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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 | |
28b4c27b TH |
66 | /* css deactivation bias, makes css->refcnt negative to deny new trygets */ |
67 | #define CSS_DEACT_BIAS INT_MIN | |
68 | ||
e25e2cbb TH |
69 | /* |
70 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
71 | * hierarchy must be performed while holding it. | |
72 | * | |
73 | * cgroup_root_mutex nests inside cgroup_mutex and should be held to modify | |
74 | * cgroupfs_root of any cgroup hierarchy - subsys list, flags, | |
75 | * release_agent_path and so on. Modifying requires both cgroup_mutex and | |
76 | * cgroup_root_mutex. Readers can acquire either of the two. This is to | |
77 | * break the following locking order cycle. | |
78 | * | |
79 | * A. cgroup_mutex -> cred_guard_mutex -> s_type->i_mutex_key -> namespace_sem | |
80 | * B. namespace_sem -> cgroup_mutex | |
81 | * | |
82 | * B happens only through cgroup_show_options() and using cgroup_root_mutex | |
83 | * breaks it. | |
84 | */ | |
2219449a TH |
85 | #ifdef CONFIG_PROVE_RCU |
86 | DEFINE_MUTEX(cgroup_mutex); | |
87 | EXPORT_SYMBOL_GPL(cgroup_mutex); /* only for task_subsys_state_check() */ | |
88 | #else | |
81a6a5cd | 89 | static DEFINE_MUTEX(cgroup_mutex); |
2219449a TH |
90 | #endif |
91 | ||
e25e2cbb | 92 | static DEFINE_MUTEX(cgroup_root_mutex); |
81a6a5cd | 93 | |
aae8aab4 BB |
94 | /* |
95 | * Generate an array of cgroup subsystem pointers. At boot time, this is | |
be45c900 | 96 | * populated with the built in subsystems, and modular subsystems are |
aae8aab4 BB |
97 | * registered after that. The mutable section of this array is protected by |
98 | * cgroup_mutex. | |
99 | */ | |
80f4c877 | 100 | #define SUBSYS(_x) [_x ## _subsys_id] = &_x ## _subsys, |
5fc0b025 | 101 | #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) |
aae8aab4 | 102 | static struct cgroup_subsys *subsys[CGROUP_SUBSYS_COUNT] = { |
ddbcc7e8 PM |
103 | #include <linux/cgroup_subsys.h> |
104 | }; | |
105 | ||
ddbcc7e8 PM |
106 | /* |
107 | * The "rootnode" hierarchy is the "dummy hierarchy", reserved for the | |
108 | * subsystems that are otherwise unattached - it never has more than a | |
109 | * single cgroup, and all tasks are part of that cgroup. | |
110 | */ | |
111 | static struct cgroupfs_root rootnode; | |
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 | ||
189 | static LIST_HEAD(roots); | |
817929ec | 190 | static int 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 | |
ddbcc7e8 PM |
199 | /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ |
200 | #define dummytop (&rootnode.top_cgroup) | |
201 | ||
65dff759 LZ |
202 | static struct cgroup_name root_cgroup_name = { .name = "/" }; |
203 | ||
ddbcc7e8 | 204 | /* This flag indicates whether tasks in the fork and exit paths should |
a043e3b2 LZ |
205 | * check for fork/exit handlers to call. This avoids us having to do |
206 | * extra work in the fork/exit path if none of the subsystems need to | |
207 | * be called. | |
ddbcc7e8 | 208 | */ |
8947f9d5 | 209 | static int need_forkexit_callback __read_mostly; |
ddbcc7e8 | 210 | |
42809dd4 | 211 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
879a3d9d G |
212 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
213 | struct cftype cfts[], bool is_add); | |
42809dd4 | 214 | |
8e3bbf42 SQ |
215 | static int css_unbias_refcnt(int refcnt) |
216 | { | |
217 | return refcnt >= 0 ? refcnt : refcnt - CSS_DEACT_BIAS; | |
218 | } | |
219 | ||
28b4c27b TH |
220 | /* the current nr of refs, always >= 0 whether @css is deactivated or not */ |
221 | static int css_refcnt(struct cgroup_subsys_state *css) | |
222 | { | |
223 | int v = atomic_read(&css->refcnt); | |
224 | ||
8e3bbf42 | 225 | return css_unbias_refcnt(v); |
28b4c27b TH |
226 | } |
227 | ||
ddbcc7e8 | 228 | /* convenient tests for these bits */ |
bd89aabc | 229 | inline int cgroup_is_removed(const struct cgroup *cgrp) |
ddbcc7e8 | 230 | { |
bd89aabc | 231 | return test_bit(CGRP_REMOVED, &cgrp->flags); |
ddbcc7e8 PM |
232 | } |
233 | ||
78574cf9 LZ |
234 | /** |
235 | * cgroup_is_descendant - test ancestry | |
236 | * @cgrp: the cgroup to be tested | |
237 | * @ancestor: possible ancestor of @cgrp | |
238 | * | |
239 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
240 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
241 | * and @ancestor are accessible. | |
242 | */ | |
243 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
244 | { | |
245 | while (cgrp) { | |
246 | if (cgrp == ancestor) | |
247 | return true; | |
248 | cgrp = cgrp->parent; | |
249 | } | |
250 | return false; | |
251 | } | |
252 | EXPORT_SYMBOL_GPL(cgroup_is_descendant); | |
ddbcc7e8 | 253 | |
e9685a03 | 254 | static int cgroup_is_releasable(const struct cgroup *cgrp) |
81a6a5cd PM |
255 | { |
256 | const int bits = | |
bd89aabc PM |
257 | (1 << CGRP_RELEASABLE) | |
258 | (1 << CGRP_NOTIFY_ON_RELEASE); | |
259 | return (cgrp->flags & bits) == bits; | |
81a6a5cd PM |
260 | } |
261 | ||
e9685a03 | 262 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 263 | { |
bd89aabc | 264 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
265 | } |
266 | ||
ddbcc7e8 PM |
267 | /* |
268 | * for_each_subsys() allows you to iterate on each subsystem attached to | |
269 | * an active hierarchy | |
270 | */ | |
271 | #define for_each_subsys(_root, _ss) \ | |
272 | list_for_each_entry(_ss, &_root->subsys_list, sibling) | |
273 | ||
e5f6a860 LZ |
274 | /* for_each_active_root() allows you to iterate across the active hierarchies */ |
275 | #define for_each_active_root(_root) \ | |
ddbcc7e8 PM |
276 | list_for_each_entry(_root, &roots, root_list) |
277 | ||
f6ea9372 TH |
278 | static inline struct cgroup *__d_cgrp(struct dentry *dentry) |
279 | { | |
280 | return dentry->d_fsdata; | |
281 | } | |
282 | ||
05ef1d7c | 283 | static inline struct cfent *__d_cfe(struct dentry *dentry) |
f6ea9372 TH |
284 | { |
285 | return dentry->d_fsdata; | |
286 | } | |
287 | ||
05ef1d7c TH |
288 | static inline struct cftype *__d_cft(struct dentry *dentry) |
289 | { | |
290 | return __d_cfe(dentry)->type; | |
291 | } | |
292 | ||
7ae1bad9 TH |
293 | /** |
294 | * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. | |
295 | * @cgrp: the cgroup to be checked for liveness | |
296 | * | |
47cfcd09 TH |
297 | * On success, returns true; the mutex should be later unlocked. On |
298 | * failure returns false with no lock held. | |
7ae1bad9 | 299 | */ |
b9777cf8 | 300 | static bool cgroup_lock_live_group(struct cgroup *cgrp) |
7ae1bad9 TH |
301 | { |
302 | mutex_lock(&cgroup_mutex); | |
303 | if (cgroup_is_removed(cgrp)) { | |
304 | mutex_unlock(&cgroup_mutex); | |
305 | return false; | |
306 | } | |
307 | return true; | |
308 | } | |
7ae1bad9 | 309 | |
81a6a5cd PM |
310 | /* the list of cgroups eligible for automatic release. Protected by |
311 | * release_list_lock */ | |
312 | static LIST_HEAD(release_list); | |
cdcc136f | 313 | static DEFINE_RAW_SPINLOCK(release_list_lock); |
81a6a5cd PM |
314 | static void cgroup_release_agent(struct work_struct *work); |
315 | static DECLARE_WORK(release_agent_work, cgroup_release_agent); | |
bd89aabc | 316 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 317 | |
817929ec PM |
318 | /* Link structure for associating css_set objects with cgroups */ |
319 | struct cg_cgroup_link { | |
320 | /* | |
321 | * List running through cg_cgroup_links associated with a | |
322 | * cgroup, anchored on cgroup->css_sets | |
323 | */ | |
bd89aabc | 324 | struct list_head cgrp_link_list; |
7717f7ba | 325 | struct cgroup *cgrp; |
817929ec PM |
326 | /* |
327 | * List running through cg_cgroup_links pointing at a | |
328 | * single css_set object, anchored on css_set->cg_links | |
329 | */ | |
330 | struct list_head cg_link_list; | |
331 | struct css_set *cg; | |
332 | }; | |
333 | ||
334 | /* The default css_set - used by init and its children prior to any | |
335 | * hierarchies being mounted. It contains a pointer to the root state | |
336 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
337 | * reference-counted, to improve performance when child cgroups | |
338 | * haven't been created. | |
339 | */ | |
340 | ||
341 | static struct css_set init_css_set; | |
342 | static struct cg_cgroup_link init_css_set_link; | |
343 | ||
e6a1105b BB |
344 | static int cgroup_init_idr(struct cgroup_subsys *ss, |
345 | struct cgroup_subsys_state *css); | |
38460b48 | 346 | |
817929ec PM |
347 | /* css_set_lock protects the list of css_set objects, and the |
348 | * chain of tasks off each css_set. Nests outside task->alloc_lock | |
349 | * due to cgroup_iter_start() */ | |
350 | static DEFINE_RWLOCK(css_set_lock); | |
351 | static int css_set_count; | |
352 | ||
7717f7ba PM |
353 | /* |
354 | * hash table for cgroup groups. This improves the performance to find | |
355 | * an existing css_set. This hash doesn't (currently) take into | |
356 | * account cgroups in empty hierarchies. | |
357 | */ | |
472b1053 | 358 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 359 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 360 | |
0ac801fe | 361 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 LZ |
362 | { |
363 | int i; | |
0ac801fe | 364 | unsigned long key = 0UL; |
472b1053 LZ |
365 | |
366 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) | |
0ac801fe LZ |
367 | key += (unsigned long)css[i]; |
368 | key = (key >> 16) ^ key; | |
472b1053 | 369 | |
0ac801fe | 370 | return key; |
472b1053 LZ |
371 | } |
372 | ||
817929ec PM |
373 | /* We don't maintain the lists running through each css_set to its |
374 | * task until after the first call to cgroup_iter_start(). This | |
375 | * reduces the fork()/exit() overhead for people who have cgroups | |
376 | * compiled into their kernel but not actually in use */ | |
8947f9d5 | 377 | static int use_task_css_set_links __read_mostly; |
817929ec | 378 | |
2c6ab6d2 | 379 | static void __put_css_set(struct css_set *cg, int taskexit) |
b4f48b63 | 380 | { |
71cbb949 KM |
381 | struct cg_cgroup_link *link; |
382 | struct cg_cgroup_link *saved_link; | |
146aa1bd LJ |
383 | /* |
384 | * Ensure that the refcount doesn't hit zero while any readers | |
385 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
386 | * rwlock | |
387 | */ | |
388 | if (atomic_add_unless(&cg->refcount, -1, 1)) | |
389 | return; | |
390 | write_lock(&css_set_lock); | |
391 | if (!atomic_dec_and_test(&cg->refcount)) { | |
392 | write_unlock(&css_set_lock); | |
393 | return; | |
394 | } | |
81a6a5cd | 395 | |
2c6ab6d2 | 396 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
0ac801fe | 397 | hash_del(&cg->hlist); |
2c6ab6d2 PM |
398 | css_set_count--; |
399 | ||
400 | list_for_each_entry_safe(link, saved_link, &cg->cg_links, | |
401 | cg_link_list) { | |
402 | struct cgroup *cgrp = link->cgrp; | |
403 | list_del(&link->cg_link_list); | |
404 | list_del(&link->cgrp_link_list); | |
71b5707e LZ |
405 | |
406 | /* | |
407 | * We may not be holding cgroup_mutex, and if cgrp->count is | |
408 | * dropped to 0 the cgroup can be destroyed at any time, hence | |
409 | * rcu_read_lock is used to keep it alive. | |
410 | */ | |
411 | rcu_read_lock(); | |
bd89aabc PM |
412 | if (atomic_dec_and_test(&cgrp->count) && |
413 | notify_on_release(cgrp)) { | |
81a6a5cd | 414 | if (taskexit) |
bd89aabc PM |
415 | set_bit(CGRP_RELEASABLE, &cgrp->flags); |
416 | check_for_release(cgrp); | |
81a6a5cd | 417 | } |
71b5707e | 418 | rcu_read_unlock(); |
2c6ab6d2 PM |
419 | |
420 | kfree(link); | |
81a6a5cd | 421 | } |
2c6ab6d2 PM |
422 | |
423 | write_unlock(&css_set_lock); | |
30088ad8 | 424 | kfree_rcu(cg, rcu_head); |
b4f48b63 PM |
425 | } |
426 | ||
817929ec PM |
427 | /* |
428 | * refcounted get/put for css_set objects | |
429 | */ | |
430 | static inline void get_css_set(struct css_set *cg) | |
431 | { | |
146aa1bd | 432 | atomic_inc(&cg->refcount); |
817929ec PM |
433 | } |
434 | ||
435 | static inline void put_css_set(struct css_set *cg) | |
436 | { | |
146aa1bd | 437 | __put_css_set(cg, 0); |
817929ec PM |
438 | } |
439 | ||
81a6a5cd PM |
440 | static inline void put_css_set_taskexit(struct css_set *cg) |
441 | { | |
146aa1bd | 442 | __put_css_set(cg, 1); |
81a6a5cd PM |
443 | } |
444 | ||
7717f7ba PM |
445 | /* |
446 | * compare_css_sets - helper function for find_existing_css_set(). | |
447 | * @cg: candidate css_set being tested | |
448 | * @old_cg: existing css_set for a task | |
449 | * @new_cgrp: cgroup that's being entered by the task | |
450 | * @template: desired set of css pointers in css_set (pre-calculated) | |
451 | * | |
452 | * Returns true if "cg" matches "old_cg" except for the hierarchy | |
453 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". | |
454 | */ | |
455 | static bool compare_css_sets(struct css_set *cg, | |
456 | struct css_set *old_cg, | |
457 | struct cgroup *new_cgrp, | |
458 | struct cgroup_subsys_state *template[]) | |
459 | { | |
460 | struct list_head *l1, *l2; | |
461 | ||
462 | if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { | |
463 | /* Not all subsystems matched */ | |
464 | return false; | |
465 | } | |
466 | ||
467 | /* | |
468 | * Compare cgroup pointers in order to distinguish between | |
469 | * different cgroups in heirarchies with no subsystems. We | |
470 | * could get by with just this check alone (and skip the | |
471 | * memcmp above) but on most setups the memcmp check will | |
472 | * avoid the need for this more expensive check on almost all | |
473 | * candidates. | |
474 | */ | |
475 | ||
476 | l1 = &cg->cg_links; | |
477 | l2 = &old_cg->cg_links; | |
478 | while (1) { | |
479 | struct cg_cgroup_link *cgl1, *cgl2; | |
480 | struct cgroup *cg1, *cg2; | |
481 | ||
482 | l1 = l1->next; | |
483 | l2 = l2->next; | |
484 | /* See if we reached the end - both lists are equal length. */ | |
485 | if (l1 == &cg->cg_links) { | |
486 | BUG_ON(l2 != &old_cg->cg_links); | |
487 | break; | |
488 | } else { | |
489 | BUG_ON(l2 == &old_cg->cg_links); | |
490 | } | |
491 | /* Locate the cgroups associated with these links. */ | |
492 | cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); | |
493 | cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); | |
494 | cg1 = cgl1->cgrp; | |
495 | cg2 = cgl2->cgrp; | |
496 | /* Hierarchies should be linked in the same order. */ | |
497 | BUG_ON(cg1->root != cg2->root); | |
498 | ||
499 | /* | |
500 | * If this hierarchy is the hierarchy of the cgroup | |
501 | * that's changing, then we need to check that this | |
502 | * css_set points to the new cgroup; if it's any other | |
503 | * hierarchy, then this css_set should point to the | |
504 | * same cgroup as the old css_set. | |
505 | */ | |
506 | if (cg1->root == new_cgrp->root) { | |
507 | if (cg1 != new_cgrp) | |
508 | return false; | |
509 | } else { | |
510 | if (cg1 != cg2) | |
511 | return false; | |
512 | } | |
513 | } | |
514 | return true; | |
515 | } | |
516 | ||
817929ec PM |
517 | /* |
518 | * find_existing_css_set() is a helper for | |
519 | * find_css_set(), and checks to see whether an existing | |
472b1053 | 520 | * css_set is suitable. |
817929ec PM |
521 | * |
522 | * oldcg: the cgroup group that we're using before the cgroup | |
523 | * transition | |
524 | * | |
bd89aabc | 525 | * cgrp: the cgroup that we're moving into |
817929ec PM |
526 | * |
527 | * template: location in which to build the desired set of subsystem | |
528 | * state objects for the new cgroup group | |
529 | */ | |
817929ec PM |
530 | static struct css_set *find_existing_css_set( |
531 | struct css_set *oldcg, | |
bd89aabc | 532 | struct cgroup *cgrp, |
817929ec | 533 | struct cgroup_subsys_state *template[]) |
b4f48b63 PM |
534 | { |
535 | int i; | |
bd89aabc | 536 | struct cgroupfs_root *root = cgrp->root; |
472b1053 | 537 | struct css_set *cg; |
0ac801fe | 538 | unsigned long key; |
817929ec | 539 | |
aae8aab4 BB |
540 | /* |
541 | * Build the set of subsystem state objects that we want to see in the | |
542 | * new css_set. while subsystems can change globally, the entries here | |
543 | * won't change, so no need for locking. | |
544 | */ | |
817929ec | 545 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
a1a71b45 | 546 | if (root->subsys_mask & (1UL << i)) { |
817929ec PM |
547 | /* Subsystem is in this hierarchy. So we want |
548 | * the subsystem state from the new | |
549 | * cgroup */ | |
bd89aabc | 550 | template[i] = cgrp->subsys[i]; |
817929ec PM |
551 | } else { |
552 | /* Subsystem is not in this hierarchy, so we | |
553 | * don't want to change the subsystem state */ | |
554 | template[i] = oldcg->subsys[i]; | |
555 | } | |
556 | } | |
557 | ||
0ac801fe | 558 | key = css_set_hash(template); |
b67bfe0d | 559 | hash_for_each_possible(css_set_table, cg, hlist, key) { |
7717f7ba PM |
560 | if (!compare_css_sets(cg, oldcg, cgrp, template)) |
561 | continue; | |
562 | ||
563 | /* This css_set matches what we need */ | |
564 | return cg; | |
472b1053 | 565 | } |
817929ec PM |
566 | |
567 | /* No existing cgroup group matched */ | |
568 | return NULL; | |
569 | } | |
570 | ||
36553434 LZ |
571 | static void free_cg_links(struct list_head *tmp) |
572 | { | |
573 | struct cg_cgroup_link *link; | |
574 | struct cg_cgroup_link *saved_link; | |
575 | ||
576 | list_for_each_entry_safe(link, saved_link, tmp, cgrp_link_list) { | |
577 | list_del(&link->cgrp_link_list); | |
578 | kfree(link); | |
579 | } | |
580 | } | |
581 | ||
817929ec PM |
582 | /* |
583 | * allocate_cg_links() allocates "count" cg_cgroup_link structures | |
bd89aabc | 584 | * and chains them on tmp through their cgrp_link_list fields. Returns 0 on |
817929ec PM |
585 | * success or a negative error |
586 | */ | |
817929ec PM |
587 | static int allocate_cg_links(int count, struct list_head *tmp) |
588 | { | |
589 | struct cg_cgroup_link *link; | |
590 | int i; | |
591 | INIT_LIST_HEAD(tmp); | |
592 | for (i = 0; i < count; i++) { | |
593 | link = kmalloc(sizeof(*link), GFP_KERNEL); | |
594 | if (!link) { | |
36553434 | 595 | free_cg_links(tmp); |
817929ec PM |
596 | return -ENOMEM; |
597 | } | |
bd89aabc | 598 | list_add(&link->cgrp_link_list, tmp); |
817929ec PM |
599 | } |
600 | return 0; | |
601 | } | |
602 | ||
c12f65d4 LZ |
603 | /** |
604 | * link_css_set - a helper function to link a css_set to a cgroup | |
605 | * @tmp_cg_links: cg_cgroup_link objects allocated by allocate_cg_links() | |
606 | * @cg: the css_set to be linked | |
607 | * @cgrp: the destination cgroup | |
608 | */ | |
609 | static void link_css_set(struct list_head *tmp_cg_links, | |
610 | struct css_set *cg, struct cgroup *cgrp) | |
611 | { | |
612 | struct cg_cgroup_link *link; | |
613 | ||
614 | BUG_ON(list_empty(tmp_cg_links)); | |
615 | link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, | |
616 | cgrp_link_list); | |
617 | link->cg = cg; | |
7717f7ba | 618 | link->cgrp = cgrp; |
2c6ab6d2 | 619 | atomic_inc(&cgrp->count); |
c12f65d4 | 620 | list_move(&link->cgrp_link_list, &cgrp->css_sets); |
7717f7ba PM |
621 | /* |
622 | * Always add links to the tail of the list so that the list | |
623 | * is sorted by order of hierarchy creation | |
624 | */ | |
625 | list_add_tail(&link->cg_link_list, &cg->cg_links); | |
c12f65d4 LZ |
626 | } |
627 | ||
817929ec PM |
628 | /* |
629 | * find_css_set() takes an existing cgroup group and a | |
630 | * cgroup object, and returns a css_set object that's | |
631 | * equivalent to the old group, but with the given cgroup | |
632 | * substituted into the appropriate hierarchy. Must be called with | |
633 | * cgroup_mutex held | |
634 | */ | |
817929ec | 635 | static struct css_set *find_css_set( |
bd89aabc | 636 | struct css_set *oldcg, struct cgroup *cgrp) |
817929ec PM |
637 | { |
638 | struct css_set *res; | |
639 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; | |
817929ec PM |
640 | |
641 | struct list_head tmp_cg_links; | |
817929ec | 642 | |
7717f7ba | 643 | struct cg_cgroup_link *link; |
0ac801fe | 644 | unsigned long key; |
472b1053 | 645 | |
817929ec PM |
646 | /* First see if we already have a cgroup group that matches |
647 | * the desired set */ | |
7e9abd89 | 648 | read_lock(&css_set_lock); |
bd89aabc | 649 | res = find_existing_css_set(oldcg, cgrp, template); |
817929ec PM |
650 | if (res) |
651 | get_css_set(res); | |
7e9abd89 | 652 | read_unlock(&css_set_lock); |
817929ec PM |
653 | |
654 | if (res) | |
655 | return res; | |
656 | ||
657 | res = kmalloc(sizeof(*res), GFP_KERNEL); | |
658 | if (!res) | |
659 | return NULL; | |
660 | ||
661 | /* Allocate all the cg_cgroup_link objects that we'll need */ | |
662 | if (allocate_cg_links(root_count, &tmp_cg_links) < 0) { | |
663 | kfree(res); | |
664 | return NULL; | |
665 | } | |
666 | ||
146aa1bd | 667 | atomic_set(&res->refcount, 1); |
817929ec PM |
668 | INIT_LIST_HEAD(&res->cg_links); |
669 | INIT_LIST_HEAD(&res->tasks); | |
472b1053 | 670 | INIT_HLIST_NODE(&res->hlist); |
817929ec PM |
671 | |
672 | /* Copy the set of subsystem state objects generated in | |
673 | * find_existing_css_set() */ | |
674 | memcpy(res->subsys, template, sizeof(res->subsys)); | |
675 | ||
676 | write_lock(&css_set_lock); | |
677 | /* Add reference counts and links from the new css_set. */ | |
7717f7ba PM |
678 | list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { |
679 | struct cgroup *c = link->cgrp; | |
680 | if (c->root == cgrp->root) | |
681 | c = cgrp; | |
682 | link_css_set(&tmp_cg_links, res, c); | |
683 | } | |
817929ec PM |
684 | |
685 | BUG_ON(!list_empty(&tmp_cg_links)); | |
686 | ||
817929ec | 687 | css_set_count++; |
472b1053 LZ |
688 | |
689 | /* Add this cgroup group to the hash table */ | |
0ac801fe LZ |
690 | key = css_set_hash(res->subsys); |
691 | hash_add(css_set_table, &res->hlist, key); | |
472b1053 | 692 | |
817929ec PM |
693 | write_unlock(&css_set_lock); |
694 | ||
695 | return res; | |
b4f48b63 PM |
696 | } |
697 | ||
7717f7ba PM |
698 | /* |
699 | * Return the cgroup for "task" from the given hierarchy. Must be | |
700 | * called with cgroup_mutex held. | |
701 | */ | |
702 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
703 | struct cgroupfs_root *root) | |
704 | { | |
705 | struct css_set *css; | |
706 | struct cgroup *res = NULL; | |
707 | ||
708 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); | |
709 | read_lock(&css_set_lock); | |
710 | /* | |
711 | * No need to lock the task - since we hold cgroup_mutex the | |
712 | * task can't change groups, so the only thing that can happen | |
713 | * is that it exits and its css is set back to init_css_set. | |
714 | */ | |
715 | css = task->cgroups; | |
716 | if (css == &init_css_set) { | |
717 | res = &root->top_cgroup; | |
718 | } else { | |
719 | struct cg_cgroup_link *link; | |
720 | list_for_each_entry(link, &css->cg_links, cg_link_list) { | |
721 | struct cgroup *c = link->cgrp; | |
722 | if (c->root == root) { | |
723 | res = c; | |
724 | break; | |
725 | } | |
726 | } | |
727 | } | |
728 | read_unlock(&css_set_lock); | |
729 | BUG_ON(!res); | |
730 | return res; | |
731 | } | |
732 | ||
ddbcc7e8 PM |
733 | /* |
734 | * There is one global cgroup mutex. We also require taking | |
735 | * task_lock() when dereferencing a task's cgroup subsys pointers. | |
736 | * See "The task_lock() exception", at the end of this comment. | |
737 | * | |
738 | * A task must hold cgroup_mutex to modify cgroups. | |
739 | * | |
740 | * Any task can increment and decrement the count field without lock. | |
741 | * So in general, code holding cgroup_mutex can't rely on the count | |
742 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 743 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
744 | * means that no tasks are currently attached, therefore there is no |
745 | * way a task attached to that cgroup can fork (the other way to | |
746 | * increment the count). So code holding cgroup_mutex can safely | |
747 | * assume that if the count is zero, it will stay zero. Similarly, if | |
748 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
749 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
750 | * needs that mutex. | |
751 | * | |
ddbcc7e8 PM |
752 | * The fork and exit callbacks cgroup_fork() and cgroup_exit(), don't |
753 | * (usually) take cgroup_mutex. These are the two most performance | |
754 | * critical pieces of code here. The exception occurs on cgroup_exit(), | |
755 | * when a task in a notify_on_release cgroup exits. Then cgroup_mutex | |
756 | * is taken, and if the cgroup count is zero, a usermode call made | |
a043e3b2 LZ |
757 | * to the release agent with the name of the cgroup (path relative to |
758 | * the root of cgroup file system) as the argument. | |
ddbcc7e8 PM |
759 | * |
760 | * A cgroup can only be deleted if both its 'count' of using tasks | |
761 | * is zero, and its list of 'children' cgroups is empty. Since all | |
762 | * tasks in the system use _some_ cgroup, and since there is always at | |
763 | * least one task in the system (init, pid == 1), therefore, top_cgroup | |
764 | * always has either children cgroups and/or using tasks. So we don't | |
765 | * need a special hack to ensure that top_cgroup cannot be deleted. | |
766 | * | |
767 | * The task_lock() exception | |
768 | * | |
769 | * The need for this exception arises from the action of | |
d0b2fdd2 | 770 | * cgroup_attach_task(), which overwrites one task's cgroup pointer with |
a043e3b2 | 771 | * another. It does so using cgroup_mutex, however there are |
ddbcc7e8 PM |
772 | * several performance critical places that need to reference |
773 | * task->cgroup without the expense of grabbing a system global | |
774 | * mutex. Therefore except as noted below, when dereferencing or, as | |
d0b2fdd2 | 775 | * in cgroup_attach_task(), modifying a task's cgroup pointer we use |
