called with cgroup_mutex and threadgroup locked. |
74a1166d | 1938 | */ |
5abb8855 TH |
1939 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
1940 | struct task_struct *tsk, | |
1941 | struct css_set *new_cset) | |
74a1166d | 1942 | { |
5abb8855 | 1943 | struct css_set *old_cset; |
74a1166d BB |
1944 | |
1945 | /* | |
026085ef MSB |
1946 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1947 | * setting such that we can't race against cgroup_exit() changing the | |
1948 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1949 | */ |
c84cdf75 | 1950 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 1951 | old_cset = task_css_set(tsk); |
74a1166d | 1952 | |
74a1166d | 1953 | task_lock(tsk); |
5abb8855 | 1954 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d BB |
1955 | task_unlock(tsk); |
1956 | ||
1957 | /* Update the css_set linked lists if we're using them */ | |
1958 | write_lock(&css_set_lock); | |
1959 | if (!list_empty(&tsk->cg_list)) | |
5abb8855 | 1960 | list_move(&tsk->cg_list, &new_cset->tasks); |
74a1166d BB |
1961 | write_unlock(&css_set_lock); |
1962 | ||
1963 | /* | |
5abb8855 TH |
1964 | * We just gained a reference on old_cset by taking it from the |
1965 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
1966 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 1967 | */ |
5abb8855 TH |
1968 | set_bit(CGRP_RELEASABLE, &old_cgrp->flags); |
1969 | put_css_set(old_cset); | |
74a1166d BB |
1970 | } |
1971 | ||
a043e3b2 | 1972 | /** |
081aa458 | 1973 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup |
74a1166d | 1974 | * @cgrp: the cgroup to attach to |
081aa458 LZ |
1975 | * @tsk: the task or the leader of the threadgroup to be attached |
1976 | * @threadgroup: attach the whole threadgroup? | |
74a1166d | 1977 | * |
257058ae | 1978 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take |
081aa458 | 1979 | * task_lock of @tsk or each thread in the threadgroup individually in turn. |
74a1166d | 1980 | */ |
47cfcd09 TH |
1981 | static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, |
1982 | bool threadgroup) | |
74a1166d BB |
1983 | { |
1984 | int retval, i, group_size; | |
1985 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
74a1166d BB |
1986 | struct cgroupfs_root *root = cgrp->root; |
1987 | /* threadgroup list cursor and array */ | |
081aa458 | 1988 | struct task_struct *leader = tsk; |
134d3373 | 1989 | struct task_and_cgroup *tc; |
d846687d | 1990 | struct flex_array *group; |
2f7ee569 | 1991 | struct cgroup_taskset tset = { }; |
74a1166d BB |
1992 | |
1993 | /* | |
1994 | * step 0: in order to do expensive, possibly blocking operations for | |
1995 | * every thread, we cannot iterate the thread group list, since it needs | |
1996 | * rcu or tasklist locked. instead, build an array of all threads in the | |
257058ae TH |
1997 | * group - group_rwsem prevents new threads from appearing, and if |
1998 | * threads exit, this will just be an over-estimate. | |
74a1166d | 1999 | */ |
081aa458 LZ |
2000 | if (threadgroup) |
2001 | group_size = get_nr_threads(tsk); | |
2002 | else | |
2003 | group_size = 1; | |
d846687d | 2004 | /* flex_array supports very large thread-groups better than kmalloc. */ |
134d3373 | 2005 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); |
74a1166d BB |
2006 | if (!group) |
2007 | return -ENOMEM; | |
d846687d | 2008 | /* pre-allocate to guarantee space while iterating in rcu read-side. */ |
3ac1707a | 2009 | retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); |
d846687d BB |
2010 | if (retval) |
2011 | goto out_free_group_list; | |
74a1166d | 2012 | |
74a1166d | 2013 | i = 0; |
fb5d2b4c MSB |
2014 | /* |
2015 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2016 | * already PF_EXITING could be freed from underneath us unless we | |
2017 | * take an rcu_read_lock. | |
2018 | */ | |
2019 | rcu_read_lock(); | |
74a1166d | 2020 | do { |
134d3373 TH |
2021 | struct task_and_cgroup ent; |
2022 | ||
cd3d0952 TH |
2023 | /* @tsk either already exited or can't exit until the end */ |
2024 | if (tsk->flags & PF_EXITING) | |
2025 | continue; | |
2026 | ||
74a1166d BB |
2027 | /* as per above, nr_threads may decrease, but not increase. */ |
2028 | BUG_ON(i >= group_size); | |
134d3373 TH |
2029 | ent.task = tsk; |
2030 | ent.cgrp = task_cgroup_from_root(tsk, root); | |
892a2b90 MSB |
2031 | /* nothing to do if this task is already in the cgroup */ |
2032 | if (ent.cgrp == cgrp) | |
2033 | continue; | |
61d1d219 MSB |
2034 | /* |
2035 | * saying GFP_ATOMIC has no effect here because we did prealloc | |
2036 | * earlier, but it's good form to communicate our expectations. | |
2037 | */ | |
134d3373 | 2038 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC); |
d846687d | 2039 | BUG_ON(retval != 0); |
74a1166d | 2040 | i++; |
081aa458 LZ |
2041 | |
2042 | if (!threadgroup) | |
2043 | break; | |
74a1166d | 2044 | } while_each_thread(leader, tsk); |
fb5d2b4c | 2045 | rcu_read_unlock(); |
74a1166d BB |
2046 | /* remember the number of threads in the array for later. */ |
2047 | group_size = i; | |
2f7ee569 TH |
2048 | tset.tc_array = group; |
2049 | tset.tc_array_len = group_size; | |
74a1166d | 2050 | |
134d3373 TH |
2051 | /* methods shouldn't be called if no task is actually migrating */ |
2052 | retval = 0; | |
892a2b90 | 2053 | if (!group_size) |
b07ef774 | 2054 | goto out_free_group_list; |
134d3373 | 2055 | |
74a1166d BB |
2056 | /* |
2057 | * step 1: check that we can legitimately attach to the cgroup. | |
2058 | */ | |
5549c497 | 2059 | for_each_root_subsys(root, ss) { |
eb95419b TH |
2060 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
2061 | ||
74a1166d | 2062 | if (ss->can_attach) { |
eb95419b | 2063 | retval = ss->can_attach(css, &tset); |
74a1166d BB |
2064 | if (retval) { |
2065 | failed_ss = ss; | |
2066 | goto out_cancel_attach; | |
2067 | } | |
2068 | } | |
74a1166d BB |
2069 | } |
2070 | ||
2071 | /* | |
2072 | * step 2: make sure css_sets exist for all threads to be migrated. | |
2073 | * we use find_css_set, which allocates a new one if necessary. | |
2074 | */ | |
74a1166d | 2075 | for (i = 0; i < group_size; i++) { |
a8ad805c TH |
2076 | struct css_set *old_cset; |
2077 | ||
134d3373 | 2078 | tc = flex_array_get(group, i); |
a8ad805c | 2079 | old_cset = task_css_set(tc->task); |
6f4b7e63 LZ |
2080 | tc->cset = find_css_set(old_cset, cgrp); |
2081 | if (!tc->cset) { | |
61d1d219 MSB |
2082 | retval = -ENOMEM; |
2083 | goto out_put_css_set_refs; | |
74a1166d BB |
2084 | } |
2085 | } | |
2086 | ||
2087 | /* | |
494c167c TH |
2088 | * step 3: now that we're guaranteed success wrt the css_sets, |
2089 | * proceed to move all tasks to the new cgroup. There are no | |
2090 | * failure cases after here, so this is the commit point. | |
74a1166d | 2091 | */ |
74a1166d | 2092 | for (i = 0; i < group_size; i++) { |
134d3373 | 2093 | tc = flex_array_get(group, i); |
6f4b7e63 | 2094 | cgroup_task_migrate(tc->cgrp, tc->task, tc->cset); |
74a1166d BB |
2095 | } |
2096 | /* nothing is sensitive to fork() after this point. */ | |
2097 | ||
2098 | /* | |
494c167c | 2099 | * step 4: do subsystem attach callbacks. |
74a1166d | 2100 | */ |
5549c497 | 2101 | for_each_root_subsys(root, ss) { |
eb95419b TH |
2102 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
2103 | ||
74a1166d | 2104 | if (ss->attach) |
eb95419b | 2105 | ss->attach(css, &tset); |
74a1166d BB |
2106 | } |
2107 | ||
2108 | /* | |
2109 | * step 5: success! and cleanup | |
2110 | */ | |
74a1166d | 2111 | retval = 0; |
61d1d219 MSB |
2112 | out_put_css_set_refs: |
2113 | if (retval) { | |
2114 | for (i = 0; i < group_size; i++) { | |
2115 | tc = flex_array_get(group, i); | |
6f4b7e63 | 2116 | if (!tc->cset) |
61d1d219 | 2117 | break; |
6f4b7e63 | 2118 | put_css_set(tc->cset); |
61d1d219 | 2119 | } |
74a1166d BB |
2120 | } |
2121 | out_cancel_attach: | |
74a1166d | 2122 | if (retval) { |
5549c497 | 2123 | for_each_root_subsys(root, ss) { |
eb95419b TH |
2124 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
2125 | ||
494c167c | 2126 | if (ss == failed_ss) |
74a1166d | 2127 | break; |
74a1166d | 2128 | if (ss->cancel_attach) |
eb95419b | 2129 | ss->cancel_attach(css, &tset); |
74a1166d BB |
2130 | } |
2131 | } | |
74a1166d | 2132 | out_free_group_list: |
d846687d | 2133 | flex_array_free(group); |
74a1166d BB |
2134 | return retval; |
2135 | } | |
2136 | ||
2137 | /* | |
2138 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 TH |
2139 | * function to attach either it or all tasks in its threadgroup. Will lock |
2140 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
bbcb81d0 | 2141 | */ |
74a1166d | 2142 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2143 | { |
bbcb81d0 | 2144 | struct task_struct *tsk; |
c69e8d9c | 2145 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2146 | int ret; |
2147 | ||
74a1166d BB |
2148 | if (!cgroup_lock_live_group(cgrp)) |
2149 | return -ENODEV; | |
2150 | ||
b78949eb MSB |
2151 | retry_find_task: |
2152 | rcu_read_lock(); | |
bbcb81d0 | 2153 | if (pid) { |
73507f33 | 2154 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2155 | if (!tsk) { |
2156 | rcu_read_unlock(); | |
b78949eb MSB |
2157 | ret= -ESRCH; |
2158 | goto out_unlock_cgroup; | |
bbcb81d0 | 2159 | } |
74a1166d BB |
2160 | /* |
2161 | * even if we're attaching all tasks in the thread group, we | |
2162 | * only need to check permissions on one of them. | |
2163 | */ | |
c69e8d9c | 2164 | tcred = __task_cred(tsk); |
14a590c3 EB |
2165 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
2166 | !uid_eq(cred->euid, tcred->uid) && | |
2167 | !uid_eq(cred->euid, tcred->suid)) { | |
c69e8d9c | 2168 | rcu_read_unlock(); |
b78949eb MSB |
2169 | ret = -EACCES; |
2170 | goto out_unlock_cgroup; | |
bbcb81d0 | 2171 | } |
b78949eb MSB |
2172 | } else |
2173 | tsk = current; | |
cd3d0952 TH |
2174 | |
2175 | if (threadgroup) | |
b78949eb | 2176 | tsk = tsk->group_leader; |
c4c27fbd MG |
2177 | |
2178 | /* | |
14a40ffc | 2179 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2180 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2181 | * with no rt_runtime allocated. Just say no. | |
2182 | */ | |
14a40ffc | 2183 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd MG |
2184 | ret = -EINVAL; |
2185 | rcu_read_unlock(); | |
2186 | goto out_unlock_cgroup; | |
2187 | } | |
2188 | ||
b78949eb MSB |
2189 | get_task_struct(tsk); |
2190 | rcu_read_unlock(); | |
2191 | ||
2192 | threadgroup_lock(tsk); | |
2193 | if (threadgroup) { | |
2194 | if (!thread_group_leader(tsk)) { | |
2195 | /* | |
2196 | * a race with de_thread from another thread's exec() | |
2197 | * may strip us of our leadership, if this happens, | |
2198 | * there is no choice but to throw this task away and | |
2199 | * try again; this is | |
2200 | * "double-double-toil-and-trouble-check locking". | |
2201 | */ | |
2202 | threadgroup_unlock(tsk); | |
2203 | put_task_struct(tsk); | |
2204 | goto retry_find_task; | |
2205 | } | |
081aa458 LZ |
2206 | } |
2207 | ||
2208 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
2209 | ||
cd3d0952 TH |
2210 | threadgroup_unlock(tsk); |
2211 | ||
bbcb81d0 | 2212 | put_task_struct(tsk); |
b78949eb | 2213 | out_unlock_cgroup: |
47cfcd09 | 2214 | mutex_unlock(&cgroup_mutex); |
bbcb81d0 PM |
2215 | return ret; |
2216 | } | |
2217 | ||
7ae1bad9 TH |
2218 | /** |
2219 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2220 | * @from: attach to all cgroups of a given task | |
2221 | * @tsk: the task to be attached | |
2222 | */ | |
2223 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2224 | { | |
2225 | struct cgroupfs_root *root; | |
2226 | int retval = 0; | |
2227 | ||
47cfcd09 | 2228 | mutex_lock(&cgroup_mutex); |
7ae1bad9 | 2229 | for_each_active_root(root) { |
6f4b7e63 | 2230 | struct cgroup *from_cgrp = task_cgroup_from_root(from, root); |
7ae1bad9 | 2231 | |
6f4b7e63 | 2232 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2233 | if (retval) |
2234 | break; | |
2235 | } | |
47cfcd09 | 2236 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2237 | |
2238 | return retval; | |
2239 | } | |
2240 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2241 | ||
182446d0 TH |
2242 | static int cgroup_tasks_write(struct cgroup_subsys_state *css, |
2243 | struct cftype *cft, u64 pid) | |
74a1166d | 2244 | { |
182446d0 | 2245 | return attach_task_by_pid(css->cgroup, pid, false); |
74a1166d BB |
2246 | } |
2247 | ||
182446d0 TH |
2248 | static int cgroup_procs_write(struct cgroup_subsys_state *css, |
2249 | struct cftype *cft, u64 tgid) | |
af351026 | 2250 | { |
182446d0 | 2251 | return attach_task_by_pid(css->cgroup, tgid, true); |
af351026 PM |
2252 | } |
2253 | ||
182446d0 TH |
2254 | static int cgroup_release_agent_write(struct cgroup_subsys_state *css, |
2255 | struct cftype *cft, const char *buffer) | |
e788e066 | 2256 | { |
182446d0 | 2257 | BUILD_BUG_ON(sizeof(css->cgroup->root->release_agent_path) < PATH_MAX); |
f4a2589f EK |
2258 | if (strlen(buffer) >= PATH_MAX) |
2259 | return -EINVAL; | |
182446d0 | 2260 | if (!cgroup_lock_live_group(css->cgroup)) |
e788e066 | 2261 | return -ENODEV; |
e25e2cbb | 2262 | mutex_lock(&cgroup_root_mutex); |
182446d0 | 2263 | strcpy(css->cgroup->root->release_agent_path, buffer); |
e25e2cbb | 2264 | mutex_unlock(&cgroup_root_mutex); |
47cfcd09 | 2265 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2266 | return 0; |
2267 | } | |
2268 | ||
182446d0 TH |
2269 | static int cgroup_release_agent_show(struct cgroup_subsys_state *css, |
2270 | struct cftype *cft, struct seq_file *seq) | |
e788e066 | 2271 | { |
182446d0 TH |
2272 | struct cgroup *cgrp = css->cgroup; |
2273 | ||
e788e066 PM |
2274 | if (!cgroup_lock_live_group(cgrp)) |
2275 | return -ENODEV; | |
2276 | seq_puts(seq, cgrp->root->release_agent_path); | |
2277 | seq_putc(seq, '\n'); | |
47cfcd09 | 2278 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2279 | return 0; |
2280 | } | |
2281 | ||
182446d0 TH |
2282 | static int cgroup_sane_behavior_show(struct cgroup_subsys_state *css, |
2283 | struct cftype *cft, struct seq_file *seq) | |
873fe09e | 2284 | { |
182446d0 | 2285 | seq_printf(seq, "%d\n", cgroup_sane_behavior(css->cgroup)); |
e788e066 PM |
2286 | return 0; |
2287 | } | |
2288 | ||
f7d58818 TH |
2289 | /* return the css for the given cgroup file */ |
2290 | static struct cgroup_subsys_state *cgroup_file_css(struct cfent *cfe) | |
2291 | { | |
2292 | struct cftype *cft = cfe->type; | |
2293 | struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent); | |
2294 | ||
2295 | if (cft->ss) | |
2296 | return cgrp->subsys[cft->ss->subsys_id]; | |
67f4c36f | 2297 | return &cgrp->dummy_css; |
f7d58818 TH |
2298 | } |
2299 | ||
84eea842 PM |
2300 | /* A buffer size big enough for numbers or short strings */ |
2301 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
2302 | ||
182446d0 TH |
2303 | static ssize_t cgroup_write_X64(struct cgroup_subsys_state *css, |
2304 | struct cftype *cft, struct file *file, | |
2305 | const char __user *userbuf, size_t nbytes, | |
2306 | loff_t *unused_ppos) | |
355e0c48 | 2307 | { |
84eea842 | 2308 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 2309 | int retval = 0; |
355e0c48 PM |
2310 | char *end; |
2311 | ||
2312 | if (!nbytes) | |
2313 | return -EINVAL; | |
2314 | if (nbytes >= sizeof(buffer)) | |
2315 | return -E2BIG; | |
2316 | if (copy_from_user(buffer, userbuf, nbytes)) | |
2317 | return -EFAULT; | |
2318 | ||
2319 | buffer[nbytes] = 0; /* nul-terminate */ | |
e73d2c61 | 2320 | if (cft->write_u64) { |
478988d3 | 2321 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2322 | if (*end) |
2323 | return -EINVAL; | |
182446d0 | 2324 | retval = cft->write_u64(css, cft, val); |
e73d2c61 | 2325 | } else { |
478988d3 | 2326 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2327 | if (*end) |
2328 | return -EINVAL; | |
182446d0 | 2329 | retval = cft->write_s64(css, cft, val); |
e73d2c61 | 2330 | } |
355e0c48 PM |
2331 | if (!retval) |
2332 | retval = nbytes; | |
2333 | return retval; | |
2334 | } | |
2335 | ||
182446d0 TH |
2336 | static ssize_t cgroup_write_string(struct cgroup_subsys_state *css, |
2337 | struct cftype *cft, struct file *file, | |
2338 | const char __user *userbuf, size_t nbytes, | |
2339 | loff_t *unused_ppos) | |
db3b1497 | 2340 | { |
84eea842 | 2341 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
2342 | int retval = 0; |
2343 | size_t max_bytes = cft->max_write_len; | |
2344 | char *buffer = local_buffer; | |
2345 | ||
2346 | if (!max_bytes) | |
2347 | max_bytes = sizeof(local_buffer) - 1; | |
2348 | if (nbytes >= max_bytes) | |
2349 | return -E2BIG; | |
2350 | /* Allocate a dynamic buffer if we need one */ | |
2351 | if (nbytes >= sizeof(local_buffer)) { | |
2352 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2353 | if (buffer == NULL) | |
2354 | return -ENOMEM; | |
2355 | } | |
5a3eb9f6 LZ |
2356 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2357 | retval = -EFAULT; | |
2358 | goto out; | |
2359 | } | |
db3b1497 PM |
2360 | |
2361 | buffer[nbytes] = 0; /* nul-terminate */ | |
182446d0 | 2362 | retval = cft->write_string(css, cft, strstrip(buffer)); |
db3b1497 PM |
2363 | if (!retval) |
2364 | retval = nbytes; | |
5a3eb9f6 | 2365 | out: |
db3b1497 PM |
2366 | if (buffer != local_buffer) |
2367 | kfree(buffer); | |
2368 | return retval; | |
2369 | } | |
2370 | ||
ddbcc7e8 | 2371 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
182446d0 | 2372 | size_t nbytes, loff_t *ppos) |
ddbcc7e8 | 2373 | { |
182446d0 | 2374 | struct cfent *cfe = __d_cfe(file->f_dentry); |
ddbcc7e8 | 2375 | struct cftype *cft = __d_cft(file->f_dentry); |
182446d0 | 2376 | struct cgroup_subsys_state *css = cgroup_file_css(cfe); |
ddbcc7e8 | 2377 | |
355e0c48 | 2378 | if (cft->write) |
182446d0 | 2379 | return cft->write(css, cft, file, buf, nbytes, ppos); |
e73d2c61 | 2380 | if (cft->write_u64 || cft->write_s64) |
182446d0 | 2381 | return cgroup_write_X64(css, cft, file, buf, nbytes, ppos); |
db3b1497 | 2382 | if (cft->write_string) |
182446d0 | 2383 | return cgroup_write_string(css, cft, file, buf, nbytes, ppos); |
d447ea2f | 2384 | if (cft->trigger) { |
182446d0 | 2385 | int ret = cft->trigger(css, (unsigned int)cft->private); |
d447ea2f PE |
2386 | return ret ? ret : nbytes; |
2387 | } | |
355e0c48 | 2388 | return -EINVAL; |
ddbcc7e8 PM |
2389 | } |
2390 | ||
182446d0 TH |
2391 | static ssize_t cgroup_read_u64(struct cgroup_subsys_state *css, |
2392 | struct cftype *cft, struct file *file, | |
2393 | char __user *buf, size_t nbytes, loff_t *ppos) | |
ddbcc7e8 | 2394 | { |
84eea842 | 2395 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
182446d0 | 2396 | u64 val = cft->read_u64(css, cft); |
ddbcc7e8 PM |
2397 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2398 | ||
2399 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2400 | } | |
2401 | ||
182446d0 TH |
2402 | static ssize_t cgroup_read_s64(struct cgroup_subsys_state *css, |
2403 | struct cftype *cft, struct file *file, | |
2404 | char __user *buf, size_t nbytes, loff_t *ppos) | |
e73d2c61 | 2405 | { |