ddbcc7e8 PM |
776 | * task_lock(), which acts on a spinlock (task->alloc_lock) already in |
777 | * the task_struct routinely used for such matters. | |
778 | * | |
779 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 780 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
781 | */ |
782 | ||
ddbcc7e8 PM |
783 | /* |
784 | * A couple of forward declarations required, due to cyclic reference loop: | |
785 | * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> | |
786 | * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations | |
787 | * -> cgroup_mkdir. | |
788 | */ | |
789 | ||
18bb1db3 | 790 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); |
00cd8dd3 | 791 | static struct dentry *cgroup_lookup(struct inode *, struct dentry *, unsigned int); |
ddbcc7e8 | 792 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); |
13af07df AR |
793 | static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, |
794 | unsigned long subsys_mask); | |
6e1d5dcc | 795 | static const struct inode_operations cgroup_dir_inode_operations; |
828c0950 | 796 | static const struct file_operations proc_cgroupstats_operations; |
a424316c PM |
797 | |
798 | static struct backing_dev_info cgroup_backing_dev_info = { | |
d993831f | 799 | .name = "cgroup", |
e4ad08fe | 800 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
a424316c | 801 | }; |
ddbcc7e8 | 802 | |
38460b48 KH |
803 | static int alloc_css_id(struct cgroup_subsys *ss, |
804 | struct cgroup *parent, struct cgroup *child); | |
805 | ||
a5e7ed32 | 806 | static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) |
ddbcc7e8 PM |
807 | { |
808 | struct inode *inode = new_inode(sb); | |
ddbcc7e8 PM |
809 | |
810 | if (inode) { | |
85fe4025 | 811 | inode->i_ino = get_next_ino(); |
ddbcc7e8 | 812 | inode->i_mode = mode; |
76aac0e9 DH |
813 | inode->i_uid = current_fsuid(); |
814 | inode->i_gid = current_fsgid(); | |
ddbcc7e8 PM |
815 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
816 | inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; | |
817 | } | |
818 | return inode; | |
819 | } | |
820 | ||
65dff759 LZ |
821 | static struct cgroup_name *cgroup_alloc_name(struct dentry *dentry) |
822 | { | |
823 | struct cgroup_name *name; | |
824 | ||
825 | name = kmalloc(sizeof(*name) + dentry->d_name.len + 1, GFP_KERNEL); | |
826 | if (!name) | |
827 | return NULL; | |
828 | strcpy(name->name, dentry->d_name.name); | |
829 | return name; | |
830 | } | |
831 | ||
be445626 LZ |
832 | static void cgroup_free_fn(struct work_struct *work) |
833 | { | |
834 | struct cgroup *cgrp = container_of(work, struct cgroup, free_work); | |
835 | struct cgroup_subsys *ss; | |
836 | ||
837 | mutex_lock(&cgroup_mutex); | |
838 | /* | |
839 | * Release the subsystem state objects. | |
840 | */ | |
841 | for_each_subsys(cgrp->root, ss) | |
842 | ss->css_free(cgrp); | |
843 | ||
844 | cgrp->root->number_of_cgroups--; | |
845 | mutex_unlock(&cgroup_mutex); | |
846 | ||
415cf07a LZ |
847 | /* |
848 | * We get a ref to the parent's dentry, and put the ref when | |
849 | * this cgroup is being freed, so it's guaranteed that the | |
850 | * parent won't be destroyed before its children. | |
851 | */ | |
852 | dput(cgrp->parent->dentry); | |
853 | ||
cc20e01c LZ |
854 | ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id); |
855 | ||
be445626 LZ |
856 | /* |
857 | * Drop the active superblock reference that we took when we | |
cc20e01c LZ |
858 | * created the cgroup. This will free cgrp->root, if we are |
859 | * holding the last reference to @sb. | |
be445626 LZ |
860 | */ |
861 | deactivate_super(cgrp->root->sb); | |
862 | ||
863 | /* | |
864 | * if we're getting rid of the cgroup, refcount should ensure | |
865 | * that there are no pidlists left. | |
866 | */ | |
867 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
868 | ||
869 | simple_xattrs_free(&cgrp->xattrs); | |
870 | ||
65dff759 | 871 | kfree(rcu_dereference_raw(cgrp->name)); |
be445626 LZ |
872 | kfree(cgrp); |
873 | } | |
874 | ||
875 | static void cgroup_free_rcu(struct rcu_head *head) | |
876 | { | |
877 | struct cgroup *cgrp = container_of(head, struct cgroup, rcu_head); | |
878 | ||
879 | schedule_work(&cgrp->free_work); | |
880 | } | |
881 | ||
ddbcc7e8 PM |
882 | static void cgroup_diput(struct dentry *dentry, struct inode *inode) |
883 | { | |
884 | /* is dentry a directory ? if so, kfree() associated cgroup */ | |
885 | if (S_ISDIR(inode->i_mode)) { | |
bd89aabc | 886 | struct cgroup *cgrp = dentry->d_fsdata; |
be445626 | 887 | |
bd89aabc | 888 | BUG_ON(!(cgroup_is_removed(cgrp))); |
be445626 | 889 | call_rcu(&cgrp->rcu_head, cgroup_free_rcu); |
05ef1d7c TH |
890 | } else { |
891 | struct cfent *cfe = __d_cfe(dentry); | |
892 | struct cgroup *cgrp = dentry->d_parent->d_fsdata; | |
893 | ||
894 | WARN_ONCE(!list_empty(&cfe->node) && | |
895 | cgrp != &cgrp->root->top_cgroup, | |
896 | "cfe still linked for %s\n", cfe->type->name); | |
712317ad | 897 | simple_xattrs_free(&cfe->xattrs); |
05ef1d7c | 898 | kfree(cfe); |
ddbcc7e8 PM |
899 | } |
900 | iput(inode); | |
901 | } | |
902 | ||
c72a04e3 AV |
903 | static int cgroup_delete(const struct dentry *d) |
904 | { | |
905 | return 1; | |
906 | } | |
907 | ||
ddbcc7e8 PM |
908 | static void remove_dir(struct dentry *d) |
909 | { | |
910 | struct dentry *parent = dget(d->d_parent); | |
911 | ||
912 | d_delete(d); | |
913 | simple_rmdir(parent->d_inode, d); | |
914 | dput(parent); | |
915 | } | |
916 | ||
2739d3cc | 917 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c TH |
918 | { |
919 | struct cfent *cfe; | |
920 | ||
921 | lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); | |
922 | lockdep_assert_held(&cgroup_mutex); | |
923 | ||
2739d3cc LZ |
924 | /* |
925 | * If we're doing cleanup due to failure of cgroup_create(), | |
926 | * the corresponding @cfe may not exist. | |
927 | */ | |
05ef1d7c TH |
928 | list_for_each_entry(cfe, &cgrp->files, node) { |
929 | struct dentry *d = cfe->dentry; | |
930 | ||
931 | if (cft && cfe->type != cft) | |
932 | continue; | |
933 | ||
934 | dget(d); | |
935 | d_delete(d); | |
ce27e317 | 936 | simple_unlink(cgrp->dentry->d_inode, d); |
05ef1d7c TH |
937 | list_del_init(&cfe->node); |
938 | dput(d); | |
939 | ||
2739d3cc | 940 | break; |
ddbcc7e8 | 941 | } |
05ef1d7c TH |
942 | } |
943 | ||
13af07df AR |
944 | /** |
945 | * cgroup_clear_directory - selective removal of base and subsystem files | |
946 | * @dir: directory containing the files | |
947 | * @base_files: true if the base files should be removed | |
948 | * @subsys_mask: mask of the subsystem ids whose files should be removed | |
949 | */ | |
950 | static void cgroup_clear_directory(struct dentry *dir, bool base_files, | |
951 | unsigned long subsys_mask) | |
05ef1d7c TH |
952 | { |
953 | struct cgroup *cgrp = __d_cgrp(dir); | |
13af07df | 954 | struct cgroup_subsys *ss; |
05ef1d7c | 955 | |
13af07df AR |
956 | for_each_subsys(cgrp->root, ss) { |
957 | struct cftype_set *set; | |
958 | if (!test_bit(ss->subsys_id, &subsys_mask)) | |
959 | continue; | |
960 | list_for_each_entry(set, &ss->cftsets, node) | |
879a3d9d | 961 | cgroup_addrm_files(cgrp, NULL, set->cfts, false); |
13af07df AR |
962 | } |
963 | if (base_files) { | |
964 | while (!list_empty(&cgrp->files)) | |
965 | cgroup_rm_file(cgrp, NULL); | |
966 | } | |
ddbcc7e8 PM |
967 | } |
968 | ||
969 | /* | |
970 | * NOTE : the dentry must have been dget()'ed | |
971 | */ | |
972 | static void cgroup_d_remove_dir(struct dentry *dentry) | |
973 | { | |
2fd6b7f5 | 974 | struct dentry *parent; |
13af07df | 975 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
2fd6b7f5 | 976 | |
a1a71b45 | 977 | cgroup_clear_directory(dentry, true, root->subsys_mask); |
ddbcc7e8 | 978 | |
2fd6b7f5 NP |
979 | parent = dentry->d_parent; |
980 | spin_lock(&parent->d_lock); | |
3ec762ad | 981 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
ddbcc7e8 | 982 | list_del_init(&dentry->d_u.d_child); |
2fd6b7f5 NP |
983 | spin_unlock(&dentry->d_lock); |
984 | spin_unlock(&parent->d_lock); | |
ddbcc7e8 PM |
985 | remove_dir(dentry); |
986 | } | |
987 | ||
aae8aab4 | 988 | /* |
cf5d5941 BB |
989 | * Call with cgroup_mutex held. Drops reference counts on modules, including |
990 | * any duplicate ones that parse_cgroupfs_options took. If this function | |
991 | * returns an error, no reference counts are touched. | |
aae8aab4 | 992 | */ |
ddbcc7e8 | 993 | static int rebind_subsystems(struct cgroupfs_root *root, |
a1a71b45 | 994 | unsigned long final_subsys_mask) |
ddbcc7e8 | 995 | { |
a1a71b45 | 996 | unsigned long added_mask, removed_mask; |
bd89aabc | 997 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 PM |
998 | int i; |
999 | ||
aae8aab4 | 1000 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
e25e2cbb | 1001 | BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); |
aae8aab4 | 1002 | |
a1a71b45 AR |
1003 | removed_mask = root->actual_subsys_mask & ~final_subsys_mask; |
1004 | added_mask = final_subsys_mask & ~root->actual_subsys_mask; | |
ddbcc7e8 PM |
1005 | /* Check that any added subsystems are currently free */ |
1006 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
8d53d55d | 1007 | unsigned long bit = 1UL << i; |
ddbcc7e8 | 1008 | struct cgroup_subsys *ss = subsys[i]; |
a1a71b45 | 1009 | if (!(bit & added_mask)) |
ddbcc7e8 | 1010 | continue; |
aae8aab4 BB |
1011 | /* |
1012 | * Nobody should tell us to do a subsys that doesn't exist: | |
1013 | * parse_cgroupfs_options should catch that case and refcounts | |
1014 | * ensure that subsystems won't disappear once selected. | |
1015 | */ | |
1016 | BUG_ON(ss == NULL); | |
ddbcc7e8 PM |
1017 | if (ss->root != &rootnode) { |
1018 | /* Subsystem isn't free */ | |
1019 | return -EBUSY; | |
1020 | } | |
1021 | } | |
1022 | ||
1023 | /* Currently we don't handle adding/removing subsystems when | |
1024 | * any child cgroups exist. This is theoretically supportable | |
1025 | * but involves complex error handling, so it's being left until | |
1026 | * later */ | |
307257cf | 1027 | if (root->number_of_cgroups > 1) |
ddbcc7e8 PM |
1028 | return -EBUSY; |
1029 | ||
1030 | /* Process each subsystem */ | |
1031 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1032 | struct cgroup_subsys *ss = subsys[i]; | |
1033 | unsigned long bit = 1UL << i; | |
a1a71b45 | 1034 | if (bit & added_mask) { |
ddbcc7e8 | 1035 | /* We're binding this subsystem to this hierarchy */ |
aae8aab4 | 1036 | BUG_ON(ss == NULL); |
bd89aabc | 1037 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1038 | BUG_ON(!dummytop->subsys[i]); |
1039 | BUG_ON(dummytop->subsys[i]->cgroup != dummytop); | |
bd89aabc PM |
1040 | cgrp->subsys[i] = dummytop->subsys[i]; |
1041 | cgrp->subsys[i]->cgroup = cgrp; | |
33a68ac1 | 1042 | list_move(&ss->sibling, &root->subsys_list); |
b2aa30f7 | 1043 | ss->root = root; |
ddbcc7e8 | 1044 | if (ss->bind) |
761b3ef5 | 1045 | ss->bind(cgrp); |
cf5d5941 | 1046 | /* refcount was already taken, and we're keeping it */ |
a1a71b45 | 1047 | } else if (bit & removed_mask) { |
ddbcc7e8 | 1048 | /* We're removing this subsystem */ |
aae8aab4 | 1049 | BUG_ON(ss == NULL); |
bd89aabc PM |
1050 | BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); |
1051 | BUG_ON(cgrp->subsys[i]->cgroup != cgrp); | |
ddbcc7e8 | 1052 | if (ss->bind) |
761b3ef5 | 1053 | ss->bind(dummytop); |
ddbcc7e8 | 1054 | dummytop->subsys[i]->cgroup = dummytop; |
bd89aabc | 1055 | cgrp->subsys[i] = NULL; |
b2aa30f7 | 1056 | subsys[i]->root = &rootnode; |
33a68ac1 | 1057 | list_move(&ss->sibling, &rootnode.subsys_list); |
cf5d5941 BB |
1058 | /* subsystem is now free - drop reference on module */ |
1059 | module_put(ss->module); | |
a1a71b45 | 1060 | } else if (bit & final_subsys_mask) { |
ddbcc7e8 | 1061 | /* Subsystem state should already exist */ |
aae8aab4 | 1062 | BUG_ON(ss == NULL); |
bd89aabc | 1063 | BUG_ON(!cgrp->subsys[i]); |
cf5d5941 BB |
1064 | /* |
1065 | * a refcount was taken, but we already had one, so | |
1066 | * drop the extra reference. | |
1067 | */ | |
1068 | module_put(ss->module); | |
1069 | #ifdef CONFIG_MODULE_UNLOAD | |
1070 | BUG_ON(ss->module && !module_refcount(ss->module)); | |
1071 | #endif | |
ddbcc7e8 PM |
1072 | } else { |
1073 | /* Subsystem state shouldn't exist */ | |
bd89aabc | 1074 | BUG_ON(cgrp->subsys[i]); |
ddbcc7e8 PM |
1075 | } |
1076 | } | |
a1a71b45 | 1077 | root->subsys_mask = root->actual_subsys_mask = final_subsys_mask; |
ddbcc7e8 PM |
1078 | |
1079 | return 0; | |
1080 | } | |
1081 | ||
34c80b1d | 1082 | static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) |
ddbcc7e8 | 1083 | { |
34c80b1d | 1084 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; |
ddbcc7e8 PM |
1085 | struct cgroup_subsys *ss; |
1086 | ||
e25e2cbb | 1087 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1088 | for_each_subsys(root, ss) |
1089 | seq_printf(seq, ",%s", ss->name); | |
873fe09e TH |
1090 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) |
1091 | seq_puts(seq, ",sane_behavior"); | |
93438629 | 1092 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1093 | seq_puts(seq, ",noprefix"); |
93438629 | 1094 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1095 | seq_puts(seq, ",xattr"); |
81a6a5cd PM |
1096 | if (strlen(root->release_agent_path)) |
1097 | seq_printf(seq, ",release_agent=%s", root->release_agent_path); | |
2260e7fc | 1098 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags)) |
97978e6d | 1099 | seq_puts(seq, ",clone_children"); |
c6d57f33 PM |
1100 | if (strlen(root->name)) |
1101 | seq_printf(seq, ",name=%s", root->name); | |
e25e2cbb | 1102 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1103 | return 0; |
1104 | } | |
1105 | ||
1106 | struct cgroup_sb_opts { | |
a1a71b45 | 1107 | unsigned long subsys_mask; |
ddbcc7e8 | 1108 | unsigned long flags; |
81a6a5cd | 1109 | char *release_agent; |
2260e7fc | 1110 | bool cpuset_clone_children; |
c6d57f33 | 1111 | char *name; |
2c6ab6d2 PM |
1112 | /* User explicitly requested empty subsystem */ |
1113 | bool none; | |
c6d57f33 PM |
1114 | |
1115 | struct cgroupfs_root *new_root; | |
2c6ab6d2 | 1116 | |
ddbcc7e8 PM |
1117 | }; |
1118 | ||
aae8aab4 BB |
1119 | /* |
1120 | * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call | |
cf5d5941 BB |
1121 | * with cgroup_mutex held to protect the subsys[] array. This function takes |
1122 | * refcounts on subsystems to be used, unless it returns error, in which case | |
1123 | * no refcounts are taken. | |
aae8aab4 | 1124 | */ |
cf5d5941 | 1125 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1126 | { |
32a8cf23 DL |
1127 | char *token, *o = data; |
1128 | bool all_ss = false, one_ss = false; | |
f9ab5b5b | 1129 | unsigned long mask = (unsigned long)-1; |
cf5d5941 BB |
1130 | int i; |
1131 | bool module_pin_failed = false; | |
f9ab5b5b | 1132 | |
aae8aab4 BB |
1133 | BUG_ON(!mutex_is_locked(&cgroup_mutex)); |
1134 | ||
f9ab5b5b LZ |
1135 | #ifdef CONFIG_CPUSETS |
1136 | mask = ~(1UL << cpuset_subsys_id); | |
1137 | #endif | |
ddbcc7e8 | 1138 | |
c6d57f33 | 1139 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1140 | |
1141 | while ((token = strsep(&o, ",")) != NULL) { | |
1142 | if (!*token) | |
1143 | return -EINVAL; | |
32a8cf23 | 1144 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1145 | /* Explicitly have no subsystems */ |
1146 | opts->none = true; | |
32a8cf23 DL |
1147 | continue; |
1148 | } | |
1149 | if (!strcmp(token, "all")) { | |
1150 | /* Mutually exclusive option 'all' + subsystem name */ | |
1151 | if (one_ss) | |
1152 | return -EINVAL; | |
1153 | all_ss = true; | |
1154 | continue; | |
1155 | } | |
873fe09e TH |
1156 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1157 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1158 | continue; | |
1159 | } | |
32a8cf23 | 1160 | if (!strcmp(token, "noprefix")) { |
93438629 | 1161 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1162 | continue; |
1163 | } | |
1164 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1165 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1166 | continue; |
1167 | } | |
03b1cde6 | 1168 | if (!strcmp(token, "xattr")) { |
93438629 | 1169 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1170 | continue; |
1171 | } | |
32a8cf23 | 1172 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1173 | /* Specifying two release agents is forbidden */ |
1174 | if (opts->release_agent) | |
1175 | return -EINVAL; | |
c6d57f33 | 1176 | opts->release_agent = |
e400c285 | 1177 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1178 | if (!opts->release_agent) |
1179 | return -ENOMEM; | |
32a8cf23 DL |
1180 | continue; |
1181 | } | |
1182 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1183 | const char *name = token + 5; |
1184 | /* Can't specify an empty name */ | |
1185 | if (!strlen(name)) | |
1186 | return -EINVAL; | |
1187 | /* Must match [\w.-]+ */ | |
1188 | for (i = 0; i < strlen(name); i++) { | |
1189 | char c = name[i]; | |
1190 | if (isalnum(c)) | |
1191 | continue; | |
1192 | if ((c == '.') || (c == '-') || (c == '_')) | |
1193 | continue; | |
1194 | return -EINVAL; | |
1195 | } | |
1196 | /* Specifying two names is forbidden */ | |
1197 | if (opts->name) | |
1198 | return -EINVAL; | |
1199 | opts->name = kstrndup(name, | |
e400c285 | 1200 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1201 | GFP_KERNEL); |
1202 | if (!opts->name) | |
1203 | return -ENOMEM; | |
32a8cf23 DL |
1204 | |
1205 | continue; | |
1206 | } | |
1207 | ||
1208 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { | |
1209 | struct cgroup_subsys *ss = subsys[i]; | |
1210 | if (ss == NULL) | |
1211 | continue; | |
1212 | if (strcmp(token, ss->name)) | |
1213 | continue; | |
1214 | if (ss->disabled) | |
1215 | continue; | |
1216 | ||
1217 | /* Mutually exclusive option 'all' + subsystem name */ | |
1218 | if (all_ss) | |
1219 | return -EINVAL; | |
a1a71b45 | 1220 | set_bit(i, &opts->subsys_mask); |
32a8cf23 DL |
1221 | one_ss = true; |
1222 | ||
1223 | break; | |
1224 | } | |
1225 | if (i == CGROUP_SUBSYS_COUNT) | |
1226 | return -ENOENT; | |
1227 | } | |
1228 | ||
1229 | /* | |
1230 | * If the 'all' option was specified select all the subsystems, | |
0d19ea86 LZ |
1231 | * otherwise if 'none', 'name=' and a subsystem name options |
1232 | * were not specified, let's default to 'all' | |
32a8cf23 | 1233 | */ |
0d19ea86 | 1234 | if (all_ss || (!one_ss && !opts->none && !opts->name)) { |
32a8cf23 DL |
1235 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
1236 | struct cgroup_subsys *ss = subsys[i]; | |
1237 | if (ss == NULL) | |
1238 | continue; | |
1239 | if (ss->disabled) | |
1240 | continue; | |
a1a71b45 | 1241 | set_bit(i, &opts->subsys_mask); |
ddbcc7e8 PM |
1242 | } |
1243 | } | |
1244 | ||
2c6ab6d2 PM |
1245 | /* Consistency checks */ |
1246 | ||
873fe09e TH |
1247 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1248 | pr_warning("cgroup: sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); | |
1249 | ||
1250 | if (opts->flags & CGRP_ROOT_NOPREFIX) { | |
1251 | pr_err("cgroup: sane_behavior: noprefix is not allowed\n"); | |
1252 | return -EINVAL; | |
1253 | } | |
1254 | ||
1255 | if (opts->cpuset_clone_children) { | |
1256 | pr_err("cgroup: sane_behavior: clone_children is not allowed\n"); | |
1257 | return -EINVAL; | |
1258 | } | |
1259 | } | |
1260 | ||
f9ab5b5b LZ |
1261 | /* |
1262 | * Option noprefix was introduced just for backward compatibility | |
1263 | * with the old cpuset, so we allow noprefix only if mounting just | |
1264 | * the cpuset subsystem. | |
1265 | */ | |
93438629 | 1266 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1267 | return -EINVAL; |
1268 | ||
2c6ab6d2 PM |
1269 | |
1270 | /* Can't specify "none" and some subsystems */ | |
a1a71b45 | 1271 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1272 | return -EINVAL; |
1273 | ||
1274 | /* | |
1275 | * We either have to specify by name or by subsystems. (So all | |
1276 | * empty hierarchies must have a name). | |
1277 | */ | |
a1a71b45 | 1278 | if (!opts->subsys_mask && !opts->name) |
ddbcc7e8 PM |
1279 | return -EINVAL; |
1280 | ||
cf5d5941 BB |
1281 | /* |
1282 | * Grab references on all the modules we'll need, so the subsystems | |
1283 | * don't dance around before rebind_subsystems attaches them. This may | |
1284 | * take duplicate reference counts on a subsystem that's already used, | |
1285 | * but rebind_subsystems handles this case. | |
1286 | */ | |
be45c900 | 1287 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
cf5d5941 BB |
1288 | unsigned long bit = 1UL << i; |
1289 | ||
a1a71b45 | 1290 | if (!(bit & opts->subsys_mask)) |
cf5d5941 BB |
1291 | continue; |
1292 | if (!try_module_get(subsys[i]->module)) { | |
1293 | module_pin_failed = true; | |
1294 | break; | |
1295 | } | |
1296 | } | |
1297 | if (module_pin_failed) { | |
1298 | /* | |
1299 | * oops, one of the modules was going away. this means that we | |
1300 | * raced with a module_delete call, and to the user this is | |
1301 | * essentially a "subsystem doesn't exist" case. | |
1302 | */ | |
be45c900 | 1303 | for (i--; i >= 0; i--) { |
cf5d5941 BB |
1304 | /* drop refcounts only on the ones we took */ |
1305 | unsigned long bit = 1UL << i; | |
1306 | ||
a1a71b45 | 1307 | if (!(bit & opts->subsys_mask)) |
cf5d5941 BB |
1308 | continue; |
1309 | module_put(subsys[i]->module); | |
1310 | } | |
1311 | return -ENOENT; | |
1312 | } | |
1313 | ||
ddbcc7e8 PM |
1314 | return 0; |
1315 | } | |
1316 | ||
a1a71b45 | 1317 | static void drop_parsed_module_refcounts(unsigned long subsys_mask) |
cf5d5941 BB |
1318 | { |
1319 | int i; | |
be45c900 | 1320 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
cf5d5941 BB |
1321 | unsigned long bit = 1UL << i; |
1322 | ||
a1a71b45 | 1323 | if (!(bit & subsys_mask)) |
cf5d5941 BB |
1324 | continue; |
1325 | module_put(subsys[i]->module); | |
1326 | } | |
1327 | } | |
1328 | ||
ddbcc7e8 PM |
1329 | static int cgroup_remount(struct super_block *sb, int *flags, char *data) |
1330 | { | |
1331 | int ret = 0; | |
1332 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1333 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1334 | struct cgroup_sb_opts opts; |
a1a71b45 | 1335 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1336 | |
873fe09e TH |
1337 | if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
1338 | pr_err("cgroup: sane_behavior: remount is not allowed\n"); | |
1339 | return -EINVAL; | |
1340 | } | |
1341 | ||
bd89aabc | 1342 | mutex_lock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 | 1343 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1344 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1345 | |
1346 | /* See what subsystems are wanted */ | |
1347 | ret = parse_cgroupfs_options(data, &opts); | |
1348 | if (ret) | |
1349 | goto out_unlock; | |
1350 | ||
a1a71b45 | 1351 | if (opts.subsys_mask != root->actual_subsys_mask || opts.release_agent) |
8b5a5a9d TH |
1352 | pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n", |
1353 | task_tgid_nr(current), current->comm); | |
1354 | ||
a1a71b45 AR |
1355 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1356 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1357 | |
cf5d5941 BB |
1358 | /* Don't allow flags or name to change at remount */ |
1359 | if (opts.flags != root->flags || | |
1360 | (opts.name && strcmp(opts.name, root->name))) { | |
c6d57f33 | 1361 | ret = -EINVAL; |
a1a71b45 | 1362 | drop_parsed_module_refcounts(opts.subsys_mask); |
c6d57f33 PM |
1363 | goto out_unlock; |
1364 | } | |
1365 | ||
7083d037 G |
1366 | /* |
1367 | * Clear out the files of subsystems that should be removed, do | |
1368 | * this before rebind_subsystems, since rebind_subsystems may | |
1369 | * change this hierarchy's subsys_list. | |
1370 | */ | |
1371 | cgroup_clear_directory(cgrp->dentry, false, removed_mask); | |
1372 | ||
a1a71b45 | 1373 | ret = rebind_subsystems(root, opts.subsys_mask); |
cf5d5941 | 1374 | if (ret) { |
7083d037 G |
1375 | /* rebind_subsystems failed, re-populate the removed files */ |
1376 | cgroup_populate_dir(cgrp, false, removed_mask); | |
a1a71b45 | 1377 | drop_parsed_module_refcounts(opts.subsys_mask); |
0670e08b | 1378 | goto out_unlock; |
cf5d5941 | 1379 | } |
ddbcc7e8 | 1380 | |
13af07df | 1381 | /* re-populate subsystem files */ |
a1a71b45 | 1382 | cgroup_populate_dir(cgrp, false, added_mask); |
ddbcc7e8 | 1383 | |
81a6a5cd PM |
1384 | if (opts.release_agent) |
1385 | strcpy(root->release_agent_path, opts.release_agent); | |
ddbcc7e8 | 1386 | out_unlock: |
66bdc9cf | 1387 | kfree(opts.release_agent); |
c6d57f33 | 1388 | kfree(opts.name); |
e25e2cbb | 1389 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1390 | mutex_unlock(&cgroup_mutex); |
bd89aabc | 1391 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
1392 | return ret; |
1393 | } | |
1394 | ||
b87221de | 1395 | static const struct super_operations cgroup_ops = { |
ddbcc7e8 PM |
1396 | .statfs = simple_statfs, |
1397 | .drop_inode = generic_delete_inode, | |
1398 | .show_options = cgroup_show_options, | |
1399 | .remount_fs = cgroup_remount, | |
1400 | }; | |
1401 | ||
cc31edce PM |
1402 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1403 | { | |
1404 | INIT_LIST_HEAD(&cgrp->sibling); | |
1405 | INIT_LIST_HEAD(&cgrp->children); | |
05ef1d7c | 1406 | INIT_LIST_HEAD(&cgrp->files); |
cc31edce | 1407 | INIT_LIST_HEAD(&cgrp->css_sets); |
2243076a | 1408 | INIT_LIST_HEAD(&cgrp->allcg_node); |
cc31edce | 1409 | INIT_LIST_HEAD(&cgrp->release_list); |
72a8cb30 | 1410 | INIT_LIST_HEAD(&cgrp->pidlists); |
be445626 | 1411 | INIT_WORK(&cgrp->free_work, cgroup_free_fn); |
72a8cb30 | 1412 | mutex_init(&cgrp->pidlist_mutex); |
0dea1168 KS |
1413 | INIT_LIST_HEAD(&cgrp->event_list); |
1414 | spin_lock_init(&cgrp->event_list_lock); | |
03b1cde6 | 1415 | simple_xattrs_init(&cgrp->xattrs); |
cc31edce | 1416 | } |
c6d57f33 | 1417 | |
ddbcc7e8 PM |
1418 | static void init_cgroup_root(struct cgroupfs_root *root) |
1419 | { | |
bd89aabc | 1420 | struct cgroup *cgrp = &root->top_cgroup; |
b0ca5a84 | 1421 | |
ddbcc7e8 PM |
1422 | INIT_LIST_HEAD(&root->subsys_list); |
1423 | INIT_LIST_HEAD(&root->root_list); | |
b0ca5a84 | 1424 | INIT_LIST_HEAD(&root->allcg_list); |
ddbcc7e8 | 1425 | root->number_of_cgroups = 1; |
bd89aabc | 1426 | cgrp->root = root; |
65dff759 | 1427 | cgrp->name = &root_cgroup_name; |
cc31edce | 1428 | init_cgroup_housekeeping(cgrp); |
fddfb02a | 1429 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
ddbcc7e8 PM |
1430 | } |
1431 | ||
fa3ca07e | 1432 | static int cgroup_init_root_id(struct cgroupfs_root *root) |
2c6ab6d2 | 1433 | { |
1a574231 | 1434 | int id; |
2c6ab6d2 | 1435 | |
54e7b4eb TH |
1436 | lockdep_assert_held(&cgroup_mutex); |
1437 | lockdep_assert_held(&cgroup_root_mutex); | |
1438 | ||
1a574231 TH |
1439 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 2, 0, GFP_KERNEL); |
1440 | if (id < 0) | |
1441 | return id; | |
1442 | ||
1443 | root->hierarchy_id = id; | |
fa3ca07e TH |
1444 | return 0; |
1445 | } | |
1446 | ||
1447 | static void cgroup_exit_root_id(struct cgroupfs_root *root) | |
1448 | { | |
54e7b4eb TH |
1449 | lockdep_assert_held(&cgroup_mutex); |
1450 | lockdep_assert_held(&cgroup_root_mutex); | |
1451 | ||
fa3ca07e | 1452 | if (root->hierarchy_id) { |
1a574231 | 1453 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); |
fa3ca07e TH |
1454 | root->hierarchy_id = 0; |
1455 | } | |
2c6ab6d2 PM |
1456 | } |
1457 | ||
ddbcc7e8 PM |
1458 | static int cgroup_test_super(struct super_block *sb, void *data) |
1459 | { | |
c6d57f33 | 1460 | struct cgroup_sb_opts *opts = data; |
ddbcc7e8 PM |
1461 | struct cgroupfs_root *root = sb->s_fs_info; |
1462 | ||
c6d57f33 PM |
1463 | /* If we asked for a name then it must match */ |
1464 | if (opts->name && strcmp(opts->name, root->name)) | |
1465 | return 0; | |
ddbcc7e8 | 1466 | |
2c6ab6d2 PM |
1467 | /* |
1468 | * If we asked for subsystems (or explicitly for no | |
1469 | * subsystems) then they must match | |
1470 | */ | |
a1a71b45 AR |
1471 | if ((opts->subsys_mask || opts->none) |
1472 | && (opts->subsys_mask != root->subsys_mask)) | |
ddbcc7e8 PM |
1473 | return 0; |
1474 | ||
1475 | return 1; | |
1476 | } | |
1477 | ||
c6d57f33 PM |
1478 | static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) |
1479 | { | |
1480 | struct cgroupfs_root *root; | |
1481 | ||
a1a71b45 | 1482 | if (!opts->subsys_mask && !opts->none) |
c6d57f33 PM |
1483 | return NULL; |
1484 | ||
1485 | root = kzalloc(sizeof(*root), GFP_KERNEL); | |
1486 | if (!root) | |
1487 | return ERR_PTR(-ENOMEM); | |
1488 | ||
1489 | init_cgroup_root(root); | |
2c6ab6d2 | 1490 | |
a1a71b45 | 1491 | root->subsys_mask = opts->subsys_mask; |
c6d57f33 | 1492 | root->flags = opts->flags; |
0a950f65 | 1493 | ida_init(&root->cgroup_ida); |
c6d57f33 PM |
1494 | if (opts->release_agent) |
1495 | strcpy(root->release_agent_path, opts->release_agent); | |
1496 | if (opts->name) | |
1497 | strcpy(root->name, opts->name); | |
2260e7fc TH |
1498 | if (opts->cpuset_clone_children) |
1499 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->top_cgroup.flags); | |
c6d57f33 PM |
1500 | return root; |
1501 | } | |
1502 | ||
fa3ca07e | 1503 | static void cgroup_free_root(struct cgroupfs_root *root) |
2c6ab6d2 | 1504 | { |
fa3ca07e TH |
1505 | if (root) { |
1506 | /* hierarhcy ID shoulid already have been released */ | |
1507 | WARN_ON_ONCE(root->hierarchy_id); | |
2c6ab6d2 | 1508 | |
fa3ca07e TH |
1509 | ida_destroy(&root->cgroup_ida); |
1510 | kfree(root); | |
1511 | } | |
2c6ab6d2 PM |
1512 | } |
1513 | ||
ddbcc7e8 PM |
1514 | static int cgroup_set_super(struct super_block *sb, void *data) |
1515 | { | |
1516 | int ret; | |
c6d57f33 PM |
1517 | struct cgroup_sb_opts *opts = data; |
1518 | ||
1519 | /* If we don't have a new root, we can't set up a new sb */ | |
1520 | if (!opts->new_root) | |
1521 | return -EINVAL; | |
1522 | ||
a1a71b45 | 1523 | BUG_ON(!opts->subsys_mask && !opts->none); |
ddbcc7e8 PM |
1524 | |
1525 | ret = set_anon_super(sb, NULL); | |
1526 | if (ret) | |
1527 | return ret; | |
1528 | ||
c6d57f33 PM |
1529 | sb->s_fs_info = opts->new_root; |
1530 | opts->new_root->sb = sb; | |
ddbcc7e8 PM |
1531 | |
1532 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
1533 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
1534 | sb->s_magic = CGROUP_SUPER_MAGIC; | |
1535 | sb->s_op = &cgroup_ops; | |
1536 | ||
1537 | return 0; | |
1538 | } | |
1539 | ||
1540 | static int cgroup_get_rootdir(struct super_block *sb) | |
1541 | { | |
0df6a63f AV |
1542 | static const struct dentry_operations cgroup_dops = { |
1543 | .d_iput = cgroup_diput, | |
c72a04e3 | 1544 | .d_delete = cgroup_delete, |
0df6a63f AV |
1545 | }; |
1546 | ||
ddbcc7e8 PM |
1547 | struct inode *inode = |
1548 | cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); | |
ddbcc7e8 PM |
1549 | |
1550 | if (!inode) | |
1551 | return -ENOMEM; | |
1552 | ||
ddbcc7e8 PM |
1553 | inode->i_fop = &simple_dir_operations; |
1554 | inode->i_op = &cgroup_dir_inode_operations; | |
1555 | /* directories start off with i_nlink == 2 (for "." entry) */ | |
1556 | inc_nlink(inode); | |
48fde701 AV |
1557 | sb->s_root = d_make_root(inode); |
1558 | if (!sb->s_root) | |
ddbcc7e8 | 1559 | return -ENOMEM; |
0df6a63f AV |
1560 | /* for everything else we want ->d_op set */ |
1561 | sb->s_d_op = &cgroup_dops; | |
ddbcc7e8 PM |
1562 | return 0; |
1563 | } | |
1564 | ||
f7e83571 | 1565 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1566 | int flags, const char *unused_dev_name, |
f7e83571 | 1567 | void *data) |
ddbcc7e8 PM |
1568 | { |
1569 | struct cgroup_sb_opts opts; | |
c6d57f33 | 1570 | struct cgroupfs_root *root; |
ddbcc7e8 PM |
1571 | int ret = 0; |
1572 | struct super_block *sb; | |
c6d57f33 | 1573 | struct cgroupfs_root *new_root; |
e25e2cbb | 1574 | struct inode *inode; |
ddbcc7e8 PM |
1575 | |
1576 | /* First find the desired set of subsystems */ | |
aae8aab4 | 1577 | mutex_lock(&cgroup_mutex); |
ddbcc7e8 | 1578 | ret = parse_cgroupfs_options(data, &opts); |
aae8aab4 | 1579 | mutex_unlock(&cgroup_mutex); |
c6d57f33 PM |
1580 | if (ret) |
1581 | goto out_err; | |
ddbcc7e8 | 1582 | |
c6d57f33 PM |
1583 | /* |
1584 | * Allocate a new cgroup root. We may not need it if we're | |
1585 | * reusing an existing hierarchy. | |
1586 | */ | |
1587 | new_root = cgroup_root_from_opts(&opts); | |
1588 | if (IS_ERR(new_root)) { | |
1589 | ret = PTR_ERR(new_root); | |
cf5d5941 | 1590 | goto drop_modules; |
81a6a5cd | 1591 | } |
c6d57f33 | 1592 | opts.new_root = new_root; |
ddbcc7e8 | 1593 | |
c6d57f33 | 1594 | /* Locate an existing or new sb for this hierarchy */ |
9249e17f | 1595 | sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); |
ddbcc7e8 | 1596 | if (IS_ERR(sb)) { |
c6d57f33 | 1597 | ret = PTR_ERR(sb); |
fa3ca07e | 1598 | cgroup_free_root(opts.new_root); |
cf5d5941 | 1599 | goto drop_modules; |
ddbcc7e8 PM |
1600 | } |
1601 | ||
c6d57f33 PM |
1602 | root = sb->s_fs_info; |
1603 | BUG_ON(!root); | |
1604 | if (root == opts.new_root) { | |
1605 | /* We used the new root structure, so this is a new hierarchy */ | |
1606 | struct list_head tmp_cg_links; | |
c12f65d4 | 1607 | struct cgroup *root_cgrp = &root->top_cgroup; |
c6d57f33 | 1608 | struct cgroupfs_root *existing_root; |
2ce9738b | 1609 | const struct cred *cred; |
28fd5dfc | 1610 | int i; |
0ac801fe | 1611 | struct css_set *cg; |
ddbcc7e8 PM |
1612 | |
1613 | BUG_ON(sb->s_root != NULL); | |
1614 | ||
1615 | ret = cgroup_get_rootdir(sb); | |
1616 | if (ret) | |
1617 | goto drop_new_super; | |
817929ec | 1618 | inode = sb->s_root->d_inode; |
ddbcc7e8 | 1619 | |
817929ec | 1620 | mutex_lock(&inode->i_mutex); |
ddbcc7e8 | 1621 | mutex_lock(&cgroup_mutex); |
e25e2cbb | 1622 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 | 1623 | |
e25e2cbb TH |
1624 | /* Check for name clashes with existing mounts */ |
1625 | ret = -EBUSY; | |
1626 | if (strlen(root->name)) | |
1627 | for_each_active_root(existing_root) | |
1628 | if (!strcmp(existing_root->name, root->name)) | |
1629 | goto unlock_drop; | |
c6d57f33 | 1630 | |
817929ec PM |
1631 | /* |
1632 | * We're accessing css_set_count without locking | |
1633 | * css_set_lock here, but that's OK - it can only be | |
1634 | * increased by someone holding cgroup_lock, and | |
1635 | * that's us. The worst that can happen is that we | |
1636 | * have some link structures left over | |
1637 | */ | |
1638 | ret = allocate_cg_links(css_set_count, &tmp_cg_links); | |
e25e2cbb TH |
1639 | if (ret) |
1640 | goto unlock_drop; | |
817929ec | 1641 | |
fa3ca07e TH |
1642 | ret = cgroup_init_root_id(root); |
1643 | if (ret) | |
1644 | goto unlock_drop; | |
1645 | ||
a1a71b45 | 1646 | ret = rebind_subsystems(root, root->subsys_mask); |
ddbcc7e8 | 1647 | if (ret == -EBUSY) { |
c6d57f33 | 1648 | free_cg_links(&tmp_cg_links); |
e25e2cbb | 1649 | goto unlock_drop; |
ddbcc7e8 | 1650 | } |
cf5d5941 BB |
1651 | /* |
1652 | * There must be no failure case after here, since rebinding | |
1653 | * takes care of subsystems' refcounts, which are explicitly | |
1654 | * dropped in the failure exit path. | |
1655 | */ | |
ddbcc7e8 PM |
1656 | |
1657 | /* EBUSY should be the only error here */ | |
1658 | BUG_ON(ret); | |
1659 | ||
1660 | list_add(&root->root_list, &roots); | |
817929ec | 1661 | root_count++; |
ddbcc7e8 | 1662 | |
c12f65d4 | 1663 | sb->s_root->d_fsdata = root_cgrp; |
ddbcc7e8 PM |
1664 | root->top_cgroup.dentry = sb->s_root; |
1665 | ||
817929ec PM |
1666 | /* Link the top cgroup in this hierarchy into all |
1667 | * the css_set objects */ | |
1668 | write_lock(&css_set_lock); | |
b67bfe0d | 1669 | hash_for_each(css_set_table, i, cg, hlist) |
0ac801fe | 1670 | link_css_set(&tmp_cg_links, cg, root_cgrp); |
817929ec PM |
1671 | write_unlock(&css_set_lock); |
1672 | ||
1673 | free_cg_links(&tmp_cg_links); | |
1674 | ||
c12f65d4 | 1675 | BUG_ON(!list_empty(&root_cgrp->children)); |
ddbcc7e8 PM |
1676 | BUG_ON(root->number_of_cgroups != 1); |
1677 | ||
2ce9738b | 1678 | cred = override_creds(&init_cred); |
a1a71b45 | 1679 | cgroup_populate_dir(root_cgrp, true, root->subsys_mask); |
2ce9738b | 1680 | revert_creds(cred); |
e25e2cbb | 1681 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 | 1682 | mutex_unlock(&cgroup_mutex); |
34f77a90 | 1683 | mutex_unlock(&inode->i_mutex); |
c6d57f33 PM |
1684 | } else { |
1685 | /* | |
1686 | * We re-used an existing hierarchy - the new root (if | |
1687 | * any) is not needed | |
1688 | */ | |
fa3ca07e | 1689 | cgroup_free_root(opts.new_root); |
873fe09e TH |
1690 | |
1691 | if (((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) && | |
1692 | root->flags != opts.flags) { | |
1693 | pr_err("cgroup: sane_behavior: new mount options should match the existing superblock\n"); | |
1694 | ret = -EINVAL; | |
1695 | goto drop_new_super; | |
1696 | } | |
1697 | ||
cf5d5941 | 1698 | /* no subsys rebinding, so refcounts don't change */ |
a1a71b45 | 1699 | drop_parsed_module_refcounts(opts.subsys_mask); |
ddbcc7e8 PM |
1700 | } |
1701 | ||
c6d57f33 PM |
1702 | kfree(opts.release_agent); |
1703 | kfree(opts.name); | |
f7e83571 | 1704 | return dget(sb->s_root); |
ddbcc7e8 | 1705 | |
e25e2cbb | 1706 | unlock_drop: |
fa3ca07e | 1707 | cgroup_exit_root_id(root); |
e25e2cbb TH |
1708 | mutex_unlock(&cgroup_root_mutex); |
1709 | mutex_unlock(&cgroup_mutex); | |
1710 | mutex_unlock(&inode->i_mutex); | |
ddbcc7e8 | 1711 | drop_new_super: |
6f5bbff9 | 1712 | deactivate_locked_super(sb); |
cf5d5941 | 1713 | drop_modules: |
a1a71b45 | 1714 | drop_parsed_module_refcounts(opts.subsys_mask); |
c6d57f33 PM |
1715 | out_err: |
1716 | kfree(opts.release_agent); | |
1717 | kfree(opts.name); | |
f7e83571 | 1718 | return ERR_PTR(ret); |
ddbcc7e8 PM |
1719 | } |
1720 | ||
1721 | static void cgroup_kill_sb(struct super_block *sb) { | |
1722 | struct cgroupfs_root *root = sb->s_fs_info; | |
bd89aabc | 1723 | struct cgroup *cgrp = &root->top_cgroup; |
ddbcc7e8 | 1724 | int ret; |
71cbb949 KM |
1725 | struct cg_cgroup_link *link; |
1726 | struct cg_cgroup_link *saved_link; | |
ddbcc7e8 PM |
1727 | |
1728 | BUG_ON(!root); | |
1729 | ||
1730 | BUG_ON(root->number_of_cgroups != 1); | |
bd89aabc | 1731 | BUG_ON(!list_empty(&cgrp->children)); |
ddbcc7e8 PM |
1732 | |
1733 | mutex_lock(&cgroup_mutex); | |
e25e2cbb | 1734 | mutex_lock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1735 | |
1736 | /* Rebind all subsystems back to the default hierarchy */ | |
1737 | ret = rebind_subsystems(root, 0); | |
1738 | /* Shouldn't be able to fail ... */ | |
1739 | BUG_ON(ret); | |
1740 | ||
817929ec PM |
1741 | /* |
1742 | * Release all the links from css_sets to this hierarchy's | |
1743 | * root cgroup | |
1744 | */ | |
1745 | write_lock(&css_set_lock); | |
71cbb949 KM |
1746 | |
1747 | list_for_each_entry_safe(link, saved_link, &cgrp->css_sets, | |
1748 | cgrp_link_list) { | |
817929ec | 1749 | list_del(&link->cg_link_list); |
bd89aabc | 1750 | list_del(&link->cgrp_link_list); |
817929ec PM |
1751 | kfree(link); |
1752 | } | |
1753 | write_unlock(&css_set_lock); | |
1754 | ||
839ec545 PM |
1755 | if (!list_empty(&root->root_list)) { |
1756 | list_del(&root->root_list); | |
1757 | root_count--; | |
1758 | } | |
e5f6a860 | 1759 | |
fa3ca07e TH |
1760 | cgroup_exit_root_id(root); |
1761 | ||
e25e2cbb | 1762 | mutex_unlock(&cgroup_root_mutex); |
ddbcc7e8 PM |
1763 | mutex_unlock(&cgroup_mutex); |
1764 | ||
03b1cde6 AR |
1765 | simple_xattrs_free(&cgrp->xattrs); |
1766 | ||
ddbcc7e8 | 1767 | kill_litter_super(sb); |
fa3ca07e | 1768 | cgroup_free_root(root); |
ddbcc7e8 PM |
1769 | } |
1770 | ||
1771 | static struct file_system_type cgroup_fs_type = { | |
1772 | .name = "cgroup", | |
f7e83571 | 1773 | .mount = cgroup_mount, |
ddbcc7e8 PM |
1774 | .kill_sb = cgroup_kill_sb, |
1775 | }; | |
1776 | ||
676db4af GKH |
1777 | static struct kobject *cgroup_kobj; |
1778 | ||
a043e3b2 LZ |
1779 | /** |
1780 | * cgroup_path - generate the path of a cgroup | |
1781 | * @cgrp: the cgroup in question | |
1782 | * @buf: the buffer to write the path into | |
1783 | * @buflen: the length of the buffer | |
1784 | * | |
65dff759 LZ |
1785 | * Writes path of cgroup into buf. Returns 0 on success, -errno on error. |
1786 | * | |
1787 | * We can't generate cgroup path using dentry->d_name, as accessing | |
1788 | * dentry->name must be protected by irq-unsafe dentry->d_lock or parent | |
1789 | * inode's i_mutex, while on the other hand cgroup_path() can be called | |
1790 | * with some irq-safe spinlocks held. | |
ddbcc7e8 | 1791 | */ |
bd89aabc | 1792 | int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) |
ddbcc7e8 | 1793 | { |
65dff759 | 1794 | int ret = -ENAMETOOLONG; |
ddbcc7e8 | 1795 | char *start; |
febfcef6 | 1796 | |
da1f296f TH |
1797 | if (!cgrp->parent) { |
1798 | if (strlcpy(buf, "/", buflen) >= buflen) | |
1799 | return -ENAMETOOLONG; | |
ddbcc7e8 PM |
1800 | return 0; |
1801 | } | |
1802 | ||
316eb661 | 1803 | start = buf + buflen - 1; |
316eb661 | 1804 | *start = '\0'; |
9a9686b6 | 1805 | |
65dff759 | 1806 | rcu_read_lock(); |
da1f296f | 1807 | do { |
65dff759 LZ |
1808 | const char *name = cgroup_name(cgrp); |
1809 | int len; | |
1810 | ||
1811 | len = strlen(name); | |
ddbcc7e8 | 1812 | if ((start -= len) < buf) |
65dff759 LZ |
1813 | goto out; |
1814 | memcpy(start, name, len); | |
9a9686b6 | 1815 | |
ddbcc7e8 | 1816 | if (--start < buf) |
65dff759 | 1817 | goto out; |
ddbcc7e8 | 1818 | *start = '/'; |
65dff759 LZ |
1819 | |
1820 | cgrp = cgrp->parent; | |
da1f296f | 1821 | } while (cgrp->parent); |
65dff759 | 1822 | ret = 0; |
ddbcc7e8 | 1823 | memmove(buf, start, buf + buflen - start); |
65dff759 LZ |
1824 | out: |
1825 | rcu_read_unlock(); | |
1826 | return ret; | |
ddbcc7e8 | 1827 | } |
67523c48 | 1828 | EXPORT_SYMBOL_GPL(cgroup_path); |
ddbcc7e8 | 1829 | |
2f7ee569 TH |
1830 | /* |
1831 | * Control Group taskset | |
1832 | */ | |
134d3373 TH |
1833 | struct task_and_cgroup { |
1834 | struct task_struct *task; | |
1835 | struct cgroup *cgrp; | |
61d1d219 | 1836 | struct css_set *cg; |
134d3373 TH |
1837 | }; |
1838 | ||
2f7ee569 TH |
1839 | struct cgroup_taskset { |
1840 | struct task_and_cgroup single; | |
1841 | struct flex_array *tc_array; | |
1842 | int tc_array_len; | |
1843 | int idx; | |
1844 | struct cgroup *cur_cgrp; | |
1845 | }; | |
1846 | ||
1847 | /** | |
1848 | * cgroup_taskset_first - reset taskset and return the first task | |
1849 | * @tset: taskset of interest | |
1850 | * | |
1851 | * @tset iteration is initialized and the first task is returned. | |
1852 | */ | |
1853 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
1854 | { | |
1855 | if (tset->tc_array) { | |
1856 | tset->idx = 0; | |
1857 | return cgroup_taskset_next(tset); | |
1858 | } else { | |
1859 | tset->cur_cgrp = tset->single.cgrp; | |
1860 | return tset->single.task; | |
1861 | } | |
1862 | } | |
1863 | EXPORT_SYMBOL_GPL(cgroup_taskset_first); | |
1864 | ||
1865 | /** | |
1866 | * cgroup_taskset_next - iterate to the next task in taskset | |
1867 | * @tset: taskset of interest | |
1868 | * | |
1869 | * Return the next task in @tset. Iteration must have been initialized | |
1870 | * with cgroup_taskset_first(). | |
1871 | */ | |
1872 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
1873 | { | |
1874 | struct task_and_cgroup *tc; | |
1875 | ||
1876 | if (!tset->tc_array || tset->idx >= tset->tc_array_len) | |
1877 | return NULL; | |
1878 | ||
1879 | tc = flex_array_get(tset->tc_array, tset->idx++); | |
1880 | tset->cur_cgrp = tc->cgrp; | |
1881 | return tc->task; | |
1882 | } | |
1883 | EXPORT_SYMBOL_GPL(cgroup_taskset_next); | |
1884 | ||
1885 | /** | |
1886 | * cgroup_taskset_cur_cgroup - return the matching cgroup for the current task | |
1887 | * @tset: taskset of interest | |
1888 | * | |
1889 | * Return the cgroup for the current (last returned) task of @tset. This | |
1890 | * function must be preceded by either cgroup_taskset_first() or | |
1891 | * cgroup_taskset_next(). | |
1892 | */ | |
1893 | struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset) | |
1894 | { | |
1895 | return tset->cur_cgrp; | |
1896 | } | |
1897 | EXPORT_SYMBOL_GPL(cgroup_taskset_cur_cgroup); | |
1898 | ||
1899 | /** | |
1900 | * cgroup_taskset_size - return the number of tasks in taskset | |
1901 | * @tset: taskset of interest | |
1902 | */ | |
1903 | int cgroup_taskset_size(struct cgroup_taskset *tset) | |
1904 | { | |
1905 | return tset->tc_array ? tset->tc_array_len : 1; | |
1906 | } | |
1907 | EXPORT_SYMBOL_GPL(cgroup_taskset_size); | |
1908 | ||
1909 | ||
74a1166d BB |
1910 | /* |
1911 | * cgroup_task_migrate - move a task from one cgroup to another. | |
1912 | * | |
d0b2fdd2 | 1913 | * Must be called with cgroup_mutex and threadgroup locked. |
74a1166d | 1914 | */ |
1e2ccd1c | 1915 | static void cgroup_task_migrate(struct cgroup *oldcgrp, |
61d1d219 | 1916 | struct task_struct *tsk, struct css_set *newcg) |
74a1166d BB |
1917 | { |
1918 | struct css_set *oldcg; | |
74a1166d BB |
1919 | |
1920 | /* | |
026085ef MSB |
1921 | * We are synchronized through threadgroup_lock() against PF_EXITING |
1922 | * setting such that we can't race against cgroup_exit() changing the | |
1923 | * css_set to init_css_set and dropping the old one. | |
74a1166d | 1924 | */ |
c84cdf75 | 1925 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
74a1166d | 1926 | oldcg = tsk->cgroups; |
74a1166d | 1927 | |
74a1166d | 1928 | task_lock(tsk); |
74a1166d BB |
1929 | rcu_assign_pointer(tsk->cgroups, newcg); |
1930 | task_unlock(tsk); | |
1931 | ||
1932 | /* Update the css_set linked lists if we're using them */ | |
1933 | write_lock(&css_set_lock); | |
1934 | if (!list_empty(&tsk->cg_list)) | |
1935 | list_move(&tsk->cg_list, &newcg->tasks); | |
1936 | write_unlock(&css_set_lock); | |
1937 | ||
1938 | /* | |
1939 | * We just gained a reference on oldcg by taking it from the task. As | |
1940 | * trading it for newcg is protected by cgroup_mutex, we're safe to drop | |
1941 | * it here; it will be freed under RCU. | |
1942 | */ | |
74a1166d | 1943 | set_bit(CGRP_RELEASABLE, &oldcgrp->flags); |
1f5320d5 | 1944 | put_css_set(oldcg); |
74a1166d BB |
1945 | } |
1946 | ||
a043e3b2 | 1947 | /** |
081aa458 | 1948 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup |
74a1166d | 1949 | * @cgrp: the cgroup to attach to |
081aa458 LZ |
1950 | * @tsk: the task or the leader of the threadgroup to be attached |
1951 | * @threadgroup: attach the whole threadgroup? | |
74a1166d | 1952 | * |
257058ae | 1953 | * Call holding cgroup_mutex and the group_rwsem of the leader. Will take |
081aa458 | 1954 | * task_lock of @tsk or each thread in the threadgroup individually in turn. |
74a1166d | 1955 | */ |
47cfcd09 TH |
1956 | static int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, |
1957 | bool threadgroup) | |
74a1166d BB |
1958 | { |
1959 | int retval, i, group_size; | |
1960 | struct cgroup_subsys *ss, *failed_ss = NULL; | |
74a1166d BB |
1961 | struct cgroupfs_root *root = cgrp->root; |
1962 | /* threadgroup list cursor and array */ | |
081aa458 | 1963 | struct task_struct *leader = tsk; |
134d3373 | 1964 | struct task_and_cgroup *tc; |
d846687d | 1965 | struct flex_array *group; |
2f7ee569 | 1966 | struct cgroup_taskset tset = { }; |
74a1166d BB |
1967 | |
1968 | /* | |
1969 | * step 0: in order to do expensive, possibly blocking operations for | |
1970 | * every thread, we cannot iterate the thread group list, since it needs | |
1971 | * rcu or tasklist locked. instead, build an array of all threads in the | |
257058ae TH |
1972 | * group - group_rwsem prevents new threads from appearing, and if |
1973 | * threads exit, this will just be an over-estimate. | |
74a1166d | 1974 | */ |
081aa458 LZ |
1975 | if (threadgroup) |
1976 | group_size = get_nr_threads(tsk); | |
1977 | else | |
1978 | group_size = 1; | |
d846687d | 1979 | /* flex_array supports very large thread-groups better than kmalloc. */ |
134d3373 | 1980 | group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL); |
74a1166d BB |
1981 | if (!group) |
1982 | return -ENOMEM; | |
d846687d | 1983 | /* pre-allocate to guarantee space while iterating in rcu read-side. */ |
3ac1707a | 1984 | retval = flex_array_prealloc(group, 0, group_size, GFP_KERNEL); |
d846687d BB |
1985 | if (retval) |
1986 | goto out_free_group_list; | |
74a1166d | 1987 | |
74a1166d | 1988 | i = 0; |
fb5d2b4c MSB |
1989 | /* |
1990 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
1991 | * already PF_EXITING could be freed from underneath us unless we | |
1992 | * take an rcu_read_lock. | |
1993 | */ | |
1994 | rcu_read_lock(); | |
74a1166d | 1995 | do { |
134d3373 TH |
1996 | struct task_and_cgroup ent; |
1997 | ||
cd3d0952 TH |
1998 | /* @tsk either already exited or can't exit until the end */ |
1999 | if (tsk->flags & PF_EXITING) | |
2000 | continue; | |
2001 | ||
74a1166d BB |
2002 | /* as per above, nr_threads may decrease, but not increase. */ |
2003 | BUG_ON(i >= group_size); | |
134d3373 TH |
2004 | ent.task = tsk; |
2005 | ent.cgrp = task_cgroup_from_root(tsk, root); | |
892a2b90 MSB |
2006 | /* nothing to do if this task is already in the cgroup */ |
2007 | if (ent.cgrp == cgrp) | |
2008 | continue; | |
61d1d219 MSB |
2009 | /* |
2010 | * saying GFP_ATOMIC has no effect here because we did prealloc | |
2011 | * earlier, but it's good form to communicate our expectations. | |
2012 | */ | |
134d3373 | 2013 | retval = flex_array_put(group, i, &ent, GFP_ATOMIC); |
d846687d | 2014 | BUG_ON(retval != 0); |
74a1166d | 2015 | i++; |
081aa458 LZ |
2016 | |
2017 | if (!threadgroup) | |
2018 | break; | |
74a1166d | 2019 | } while_each_thread(leader, tsk); |
fb5d2b4c | 2020 | rcu_read_unlock(); |
74a1166d BB |
2021 | /* remember the number of threads in the array for later. */ |
2022 | group_size = i; | |
2f7ee569 TH |
2023 | tset.tc_array = group; |
2024 | tset.tc_array_len = group_size; | |
74a1166d | 2025 | |
134d3373 TH |
2026 | /* methods shouldn't be called if no task is actually migrating */ |
2027 | retval = 0; | |
892a2b90 | 2028 | if (!group_size) |
b07ef774 | 2029 | goto out_free_group_list; |
134d3373 | 2030 | |
74a1166d BB |
2031 | /* |
2032 | * step 1: check that we can legitimately attach to the cgroup. | |
2033 | */ | |
2034 | for_each_subsys(root, ss) { | |
2035 | if (ss->can_attach) { | |
761b3ef5 | 2036 | retval = ss->can_attach(cgrp, &tset); |
74a1166d BB |
2037 | if (retval) { |
2038 | failed_ss = ss; | |
2039 | goto out_cancel_attach; | |
2040 | } | |
2041 | } | |
74a1166d BB |
2042 | } |
2043 | ||
2044 | /* | |
2045 | * step 2: make sure css_sets exist for all threads to be migrated. | |
2046 | * we use find_css_set, which allocates a new one if necessary. | |
2047 | */ | |
74a1166d | 2048 | for (i = 0; i < group_size; i++) { |
134d3373 | 2049 | tc = flex_array_get(group, i); |
61d1d219 MSB |
2050 | tc->cg = find_css_set(tc->task->cgroups, cgrp); |
2051 | if (!tc->cg) { | |
2052 | retval = -ENOMEM; | |
2053 | goto out_put_css_set_refs; | |
74a1166d BB |
2054 | } |
2055 | } | |
2056 | ||
2057 | /* | |
494c167c TH |
2058 | * step 3: now that we're guaranteed success wrt the css_sets, |
2059 | * proceed to move all tasks to the new cgroup. There are no | |
2060 | * failure cases after here, so this is the commit point. | |
74a1166d | 2061 | */ |
74a1166d | 2062 | for (i = 0; i < group_size; i++) { |
134d3373 | 2063 | tc = flex_array_get(group, i); |
1e2ccd1c | 2064 | cgroup_task_migrate(tc->cgrp, tc->task, tc->cg); |
74a1166d BB |
2065 | } |