84eea842 | 2406 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
182446d0 | 2407 | s64 val = cft->read_s64(css, cft); |
e73d2c61 PM |
2408 | int len = sprintf(tmp, "%lld\n", (long long) val); |
2409 | ||
2410 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2411 | } | |
2412 | ||
ddbcc7e8 | 2413 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
182446d0 | 2414 | size_t nbytes, loff_t *ppos) |
ddbcc7e8 | 2415 | { |
182446d0 | 2416 | struct cfent *cfe = __d_cfe(file->f_dentry); |
ddbcc7e8 | 2417 | struct cftype *cft = __d_cft(file->f_dentry); |
182446d0 | 2418 | struct cgroup_subsys_state *css = cgroup_file_css(cfe); |
ddbcc7e8 | 2419 | |
ddbcc7e8 | 2420 | if (cft->read) |
182446d0 | 2421 | return cft->read(css, cft, file, buf, nbytes, ppos); |
f4c753b7 | 2422 | if (cft->read_u64) |
182446d0 | 2423 | return cgroup_read_u64(css, cft, file, buf, nbytes, ppos); |
e73d2c61 | 2424 | if (cft->read_s64) |
182446d0 | 2425 | return cgroup_read_s64(css, cft, file, buf, nbytes, ppos); |
ddbcc7e8 PM |
2426 | return -EINVAL; |
2427 | } | |
2428 | ||
91796569 PM |
2429 | /* |
2430 | * seqfile ops/methods for returning structured data. Currently just | |
2431 | * supports string->u64 maps, but can be extended in future. | |
2432 | */ | |
2433 | ||
91796569 PM |
2434 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) |
2435 | { | |
2436 | struct seq_file *sf = cb->state; | |
2437 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2438 | } | |
2439 | ||
2440 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2441 | { | |
e0798ce2 LZ |
2442 | struct cfent *cfe = m->private; |
2443 | struct cftype *cft = cfe->type; | |
182446d0 | 2444 | struct cgroup_subsys_state *css = cgroup_file_css(cfe); |
e0798ce2 | 2445 | |
29486df3 SH |
2446 | if (cft->read_map) { |
2447 | struct cgroup_map_cb cb = { | |
2448 | .fill = cgroup_map_add, | |
2449 | .state = m, | |
2450 | }; | |
182446d0 | 2451 | return cft->read_map(css, cft, &cb); |
29486df3 | 2452 | } |
182446d0 | 2453 | return cft->read_seq_string(css, cft, m); |
91796569 PM |
2454 | } |
2455 | ||
828c0950 | 2456 | static const struct file_operations cgroup_seqfile_operations = { |
91796569 | 2457 | .read = seq_read, |
e788e066 | 2458 | .write = cgroup_file_write, |
91796569 | 2459 | .llseek = seq_lseek, |
e0798ce2 | 2460 | .release = single_release, |
91796569 PM |
2461 | }; |
2462 | ||
ddbcc7e8 PM |
2463 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2464 | { | |
f7d58818 TH |
2465 | struct cfent *cfe = __d_cfe(file->f_dentry); |
2466 | struct cftype *cft = __d_cft(file->f_dentry); | |
2467 | struct cgroup_subsys_state *css = cgroup_file_css(cfe); | |
ddbcc7e8 | 2468 | int err; |
ddbcc7e8 PM |
2469 | |
2470 | err = generic_file_open(inode, file); | |
2471 | if (err) | |
2472 | return err; | |
f7d58818 TH |
2473 | |
2474 | /* | |
2475 | * If the file belongs to a subsystem, pin the css. Will be | |
2476 | * unpinned either on open failure or release. This ensures that | |
2477 | * @css stays alive for all file operations. | |
2478 | */ | |
67f4c36f | 2479 | if (css->ss && !css_tryget(css)) |
f7d58818 | 2480 | return -ENODEV; |
75139b82 | 2481 | |
29486df3 | 2482 | if (cft->read_map || cft->read_seq_string) { |
91796569 | 2483 | file->f_op = &cgroup_seqfile_operations; |
e0798ce2 LZ |
2484 | err = single_open(file, cgroup_seqfile_show, cfe); |
2485 | } else if (cft->open) { | |
ddbcc7e8 | 2486 | err = cft->open(inode, file); |
e0798ce2 | 2487 | } |
ddbcc7e8 | 2488 | |
67f4c36f | 2489 | if (css->ss && err) |
f7d58818 | 2490 | css_put(css); |
ddbcc7e8 PM |
2491 | return err; |
2492 | } | |
2493 | ||
2494 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2495 | { | |
f7d58818 | 2496 | struct cfent *cfe = __d_cfe(file->f_dentry); |
ddbcc7e8 | 2497 | struct cftype *cft = __d_cft(file->f_dentry); |
f7d58818 TH |
2498 | struct cgroup_subsys_state *css = cgroup_file_css(cfe); |
2499 | int ret = 0; | |
2500 | ||
ddbcc7e8 | 2501 | if (cft->release) |
f7d58818 | 2502 | ret = cft->release(inode, file); |
67f4c36f | 2503 | if (css->ss) |
f7d58818 TH |
2504 | css_put(css); |
2505 | return ret; | |
ddbcc7e8 PM |
2506 | } |
2507 | ||
2508 | /* | |
2509 | * cgroup_rename - Only allow simple rename of directories in place. | |
2510 | */ | |
2511 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2512 | struct inode *new_dir, struct dentry *new_dentry) | |
2513 | { | |
65dff759 LZ |
2514 | int ret; |
2515 | struct cgroup_name *name, *old_name; | |
2516 | struct cgroup *cgrp; | |
2517 | ||
2518 | /* | |
2519 | * It's convinient to use parent dir's i_mutex to protected | |
2520 | * cgrp->name. | |
2521 | */ | |
2522 | lockdep_assert_held(&old_dir->i_mutex); | |
2523 | ||
ddbcc7e8 PM |
2524 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) |
2525 | return -ENOTDIR; | |
2526 | if (new_dentry->d_inode) | |
2527 | return -EEXIST; | |
2528 | if (old_dir != new_dir) | |
2529 | return -EIO; | |
65dff759 LZ |
2530 | |
2531 | cgrp = __d_cgrp(old_dentry); | |
2532 | ||
6db8e85c TH |
2533 | /* |
2534 | * This isn't a proper migration and its usefulness is very | |
2535 | * limited. Disallow if sane_behavior. | |
2536 | */ | |
2537 | if (cgroup_sane_behavior(cgrp)) | |
2538 | return -EPERM; | |
2539 | ||
65dff759 LZ |
2540 | name = cgroup_alloc_name(new_dentry); |
2541 | if (!name) | |
2542 | return -ENOMEM; | |
2543 | ||
2544 | ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2545 | if (ret) { | |
2546 | kfree(name); | |
2547 | return ret; | |
2548 | } | |
2549 | ||
a4ea1cc9 | 2550 | old_name = rcu_dereference_protected(cgrp->name, true); |
65dff759 LZ |
2551 | rcu_assign_pointer(cgrp->name, name); |
2552 | ||
2553 | kfree_rcu(old_name, rcu_head); | |
2554 | return 0; | |
ddbcc7e8 PM |
2555 | } |
2556 | ||
03b1cde6 AR |
2557 | static struct simple_xattrs *__d_xattrs(struct dentry *dentry) |
2558 | { | |
2559 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
2560 | return &__d_cgrp(dentry)->xattrs; | |
2561 | else | |
712317ad | 2562 | return &__d_cfe(dentry)->xattrs; |
03b1cde6 AR |
2563 | } |
2564 | ||
2565 | static inline int xattr_enabled(struct dentry *dentry) | |
2566 | { | |
2567 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; | |
93438629 | 2568 | return root->flags & CGRP_ROOT_XATTR; |
03b1cde6 AR |
2569 | } |
2570 | ||
2571 | static bool is_valid_xattr(const char *name) | |
2572 | { | |
2573 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || | |
2574 | !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) | |
2575 | return true; | |
2576 | return false; | |
2577 | } | |
2578 | ||
2579 | static int cgroup_setxattr(struct dentry *dentry, const char *name, | |
2580 | const void *val, size_t size, int flags) | |
2581 | { | |
2582 | if (!xattr_enabled(dentry)) | |
2583 | return -EOPNOTSUPP; | |
2584 | if (!is_valid_xattr(name)) | |
2585 | return -EINVAL; | |
2586 | return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); | |
2587 | } | |
2588 | ||
2589 | static int cgroup_removexattr(struct dentry *dentry, const char *name) | |
2590 | { | |
2591 | if (!xattr_enabled(dentry)) | |
2592 | return -EOPNOTSUPP; | |
2593 | if (!is_valid_xattr(name)) | |
2594 | return -EINVAL; | |
2595 | return simple_xattr_remove(__d_xattrs(dentry), name); | |
2596 | } | |
2597 | ||
2598 | static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, | |
2599 | void *buf, size_t size) | |
2600 | { | |
2601 | if (!xattr_enabled(dentry)) | |
2602 | return -EOPNOTSUPP; | |
2603 | if (!is_valid_xattr(name)) | |
2604 | return -EINVAL; | |
2605 | return simple_xattr_get(__d_xattrs(dentry), name, buf, size); | |
2606 | } | |
2607 | ||
2608 | static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) | |
2609 | { | |
2610 | if (!xattr_enabled(dentry)) | |
2611 | return -EOPNOTSUPP; | |
2612 | return simple_xattr_list(__d_xattrs(dentry), buf, size); | |
2613 | } | |
2614 | ||
828c0950 | 2615 | static const struct file_operations cgroup_file_operations = { |
ddbcc7e8 PM |
2616 | .read = cgroup_file_read, |
2617 | .write = cgroup_file_write, | |
2618 | .llseek = generic_file_llseek, | |
2619 | .open = cgroup_file_open, | |
2620 | .release = cgroup_file_release, | |
2621 | }; | |
2622 | ||
03b1cde6 AR |
2623 | static const struct inode_operations cgroup_file_inode_operations = { |
2624 | .setxattr = cgroup_setxattr, | |
2625 | .getxattr = cgroup_getxattr, | |
2626 | .listxattr = cgroup_listxattr, | |
2627 | .removexattr = cgroup_removexattr, | |
2628 | }; | |
2629 | ||
6e1d5dcc | 2630 | static const struct inode_operations cgroup_dir_inode_operations = { |
c72a04e3 | 2631 | .lookup = cgroup_lookup, |
ddbcc7e8 PM |
2632 | .mkdir = cgroup_mkdir, |
2633 | .rmdir = cgroup_rmdir, | |
2634 | .rename = cgroup_rename, | |
03b1cde6 AR |
2635 | .setxattr = cgroup_setxattr, |
2636 | .getxattr = cgroup_getxattr, | |
2637 | .listxattr = cgroup_listxattr, | |
2638 | .removexattr = cgroup_removexattr, | |
ddbcc7e8 PM |
2639 | }; |
2640 | ||
00cd8dd3 | 2641 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
c72a04e3 AV |
2642 | { |
2643 | if (dentry->d_name.len > NAME_MAX) | |
2644 | return ERR_PTR(-ENAMETOOLONG); | |
2645 | d_add(dentry, NULL); | |
2646 | return NULL; | |
2647 | } | |
2648 | ||
0dea1168 KS |
2649 | /* |
2650 | * Check if a file is a control file | |
2651 | */ | |
2652 | static inline struct cftype *__file_cft(struct file *file) | |
2653 | { | |
496ad9aa | 2654 | if (file_inode(file)->i_fop != &cgroup_file_operations) |
0dea1168 KS |
2655 | return ERR_PTR(-EINVAL); |
2656 | return __d_cft(file->f_dentry); | |
2657 | } | |
2658 | ||
a5e7ed32 | 2659 | static int cgroup_create_file(struct dentry *dentry, umode_t mode, |
5adcee1d NP |
2660 | struct super_block *sb) |
2661 | { | |
ddbcc7e8 PM |
2662 | struct inode *inode; |
2663 | ||
2664 | if (!dentry) | |
2665 | return -ENOENT; | |
2666 | if (dentry->d_inode) | |
2667 | return -EEXIST; | |
2668 | ||
2669 | inode = cgroup_new_inode(mode, sb); | |
2670 | if (!inode) | |
2671 | return -ENOMEM; | |
2672 | ||
2673 | if (S_ISDIR(mode)) { | |
2674 | inode->i_op = &cgroup_dir_inode_operations; | |
2675 | inode->i_fop = &simple_dir_operations; | |
2676 | ||
2677 | /* start off with i_nlink == 2 (for "." entry) */ | |
2678 | inc_nlink(inode); | |
28fd6f30 | 2679 | inc_nlink(dentry->d_parent->d_inode); |
ddbcc7e8 | 2680 | |
b8a2df6a TH |
2681 | /* |
2682 | * Control reaches here with cgroup_mutex held. | |
2683 | * @inode->i_mutex should nest outside cgroup_mutex but we | |
2684 | * want to populate it immediately without releasing | |
2685 | * cgroup_mutex. As @inode isn't visible to anyone else | |
2686 | * yet, trylock will always succeed without affecting | |
2687 | * lockdep checks. | |
2688 | */ | |
2689 | WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex)); | |
ddbcc7e8 PM |
2690 | } else if (S_ISREG(mode)) { |
2691 | inode->i_size = 0; | |
2692 | inode->i_fop = &cgroup_file_operations; | |
03b1cde6 | 2693 | inode->i_op = &cgroup_file_inode_operations; |
ddbcc7e8 | 2694 | } |
ddbcc7e8 PM |
2695 | d_instantiate(dentry, inode); |
2696 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2697 | return 0; | |
2698 | } | |
2699 | ||
099fca32 LZ |
2700 | /** |
2701 | * cgroup_file_mode - deduce file mode of a control file | |
2702 | * @cft: the control file in question | |
2703 | * | |
2704 | * returns cft->mode if ->mode is not 0 | |
2705 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2706 | * returns S_IRUGO if it has only a read handler | |
2707 | * returns S_IWUSR if it has only a write hander | |
2708 | */ | |
a5e7ed32 | 2709 | static umode_t cgroup_file_mode(const struct cftype *cft) |
099fca32 | 2710 | { |
a5e7ed32 | 2711 | umode_t mode = 0; |
099fca32 LZ |
2712 | |
2713 | if (cft->mode) | |
2714 | return cft->mode; | |
2715 | ||
2716 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2717 | cft->read_map || cft->read_seq_string) | |
2718 | mode |= S_IRUGO; | |
2719 | ||
2720 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2721 | cft->write_string || cft->trigger) | |
2722 | mode |= S_IWUSR; | |
2723 | ||
2724 | return mode; | |
2725 | } | |
2726 | ||
2bb566cb | 2727 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) |
ddbcc7e8 | 2728 | { |
bd89aabc | 2729 | struct dentry *dir = cgrp->dentry; |
05ef1d7c | 2730 | struct cgroup *parent = __d_cgrp(dir); |
ddbcc7e8 | 2731 | struct dentry *dentry; |
05ef1d7c | 2732 | struct cfent *cfe; |
ddbcc7e8 | 2733 | int error; |
a5e7ed32 | 2734 | umode_t mode; |
ddbcc7e8 | 2735 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
8e3f6541 | 2736 | |
2bb566cb TH |
2737 | if (cft->ss && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { |
2738 | strcpy(name, cft->ss->name); | |
ddbcc7e8 PM |
2739 | strcat(name, "."); |
2740 | } | |
2741 | strcat(name, cft->name); | |
05ef1d7c | 2742 | |
ddbcc7e8 | 2743 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); |
05ef1d7c TH |
2744 | |
2745 | cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); | |
2746 | if (!cfe) | |
2747 | return -ENOMEM; | |
2748 | ||
ddbcc7e8 | 2749 | dentry = lookup_one_len(name, dir, strlen(name)); |
05ef1d7c | 2750 | if (IS_ERR(dentry)) { |
ddbcc7e8 | 2751 | error = PTR_ERR(dentry); |
05ef1d7c TH |
2752 | goto out; |
2753 | } | |
2754 | ||
d6cbf35d LZ |
2755 | cfe->type = (void *)cft; |
2756 | cfe->dentry = dentry; | |
2757 | dentry->d_fsdata = cfe; | |
2758 | simple_xattrs_init(&cfe->xattrs); | |
2759 | ||
05ef1d7c TH |
2760 | mode = cgroup_file_mode(cft); |
2761 | error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); | |
2762 | if (!error) { | |
05ef1d7c TH |
2763 | list_add_tail(&cfe->node, &parent->files); |
2764 | cfe = NULL; | |
2765 | } | |
2766 | dput(dentry); | |
2767 | out: | |
2768 | kfree(cfe); | |
ddbcc7e8 PM |
2769 | return error; |
2770 | } | |
2771 | ||
b1f28d31 TH |
2772 | /** |
2773 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
2774 | * @cgrp: the target cgroup | |
b1f28d31 TH |
2775 | * @cfts: array of cftypes to be added |
2776 | * @is_add: whether to add or remove | |
2777 | * | |
2778 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
2bb566cb TH |
2779 | * For removals, this function never fails. If addition fails, this |
2780 | * function doesn't remove files already added. The caller is responsible | |
2781 | * for cleaning up. | |
b1f28d31 | 2782 | */ |
2bb566cb TH |
2783 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
2784 | bool is_add) | |
ddbcc7e8 | 2785 | { |
03b1cde6 | 2786 | struct cftype *cft; |
b1f28d31 TH |
2787 | int ret; |
2788 | ||
2789 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); | |
2790 | lockdep_assert_held(&cgroup_mutex); | |
db0416b6 TH |
2791 | |
2792 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 2793 | /* does cft->flags tell us to skip this file on @cgrp? */ |
873fe09e TH |
2794 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) |
2795 | continue; | |
f33fddc2 G |
2796 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
2797 | continue; | |
2798 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2799 | continue; | |
2800 | ||
2739d3cc | 2801 | if (is_add) { |
2bb566cb | 2802 | ret = cgroup_add_file(cgrp, cft); |
b1f28d31 | 2803 | if (ret) { |
2739d3cc | 2804 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", |
b1f28d31 TH |
2805 | cft->name, ret); |
2806 | return ret; | |
2807 | } | |
2739d3cc LZ |
2808 | } else { |
2809 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2810 | } |
ddbcc7e8 | 2811 | } |
b1f28d31 | 2812 | return 0; |
ddbcc7e8 PM |
2813 | } |
2814 | ||
8e3f6541 | 2815 | static void cgroup_cfts_prepare(void) |
e8c82d20 | 2816 | __acquires(&cgroup_mutex) |
8e3f6541 TH |
2817 | { |
2818 | /* | |
2819 | * Thanks to the entanglement with vfs inode locking, we can't walk | |
2820 | * the existing cgroups under cgroup_mutex and create files. | |
492eb21b TH |
2821 | * Instead, we use css_for_each_descendant_pre() and drop RCU read |
2822 | * lock before calling cgroup_addrm_files(). | |
8e3f6541 | 2823 | */ |
8e3f6541 TH |
2824 | mutex_lock(&cgroup_mutex); |
2825 | } | |
2826 | ||
2bb566cb | 2827 | static int cgroup_cfts_commit(struct cftype *cfts, bool is_add) |
e8c82d20 | 2828 | __releases(&cgroup_mutex) |
8e3f6541 TH |
2829 | { |
2830 | LIST_HEAD(pending); | |
2bb566cb | 2831 | struct cgroup_subsys *ss = cfts[0].ss; |
492eb21b | 2832 | struct cgroup *root = &ss->root->top_cgroup; |
084457f2 | 2833 | struct super_block *sb = ss->root->sb; |
e8c82d20 LZ |
2834 | struct dentry *prev = NULL; |
2835 | struct inode *inode; | |
492eb21b | 2836 | struct cgroup_subsys_state *css; |
00356bd5 | 2837 | u64 update_before; |
9ccece80 | 2838 | int ret = 0; |
8e3f6541 TH |
2839 | |
2840 | /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ | |
9871bf95 | 2841 | if (!cfts || ss->root == &cgroup_dummy_root || |
e8c82d20 LZ |
2842 | !atomic_inc_not_zero(&sb->s_active)) { |
2843 | mutex_unlock(&cgroup_mutex); | |
9ccece80 | 2844 | return 0; |
8e3f6541 TH |
2845 | } |
2846 | ||
8e3f6541 | 2847 | /* |
e8c82d20 LZ |
2848 | * All cgroups which are created after we drop cgroup_mutex will |
2849 | * have the updated set of files, so we only need to update the | |
00356bd5 | 2850 | * cgroups created before the current @cgroup_serial_nr_next. |
8e3f6541 | 2851 | */ |
00356bd5 | 2852 | update_before = cgroup_serial_nr_next; |
e8c82d20 LZ |
2853 | |
2854 | mutex_unlock(&cgroup_mutex); | |
2855 | ||
2856 | /* @root always needs to be updated */ | |
2857 | inode = root->dentry->d_inode; | |
2858 | mutex_lock(&inode->i_mutex); | |
2859 | mutex_lock(&cgroup_mutex); | |
2bb566cb | 2860 | ret = cgroup_addrm_files(root, cfts, is_add); |
e8c82d20 LZ |
2861 | mutex_unlock(&cgroup_mutex); |
2862 | mutex_unlock(&inode->i_mutex); | |
2863 | ||
9ccece80 TH |
2864 | if (ret) |
2865 | goto out_deact; | |
2866 | ||
e8c82d20 LZ |
2867 | /* add/rm files for all cgroups created before */ |
2868 | rcu_read_lock(); | |
492eb21b TH |
2869 | css_for_each_descendant_pre(css, cgroup_css(root, ss->subsys_id)) { |
2870 | struct cgroup *cgrp = css->cgroup; | |
2871 | ||
e8c82d20 LZ |
2872 | if (cgroup_is_dead(cgrp)) |
2873 | continue; | |
2874 | ||
2875 | inode = cgrp->dentry->d_inode; | |
2876 | dget(cgrp->dentry); | |
2877 | rcu_read_unlock(); | |
2878 | ||
2879 | dput(prev); | |
2880 | prev = cgrp->dentry; | |
8e3f6541 TH |
2881 | |
2882 | mutex_lock(&inode->i_mutex); | |
2883 | mutex_lock(&cgroup_mutex); | |
00356bd5 | 2884 | if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp)) |
2bb566cb | 2885 | ret = cgroup_addrm_files(cgrp, cfts, is_add); |
8e3f6541 TH |
2886 | mutex_unlock(&cgroup_mutex); |
2887 | mutex_unlock(&inode->i_mutex); | |
2888 | ||
e8c82d20 | 2889 | rcu_read_lock(); |
9ccece80 TH |
2890 | if (ret) |
2891 | break; | |
8e3f6541 | 2892 | } |
e8c82d20 LZ |
2893 | rcu_read_unlock(); |
2894 | dput(prev); | |
9ccece80 | 2895 | out_deact: |
e8c82d20 | 2896 | deactivate_super(sb); |
9ccece80 | 2897 | return ret; |
8e3f6541 TH |
2898 | } |
2899 | ||
2900 | /** | |
2901 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2902 | * @ss: target cgroup subsystem | |
2903 | * @cfts: zero-length name terminated array of cftypes | |
2904 | * | |