2066 | /* nothing is sensitive to fork() after this point. */ | |
2067 | ||
2068 | /* | |
494c167c | 2069 | * step 4: do subsystem attach callbacks. |
74a1166d BB |
2070 | */ |
2071 | for_each_subsys(root, ss) { | |
2072 | if (ss->attach) | |
761b3ef5 | 2073 | ss->attach(cgrp, &tset); |
74a1166d BB |
2074 | } |
2075 | ||
2076 | /* | |
2077 | * step 5: success! and cleanup | |
2078 | */ | |
74a1166d | 2079 | retval = 0; |
61d1d219 MSB |
2080 | out_put_css_set_refs: |
2081 | if (retval) { | |
2082 | for (i = 0; i < group_size; i++) { | |
2083 | tc = flex_array_get(group, i); | |
2084 | if (!tc->cg) | |
2085 | break; | |
2086 | put_css_set(tc->cg); | |
2087 | } | |
74a1166d BB |
2088 | } |
2089 | out_cancel_attach: | |
74a1166d BB |
2090 | if (retval) { |
2091 | for_each_subsys(root, ss) { | |
494c167c | 2092 | if (ss == failed_ss) |
74a1166d | 2093 | break; |
74a1166d | 2094 | if (ss->cancel_attach) |
761b3ef5 | 2095 | ss->cancel_attach(cgrp, &tset); |
74a1166d BB |
2096 | } |
2097 | } | |
74a1166d | 2098 | out_free_group_list: |
d846687d | 2099 | flex_array_free(group); |
74a1166d BB |
2100 | return retval; |
2101 | } | |
2102 | ||
2103 | /* | |
2104 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 TH |
2105 | * function to attach either it or all tasks in its threadgroup. Will lock |
2106 | * cgroup_mutex and threadgroup; may take task_lock of task. | |
bbcb81d0 | 2107 | */ |
74a1166d | 2108 | static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) |
bbcb81d0 | 2109 | { |
bbcb81d0 | 2110 | struct task_struct *tsk; |
c69e8d9c | 2111 | const struct cred *cred = current_cred(), *tcred; |
bbcb81d0 PM |
2112 | int ret; |
2113 | ||
74a1166d BB |
2114 | if (!cgroup_lock_live_group(cgrp)) |
2115 | return -ENODEV; | |
2116 | ||
b78949eb MSB |
2117 | retry_find_task: |
2118 | rcu_read_lock(); | |
bbcb81d0 | 2119 | if (pid) { |
73507f33 | 2120 | tsk = find_task_by_vpid(pid); |
74a1166d BB |
2121 | if (!tsk) { |
2122 | rcu_read_unlock(); | |
b78949eb MSB |
2123 | ret= -ESRCH; |
2124 | goto out_unlock_cgroup; | |
bbcb81d0 | 2125 | } |
74a1166d BB |
2126 | /* |
2127 | * even if we're attaching all tasks in the thread group, we | |
2128 | * only need to check permissions on one of them. | |
2129 | */ | |
c69e8d9c | 2130 | tcred = __task_cred(tsk); |
14a590c3 EB |
2131 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
2132 | !uid_eq(cred->euid, tcred->uid) && | |
2133 | !uid_eq(cred->euid, tcred->suid)) { | |
c69e8d9c | 2134 | rcu_read_unlock(); |
b78949eb MSB |
2135 | ret = -EACCES; |
2136 | goto out_unlock_cgroup; | |
bbcb81d0 | 2137 | } |
b78949eb MSB |
2138 | } else |
2139 | tsk = current; | |
cd3d0952 TH |
2140 | |
2141 | if (threadgroup) | |
b78949eb | 2142 | tsk = tsk->group_leader; |
c4c27fbd MG |
2143 | |
2144 | /* | |
14a40ffc | 2145 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2146 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2147 | * with no rt_runtime allocated. Just say no. | |
2148 | */ | |
14a40ffc | 2149 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd MG |
2150 | ret = -EINVAL; |
2151 | rcu_read_unlock(); | |
2152 | goto out_unlock_cgroup; | |
2153 | } | |
2154 | ||
b78949eb MSB |
2155 | get_task_struct(tsk); |
2156 | rcu_read_unlock(); | |
2157 | ||
2158 | threadgroup_lock(tsk); | |
2159 | if (threadgroup) { | |
2160 | if (!thread_group_leader(tsk)) { | |
2161 | /* | |
2162 | * a race with de_thread from another thread's exec() | |
2163 | * may strip us of our leadership, if this happens, | |
2164 | * there is no choice but to throw this task away and | |
2165 | * try again; this is | |
2166 | * "double-double-toil-and-trouble-check locking". | |
2167 | */ | |
2168 | threadgroup_unlock(tsk); | |
2169 | put_task_struct(tsk); | |
2170 | goto retry_find_task; | |
2171 | } | |
081aa458 LZ |
2172 | } |
2173 | ||
2174 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
2175 | ||
cd3d0952 TH |
2176 | threadgroup_unlock(tsk); |
2177 | ||
bbcb81d0 | 2178 | put_task_struct(tsk); |
b78949eb | 2179 | out_unlock_cgroup: |
47cfcd09 | 2180 | mutex_unlock(&cgroup_mutex); |
bbcb81d0 PM |
2181 | return ret; |
2182 | } | |
2183 | ||
7ae1bad9 TH |
2184 | /** |
2185 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2186 | * @from: attach to all cgroups of a given task | |
2187 | * @tsk: the task to be attached | |
2188 | */ | |
2189 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2190 | { | |
2191 | struct cgroupfs_root *root; | |
2192 | int retval = 0; | |
2193 | ||
47cfcd09 | 2194 | mutex_lock(&cgroup_mutex); |
7ae1bad9 TH |
2195 | for_each_active_root(root) { |
2196 | struct cgroup *from_cg = task_cgroup_from_root(from, root); | |
2197 | ||
2198 | retval = cgroup_attach_task(from_cg, tsk, false); | |
2199 | if (retval) | |
2200 | break; | |
2201 | } | |
47cfcd09 | 2202 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2203 | |
2204 | return retval; | |
2205 | } | |
2206 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2207 | ||
af351026 | 2208 | static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) |
74a1166d BB |
2209 | { |
2210 | return attach_task_by_pid(cgrp, pid, false); | |
2211 | } | |
2212 | ||
2213 | static int cgroup_procs_write(struct cgroup *cgrp, struct cftype *cft, u64 tgid) | |
af351026 | 2214 | { |
b78949eb | 2215 | return attach_task_by_pid(cgrp, tgid, true); |
af351026 PM |
2216 | } |
2217 | ||
e788e066 PM |
2218 | static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, |
2219 | const char *buffer) | |
2220 | { | |
2221 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); | |
f4a2589f EK |
2222 | if (strlen(buffer) >= PATH_MAX) |
2223 | return -EINVAL; | |
e788e066 PM |
2224 | if (!cgroup_lock_live_group(cgrp)) |
2225 | return -ENODEV; | |
e25e2cbb | 2226 | mutex_lock(&cgroup_root_mutex); |
e788e066 | 2227 | strcpy(cgrp->root->release_agent_path, buffer); |
e25e2cbb | 2228 | mutex_unlock(&cgroup_root_mutex); |
47cfcd09 | 2229 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2230 | return 0; |
2231 | } | |
2232 | ||
2233 | static int cgroup_release_agent_show(struct cgroup *cgrp, struct cftype *cft, | |
2234 | struct seq_file *seq) | |
2235 | { | |
2236 | if (!cgroup_lock_live_group(cgrp)) | |
2237 | return -ENODEV; | |
2238 | seq_puts(seq, cgrp->root->release_agent_path); | |
2239 | seq_putc(seq, '\n'); | |
47cfcd09 | 2240 | mutex_unlock(&cgroup_mutex); |
e788e066 PM |
2241 | return 0; |
2242 | } | |
2243 | ||
873fe09e TH |
2244 | static int cgroup_sane_behavior_show(struct cgroup *cgrp, struct cftype *cft, |
2245 | struct seq_file *seq) | |
2246 | { | |
2247 | seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp)); | |
e788e066 PM |
2248 | return 0; |
2249 | } | |
2250 | ||
84eea842 PM |
2251 | /* A buffer size big enough for numbers or short strings */ |
2252 | #define CGROUP_LOCAL_BUFFER_SIZE 64 | |
2253 | ||
e73d2c61 | 2254 | static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft, |
f4c753b7 PM |
2255 | struct file *file, |
2256 | const char __user *userbuf, | |
2257 | size_t nbytes, loff_t *unused_ppos) | |
355e0c48 | 2258 | { |
84eea842 | 2259 | char buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
355e0c48 | 2260 | int retval = 0; |
355e0c48 PM |
2261 | char *end; |
2262 | ||
2263 | if (!nbytes) | |
2264 | return -EINVAL; | |
2265 | if (nbytes >= sizeof(buffer)) | |
2266 | return -E2BIG; | |
2267 | if (copy_from_user(buffer, userbuf, nbytes)) | |
2268 | return -EFAULT; | |
2269 | ||
2270 | buffer[nbytes] = 0; /* nul-terminate */ | |
e73d2c61 | 2271 | if (cft->write_u64) { |
478988d3 | 2272 | u64 val = simple_strtoull(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2273 | if (*end) |
2274 | return -EINVAL; | |
2275 | retval = cft->write_u64(cgrp, cft, val); | |
2276 | } else { | |
478988d3 | 2277 | s64 val = simple_strtoll(strstrip(buffer), &end, 0); |
e73d2c61 PM |
2278 | if (*end) |
2279 | return -EINVAL; | |
2280 | retval = cft->write_s64(cgrp, cft, val); | |
2281 | } | |
355e0c48 PM |
2282 | if (!retval) |
2283 | retval = nbytes; | |
2284 | return retval; | |
2285 | } | |
2286 | ||
db3b1497 PM |
2287 | static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft, |
2288 | struct file *file, | |
2289 | const char __user *userbuf, | |
2290 | size_t nbytes, loff_t *unused_ppos) | |
2291 | { | |
84eea842 | 2292 | char local_buffer[CGROUP_LOCAL_BUFFER_SIZE]; |
db3b1497 PM |
2293 | int retval = 0; |
2294 | size_t max_bytes = cft->max_write_len; | |
2295 | char *buffer = local_buffer; | |
2296 | ||
2297 | if (!max_bytes) | |
2298 | max_bytes = sizeof(local_buffer) - 1; | |
2299 | if (nbytes >= max_bytes) | |
2300 | return -E2BIG; | |
2301 | /* Allocate a dynamic buffer if we need one */ | |
2302 | if (nbytes >= sizeof(local_buffer)) { | |
2303 | buffer = kmalloc(nbytes + 1, GFP_KERNEL); | |
2304 | if (buffer == NULL) | |
2305 | return -ENOMEM; | |
2306 | } | |
5a3eb9f6 LZ |
2307 | if (nbytes && copy_from_user(buffer, userbuf, nbytes)) { |
2308 | retval = -EFAULT; | |
2309 | goto out; | |
2310 | } | |
db3b1497 PM |
2311 | |
2312 | buffer[nbytes] = 0; /* nul-terminate */ | |
478988d3 | 2313 | retval = cft->write_string(cgrp, cft, strstrip(buffer)); |
db3b1497 PM |
2314 | if (!retval) |
2315 | retval = nbytes; | |
5a3eb9f6 | 2316 | out: |
db3b1497 PM |
2317 | if (buffer != local_buffer) |
2318 | kfree(buffer); | |
2319 | return retval; | |
2320 | } | |
2321 | ||
ddbcc7e8 PM |
2322 | static ssize_t cgroup_file_write(struct file *file, const char __user *buf, |
2323 | size_t nbytes, loff_t *ppos) | |
2324 | { | |
2325 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2326 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2327 | |
75139b82 | 2328 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 | 2329 | return -ENODEV; |
355e0c48 | 2330 | if (cft->write) |
bd89aabc | 2331 | return cft->write(cgrp, cft, file, buf, nbytes, ppos); |
e73d2c61 PM |
2332 | if (cft->write_u64 || cft->write_s64) |
2333 | return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos); | |
db3b1497 PM |
2334 | if (cft->write_string) |
2335 | return cgroup_write_string(cgrp, cft, file, buf, nbytes, ppos); | |
d447ea2f PE |
2336 | if (cft->trigger) { |
2337 | int ret = cft->trigger(cgrp, (unsigned int)cft->private); | |
2338 | return ret ? ret : nbytes; | |
2339 | } | |
355e0c48 | 2340 | return -EINVAL; |
ddbcc7e8 PM |
2341 | } |
2342 | ||
f4c753b7 PM |
2343 | static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, |
2344 | struct file *file, | |
2345 | char __user *buf, size_t nbytes, | |
2346 | loff_t *ppos) | |
ddbcc7e8 | 2347 | { |
84eea842 | 2348 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
f4c753b7 | 2349 | u64 val = cft->read_u64(cgrp, cft); |
ddbcc7e8 PM |
2350 | int len = sprintf(tmp, "%llu\n", (unsigned long long) val); |
2351 | ||
2352 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2353 | } | |
2354 | ||
e73d2c61 PM |
2355 | static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft, |
2356 | struct file *file, | |
2357 | char __user *buf, size_t nbytes, | |
2358 | loff_t *ppos) | |
2359 | { | |
84eea842 | 2360 | char tmp[CGROUP_LOCAL_BUFFER_SIZE]; |
e73d2c61 PM |
2361 | s64 val = cft->read_s64(cgrp, cft); |
2362 | int len = sprintf(tmp, "%lld\n", (long long) val); | |
2363 | ||
2364 | return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); | |
2365 | } | |
2366 | ||
ddbcc7e8 PM |
2367 | static ssize_t cgroup_file_read(struct file *file, char __user *buf, |
2368 | size_t nbytes, loff_t *ppos) | |
2369 | { | |
2370 | struct cftype *cft = __d_cft(file->f_dentry); | |
bd89aabc | 2371 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
ddbcc7e8 | 2372 | |
75139b82 | 2373 | if (cgroup_is_removed(cgrp)) |
ddbcc7e8 PM |
2374 | return -ENODEV; |
2375 | ||
2376 | if (cft->read) | |
bd89aabc | 2377 | return cft->read(cgrp, cft, file, buf, nbytes, ppos); |
f4c753b7 PM |
2378 | if (cft->read_u64) |
2379 | return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos); | |
e73d2c61 PM |
2380 | if (cft->read_s64) |
2381 | return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos); | |
ddbcc7e8 PM |
2382 | return -EINVAL; |
2383 | } | |
2384 | ||
91796569 PM |
2385 | /* |
2386 | * seqfile ops/methods for returning structured data. Currently just | |
2387 | * supports string->u64 maps, but can be extended in future. | |
2388 | */ | |
2389 | ||
2390 | struct cgroup_seqfile_state { | |
2391 | struct cftype *cft; | |
2392 | struct cgroup *cgroup; | |
2393 | }; | |
2394 | ||
2395 | static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) | |
2396 | { | |
2397 | struct seq_file *sf = cb->state; | |
2398 | return seq_printf(sf, "%s %llu\n", key, (unsigned long long)value); | |
2399 | } | |
2400 | ||
2401 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) | |
2402 | { | |
2403 | struct cgroup_seqfile_state *state = m->private; | |
2404 | struct cftype *cft = state->cft; | |
29486df3 SH |
2405 | if (cft->read_map) { |
2406 | struct cgroup_map_cb cb = { | |
2407 | .fill = cgroup_map_add, | |
2408 | .state = m, | |
2409 | }; | |
2410 | return cft->read_map(state->cgroup, cft, &cb); | |
2411 | } | |
2412 | return cft->read_seq_string(state->cgroup, cft, m); | |
91796569 PM |
2413 | } |
2414 | ||
96930a63 | 2415 | static int cgroup_seqfile_release(struct inode *inode, struct file *file) |
91796569 PM |
2416 | { |
2417 | struct seq_file *seq = file->private_data; | |
2418 | kfree(seq->private); | |
2419 | return single_release(inode, file); | |
2420 | } | |
2421 | ||
828c0950 | 2422 | static const struct file_operations cgroup_seqfile_operations = { |
91796569 | 2423 | .read = seq_read, |
e788e066 | 2424 | .write = cgroup_file_write, |
91796569 PM |
2425 | .llseek = seq_lseek, |
2426 | .release = cgroup_seqfile_release, | |
2427 | }; | |
2428 | ||
ddbcc7e8 PM |
2429 | static int cgroup_file_open(struct inode *inode, struct file *file) |
2430 | { | |
2431 | int err; | |
2432 | struct cftype *cft; | |
2433 | ||
2434 | err = generic_file_open(inode, file); | |
2435 | if (err) | |
2436 | return err; | |
ddbcc7e8 | 2437 | cft = __d_cft(file->f_dentry); |
75139b82 | 2438 | |
29486df3 | 2439 | if (cft->read_map || cft->read_seq_string) { |
91796569 PM |
2440 | struct cgroup_seqfile_state *state = |
2441 | kzalloc(sizeof(*state), GFP_USER); | |
2442 | if (!state) | |
2443 | return -ENOMEM; | |
2444 | state->cft = cft; | |
2445 | state->cgroup = __d_cgrp(file->f_dentry->d_parent); | |
2446 | file->f_op = &cgroup_seqfile_operations; | |
2447 | err = single_open(file, cgroup_seqfile_show, state); | |
2448 | if (err < 0) | |
2449 | kfree(state); | |
2450 | } else if (cft->open) | |
ddbcc7e8 PM |
2451 | err = cft->open(inode, file); |
2452 | else | |
2453 | err = 0; | |
2454 | ||
2455 | return err; | |
2456 | } | |
2457 | ||
2458 | static int cgroup_file_release(struct inode *inode, struct file *file) | |
2459 | { | |
2460 | struct cftype *cft = __d_cft(file->f_dentry); | |
2461 | if (cft->release) | |
2462 | return cft->release(inode, file); | |
2463 | return 0; | |
2464 | } | |
2465 | ||
2466 | /* | |
2467 | * cgroup_rename - Only allow simple rename of directories in place. | |
2468 | */ | |
2469 | static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2470 | struct inode *new_dir, struct dentry *new_dentry) | |
2471 | { | |
65dff759 LZ |
2472 | int ret; |
2473 | struct cgroup_name *name, *old_name; | |
2474 | struct cgroup *cgrp; | |
2475 | ||
2476 | /* | |
2477 | * It's convinient to use parent dir's i_mutex to protected | |
2478 | * cgrp->name. | |
2479 | */ | |
2480 | lockdep_assert_held(&old_dir->i_mutex); | |
2481 | ||
ddbcc7e8 PM |
2482 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) |
2483 | return -ENOTDIR; | |
2484 | if (new_dentry->d_inode) | |
2485 | return -EEXIST; | |
2486 | if (old_dir != new_dir) | |
2487 | return -EIO; | |
65dff759 LZ |
2488 | |
2489 | cgrp = __d_cgrp(old_dentry); | |
2490 | ||
2491 | name = cgroup_alloc_name(new_dentry); | |
2492 | if (!name) | |
2493 | return -ENOMEM; | |
2494 | ||
2495 | ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2496 | if (ret) { | |
2497 | kfree(name); | |
2498 | return ret; | |
2499 | } | |
2500 | ||
2501 | old_name = cgrp->name; | |
2502 | rcu_assign_pointer(cgrp->name, name); | |
2503 | ||
2504 | kfree_rcu(old_name, rcu_head); | |
2505 | return 0; | |
ddbcc7e8 PM |
2506 | } |
2507 | ||
03b1cde6 AR |
2508 | static struct simple_xattrs *__d_xattrs(struct dentry *dentry) |
2509 | { | |
2510 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
2511 | return &__d_cgrp(dentry)->xattrs; | |
2512 | else | |
712317ad | 2513 | return &__d_cfe(dentry)->xattrs; |
03b1cde6 AR |
2514 | } |
2515 | ||
2516 | static inline int xattr_enabled(struct dentry *dentry) | |
2517 | { | |
2518 | struct cgroupfs_root *root = dentry->d_sb->s_fs_info; | |
93438629 | 2519 | return root->flags & CGRP_ROOT_XATTR; |
03b1cde6 AR |
2520 | } |
2521 | ||
2522 | static bool is_valid_xattr(const char *name) | |
2523 | { | |
2524 | if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || | |
2525 | !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) | |
2526 | return true; | |
2527 | return false; | |
2528 | } | |
2529 | ||
2530 | static int cgroup_setxattr(struct dentry *dentry, const char *name, | |
2531 | const void *val, size_t size, int flags) | |
2532 | { | |
2533 | if (!xattr_enabled(dentry)) | |
2534 | return -EOPNOTSUPP; | |
2535 | if (!is_valid_xattr(name)) | |
2536 | return -EINVAL; | |
2537 | return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); | |
2538 | } | |
2539 | ||
2540 | static int cgroup_removexattr(struct dentry *dentry, const char *name) | |
2541 | { | |
2542 | if (!xattr_enabled(dentry)) | |
2543 | return -EOPNOTSUPP; | |
2544 | if (!is_valid_xattr(name)) | |
2545 | return -EINVAL; | |
2546 | return simple_xattr_remove(__d_xattrs(dentry), name); | |
2547 | } | |
2548 | ||
2549 | static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, | |
2550 | void *buf, size_t size) | |
2551 | { | |
2552 | if (!xattr_enabled(dentry)) | |
2553 | return -EOPNOTSUPP; | |
2554 | if (!is_valid_xattr(name)) | |
2555 | return -EINVAL; | |
2556 | return simple_xattr_get(__d_xattrs(dentry), name, buf, size); | |
2557 | } | |
2558 | ||
2559 | static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) | |
2560 | { | |
2561 | if (!xattr_enabled(dentry)) | |
2562 | return -EOPNOTSUPP; | |
2563 | return simple_xattr_list(__d_xattrs(dentry), buf, size); | |
2564 | } | |
2565 | ||
828c0950 | 2566 | static const struct file_operations cgroup_file_operations = { |
ddbcc7e8 PM |
2567 | .read = cgroup_file_read, |
2568 | .write = cgroup_file_write, | |
2569 | .llseek = generic_file_llseek, | |
2570 | .open = cgroup_file_open, | |
2571 | .release = cgroup_file_release, | |
2572 | }; | |
2573 | ||
03b1cde6 AR |
2574 | static const struct inode_operations cgroup_file_inode_operations = { |
2575 | .setxattr = cgroup_setxattr, | |
2576 | .getxattr = cgroup_getxattr, | |
2577 | .listxattr = cgroup_listxattr, | |
2578 | .removexattr = cgroup_removexattr, | |
2579 | }; | |
2580 | ||
6e1d5dcc | 2581 | static const struct inode_operations cgroup_dir_inode_operations = { |
c72a04e3 | 2582 | .lookup = cgroup_lookup, |
ddbcc7e8 PM |
2583 | .mkdir = cgroup_mkdir, |
2584 | .rmdir = cgroup_rmdir, | |
2585 | .rename = cgroup_rename, | |
03b1cde6 AR |
2586 | .setxattr = cgroup_setxattr, |
2587 | .getxattr = cgroup_getxattr, | |
2588 | .listxattr = cgroup_listxattr, | |
2589 | .removexattr = cgroup_removexattr, | |
ddbcc7e8 PM |
2590 | }; |
2591 | ||
00cd8dd3 | 2592 | static struct dentry *cgroup_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
c72a04e3 AV |
2593 | { |
2594 | if (dentry->d_name.len > NAME_MAX) | |
2595 | return ERR_PTR(-ENAMETOOLONG); | |
2596 | d_add(dentry, NULL); | |
2597 | return NULL; | |
2598 | } | |
2599 | ||
0dea1168 KS |
2600 | /* |
2601 | * Check if a file is a control file | |
2602 | */ | |
2603 | static inline struct cftype *__file_cft(struct file *file) | |
2604 | { | |
496ad9aa | 2605 | if (file_inode(file)->i_fop != &cgroup_file_operations) |
0dea1168 KS |
2606 | return ERR_PTR(-EINVAL); |
2607 | return __d_cft(file->f_dentry); | |
2608 | } | |
2609 | ||
a5e7ed32 | 2610 | static int cgroup_create_file(struct dentry *dentry, umode_t mode, |
5adcee1d NP |
2611 | struct super_block *sb) |
2612 | { | |
ddbcc7e8 PM |
2613 | struct inode *inode; |
2614 | ||
2615 | if (!dentry) | |
2616 | return -ENOENT; | |
2617 | if (dentry->d_inode) | |
2618 | return -EEXIST; | |
2619 | ||
2620 | inode = cgroup_new_inode(mode, sb); | |
2621 | if (!inode) | |
2622 | return -ENOMEM; | |
2623 | ||
2624 | if (S_ISDIR(mode)) { | |
2625 | inode->i_op = &cgroup_dir_inode_operations; | |
2626 | inode->i_fop = &simple_dir_operations; | |
2627 | ||
2628 | /* start off with i_nlink == 2 (for "." entry) */ | |
2629 | inc_nlink(inode); | |
28fd6f30 | 2630 | inc_nlink(dentry->d_parent->d_inode); |
ddbcc7e8 | 2631 | |
b8a2df6a TH |
2632 | /* |
2633 | * Control reaches here with cgroup_mutex held. | |
2634 | * @inode->i_mutex should nest outside cgroup_mutex but we | |
2635 | * want to populate it immediately without releasing | |
2636 | * cgroup_mutex. As @inode isn't visible to anyone else | |
2637 | * yet, trylock will always succeed without affecting | |
2638 | * lockdep checks. | |
2639 | */ | |
2640 | WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex)); | |
ddbcc7e8 PM |
2641 | } else if (S_ISREG(mode)) { |
2642 | inode->i_size = 0; | |
2643 | inode->i_fop = &cgroup_file_operations; | |
03b1cde6 | 2644 | inode->i_op = &cgroup_file_inode_operations; |
ddbcc7e8 | 2645 | } |
ddbcc7e8 PM |
2646 | d_instantiate(dentry, inode); |
2647 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2648 | return 0; | |
2649 | } | |
2650 | ||
099fca32 LZ |
2651 | /** |
2652 | * cgroup_file_mode - deduce file mode of a control file | |
2653 | * @cft: the control file in question | |
2654 | * | |
2655 | * returns cft->mode if ->mode is not 0 | |
2656 | * returns S_IRUGO|S_IWUSR if it has both a read and a write handler | |
2657 | * returns S_IRUGO if it has only a read handler | |
2658 | * returns S_IWUSR if it has only a write hander | |
2659 | */ | |
a5e7ed32 | 2660 | static umode_t cgroup_file_mode(const struct cftype *cft) |
099fca32 | 2661 | { |
a5e7ed32 | 2662 | umode_t mode = 0; |
099fca32 LZ |
2663 | |
2664 | if (cft->mode) | |
2665 | return cft->mode; | |
2666 | ||
2667 | if (cft->read || cft->read_u64 || cft->read_s64 || | |
2668 | cft->read_map || cft->read_seq_string) | |
2669 | mode |= S_IRUGO; | |
2670 | ||
2671 | if (cft->write || cft->write_u64 || cft->write_s64 || | |
2672 | cft->write_string || cft->trigger) | |
2673 | mode |= S_IWUSR; | |
2674 | ||
2675 | return mode; | |
2676 | } | |
2677 | ||
db0416b6 | 2678 | static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
03b1cde6 | 2679 | struct cftype *cft) |
ddbcc7e8 | 2680 | { |
bd89aabc | 2681 | struct dentry *dir = cgrp->dentry; |
05ef1d7c | 2682 | struct cgroup *parent = __d_cgrp(dir); |
ddbcc7e8 | 2683 | struct dentry *dentry; |
05ef1d7c | 2684 | struct cfent *cfe; |
ddbcc7e8 | 2685 | int error; |
a5e7ed32 | 2686 | umode_t mode; |
ddbcc7e8 | 2687 | char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; |
8e3f6541 | 2688 | |
93438629 | 2689 | if (subsys && !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { |
ddbcc7e8 PM |
2690 | strcpy(name, subsys->name); |
2691 | strcat(name, "."); | |
2692 | } | |
2693 | strcat(name, cft->name); | |
05ef1d7c | 2694 | |
ddbcc7e8 | 2695 | BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); |
05ef1d7c TH |
2696 | |
2697 | cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); | |
2698 | if (!cfe) | |
2699 | return -ENOMEM; | |
2700 | ||
ddbcc7e8 | 2701 | dentry = lookup_one_len(name, dir, strlen(name)); |
05ef1d7c | 2702 | if (IS_ERR(dentry)) { |
ddbcc7e8 | 2703 | error = PTR_ERR(dentry); |
05ef1d7c TH |
2704 | goto out; |
2705 | } | |
2706 | ||
2707 | mode = cgroup_file_mode(cft); | |
2708 | error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); | |
2709 | if (!error) { | |
2710 | cfe->type = (void *)cft; | |
2711 | cfe->dentry = dentry; | |
2712 | dentry->d_fsdata = cfe; | |
712317ad | 2713 | simple_xattrs_init(&cfe->xattrs); |
05ef1d7c TH |
2714 | list_add_tail(&cfe->node, &parent->files); |
2715 | cfe = NULL; | |
2716 | } | |
2717 | dput(dentry); | |
2718 | out: | |
2719 | kfree(cfe); | |
ddbcc7e8 PM |
2720 | return error; |
2721 | } | |
2722 | ||
79578621 | 2723 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys, |
03b1cde6 | 2724 | struct cftype cfts[], bool is_add) |
ddbcc7e8 | 2725 | { |
03b1cde6 | 2726 | struct cftype *cft; |
db0416b6 TH |
2727 | int err, ret = 0; |
2728 | ||
2729 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 2730 | /* does cft->flags tell us to skip this file on @cgrp? */ |
873fe09e TH |
2731 | if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp)) |
2732 | continue; | |
f33fddc2 G |
2733 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) |
2734 | continue; | |
2735 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) | |
2736 | continue; | |
2737 | ||
2739d3cc | 2738 | if (is_add) { |
79578621 | 2739 | err = cgroup_add_file(cgrp, subsys, cft); |
2739d3cc LZ |
2740 | if (err) |
2741 | pr_warn("cgroup_addrm_files: failed to add %s, err=%d\n", | |
2742 | cft->name, err); | |
db0416b6 | 2743 | ret = err; |
2739d3cc LZ |
2744 | } else { |
2745 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 2746 | } |
ddbcc7e8 | 2747 | } |
db0416b6 | 2748 | return ret; |
ddbcc7e8 PM |
2749 | } |
2750 | ||
8e3f6541 TH |
2751 | static DEFINE_MUTEX(cgroup_cft_mutex); |
2752 | ||
2753 | static void cgroup_cfts_prepare(void) | |
2754 | __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex) | |
2755 | { | |
2756 | /* | |
2757 | * Thanks to the entanglement with vfs inode locking, we can't walk | |
2758 | * the existing cgroups under cgroup_mutex and create files. | |
2759 | * Instead, we increment reference on all cgroups and build list of | |
2760 | * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure | |
2761 | * exclusive access to the field. | |
2762 | */ | |
2763 | mutex_lock(&cgroup_cft_mutex); | |
2764 | mutex_lock(&cgroup_mutex); | |
2765 | } | |
2766 | ||
2767 | static void cgroup_cfts_commit(struct cgroup_subsys *ss, | |
03b1cde6 | 2768 | struct cftype *cfts, bool is_add) |
8e3f6541 TH |
2769 | __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex) |
2770 | { | |
2771 | LIST_HEAD(pending); | |
2772 | struct cgroup *cgrp, *n; | |
8e3f6541 TH |
2773 | |
2774 | /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ | |
2775 | if (cfts && ss->root != &rootnode) { | |
2776 | list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) { | |
2777 | dget(cgrp->dentry); | |
2778 | list_add_tail(&cgrp->cft_q_node, &pending); | |
2779 | } | |
2780 | } | |
2781 | ||
2782 | mutex_unlock(&cgroup_mutex); | |
2783 | ||
2784 | /* | |
2785 | * All new cgroups will see @cfts update on @ss->cftsets. Add/rm | |
2786 | * files for all cgroups which were created before. | |
2787 | */ | |
2788 | list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) { | |
2789 | struct inode *inode = cgrp->dentry->d_inode; | |
2790 | ||
2791 | mutex_lock(&inode->i_mutex); | |
2792 | mutex_lock(&cgroup_mutex); | |
2793 | if (!cgroup_is_removed(cgrp)) | |
79578621 | 2794 | cgroup_addrm_files(cgrp, ss, cfts, is_add); |
8e3f6541 TH |
2795 | mutex_unlock(&cgroup_mutex); |
2796 | mutex_unlock(&inode->i_mutex); | |
2797 | ||
2798 | list_del_init(&cgrp->cft_q_node); | |
2799 | dput(cgrp->dentry); | |
2800 | } | |
2801 | ||
2802 | mutex_unlock(&cgroup_cft_mutex); | |
2803 | } | |
2804 | ||
2805 | /** | |
2806 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
2807 | * @ss: target cgroup subsystem | |
2808 | * @cfts: zero-length name terminated array of cftypes | |
2809 | * | |
2810 | * Register @cfts to @ss. Files described by @cfts are created for all | |
2811 | * existing cgroups to which @ss is attached and all future cgroups will | |
2812 | * have them too. This function can be called anytime whether @ss is | |
2813 | * attached or not. | |
2814 | * | |
2815 | * Returns 0 on successful registration, -errno on failure. Note that this | |
2816 | * function currently returns 0 as long as @cfts registration is successful | |
2817 | * even if some file creation attempts on existing cgroups fail. | |
2818 | */ | |
03b1cde6 | 2819 | int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 TH |
2820 | { |
2821 | struct cftype_set *set; | |
2822 | ||
2823 | set = kzalloc(sizeof(*set), GFP_KERNEL); | |
2824 | if (!set) | |
2825 | return -ENOMEM; | |
2826 | ||
2827 | cgroup_cfts_prepare(); | |
2828 | set->cfts = cfts; | |
2829 | list_add_tail(&set->node, &ss->cftsets); | |
79578621 | 2830 | cgroup_cfts_commit(ss, cfts, true); |
8e3f6541 TH |
2831 | |
2832 | return 0; | |
2833 | } | |
2834 | EXPORT_SYMBOL_GPL(cgroup_add_cftypes); | |
2835 | ||
79578621 TH |
2836 | /** |
2837 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
2838 | * @ss: target cgroup subsystem | |
2839 | * @cfts: zero-length name terminated array of cftypes | |
2840 | * | |
2841 | * Unregister @cfts from @ss. Files described by @cfts are removed from | |
2842 | * all existing cgroups to which @ss is attached and all future cgroups | |
2843 | * won't have them either. This function can be called anytime whether @ss | |
2844 | * is attached or not. | |
2845 | * | |
2846 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2847 | * registered with @ss. | |
2848 | */ | |
03b1cde6 | 2849 | int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
79578621 TH |
2850 | { |
2851 | struct cftype_set *set; | |
2852 | ||
2853 | cgroup_cfts_prepare(); | |
2854 | ||
2855 | list_for_each_entry(set, &ss->cftsets, node) { | |
2856 | if (set->cfts == cfts) { | |
2857 | list_del_init(&set->node); | |
2858 | cgroup_cfts_commit(ss, cfts, false); | |
2859 | return 0; | |
2860 | } | |
2861 | } | |
2862 | ||
2863 | cgroup_cfts_commit(ss, NULL, false); | |
2864 | return -ENOENT; | |
2865 | } | |
2866 | ||
a043e3b2 LZ |
2867 | /** |
2868 | * cgroup_task_count - count the number of tasks in a cgroup. | |
2869 | * @cgrp: the cgroup in question | |
2870 | * | |
2871 | * Return the number of tasks in the cgroup. | |
2872 | */ | |
bd89aabc | 2873 | int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
2874 | { |
2875 | int count = 0; | |
71cbb949 | 2876 | struct cg_cgroup_link *link; |
817929ec PM |
2877 | |
2878 | read_lock(&css_set_lock); | |
71cbb949 | 2879 | list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { |
146aa1bd | 2880 | count += atomic_read(&link->cg->refcount); |
817929ec PM |
2881 | } |
2882 | read_unlock(&css_set_lock); | |
bbcb81d0 PM |
2883 | return count; |
2884 | } | |
2885 | ||
817929ec PM |
2886 | /* |
2887 | * Advance a list_head iterator. The iterator should be positioned at | |
2888 | * the start of a css_set | |
2889 | */ | |
bd89aabc | 2890 | static void cgroup_advance_iter(struct cgroup *cgrp, |
7717f7ba | 2891 | struct cgroup_iter *it) |
817929ec PM |
2892 | { |
2893 | struct list_head *l = it->cg_link; | |
2894 | struct cg_cgroup_link *link; | |
2895 | struct css_set *cg; | |
2896 | ||
2897 | /* Advance to the next non-empty css_set */ | |
2898 | do { | |
2899 | l = l->next; | |
bd89aabc | 2900 | if (l == &cgrp->css_sets) { |
817929ec PM |
2901 | it->cg_link = NULL; |
2902 | return; | |
2903 | } | |
bd89aabc | 2904 | link = list_entry(l, struct cg_cgroup_link, cgrp_link_list); |
817929ec PM |
2905 | cg = link->cg; |
2906 | } while (list_empty(&cg->tasks)); | |
2907 | it->cg_link = l; | |
2908 | it->task = cg->tasks.next; | |
2909 | } | |
2910 | ||
31a7df01 CW |
2911 | /* |
2912 | * To reduce the fork() overhead for systems that are not actually | |
2913 | * using their cgroups capability, we don't maintain the lists running | |
2914 | * through each css_set to its tasks until we see the list actually | |
2915 | * used - in other words after the first call to cgroup_iter_start(). | |
31a7df01 | 2916 | */ |
3df91fe3 | 2917 | static void cgroup_enable_task_cg_lists(void) |
31a7df01 CW |
2918 | { |
2919 | struct task_struct *p, *g; | |
2920 | write_lock(&css_set_lock); | |
2921 | use_task_css_set_links = 1; | |
3ce3230a FW |
2922 | /* |
2923 | * We need tasklist_lock because RCU is not safe against | |
2924 | * while_each_thread(). Besides, a forking task that has passed | |
2925 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
2926 | * is not guaranteed to have its child immediately visible in the | |
2927 | * tasklist if we walk through it with RCU. | |
2928 | */ | |
2929 | read_lock(&tasklist_lock); | |
31a7df01 CW |
2930 | do_each_thread(g, p) { |
2931 | task_lock(p); | |
0e04388f LZ |
2932 | /* |
2933 | * We should check if the process is exiting, otherwise | |
2934 | * it will race with cgroup_exit() in that the list | |
2935 | * entry won't be deleted though the process has exited. | |
2936 | */ | |
2937 | if (!(p->flags & PF_EXITING) && list_empty(&p->cg_list)) | |
31a7df01 CW |
2938 | list_add(&p->cg_list, &p->cgroups->tasks); |
2939 | task_unlock(p); | |
2940 | } while_each_thread(g, p); | |
3ce3230a | 2941 | read_unlock(&tasklist_lock); |
31a7df01 CW |
2942 | write_unlock(&css_set_lock); |
2943 | } | |
2944 | ||
574bd9f7 TH |
2945 | /** |
2946 | * cgroup_next_descendant_pre - find the next descendant for pre-order walk | |
2947 | * @pos: the current position (%NULL to initiate traversal) | |
2948 | * @cgroup: cgroup whose descendants to walk | |
2949 | * | |
2950 | * To be used by cgroup_for_each_descendant_pre(). Find the next | |
2951 | * descendant to visit for pre-order traversal of @cgroup's descendants. | |
2952 | */ | |
2953 | struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, | |
2954 | struct cgroup *cgroup) | |
2955 | { | |
2956 | struct cgroup *next; | |
2957 | ||
2958 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
2959 | ||
2960 | /* if first iteration, pretend we just visited @cgroup */ | |
2961 | if (!pos) { | |
2962 | if (list_empty(&cgroup->children)) | |
2963 | return NULL; | |
2964 | pos = cgroup; | |
2965 | } | |
2966 | ||
2967 | /* visit the first child if exists */ | |
2968 | next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling); | |
2969 | if (next) | |
2970 | return next; | |
2971 | ||
2972 | /* no child, visit my or the closest ancestor's next sibling */ | |
2973 | do { | |
2974 | next = list_entry_rcu(pos->sibling.next, struct cgroup, | |
2975 | sibling); | |
2976 | if (&next->sibling != &pos->parent->children) | |
2977 | return next; | |
2978 | ||
2979 | pos = pos->parent; | |
2980 | } while (pos != cgroup); | |
2981 | ||
2982 | return NULL; | |
2983 | } | |
2984 | EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre); | |
2985 | ||
12a9d2fe TH |
2986 | /** |
2987 | * cgroup_rightmost_descendant - return the rightmost descendant of a cgroup | |
2988 | * @pos: cgroup of interest | |
2989 | * | |
2990 | * Return the rightmost descendant of @pos. If there's no descendant, | |
2991 | * @pos is returned. This can be used during pre-order traversal to skip | |
2992 | * subtree of @pos. | |
2993 | */ | |
2994 | struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos) | |
2995 | { | |
2996 | struct cgroup *last, *tmp; | |
2997 | ||
2998 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
2999 | ||
3000 | do { | |
3001 | last = pos; | |
3002 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3003 | pos = NULL; | |
3004 | list_for_each_entry_rcu(tmp, &last->children, sibling) | |
3005 | pos = tmp; | |
3006 | } while (pos); | |
3007 | ||
3008 | return last; | |
3009 | } | |
3010 | EXPORT_SYMBOL_GPL(cgroup_rightmost_descendant); | |
3011 | ||
574bd9f7 TH |
3012 | static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) |
3013 | { | |
3014 | struct cgroup *last; | |
3015 | ||
3016 | do { | |
3017 | last = pos; | |
3018 | pos = list_first_or_null_rcu(&pos->children, struct cgroup, | |
3019 | sibling); | |
3020 | } while (pos); | |
3021 | ||
3022 | return last; | |
3023 | } | |
3024 | ||
3025 | /** | |
3026 | * cgroup_next_descendant_post - find the next descendant for post-order walk | |
3027 | * @pos: the current position (%NULL to initiate traversal) | |
3028 | * @cgroup: cgroup whose descendants to walk | |
3029 | * | |
3030 | * To be used by cgroup_for_each_descendant_post(). Find the next | |
3031 | * descendant to visit for post-order traversal of @cgroup's descendants. | |
3032 | */ | |
3033 | struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, | |
3034 | struct cgroup *cgroup) | |
3035 | { | |
3036 | struct cgroup *next; | |
3037 | ||
3038 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
3039 | ||
3040 | /* if first iteration, visit the leftmost descendant */ | |
3041 | if (!pos) { | |
3042 | next = cgroup_leftmost_descendant(cgroup); | |
3043 | return next != cgroup ? next : NULL; | |
3044 | } | |
3045 | ||
3046 | /* if there's an unvisited sibling, visit its leftmost descendant */ | |
3047 | next = list_entry_rcu(pos->sibling.next, struct cgroup, sibling); | |
3048 | if (&next->sibling != &pos->parent->children) | |
3049 | return cgroup_leftmost_descendant(next); | |
3050 | ||
3051 | /* no sibling left, visit parent */ | |
3052 | next = pos->parent; | |
3053 | return next != cgroup ? next : NULL; | |
3054 | } | |
3055 | EXPORT_SYMBOL_GPL(cgroup_next_descendant_post); | |
3056 | ||
bd89aabc | 3057 | void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 3058 | __acquires(css_set_lock) |
817929ec PM |
3059 | { |
3060 | /* | |
3061 | * The first time anyone tries to iterate across a cgroup, | |
3062 | * we need to enable the list linking each css_set to its | |
3063 | * tasks, and fix up all existing tasks. | |
3064 | */ | |
31a7df01 CW |
3065 | if (!use_task_css_set_links) |
3066 | cgroup_enable_task_cg_lists(); | |
3067 | ||
817929ec | 3068 | read_lock(&css_set_lock); |
bd89aabc PM |
3069 | it->cg_link = &cgrp->css_sets; |
3070 | cgroup_advance_iter(cgrp, it); | |
817929ec PM |
3071 | } |
3072 | ||
bd89aabc | 3073 | struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
817929ec PM |
3074 | struct cgroup_iter *it) |
3075 | { | |
3076 | struct task_struct *res; | |
3077 | struct list_head *l = it->task; | |
2019f634 | 3078 | struct cg_cgroup_link *link; |
817929ec PM |
3079 | |
3080 | /* If the iterator cg is NULL, we have no tasks */ | |
3081 | if (!it->cg_link) | |
3082 | return NULL; | |
3083 | res = list_entry(l, struct task_struct, cg_list); | |
3084 | /* Advance iterator to find next entry */ | |
3085 | l = l->next; | |
2019f634 LJ |
3086 | link = list_entry(it->cg_link, struct cg_cgroup_link, cgrp_link_list); |
3087 | if (l == &link->cg->tasks) { | |
817929ec PM |
3088 | /* We reached the end of this task list - move on to |
3089 | * the next cg_cgroup_link */ | |
bd89aabc | 3090 | cgroup_advance_iter(cgrp, it); |
817929ec PM |
3091 | } else { |
3092 | it->task = l; | |
3093 | } | |
3094 | return res; | |
3095 | } | |
3096 | ||
bd89aabc | 3097 | void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it) |
c6ca5750 | 3098 | __releases(css_set_lock) |
817929ec PM |
3099 | { |
3100 | read_unlock(&css_set_lock); | |
3101 | } | |
3102 | ||
31a7df01 CW |
3103 | static inline int started_after_time(struct task_struct *t1, |
3104 | struct timespec *time, | |
3105 | struct task_struct *t2) | |
3106 | { | |
3107 | int start_diff = timespec_compare(&t1->start_time, time); | |
3108 | if (start_diff > 0) { | |
3109 | return 1; | |
3110 | } else if (start_diff < 0) { | |
3111 | return 0; | |
3112 | } else { | |
3113 | /* | |
3114 | * Arbitrarily, if two processes started at the same | |
3115 | * time, we'll say that the lower pointer value | |
3116 | * started first. Note that t2 may have exited by now | |
3117 | * so this may not be a valid pointer any longer, but | |
3118 | * that's fine - it still serves to distinguish | |
3119 | * between two tasks started (effectively) simultaneously. | |
3120 | */ | |
3121 | return t1 > t2; | |
3122 | } | |
3123 | } | |
3124 | ||
3125 | /* | |
3126 | * This function is a callback from heap_insert() and is used to order | |
3127 | * the heap. | |
3128 | * In this case we order the heap in descending task start time. | |
3129 | */ | |
3130 | static inline int started_after(void *p1, void *p2) | |
3131 | { | |
3132 | struct task_struct *t1 = p1; | |
3133 | struct task_struct *t2 = p2; | |
3134 | return started_after_time(t1, &t2->start_time, t2); | |
3135 | } | |
3136 | ||
3137 | /** | |
3138 | * cgroup_scan_tasks - iterate though all the tasks in a cgroup | |
3139 | * @scan: struct cgroup_scanner containing arguments for the scan | |
3140 | * | |
3141 | * Arguments include pointers to callback functions test_task() and | |
3142 | * process_task(). | |
3143 | * Iterate through all the tasks in a cgroup, calling test_task() for each, | |
3144 | * and if it returns true, call process_task() for it also. | |
3145 | * The test_task pointer may be NULL, meaning always true (select all tasks). | |
3146 | * Effectively duplicates cgroup_iter_{start,next,end}() | |
3147 | * but does not lock css_set_lock for the call to process_task(). | |
3148 | * The struct cgroup_scanner may be embedded in any structure of the caller's | |
3149 | * creation. | |
3150 | * It is guaranteed that process_task() will act on every task that | |
3151 | * is a member of the cgroup for the duration of this call. This | |
3152 | * function may or may not call process_task() for tasks that exit | |
3153 | * or move to a different cgroup during the call, or are forked or | |
3154 | * move into the cgroup during the call. | |
3155 | * | |
3156 | * Note that test_task() may be called with locks held, and may in some | |
3157 | * situations be called multiple times for the same task, so it should | |
3158 | * be cheap. | |
3159 | * If the heap pointer in the struct cgroup_scanner is non-NULL, a heap has been | |
3160 | * pre-allocated and will be used for heap operations (and its "gt" member will | |
3161 | * be overwritten), else a temporary heap will be used (allocation of which | |
3162 | * may cause this function to fail). | |
3163 | */ | |
3164 | int cgroup_scan_tasks(struct cgroup_scanner *scan) | |
3165 | { | |
3166 | int retval, i; | |
3167 | struct cgroup_iter it; | |
3168 | struct task_struct *p, *dropped; | |
3169 | /* Never dereference latest_task, since it's not refcounted */ | |
3170 | struct task_struct *latest_task = NULL; | |
3171 | struct ptr_heap tmp_heap; | |
3172 | struct ptr_heap *heap; | |
3173 | struct timespec latest_time = { 0, 0 }; | |
3174 | ||
3175 | if (scan->heap) { | |
3176 | /* The caller supplied our heap and pre-allocated its memory */ | |
3177 | heap = scan->heap; | |
3178 | heap->gt = &started_after; | |
3179 | } else { | |
3180 | /* We need to allocate our own heap memory */ | |
3181 | heap = &tmp_heap; | |
3182 | retval = heap_init(heap, PAGE_SIZE, GFP_KERNEL, &started_after); | |
3183 | if (retval) | |
3184 | /* cannot allocate the heap */ | |
3185 | return retval; | |
3186 | } | |
3187 | ||
3188 | again: | |
3189 | /* | |
3190 | * Scan tasks in the cgroup, using the scanner's "test_task" callback | |
3191 | * to determine which are of interest, and using the scanner's | |
3192 | * "process_task" callback to process any of them that need an update. | |
3193 | * Since we don't want to hold any locks during the task updates, | |
3194 | * gather tasks to be processed in a heap structure. | |
3195 | * The heap is sorted by descending task start time. | |
3196 | * If the statically-sized heap fills up, we overflow tasks that | |
3197 | * started later, and in future iterations only consider tasks that | |
3198 | * started after the latest task in the previous pass. This | |
3199 | * guarantees forward progress and that we don't miss any tasks. | |
3200 | */ | |
3201 | heap->size = 0; | |
3202 | cgroup_iter_start(scan->cg, &it); | |
3203 | while ((p = cgroup_iter_next(scan->cg, &it))) { | |
3204 | /* | |
3205 | * Only affect tasks that qualify per the caller's callback, | |
3206 | * if he provided one | |
3207 | */ | |
3208 | if (scan->test_task && !scan->test_task(p, scan)) | |
3209 | continue; | |
3210 | /* | |
3211 | * Only process tasks that started after the last task | |
3212 | * we processed | |
3213 | */ | |
3214 | if (!started_after_time(p, &latest_time, latest_task)) | |
3215 | continue; | |
3216 | dropped = heap_insert(heap, p); | |
3217 | if (dropped == NULL) { | |
3218 | /* | |
3219 | * The new task was inserted; the heap wasn't | |
3220 | * previously full | |
3221 | */ | |
3222 | get_task_struct(p); | |
3223 | } else if (dropped != p) { | |
3224 | /* | |
3225 | * The new task was inserted, and pushed out a | |
3226 | * different task | |
3227 | */ | |
3228 | get_task_struct(p); | |
3229 | put_task_struct(dropped); | |
3230 | } | |
3231 | /* | |
3232 | * Else the new task was newer than anything already in | |
3233 | * the heap and wasn't inserted | |
3234 | */ | |
3235 | } | |
3236 | cgroup_iter_end(scan->cg, &it); | |
3237 | ||
3238 | if (heap->size) { | |
3239 | for (i = 0; i < heap->size; i++) { | |
4fe91d51 | 3240 | struct task_struct *q = heap->ptrs[i]; |
31a7df01 | 3241 | if (i == 0) { |
4fe91d51 PJ |
3242 | latest_time = q->start_time; |
3243 | latest_task = q; | |
31a7df01 CW |
3244 | } |
3245 | /* Process the task per the caller's callback */ | |
4fe91d51 PJ |
3246 | scan->process_task(q, scan); |
3247 | put_task_struct(q); | |
31a7df01 CW |
3248 | } |
3249 | /* | |
3250 | * If we had to process any tasks at all, scan again | |
3251 | * in case some of them were in the middle of forking | |
3252 | * children that didn't get processed. | |
3253 | * Not the most efficient way to do it, but it avoids | |
3254 | * having to take callback_mutex in the fork path | |
3255 | */ | |
3256 | goto again; | |
3257 | } | |
3258 | if (heap == &tmp_heap) | |
3259 | heap_free(&tmp_heap); | |
3260 | return 0; | |
3261 | } | |
3262 | ||
8cc99345 TH |
3263 | static void cgroup_transfer_one_task(struct task_struct *task, |
3264 | struct cgroup_scanner *scan) | |
3265 | { | |
3266 | struct cgroup *new_cgroup = scan->data; | |
3267 | ||
47cfcd09 | 3268 | mutex_lock(&cgroup_mutex); |
8cc99345 | 3269 | cgroup_attach_task(new_cgroup, task, false); |
47cfcd09 | 3270 | mutex_unlock(&cgroup_mutex); |
8cc99345 TH |
3271 | } |
3272 | ||
3273 | /** | |
3274 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another | |
3275 | * @to: cgroup to which the tasks will be moved | |
3276 | * @from: cgroup in which the tasks currently reside | |
3277 | */ | |
3278 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) | |
3279 | { | |
3280 | struct cgroup_scanner scan; | |
3281 | ||
3282 | scan.cg = from; | |
3283 | scan.test_task = NULL; /* select all tasks in cgroup */ | |
3284 | scan.process_task = cgroup_transfer_one_task; | |
3285 | scan.heap = NULL; | |
3286 | scan.data = to; | |
3287 | ||
3288 | return cgroup_scan_tasks(&scan); | |
3289 | } | |
3290 | ||
bbcb81d0 | 3291 | /* |
102a775e | 3292 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3293 | * |
3294 | * Reading this file can return large amounts of data if a cgroup has | |
3295 | * *lots* of attached tasks. So it may need several calls to read(), | |
3296 | * but we cannot guarantee that the information we produce is correct | |
3297 | * unless we produce it entirely atomically. | |
3298 | * | |
bbcb81d0 | 3299 | */ |
bbcb81d0 | 3300 | |
24528255 LZ |
3301 | /* which pidlist file are we talking about? */ |
3302 | enum cgroup_filetype { | |
3303 | CGROUP_FILE_PROCS, | |
3304 | CGROUP_FILE_TASKS, | |
3305 | }; | |
3306 | ||
3307 | /* | |
3308 | * A pidlist is a list of pids that virtually represents the contents of one | |
3309 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3310 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3311 | * to the cgroup. | |
3312 | */ | |
3313 | struct cgroup_pidlist { | |
3314 | /* | |
3315 | * used to find which pidlist is wanted. doesn't change as long as | |
3316 | * this particular list stays in the list. | |
3317 | */ | |
3318 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3319 | /* array of xids */ | |
3320 | pid_t *list; | |
3321 | /* how many elements the above list has */ | |
3322 | int length; | |
3323 | /* how many files are using the current array */ | |
3324 | int use_count; | |
3325 | /* each of these stored in a list by its cgroup */ | |
3326 | struct list_head links; | |
3327 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3328 | struct cgroup *owner; | |
3329 | /* protects the other fields */ | |
3330 | struct rw_semaphore mutex; | |
3331 | }; | |
3332 | ||
d1d9fd33 BB |
3333 | /* |
3334 | * The following two functions "fix" the issue where there are more pids | |
3335 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3336 | * TODO: replace with a kernel-wide solution to this problem | |
3337 | */ | |
3338 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3339 | static void *pidlist_allocate(int count) | |
3340 | { | |
3341 | if (PIDLIST_TOO_LARGE(count)) | |
3342 | return vmalloc(count * sizeof(pid_t)); | |
3343 | else | |
3344 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3345 | } | |
3346 | static void pidlist_free(void *p) | |
3347 | { | |
3348 | if (is_vmalloc_addr(p)) | |
3349 | vfree(p); | |
3350 | else | |
3351 | kfree(p); | |
3352 | } | |
d1d9fd33 | 3353 | |
bbcb81d0 | 3354 | /* |
102a775e | 3355 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 3356 | * Returns the number of unique elements. |
bbcb81d0 | 3357 | */ |
6ee211ad | 3358 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 3359 | { |
102a775e | 3360 | int src, dest = 1; |
102a775e BB |
3361 | |
3362 | /* | |
3363 | * we presume the 0th element is unique, so i starts at 1. trivial | |
3364 | * edge cases first; no work needs to be done for either | |
3365 | */ | |
3366 | if (length == 0 || length == 1) | |
3367 | return length; | |
3368 | /* src and dest walk down the list; dest counts unique elements */ | |
3369 | for (src = 1; src < length; src++) { | |
3370 | /* find next unique element */ | |
3371 | while (list[src] == list[src-1]) { | |
3372 | src++; | |
3373 | if (src == length) | |
3374 | goto after; | |
3375 | } | |
3376 | /* dest always points to where the next unique element goes */ | |
3377 | list[dest] = list[src]; | |
3378 | dest++; | |
3379 | } | |
3380 | after: | |
102a775e BB |
3381 | return dest; |
3382 | } | |
3383 | ||
3384 | static int cmppid(const void *a, const void *b) | |
3385 | { | |
3386 | return *(pid_t *)a - *(pid_t *)b; | |
3387 | } | |
3388 | ||
72a8cb30 BB |
3389 | /* |
3390 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
3391 | * returns with the lock on that pidlist already held, and takes care | |
3392 | * of the use count, or returns NULL with no locks held if we're out of | |
3393 | * memory. | |
3394 | */ | |
3395 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, | |
3396 | enum cgroup_filetype type) | |
3397 | { | |
3398 | struct cgroup_pidlist *l; | |
3399 | /* don't need task_nsproxy() if we're looking at ourself */ | |
17cf22c3 | 3400 | struct pid_namespace *ns = task_active_pid_ns(current); |
b70cc5fd | 3401 | |
72a8cb30 BB |
3402 | /* |
3403 | * We can't drop the pidlist_mutex before taking the l->mutex in case | |
3404 | * the last ref-holder is trying to remove l from the list at the same | |
3405 | * time. Holding the pidlist_mutex precludes somebody taking whichever | |
3406 | * list we find out from under us - compare release_pid_array(). | |