2905 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2906 | * existing cgroups to which @ss is attached and all future cgroups will | |
2907 | * have them too. This function can be called anytime whether @ss is | |
2908 | * attached or not. | |
2909 | * | |
2910 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2911 | * function currently returns 0 as long as @cfts registration is successful | |
2912 | * even if some file creation attempts on existing cgroups fail. | |
2913 | */ | |
03b1cde6 | 2914 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 TH |
2915 | { |
2916 | struct cftype_set *set; | |
2bb566cb | 2917 | struct cftype *cft; |
9ccece80 | 2918 | int ret; |
8e3f6541 TH |
2919 | |
2920 | set = kzalloc(sizeof(*set), GFP_KERNEL); | |
2921 | if (!set) | |
2922 | return -ENOMEM; | |
2923 | ||
2bb566cb TH |
2924 | for (cft = cfts; cft->name[0] != '\0'; cft++) |
2925 | cft->ss = ss; | |
2926 | ||
8e3f6541 TH |
2927 | cgroup_cfts_prepare(); |
2928 | set->cfts = cfts; | |
2929 | list_add_tail(&set->node, &ss->cftsets); | |
2bb566cb | 2930 | ret = cgroup_cfts_commit(cfts, true); |
9ccece80 | 2931 | if (ret) |
2bb566cb | 2932 | cgroup_rm_cftypes(cfts); |
9ccece80 | 2933 | return ret; |
8e3f6541 TH |
2934 | } |
2935 | EXPORT_SYMBOL_GPL(cgroup_add_cftypes); | |
2936 | ||
79578621 TH |
2937 | /** |
2938 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
2939 | * @cfts: zero-length name terminated array of cftypes |
2940 | * | |
2bb566cb TH |
2941 | * Unregister @cfts. Files described by @cfts are removed from all |
2942 | * existing cgroups and all future cgroups won't have them either. This | |
2943 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
2944 | * |
2945 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 2946 | * registered. |
79578621 | 2947 | */ |
2bb566cb | 2948 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 TH |
2949 | { |
2950 | struct cftype_set *set; | |
2951 | ||
2bb566cb TH |
2952 | if (!cfts || !cfts[0].ss) |
2953 | return -ENOENT; | |
2954 | ||
79578621 TH |
2955 | cgroup_cfts_prepare(); |
2956 | ||
2bb566cb | 2957 | list_for_each_entry(set, &cfts[0].ss->cftsets, node) { |
79578621 | 2958 | if (set->cfts == cfts) { |
f57947d2 LZ |
2959 | list_del(&set->node); |
2960 | kfree(set); | |
2bb566cb | 2961 | cgroup_cfts_commit(cfts, false); |
79578621 TH |
2962 | return 0; |
2963 | } | |
2964 | } | |
2965 | ||
2bb566cb | 2966 | cgroup_cfts_commit(NULL, false); |
79578621 TH |
2967 | return -ENOENT; |
2968 | } | |
2969 | ||
a043e3b2 LZ |
2970 | /** |
2971 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2972 | * @cgrp: the cgroup in question | |
2973 | * | |
2974 | * Return the number of tasks in the cgroup. | |
2975 | */ | |
bd89aabc | 2976 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2977 | { |
2978 | int count = 0; | |
69d0206c | 2979 | struct cgrp_cset_link *link; |
817929ec PM |
2980 | |
2981 | read_lock(&css_set_lock); | |
69d0206c TH |
2982 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
2983 | count += atomic_read(&link->cset->refcount); | |
817929ec | 2984 | read_unlock(&css_set_lock); |
bbcb81d0 PM |
2985 | return count; |
2986 | } | |
2987 | ||
31a7df01 | 2988 | /* |
0942eeee TH |
2989 | * To reduce the fork() overhead for systems that are not actually using |
2990 | * their cgroups capability, we don't maintain the lists running through | |
2991 | * each css_set to its tasks until we see the list actually used - in other | |
2992 | * words after the first call to cgroup_task_iter_start(). | |
31a7df01 | 2993 | */ |
3df91fe3 | 2994 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
2995 | { |
2996 | struct task_struct *p, *g; | |
2997 | write_lock(&css_set_lock); | |
2998 | use_task_css_set_links = 1; | |
3ce3230a FW |
2999 | /* |
3000 | * We need tasklist_lock because RCU is not safe against | |
3001 | * while_each_thread(). Besides, a forking task that has passed | |
3002 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
3003 | * is not guaranteed to have its child immediately visible in the | |
3004 | * tasklist if we walk through it with RCU. | |
3005 | */ | |
3006 | read_lock(&tasklist_lock); | |
31a7df01 CW |
3007 | do_each_thread(g, p) { |
3008 | task_lock(p); | |
0e04388f LZ |
3009 | /* |
3010 | * We should check if the process is exiting, otherwise | |
3011 | * it will race with cgroup_exit() in that the list | |
3012 | * entry won't be deleted though the process has exited. | |
3013 | */ | |
3014 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
a8ad805c | 3015 | list_add(&p->cg_list, &task_css_set(p)->tasks); |
31a7df01 CW |
3016 | task_unlock(p); |
3017 | } while_each_thread(g, p); | |
3ce3230a | 3018 | read_unlock(&tasklist_lock); |
31a7df01 CW |
3019 | write_unlock(&css_set_lock); |
3020 | } | |
3021 | ||
53fa5261 | 3022 | /** |
492eb21b TH |
3023 | * css_next_child - find the next child of a given css |
3024 | * @pos_css: the current position (%NULL to initiate traversal) | |
3025 | * @parent_css: css whose children to walk | |
53fa5261 | 3026 | * |
492eb21b TH |
3027 | * This function returns the next child of @parent_css and should be called |
3028 | * under RCU read lock. The only requirement is that @parent_css and | |
3029 | * @pos_css are accessible. The next sibling is guaranteed to be returned | |
3030 | * regardless of their states. | |
53fa5261 | 3031 | */ |
492eb21b TH |
3032 | struct cgroup_subsys_state * |
3033 | css_next_child(struct cgroup_subsys_state *pos_css, | |
3034 | struct cgroup_subsys_state *parent_css) | |
53fa5261 | 3035 | { |
492eb21b TH |
3036 | struct cgroup *pos = pos_css ? pos_css->cgroup : NULL; |
3037 | struct cgroup *cgrp = parent_css->cgroup; | |
53fa5261 TH |
3038 | struct cgroup *next; |
3039 | ||
3040 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3041 | ||
3042 | /* | |
3043 | * @pos could already have been removed. Once a cgroup is removed, | |
3044 | * its ->sibling.next is no longer updated when its next sibling | |
ea15f8cc TH |
3045 | * changes. As CGRP_DEAD assertion is serialized and happens |
3046 | * before the cgroup is taken off the ->sibling list, if we see it | |
3047 | * unasserted, it's guaranteed that the next sibling hasn't | |
3048 | * finished its grace period even if it's already removed, and thus | |
3049 | * safe to dereference from this RCU critical section. If | |
3050 | * ->sibling.next is inaccessible, cgroup_is_dead() is guaranteed | |
3051 | * to be visible as %true here. | |
3b287a50 TH |
3052 | * |
3053 | * If @pos is dead, its next pointer can't be dereferenced; | |
3054 | * however, as each cgroup is given a monotonically increasing | |
3055 | * unique serial number and always appended to the sibling list, | |
3056 | * the next one can be found by walking the parent's children until | |
3057 | * we see a cgroup with higher serial number than @pos's. While | |
3058 | * this path can be slower, it's taken only when either the current | |
3059 | * cgroup is removed or iteration and removal race. | |
53fa5261 | 3060 | */ |
3b287a50 TH |
3061 | if (!pos) { |
3062 | next = list_entry_rcu(cgrp->children.next, struct cgroup, sibling); | |
3063 | } else if (likely(!cgroup_is_dead(pos))) { | |
53fa5261 | 3064 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); |
3b287a50 TH |
3065 | } else { |
3066 | list_for_each_entry_rcu(next, &cgrp->children, sibling) | |
3067 | if (next->serial_nr > pos->serial_nr) | |
3068 | break; | |
53fa5261 TH |
3069 | } |
3070 | ||
492eb21b TH |
3071 | if (&next->sibling == &cgrp->children) |
3072 | return NULL; | |
3073 | ||
3074 | if (parent_css->ss) | |
3075 | return cgroup_css(next, parent_css->ss->subsys_id); | |
3076 | else | |
3077 | return &next->dummy_css; | |
53fa5261 | 3078 | } |
492eb21b | 3079 | EXPORT_SYMBOL_GPL(css_next_child); |
53fa5261 | 3080 | |
574bd9f7 | 3081 | /** |
492eb21b | 3082 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 3083 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3084 | * @root: css whose descendants to walk |
574bd9f7 | 3085 | * |
492eb21b TH |
3086 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
3087 | * to visit for pre-order traversal of @root's descendants. | |
75501a6d TH |
3088 | * |
3089 | * While this function requires RCU read locking, it doesn't require the | |
3090 | * whole traversal to be contained in a single RCU critical section. This | |
3091 | * function will return the correct next descendant as long as both @pos | |
492eb21b | 3092 | * and @root are accessible and @pos is a descendant of @root. |
574bd9f7 | 3093 | */ |
492eb21b TH |
3094 | struct cgroup_subsys_state * |
3095 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
3096 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3097 | { |
492eb21b | 3098 | struct cgroup_subsys_state *next; |
574bd9f7 TH |
3099 | |
3100 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3101 | ||
492eb21b | 3102 | /* if first iteration, pretend we just visited @root */ |
7805d000 | 3103 | if (!pos) |
492eb21b | 3104 | pos = root; |
574bd9f7 TH |
3105 | |
3106 | /* visit the first child if exists */ | |
492eb21b | 3107 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
3108 | if (next) |
3109 | return next; | |
3110 | ||
3111 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b TH |
3112 | while (pos != root) { |
3113 | next = css_next_child(pos, css_parent(pos)); | |
75501a6d | 3114 | if (next) |
574bd9f7 | 3115 | return next; |
492eb21b | 3116 | pos = css_parent(pos); |
7805d000 | 3117 | } |
574bd9f7 TH |
3118 | |
3119 | return NULL; | |
3120 | } | |
492eb21b | 3121 | EXPORT_SYMBOL_GPL(css_next_descendant_pre); |
574bd9f7 | 3122 | |
12a9d2fe | 3123 | /** |
492eb21b TH |
3124 | * css_rightmost_descendant - return the rightmost descendant of a css |
3125 | * @pos: css of interest | |
12a9d2fe | 3126 | * |
492eb21b TH |
3127 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
3128 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 3129 | * subtree of @pos. |
75501a6d TH |
3130 | * |
3131 | * While this function requires RCU read locking, it doesn't require the | |
3132 | * whole traversal to be contained in a single RCU critical section. This | |
3133 | * function will return the correct rightmost descendant as long as @pos is | |
3134 | * accessible. | |
12a9d2fe | 3135 | */ |
492eb21b TH |
3136 | struct cgroup_subsys_state * |
3137 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 3138 | { |
492eb21b | 3139 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe TH |
3140 | |
3141 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3142 | ||
3143 | do { | |
3144 | last = pos; | |
3145 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3146 | pos = NULL; | |
492eb21b | 3147 | css_for_each_child(tmp, last) |
12a9d2fe TH |
3148 | pos = tmp; |
3149 | } while (pos); | |
3150 | ||
3151 | return last; | |
3152 | } | |
492eb21b | 3153 | EXPORT_SYMBOL_GPL(css_rightmost_descendant); |
12a9d2fe | 3154 | |
492eb21b TH |
3155 | static struct cgroup_subsys_state * |
3156 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 3157 | { |
492eb21b | 3158 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
3159 | |
3160 | do { | |
3161 | last = pos; | |
492eb21b | 3162 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
3163 | } while (pos); |
3164 | ||
3165 | return last; | |
3166 | } | |
3167 | ||
3168 | /** | |
492eb21b | 3169 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 3170 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3171 | * @root: css whose descendants to walk |
574bd9f7 | 3172 | * |
492eb21b TH |
3173 | * To be used by css_for_each_descendant_post(). Find the next descendant |
3174 | * to visit for post-order traversal of @root's descendants. | |
75501a6d TH |
3175 | * |
3176 | * While this function requires RCU read locking, it doesn't require the | |
3177 | * whole traversal to be contained in a single RCU critical section. This | |
3178 | * function will return the correct next descendant as long as both @pos | |
3179 | * and @cgroup are accessible and @pos is a descendant of @cgroup. | |
574bd9f7 | 3180 | */ |
492eb21b TH |
3181 | struct cgroup_subsys_state * |
3182 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
3183 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3184 | { |
492eb21b | 3185 | struct cgroup_subsys_state *next; |
574bd9f7 TH |
3186 | |
3187 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3188 | ||
3189 | /* if first iteration, visit the leftmost descendant */ | |
3190 | if (!pos) { | |
492eb21b TH |
3191 | next = css_leftmost_descendant(root); |
3192 | return next != root ? next : NULL; | |
574bd9f7 TH |
3193 | } |
3194 | ||
3195 | /* if there's an unvisited sibling, visit its leftmost descendant */ | |
492eb21b | 3196 | next = css_next_child(pos, css_parent(pos)); |
75501a6d | 3197 | if (next) |
492eb21b | 3198 | return css_leftmost_descendant(next); |
574bd9f7 TH |
3199 | |
3200 | /* no sibling left, visit parent */ | |
492eb21b TH |
3201 | next = css_parent(pos); |
3202 | return next != root ? next : NULL; | |
574bd9f7 | 3203 | } |
492eb21b | 3204 | EXPORT_SYMBOL_GPL(css_next_descendant_post); |
574bd9f7 | 3205 | |
0942eeee TH |
3206 | /** |
3207 | * cgroup_advance_task_iter - advance a task itererator to the next css_set | |
0942eeee TH |
3208 | * @it: the iterator to advance |
3209 | * | |
3210 | * Advance @it to the next css_set to walk. | |
d515876e | 3211 | */ |
c59cd3d8 | 3212 | static void cgroup_advance_task_iter(struct cgroup_task_iter *it) |
d515876e TH |
3213 | { |
3214 | struct list_head *l = it->cset_link; | |
3215 | struct cgrp_cset_link *link; | |
3216 | struct css_set *cset; | |
3217 | ||
3218 | /* Advance to the next non-empty css_set */ | |
3219 | do { | |
3220 | l = l->next; | |
c59cd3d8 | 3221 | if (l == &it->origin_cgrp->cset_links) { |
d515876e TH |
3222 | it->cset_link = NULL; |
3223 | return; | |
3224 | } | |
3225 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
3226 | cset = link->cset; | |
3227 | } while (list_empty(&cset->tasks)); | |
3228 | it->cset_link = l; | |
3229 | it->task = cset->tasks.next; | |
3230 | } | |
3231 | ||
0942eeee TH |
3232 | /** |
3233 | * cgroup_task_iter_start - initiate task iteration | |
3234 | * @cgrp: the cgroup to walk tasks of | |
3235 | * @it: the task iterator to use | |
3236 | * | |
3237 | * Initiate iteration through the tasks of @cgrp. The caller can call | |
3238 | * cgroup_task_iter_next() to walk through the tasks until the function | |
3239 | * returns NULL. On completion of iteration, cgroup_task_iter_end() must | |
3240 | * be called. | |
3241 | * | |
3242 | * Note that this function acquires a lock which is released when the | |
3243 | * iteration finishes. The caller can't sleep while iteration is in | |
3244 | * progress. | |
3245 | */ | |
3246 | void cgroup_task_iter_start(struct cgroup *cgrp, struct cgroup_task_iter *it) | |
c6ca5750 | 3247 | __acquires(css_set_lock) |
817929ec PM |
3248 | { |
3249 | /* | |
3250 | * The first time anyone tries to iterate across a cgroup, | |
3251 | * we need to enable the list linking each css_set to its | |
3252 | * tasks, and fix up all existing tasks. | |
3253 | */ | |
31a7df01 CW |
3254 | if (!use_task_css_set_links) |
3255 | cgroup_enable_task_cg_lists(); | |
3256 | ||
817929ec | 3257 | read_lock(&css_set_lock); |
c59cd3d8 TH |
3258 | |
3259 | it->origin_cgrp = cgrp; | |
69d0206c | 3260 | it->cset_link = &cgrp->cset_links; |
c59cd3d8 TH |
3261 | |
3262 | cgroup_advance_task_iter(it); | |
817929ec PM |
3263 | } |
3264 | ||
0942eeee TH |
3265 | /** |
3266 | * cgroup_task_iter_next - return the next task for the iterator | |
0942eeee TH |
3267 | * @it: the task iterator being iterated |
3268 | * | |
3269 | * The "next" function for task iteration. @it should have been | |
3270 | * initialized via cgroup_task_iter_start(). Returns NULL when the | |
3271 | * iteration reaches the end. | |
3272 | */ | |
c59cd3d8 | 3273 | struct task_struct *cgroup_task_iter_next(struct cgroup_task_iter *it) |
817929ec PM |
3274 | { |
3275 | struct task_struct *res; | |
3276 | struct list_head *l = it->task; | |
69d0206c | 3277 | struct cgrp_cset_link *link; |
817929ec PM |
3278 | |
3279 | /* If the iterator cg is NULL, we have no tasks */ | |
69d0206c | 3280 | if (!it->cset_link) |
817929ec PM |
3281 | return NULL; |
3282 | res = list_entry(l, struct task_struct, cg_list); | |
3283 | /* Advance iterator to find next entry */ | |
3284 | l = l->next; | |
69d0206c TH |
3285 | link = list_entry(it->cset_link, struct cgrp_cset_link, cset_link); |
3286 | if (l == &link->cset->tasks) { | |
0942eeee TH |
3287 | /* |
3288 | * We reached the end of this task list - move on to the | |
3289 | * next cgrp_cset_link. | |
3290 | */ | |
c59cd3d8 | 3291 | cgroup_advance_task_iter(it); |
817929ec PM |
3292 | } else { |
3293 | it->task = l; | |
3294 | } | |
3295 | return res; | |
3296 | } | |
3297 | ||
0942eeee TH |
3298 | /** |
3299 | * cgroup_task_iter_end - finish task iteration | |
0942eeee TH |
3300 | * @it: the task iterator to finish |
3301 | * | |
3302 | * Finish task iteration started by cgroup_task_iter_start(). | |
3303 | */ | |
c59cd3d8 | 3304 | void cgroup_task_iter_end(struct cgroup_task_iter *it) |
c6ca5750 | 3305 | __releases(css_set_lock) |
817929ec PM |
3306 | { |
3307 | read_unlock(&css_set_lock); | |
3308 | } | |
3309 | ||
31a7df01 CW |
3310 | static inline int started_after_time(struct task_struct *t1, |
3311 | struct timespec *time, | |
3312 | struct task_struct *t2) | |
3313 | { | |
3314 | int start_diff = timespec_compare(&t1->start_time, time); | |
3315 | if (start_diff > 0) { | |
3316 | return 1; | |
3317 | } else if (start_diff < 0) { | |
3318 | return 0; | |
3319 | } else { | |
3320 | /* | |
3321 | * Arbitrarily, if two processes started at the same | |
3322 | * time, we'll say that the lower pointer value | |
3323 | * started first. Note that t2 may have exited by now | |
3324 | * so this may not be a valid pointer any longer, but | |
3325 | * that's fine - it still serves to distinguish | |
3326 | * between two tasks started (effectively) simultaneously. | |
3327 | */ | |
3328 | return t1 > t2; | |
3329 | } | |
3330 | } | |
3331 | ||
3332 | /* | |
3333 | * This function is a callback from heap_insert() and is used to order | |
3334 | * the heap. | |
3335 | * In this case we order the heap in descending task start time. | |
3336 | */ | |
3337 | static inline int started_after(void *p1, void *p2) | |
3338 | { | |
3339 | struct task_struct *t1 = p1; | |
3340 | struct task_struct *t2 = p2; | |
3341 | return started_after_time(t1, &t2->start_time, t2); | |
3342 | } | |
3343 | ||
3344 | /** | |
3345 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
e535837b TH |
3346 | * @cgrp: the cgroup to iterate tasks of |
3347 | * @test: optional test callback | |
3348 | * @process: process callback | |
3349 | * @data: data passed to @test and @process | |
3350 | * @heap: optional pre-allocated heap used for task iteration | |
31a7df01 | 3351 | * |
e535837b TH |
3352 | * Iterate through all the tasks in a cgroup, calling @test for each, and |
3353 | * if it returns %true, call @process for it also. | |