3407 | */ | |
3408 | mutex_lock(&cgrp->pidlist_mutex); | |
3409 | list_for_each_entry(l, &cgrp->pidlists, links) { | |
3410 | if (l->key.type == type && l->key.ns == ns) { | |
72a8cb30 BB |
3411 | /* make sure l doesn't vanish out from under us */ |
3412 | down_write(&l->mutex); | |
3413 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3414 | return l; |
3415 | } | |
3416 | } | |
3417 | /* entry not found; create a new one */ | |
3418 | l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); | |
3419 | if (!l) { | |
3420 | mutex_unlock(&cgrp->pidlist_mutex); | |
72a8cb30 BB |
3421 | return l; |
3422 | } | |
3423 | init_rwsem(&l->mutex); | |
3424 | down_write(&l->mutex); | |
3425 | l->key.type = type; | |
b70cc5fd | 3426 | l->key.ns = get_pid_ns(ns); |
72a8cb30 BB |
3427 | l->use_count = 0; /* don't increment here */ |
3428 | l->list = NULL; | |
3429 | l->owner = cgrp; | |
3430 | list_add(&l->links, &cgrp->pidlists); | |
3431 | mutex_unlock(&cgrp->pidlist_mutex); | |
3432 | return l; | |
3433 | } | |
3434 | ||
102a775e BB |
3435 | /* |
3436 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
3437 | */ | |
72a8cb30 BB |
3438 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
3439 | struct cgroup_pidlist **lp) | |
102a775e BB |
3440 | { |
3441 | pid_t *array; | |
3442 | int length; | |
3443 | int pid, n = 0; /* used for populating the array */ | |
817929ec PM |
3444 | struct cgroup_iter it; |
3445 | struct task_struct *tsk; | |
102a775e BB |
3446 | struct cgroup_pidlist *l; |
3447 | ||
3448 | /* | |
3449 | * If cgroup gets more users after we read count, we won't have | |
3450 | * enough space - tough. This race is indistinguishable to the | |
3451 | * caller from the case that the additional cgroup users didn't | |
3452 | * show up until sometime later on. | |
3453 | */ | |
3454 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 3455 | array = pidlist_allocate(length); |
102a775e BB |
3456 | if (!array) |
3457 | return -ENOMEM; | |
3458 | /* now, populate the array */ | |
bd89aabc PM |
3459 | cgroup_iter_start(cgrp, &it); |
3460 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
102a775e | 3461 | if (unlikely(n == length)) |
817929ec | 3462 | break; |
102a775e | 3463 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
3464 | if (type == CGROUP_FILE_PROCS) |
3465 | pid = task_tgid_vnr(tsk); | |
3466 | else | |
3467 | pid = task_pid_vnr(tsk); | |
102a775e BB |
3468 | if (pid > 0) /* make sure to only use valid results */ |
3469 | array[n++] = pid; | |
817929ec | 3470 | } |
bd89aabc | 3471 | cgroup_iter_end(cgrp, &it); |
102a775e BB |
3472 | length = n; |
3473 | /* now sort & (if procs) strip out duplicates */ | |
3474 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 3475 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 3476 | length = pidlist_uniq(array, length); |
72a8cb30 BB |
3477 | l = cgroup_pidlist_find(cgrp, type); |
3478 | if (!l) { | |
d1d9fd33 | 3479 | pidlist_free(array); |
72a8cb30 | 3480 | return -ENOMEM; |
102a775e | 3481 | } |
72a8cb30 | 3482 | /* store array, freeing old if necessary - lock already held */ |
d1d9fd33 | 3483 | pidlist_free(l->list); |
102a775e BB |
3484 | l->list = array; |
3485 | l->length = length; | |
3486 | l->use_count++; | |
3487 | up_write(&l->mutex); | |
72a8cb30 | 3488 | *lp = l; |
102a775e | 3489 | return 0; |
bbcb81d0 PM |
3490 | } |
3491 | ||
846c7bb0 | 3492 | /** |
a043e3b2 | 3493 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
3494 | * @stats: cgroupstats to fill information into |
3495 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
3496 | * been requested. | |
a043e3b2 LZ |
3497 | * |
3498 | * Build and fill cgroupstats so that taskstats can export it to user | |
3499 | * space. | |
846c7bb0 BS |
3500 | */ |
3501 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
3502 | { | |
3503 | int ret = -EINVAL; | |
bd89aabc | 3504 | struct cgroup *cgrp; |
846c7bb0 BS |
3505 | struct cgroup_iter it; |
3506 | struct task_struct *tsk; | |
33d283be | 3507 | |
846c7bb0 | 3508 | /* |
33d283be LZ |
3509 | * Validate dentry by checking the superblock operations, |
3510 | * and make sure it's a directory. | |
846c7bb0 | 3511 | */ |
33d283be LZ |
3512 | if (dentry->d_sb->s_op != &cgroup_ops || |
3513 | !S_ISDIR(dentry->d_inode->i_mode)) | |
846c7bb0 BS |
3514 | goto err; |
3515 | ||
3516 | ret = 0; | |
bd89aabc | 3517 | cgrp = dentry->d_fsdata; |
846c7bb0 | 3518 | |
bd89aabc PM |
3519 | cgroup_iter_start(cgrp, &it); |
3520 | while ((tsk = cgroup_iter_next(cgrp, &it))) { | |
846c7bb0 BS |
3521 | switch (tsk->state) { |
3522 | case TASK_RUNNING: | |
3523 | stats->nr_running++; | |
3524 | break; | |
3525 | case TASK_INTERRUPTIBLE: | |
3526 | stats->nr_sleeping++; | |
3527 | break; | |
3528 | case TASK_UNINTERRUPTIBLE: | |
3529 | stats->nr_uninterruptible++; | |
3530 | break; | |
3531 | case TASK_STOPPED: | |
3532 | stats->nr_stopped++; | |
3533 | break; | |
3534 | default: | |
3535 | if (delayacct_is_task_waiting_on_io(tsk)) | |
3536 | stats->nr_io_wait++; | |
3537 | break; | |
3538 | } | |
3539 | } | |
bd89aabc | 3540 | cgroup_iter_end(cgrp, &it); |
846c7bb0 | 3541 | |
846c7bb0 BS |
3542 | err: |
3543 | return ret; | |
3544 | } | |
3545 | ||
8f3ff208 | 3546 | |
bbcb81d0 | 3547 | /* |
102a775e | 3548 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 3549 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 3550 | * in the cgroup->l->list array. |
bbcb81d0 | 3551 | */ |
cc31edce | 3552 | |
102a775e | 3553 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 3554 | { |
cc31edce PM |
3555 | /* |
3556 | * Initially we receive a position value that corresponds to | |
3557 | * one more than the last pid shown (or 0 on the first call or | |
3558 | * after a seek to the start). Use a binary-search to find the | |
3559 | * next pid to display, if any | |
3560 | */ | |
102a775e | 3561 | struct cgroup_pidlist *l = s->private; |
cc31edce PM |
3562 | int index = 0, pid = *pos; |
3563 | int *iter; | |
3564 | ||
102a775e | 3565 | down_read(&l->mutex); |
cc31edce | 3566 | if (pid) { |
102a775e | 3567 | int end = l->length; |
20777766 | 3568 | |
cc31edce PM |
3569 | while (index < end) { |
3570 | int mid = (index + end) / 2; | |
102a775e | 3571 | if (l->list[mid] == pid) { |
cc31edce PM |
3572 | index = mid; |
3573 | break; | |
102a775e | 3574 | } else if (l->list[mid] <= pid) |
cc31edce PM |
3575 | index = mid + 1; |
3576 | else | |
3577 | end = mid; | |
3578 | } | |
3579 | } | |
3580 | /* If we're off the end of the array, we're done */ | |
102a775e | 3581 | if (index >= l->length) |
cc31edce PM |
3582 | return NULL; |
3583 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 3584 | iter = l->list + index; |
cc31edce PM |
3585 | *pos = *iter; |
3586 | return iter; | |
3587 | } | |
3588 | ||
102a775e | 3589 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 3590 | { |
102a775e BB |
3591 | struct cgroup_pidlist *l = s->private; |
3592 | up_read(&l->mutex); | |
cc31edce PM |
3593 | } |
3594 | ||
102a775e | 3595 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 3596 | { |
102a775e BB |
3597 | struct cgroup_pidlist *l = s->private; |
3598 | pid_t *p = v; | |
3599 | pid_t *end = l->list + l->length; | |
cc31edce PM |
3600 | /* |
3601 | * Advance to the next pid in the array. If this goes off the | |
3602 | * end, we're done | |
3603 | */ | |
3604 | p++; | |
3605 | if (p >= end) { | |
3606 | return NULL; | |
3607 | } else { | |
3608 | *pos = *p; | |
3609 | return p; | |
3610 | } | |
3611 | } | |
3612 | ||
102a775e | 3613 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce PM |
3614 | { |
3615 | return seq_printf(s, "%d\n", *(int *)v); | |
3616 | } | |
bbcb81d0 | 3617 | |
102a775e BB |
3618 | /* |
3619 | * seq_operations functions for iterating on pidlists through seq_file - | |
3620 | * independent of whether it's tasks or procs | |
3621 | */ | |
3622 | static const struct seq_operations cgroup_pidlist_seq_operations = { | |
3623 | .start = cgroup_pidlist_start, | |
3624 | .stop = cgroup_pidlist_stop, | |
3625 | .next = cgroup_pidlist_next, | |
3626 | .show = cgroup_pidlist_show, | |
cc31edce PM |
3627 | }; |
3628 | ||
102a775e | 3629 | static void cgroup_release_pid_array(struct cgroup_pidlist *l) |
cc31edce | 3630 | { |
72a8cb30 BB |
3631 | /* |
3632 | * the case where we're the last user of this particular pidlist will | |
3633 | * have us remove it from the cgroup's list, which entails taking the | |
3634 | * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> | |
3635 | * pidlist_mutex, we have to take pidlist_mutex first. | |
3636 | */ | |
3637 | mutex_lock(&l->owner->pidlist_mutex); | |
102a775e BB |
3638 | down_write(&l->mutex); |
3639 | BUG_ON(!l->use_count); | |
3640 | if (!--l->use_count) { | |
72a8cb30 BB |
3641 | /* we're the last user if refcount is 0; remove and free */ |
3642 | list_del(&l->links); | |
3643 | mutex_unlock(&l->owner->pidlist_mutex); | |
d1d9fd33 | 3644 | pidlist_free(l->list); |
72a8cb30 BB |
3645 | put_pid_ns(l->key.ns); |
3646 | up_write(&l->mutex); | |
3647 | kfree(l); | |
3648 | return; | |
cc31edce | 3649 | } |
72a8cb30 | 3650 | mutex_unlock(&l->owner->pidlist_mutex); |
102a775e | 3651 | up_write(&l->mutex); |
bbcb81d0 PM |
3652 | } |
3653 | ||
102a775e | 3654 | static int cgroup_pidlist_release(struct inode *inode, struct file *file) |
cc31edce | 3655 | { |
102a775e | 3656 | struct cgroup_pidlist *l; |
cc31edce PM |
3657 | if (!(file->f_mode & FMODE_READ)) |
3658 | return 0; | |
102a775e BB |
3659 | /* |
3660 | * the seq_file will only be initialized if the file was opened for | |
3661 | * reading; hence we check if it's not null only in that case. | |
3662 | */ | |
3663 | l = ((struct seq_file *)file->private_data)->private; | |
3664 | cgroup_release_pid_array(l); | |
cc31edce PM |
3665 | return seq_release(inode, file); |
3666 | } | |
3667 | ||
102a775e | 3668 | static const struct file_operations cgroup_pidlist_operations = { |
cc31edce PM |
3669 | .read = seq_read, |
3670 | .llseek = seq_lseek, | |
3671 | .write = cgroup_file_write, | |
102a775e | 3672 | .release = cgroup_pidlist_release, |
cc31edce PM |
3673 | }; |
3674 | ||
bbcb81d0 | 3675 | /* |
102a775e BB |
3676 | * The following functions handle opens on a file that displays a pidlist |
3677 | * (tasks or procs). Prepare an array of the process/thread IDs of whoever's | |
3678 | * in the cgroup. | |
bbcb81d0 | 3679 | */ |
102a775e | 3680 | /* helper function for the two below it */ |
72a8cb30 | 3681 | static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) |
bbcb81d0 | 3682 | { |
bd89aabc | 3683 | struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); |
72a8cb30 | 3684 | struct cgroup_pidlist *l; |
cc31edce | 3685 | int retval; |
bbcb81d0 | 3686 | |
cc31edce | 3687 | /* Nothing to do for write-only files */ |
bbcb81d0 PM |
3688 | if (!(file->f_mode & FMODE_READ)) |
3689 | return 0; | |
3690 | ||
102a775e | 3691 | /* have the array populated */ |
72a8cb30 | 3692 | retval = pidlist_array_load(cgrp, type, &l); |
102a775e BB |
3693 | if (retval) |
3694 | return retval; | |
3695 | /* configure file information */ | |
3696 | file->f_op = &cgroup_pidlist_operations; | |
cc31edce | 3697 | |
102a775e | 3698 | retval = seq_open(file, &cgroup_pidlist_seq_operations); |
cc31edce | 3699 | if (retval) { |
102a775e | 3700 | cgroup_release_pid_array(l); |
cc31edce | 3701 | return retval; |
bbcb81d0 | 3702 | } |
102a775e | 3703 | ((struct seq_file *)file->private_data)->private = l; |
bbcb81d0 PM |
3704 | return 0; |
3705 | } | |
102a775e BB |
3706 | static int cgroup_tasks_open(struct inode *unused, struct file *file) |
3707 | { | |
72a8cb30 | 3708 | return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); |
102a775e BB |
3709 | } |
3710 | static int cgroup_procs_open(struct inode *unused, struct file *file) | |
3711 | { | |
72a8cb30 | 3712 | return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); |
102a775e | 3713 | } |
bbcb81d0 | 3714 | |
bd89aabc | 3715 | static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, |
81a6a5cd PM |
3716 | struct cftype *cft) |
3717 | { | |
bd89aabc | 3718 | return notify_on_release(cgrp); |
81a6a5cd PM |
3719 | } |
3720 | ||
6379c106 PM |
3721 | static int cgroup_write_notify_on_release(struct cgroup *cgrp, |
3722 | struct cftype *cft, | |
3723 | u64 val) | |
3724 | { | |
3725 | clear_bit(CGRP_RELEASABLE, &cgrp->flags); | |
3726 | if (val) | |
3727 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3728 | else | |
3729 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
3730 | return 0; | |
3731 | } | |
3732 | ||
0dea1168 KS |
3733 | /* |
3734 | * Unregister event and free resources. | |
3735 | * | |
3736 | * Gets called from workqueue. | |
3737 | */ | |
3738 | static void cgroup_event_remove(struct work_struct *work) | |
3739 | { | |
3740 | struct cgroup_event *event = container_of(work, struct cgroup_event, | |
3741 | remove); | |
3742 | struct cgroup *cgrp = event->cgrp; | |
3743 | ||
810cbee4 LZ |
3744 | remove_wait_queue(event->wqh, &event->wait); |
3745 | ||
0dea1168 KS |
3746 | event->cft->unregister_event(cgrp, event->cft, event->eventfd); |
3747 | ||
810cbee4 LZ |
3748 | /* Notify userspace the event is going away. */ |
3749 | eventfd_signal(event->eventfd, 1); | |
3750 | ||
0dea1168 | 3751 | eventfd_ctx_put(event->eventfd); |
0dea1168 | 3752 | kfree(event); |
a0a4db54 | 3753 | dput(cgrp->dentry); |
0dea1168 KS |
3754 | } |
3755 | ||
3756 | /* | |
3757 | * Gets called on POLLHUP on eventfd when user closes it. | |
3758 | * | |
3759 | * Called with wqh->lock held and interrupts disabled. | |
3760 | */ | |
3761 | static int cgroup_event_wake(wait_queue_t *wait, unsigned mode, | |
3762 | int sync, void *key) | |
3763 | { | |
3764 | struct cgroup_event *event = container_of(wait, | |
3765 | struct cgroup_event, wait); | |
3766 | struct cgroup *cgrp = event->cgrp; | |
3767 | unsigned long flags = (unsigned long)key; | |
3768 | ||
3769 | if (flags & POLLHUP) { | |
0dea1168 | 3770 | /* |
810cbee4 LZ |
3771 | * If the event has been detached at cgroup removal, we |
3772 | * can simply return knowing the other side will cleanup | |
3773 | * for us. | |
3774 | * | |
3775 | * We can't race against event freeing since the other | |
3776 | * side will require wqh->lock via remove_wait_queue(), | |
3777 | * which we hold. | |
0dea1168 | 3778 | */ |
810cbee4 LZ |
3779 | spin_lock(&cgrp->event_list_lock); |
3780 | if (!list_empty(&event->list)) { | |
3781 | list_del_init(&event->list); | |
3782 | /* | |
3783 | * We are in atomic context, but cgroup_event_remove() | |
3784 | * may sleep, so we have to call it in workqueue. | |
3785 | */ | |
3786 | schedule_work(&event->remove); | |
3787 | } | |
3788 | spin_unlock(&cgrp->event_list_lock); | |
0dea1168 KS |
3789 | } |
3790 | ||
3791 | return 0; | |
3792 | } | |
3793 | ||
3794 | static void cgroup_event_ptable_queue_proc(struct file *file, | |
3795 | wait_queue_head_t *wqh, poll_table *pt) | |
3796 | { | |
3797 | struct cgroup_event *event = container_of(pt, | |
3798 | struct cgroup_event, pt); | |
3799 | ||
3800 | event->wqh = wqh; | |
3801 | add_wait_queue(wqh, &event->wait); | |
3802 | } | |
3803 | ||
3804 | /* | |
3805 | * Parse input and register new cgroup event handler. | |
3806 | * | |
3807 | * Input must be in format '<event_fd> <control_fd> <args>'. | |
3808 | * Interpretation of args is defined by control file implementation. | |
3809 | */ | |
3810 | static int cgroup_write_event_control(struct cgroup *cgrp, struct cftype *cft, | |
3811 | const char *buffer) | |
3812 | { | |
3813 | struct cgroup_event *event = NULL; | |
f169007b | 3814 | struct cgroup *cgrp_cfile; |
0dea1168 KS |
3815 | unsigned int efd, cfd; |
3816 | struct file *efile = NULL; | |
3817 | struct file *cfile = NULL; | |
3818 | char *endp; | |
3819 | int ret; | |
3820 | ||
3821 | efd = simple_strtoul(buffer, &endp, 10); | |
3822 | if (*endp != ' ') | |
3823 | return -EINVAL; | |
3824 | buffer = endp + 1; | |
3825 | ||
3826 | cfd = simple_strtoul(buffer, &endp, 10); | |
3827 | if ((*endp != ' ') && (*endp != '\0')) | |
3828 | return -EINVAL; | |
3829 | buffer = endp + 1; | |
3830 | ||
3831 | event = kzalloc(sizeof(*event), GFP_KERNEL); | |
3832 | if (!event) | |
3833 | return -ENOMEM; | |
3834 | event->cgrp = cgrp; | |
3835 | INIT_LIST_HEAD(&event->list); | |
3836 | init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc); | |
3837 | init_waitqueue_func_entry(&event->wait, cgroup_event_wake); | |
3838 | INIT_WORK(&event->remove, cgroup_event_remove); | |
3839 | ||
3840 | efile = eventfd_fget(efd); | |
3841 | if (IS_ERR(efile)) { | |
3842 | ret = PTR_ERR(efile); | |
3843 | goto fail; | |
3844 | } | |
3845 | ||
3846 | event->eventfd = eventfd_ctx_fileget(efile); | |
3847 | if (IS_ERR(event->eventfd)) { | |
3848 | ret = PTR_ERR(event->eventfd); | |
3849 | goto fail; | |
3850 | } | |
3851 | ||
3852 | cfile = fget(cfd); | |
3853 | if (!cfile) { | |
3854 | ret = -EBADF; | |
3855 | goto fail; | |
3856 | } | |
3857 | ||
3858 | /* the process need read permission on control file */ | |
3bfa784a | 3859 | /* AV: shouldn't we check that it's been opened for read instead? */ |
496ad9aa | 3860 | ret = inode_permission(file_inode(cfile), MAY_READ); |
0dea1168 KS |
3861 | if (ret < 0) |
3862 | goto fail; | |
3863 | ||
3864 | event->cft = __file_cft(cfile); | |
3865 | if (IS_ERR(event->cft)) { | |
3866 | ret = PTR_ERR(event->cft); | |
3867 | goto fail; | |
3868 | } | |
3869 | ||
f169007b LZ |
3870 | /* |
3871 | * The file to be monitored must be in the same cgroup as | |
3872 | * cgroup.event_control is. | |
3873 | */ | |
3874 | cgrp_cfile = __d_cgrp(cfile->f_dentry->d_parent); | |
3875 | if (cgrp_cfile != cgrp) { | |
3876 | ret = -EINVAL; | |
3877 | goto fail; | |
3878 | } | |
3879 | ||
0dea1168 KS |
3880 | if (!event->cft->register_event || !event->cft->unregister_event) { |
3881 | ret = -EINVAL; | |
3882 | goto fail; | |
3883 | } | |
3884 | ||
3885 | ret = event->cft->register_event(cgrp, event->cft, | |
3886 | event->eventfd, buffer); | |
3887 | if (ret) | |
3888 | goto fail; | |
3889 | ||
7ef70e48 | 3890 | efile->f_op->poll(efile, &event->pt); |
0dea1168 | 3891 | |
a0a4db54 KS |
3892 | /* |
3893 | * Events should be removed after rmdir of cgroup directory, but before | |
3894 | * destroying subsystem state objects. Let's take reference to cgroup | |
3895 | * directory dentry to do that. | |
3896 | */ | |
3897 | dget(cgrp->dentry); | |
3898 | ||
0dea1168 KS |
3899 | spin_lock(&cgrp->event_list_lock); |
3900 | list_add(&event->list, &cgrp->event_list); | |
3901 | spin_unlock(&cgrp->event_list_lock); | |
3902 | ||
3903 | fput(cfile); | |
3904 | fput(efile); | |
3905 | ||
3906 | return 0; | |
3907 | ||
3908 | fail: | |
3909 | if (cfile) | |
3910 | fput(cfile); | |
3911 | ||
3912 | if (event && event->eventfd && !IS_ERR(event->eventfd)) | |
3913 | eventfd_ctx_put(event->eventfd); | |
3914 | ||
3915 | if (!IS_ERR_OR_NULL(efile)) | |
3916 | fput(efile); | |
3917 | ||
3918 | kfree(event); | |
3919 | ||
3920 | return ret; | |
3921 | } | |
3922 | ||
97978e6d DL |
3923 | static u64 cgroup_clone_children_read(struct cgroup *cgrp, |
3924 | struct cftype *cft) | |
3925 | { | |
2260e7fc | 3926 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
97978e6d DL |
3927 | } |
3928 | ||
3929 | static int cgroup_clone_children_write(struct cgroup *cgrp, | |
3930 | struct cftype *cft, | |
3931 | u64 val) | |
3932 | { | |
3933 | if (val) | |
2260e7fc | 3934 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
97978e6d | 3935 | else |
2260e7fc | 3936 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
97978e6d DL |
3937 | return 0; |
3938 | } | |
3939 | ||
bbcb81d0 PM |
3940 | /* |
3941 | * for the common functions, 'private' gives the type of file | |
3942 | */ | |
102a775e BB |
3943 | /* for hysterical raisins, we can't put this on the older files */ |
3944 | #define CGROUP_FILE_GENERIC_PREFIX "cgroup." | |
81a6a5cd PM |
3945 | static struct cftype files[] = { |
3946 | { | |
3947 | .name = "tasks", | |
3948 | .open = cgroup_tasks_open, | |
af351026 | 3949 | .write_u64 = cgroup_tasks_write, |
102a775e | 3950 | .release = cgroup_pidlist_release, |
099fca32 | 3951 | .mode = S_IRUGO | S_IWUSR, |
81a6a5cd | 3952 | }, |
102a775e BB |
3953 | { |
3954 | .name = CGROUP_FILE_GENERIC_PREFIX "procs", | |
3955 | .open = cgroup_procs_open, | |
74a1166d | 3956 | .write_u64 = cgroup_procs_write, |
102a775e | 3957 | .release = cgroup_pidlist_release, |
74a1166d | 3958 | .mode = S_IRUGO | S_IWUSR, |
102a775e | 3959 | }, |
81a6a5cd PM |
3960 | { |
3961 | .name = "notify_on_release", | |
f4c753b7 | 3962 | .read_u64 = cgroup_read_notify_on_release, |
6379c106 | 3963 | .write_u64 = cgroup_write_notify_on_release, |
81a6a5cd | 3964 | }, |
0dea1168 KS |
3965 | { |
3966 | .name = CGROUP_FILE_GENERIC_PREFIX "event_control", | |
3967 | .write_string = cgroup_write_event_control, | |
3968 | .mode = S_IWUGO, | |
3969 | }, | |
97978e6d DL |
3970 | { |
3971 | .name = "cgroup.clone_children", | |
873fe09e | 3972 | .flags = CFTYPE_INSANE, |
97978e6d DL |
3973 | .read_u64 = cgroup_clone_children_read, |
3974 | .write_u64 = cgroup_clone_children_write, | |
3975 | }, | |
873fe09e TH |
3976 | { |
3977 | .name = "cgroup.sane_behavior", | |
3978 | .flags = CFTYPE_ONLY_ON_ROOT, | |
3979 | .read_seq_string = cgroup_sane_behavior_show, | |
3980 | }, | |
6e6ff25b TH |
3981 | { |
3982 | .name = "release_agent", | |
3983 | .flags = CFTYPE_ONLY_ON_ROOT, | |
3984 | .read_seq_string = cgroup_release_agent_show, | |
3985 | .write_string = cgroup_release_agent_write, | |
3986 | .max_write_len = PATH_MAX, | |
3987 | }, | |
db0416b6 | 3988 | { } /* terminate */ |
bbcb81d0 PM |
3989 | }; |
3990 | ||
13af07df AR |
3991 | /** |
3992 | * cgroup_populate_dir - selectively creation of files in a directory | |
3993 | * @cgrp: target cgroup | |
3994 | * @base_files: true if the base files should be added | |
3995 | * @subsys_mask: mask of the subsystem ids whose files should be added | |
3996 | */ | |
3997 | static int cgroup_populate_dir(struct cgroup *cgrp, bool base_files, | |
3998 | unsigned long subsys_mask) | |
ddbcc7e8 PM |
3999 | { |
4000 | int err; | |
4001 | struct cgroup_subsys *ss; | |
4002 | ||
13af07df AR |
4003 | if (base_files) { |
4004 | err = cgroup_addrm_files(cgrp, NULL, files, true); | |
4005 | if (err < 0) | |
4006 | return err; | |
4007 | } | |
bbcb81d0 | 4008 | |
8e3f6541 | 4009 | /* process cftsets of each subsystem */ |
bd89aabc | 4010 | for_each_subsys(cgrp->root, ss) { |
8e3f6541 | 4011 | struct cftype_set *set; |
13af07df AR |
4012 | if (!test_bit(ss->subsys_id, &subsys_mask)) |
4013 | continue; | |
8e3f6541 | 4014 | |
db0416b6 | 4015 | list_for_each_entry(set, &ss->cftsets, node) |
79578621 | 4016 | cgroup_addrm_files(cgrp, ss, set->cfts, true); |
ddbcc7e8 | 4017 | } |
8e3f6541 | 4018 | |
38460b48 KH |
4019 | /* This cgroup is ready now */ |
4020 | for_each_subsys(cgrp->root, ss) { | |
4021 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
4022 | /* | |
4023 | * Update id->css pointer and make this css visible from | |
4024 | * CSS ID functions. This pointer will be dereferened | |
4025 | * from RCU-read-side without locks. | |
4026 | */ | |
4027 | if (css->id) | |
4028 | rcu_assign_pointer(css->id->css, css); | |
4029 | } | |
ddbcc7e8 PM |
4030 | |
4031 | return 0; | |
4032 | } | |
4033 | ||
48ddbe19 TH |
4034 | static void css_dput_fn(struct work_struct *work) |
4035 | { | |
4036 | struct cgroup_subsys_state *css = | |
4037 | container_of(work, struct cgroup_subsys_state, dput_work); | |
5db9a4d9 TH |
4038 | struct dentry *dentry = css->cgroup->dentry; |
4039 | struct super_block *sb = dentry->d_sb; | |
48ddbe19 | 4040 | |
5db9a4d9 TH |
4041 | atomic_inc(&sb->s_active); |
4042 | dput(dentry); | |
4043 | deactivate_super(sb); | |
48ddbe19 TH |
4044 | } |
4045 | ||
ddbcc7e8 PM |
4046 | static void init_cgroup_css(struct cgroup_subsys_state *css, |
4047 | struct cgroup_subsys *ss, | |
bd89aabc | 4048 | struct cgroup *cgrp) |
ddbcc7e8 | 4049 | { |
bd89aabc | 4050 | css->cgroup = cgrp; |
e7c5ec91 | 4051 | atomic_set(&css->refcnt, 1); |
ddbcc7e8 | 4052 | css->flags = 0; |
38460b48 | 4053 | css->id = NULL; |
bd89aabc | 4054 | if (cgrp == dummytop) |
38b53aba | 4055 | css->flags |= CSS_ROOT; |
bd89aabc PM |
4056 | BUG_ON(cgrp->subsys[ss->subsys_id]); |
4057 | cgrp->subsys[ss->subsys_id] = css; | |
48ddbe19 TH |
4058 | |
4059 | /* | |
ed957793 TH |
4060 | * css holds an extra ref to @cgrp->dentry which is put on the last |
4061 | * css_put(). dput() requires process context, which css_put() may | |
4062 | * be called without. @css->dput_work will be used to invoke | |
4063 | * dput() asynchronously from css_put(). | |
48ddbe19 TH |
4064 | */ |
4065 | INIT_WORK(&css->dput_work, css_dput_fn); | |
ddbcc7e8 PM |
4066 | } |
4067 | ||
b1929db4 TH |
4068 | /* invoke ->post_create() on a new CSS and mark it online if successful */ |
4069 | static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) | |
a31f2d3f | 4070 | { |
b1929db4 TH |
4071 | int ret = 0; |
4072 | ||
a31f2d3f TH |
4073 | lockdep_assert_held(&cgroup_mutex); |
4074 | ||
92fb9748 TH |
4075 | if (ss->css_online) |
4076 | ret = ss->css_online(cgrp); | |
b1929db4 TH |
4077 | if (!ret) |
4078 | cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE; | |
4079 | return ret; | |
a31f2d3f TH |
4080 | } |
4081 | ||
4082 | /* if the CSS is online, invoke ->pre_destory() on it and mark it offline */ | |
4083 | static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp) | |
4084 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
4085 | { | |
4086 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
4087 | ||
4088 | lockdep_assert_held(&cgroup_mutex); | |
4089 | ||
4090 | if (!(css->flags & CSS_ONLINE)) | |
4091 | return; | |