31a7df01 | 3354 | * |
e535837b TH |
3355 | * @test may be NULL, meaning always true (select all tasks), which |
3356 | * effectively duplicates cgroup_task_iter_{start,next,end}() but does not | |
3357 | * lock css_set_lock for the call to @process. | |
3358 | * | |
3359 | * It is guaranteed that @process will act on every task that is a member | |
3360 | * of @cgrp for the duration of this call. This function may or may not | |
3361 | * call @process for tasks that exit or move to a different cgroup during | |
3362 | * the call, or are forked or move into the cgroup during the call. | |
3363 | * | |
3364 | * Note that @test may be called with locks held, and may in some | |
3365 | * situations be called multiple times for the same task, so it should be | |
3366 | * cheap. | |
3367 | * | |
3368 | * If @heap is non-NULL, a heap has been pre-allocated and will be used for | |
3369 | * heap operations (and its "gt" member will be overwritten), else a | |
3370 | * temporary heap will be used (allocation of which may cause this function | |
3371 | * to fail). | |
31a7df01 | 3372 | */ |
e535837b TH |
3373 | int cgroup_scan_tasks(struct cgroup *cgrp, |
3374 | bool (*test)(struct task_struct *, void *), | |
3375 | void (*process)(struct task_struct *, void *), | |
3376 | void *data, struct ptr_heap *heap) | |
31a7df01 CW |
3377 | { |
3378 | int retval, i; | |
0942eeee | 3379 | struct cgroup_task_iter it; |
31a7df01 CW |
3380 | struct task_struct *p, *dropped; |
3381 | /* Never dereference latest_task, since it's not refcounted */ | |
3382 | struct task_struct *latest_task = NULL; | |
3383 | struct ptr_heap tmp_heap; | |
31a7df01 CW |
3384 | struct timespec latest_time = { 0, 0 }; |
3385 | ||
e535837b | 3386 | if (heap) { |
31a7df01 | 3387 | /* The caller supplied our heap and pre-allocated its memory */ |
31a7df01 CW |
3388 | heap->gt = &started_after; |
3389 | } else { | |
3390 | /* We need to allocate our own heap memory */ | |
3391 | heap = &tmp_heap; | |
3392 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
3393 | if (retval) | |
3394 | /* cannot allocate the heap */ | |
3395 | return retval; | |
3396 | } | |
3397 | ||
3398 | again: | |
3399 | /* | |
e535837b TH |
3400 | * Scan tasks in the cgroup, using the @test callback to determine |
3401 | * which are of interest, and invoking @process callback on the | |
3402 | * ones which need an update. Since we don't want to hold any | |
3403 | * locks during the task updates, gather tasks to be processed in a | |
3404 | * heap structure. The heap is sorted by descending task start | |
3405 | * time. If the statically-sized heap fills up, we overflow tasks | |
3406 | * that started later, and in future iterations only consider tasks | |
3407 | * that started after the latest task in the previous pass. This | |
31a7df01 CW |
3408 | * guarantees forward progress and that we don't miss any tasks. |
3409 | */ | |
3410 | heap->size = 0; | |
e535837b | 3411 | cgroup_task_iter_start(cgrp, &it); |
c59cd3d8 | 3412 | while ((p = cgroup_task_iter_next(&it))) { |
31a7df01 CW |
3413 | /* |
3414 | * Only affect tasks that qualify per the caller's callback, | |
3415 | * if he provided one | |
3416 | */ | |
e535837b | 3417 | if (test && !test(p, data)) |
31a7df01 CW |
3418 | continue; |
3419 | /* | |
3420 | * Only process tasks that started after the last task | |
3421 | * we processed | |
3422 | */ | |
3423 | if (!started_after_time(p, &latest_time, latest_task)) | |
3424 | continue; | |
3425 | dropped = heap_insert(heap, p); | |
3426 | if (dropped == NULL) { | |
3427 | /* | |
3428 | * The new task was inserted; the heap wasn't | |
3429 | * previously full | |
3430 | */ | |
3431 | get_task_struct(p); | |
3432 | } else if (dropped != p) { | |
3433 | /* | |
3434 | * The new task was inserted, and pushed out a | |
3435 | * different task | |
3436 | */ | |
3437 | get_task_struct(p); | |
3438 | put_task_struct(dropped); | |
3439 | } | |
3440 | /* | |
3441 | * Else the new task was newer than anything already in | |
3442 | * the heap and wasn't inserted | |
3443 | */ | |
3444 | } | |
c59cd3d8 | 3445 | cgroup_task_iter_end(&it); |
31a7df01 CW |
3446 | |
3447 | if (heap->size) { | |
3448 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 3449 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 3450 | if (i == 0) { |
4fe91d51 PJ |
3451 | latest_time = q->start_time; |
3452 | latest_task = q; | |
31a7df01 CW |
3453 | } |
3454 | /* Process the task per the caller's callback */ | |
e535837b | 3455 | process(q, data); |
4fe91d51 | 3456 | put_task_struct(q); |
31a7df01 CW |
3457 | } |
3458 | /* | |
3459 | * If we had to process any tasks at all, scan again | |
3460 | * in case some of them were in the middle of forking | |
3461 | * children that didn't get processed. | |
3462 | * Not the most efficient way to do it, but it avoids | |
3463 | * having to take callback_mutex in the fork path | |
3464 | */ | |
3465 | goto again; | |
3466 | } | |
3467 | if (heap == &tmp_heap) | |
3468 | heap_free(&tmp_heap); | |
3469 | return 0; | |
3470 | } | |
3471 | ||
e535837b | 3472 | static void cgroup_transfer_one_task(struct task_struct *task, void *data) |
8cc99345 | 3473 | { |
e535837b | 3474 | struct cgroup *new_cgroup = data; |
8cc99345 | 3475 | |
47cfcd09 | 3476 | mutex_lock(&cgroup_mutex); |
8cc99345 | 3477 | cgroup_attach_task(new_cgroup, task, false); |
47cfcd09 | 3478 | mutex_unlock(&cgroup_mutex); |
8cc99345 TH |
3479 | } |
3480 | ||
3481 | /** | |
3482 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another | |
3483 | * @to: cgroup to which the tasks will be moved | |
3484 | * @from: cgroup in which the tasks currently reside | |
3485 | */ | |
3486 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) | |
3487 | { | |
e535837b | 3488 | return cgroup_scan_tasks(from, NULL, cgroup_transfer_one_task, to, NULL); |
8cc99345 TH |
3489 | } |
3490 | ||
bbcb81d0 | 3491 | /* |
102a775e | 3492 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3493 | * |
3494 | * Reading this file can return large amounts of data if a cgroup has | |
3495 | * *lots* of attached tasks. So it may need several calls to read(), | |
3496 | * but we cannot guarantee that the information we produce is correct | |
3497 | * unless we produce it entirely atomically. | |
3498 | * | |
bbcb81d0 | 3499 | */ |
bbcb81d0 | 3500 | |
24528255 LZ |
3501 | /* which pidlist file are we talking about? */ |
3502 | enum cgroup_filetype { | |
3503 | CGROUP_FILE_PROCS, | |
3504 | CGROUP_FILE_TASKS, | |
3505 | }; | |
3506 | ||
3507 | /* | |
3508 | * A pidlist is a list of pids that virtually represents the contents of one | |
3509 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3510 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3511 | * to the cgroup. | |
3512 | */ | |
3513 | struct cgroup_pidlist { | |
3514 | /* | |
3515 | * used to find which pidlist is wanted. doesn't change as long as | |
3516 | * this particular list stays in the list. | |
3517 | */ | |
3518 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3519 | /* array of xids */ | |
3520 | pid_t *list; | |
3521 | /* how many elements the above list has */ | |
3522 | int length; | |
3523 | /* how many files are using the current array */ | |
3524 | int use_count; | |
3525 | /* each of these stored in a list by its cgroup */ | |
3526 | struct list_head links; | |
3527 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3528 | struct cgroup *owner; | |
3529 | /* protects the other fields */ | |
b395890a | 3530 | struct rw_semaphore rwsem; |
24528255 LZ |
3531 | }; |
3532 | ||
d1d9fd33 BB |
3533 | /* |
3534 | * The following two functions "fix" the issue where there are more pids | |
3535 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3536 | * TODO: replace with a kernel-wide solution to this problem | |
3537 | */ | |
3538 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3539 | static void *pidlist_allocate(int count) | |
3540 | { | |
3541 | if (PIDLIST_TOO_LARGE(count)) | |
3542 | return vmalloc(count * sizeof(pid_t)); | |
3543 | else | |
3544 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3545 | } | |
3546 | static void pidlist_free(void *p) | |
3547 | { | |
3548 | if (is_vmalloc_addr(p)) | |
3549 | vfree(p); | |
3550 | else | |
3551 | kfree(p); | |
3552 | } | |
d1d9fd33 | 3553 | |
bbcb81d0 | 3554 | /* |
102a775e | 3555 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 3556 | * Returns the number of unique elements. |
bbcb81d0 | 3557 | */ |
6ee211ad | 3558 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 3559 | { |
102a775e | 3560 | int src, dest = 1; |
102a775e BB |
3561 | |
3562 | /* | |
3563 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3564 | * edge cases first; no work needs to be done for either | |
3565 | */ | |
3566 | if (length == 0 || length == 1) | |
3567 | return length; | |
3568 | /* src and dest walk down the list; dest counts unique elements */ | |
3569 | for (src = 1; src < length; src++) { | |
3570 | /* find next unique element */ | |
3571 | while (list[src] == list[src-1]) { | |
3572 | src++; | |
3573 | if (src == length) | |
3574 | goto after; | |
3575 | } | |
3576 | /* dest always points to where the next unique element goes */ | |
3577 | list[dest] = list[src]; | |
3578 | dest++; | |
3579 | } | |
3580 | after: | |
102a775e BB |
3581 | return dest; |
3582 | } | |
3583 | ||
3584 | static int cmppid(const void *a, const void *b) | |
3585 | { | |
3586 | return *(pid_t *)a - *(pid_t *)b; | |
3587 | } | |
3588 | ||
72a8cb30 BB |
3589 | /* |
3590 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3591 | * returns with the lock on that pidlist already held, and takes care | |
3592 | * of the use count, or returns NULL with no locks held if we're out of | |
3593 | * memory. | |
3594 | */ | |
3595 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
3596 | enum cgroup_filetype type) | |
3597 | { | |
3598 | struct cgroup_pidlist *l; | |
3599 | /* don't need task_nsproxy() if we're looking at ourself */ | |
17cf22c3 | 3600 | struct pid_namespace *ns = task_active_pid_ns(current); |
b70cc5fd | 3601 | |
72a8cb30 | 3602 | /* |
b395890a | 3603 | * We can't drop the pidlist_mutex before taking the l->rwsem in case |
72a8cb30 BB |
3604 | * the last ref-holder is trying to remove l from the list at the same |
3605 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
3606 | * list we find out from under us - compare release_pid_array(). | |
3607 | */ | |
3608 | mutex_lock(&cgrp->pidlist_mutex); | |
3609 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
3610 | if (l->key.type == type && l->key.ns == ns) { | |
72a8cb30 | 3611 | /* make sure l doesn't vanish out from under us */ |
b395890a | 3612 | down_write(&l->rwsem); |
72a8cb30 | 3613 | mutex_unlock(&cgrp->pidlist_mutex); |
72a8cb30 BB |
3614 | return l; |
3615 | } | |
3616 | } | |
3617 | /* entry not found; create a new one */ | |
f4f4be2b | 3618 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
72a8cb30 BB |
3619 | if (!l) { |
3620 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3621 | return l; |
3622 | } | |
b395890a LZ |
3623 | init_rwsem(&l->rwsem); |
3624 | down_write(&l->rwsem); | |
72a8cb30 | 3625 | l->key.type = type; |
b70cc5fd | 3626 | l->key.ns = get_pid_ns(ns); |
72a8cb30 BB |
3627 | l->owner = cgrp; |
3628 | list_add(&l->links, &cgrp->pidlists); | |
3629 | mutex_unlock(&cgrp->pidlist_mutex); | |
3630 | return l; | |
3631 | } | |
3632 | ||
102a775e BB |
3633 | /* |
3634 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3635 | */ | |
72a8cb30 BB |
3636 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3637 | struct cgroup_pidlist **lp) | |
102a775e BB |
3638 | { |
3639 | pid_t *array; | |
3640 | int length; | |
3641 | int pid, n = 0; /* used for populating the array */ | |
0942eeee | 3642 | struct cgroup_task_iter it; |
817929ec | 3643 | struct task_struct *tsk; |
102a775e BB |
3644 | struct cgroup_pidlist *l; |
3645 | ||
3646 | /* | |
3647 | * If cgroup gets more users after we read count, we won't have | |
3648 | * enough space - tough. This race is indistinguishable to the | |
3649 | * caller from the case that the additional cgroup users didn't | |
3650 | * show up until sometime later on. | |
3651 | */ | |
3652 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3653 | array = pidlist_allocate(length); |
102a775e BB |
3654 | if (!array) |
3655 | return -ENOMEM; | |
3656 | /* now, populate the array */ | |
0942eeee | 3657 | cgroup_task_iter_start(cgrp, &it); |
c59cd3d8 | 3658 | while ((tsk = cgroup_task_iter_next(&it))) { |
102a775e | 3659 | if (unlikely(n == length)) |
817929ec | 3660 | break; |
102a775e | 3661 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3662 | if (type == CGROUP_FILE_PROCS) |
3663 | pid = task_tgid_vnr(tsk); | |
3664 | else | |
3665 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3666 | if (pid > 0) /* make sure to only use valid results */ |
3667 | array[n++] = pid; | |
817929ec | 3668 | } |
c59cd3d8 | 3669 | cgroup_task_iter_end(&it); |
102a775e BB |
3670 | length = n; |
3671 | /* now sort & (if procs) strip out duplicates */ | |
3672 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3673 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 3674 | length = pidlist_uniq(array, length); |
72a8cb30 BB |
3675 | l = cgroup_pidlist_find(cgrp, type); |
3676 | if (!l) { | |
d1d9fd33 | 3677 | pidlist_free(array); |
72a8cb30 | 3678 | return -ENOMEM; |
102a775e | 3679 | } |
72a8cb30 | 3680 | /* store array, freeing old if necessary - lock already held */ |
d1d9fd33 | 3681 | pidlist_free(l->list); |
102a775e BB |
3682 | l->list = array; |
3683 | l->length = length; | |
3684 | l->use_count++; | |
b395890a | 3685 | up_write(&l->rwsem); |
72a8cb30 | 3686 | *lp = l; |
102a775e | 3687 | return 0; |
bbcb81d0 PM |
3688 | } |
3689 | ||
846c7bb0 | 3690 | /** |
a043e3b2 | 3691 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3692 | * @stats: cgroupstats to fill information into |
3693 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3694 | * been requested. | |
a043e3b2 LZ |
3695 | * |
3696 | * Build and fill cgroupstats so that taskstats can export it to user | |
3697 | * space. | |
846c7bb0 BS |
3698 | */ |
3699 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3700 | { | |
3701 | int ret = -EINVAL; | |
bd89aabc | 3702 | struct cgroup *cgrp; |
0942eeee | 3703 | struct cgroup_task_iter it; |
846c7bb0 | 3704 | struct task_struct *tsk; |
33d283be | 3705 | |
846c7bb0 | 3706 | /* |
33d283be LZ |
3707 | * Validate dentry by checking the superblock operations, |
3708 | * and make sure it's a directory. | |
846c7bb0 | 3709 | */ |
33d283be LZ |
3710 | if (dentry->d_sb->s_op != &cgroup_ops || |
3711 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
3712 | goto err; |
3713 | ||
3714 | ret = 0; | |
bd89aabc | 3715 | cgrp = dentry->d_fsdata; |
846c7bb0 | 3716 | |
0942eeee | 3717 | cgroup_task_iter_start(cgrp, &it); |
c59cd3d8 | 3718 | while ((tsk = cgroup_task_iter_next(&it))) { |
846c7bb0 BS |
3719 | switch (tsk->state) { |
3720 | case TASK_RUNNING: | |
3721 | stats->nr_running++; | |
3722 | break; | |
3723 | case TASK_INTERRUPTIBLE: | |
3724 | stats->nr_sleeping++; | |
3725 | break; | |
3726 | case TASK_UNINTERRUPTIBLE: | |
3727 | stats->nr_uninterruptible++; | |
3728 | break; | |
3729 | case TASK_STOPPED: | |
3730 | stats->nr_stopped++; | |
3731 | break; | |
3732 | default: | |
3733 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3734 | stats->nr_io_wait++; | |
3735 | break; | |
3736 | } | |
3737 | } | |
c59cd3d8 | 3738 | cgroup_task_iter_end(&it); |
846c7bb0 | 3739 | |
846c7bb0 BS |
3740 | err: |
3741 | return ret; | |
3742 | } | |
3743 | ||
8f3ff208 | 3744 | |
bbcb81d0 | 3745 | /* |
102a775e | 3746 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3747 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3748 | * in the cgroup->l->list array. |
bbcb81d0 | 3749 | */ |
cc31edce | 3750 | |
102a775e | 3751 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3752 | { |
cc31edce PM |
3753 | /* |
3754 | * Initially we receive a position value that corresponds to | |
3755 | * one more than the last pid shown (or 0 on the first call or | |
3756 | * after a seek to the start). Use a binary-search to find the | |
3757 | * next pid to display, if any | |
3758 | */ | |
102a775e | 3759 | struct cgroup_pidlist *l = s->private; |
cc31edce PM |
3760 | int index = 0, pid = *pos; |
3761 | int *iter; | |
3762 | ||
b395890a | 3763 | down_read(&l->rwsem); |
cc31edce | 3764 | if (pid) { |
102a775e | 3765 | int end = l->length; |
20777766 | 3766 | |
cc31edce PM |
3767 | while (index < end) { |
3768 | int mid = (index + end) / 2; | |
102a775e | 3769 | if (l->list[mid] == pid) { |
cc31edce PM |
3770 | index = mid; |
3771 | break; | |
102a775e | 3772 | } else if (l->list[mid] <= pid) |
cc31edce PM |
3773 | index = mid + 1; |
3774 | else | |
3775 | end = mid; | |
3776 | } | |
3777 | } | |
3778 | /* If we're off the end of the array, we're done */ | |
102a775e | 3779 | if (index >= l->length) |
cc31edce PM |
3780 | return NULL; |
3781 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3782 | iter = l->list + index; |
cc31edce PM |
3783 | *pos = *iter; |
3784 | return iter; | |
3785 | } | |
3786 | ||
102a775e | 3787 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3788 | { |
102a775e | 3789 | struct cgroup_pidlist *l = s->private; |
b395890a | 3790 | up_read(&l->rwsem); |
cc31edce PM |
3791 | } |
3792 | ||
102a775e | 3793 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3794 | { |
102a775e BB |
3795 | struct cgroup_pidlist *l = s->private; |
3796 | pid_t *p = v; | |
3797 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3798 | /* |
3799 | * Advance to the next pid in the array. If this goes off the | |
3800 | * end, we're done | |
3801 | */ | |
3802 | p++; | |
3803 | if (p >= end) { | |
3804 | return NULL; | |
3805 | } else { | |
3806 | *pos = *p; | |
3807 | return p; | |
3808 | } | |
3809 | } | |
3810 | ||
102a775e | 3811 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3812 | { |
3813 | return seq_printf(s, "%d\n", *(int *)v); | |
3814 | } | |
bbcb81d0 | 3815 | |
102a775e BB |
3816 | /* |
3817 | * seq_operations functions for iterating on pidlists through seq_file - | |
3818 | * independent of whether it's tasks or procs | |
3819 | */ | |
3820 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3821 | .start = cgroup_pidlist_start, | |
3822 | .stop = cgroup_pidlist_stop, | |
3823 | .next = cgroup_pidlist_next, | |
3824 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3825 | }; |
3826 | ||
102a775e | 3827 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
cc31edce | 3828 | { |
72a8cb30 BB |
3829 | /* |
3830 | * the case where we're the last user of this particular pidlist will | |
3831 | * have us remove it from the cgroup's list, which entails taking the | |
3832 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
3833 | * pidlist_mutex, we have to take pidlist_mutex first. | |
3834 | */ | |
3835 | mutex_lock(&l->owner->pidlist_mutex); | |
b395890a | 3836 | down_write(&l->rwsem); |
102a775e BB |
3837 | BUG_ON(!l->use_count); |
3838 | if (!--l->use_count) { | |
72a8cb30 BB |
3839 | /* we're the last user if refcount is 0; remove and free */ |
3840 | list_del(&l->links); | |
3841 | mutex_unlock(&l->owner->pidlist_mutex); | |
d1d9fd33 | 3842 | pidlist_free(l->list); |
72a8cb30 | 3843 | put_pid_ns(l->key.ns); |
b395890a | 3844 | up_write(&l->rwsem); |
72a8cb30 BB |
3845 | kfree(l); |
3846 | return; | |
cc31edce | 3847 | } |
72a8cb30 | 3848 | mutex_unlock(&l->owner->pidlist_mutex); |
b395890a | 3849 | up_write(&l->rwsem); |
bbcb81d0 PM |
3850 | } |
3851 | ||
102a775e | 3852 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
cc31edce | 3853 | { |
102a775e | 3854 | struct cgroup_pidlist *l; |
cc31edce PM |
3855 | if (!(file->f_mode & FMODE_READ)) |
3856 | return 0; | |
102a775e BB |
3857 | /* |
3858 | * the seq_file will only be initialized if the file was opened for | |
3859 | * reading; hence we check if it's not null only in that case. | |
3860 | */ | |
3861 | l = ((struct seq_file *)file->private_data)->private; | |
3862 | cgroup_release_pid_array(l); | |
cc31edce PM |
3863 | return seq_release(inode, file); |
3864 | } | |
3865 | ||
102a775e | 3866 | static const struct file_operations cgroup_pidlist_operations = { |
cc31edce PM |
3867 | .read = seq_read, |
3868 | .llseek = seq_lseek, | |
3869 | .write = cgroup_file_write, | |
102a775e | 3870 | .release = cgroup_pidlist_release, |
cc31edce PM |
3871 | }; |
3872 | ||
bbcb81d0 | 3873 | /* |
102a775e BB |
3874 | * The following functions handle opens on a file that displays a pidlist |
3875 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3876 | * in the cgroup. | |
bbcb81d0 | 3877 | */ |
102a775e | 3878 | /* helper function for the two below it */ |
72a8cb30 | 3879 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
bbcb81d0 | 3880 | { |
bd89aabc | 3881 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
72a8cb30 | 3882 | struct cgroup_pidlist *l; |
cc31edce | 3883 | int retval; |
bbcb81d0 | 3884 | |
cc31edce | 3885 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
3886 | if (!(file->f_mode & FMODE_READ)) |
3887 | return 0; | |
3888 | ||
102a775e | 3889 | /* have the array populated */ |
72a8cb30 | 3890 | retval = pidlist_array_load(cgrp, type, &l); |
102a775e BB |
3891 | if (retval) |
3892 | return retval; | |
3893 | /* configure file information */ | |
3894 | file->f_op = &cgroup_pidlist_operations; | |
cc31edce | 3895 | |
102a775e | 3896 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
cc31edce | 3897 | if (retval) { |
102a775e | 3898 | cgroup_release_pid_array(l); |
cc31edce | 3899 | return retval; |
bbcb81d0 | 3900 | } |
102a775e | 3901 | ((struct seq_file *)file->private_data)->private = l; |
bbcb81d0 PM |
3902 | return 0; |
3903 | } | |
102a775e BB |
3904 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3905 | { | |
72a8cb30 | 3906 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
102a775e BB |
3907 | } |
3908 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3909 | { | |
72a8cb30 | 3910 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
102a775e | 3911 | } |
bbcb81d0 | 3912 | |
182446d0 TH |
3913 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
3914 | struct cftype *cft) | |
81a6a5cd | 3915 | { |
182446d0 | 3916 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
3917 | } |
3918 | ||
182446d0 TH |
3919 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
3920 | struct cftype *cft, u64 val) | |
6379c106 | 3921 | { |
182446d0 | 3922 | clear_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
6379c106 | 3923 | if (val) |
182446d0 | 3924 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 3925 | else |
182446d0 | 3926 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
3927 | return 0; |
3928 | } | |
3929 | ||
1c8158ee LZ |
3930 | /* |
3931 | * When dput() is called asynchronously, if umount has been done and | |
3932 | * then deactivate_super() in cgroup_free_fn() kills the superblock, | |
3933 | * there's a small window that vfs will see the root dentry with non-zero | |
3934 | * refcnt and trigger BUG(). | |
3935 | * | |
3936 | * That's why we hold a reference before dput() and drop it right after. | |
3937 | */ | |
3938 | static void cgroup_dput(struct cgroup *cgrp) | |
3939 | { | |
3940 | struct super_block *sb = cgrp->root->sb; | |
3941 | ||
3942 | atomic_inc(&sb->s_active); | |
3943 | dput(cgrp->dentry); | |
3944 | deactivate_super(sb); | |
3945 | } | |
3946 | ||
0dea1168 KS |
3947 | /* |
3948 | * Unregister event and free resources. | |
3949 | * | |
3950 | * Gets called from workqueue. | |
3951 | */ | |
3952 | static void cgroup_event_remove(struct work_struct *work) | |
3953 | { | |
3954 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3955 | remove); | |
3956 | struct cgroup *cgrp = event->cgrp; | |
3957 | ||
810cbee4 LZ |
3958 | remove_wait_queue(event->wqh, &event->wait); |
3959 | ||
0dea1168 KS |
3960 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3961 | ||
810cbee4 LZ |
3962 | /* Notify userspace the event is going away. */ |
3963 | eventfd_signal(event->eventfd, 1); | |
3964 | ||
0dea1168 | 3965 | eventfd_ctx_put(event->eventfd); |
0dea1168 | 3966 | kfree(event); |
1c8158ee | 3967 | cgroup_dput(cgrp); |
0dea1168 KS |
3968 | } |
3969 | ||
3970 | /* | |
3971 | * Gets called on POLLHUP on eventfd when user closes it. | |
3972 | * | |
3973 | * Called with wqh->lock held and interrupts disabled. | |
3974 | */ | |
3975 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3976 | int sync, void *key) | |
3977 | { | |
3978 | struct cgroup_event *event = container_of(wait, | |
3979 | struct cgroup_event, wait); | |
3980 | struct cgroup *cgrp = event->cgrp; | |
3981 | unsigned long flags = (unsigned long)key; | |
3982 | ||
3983 | if (flags & POLLHUP) { | |
0dea1168 | 3984 | /* |
810cbee4 LZ |
3985 | * If the event has been detached at cgroup removal, we |
3986 | * can simply return knowing the other side will cleanup | |
3987 | * for us. | |
3988 | * | |
3989 | * We can't race against event freeing since the other | |
3990 | * side will require wqh->lock via remove_wait_queue(), | |
3991 | * which we hold. | |
0dea1168 | 3992 | */ |
810cbee4 LZ |
3993 | spin_lock(&cgrp->event_list_lock); |
3994 | if (!list_empty(&event->list)) { | |
3995 | list_del_init(&event->list); | |
3996 | /* | |
3997 | * We are in atomic context, but cgroup_event_remove() | |
3998 | * may sleep, so we have to call it in workqueue. | |
3999 | */ | |
4000 | schedule_work(&event->remove); | |
4001 | } | |
4002 | spin_unlock(&cgrp->event_list_lock); | |
0dea1168 KS |
4003 | } |
4004 | ||
4005 | return 0; | |
4006 | } | |
4007 | ||
4008 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
4009 | wait_queue_head_t *wqh, poll_table *pt) | |
4010 | { | |
4011 | struct cgroup_event *event = container_of(pt, | |
4012 | struct cgroup_event, pt); | |
4013 | ||
4014 | event->wqh = wqh; | |
4015 | add_wait_queue(wqh, &event->wait); | |
4016 | } | |
4017 | ||
4018 | /* | |
4019 | * Parse input and register new cgroup event handler. | |
4020 | * | |
4021 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
4022 | * Interpretation of args is defined by control file implementation. | |
4023 | */ | |
182446d0 TH |
4024 | static int cgroup_write_event_control(struct cgroup_subsys_state *css, |
4025 | struct cftype *cft, const char *buffer) | |
0dea1168 | 4026 | { |
182446d0 | 4027 | struct cgroup *cgrp = css->cgroup; |
876ede8b | 4028 | struct cgroup_event *event; |
f169007b | 4029 | struct cgroup *cgrp_cfile; |
0dea1168 | 4030 | unsigned int efd, cfd; |
876ede8b LZ |
4031 | struct file *efile; |
4032 | struct file *cfile; | |
0dea1168 KS |
4033 | char *endp; |
4034 | int ret; | |
4035 | ||
4036 | efd = simple_strtoul(buffer, &endp, 10); | |
4037 | if (*endp != ' ') | |
4038 | return -EINVAL; | |
4039 | buffer = endp + 1; | |
4040 | ||
4041 | cfd = simple_strtoul(buffer, &endp, 10); | |
4042 | if ((*endp != ' ') && (*endp != '\0')) | |
4043 | return -EINVAL; | |
4044 | buffer = endp + 1; | |
4045 | ||
4046 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
4047 | if (!event) | |
4048 | return -ENOMEM; | |
4049 | event->cgrp = cgrp; | |
4050 | INIT_LIST_HEAD(&event->list); | |
4051 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
4052 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
4053 | INIT_WORK(&event->remove, cgroup_event_remove); | |
4054 | ||
4055 | efile = eventfd_fget(efd); | |
4056 | if (IS_ERR(efile)) { | |
4057 | ret = PTR_ERR(efile); | |
876ede8b | 4058 | goto out_kfree; |
0dea1168 KS |
4059 | } |
4060 | ||
4061 | event->eventfd = eventfd_ctx_fileget(efile); | |
4062 | if (IS_ERR(event->eventfd)) { | |
4063 | ret = PTR_ERR(event->eventfd); | |
876ede8b | 4064 | goto out_put_efile; |
0dea1168 KS |
4065 | } |
4066 | ||
4067 | cfile = fget(cfd); | |
4068 | if (!cfile) { | |
4069 | ret = -EBADF; | |
876ede8b | 4070 | goto out_put_eventfd; |
0dea1168 KS |
4071 | } |
4072 | ||
4073 | /* the process need read permission on control file */ | |
3bfa784a | 4074 | /* AV: shouldn't we check that it's been opened for read instead? */ |
496ad9aa | 4075 | ret = inode_permission(file_inode(cfile), MAY_READ); |
0dea1168 | 4076 | if (ret < 0) |
876ede8b | 4077 | goto out_put_cfile; |
0dea1168 KS |
4078 | |
4079 | event->cft = __file_cft(cfile); | |
4080 | if (IS_ERR(event->cft)) { | |
4081 | ret = PTR_ERR(event->cft); | |
876ede8b | 4082 | goto out_put_cfile; |
0dea1168 KS |
4083 | } |
4084 | ||
f169007b LZ |
4085 | /* |
4086 | * The file to be monitored must be in the same cgroup as | |
4087 | * cgroup.event_control is. | |
4088 | */ | |
4089 | cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); | |
4090 | if (cgrp_cfile != cgrp) { | |
4091 | ret = -EINVAL; | |
876ede8b | 4092 | goto out_put_cfile; |
f169007b LZ |
4093 | } |
4094 | ||
0dea1168 KS |
4095 | if (!event->cft->register_event || !event->cft->unregister_event) { |
4096 | ret = -EINVAL; | |
876ede8b | 4097 | goto out_put_cfile; |
0dea1168 KS |
4098 | } |
4099 | ||
4100 | ret = event->cft->register_event(cgrp, event->cft, | |
4101 | event->eventfd, buffer); | |
4102 | if (ret) | |
876ede8b | 4103 | goto out_put_cfile; |
0dea1168 | 4104 | |
7ef70e48 | 4105 | efile->f_op->poll(efile, &event->pt); |
0dea1168 | 4106 | |
a0a4db54 KS |
4107 | /* |
4108 | * Events should be removed after rmdir of cgroup directory, but before | |
4109 | * destroying subsystem state objects. Let's take reference to cgroup | |
4110 | * directory dentry to do that. | |
4111 | */ | |
4112 | dget(cgrp->dentry); | |
4113 | ||
0dea1168 KS |
4114 | spin_lock(&cgrp->event_list_lock); |
4115 | list_add(&event->list, &cgrp->event_list); | |
4116 | spin_unlock(&cgrp->event_list_lock); | |
4117 | ||
4118 | fput(cfile); | |
4119 | fput(efile); | |
4120 | ||
4121 | return 0; | |
4122 | ||
876ede8b LZ |
4123 | out_put_cfile: |
4124 | fput(cfile); | |
4125 | out_put_eventfd: | |
4126 | eventfd_ctx_put(event->eventfd); | |
4127 | out_put_efile: | |
4128 | fput(efile); | |
4129 | out_kfree: | |
0dea1168 KS |
4130 | kfree(event); |
4131 | ||
4132 | return ret; | |
4133 | } | |
4134 | ||
182446d0 TH |
4135 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
4136 | struct cftype *cft) | |
97978e6d | 4137 | { |
182446d0 | 4138 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4139 | } |
4140 | ||
182446d0 TH |
4141 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
4142 | struct cftype *cft, u64 val) | |
97978e6d DL |
4143 | { |
4144 | if (val) | |
182446d0 | 4145 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 4146 | else |
182446d0 | 4147 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4148 | return 0; |
4149 | } | |
4150 | ||
d5c56ced | 4151 | static struct cftype cgroup_base_files[] = { |
81a6a5cd | 4152 | { |
d5c56ced | 4153 | .name = "cgroup.procs", |
102a775e | 4154 | .open = cgroup_procs_open, |
74a1166d | 4155 | .write_u64 = cgroup_procs_write, |
102a775e | 4156 | .release = cgroup_pidlist_release, |
74a1166d | 4157 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 4158 | }, |
81a6a5cd | 4159 | { |
d5c56ced | 4160 | .name = "cgroup.event_control", |
0dea1168 KS |
4161 | .write_string = cgroup_write_event_control, |
4162 | .mode = S_IWUGO, | |
4163 | }, | |
97978e6d DL |
4164 | { |
4165 | .name = "cgroup.clone_children", | |
873fe09e | 4166 | .flags = CFTYPE_INSANE, |
97978e6d DL |
4167 | .read_u64 = cgroup_clone_children_read, |
4168 | .write_u64 = cgroup_clone_children_write, | |
4169 | }, | |
873fe09e TH |
4170 | { |
4171 | .name = "cgroup.sane_behavior", | |
4172 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4173 | .read_seq_string = cgroup_sane_behavior_show, | |
4174 | }, | |
d5c56ced TH |
4175 | |
4176 | /* | |
4177 | * Historical crazy stuff. These don't have "cgroup." prefix and | |
4178 | * don't exist if sane_behavior. If you're depending on these, be | |
4179 | * prepared to be burned. | |
4180 | */ | |
4181 | { | |
4182 | .name = "tasks", | |
4183 | .flags = CFTYPE_INSANE, /* use "procs" instead */ | |
4184 | .open = cgroup_tasks_open, | |
4185 | .write_u64 = cgroup_tasks_write, | |
4186 | .release = cgroup_pidlist_release, | |
4187 | .mode = S_IRUGO | S_IWUSR, | |
4188 | }, | |
4189 | { | |
4190 | .name = "notify_on_release", | |
4191 | .flags = CFTYPE_INSANE, | |
4192 | .read_u64 = cgroup_read_notify_on_release, | |
4193 | .write_u64 = cgroup_write_notify_on_release, | |
4194 | }, | |
6e6ff25b TH |
4195 | { |
4196 | .name = "release_agent", | |
cc5943a7 | 4197 | .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT, |
6e6ff25b TH |
4198 | .read_seq_string = cgroup_release_agent_show, |
4199 | .write_string = cgroup_release_agent_write, | |
4200 | .max_write_len = PATH_MAX, | |
4201 | }, | |
db0416b6 | 4202 | { } /* terminate */ |
bbcb81d0 PM |
4203 | }; |
4204 | ||
13af07df | 4205 | /** |
628f7cd4 | 4206 | * cgroup_populate_dir - create subsys files in a cgroup directory |
13af07df | 4207 | * @cgrp: target cgroup |
13af07df | 4208 | * @subsys_mask: mask of the subsystem ids whose files should be added |
bee55099 TH |
4209 | * |
4210 | * On failure, no file is added. | |
13af07df | 4211 | */ |
628f7cd4 | 4212 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
ddbcc7e8 | 4213 | { |
ddbcc7e8 | 4214 | struct cgroup_subsys *ss; |
b420ba7d | 4215 | int i, ret = 0; |
ddbcc7e8 | 4216 | |
8e3f6541 | 4217 | /* process cftsets of each subsystem */ |
b420ba7d | 4218 | for_each_subsys(ss, i) { |
8e3f6541 | 4219 | struct cftype_set *set; |
b420ba7d TH |
4220 | |
4221 | if (!test_bit(i, &subsys_mask)) | |
13af07df | 4222 | continue; |
8e3f6541 | 4223 | |
bee55099 | 4224 | list_for_each_entry(set, &ss->cftsets, node) { |
2bb566cb | 4225 | ret = cgroup_addrm_files(cgrp, set->cfts, true); |
bee55099 TH |
4226 | if (ret < 0) |
4227 | goto err; | |
4228 | } | |
ddbcc7e8 | 4229 | } |
8e3f6541 | 4230 | |
38460b48 | 4231 | /* This cgroup is ready now */ |
5549c497 | 4232 | for_each_root_subsys(cgrp->root, ss) { |
38460b48 | 4233 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
a4ea1cc9 TH |
4234 | struct css_id *id = rcu_dereference_protected(css->id, true); |
4235 | ||
38460b48 KH |
4236 | /* |
4237 | * Update id->css pointer and make this css visible from | |
4238 | * CSS ID functions. This pointer will be dereferened | |
4239 | * from RCU-read-side without locks. | |
4240 | */ | |
a4ea1cc9 TH |
4241 | if (id) |
4242 | rcu_assign_pointer(id->css, css); | |
38460b48 | 4243 | } |
ddbcc7e8 PM |
4244 | |
4245 | return 0; | |
bee55099 TH |
4246 | err: |
4247 | cgroup_clear_dir(cgrp, subsys_mask); | |
4248 | return ret; | |
ddbcc7e8 PM |
4249 | } |
4250 | ||
48ddbe19 TH |
4251 | static void css_dput_fn(struct work_struct *work) |
4252 | { | |
4253 | struct cgroup_subsys_state *css = | |
4254 | container_of(work, struct cgroup_subsys_state, dput_work); | |
4255 | ||
1c8158ee | 4256 | cgroup_dput(css->cgroup); |
48ddbe19 TH |
4257 | } |
4258 | ||
d3daf28d TH |
4259 | static void css_release(struct percpu_ref *ref) |
4260 | { | |
4261 | struct cgroup_subsys_state *css = | |
4262 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4263 | ||
4264 | schedule_work(&css->dput_work); | |
4265 | } | |
4266 | ||
ddbcc7e8 PM |
4267 | static void init_cgroup_css(struct cgroup_subsys_state *css, |
4268 | struct cgroup_subsys *ss, | |
bd89aabc | 4269 | struct cgroup *cgrp) |
ddbcc7e8 | 4270 | { |
bd89aabc | 4271 | css->cgroup = cgrp; |
72c97e54 | 4272 | css->ss = ss; |
ddbcc7e8 | 4273 | css->flags = 0; |
38460b48 | 4274 | css->id = NULL; |
9871bf95 | 4275 | if (cgrp == cgroup_dummy_top) |
38b53aba | 4276 | css->flags |= CSS_ROOT; |
bd89aabc PM |
4277 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
4278 | cgrp->subsys[ss->subsys_id] = css; | |
48ddbe19 TH |
4279 | |
4280 | /* | |
ed957793 TH |
4281 | * css holds an extra ref to @cgrp->dentry which is put on the last |
4282 | * css_put(). dput() requires process context, which css_put() may | |
4283 | * be called without. @css->dput_work will be used to invoke | |
4284 | * dput() asynchronously from css_put(). | |
48ddbe19 TH |
4285 | */ |
4286 | INIT_WORK(&css->dput_work, css_dput_fn); | |
ddbcc7e8 PM |
4287 | } |
4288 | ||
2a4ac633 | 4289 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
b1929db4 | 4290 | static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) |
a31f2d3f | 4291 | { |
eb95419b | 4292 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
b1929db4 TH |
4293 | int ret = 0; |
4294 | ||
a31f2d3f TH |
4295 | lockdep_assert_held(&cgroup_mutex); |
4296 | ||
92fb9748 | 4297 | if (ss->css_online) |
eb95419b | 4298 | ret = ss->css_online(css); |
b1929db4 | 4299 | if (!ret) |
eb95419b | 4300 | css->flags |= CSS_ONLINE; |
b1929db4 | 4301 | return ret; |
a31f2d3f TH |
4302 | } |
4303 | ||
2a4ac633 | 4304 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
a31f2d3f | 4305 | static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) |
a31f2d3f TH |
4306 | { |
4307 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
4308 | ||
4309 | lockdep_assert_held(&cgroup_mutex); | |
4310 | ||
4311 | if (!(css->flags & CSS_ONLINE)) | |
4312 | return; | |
4313 | ||
d7eeac19 | 4314 | if (ss->css_offline) |
eb95419b | 4315 | ss->css_offline(css); |
a31f2d3f | 4316 | |
eb95419b | 4317 | css->flags &= ~CSS_ONLINE; |
a31f2d3f TH |
4318 | } |
4319 | ||
ddbcc7e8 | 4320 | /* |
a043e3b2 LZ |
4321 | * cgroup_create - create a cgroup |
4322 | * @parent: cgroup that will be parent of the new cgroup | |
4323 | * @dentry: dentry of the new cgroup | |
4324 | * @mode: mode to set on new inode | |
ddbcc7e8 | 4325 | * |
a043e3b2 | 4326 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 4327 | */ |
ddbcc7e8 | 4328 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
a5e7ed32 | 4329 | umode_t mode) |
ddbcc7e8 | 4330 | { |
bd89aabc | 4331 | struct cgroup *cgrp; |
65dff759 | 4332 | struct cgroup_name *name; |
ddbcc7e8 PM |
4333 | struct cgroupfs_root *root = parent->root; |
4334 | int err = 0; | |
4335 | struct cgroup_subsys *ss; | |
4336 | struct super_block *sb = root->sb; | |
4337 | ||
0a950f65 | 4338 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc PM |