4092 | ||
d7eeac19 | 4093 | if (ss->css_offline) |
92fb9748 | 4094 | ss->css_offline(cgrp); |
a31f2d3f TH |
4095 | |
4096 | cgrp->subsys[ss->subsys_id]->flags &= ~CSS_ONLINE; | |
4097 | } | |
4098 | ||
ddbcc7e8 | 4099 | /* |
a043e3b2 LZ |
4100 | * cgroup_create - create a cgroup |
4101 | * @parent: cgroup that will be parent of the new cgroup | |
4102 | * @dentry: dentry of the new cgroup | |
4103 | * @mode: mode to set on new inode | |
ddbcc7e8 | 4104 | * |
a043e3b2 | 4105 | * Must be called with the mutex on the parent inode held |
ddbcc7e8 | 4106 | */ |
ddbcc7e8 | 4107 | static long cgroup_create(struct cgroup *parent, struct dentry *dentry, |
a5e7ed32 | 4108 | umode_t mode) |
ddbcc7e8 | 4109 | { |
bd89aabc | 4110 | struct cgroup *cgrp; |
65dff759 | 4111 | struct cgroup_name *name; |
ddbcc7e8 PM |
4112 | struct cgroupfs_root *root = parent->root; |
4113 | int err = 0; | |
4114 | struct cgroup_subsys *ss; | |
4115 | struct super_block *sb = root->sb; | |
4116 | ||
0a950f65 | 4117 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc PM |
4118 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
4119 | if (!cgrp) | |
ddbcc7e8 PM |
4120 | return -ENOMEM; |
4121 | ||
65dff759 LZ |
4122 | name = cgroup_alloc_name(dentry); |
4123 | if (!name) | |
4124 | goto err_free_cgrp; | |
4125 | rcu_assign_pointer(cgrp->name, name); | |
4126 | ||
0a950f65 TH |
4127 | cgrp->id = ida_simple_get(&root->cgroup_ida, 1, 0, GFP_KERNEL); |
4128 | if (cgrp->id < 0) | |
65dff759 | 4129 | goto err_free_name; |
0a950f65 | 4130 | |
976c06bc TH |
4131 | /* |
4132 | * Only live parents can have children. Note that the liveliness | |
4133 | * check isn't strictly necessary because cgroup_mkdir() and | |
4134 | * cgroup_rmdir() are fully synchronized by i_mutex; however, do it | |
4135 | * anyway so that locking is contained inside cgroup proper and we | |
4136 | * don't get nasty surprises if we ever grow another caller. | |
4137 | */ | |
4138 | if (!cgroup_lock_live_group(parent)) { | |
4139 | err = -ENODEV; | |
0a950f65 | 4140 | goto err_free_id; |
976c06bc TH |
4141 | } |
4142 | ||
ddbcc7e8 PM |
4143 | /* Grab a reference on the superblock so the hierarchy doesn't |
4144 | * get deleted on unmount if there are child cgroups. This | |
4145 | * can be done outside cgroup_mutex, since the sb can't | |
4146 | * disappear while someone has an open control file on the | |
4147 | * fs */ | |
4148 | atomic_inc(&sb->s_active); | |
4149 | ||
cc31edce | 4150 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4151 | |
fe1c06ca LZ |
4152 | dentry->d_fsdata = cgrp; |
4153 | cgrp->dentry = dentry; | |
4154 | ||
bd89aabc PM |
4155 | cgrp->parent = parent; |
4156 | cgrp->root = parent->root; | |
ddbcc7e8 | 4157 | |
b6abdb0e LZ |
4158 | if (notify_on_release(parent)) |
4159 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4160 | ||
2260e7fc TH |
4161 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4162 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4163 | |
ddbcc7e8 | 4164 | for_each_subsys(root, ss) { |
8c7f6edb | 4165 | struct cgroup_subsys_state *css; |
4528fd05 | 4166 | |
92fb9748 | 4167 | css = ss->css_alloc(cgrp); |
ddbcc7e8 PM |
4168 | if (IS_ERR(css)) { |
4169 | err = PTR_ERR(css); | |
4b8b47eb | 4170 | goto err_free_all; |
ddbcc7e8 | 4171 | } |
bd89aabc | 4172 | init_cgroup_css(css, ss, cgrp); |
4528fd05 LZ |
4173 | if (ss->use_id) { |
4174 | err = alloc_css_id(ss, parent, cgrp); | |
4175 | if (err) | |
4b8b47eb | 4176 | goto err_free_all; |
4528fd05 | 4177 | } |
ddbcc7e8 PM |
4178 | } |
4179 | ||
4e139afc TH |
4180 | /* |
4181 | * Create directory. cgroup_create_file() returns with the new | |
4182 | * directory locked on success so that it can be populated without | |
4183 | * dropping cgroup_mutex. | |
4184 | */ | |
28fd6f30 | 4185 | err = cgroup_create_file(dentry, S_IFDIR | mode, sb); |
ddbcc7e8 | 4186 | if (err < 0) |
4b8b47eb | 4187 | goto err_free_all; |
4e139afc | 4188 | lockdep_assert_held(&dentry->d_inode->i_mutex); |
ddbcc7e8 | 4189 | |
4e139afc | 4190 | /* allocation complete, commit to creation */ |
4e139afc TH |
4191 | list_add_tail(&cgrp->allcg_node, &root->allcg_list); |
4192 | list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); | |
4193 | root->number_of_cgroups++; | |
28fd6f30 | 4194 | |
b1929db4 TH |
4195 | /* each css holds a ref to the cgroup's dentry */ |
4196 | for_each_subsys(root, ss) | |
ed957793 | 4197 | dget(dentry); |
48ddbe19 | 4198 | |
415cf07a LZ |
4199 | /* hold a ref to the parent's dentry */ |
4200 | dget(parent->dentry); | |
4201 | ||
b1929db4 TH |
4202 | /* creation succeeded, notify subsystems */ |
4203 | for_each_subsys(root, ss) { | |
4204 | err = online_css(ss, cgrp); | |
4205 | if (err) | |
4206 | goto err_destroy; | |
1f869e87 GC |
4207 | |
4208 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && | |
4209 | parent->parent) { | |
4210 | 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", | |
4211 | current->comm, current->pid, ss->name); | |
4212 | if (!strcmp(ss->name, "memory")) | |
4213 | pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n"); | |
4214 | ss->warned_broken_hierarchy = true; | |
4215 | } | |
a8638030 TH |
4216 | } |
4217 | ||
a1a71b45 | 4218 | err = cgroup_populate_dir(cgrp, true, root->subsys_mask); |
4b8b47eb TH |
4219 | if (err) |
4220 | goto err_destroy; | |
ddbcc7e8 PM |
4221 | |
4222 | mutex_unlock(&cgroup_mutex); | |
bd89aabc | 4223 | mutex_unlock(&cgrp->dentry->d_inode->i_mutex); |
ddbcc7e8 PM |
4224 | |
4225 | return 0; | |
4226 | ||
4b8b47eb | 4227 | err_free_all: |
ddbcc7e8 | 4228 | for_each_subsys(root, ss) { |
bd89aabc | 4229 | if (cgrp->subsys[ss->subsys_id]) |
92fb9748 | 4230 | ss->css_free(cgrp); |
ddbcc7e8 | 4231 | } |
ddbcc7e8 | 4232 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
4233 | /* Release the reference count that we took on the superblock */ |
4234 | deactivate_super(sb); | |
0a950f65 TH |
4235 | err_free_id: |
4236 | ida_simple_remove(&root->cgroup_ida, cgrp->id); | |
65dff759 LZ |
4237 | err_free_name: |
4238 | kfree(rcu_dereference_raw(cgrp->name)); | |
4b8b47eb | 4239 | err_free_cgrp: |
bd89aabc | 4240 | kfree(cgrp); |
ddbcc7e8 | 4241 | return err; |
4b8b47eb TH |
4242 | |
4243 | err_destroy: | |
4244 | cgroup_destroy_locked(cgrp); | |
4245 | mutex_unlock(&cgroup_mutex); | |
4246 | mutex_unlock(&dentry->d_inode->i_mutex); | |
4247 | return err; | |
ddbcc7e8 PM |
4248 | } |
4249 | ||
18bb1db3 | 4250 | static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
ddbcc7e8 PM |
4251 | { |
4252 | struct cgroup *c_parent = dentry->d_parent->d_fsdata; | |
4253 | ||
4254 | /* the vfs holds inode->i_mutex already */ | |
4255 | return cgroup_create(c_parent, dentry, mode | S_IFDIR); | |
4256 | } | |
4257 | ||
42809dd4 TH |
4258 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4259 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4260 | { |
42809dd4 TH |
4261 | struct dentry *d = cgrp->dentry; |
4262 | struct cgroup *parent = cgrp->parent; | |
4ab78683 | 4263 | struct cgroup_event *event, *tmp; |
ed957793 | 4264 | struct cgroup_subsys *ss; |
ddbcc7e8 | 4265 | |
42809dd4 TH |
4266 | lockdep_assert_held(&d->d_inode->i_mutex); |
4267 | lockdep_assert_held(&cgroup_mutex); | |
4268 | ||
4269 | if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) | |
ddbcc7e8 | 4270 | return -EBUSY; |
a043e3b2 | 4271 | |
88703267 | 4272 | /* |
1a90dd50 TH |
4273 | * Block new css_tryget() by deactivating refcnt and mark @cgrp |
4274 | * removed. This makes future css_tryget() and child creation | |
4275 | * attempts fail thus maintaining the removal conditions verified | |
4276 | * above. | |
88703267 | 4277 | */ |
ed957793 TH |
4278 | for_each_subsys(cgrp->root, ss) { |
4279 | struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; | |
88703267 | 4280 | |
ed957793 TH |
4281 | WARN_ON(atomic_read(&css->refcnt) < 0); |
4282 | atomic_add(CSS_DEACT_BIAS, &css->refcnt); | |
88703267 | 4283 | } |
1a90dd50 | 4284 | set_bit(CGRP_REMOVED, &cgrp->flags); |
ddbcc7e8 | 4285 | |
a31f2d3f | 4286 | /* tell subsystems to initate destruction */ |
1a90dd50 | 4287 | for_each_subsys(cgrp->root, ss) |
a31f2d3f | 4288 | offline_css(ss, cgrp); |
ed957793 TH |
4289 | |
4290 | /* | |
ed957793 TH |
4291 | * Put all the base refs. Each css holds an extra reference to the |
4292 | * cgroup's dentry and cgroup removal proceeds regardless of css | |
4293 | * refs. On the last put of each css, whenever that may be, the | |
4294 | * extra dentry ref is put so that dentry destruction happens only | |
4295 | * after all css's are released. | |
4296 | */ | |
e9316080 TH |
4297 | for_each_subsys(cgrp->root, ss) |
4298 | css_put(cgrp->subsys[ss->subsys_id]); | |
ddbcc7e8 | 4299 | |
cdcc136f | 4300 | raw_spin_lock(&release_list_lock); |
bd89aabc | 4301 | if (!list_empty(&cgrp->release_list)) |
8d258797 | 4302 | list_del_init(&cgrp->release_list); |
cdcc136f | 4303 | raw_spin_unlock(&release_list_lock); |
999cd8a4 | 4304 | |
999cd8a4 | 4305 | /* delete this cgroup from parent->children */ |
eb6fd504 | 4306 | list_del_rcu(&cgrp->sibling); |
b0ca5a84 TH |
4307 | list_del_init(&cgrp->allcg_node); |
4308 | ||
42809dd4 | 4309 | dget(d); |
ddbcc7e8 PM |
4310 | cgroup_d_remove_dir(d); |
4311 | dput(d); | |
ddbcc7e8 | 4312 | |
bd89aabc | 4313 | set_bit(CGRP_RELEASABLE, &parent->flags); |
81a6a5cd PM |
4314 | check_for_release(parent); |
4315 | ||
4ab78683 KS |
4316 | /* |
4317 | * Unregister events and notify userspace. | |
4318 | * Notify userspace about cgroup removing only after rmdir of cgroup | |
810cbee4 | 4319 | * directory to avoid race between userspace and kernelspace. |
4ab78683 KS |
4320 | */ |
4321 | spin_lock(&cgrp->event_list_lock); | |
810cbee4 | 4322 | list_for_each_entry_safe(event, tmp, &cgrp->event_list, list) { |
9718ceb3 | 4323 | list_del_init(&event->list); |
4ab78683 KS |
4324 | schedule_work(&event->remove); |
4325 | } | |
810cbee4 | 4326 | spin_unlock(&cgrp->event_list_lock); |
4ab78683 | 4327 | |
ddbcc7e8 PM |
4328 | return 0; |
4329 | } | |
4330 | ||
42809dd4 TH |
4331 | static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) |
4332 | { | |
4333 | int ret; | |
4334 | ||
4335 | mutex_lock(&cgroup_mutex); | |
4336 | ret = cgroup_destroy_locked(dentry->d_fsdata); | |
4337 | mutex_unlock(&cgroup_mutex); | |
4338 | ||
4339 | return ret; | |
4340 | } | |
4341 | ||
8e3f6541 TH |
4342 | static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) |
4343 | { | |
4344 | INIT_LIST_HEAD(&ss->cftsets); | |
4345 | ||
4346 | /* | |
4347 | * base_cftset is embedded in subsys itself, no need to worry about | |
4348 | * deregistration. | |
4349 | */ | |
4350 | if (ss->base_cftypes) { | |
4351 | ss->base_cftset.cfts = ss->base_cftypes; | |
4352 | list_add_tail(&ss->base_cftset.node, &ss->cftsets); | |
4353 | } | |
4354 | } | |
4355 | ||
06a11920 | 4356 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss) |
ddbcc7e8 | 4357 | { |
ddbcc7e8 | 4358 | struct cgroup_subsys_state *css; |
cfe36bde DC |
4359 | |
4360 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 4361 | |
648bb56d TH |
4362 | mutex_lock(&cgroup_mutex); |
4363 | ||
8e3f6541 TH |
4364 | /* init base cftset */ |
4365 | cgroup_init_cftsets(ss); | |
4366 | ||
ddbcc7e8 | 4367 | /* Create the top cgroup state for this subsystem */ |
33a68ac1 | 4368 | list_add(&ss->sibling, &rootnode.subsys_list); |
ddbcc7e8 | 4369 | ss->root = &rootnode; |
92fb9748 | 4370 | css = ss->css_alloc(dummytop); |
ddbcc7e8 PM |
4371 | /* We don't handle early failures gracefully */ |
4372 | BUG_ON(IS_ERR(css)); | |
4373 | init_cgroup_css(css, ss, dummytop); | |
4374 | ||
e8d55fde | 4375 | /* Update the init_css_set to contain a subsys |
817929ec | 4376 | * pointer to this state - since the subsystem is |
e8d55fde LZ |
4377 | * newly registered, all tasks and hence the |
4378 | * init_css_set is in the subsystem's top cgroup. */ | |
b48c6a80 | 4379 | init_css_set.subsys[ss->subsys_id] = css; |
ddbcc7e8 PM |
4380 | |
4381 | need_forkexit_callback |= ss->fork || ss->exit; | |
4382 | ||
e8d55fde LZ |
4383 | /* At system boot, before all subsystems have been |
4384 | * registered, no tasks have been forked, so we don't | |
4385 | * need to invoke fork callbacks here. */ | |
4386 | BUG_ON(!list_empty(&init_task.tasks)); | |
4387 | ||
b1929db4 | 4388 | BUG_ON(online_css(ss, dummytop)); |
a8638030 | 4389 | |
648bb56d TH |
4390 | mutex_unlock(&cgroup_mutex); |
4391 | ||
e6a1105b BB |
4392 | /* this function shouldn't be used with modular subsystems, since they |
4393 | * need to register a subsys_id, among other things */ | |
4394 | BUG_ON(ss->module); | |
4395 | } | |
4396 | ||
4397 | /** | |
4398 | * cgroup_load_subsys: load and register a modular subsystem at runtime | |
4399 | * @ss: the subsystem to load | |
4400 | * | |
4401 | * This function should be called in a modular subsystem's initcall. If the | |
88393161 | 4402 | * subsystem is built as a module, it will be assigned a new subsys_id and set |
e6a1105b BB |
4403 | * up for use. If the subsystem is built-in anyway, work is delegated to the |
4404 | * simpler cgroup_init_subsys. | |
4405 | */ | |
4406 | int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) | |
4407 | { | |
e6a1105b | 4408 | struct cgroup_subsys_state *css; |
d19e19de | 4409 | int i, ret; |
b67bfe0d | 4410 | struct hlist_node *tmp; |
0ac801fe LZ |
4411 | struct css_set *cg; |
4412 | unsigned long key; | |
e6a1105b BB |
4413 | |
4414 | /* check name and function validity */ | |
4415 | if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || | |
92fb9748 | 4416 | ss->css_alloc == NULL || ss->css_free == NULL) |
e6a1105b BB |
4417 | return -EINVAL; |
4418 | ||
4419 | /* | |
4420 | * we don't support callbacks in modular subsystems. this check is | |
4421 | * before the ss->module check for consistency; a subsystem that could | |
4422 | * be a module should still have no callbacks even if the user isn't | |
4423 | * compiling it as one. | |
4424 | */ | |
4425 | if (ss->fork || ss->exit) | |
4426 | return -EINVAL; | |
4427 | ||
4428 | /* | |
4429 | * an optionally modular subsystem is built-in: we want to do nothing, | |
4430 | * since cgroup_init_subsys will have already taken care of it. | |
4431 | */ | |
4432 | if (ss->module == NULL) { | |
be45c900 | 4433 | /* a sanity check */ |
e6a1105b BB |
4434 | BUG_ON(subsys[ss->subsys_id] != ss); |
4435 | return 0; | |
4436 | } | |
4437 | ||
8e3f6541 TH |
4438 | /* init base cftset */ |
4439 | cgroup_init_cftsets(ss); | |
4440 | ||
e6a1105b | 4441 | mutex_lock(&cgroup_mutex); |
8a8e04df | 4442 | subsys[ss->subsys_id] = ss; |
e6a1105b BB |
4443 | |
4444 | /* | |
92fb9748 TH |
4445 | * no ss->css_alloc seems to need anything important in the ss |
4446 | * struct, so this can happen first (i.e. before the rootnode | |
4447 | * attachment). | |
e6a1105b | 4448 | */ |
92fb9748 | 4449 | css = ss->css_alloc(dummytop); |
e6a1105b BB |
4450 | if (IS_ERR(css)) { |
4451 | /* failure case - need to deassign the subsys[] slot. */ | |
8a8e04df | 4452 | subsys[ss->subsys_id] = NULL; |
e6a1105b BB |
4453 | mutex_unlock(&cgroup_mutex); |
4454 | return PTR_ERR(css); | |
4455 | } | |
4456 | ||
4457 | list_add(&ss->sibling, &rootnode.subsys_list); | |
4458 | ss->root = &rootnode; | |
4459 | ||
4460 | /* our new subsystem will be attached to the dummy hierarchy. */ | |
4461 | init_cgroup_css(css, ss, dummytop); | |
4462 | /* init_idr must be after init_cgroup_css because it sets css->id. */ | |
4463 | if (ss->use_id) { | |
d19e19de TH |
4464 | ret = cgroup_init_idr(ss, css); |
4465 | if (ret) | |
4466 | goto err_unload; | |
e6a1105b BB |
4467 | } |
4468 | ||
4469 | /* | |
4470 | * Now we need to entangle the css into the existing css_sets. unlike | |
4471 | * in cgroup_init_subsys, there are now multiple css_sets, so each one | |
4472 | * will need a new pointer to it; done by iterating the css_set_table. | |
4473 | * furthermore, modifying the existing css_sets will corrupt the hash | |
4474 | * table state, so each changed css_set will need its hash recomputed. | |
4475 | * this is all done under the css_set_lock. | |
4476 | */ | |
4477 | write_lock(&css_set_lock); | |
b67bfe0d | 4478 | hash_for_each_safe(css_set_table, i, tmp, cg, hlist) { |
0ac801fe LZ |
4479 | /* skip entries that we already rehashed */ |
4480 | if (cg->subsys[ss->subsys_id]) | |
4481 | continue; | |
4482 | /* remove existing entry */ | |
4483 | hash_del(&cg->hlist); | |
4484 | /* set new value */ | |
4485 | cg->subsys[ss->subsys_id] = css; | |
4486 | /* recompute hash and restore entry */ | |
4487 | key = css_set_hash(cg->subsys); | |
b67bfe0d | 4488 | hash_add(css_set_table, &cg->hlist, key); |
e6a1105b BB |
4489 | } |
4490 | write_unlock(&css_set_lock); | |
4491 | ||
b1929db4 TH |
4492 | ret = online_css(ss, dummytop); |
4493 | if (ret) | |
4494 | goto err_unload; | |
a8638030 | 4495 | |
e6a1105b BB |
4496 | /* success! */ |
4497 | mutex_unlock(&cgroup_mutex); | |
4498 | return 0; | |
d19e19de TH |
4499 | |
4500 | err_unload: | |
4501 | mutex_unlock(&cgroup_mutex); | |
4502 | /* @ss can't be mounted here as try_module_get() would fail */ | |
4503 | cgroup_unload_subsys(ss); | |
4504 | return ret; | |
ddbcc7e8 | 4505 | } |
e6a1105b | 4506 | EXPORT_SYMBOL_GPL(cgroup_load_subsys); |
ddbcc7e8 | 4507 | |
cf5d5941 BB |
4508 | /** |
4509 | * cgroup_unload_subsys: unload a modular subsystem | |
4510 | * @ss: the subsystem to unload | |
4511 | * | |
4512 | * This function should be called in a modular subsystem's exitcall. When this | |
4513 | * function is invoked, the refcount on the subsystem's module will be 0, so | |
4514 | * the subsystem will not be attached to any hierarchy. | |
4515 | */ | |
4516 | void cgroup_unload_subsys(struct cgroup_subsys *ss) | |
4517 | { | |
4518 | struct cg_cgroup_link *link; | |
cf5d5941 BB |
4519 | |
4520 | BUG_ON(ss->module == NULL); | |
4521 | ||
4522 | /* | |
4523 | * we shouldn't be called if the subsystem is in use, and the use of | |
4524 | * try_module_get in parse_cgroupfs_options should ensure that it | |
4525 | * doesn't start being used while we're killing it off. | |
4526 | */ | |
4527 | BUG_ON(ss->root != &rootnode); | |
4528 | ||
4529 | mutex_lock(&cgroup_mutex); | |
02ae7486 | 4530 | |
a31f2d3f | 4531 | offline_css(ss, dummytop); |
02ae7486 | 4532 | |
c897ff68 | 4533 | if (ss->use_id) |
02ae7486 | 4534 | idr_destroy(&ss->idr); |
02ae7486 | 4535 | |
cf5d5941 | 4536 | /* deassign the subsys_id */ |
cf5d5941 BB |
4537 | subsys[ss->subsys_id] = NULL; |
4538 | ||
4539 | /* remove subsystem from rootnode's list of subsystems */ | |
8d258797 | 4540 | list_del_init(&ss->sibling); |
cf5d5941 BB |
4541 | |
4542 | /* | |
4543 | * disentangle the css from all css_sets attached to the dummytop. as | |
4544 | * in loading, we need to pay our respects to the hashtable gods. | |
4545 | */ | |
4546 | write_lock(&css_set_lock); | |
4547 | list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) { | |
4548 | struct css_set *cg = link->cg; | |
0ac801fe | 4549 | unsigned long key; |
cf5d5941 | 4550 | |
0ac801fe | 4551 | hash_del(&cg->hlist); |
cf5d5941 | 4552 | cg->subsys[ss->subsys_id] = NULL; |
0ac801fe LZ |
4553 | key = css_set_hash(cg->subsys); |
4554 | hash_add(css_set_table, &cg->hlist, key); | |
cf5d5941 BB |
4555 | } |
4556 | write_unlock(&css_set_lock); | |
4557 | ||
4558 | /* | |
92fb9748 TH |
4559 | * remove subsystem's css from the dummytop and free it - need to |
4560 | * free before marking as null because ss->css_free needs the | |
4561 | * cgrp->subsys pointer to find their state. note that this also | |
4562 | * takes care of freeing the css_id. | |
cf5d5941 | 4563 | */ |
92fb9748 | 4564 | ss->css_free(dummytop); |
cf5d5941 BB |
4565 | dummytop->subsys[ss->subsys_id] = NULL; |
4566 | ||
4567 | mutex_unlock(&cgroup_mutex); | |
4568 | } | |
4569 | EXPORT_SYMBOL_GPL(cgroup_unload_subsys); | |
4570 | ||
ddbcc7e8 | 4571 | /** |
a043e3b2 LZ |
4572 | * cgroup_init_early - cgroup initialization at system boot |
4573 | * | |
4574 | * Initialize cgroups at system boot, and initialize any | |
4575 | * subsystems that request early init. | |
ddbcc7e8 PM |
4576 | */ |
4577 | int __init cgroup_init_early(void) | |
4578 | { | |
4579 | int i; | |
146aa1bd | 4580 | atomic_set(&init_css_set.refcount, 1); |
817929ec PM |
4581 | INIT_LIST_HEAD(&init_css_set.cg_links); |
4582 | INIT_LIST_HEAD(&init_css_set.tasks); | |
472b1053 | 4583 | INIT_HLIST_NODE(&init_css_set.hlist); |
817929ec | 4584 | css_set_count = 1; |
ddbcc7e8 | 4585 | init_cgroup_root(&rootnode); |
817929ec PM |
4586 | root_count = 1; |
4587 | init_task.cgroups = &init_css_set; | |
4588 | ||
4589 | init_css_set_link.cg = &init_css_set; | |
7717f7ba | 4590 | init_css_set_link.cgrp = dummytop; |
bd89aabc | 4591 | list_add(&init_css_set_link.cgrp_link_list, |
817929ec PM |
4592 | &rootnode.top_cgroup.css_sets); |
4593 | list_add(&init_css_set_link.cg_link_list, | |
4594 | &init_css_set.cg_links); | |
ddbcc7e8 | 4595 | |
be45c900 | 4596 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
ddbcc7e8 PM |
4597 | struct cgroup_subsys *ss = subsys[i]; |
4598 | ||
be45c900 DW |
4599 | /* at bootup time, we don't worry about modular subsystems */ |
4600 | if (!ss || ss->module) | |
4601 | continue; | |
4602 | ||
ddbcc7e8 PM |
4603 | BUG_ON(!ss->name); |
4604 | BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); | |
92fb9748 TH |
4605 | BUG_ON(!ss->css_alloc); |
4606 | BUG_ON(!ss->css_free); | |
ddbcc7e8 | 4607 | if (ss->subsys_id != i) { |
cfe36bde | 4608 | printk(KERN_ERR "cgroup: Subsys %s id == %d\n", |
ddbcc7e8 PM |
4609 | ss->name, ss->subsys_id); |
4610 | BUG(); | |
4611 | } | |
4612 | ||
4613 | if (ss->early_init) | |
4614 | cgroup_init_subsys(ss); | |
4615 | } | |
4616 | return 0; | |
4617 | } | |
4618 | ||
4619 | /** | |
a043e3b2 LZ |
4620 | * cgroup_init - cgroup initialization |
4621 | * | |
4622 | * Register cgroup filesystem and /proc file, and initialize | |
4623 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
4624 | */ |
4625 | int __init cgroup_init(void) | |
4626 | { | |
4627 | int err; | |
4628 | int i; | |
0ac801fe | 4629 | unsigned long key; |
a424316c PM |
4630 | |
4631 | err = bdi_init(&cgroup_backing_dev_info); | |
4632 | if (err) | |
4633 | return err; | |
ddbcc7e8 | 4634 | |
be45c900 | 4635 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
ddbcc7e8 | 4636 | struct cgroup_subsys *ss = subsys[i]; |
be45c900 DW |
4637 | |
4638 | /* at bootup time, we don't worry about modular subsystems */ | |
4639 | if (!ss || ss->module) | |
4640 | continue; | |
ddbcc7e8 PM |
4641 | if (!ss->early_init) |
4642 | cgroup_init_subsys(ss); | |
38460b48 | 4643 | if (ss->use_id) |
e6a1105b | 4644 | cgroup_init_idr(ss, init_css_set.subsys[ss->subsys_id]); |
ddbcc7e8 PM |
4645 | } |
4646 | ||
472b1053 | 4647 | /* Add init_css_set to the hash table */ |
0ac801fe LZ |
4648 | key = css_set_hash(init_css_set.subsys); |
4649 | hash_add(css_set_table, &init_css_set.hlist, key); | |
fa3ca07e TH |
4650 | |
4651 | /* allocate id for the dummy hierarchy */ | |
54e7b4eb TH |
4652 | mutex_lock(&cgroup_mutex); |
4653 | mutex_lock(&cgroup_root_mutex); | |
4654 | ||
fa3ca07e | 4655 | BUG_ON(cgroup_init_root_id(&rootnode)); |
676db4af | 4656 | |
54e7b4eb TH |
4657 | mutex_unlock(&cgroup_root_mutex); |
4658 | mutex_unlock(&cgroup_mutex); | |
4659 | ||
676db4af GKH |
4660 | cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); |
4661 | if (!cgroup_kobj) { | |
4662 | err = -ENOMEM; | |
4663 | goto out; | |
4664 | } | |
4665 | ||
ddbcc7e8 | 4666 | err = register_filesystem(&cgroup_fs_type); |
676db4af GKH |
4667 | if (err < 0) { |
4668 | kobject_put(cgroup_kobj); | |
ddbcc7e8 | 4669 | goto out; |
676db4af | 4670 | } |
ddbcc7e8 | 4671 | |
46ae220b | 4672 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
a424316c | 4673 | |
ddbcc7e8 | 4674 | out: |
a424316c PM |
4675 | if (err) |
4676 | bdi_destroy(&cgroup_backing_dev_info); | |
4677 | ||
ddbcc7e8 PM |
4678 | return err; |
4679 | } | |
b4f48b63 | 4680 | |
a424316c PM |
4681 | /* |
4682 | * proc_cgroup_show() | |
4683 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
4684 | * - Used for /proc/<pid>/cgroup. | |
4685 | * - No need to task_lock(tsk) on this tsk->cgroup reference, as it | |
4686 | * doesn't really matter if tsk->cgroup changes after we read it, | |
956db3ca | 4687 | * and we take cgroup_mutex, keeping cgroup_attach_task() from changing it |
a424316c PM |
4688 | * anyway. No need to check that tsk->cgroup != NULL, thanks to |
4689 | * the_top_cgroup_hack in cgroup_exit(), which sets an exiting tasks | |
4690 | * cgroup to top_cgroup. | |
4691 | */ | |
4692 | ||
4693 | /* TODO: Use a proper seq_file iterator */ | |
8d8b97ba | 4694 | int proc_cgroup_show(struct seq_file *m, void *v) |
a424316c PM |
4695 | { |
4696 | struct pid *pid; | |
4697 | struct task_struct *tsk; | |
4698 | char *buf; | |
4699 | int retval; | |
4700 | struct cgroupfs_root *root; | |
4701 | ||
4702 | retval = -ENOMEM; | |
4703 | buf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
4704 | if (!buf) | |
4705 | goto out; | |
4706 | ||
4707 | retval = -ESRCH; | |
4708 | pid = m->private; | |
4709 | tsk = get_pid_task(pid, PIDTYPE_PID); | |
4710 | if (!tsk) | |
4711 | goto out_free; | |
4712 | ||
4713 | retval = 0; | |
4714 | ||
4715 | mutex_lock(&cgroup_mutex); | |
4716 | ||
e5f6a860 | 4717 | for_each_active_root(root) { |
a424316c | 4718 | struct cgroup_subsys *ss; |
bd89aabc | 4719 | struct cgroup *cgrp; |
a424316c PM |
4720 | int count = 0; |
4721 | ||
2c6ab6d2 | 4722 | seq_printf(m, "%d:", root->hierarchy_id); |
a424316c PM |
4723 | for_each_subsys(root, ss) |
4724 | seq_printf(m, "%s%s", count++ ? "," : "", ss->name); | |
c6d57f33 PM |
4725 | if (strlen(root->name)) |
4726 | seq_printf(m, "%sname=%s", count ? "," : "", | |