4339 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
4340 | if (!cgrp) | |
ddbcc7e8 PM |
4341 | return -ENOMEM; |
4342 | ||
65dff759 LZ |
4343 | name = cgroup_alloc_name(dentry); |
4344 | if (!name) | |
4345 | goto err_free_cgrp; | |
4346 | rcu_assign_pointer(cgrp->name, name); | |
4347 | ||
4e96ee8e LZ |
4348 | /* |
4349 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
4350 | * a half-baked cgroup. | |
4351 | */ | |
4352 | cgrp->id = idr_alloc(&root->cgroup_idr, NULL, 1, 0, GFP_KERNEL); | |
0a950f65 | 4353 | if (cgrp->id < 0) |
65dff759 | 4354 | goto err_free_name; |
0a950f65 | 4355 | |
976c06bc TH |
4356 | /* |
4357 | * Only live parents can have children. Note that the liveliness | |
4358 | * check isn't strictly necessary because cgroup_mkdir() and | |
4359 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
4360 | * anyway so that locking is contained inside cgroup proper and we | |
4361 | * don't get nasty surprises if we ever grow another caller. | |
4362 | */ | |
4363 | if (!cgroup_lock_live_group(parent)) { | |
4364 | err = -ENODEV; | |
0a950f65 | 4365 | goto err_free_id; |
976c06bc TH |
4366 | } |
4367 | ||
ddbcc7e8 PM |
4368 | /* Grab a reference on the superblock so the hierarchy doesn't |
4369 | * get deleted on unmount if there are child cgroups. This | |
4370 | * can be done outside cgroup_mutex, since the sb can't | |
4371 | * disappear while someone has an open control file on the | |
4372 | * fs */ | |
4373 | atomic_inc(&sb->s_active); | |
4374 | ||
cc31edce | 4375 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4376 | |
fe1c06ca LZ |
4377 | dentry->d_fsdata = cgrp; |
4378 | cgrp->dentry = dentry; | |
4379 | ||
bd89aabc PM |
4380 | cgrp->parent = parent; |
4381 | cgrp->root = parent->root; | |
ddbcc7e8 | 4382 | |
b6abdb0e LZ |
4383 | if (notify_on_release(parent)) |
4384 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4385 | ||
2260e7fc TH |
4386 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4387 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4388 | |
5549c497 | 4389 | for_each_root_subsys(root, ss) { |
8c7f6edb | 4390 | struct cgroup_subsys_state *css; |
4528fd05 | 4391 | |
eb95419b | 4392 | css = ss->css_alloc(parent->subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4393 | if (IS_ERR(css)) { |
4394 | err = PTR_ERR(css); | |
4b8b47eb | 4395 | goto err_free_all; |
ddbcc7e8 | 4396 | } |
d3daf28d TH |
4397 | |
4398 | err = percpu_ref_init(&css->refcnt, css_release); | |
da0a12ca | 4399 | if (err) { |
eb95419b | 4400 | ss->css_free(css); |
d3daf28d | 4401 | goto err_free_all; |
da0a12ca | 4402 | } |
d3daf28d | 4403 | |
bd89aabc | 4404 | init_cgroup_css(css, ss, cgrp); |
d3daf28d | 4405 | |
4528fd05 LZ |
4406 | if (ss->use_id) { |
4407 | err = alloc_css_id(ss, parent, cgrp); | |
4408 | if (err) | |
4b8b47eb | 4409 | goto err_free_all; |
4528fd05 | 4410 | } |
ddbcc7e8 PM |
4411 | } |
4412 | ||
4e139afc TH |
4413 | /* |
4414 | * Create directory. cgroup_create_file() returns with the new | |
4415 | * directory locked on success so that it can be populated without | |
4416 | * dropping cgroup_mutex. | |
4417 | */ | |
28fd6f30 | 4418 | err = cgroup_create_file(dentry, S_IFDIR | mode, sb); |
ddbcc7e8 | 4419 | if (err < 0) |
4b8b47eb | 4420 | goto err_free_all; |
4e139afc | 4421 | lockdep_assert_held(&dentry->d_inode->i_mutex); |
ddbcc7e8 | 4422 | |
00356bd5 | 4423 | cgrp->serial_nr = cgroup_serial_nr_next++; |
53fa5261 | 4424 | |
4e139afc | 4425 | /* allocation complete, commit to creation */ |
4e139afc TH |
4426 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); |
4427 | root->number_of_cgroups++; | |
28fd6f30 | 4428 | |
b1929db4 | 4429 | /* each css holds a ref to the cgroup's dentry */ |
5549c497 | 4430 | for_each_root_subsys(root, ss) |
ed957793 | 4431 | dget(dentry); |
48ddbe19 | 4432 | |
415cf07a LZ |
4433 | /* hold a ref to the parent's dentry */ |
4434 | dget(parent->dentry); | |
4435 | ||
b1929db4 | 4436 | /* creation succeeded, notify subsystems */ |
5549c497 | 4437 | for_each_root_subsys(root, ss) { |
b1929db4 TH |
4438 | err = online_css(ss, cgrp); |
4439 | if (err) | |
4440 | goto err_destroy; | |
1f869e87 GC |
4441 | |
4442 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && | |
4443 | parent->parent) { | |
4444 | 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", | |
4445 | current->comm, current->pid, ss->name); | |
4446 | if (!strcmp(ss->name, "memory")) | |
4447 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
4448 | ss->warned_broken_hierarchy = true; | |
4449 | } | |
a8638030 TH |
4450 | } |
4451 | ||
4e96ee8e LZ |
4452 | idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
4453 | ||
2bb566cb | 4454 | err = cgroup_addrm_files(cgrp, cgroup_base_files, true); |
628f7cd4 TH |
4455 | if (err) |
4456 | goto err_destroy; | |
4457 | ||
4458 | err = cgroup_populate_dir(cgrp, root->subsys_mask); | |
4b8b47eb TH |
4459 | if (err) |
4460 | goto err_destroy; | |
ddbcc7e8 PM |
4461 | |
4462 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 4463 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
4464 | |
4465 | return 0; | |
4466 | ||
4b8b47eb | 4467 | err_free_all: |
5549c497 | 4468 | for_each_root_subsys(root, ss) { |
d3daf28d TH |
4469 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
4470 | ||
4471 | if (css) { | |
4472 | percpu_ref_cancel_init(&css->refcnt); | |
eb95419b | 4473 | ss->css_free(css); |
d3daf28d | 4474 | } |
ddbcc7e8 | 4475 | } |
ddbcc7e8 | 4476 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4477 | /* Release the reference count that we took on the superblock */ |
4478 | deactivate_super(sb); | |
0a950f65 | 4479 | err_free_id: |
4e96ee8e | 4480 | idr_remove(&root->cgroup_idr, cgrp->id); |
65dff759 LZ |
4481 | err_free_name: |
4482 | kfree(rcu_dereference_raw(cgrp->name)); | |
4b8b47eb | 4483 | err_free_cgrp: |
bd89aabc | 4484 | kfree(cgrp); |
ddbcc7e8 | 4485 | return err; |
4b8b47eb TH |
4486 | |
4487 | err_destroy: | |
4488 | cgroup_destroy_locked(cgrp); | |
4489 | mutex_unlock(&cgroup_mutex); | |
4490 | mutex_unlock(&dentry->d_inode->i_mutex); | |
4491 | return err; | |
ddbcc7e8 PM |
4492 | } |
4493 | ||
18bb1db3 | 4494 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
ddbcc7e8 PM |
4495 | { |
4496 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
4497 | ||
4498 | /* the vfs holds inode->i_mutex already */ | |
4499 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
4500 | } | |
4501 | ||
d3daf28d TH |
4502 | static void cgroup_css_killed(struct cgroup *cgrp) |
4503 | { | |
4504 | if (!atomic_dec_and_test(&cgrp->css_kill_cnt)) | |
4505 | return; | |
4506 | ||
4507 | /* percpu ref's of all css's are killed, kick off the next step */ | |
4508 | INIT_WORK(&cgrp->destroy_work, cgroup_offline_fn); | |
4509 | schedule_work(&cgrp->destroy_work); | |
4510 | } | |
4511 | ||
4512 | static void css_ref_killed_fn(struct percpu_ref *ref) | |
4513 | { | |
4514 | struct cgroup_subsys_state *css = | |
4515 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4516 | ||
4517 | cgroup_css_killed(css->cgroup); | |
4518 | } | |
4519 | ||
4520 | /** | |
4521 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
4522 | * @cgrp: cgroup to be destroyed | |
4523 | * | |
4524 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
4525 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
4526 | * guarantee that css_tryget() won't succeed by the time ->css_offline() is | |
4527 | * invoked. To satisfy all the requirements, destruction is implemented in | |
4528 | * the following two steps. | |
4529 | * | |
4530 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
4531 | * userland visible parts and start killing the percpu refcnts of | |
4532 | * css's. Set up so that the next stage will be kicked off once all | |
4533 | * the percpu refcnts are confirmed to be killed. | |
4534 | * | |
4535 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
4536 | * rest of destruction. Once all cgroup references are gone, the | |
4537 | * cgroup is RCU-freed. | |
4538 | * | |
4539 | * This function implements s1. After this step, @cgrp is gone as far as | |
4540 | * the userland is concerned and a new cgroup with the same name may be | |
4541 | * created. As cgroup doesn't care about the names internally, this | |
4542 | * doesn't cause any problem. | |
4543 | */ | |
42809dd4 TH |
4544 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4545 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4546 | { |
42809dd4 | 4547 | struct dentry *d = cgrp->dentry; |
4ab78683 | 4548 | struct cgroup_event *event, *tmp; |
ed957793 | 4549 | struct cgroup_subsys *ss; |
ddd69148 | 4550 | bool empty; |
ddbcc7e8 | 4551 | |
42809dd4 TH |
4552 | lockdep_assert_held(&d->d_inode->i_mutex); |
4553 | lockdep_assert_held(&cgroup_mutex); | |
4554 | ||
ddd69148 | 4555 | /* |
6f3d828f TH |
4556 | * css_set_lock synchronizes access to ->cset_links and prevents |
4557 | * @cgrp from being removed while __put_css_set() is in progress. | |
ddd69148 TH |
4558 | */ |
4559 | read_lock(&css_set_lock); | |
6f3d828f | 4560 | empty = list_empty(&cgrp->cset_links) && list_empty(&cgrp->children); |
ddd69148 TH |
4561 | read_unlock(&css_set_lock); |
4562 | if (!empty) | |
ddbcc7e8 | 4563 | return -EBUSY; |
a043e3b2 | 4564 | |
88703267 | 4565 | /* |
d3daf28d TH |
4566 | * Block new css_tryget() by killing css refcnts. cgroup core |
4567 | * guarantees that, by the time ->css_offline() is invoked, no new | |
4568 | * css reference will be given out via css_tryget(). We can't | |
4569 | * simply call percpu_ref_kill() and proceed to offlining css's | |
4570 | * because percpu_ref_kill() doesn't guarantee that the ref is seen | |
4571 | * as killed on all CPUs on return. | |
4572 | * | |
4573 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
4574 | * css is confirmed to be seen as killed on all CPUs. The | |
4575 | * notification callback keeps track of the number of css's to be | |
4576 | * killed and schedules cgroup_offline_fn() to perform the rest of | |
4577 | * destruction once the percpu refs of all css's are confirmed to | |
4578 | * be killed. | |
88703267 | 4579 | */ |
d3daf28d | 4580 | atomic_set(&cgrp->css_kill_cnt, 1); |
5549c497 | 4581 | for_each_root_subsys(cgrp->root, ss) { |
ed957793 | 4582 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; |
88703267 | 4583 | |
d3daf28d TH |
4584 | /* |
4585 | * Killing would put the base ref, but we need to keep it | |
4586 | * alive until after ->css_offline. | |
4587 | */ | |
4588 | percpu_ref_get(&css->refcnt); | |
4589 | ||
4590 | atomic_inc(&cgrp->css_kill_cnt); | |
4591 | percpu_ref_kill_and_confirm(&css->refcnt, css_ref_killed_fn); | |
88703267 | 4592 | } |
d3daf28d | 4593 | cgroup_css_killed(cgrp); |
455050d2 TH |
4594 | |
4595 | /* | |
4596 | * Mark @cgrp dead. This prevents further task migration and child | |
4597 | * creation by disabling cgroup_lock_live_group(). Note that | |
492eb21b | 4598 | * CGRP_DEAD assertion is depended upon by css_next_child() to |
455050d2 | 4599 | * resume iteration after dropping RCU read lock. See |
492eb21b | 4600 | * css_next_child() for details. |
455050d2 | 4601 | */ |
54766d4a | 4602 | set_bit(CGRP_DEAD, &cgrp->flags); |
ddbcc7e8 | 4603 | |
455050d2 TH |
4604 | /* CGRP_DEAD is set, remove from ->release_list for the last time */ |
4605 | raw_spin_lock(&release_list_lock); | |
4606 | if (!list_empty(&cgrp->release_list)) | |
4607 | list_del_init(&cgrp->release_list); | |
4608 | raw_spin_unlock(&release_list_lock); | |
4609 | ||
4610 | /* | |
8f89140a TH |
4611 | * Clear and remove @cgrp directory. The removal puts the base ref |
4612 | * but we aren't quite done with @cgrp yet, so hold onto it. | |
455050d2 | 4613 | */ |
628f7cd4 | 4614 | cgroup_clear_dir(cgrp, cgrp->root->subsys_mask); |
2bb566cb | 4615 | cgroup_addrm_files(cgrp, cgroup_base_files, false); |
455050d2 TH |
4616 | dget(d); |
4617 | cgroup_d_remove_dir(d); | |
4618 | ||
4619 | /* | |
4620 | * Unregister events and notify userspace. | |
4621 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
4622 | * directory to avoid race between userspace and kernelspace. | |
4623 | */ | |
4624 | spin_lock(&cgrp->event_list_lock); | |
4625 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { | |
4626 | list_del_init(&event->list); | |
4627 | schedule_work(&event->remove); | |
4628 | } | |
4629 | spin_unlock(&cgrp->event_list_lock); | |
4630 | ||
ea15f8cc TH |
4631 | return 0; |
4632 | }; | |
4633 | ||
d3daf28d TH |
4634 | /** |
4635 | * cgroup_offline_fn - the second step of cgroup destruction | |
4636 | * @work: cgroup->destroy_free_work | |
4637 | * | |
4638 | * This function is invoked from a work item for a cgroup which is being | |
4639 | * destroyed after the percpu refcnts of all css's are guaranteed to be | |
4640 | * seen as killed on all CPUs, and performs the rest of destruction. This | |
4641 | * is the second step of destruction described in the comment above | |
4642 | * cgroup_destroy_locked(). | |
4643 | */ | |
ea15f8cc TH |
4644 | static void cgroup_offline_fn(struct work_struct *work) |
4645 | { | |
4646 | struct cgroup *cgrp = container_of(work, struct cgroup, destroy_work); | |
4647 | struct cgroup *parent = cgrp->parent; | |
4648 | struct dentry *d = cgrp->dentry; | |
4649 | struct cgroup_subsys *ss; | |
4650 | ||
4651 | mutex_lock(&cgroup_mutex); | |
4652 | ||
d3daf28d TH |
4653 | /* |
4654 | * css_tryget() is guaranteed to fail now. Tell subsystems to | |
4655 | * initate destruction. | |
4656 | */ | |
5549c497 | 4657 | for_each_root_subsys(cgrp->root, ss) |
a31f2d3f | 4658 | offline_css(ss, cgrp); |
ed957793 TH |
4659 | |
4660 | /* | |
d3daf28d TH |
4661 | * Put the css refs from cgroup_destroy_locked(). Each css holds |
4662 | * an extra reference to the cgroup's dentry and cgroup removal | |
4663 | * proceeds regardless of css refs. On the last put of each css, | |
4664 | * whenever that may be, the extra dentry ref is put so that dentry | |
4665 | * destruction happens only after all css's are released. | |
ed957793 | 4666 | */ |
5549c497 | 4667 | for_each_root_subsys(cgrp->root, ss) |
e9316080 | 4668 | css_put(cgrp->subsys[ss->subsys_id]); |
ddbcc7e8 | 4669 | |
999cd8a4 | 4670 | /* delete this cgroup from parent->children */ |
eb6fd504 | 4671 | list_del_rcu(&cgrp->sibling); |
b0ca5a84 | 4672 | |
4e96ee8e LZ |
4673 | /* |
4674 | * We should remove the cgroup object from idr before its grace | |
4675 | * period starts, so we won't be looking up a cgroup while the | |
4676 | * cgroup is being freed. | |
4677 | */ | |
4678 | idr_remove(&cgrp->root->cgroup_idr, cgrp->id); | |
4679 | cgrp->id = -1; | |
4680 | ||
ddbcc7e8 | 4681 | dput(d); |
ddbcc7e8 | 4682 | |
bd89aabc | 4683 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
4684 | check_for_release(parent); |
4685 | ||
ea15f8cc | 4686 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4687 | } |
4688 | ||
42809dd4 TH |
4689 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
4690 | { | |
4691 | int ret; | |
4692 | ||
4693 | mutex_lock(&cgroup_mutex); | |
4694 | ret = cgroup_destroy_locked(dentry->d_fsdata); | |
4695 | mutex_unlock(&cgroup_mutex); | |
4696 | ||
4697 | return ret; | |
4698 | } | |
4699 | ||
8e3f6541 TH |
4700 | static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) |
4701 | { | |
4702 | INIT_LIST_HEAD(&ss->cftsets); | |
4703 | ||
4704 | /* | |
4705 | * base_cftset is embedded in subsys itself, no need to worry about | |
4706 | * deregistration. | |
4707 | */ | |
4708 | if (ss->base_cftypes) { | |
2bb566cb TH |
4709 | struct cftype *cft; |
4710 | ||
4711 | for (cft = ss->base_cftypes; cft->name[0] != '\0'; cft++) | |
4712 | cft->ss = ss; | |
4713 | ||
8e3f6541 TH |
4714 | ss->base_cftset.cfts = ss->base_cftypes; |
4715 | list_add_tail(&ss->base_cftset.node, &ss->cftsets); | |
4716 | } | |
4717 | } | |
4718 | ||
06a11920 | 4719 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4720 | { |
ddbcc7e8 | 4721 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4722 | |
4723 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 4724 | |
648bb56d TH |
4725 | mutex_lock(&cgroup_mutex); |
4726 | ||
8e3f6541 TH |
4727 | /* init base cftset */ |
4728 | cgroup_init_cftsets(ss); | |
4729 | ||
ddbcc7e8 | 4730 | /* Create the top cgroup state for this subsystem */ |
9871bf95 TH |
4731 | list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); |
4732 | ss->root = &cgroup_dummy_root; | |
eb95419b | 4733 | css = ss->css_alloc(cgroup_dummy_top->subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4734 | /* We don't handle early failures gracefully */ |
4735 | BUG_ON(IS_ERR(css)); | |
9871bf95 | 4736 | init_cgroup_css(css, ss, cgroup_dummy_top); |
ddbcc7e8 | 4737 | |
e8d55fde | 4738 | /* Update the init_css_set to contain a subsys |
817929ec | 4739 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
4740 | * newly registered, all tasks and hence the |
4741 | * init_css_set is in the subsystem's top cgroup. */ | |
b48c6a80 | 4742 | init_css_set.subsys[ss->subsys_id] = css; |
ddbcc7e8 PM |
4743 | |
4744 | need_forkexit_callback |= ss->fork || ss->exit; | |
4745 | ||
e8d55fde LZ |
4746 | /* At system boot, before all subsystems have been |
4747 | * registered, no tasks have been forked, so we don't | |
4748 | * need to invoke fork callbacks here. */ | |
4749 | BUG_ON(!list_empty(&init_task.tasks)); | |
4750 | ||
9871bf95 | 4751 | BUG_ON(online_css(ss, cgroup_dummy_top)); |
a8638030 | 4752 | |
648bb56d TH |
4753 | mutex_unlock(&cgroup_mutex); |
4754 | ||
e6a1105b BB |
4755 | /* this function shouldn't be used with modular subsystems, since they |
4756 | * need to register a subsys_id, among other things */ | |
4757 | BUG_ON(ss->module); | |
4758 | } | |
4759 | ||
4760 | /** | |
4761 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
4762 | * @ss: the subsystem to load | |
4763 | * | |
4764 | * This function should be called in a modular subsystem's initcall. If the | |
88393161 | 4765 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
e6a1105b BB |
4766 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
4767 | * simpler cgroup_init_subsys. | |
4768 | */ | |
4769 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
4770 | { | |
e6a1105b | 4771 | struct cgroup_subsys_state *css; |
d19e19de | 4772 | int i, ret; |
b67bfe0d | 4773 | struct hlist_node *tmp; |
5abb8855 | 4774 | struct css_set *cset; |
0ac801fe | 4775 | unsigned long key; |
e6a1105b BB |
4776 | |
4777 | /* check name and function validity */ | |
4778 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
92fb9748 | 4779 | ss->css_alloc == NULL || ss->css_free == NULL) |
e6a1105b BB |
4780 | return -EINVAL; |
4781 | ||
4782 | /* | |
4783 | * we don't support callbacks in modular subsystems. this check is | |
4784 | * before the ss->module check for consistency; a subsystem that could | |
4785 | * be a module should still have no callbacks even if the user isn't | |
4786 | * compiling it as one. | |
4787 | */ | |
4788 | if (ss->fork || ss->exit) | |
4789 | return -EINVAL; | |
4790 | ||
4791 | /* | |
4792 | * an optionally modular subsystem is built-in: we want to do nothing, | |
4793 | * since cgroup_init_subsys will have already taken care of it. | |
4794 | */ | |
4795 | if (ss->module == NULL) { | |
be45c900 | 4796 | /* a sanity check */ |
9871bf95 | 4797 | BUG_ON(cgroup_subsys[ss->subsys_id] != ss); |
e6a1105b BB |
4798 | return 0; |
4799 | } | |
4800 | ||
8e3f6541 TH |
4801 | /* init base cftset */ |
4802 | cgroup_init_cftsets(ss); | |
4803 | ||
e6a1105b | 4804 | mutex_lock(&cgroup_mutex); |
9871bf95 | 4805 | cgroup_subsys[ss->subsys_id] = ss; |
e6a1105b BB |
4806 | |
4807 | /* | |
92fb9748 | 4808 | * no ss->css_alloc seems to need anything important in the ss |
9871bf95 | 4809 | * struct, so this can happen first (i.e. before the dummy root |
92fb9748 | 4810 | * attachment). |
e6a1105b | 4811 | */ |
eb95419b | 4812 | css = ss->css_alloc(cgroup_dummy_top->subsys[ss->subsys_id]); |
e6a1105b | 4813 | if (IS_ERR(css)) { |
9871bf95 TH |
4814 | /* failure case - need to deassign the cgroup_subsys[] slot. */ |
4815 | cgroup_subsys[ss->subsys_id] = NULL; | |
e6a1105b BB |
4816 | mutex_unlock(&cgroup_mutex); |
4817 | return PTR_ERR(css); | |
4818 | } | |
4819 | ||
9871bf95 TH |
4820 | list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); |
4821 | ss->root = &cgroup_dummy_root; | |
e6a1105b BB |
4822 | |
4823 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
9871bf95 | 4824 | init_cgroup_css(css, ss, cgroup_dummy_top); |
e6a1105b BB |
4825 | /* init_idr must be after init_cgroup_css because it sets css->id. */ |
4826 | if (ss->use_id) { | |
d19e19de TH |
4827 | ret = cgroup_init_idr(ss, css); |
4828 | if (ret) | |
4829 | goto err_unload; | |
e6a1105b BB |
4830 | } |
4831 | ||
4832 | /* | |
4833 | * Now we need to entangle the css into the existing css_sets. unlike | |
4834 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
4835 | * will need a new pointer to it; done by iterating the css_set_table. | |
4836 | * furthermore, modifying the existing css_sets will corrupt the hash | |
4837 | * table state, so each changed css_set will need its hash recomputed. | |
4838 | * this is all done under the css_set_lock. | |
4839 | */ | |
4840 | write_lock(&css_set_lock); | |
5abb8855 | 4841 | hash_for_each_safe(css_set_table, i, tmp, cset, hlist) { |
0ac801fe | 4842 | /* skip entries that we already rehashed */ |
5abb8855 | 4843 | if (cset->subsys[ss->subsys_id]) |
0ac801fe LZ |
4844 | continue; |
4845 | /* remove existing entry */ | |
5abb8855 | 4846 | hash_del(&cset->hlist); |
0ac801fe | 4847 | /* set new value */ |
5abb8855 | 4848 | cset->subsys[ss->subsys_id] = css; |
0ac801fe | 4849 | /* recompute hash and restore entry */ |
5abb8855 TH |
4850 | key = css_set_hash(cset->subsys); |
4851 | hash_add(css_set_table, &cset->hlist, key); | |
e6a1105b BB |
4852 | } |
4853 | write_unlock(&css_set_lock); | |
4854 | ||
9871bf95 | 4855 | ret = online_css(ss, cgroup_dummy_top); |
b1929db4 TH |
4856 | if (ret) |
4857 | goto err_unload; | |
a8638030 | 4858 | |
e6a1105b BB |
4859 | /* success! */ |
4860 | mutex_unlock(&cgroup_mutex); | |
4861 | return 0; | |
d19e19de TH |
4862 | |
4863 | err_unload: | |
4864 | mutex_unlock(&cgroup_mutex); | |
4865 | /* @ss can't be mounted here as try_module_get() would fail */ | |
4866 | cgroup_unload_subsys(ss); | |
4867 | return ret; | |
ddbcc7e8 | 4868 | } |
e6a1105b | 4869 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
ddbcc7e8 | 4870 | |
cf5d5941 BB |
4871 | /** |
4872 | * cgroup_unload_subsys: unload a modular subsystem | |
4873 | * @ss: the subsystem to unload | |
4874 | * | |
4875 | * This function should be called in a modular subsystem's exitcall. When this | |
4876 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
4877 | * the subsystem will not be attached to any hierarchy. | |
4878 | */ | |
4879 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
4880 | { | |
69d0206c | 4881 | struct cgrp_cset_link *link; |
cf5d5941 BB |
4882 | |
4883 | BUG_ON(ss->module == NULL); | |
4884 | ||
4885 | /* | |
4886 | * we shouldn't be called if the subsystem is in use, and the use of | |
1d5be6b2 | 4887 | * try_module_get() in rebind_subsystems() should ensure that it |
cf5d5941 BB |
4888 | * doesn't start being used while we're killing it off. |
4889 | */ | |
9871bf95 | 4890 | BUG_ON(ss->root != &cgroup_dummy_root); |
cf5d5941 BB |
4891 | |
4892 | mutex_lock(&cgroup_mutex); | |
02ae7486 | 4893 | |
9871bf95 | 4894 | offline_css(ss, cgroup_dummy_top); |
02ae7486 | 4895 | |
c897ff68 | 4896 | if (ss->use_id) |
02ae7486 | 4897 | idr_destroy(&ss->idr); |
02ae7486 | 4898 | |
cf5d5941 | 4899 | /* deassign the subsys_id */ |
9871bf95 | 4900 | cgroup_subsys[ss->subsys_id] = NULL; |
cf5d5941 | 4901 | |
9871bf95 | 4902 | /* remove subsystem from the dummy root's list of subsystems */ |
8d258797 | 4903 | list_del_init(&ss->sibling); |
cf5d5941 BB |
4904 | |
4905 | /* | |
9871bf95 TH |
4906 | * disentangle the css from all css_sets attached to the dummy |
4907 | * top. as in loading, we need to pay our respects to the hashtable | |
4908 | * gods. | |
cf5d5941 BB |
4909 | */ |
4910 | write_lock(&css_set_lock); | |
9871bf95 | 4911 | list_for_each_entry(link, &cgroup_dummy_top->cset_links, cset_link) { |
69d0206c | 4912 | struct css_set *cset = link->cset; |
0ac801fe | 4913 | unsigned long key; |
cf5d5941 | 4914 | |
5abb8855 TH |
4915 | hash_del(&cset->hlist); |
4916 | cset->subsys[ss->subsys_id] = NULL; | |
4917 | key = css_set_hash(cset->subsys); | |
4918 | hash_add(css_set_table, &cset->hlist, key); | |
cf5d5941 BB |
4919 | } |
4920 | write_unlock(&css_set_lock); | |
4921 | ||
4922 | /* | |
9871bf95 TH |
4923 | * remove subsystem's css from the cgroup_dummy_top and free it - |
4924 | * need to free before marking as null because ss->css_free needs | |
4925 | * the cgrp->subsys pointer to find their state. note that this | |
4926 | * also takes care of freeing the css_id. | |
cf5d5941 | 4927 | */ |
eb95419b | 4928 | ss->css_free(cgroup_dummy_top->subsys[ss->subsys_id]); |
9871bf95 | 4929 | cgroup_dummy_top->subsys[ss->subsys_id] = NULL; |
cf5d5941 BB |
4930 | |
4931 | mutex_unlock(&cgroup_mutex); | |
4932 | } | |
4933 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
4934 | ||
ddbcc7e8 | 4935 | /** |
a043e3b2 LZ |
4936 | * cgroup_init_early - cgroup initialization at system boot |
4937 | * | |
4938 | * Initialize cgroups at system boot, and initialize any | |
4939 | * subsystems that request early init. | |
ddbcc7e8 PM |
4940 | */ |
4941 | int __init cgroup_init_early(void) | |
4942 | { | |
30159ec7 | 4943 | struct cgroup_subsys *ss; |
ddbcc7e8 | 4944 | int i; |
30159ec7 | 4945 | |
146aa1bd | 4946 | atomic_set(&init_css_set.refcount, 1); |
69d0206c | 4947 | INIT_LIST_HEAD(&init_css_set.cgrp_links); |
817929ec | 4948 | INIT_LIST_HEAD(&init_css_set.tasks); |
472b1053 | 4949 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 4950 | css_set_count = 1; |
9871bf95 TH |
4951 | init_cgroup_root(&cgroup_dummy_root); |
4952 | cgroup_root_count = 1; | |
a4ea1cc9 | 4953 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 4954 | |
69d0206c | 4955 | init_cgrp_cset_link.cset = &init_css_set; |
9871bf95 TH |
4956 | init_cgrp_cset_link.cgrp = cgroup_dummy_top; |
4957 | list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links); | |
69d0206c | 4958 | list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links); |
ddbcc7e8 | 4959 | |
30159ec7 TH |
4960 | /* at bootup time, we don't worry about modular subsystems */ |
4961 | for_each_builtin_subsys(ss, i) { | |
ddbcc7e8 PM |
4962 | BUG_ON(!ss->name); |
4963 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
92fb9748 TH |
4964 | BUG_ON(!ss->css_alloc); |
4965 | BUG_ON(!ss->css_free); | |
ddbcc7e8 | 4966 | if (ss->subsys_id != i) { |
cfe36bde | 4967 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
4968 | ss->name, ss->subsys_id); |
4969 | BUG(); | |
4970 | } | |
4971 | ||
4972 | if (ss->early_init) | |
4973 | cgroup_init_subsys(ss); | |
4974 | } | |
4975 | return 0; | |
4976 | } | |
4977 | ||
4978 | /** | |
a043e3b2 LZ |
4979 | * cgroup_init - cgroup initialization |
4980 | * | |
4981 | * Register cgroup filesystem and /proc file, and initialize | |
4982 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4983 | */ |
4984 | int __init cgroup_init(void) | |
4985 | { | |
30159ec7 | 4986 | struct cgroup_subsys *ss; |
0ac801fe | 4987 | unsigned long key; |
30159ec7 | 4988 | int i, err; |
a424316c PM |
4989 | |
4990 | err = bdi_init(&cgroup_backing_dev_info); | |
4991 | if (err) | |
4992 | return err; | |
ddbcc7e8 | 4993 | |
30159ec7 | 4994 | for_each_builtin_subsys(ss, i) { |
ddbcc7e8 PM |
4995 | if (!ss->early_init) |
4996 | cgroup_init_subsys(ss); | |
38460b48 | 4997 | if (ss->use_id) |
e6a1105b | 4998 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4999 | } |
5000 | ||
fa3ca07e | 5001 | /* allocate id for the dummy hierarchy */ |
54e7b4eb TH |
5002 | mutex_lock(&cgroup_mutex); |
5003 | mutex_lock(&cgroup_root_mutex); | |
5004 | ||
82fe9b0d TH |
5005 | /* Add init_css_set to the hash table */ |
5006 | key = css_set_hash(init_css_set.subsys); | |
5007 | hash_add(css_set_table, &init_css_set.hlist, key); | |
5008 | ||
fc76df70 | 5009 | BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1)); |
676db4af | 5010 | |
4e96ee8e LZ |
5011 | err = idr_alloc(&cgroup_dummy_root.cgroup_idr, cgroup_dummy_top, |
5012 | 0, 1, GFP_KERNEL); | |
5013 | BUG_ON(err < 0); | |
5014 | ||
54e7b4eb TH |
5015 | mutex_unlock(&cgroup_root_mutex); |
5016 | mutex_unlock(&cgroup_mutex); | |
5017 | ||
676db4af GK |
5018 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
5019 | if (!cgroup_kobj) { | |
5020 | err = -ENOMEM; | |
5021 | goto out; | |
5022 | } | |
5023 | ||
ddbcc7e8 | 5024 | err = register_filesystem(&cgroup_fs_type); |
676db4af GK |
5025 | if (err < 0) { |
5026 | kobject_put(cgroup_kobj); | |
ddbcc7e8 | 5027 | goto out; |
676db4af | 5028 | } |
ddbcc7e8 | 5029 | |
46ae220b | 5030 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 5031 | |
ddbcc7e8 | 5032 | out: |
a424316c PM |
5033 | if (err) |
5034 | bdi_destroy(&cgroup_backing_dev_info); | |
5035 | ||
ddbcc7e8 PM |
5036 | return err; |
5037 | } | |
b4f48b63 | 5038 | |
a424316c PM |
5039 | /* |
5040 | * proc_cgroup_show() | |
5041 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
5042 | * - Used for /proc/<pid>/cgroup. | |
5043 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
5044 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 5045 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
5046 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
5047 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
5048 | * cgroup to top_cgroup. | |
5049 | */ | |
5050 | ||
5051 | /* TODO: Use a proper seq_file iterator */ | |
8d8b97ba | 5052 | int proc_cgroup_show(struct seq_file *m, void *v) |
a424316c PM |
5053 | { |
5054 | struct pid *pid; | |
5055 | struct task_struct *tsk; | |
5056 | char *buf; | |
5057 | int retval; | |
5058 | struct cgroupfs_root *root; | |
5059 | ||
5060 | retval = -ENOMEM; | |
5061 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
5062 | if (!buf) | |
5063 | goto out; | |
5064 | ||
5065 | retval = -ESRCH; | |
5066 | pid = m->private; | |
5067 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
5068 | if (!tsk) | |
5069 | goto out_free; | |
5070 | ||
5071 | retval = 0; | |
5072 | ||
5073 | mutex_lock(&cgroup_mutex); | |
5074 | ||
e5f6a860 | 5075 | for_each_active_root(root) { |
a424316c | 5076 | struct cgroup_subsys *ss; |
bd89aabc | 5077 | struct cgroup *cgrp; |
a424316c PM |
5078 | int count = 0; |
5079 | ||
2c6ab6d2 | 5080 | seq_printf(m, "%d:", root->hierarchy_id); |
5549c497 | 5081 | for_each_root_subsys(root, ss) |
a424316c | 5082 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); |
c6d57f33 PM |
5083 | if (strlen(root->name)) |
5084 | seq_printf(m, "%sname=%s", count ? "," : "", | |
5085 | root->name); | |
a424316c | 5086 | seq_putc(m, ':'); |
7717f7ba | 5087 | cgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 5088 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
a424316c PM |
5089 | if (retval < 0) |
5090 | goto out_unlock; | |
5091 | seq_puts(m, buf); | |
5092 | seq_putc(m, '\n'); | |
5093 | } | |
5094 | ||
5095 | out_unlock: | |
5096 | mutex_unlock(&cgroup_mutex); | |
5097 | put_task_struct(tsk); | |
5098 | out_free: | |
5099 | kfree(buf); | |
5100 | out: | |
5101 | return retval; | |
5102 | } | |
5103 | ||
a424316c PM |
5104 | /* Display information about each subsystem and each hierarchy */ |
5105 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
5106 | { | |
30159ec7 | 5107 | struct cgroup_subsys *ss; |
a424316c | 5108 | int i; |
a424316c | 5109 | |
8bab8dde | 5110 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
5111 | /* |
5112 | * ideally we don't want subsystems moving around while we do this. | |
5113 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5114 | * subsys/hierarchy state. | |
5115 | */ | |
a424316c | 5116 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
5117 | |
5118 | for_each_subsys(ss, i) | |
2c6ab6d2 PM |
5119 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
5120 | ss->name, ss->root->hierarchy_id, | |
8bab8dde | 5121 | ss->root->number_of_cgroups, !ss->disabled); |
30159ec7 | 5122 | |
a424316c PM |
5123 | mutex_unlock(&cgroup_mutex); |
5124 | return 0; | |
5125 | } | |
5126 | ||
5127 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5128 | { | |
9dce07f1 | 5129 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5130 | } |
5131 | ||
828c0950 | 5132 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5133 | .open = cgroupstats_open, |
5134 | .read = seq_read, | |
5135 | .llseek = seq_lseek, | |
5136 | .release = single_release, | |
5137 | }; | |
5138 | ||
b4f48b63 PM |
5139 | /** |
5140 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 5141 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
5142 | * |
5143 | * Description: A task inherits its parent's cgroup at fork(). | |
5144 | * | |
5145 | * A pointer to the shared css_set was automatically copied in | |
5146 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
9bb71308 TH |
5147 | * it was not made under the protection of RCU or cgroup_mutex, so |
5148 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might | |
5149 | * have already changed current->cgroups, allowing the previously | |
5150 | * referenced cgroup group to be removed and freed. | |
b4f48b63 PM |
5151 | * |
5152 | * At the point that cgroup_fork() is called, 'current' is the parent | |
5153 | * task, and the passed argument 'child' points to the child task. | |
5154 | */ | |
5155 | void cgroup_fork(struct task_struct *child) | |
5156 | { | |
9bb71308 | 5157 | task_lock(current); |
a8ad805c | 5158 | get_css_set(task_css_set(current)); |
817929ec | 5159 | child->cgroups = current->cgroups; |
9bb71308 | 5160 | task_unlock(current); |
817929ec | 5161 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5162 | } |
5163 | ||
817929ec | 5164 | /** |
a043e3b2 LZ |
5165 | * cgroup_post_fork - called on a new task after adding it to the task list |
5166 | * @child: the task in question | |
5167 | * | |
5edee61e TH |
5168 | * Adds the task to the list running through its css_set if necessary and |
5169 | * call the subsystem fork() callbacks. Has to be after the task is | |
5170 | * visible on the task list in case we race with the first call to | |
0942eeee | 5171 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 5172 | * list. |
a043e3b2 | 5173 | */ |
817929ec PM |
5174 | void cgroup_post_fork(struct task_struct *child) |
5175 | { | |
30159ec7 | 5176 | struct cgroup_subsys *ss; |
5edee61e TH |
5177 | int i; |
5178 | ||
3ce3230a FW |
5179 | /* |
5180 | * use_task_css_set_links is set to 1 before we walk the tasklist | |
5181 | * under the tasklist_lock and we read it here after we added the child | |
5182 | * to the tasklist under the tasklist_lock as well. If the child wasn't | |
5183 | * yet in the tasklist when we walked through it from | |
5184 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value | |
5185 | * should be visible now due to the paired locking and barriers implied | |
5186 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock | |
5187 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock | |
5188 | * lock on fork. | |
5189 | */ | |
817929ec PM |
5190 | if (use_task_css_set_links) { |
5191 | write_lock(&css_set_lock); | |
d8783832 TH |
5192 | task_lock(child); |
5193 | if (list_empty(&child->cg_list)) | |
a8ad805c | 5194 | list_add(&child->cg_list, &task_css_set(child)->tasks); |
d8783832 | 5195 | task_unlock(child); |
817929ec PM |
5196 | write_unlock(&css_set_lock); |
5197 | } | |
5edee61e TH |
5198 | |
5199 | /* | |
5200 | * Call ss->fork(). This must happen after @child is linked on | |
5201 | * css_set; otherwise, @child might change state between ->fork() | |
5202 | * and addition to css_set. | |
5203 | */ | |
5204 | if (need_forkexit_callback) { | |
7d8e0bf5 LZ |
5205 | /* |
5206 | * fork/exit callbacks are supported only for builtin | |
5207 | * subsystems, and the builtin section of the subsys | |
5208 | * array is immutable, so we don't need to lock the | |
5209 | * subsys array here. On the other hand, modular section | |
5210 | * of the array can be freed at module unload, so we | |
5211 | * can't touch that. | |
5212 | */ | |
30159ec7 | 5213 | for_each_builtin_subsys(ss, i) |
5edee61e TH |
5214 | if (ss->fork) |
5215 | ss->fork(child); | |
5edee61e | 5216 | } |
817929ec | 5217 | } |
5edee61e | 5218 | |
b4f48b63 PM |
5219 | /** |
5220 | * cgroup_exit - detach cgroup from exiting task | |
5221 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 5222 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
5223 | * |
5224 | * Description: Detach cgroup from @tsk and release it. | |
5225 | * | |
5226 | * Note that cgroups marked notify_on_release force every task in | |
5227 | * them to take the global cgroup_mutex mutex when exiting. | |
5228 | * This could impact scaling on very large systems. Be reluctant to | |
5229 | * use notify_on_release cgroups where very high task exit scaling | |
5230 | * is required on large systems. | |
5231 | * | |
5232 | * the_top_cgroup_hack: | |
5233 | * | |
5234 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
5235 | * | |
5236 | * We call cgroup_exit() while the task is still competent to | |
5237 | * handle notify_on_release(), then leave the task attached to the | |
5238 | * root cgroup in each hierarchy for the remainder of its exit. | |
5239 | * | |
5240 | * To do this properly, we would increment the reference count on | |
5241 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
5242 | * code we would add a second cgroup function call, to drop that | |
5243 | * reference. This would just create an unnecessary hot spot on | |
5244 | * the top_cgroup reference count, to no avail. | |
5245 | * | |
5246 | * Normally, holding a reference to a cgroup without bumping its | |
5247 | * count is unsafe. The cgroup could go away, or someone could | |
5248 | * attach us to a different cgroup, decrementing the count on | |
5249 | * the first cgroup that we never incremented. But in this case, | |
5250 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
5251 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
5252 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
5253 | */ |
5254 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
5255 | { | |
30159ec7 | 5256 | struct cgroup_subsys *ss; |
5abb8855 | 5257 | struct css_set *cset; |
d41d5a01 | 5258 | int i; |
817929ec PM |
5259 | |
5260 | /* | |
5261 | * Unlink from the css_set task list if necessary. | |
5262 | * Optimistically check cg_list before taking | |
5263 | * css_set_lock | |
5264 | */ | |
5265 | if (!list_empty(&tsk->cg_list)) { | |
5266 | write_lock(&css_set_lock); | |
5267 | if (!list_empty(&tsk->cg_list)) | |
8d258797 | 5268 | list_del_init(&tsk->cg_list); |
817929ec PM |
5269 | write_unlock(&css_set_lock); |
5270 | } | |
5271 | ||
b4f48b63 PM |
5272 | /* Reassign the task to the init_css_set. */ |
5273 | task_lock(tsk); | |
a8ad805c TH |
5274 | cset = task_css_set(tsk); |
5275 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 PZ |
5276 | |
5277 | if (run_callbacks && need_forkexit_callback) { | |
7d8e0bf5 LZ |
5278 | /* |
5279 | * fork/exit callbacks are supported only for builtin | |
5280 | * subsystems, see cgroup_post_fork() for details. | |
5281 | */ | |
30159ec7 | 5282 | for_each_builtin_subsys(ss, i) { |
d41d5a01 | 5283 | if (ss->exit) { |
eb95419b TH |
5284 | struct cgroup_subsys_state *old_css = cset->subsys[i]; |
5285 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 5286 | |
eb95419b | 5287 | ss->exit(css, old_css, tsk); |
d41d5a01 PZ |
5288 | } |
5289 | } | |
5290 | } | |
b4f48b63 | 5291 | task_unlock(tsk); |
d41d5a01 | 5292 | |
5abb8855 | 5293 | put_css_set_taskexit(cset); |
b4f48b63 | 5294 | } |
697f4161 | 5295 | |
bd89aabc | 5296 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5297 | { |
f50daa70 | 5298 | if (cgroup_is_releasable(cgrp) && |
6f3d828f | 5299 | list_empty(&cgrp->cset_links) && list_empty(&cgrp->children)) { |
f50daa70 LZ |
5300 | /* |
5301 | * Control Group is currently removeable. If it's not | |
81a6a5cd | 5302 | * already queued for a userspace notification, queue |
f50daa70 LZ |
5303 | * it now |
5304 | */ | |
81a6a5cd | 5305 | int need_schedule_work = 0; |
f50daa70 | 5306 | |
cdcc136f | 5307 | raw_spin_lock(&release_list_lock); |
54766d4a | 5308 | if (!cgroup_is_dead(cgrp) && |
bd89aabc PM |
5309 | list_empty(&cgrp->release_list)) { |
5310 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
5311 | need_schedule_work = 1; |
5312 | } | |
cdcc136f | 5313 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
5314 | if (need_schedule_work) |
5315 | schedule_work(&release_agent_work); | |
5316 | } | |
5317 | } | |
5318 | ||
81a6a5cd PM |
5319 | /* |
5320 | * Notify userspace when a cgroup is released, by running the | |
5321 | * configured release agent with the name of the cgroup (path | |
5322 | * relative to the root of cgroup file system) as the argument. | |
5323 | * | |
5324 | * Most likely, this user command will try to rmdir this cgroup. | |
5325 | * | |
5326 | * This races with the possibility that some other task will be | |
5327 | * attached to this cgroup before it is removed, or that some other | |
5328 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5329 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5330 | * unused, and this cgroup will be reprieved from its death sentence, | |
5331 | * to continue to serve a useful existence. Next time it's released, | |
5332 | * we will get notified again, if it still has 'notify_on_release' set. | |
5333 | * | |
5334 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5335 | * means only wait until the task is successfully execve()'d. The | |
5336 | * separate release agent task is forked by call_usermodehelper(), | |
5337 | * then control in this thread returns here, without waiting for the | |
5338 | * release agent task. We don't bother to wait because the caller of | |
5339 | * this routine has no use for the exit status of the release agent | |
5340 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5341 | */ |
81a6a5cd PM |
5342 | static void cgroup_release_agent(struct work_struct *work) |
5343 | { | |
5344 | BUG_ON(work != &release_agent_work); | |
5345 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 5346 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
5347 | while (!list_empty(&release_list)) { |
5348 | char *argv[3], *envp[3]; | |
5349 | int i; | |
e788e066 | 5350 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 5351 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
5352 | struct cgroup, |
5353 | release_list); | |
bd89aabc | 5354 | list_del_init(&cgrp->release_list); |
cdcc136f | 5355 | raw_spin_unlock(&release_list_lock); |
81a6a5cd | 5356 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
e788e066 PM |
5357 | if (!pathbuf) |
5358 | goto continue_free; | |
5359 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
5360 | goto continue_free; | |
5361 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5362 | if (!agentbuf) | |
5363 | goto continue_free; | |
81a6a5cd PM |
5364 | |
5365 | i = 0; | |
e788e066 PM |
5366 | argv[i++] = agentbuf; |
5367 | argv[i++] = pathbuf; | |
81a6a5cd PM |
5368 | argv[i] = NULL; |
5369 | ||
5370 | i = 0; | |
5371 | /* minimal command environment */ | |
5372 | envp[i++] = "HOME=/"; | |
5373 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5374 | envp[i] = NULL; | |
5375 | ||
5376 | /* Drop the lock while we invoke the usermode helper, | |
5377 | * since the exec could involve hitting disk and hence | |
5378 | * be a slow process */ | |
5379 | mutex_unlock(&cgroup_mutex); | |
5380 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 5381 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
5382 | continue_free: |
5383 | kfree(pathbuf); | |
5384 | kfree(agentbuf); | |
cdcc136f | 5385 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 5386 | } |
cdcc136f | 5387 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
5388 | mutex_unlock(&cgroup_mutex); |
5389 | } | |
8bab8dde PM |
5390 | |
5391 | static int __init cgroup_disable(char *str) | |
5392 | { | |
30159ec7 | 5393 | struct cgroup_subsys *ss; |
8bab8dde | 5394 | char *token; |
30159ec7 | 5395 | int i; |
8bab8dde PM |
5396 | |
5397 | while ((token = strsep(&str, ",")) != NULL) { | |
5398 | if (!*token) | |
5399 | continue; | |
be45c900 | 5400 | |
30159ec7 TH |
5401 | /* |
5402 | * cgroup_disable, being at boot time, can't know about | |
5403 | * module subsystems, so we don't worry about them. | |
5404 | */ | |
5405 | for_each_builtin_subsys(ss, i) { | |
8bab8dde PM |
5406 | if (!strcmp(token, ss->name)) { |
5407 | ss->disabled = 1; | |
5408 | printk(KERN_INFO "Disabling %s control group" | |
5409 | " subsystem\n", ss->name); | |
5410 | break; | |
5411 | } | |
5412 | } | |
5413 | } | |
5414 | return 1; | |
5415 | } | |
5416 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
5417 | |
5418 | /* | |
5419 | * Functons for CSS ID. | |
5420 | */ | |
5421 | ||
54766d4a | 5422 | /* to get ID other than 0, this should be called when !cgroup_is_dead() */ |
38460b48 KH |
5423 | unsigned short css_id(struct cgroup_subsys_state *css) |
5424 | { | |
7f0f1546 KH |
5425 | struct css_id *cssid; |
5426 | ||
5427 | /* | |
5428 | * This css_id() can return correct value when somone has refcnt | |
5429 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
5430 | * it's unchanged until freed. | |
5431 | */ | |
d3daf28d | 5432 | cssid = rcu_dereference_raw(css->id); |
38460b48 KH |
5433 | |
5434 | if (cssid) | |
5435 | return cssid->id; | |
5436 | return 0; | |
5437 | } | |
67523c48 | 5438 | EXPORT_SYMBOL_GPL(css_id); |
38460b48 | 5439 | |
747388d7 KH |
5440 | /** |
5441 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
5442 | * @child: the css to be tested. | |
5443 | * @root: the css supporsed to be an ancestor of the child. | |
5444 | * | |
5445 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
91c63734 | 5446 | * this function reads css->id, the caller must hold rcu_read_lock(). |
747388d7 KH |
5447 | * But, considering usual usage, the csses should be valid objects after test. |
5448 | * Assuming that the caller will do some action to the child if this returns | |
5449 | * returns true, the caller must take "child";s reference count. | |
5450 | * If "child" is valid object and this returns true, "root" is valid, too. | |
5451 | */ | |
5452 | ||
38460b48 | 5453 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
0b7f569e | 5454 | const struct cgroup_subsys_state *root) |
38460b48 | 5455 | { |
747388d7 KH |
5456 | struct css_id *child_id; |
5457 | struct css_id *root_id; | |
38460b48 | 5458 | |
747388d7 | 5459 | child_id = rcu_dereference(child->id); |
91c63734 JW |
5460 | if (!child_id) |
5461 | return false; | |
747388d7 | 5462 | root_id = rcu_dereference(root->id); |
91c63734 JW |
5463 | if (!root_id) |
5464 | return false; | |
5465 | if (child_id->depth < root_id->depth) | |
5466 | return false; | |
5467 | if (child_id->stack[root_id->depth] != root_id->id) | |
5468 | return false; | |
5469 | return true; | |
38460b48 KH |
5470 | } |
5471 | ||
38460b48 KH |
5472 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
5473 | { | |
a4ea1cc9 TH |
5474 | struct css_id *id = rcu_dereference_protected(css->id, true); |
5475 | ||
38460b48 KH |
5476 | /* When this is called before css_id initialization, id can be NULL */ |
5477 | if (!id) | |
5478 | return; | |
5479 | ||
5480 | BUG_ON(!ss->use_id); | |
5481 | ||
5482 | rcu_assign_pointer(id->css, NULL); | |
5483 | rcu_assign_pointer(css->id, NULL); | |
42aee6c4 | 5484 | spin_lock(&ss->id_lock); |
38460b48 | 5485 | idr_remove(&ss->idr, id->id); |
42aee6c4 | 5486 | spin_unlock(&ss->id_lock); |
025cea99 | 5487 | kfree_rcu(id, rcu_head); |
38460b48 | 5488 | } |
67523c48 | 5489 | EXPORT_SYMBOL_GPL(free_css_id); |
38460b48 KH |
5490 | |
5491 | /* | |
5492 | * This is called by init or create(). Then, calls to this function are | |
5493 | * always serialized (By cgroup_mutex() at create()). | |
5494 | */ | |
5495 | ||
5496 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
5497 | { | |
5498 | struct css_id *newid; | |
d228d9ec | 5499 | int ret, size; |
38460b48 KH |
5500 | |
5501 | BUG_ON(!ss->use_id); | |
5502 | ||
5503 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
5504 | newid = kzalloc(size, GFP_KERNEL); | |
5505 | if (!newid) | |
5506 | return ERR_PTR(-ENOMEM); | |
d228d9ec TH |
5507 | |
5508 | idr_preload(GFP_KERNEL); | |
42aee6c4 | 5509 | spin_lock(&ss->id_lock); |
38460b48 | 5510 | /* Don't use 0. allocates an ID of 1-65535 */ |
d228d9ec | 5511 | ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT); |
42aee6c4 | 5512 | spin_unlock(&ss->id_lock); |
d228d9ec | 5513 | idr_preload_end(); |
38460b48 KH |
5514 | |
5515 | /* Returns error when there are no free spaces for new ID.*/ | |
d228d9ec | 5516 | if (ret < 0) |
38460b48 | 5517 | goto err_out; |
38460b48 | 5518 | |
d228d9ec | 5519 | newid->id = ret; |
38460b48 KH |
5520 | newid->depth = depth; |
5521 | return newid; | |
38460b48 KH |
5522 | err_out: |
5523 | kfree(newid); | |
d228d9ec | 5524 | return ERR_PTR(ret); |
38460b48 KH |
5525 | |
5526 | } | |
5527 | ||
e6a1105b BB |
5528 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
5529 | struct cgroup_subsys_state *rootcss) | |
38460b48 KH |
5530 | { |
5531 | struct css_id *newid; | |
38460b48 | 5532 | |
42aee6c4 | 5533 | spin_lock_init(&ss->id_lock); |
38460b48 KH |
5534 | idr_init(&ss->idr); |
5535 | ||
38460b48 KH |
5536 | newid = get_new_cssid(ss, 0); |
5537 | if (IS_ERR(newid)) | |
5538 | return PTR_ERR(newid); | |
5539 | ||
5540 | newid->stack[0] = newid->id; | |
a4ea1cc9 TH |
5541 | RCU_INIT_POINTER(newid->css, rootcss); |
5542 | RCU_INIT_POINTER(rootcss->id, newid); | |
38460b48 KH |
5543 | return 0; |
5544 | } | |
5545 | ||
5546 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
5547 | struct cgroup *child) | |
5548 | { | |
5549 | int subsys_id, i, depth = 0; | |
5550 | struct cgroup_subsys_state *parent_css, *child_css; | |
fae9c791 | 5551 | struct css_id *child_id, *parent_id; |
38460b48 KH |
5552 | |
5553 | subsys_id = ss->subsys_id; | |
5554 | parent_css = parent->subsys[subsys_id]; | |
5555 | child_css = child->subsys[subsys_id]; | |
a4ea1cc9 | 5556 | parent_id = rcu_dereference_protected(parent_css->id, true); |
94b3dd0f | 5557 | depth = parent_id->depth + 1; |
38460b48 KH |
5558 | |
5559 | child_id = get_new_cssid(ss, depth); | |
5560 | if (IS_ERR(child_id)) | |
5561 | return PTR_ERR(child_id); | |
5562 | ||
5563 | for (i = 0; i < depth; i++) | |
5564 | child_id->stack[i] = parent_id->stack[i]; | |
5565 | child_id->stack[depth] = child_id->id; | |
5566 | /* | |
5567 | * child_id->css pointer will be set after this cgroup is available | |
5568 | * see cgroup_populate_dir() | |
5569 | */ | |
5570 | rcu_assign_pointer(child_css->id, child_id); | |
5571 | ||
5572 | return 0; | |
5573 | } | |
5574 | ||
5575 | /** | |
5576 | * css_lookup - lookup css by id | |
5577 | * @ss: cgroup subsys to be looked into. | |
5578 | * @id: the id | |
5579 | * | |
5580 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
5581 | * NULL if not. Should be called under rcu_read_lock() | |
5582 | */ | |
5583 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
5584 | { | |
5585 | struct css_id *cssid = NULL; | |
5586 | ||
5587 | BUG_ON(!ss->use_id); | |
5588 | cssid = idr_find(&ss->idr, id); | |
5589 | ||
5590 | if (unlikely(!cssid)) | |
5591 | return NULL; | |
5592 | ||
5593 | return rcu_dereference(cssid->css); | |
5594 | } | |
67523c48 | 5595 | EXPORT_SYMBOL_GPL(css_lookup); |
38460b48 | 5596 | |
e5d1367f SE |
5597 | /* |
5598 | * get corresponding css from file open on cgroupfs directory | |
5599 | */ | |
5600 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
5601 | { | |
5602 | struct cgroup *cgrp; | |
5603 | struct inode *inode; | |
5604 | struct cgroup_subsys_state *css; | |
5605 | ||
496ad9aa | 5606 | inode = file_inode(f); |
e5d1367f SE |
5607 | /* check in cgroup filesystem dir */ |
5608 | if (inode->i_op != &cgroup_dir_inode_operations) | |
5609 | return ERR_PTR(-EBADF); | |
5610 | ||
5611 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
5612 | return ERR_PTR(-EINVAL); | |
5613 | ||
5614 | /* get cgroup */ | |
5615 | cgrp = __d_cgrp(f->f_dentry); | |
5616 | css = cgrp->subsys[id]; | |
5617 | return css ? css : ERR_PTR(-ENOENT); | |
5618 | } | |
5619 | ||
fe693435 | 5620 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
5621 | static struct cgroup_subsys_state * |
5622 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
5623 | { |
5624 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5625 | ||
5626 | if (!css) | |
5627 | return ERR_PTR(-ENOMEM); | |
5628 | ||
5629 | return css; | |
5630 | } | |
5631 | ||
eb95419b | 5632 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 5633 | { |
eb95419b | 5634 | kfree(css); |
fe693435 PM |
5635 | } |
5636 | ||
182446d0 TH |
5637 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
5638 | struct cftype *cft) | |
fe693435 | 5639 | { |
182446d0 | 5640 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
5641 | } |
5642 | ||
182446d0 TH |
5643 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
5644 | struct cftype *cft) | |
fe693435 PM |
5645 | { |
5646 | return (u64)(unsigned long)current->cgroups; | |
5647 | } | |
5648 | ||
182446d0 | 5649 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 5650 | struct cftype *cft) |
fe693435 PM |
5651 | { |
5652 | u64 count; | |
5653 | ||
5654 | rcu_read_lock(); | |
a8ad805c | 5655 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
5656 | rcu_read_unlock(); |
5657 | return count; | |
5658 | } | |
5659 | ||
182446d0 | 5660 | static int current_css_set_cg_links_read(struct cgroup_subsys_state *css, |
7717f7ba PM |
5661 | struct cftype *cft, |
5662 | struct seq_file *seq) | |
5663 | { | |
69d0206c | 5664 | struct cgrp_cset_link *link; |
5abb8855 | 5665 | struct css_set *cset; |
7717f7ba PM |
5666 | |
5667 | read_lock(&css_set_lock); | |
5668 | rcu_read_lock(); | |
5abb8855 | 5669 | cset = rcu_dereference(current->cgroups); |
69d0206c | 5670 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba PM |
5671 | struct cgroup *c = link->cgrp; |
5672 | const char *name; | |
5673 | ||
5674 | if (c->dentry) | |
5675 | name = c->dentry->d_name.name; | |
5676 | else | |
5677 | name = "?"; | |
2c6ab6d2 PM |
5678 | seq_printf(seq, "Root %d group %s\n", |
5679 | c->root->hierarchy_id, name); | |
7717f7ba PM |
5680 | } |
5681 | rcu_read_unlock(); | |
5682 | read_unlock(&css_set_lock); | |
5683 | return 0; | |
5684 | } | |
5685 | ||
5686 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
182446d0 TH |
5687 | static int cgroup_css_links_read(struct cgroup_subsys_state *css, |
5688 | struct cftype *cft, struct seq_file *seq) | |
7717f7ba | 5689 | { |
69d0206c | 5690 | struct cgrp_cset_link *link; |
7717f7ba PM |
5691 | |
5692 | read_lock(&css_set_lock); | |
182446d0 | 5693 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 5694 | struct css_set *cset = link->cset; |
7717f7ba PM |
5695 | struct task_struct *task; |
5696 | int count = 0; | |
5abb8855 TH |
5697 | seq_printf(seq, "css_set %p\n", cset); |
5698 | list_for_each_entry(task, &cset->tasks, cg_list) { | |
7717f7ba PM |
5699 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { |
5700 | seq_puts(seq, " ...\n"); | |
5701 | break; | |
5702 | } else { | |
5703 | seq_printf(seq, " task %d\n", | |
5704 | task_pid_vnr(task)); | |
5705 | } | |
5706 | } | |
5707 | } | |
5708 | read_unlock(&css_set_lock); | |
5709 | return 0; | |
5710 | } | |
5711 | ||
182446d0 | 5712 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 5713 | { |
182446d0 | 5714 | return test_bit(CGRP_RELEASABLE, &css->cgroup->flags); |
fe693435 PM |
5715 | } |
5716 | ||
5717 | static struct cftype debug_files[] = { | |
fe693435 PM |
5718 | { |
5719 | .name = "taskcount", | |
5720 | .read_u64 = debug_taskcount_read, | |
5721 | }, | |
5722 | ||
5723 | { | |
5724 | .name = "current_css_set", | |
5725 | .read_u64 = current_css_set_read, | |
5726 | }, | |
5727 | ||
5728 | { | |
5729 | .name = "current_css_set_refcount", | |
5730 | .read_u64 = current_css_set_refcount_read, | |
5731 | }, | |
5732 | ||
7717f7ba PM |
5733 | { |
5734 | .name = "current_css_set_cg_links", | |
5735 | .read_seq_string = current_css_set_cg_links_read, | |
5736 | }, | |
5737 | ||
5738 | { | |
5739 | .name = "cgroup_css_links", | |
5740 | .read_seq_string = cgroup_css_links_read, | |
5741 | }, | |
5742 | ||
fe693435 PM |
5743 | { |
5744 | .name = "releasable", | |
5745 | .read_u64 = releasable_read, | |
5746 | }, | |
fe693435 | 5747 | |
4baf6e33 TH |
5748 | { } /* terminate */ |
5749 | }; | |
fe693435 PM |
5750 | |
5751 | struct cgroup_subsys debug_subsys = { | |
5752 | .name = "debug", | |
92fb9748 TH |
5753 | .css_alloc = debug_css_alloc, |
5754 | .css_free = debug_css_free, | |
fe693435 | 5755 | .subsys_id = debug_subsys_id, |
4baf6e33 | 5756 | .base_cftypes = debug_files, |
fe693435 PM |
5757 | }; |
5758 | #endif /* CONFIG_CGROUP_DEBUG */ |