4727 | root->name); | |
a424316c | 4728 | seq_putc(m, ':'); |
7717f7ba | 4729 | cgrp = task_cgroup_from_root(tsk, root); |
bd89aabc | 4730 | retval = cgroup_path(cgrp, buf, PAGE_SIZE); |
a424316c PM |
4731 | if (retval < 0) |
4732 | goto out_unlock; | |
4733 | seq_puts(m, buf); | |
4734 | seq_putc(m, '\n'); | |
4735 | } | |
4736 | ||
4737 | out_unlock: | |
4738 | mutex_unlock(&cgroup_mutex); | |
4739 | put_task_struct(tsk); | |
4740 | out_free: | |
4741 | kfree(buf); | |
4742 | out: | |
4743 | return retval; | |
4744 | } | |
4745 | ||
a424316c PM |
4746 | /* Display information about each subsystem and each hierarchy */ |
4747 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
4748 | { | |
4749 | int i; | |
a424316c | 4750 | |
8bab8dde | 4751 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
4752 | /* |
4753 | * ideally we don't want subsystems moving around while we do this. | |
4754 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
4755 | * subsys/hierarchy state. | |
4756 | */ | |
a424316c | 4757 | mutex_lock(&cgroup_mutex); |
a424316c PM |
4758 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
4759 | struct cgroup_subsys *ss = subsys[i]; | |
aae8aab4 BB |
4760 | if (ss == NULL) |
4761 | continue; | |
2c6ab6d2 PM |
4762 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
4763 | ss->name, ss->root->hierarchy_id, | |
8bab8dde | 4764 | ss->root->number_of_cgroups, !ss->disabled); |
a424316c PM |
4765 | } |
4766 | mutex_unlock(&cgroup_mutex); | |
4767 | return 0; | |
4768 | } | |
4769 | ||
4770 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
4771 | { | |
9dce07f1 | 4772 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
4773 | } |
4774 | ||
828c0950 | 4775 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
4776 | .open = cgroupstats_open, |
4777 | .read = seq_read, | |
4778 | .llseek = seq_lseek, | |
4779 | .release = single_release, | |
4780 | }; | |
4781 | ||
b4f48b63 PM |
4782 | /** |
4783 | * cgroup_fork - attach newly forked task to its parents cgroup. | |
a043e3b2 | 4784 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 PM |
4785 | * |
4786 | * Description: A task inherits its parent's cgroup at fork(). | |
4787 | * | |
4788 | * A pointer to the shared css_set was automatically copied in | |
4789 | * fork.c by dup_task_struct(). However, we ignore that copy, since | |
9bb71308 TH |
4790 | * it was not made under the protection of RCU or cgroup_mutex, so |
4791 | * might no longer be a valid cgroup pointer. cgroup_attach_task() might | |
4792 | * have already changed current->cgroups, allowing the previously | |
4793 | * referenced cgroup group to be removed and freed. | |
b4f48b63 PM |
4794 | * |
4795 | * At the point that cgroup_fork() is called, 'current' is the parent | |
4796 | * task, and the passed argument 'child' points to the child task. | |
4797 | */ | |
4798 | void cgroup_fork(struct task_struct *child) | |
4799 | { | |
9bb71308 | 4800 | task_lock(current); |
817929ec PM |
4801 | child->cgroups = current->cgroups; |
4802 | get_css_set(child->cgroups); | |
9bb71308 | 4803 | task_unlock(current); |
817929ec | 4804 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
4805 | } |
4806 | ||
817929ec | 4807 | /** |
a043e3b2 LZ |
4808 | * cgroup_post_fork - called on a new task after adding it to the task list |
4809 | * @child: the task in question | |
4810 | * | |
5edee61e TH |
4811 | * Adds the task to the list running through its css_set if necessary and |
4812 | * call the subsystem fork() callbacks. Has to be after the task is | |
4813 | * visible on the task list in case we race with the first call to | |
4814 | * cgroup_iter_start() - to guarantee that the new task ends up on its | |
4815 | * list. | |
a043e3b2 | 4816 | */ |
817929ec PM |
4817 | void cgroup_post_fork(struct task_struct *child) |
4818 | { | |
5edee61e TH |
4819 | int i; |
4820 | ||
3ce3230a FW |
4821 | /* |
4822 | * use_task_css_set_links is set to 1 before we walk the tasklist | |
4823 | * under the tasklist_lock and we read it here after we added the child | |
4824 | * to the tasklist under the tasklist_lock as well. If the child wasn't | |
4825 | * yet in the tasklist when we walked through it from | |
4826 | * cgroup_enable_task_cg_lists(), then use_task_css_set_links value | |
4827 | * should be visible now due to the paired locking and barriers implied | |
4828 | * by LOCK/UNLOCK: it is written before the tasklist_lock unlock | |
4829 | * in cgroup_enable_task_cg_lists() and read here after the tasklist_lock | |
4830 | * lock on fork. | |
4831 | */ | |
817929ec PM |
4832 | if (use_task_css_set_links) { |
4833 | write_lock(&css_set_lock); | |
d8783832 TH |
4834 | task_lock(child); |
4835 | if (list_empty(&child->cg_list)) | |
817929ec | 4836 | list_add(&child->cg_list, &child->cgroups->tasks); |
d8783832 | 4837 | task_unlock(child); |
817929ec PM |
4838 | write_unlock(&css_set_lock); |
4839 | } | |
5edee61e TH |
4840 | |
4841 | /* | |
4842 | * Call ss->fork(). This must happen after @child is linked on | |
4843 | * css_set; otherwise, @child might change state between ->fork() | |
4844 | * and addition to css_set. | |
4845 | */ | |
4846 | if (need_forkexit_callback) { | |
7d8e0bf5 LZ |
4847 | /* |
4848 | * fork/exit callbacks are supported only for builtin | |
4849 | * subsystems, and the builtin section of the subsys | |
4850 | * array is immutable, so we don't need to lock the | |
4851 | * subsys array here. On the other hand, modular section | |
4852 | * of the array can be freed at module unload, so we | |
4853 | * can't touch that. | |
4854 | */ | |
4855 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
5edee61e TH |
4856 | struct cgroup_subsys *ss = subsys[i]; |
4857 | ||
5edee61e TH |
4858 | if (ss->fork) |
4859 | ss->fork(child); | |
4860 | } | |
4861 | } | |
817929ec | 4862 | } |
5edee61e | 4863 | |
b4f48b63 PM |
4864 | /** |
4865 | * cgroup_exit - detach cgroup from exiting task | |
4866 | * @tsk: pointer to task_struct of exiting process | |
a043e3b2 | 4867 | * @run_callback: run exit callbacks? |
b4f48b63 PM |
4868 | * |
4869 | * Description: Detach cgroup from @tsk and release it. | |
4870 | * | |
4871 | * Note that cgroups marked notify_on_release force every task in | |
4872 | * them to take the global cgroup_mutex mutex when exiting. | |
4873 | * This could impact scaling on very large systems. Be reluctant to | |
4874 | * use notify_on_release cgroups where very high task exit scaling | |
4875 | * is required on large systems. | |
4876 | * | |
4877 | * the_top_cgroup_hack: | |
4878 | * | |
4879 | * Set the exiting tasks cgroup to the root cgroup (top_cgroup). | |
4880 | * | |
4881 | * We call cgroup_exit() while the task is still competent to | |
4882 | * handle notify_on_release(), then leave the task attached to the | |
4883 | * root cgroup in each hierarchy for the remainder of its exit. | |
4884 | * | |
4885 | * To do this properly, we would increment the reference count on | |
4886 | * top_cgroup, and near the very end of the kernel/exit.c do_exit() | |
4887 | * code we would add a second cgroup function call, to drop that | |
4888 | * reference. This would just create an unnecessary hot spot on | |
4889 | * the top_cgroup reference count, to no avail. | |
4890 | * | |
4891 | * Normally, holding a reference to a cgroup without bumping its | |
4892 | * count is unsafe. The cgroup could go away, or someone could | |
4893 | * attach us to a different cgroup, decrementing the count on | |
4894 | * the first cgroup that we never incremented. But in this case, | |
4895 | * top_cgroup isn't going away, and either task has PF_EXITING set, | |
956db3ca CW |
4896 | * which wards off any cgroup_attach_task() attempts, or task is a failed |
4897 | * fork, never visible to cgroup_attach_task. | |
b4f48b63 PM |
4898 | */ |
4899 | void cgroup_exit(struct task_struct *tsk, int run_callbacks) | |
4900 | { | |
817929ec | 4901 | struct css_set *cg; |
d41d5a01 | 4902 | int i; |
817929ec PM |
4903 | |
4904 | /* | |
4905 | * Unlink from the css_set task list if necessary. | |
4906 | * Optimistically check cg_list before taking | |
4907 | * css_set_lock | |
4908 | */ | |
4909 | if (!list_empty(&tsk->cg_list)) { | |
4910 | write_lock(&css_set_lock); | |
4911 | if (!list_empty(&tsk->cg_list)) | |
8d258797 | 4912 | list_del_init(&tsk->cg_list); |
817929ec PM |
4913 | write_unlock(&css_set_lock); |
4914 | } | |
4915 | ||
b4f48b63 PM |
4916 | /* Reassign the task to the init_css_set. */ |
4917 | task_lock(tsk); | |
817929ec PM |
4918 | cg = tsk->cgroups; |
4919 | tsk->cgroups = &init_css_set; | |
d41d5a01 PZ |
4920 | |
4921 | if (run_callbacks && need_forkexit_callback) { | |
7d8e0bf5 LZ |
4922 | /* |
4923 | * fork/exit callbacks are supported only for builtin | |
4924 | * subsystems, see cgroup_post_fork() for details. | |
4925 | */ | |
4926 | for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { | |
d41d5a01 | 4927 | struct cgroup_subsys *ss = subsys[i]; |
be45c900 | 4928 | |
d41d5a01 PZ |
4929 | if (ss->exit) { |
4930 | struct cgroup *old_cgrp = | |
4931 | rcu_dereference_raw(cg->subsys[i])->cgroup; | |
4932 | struct cgroup *cgrp = task_cgroup(tsk, i); | |
761b3ef5 | 4933 | ss->exit(cgrp, old_cgrp, tsk); |
d41d5a01 PZ |
4934 | } |
4935 | } | |
4936 | } | |
b4f48b63 | 4937 | task_unlock(tsk); |
d41d5a01 | 4938 | |
b5d646f5 | 4939 | put_css_set_taskexit(cg); |
b4f48b63 | 4940 | } |
697f4161 | 4941 | |
bd89aabc | 4942 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd PM |
4943 | { |
4944 | /* All of these checks rely on RCU to keep the cgroup | |
4945 | * structure alive */ | |
f50daa70 LZ |
4946 | if (cgroup_is_releasable(cgrp) && |
4947 | !atomic_read(&cgrp->count) && list_empty(&cgrp->children)) { | |
4948 | /* | |
4949 | * Control Group is currently removeable. If it's not | |
81a6a5cd | 4950 | * already queued for a userspace notification, queue |
f50daa70 LZ |
4951 | * it now |
4952 | */ | |
81a6a5cd | 4953 | int need_schedule_work = 0; |
f50daa70 | 4954 | |
cdcc136f | 4955 | raw_spin_lock(&release_list_lock); |
bd89aabc PM |
4956 | if (!cgroup_is_removed(cgrp) && |
4957 | list_empty(&cgrp->release_list)) { | |
4958 | list_add(&cgrp->release_list, &release_list); | |
81a6a5cd PM |
4959 | need_schedule_work = 1; |
4960 | } | |
cdcc136f | 4961 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
4962 | if (need_schedule_work) |
4963 | schedule_work(&release_agent_work); | |
4964 | } | |
4965 | } | |
4966 | ||
d7b9fff7 | 4967 | /* Caller must verify that the css is not for root cgroup */ |
28b4c27b TH |
4968 | bool __css_tryget(struct cgroup_subsys_state *css) |
4969 | { | |
e9316080 TH |
4970 | while (true) { |
4971 | int t, v; | |
28b4c27b | 4972 | |
e9316080 TH |
4973 | v = css_refcnt(css); |
4974 | t = atomic_cmpxchg(&css->refcnt, v, v + 1); | |
4975 | if (likely(t == v)) | |
28b4c27b | 4976 | return true; |
e9316080 TH |
4977 | else if (t < 0) |
4978 | return false; | |
28b4c27b | 4979 | cpu_relax(); |
e9316080 | 4980 | } |
28b4c27b TH |
4981 | } |
4982 | EXPORT_SYMBOL_GPL(__css_tryget); | |
4983 | ||
4984 | /* Caller must verify that the css is not for root cgroup */ | |
4985 | void __css_put(struct cgroup_subsys_state *css) | |
81a6a5cd | 4986 | { |
8e3bbf42 | 4987 | int v; |
28b4c27b | 4988 | |
8e3bbf42 | 4989 | v = css_unbias_refcnt(atomic_dec_return(&css->refcnt)); |
f50daa70 | 4990 | if (v == 0) |
ed957793 | 4991 | schedule_work(&css->dput_work); |
81a6a5cd | 4992 | } |
67523c48 | 4993 | EXPORT_SYMBOL_GPL(__css_put); |
81a6a5cd PM |
4994 | |
4995 | /* | |
4996 | * Notify userspace when a cgroup is released, by running the | |
4997 | * configured release agent with the name of the cgroup (path | |
4998 | * relative to the root of cgroup file system) as the argument. | |
4999 | * | |
5000 | * Most likely, this user command will try to rmdir this cgroup. | |
5001 | * | |
5002 | * This races with the possibility that some other task will be | |
5003 | * attached to this cgroup before it is removed, or that some other | |
5004 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5005 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5006 | * unused, and this cgroup will be reprieved from its death sentence, | |
5007 | * to continue to serve a useful existence. Next time it's released, | |
5008 | * we will get notified again, if it still has 'notify_on_release' set. | |
5009 | * | |
5010 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5011 | * means only wait until the task is successfully execve()'d. The | |
5012 | * separate release agent task is forked by call_usermodehelper(), | |
5013 | * then control in this thread returns here, without waiting for the | |
5014 | * release agent task. We don't bother to wait because the caller of | |
5015 | * this routine has no use for the exit status of the release agent | |
5016 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5017 | */ |
81a6a5cd PM |
5018 | static void cgroup_release_agent(struct work_struct *work) |
5019 | { | |
5020 | BUG_ON(work != &release_agent_work); | |
5021 | mutex_lock(&cgroup_mutex); | |
cdcc136f | 5022 | raw_spin_lock(&release_list_lock); |
81a6a5cd PM |
5023 | while (!list_empty(&release_list)) { |
5024 | char *argv[3], *envp[3]; | |
5025 | int i; | |
e788e066 | 5026 | char *pathbuf = NULL, *agentbuf = NULL; |
bd89aabc | 5027 | struct cgroup *cgrp = list_entry(release_list.next, |
81a6a5cd PM |
5028 | struct cgroup, |
5029 | release_list); | |
bd89aabc | 5030 | list_del_init(&cgrp->release_list); |
cdcc136f | 5031 | raw_spin_unlock(&release_list_lock); |
81a6a5cd | 5032 | pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); |
e788e066 PM |
5033 | if (!pathbuf) |
5034 | goto continue_free; | |
5035 | if (cgroup_path(cgrp, pathbuf, PAGE_SIZE) < 0) | |
5036 | goto continue_free; | |
5037 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5038 | if (!agentbuf) | |
5039 | goto continue_free; | |
81a6a5cd PM |
5040 | |
5041 | i = 0; | |
e788e066 PM |
5042 | argv[i++] = agentbuf; |
5043 | argv[i++] = pathbuf; | |
81a6a5cd PM |
5044 | argv[i] = NULL; |
5045 | ||
5046 | i = 0; | |
5047 | /* minimal command environment */ | |
5048 | envp[i++] = "HOME=/"; | |
5049 | envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5050 | envp[i] = NULL; | |
5051 | ||
5052 | /* Drop the lock while we invoke the usermode helper, | |
5053 | * since the exec could involve hitting disk and hence | |
5054 | * be a slow process */ | |
5055 | mutex_unlock(&cgroup_mutex); | |
5056 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
81a6a5cd | 5057 | mutex_lock(&cgroup_mutex); |
e788e066 PM |
5058 | continue_free: |
5059 | kfree(pathbuf); | |
5060 | kfree(agentbuf); | |
cdcc136f | 5061 | raw_spin_lock(&release_list_lock); |
81a6a5cd | 5062 | } |
cdcc136f | 5063 | raw_spin_unlock(&release_list_lock); |
81a6a5cd PM |
5064 | mutex_unlock(&cgroup_mutex); |
5065 | } | |
8bab8dde PM |
5066 | |
5067 | static int __init cgroup_disable(char *str) | |
5068 | { | |
5069 | int i; | |
5070 | char *token; | |
5071 | ||
5072 | while ((token = strsep(&str, ",")) != NULL) { | |
5073 | if (!*token) | |
5074 | continue; | |
be45c900 | 5075 | for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { |
8bab8dde PM |
5076 | struct cgroup_subsys *ss = subsys[i]; |
5077 | ||
be45c900 DW |
5078 | /* |
5079 | * cgroup_disable, being at boot time, can't | |
5080 | * know about module subsystems, so we don't | |
5081 | * worry about them. | |
5082 | */ | |
5083 | if (!ss || ss->module) | |
5084 | continue; | |
5085 | ||
8bab8dde PM |
5086 | if (!strcmp(token, ss->name)) { |
5087 | ss->disabled = 1; | |
5088 | printk(KERN_INFO "Disabling %s control group" | |
5089 | " subsystem\n", ss->name); | |
5090 | break; | |
5091 | } | |
5092 | } | |
5093 | } | |
5094 | return 1; | |
5095 | } | |
5096 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 KH |
5097 | |
5098 | /* | |
5099 | * Functons for CSS ID. | |
5100 | */ | |
5101 | ||
5102 | /* | |
5103 | *To get ID other than 0, this should be called when !cgroup_is_removed(). | |
5104 | */ | |
5105 | unsigned short css_id(struct cgroup_subsys_state *css) | |
5106 | { | |
7f0f1546 KH |
5107 | struct css_id *cssid; |
5108 | ||
5109 | /* | |
5110 | * This css_id() can return correct value when somone has refcnt | |
5111 | * on this or this is under rcu_read_lock(). Once css->id is allocated, | |
5112 | * it's unchanged until freed. | |
5113 | */ | |
28b4c27b | 5114 | cssid = rcu_dereference_check(css->id, css_refcnt(css)); |
38460b48 KH |
5115 | |
5116 | if (cssid) | |
5117 | return cssid->id; | |
5118 | return 0; | |
5119 | } | |
67523c48 | 5120 | EXPORT_SYMBOL_GPL(css_id); |
38460b48 KH |
5121 | |
5122 | unsigned short css_depth(struct cgroup_subsys_state *css) | |
5123 | { | |
7f0f1546 KH |
5124 | struct css_id *cssid; |
5125 | ||
28b4c27b | 5126 | cssid = rcu_dereference_check(css->id, css_refcnt(css)); |
38460b48 KH |
5127 | |
5128 | if (cssid) | |
5129 | return cssid->depth; | |
5130 | return 0; | |
5131 | } | |
67523c48 | 5132 | EXPORT_SYMBOL_GPL(css_depth); |
38460b48 | 5133 | |
747388d7 KH |
5134 | /** |
5135 | * css_is_ancestor - test "root" css is an ancestor of "child" | |
5136 | * @child: the css to be tested. | |
5137 | * @root: the css supporsed to be an ancestor of the child. | |
5138 | * | |
5139 | * Returns true if "root" is an ancestor of "child" in its hierarchy. Because | |
91c63734 | 5140 | * this function reads css->id, the caller must hold rcu_read_lock(). |
747388d7 KH |
5141 | * But, considering usual usage, the csses should be valid objects after test. |
5142 | * Assuming that the caller will do some action to the child if this returns | |
5143 | * returns true, the caller must take "child";s reference count. | |
5144 | * If "child" is valid object and this returns true, "root" is valid, too. | |
5145 | */ | |
5146 | ||
38460b48 | 5147 | bool css_is_ancestor(struct cgroup_subsys_state *child, |
0b7f569e | 5148 | const struct cgroup_subsys_state *root) |
38460b48 | 5149 | { |
747388d7 KH |
5150 | struct css_id *child_id; |
5151 | struct css_id *root_id; | |
38460b48 | 5152 | |
747388d7 | 5153 | child_id = rcu_dereference(child->id); |
91c63734 JW |
5154 | if (!child_id) |
5155 | return false; | |
747388d7 | 5156 | root_id = rcu_dereference(root->id); |
91c63734 JW |
5157 | if (!root_id) |
5158 | return false; | |
5159 | if (child_id->depth < root_id->depth) | |
5160 | return false; | |
5161 | if (child_id->stack[root_id->depth] != root_id->id) | |
5162 | return false; | |
5163 | return true; | |
38460b48 KH |
5164 | } |
5165 | ||
38460b48 KH |
5166 | void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) |
5167 | { | |
5168 | struct css_id *id = css->id; | |
5169 | /* When this is called before css_id initialization, id can be NULL */ | |
5170 | if (!id) | |
5171 | return; | |
5172 | ||
5173 | BUG_ON(!ss->use_id); | |
5174 | ||
5175 | rcu_assign_pointer(id->css, NULL); | |
5176 | rcu_assign_pointer(css->id, NULL); | |
42aee6c4 | 5177 | spin_lock(&ss->id_lock); |
38460b48 | 5178 | idr_remove(&ss->idr, id->id); |
42aee6c4 | 5179 | spin_unlock(&ss->id_lock); |
025cea99 | 5180 | kfree_rcu(id, rcu_head); |
38460b48 | 5181 | } |
67523c48 | 5182 | EXPORT_SYMBOL_GPL(free_css_id); |
38460b48 KH |
5183 | |
5184 | /* | |
5185 | * This is called by init or create(). Then, calls to this function are | |
5186 | * always serialized (By cgroup_mutex() at create()). | |
5187 | */ | |
5188 | ||
5189 | static struct css_id *get_new_cssid(struct cgroup_subsys *ss, int depth) | |
5190 | { | |
5191 | struct css_id *newid; | |
d228d9ec | 5192 | int ret, size; |
38460b48 KH |
5193 | |
5194 | BUG_ON(!ss->use_id); | |
5195 | ||
5196 | size = sizeof(*newid) + sizeof(unsigned short) * (depth + 1); | |
5197 | newid = kzalloc(size, GFP_KERNEL); | |
5198 | if (!newid) | |
5199 | return ERR_PTR(-ENOMEM); | |
d228d9ec TH |
5200 | |
5201 | idr_preload(GFP_KERNEL); | |
42aee6c4 | 5202 | spin_lock(&ss->id_lock); |
38460b48 | 5203 | /* Don't use 0. allocates an ID of 1-65535 */ |
d228d9ec | 5204 | ret = idr_alloc(&ss->idr, newid, 1, CSS_ID_MAX + 1, GFP_NOWAIT); |
42aee6c4 | 5205 | spin_unlock(&ss->id_lock); |
d228d9ec | 5206 | idr_preload_end(); |
38460b48 KH |
5207 | |
5208 | /* Returns error when there are no free spaces for new ID.*/ | |
d228d9ec | 5209 | if (ret < 0) |
38460b48 | 5210 | goto err_out; |
38460b48 | 5211 | |
d228d9ec | 5212 | newid->id = ret; |
38460b48 KH |
5213 | newid->depth = depth; |
5214 | return newid; | |
38460b48 KH |
5215 | err_out: |
5216 | kfree(newid); | |
d228d9ec | 5217 | return ERR_PTR(ret); |
38460b48 KH |
5218 | |
5219 | } | |
5220 | ||
e6a1105b BB |
5221 | static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, |
5222 | struct cgroup_subsys_state *rootcss) | |
38460b48 KH |
5223 | { |
5224 | struct css_id *newid; | |
38460b48 | 5225 | |
42aee6c4 | 5226 | spin_lock_init(&ss->id_lock); |
38460b48 KH |
5227 | idr_init(&ss->idr); |
5228 | ||
38460b48 KH |
5229 | newid = get_new_cssid(ss, 0); |
5230 | if (IS_ERR(newid)) | |
5231 | return PTR_ERR(newid); | |
5232 | ||
5233 | newid->stack[0] = newid->id; | |
5234 | newid->css = rootcss; | |
5235 | rootcss->id = newid; | |
5236 | return 0; | |
5237 | } | |
5238 | ||
5239 | static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent, | |
5240 | struct cgroup *child) | |
5241 | { | |
5242 | int subsys_id, i, depth = 0; | |
5243 | struct cgroup_subsys_state *parent_css, *child_css; | |
fae9c791 | 5244 | struct css_id *child_id, *parent_id; |
38460b48 KH |
5245 | |
5246 | subsys_id = ss->subsys_id; | |
5247 | parent_css = parent->subsys[subsys_id]; | |
5248 | child_css = child->subsys[subsys_id]; | |
38460b48 | 5249 | parent_id = parent_css->id; |
94b3dd0f | 5250 | depth = parent_id->depth + 1; |
38460b48 KH |
5251 | |
5252 | child_id = get_new_cssid(ss, depth); | |
5253 | if (IS_ERR(child_id)) | |
5254 | return PTR_ERR(child_id); | |
5255 | ||
5256 | for (i = 0; i < depth; i++) | |
5257 | child_id->stack[i] = parent_id->stack[i]; | |
5258 | child_id->stack[depth] = child_id->id; | |
5259 | /* | |
5260 | * child_id->css pointer will be set after this cgroup is available | |
5261 | * see cgroup_populate_dir() | |
5262 | */ | |
5263 | rcu_assign_pointer(child_css->id, child_id); | |
5264 | ||
5265 | return 0; | |
5266 | } | |
5267 | ||
5268 | /** | |
5269 | * css_lookup - lookup css by id | |
5270 | * @ss: cgroup subsys to be looked into. | |
5271 | * @id: the id | |
5272 | * | |
5273 | * Returns pointer to cgroup_subsys_state if there is valid one with id. | |
5274 | * NULL if not. Should be called under rcu_read_lock() | |
5275 | */ | |
5276 | struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) | |
5277 | { | |
5278 | struct css_id *cssid = NULL; | |
5279 | ||
5280 | BUG_ON(!ss->use_id); | |
5281 | cssid = idr_find(&ss->idr, id); | |
5282 | ||
5283 | if (unlikely(!cssid)) | |
5284 | return NULL; | |
5285 | ||
5286 | return rcu_dereference(cssid->css); | |
5287 | } | |
67523c48 | 5288 | EXPORT_SYMBOL_GPL(css_lookup); |
38460b48 | 5289 | |
e5d1367f SE |
5290 | /* |
5291 | * get corresponding css from file open on cgroupfs directory | |
5292 | */ | |
5293 | struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id) | |
5294 | { | |
5295 | struct cgroup *cgrp; | |
5296 | struct inode *inode; | |
5297 | struct cgroup_subsys_state *css; | |
5298 | ||
496ad9aa | 5299 | inode = file_inode(f); |
e5d1367f SE |
5300 | /* check in cgroup filesystem dir */ |
5301 | if (inode->i_op != &cgroup_dir_inode_operations) | |
5302 | return ERR_PTR(-EBADF); | |
5303 | ||
5304 | if (id < 0 || id >= CGROUP_SUBSYS_COUNT) | |
5305 | return ERR_PTR(-EINVAL); | |
5306 | ||
5307 | /* get cgroup */ | |
5308 | cgrp = __d_cgrp(f->f_dentry); | |
5309 | css = cgrp->subsys[id]; | |
5310 | return css ? css : ERR_PTR(-ENOENT); | |
5311 | } | |
5312 | ||
fe693435 | 5313 | #ifdef CONFIG_CGROUP_DEBUG |
92fb9748 | 5314 | static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cont) |
fe693435 PM |
5315 | { |
5316 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5317 | ||
5318 | if (!css) | |
5319 | return ERR_PTR(-ENOMEM); | |
5320 | ||
5321 | return css; | |
5322 | } | |
5323 | ||
92fb9748 | 5324 | static void debug_css_free(struct cgroup *cont) |
fe693435 PM |
5325 | { |
5326 | kfree(cont->subsys[debug_subsys_id]); | |
5327 | } | |
5328 | ||
5329 | static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) | |
5330 | { | |
5331 | return atomic_read(&cont->count); | |
5332 | } | |
5333 | ||
5334 | static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) | |
5335 | { | |
5336 | return cgroup_task_count(cont); | |
5337 | } | |
5338 | ||
5339 | static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) | |
5340 | { | |
5341 | return (u64)(unsigned long)current->cgroups; | |
5342 | } | |
5343 | ||
5344 | static u64 current_css_set_refcount_read(struct cgroup *cont, | |
5345 | struct cftype *cft) | |
5346 | { | |
5347 | u64 count; | |
5348 | ||
5349 | rcu_read_lock(); | |
5350 | count = atomic_read(¤t->cgroups->refcount); | |
5351 | rcu_read_unlock(); | |
5352 | return count; | |
5353 | } | |
5354 | ||
7717f7ba PM |
5355 | static int current_css_set_cg_links_read(struct cgroup *cont, |
5356 | struct cftype *cft, | |
5357 | struct seq_file *seq) | |
5358 | { | |
5359 | struct cg_cgroup_link *link; | |
5360 | struct css_set *cg; | |
5361 | ||
5362 | read_lock(&css_set_lock); | |
5363 | rcu_read_lock(); | |
5364 | cg = rcu_dereference(current->cgroups); | |
5365 | list_for_each_entry(link, &cg->cg_links, cg_link_list) { | |
5366 | struct cgroup *c = link->cgrp; | |
5367 | const char *name; | |
5368 | ||
5369 | if (c->dentry) | |
5370 | name = c->dentry->d_name.name; | |
5371 | else | |
5372 | name = "?"; | |
2c6ab6d2 PM |
5373 | seq_printf(seq, "Root %d group %s\n", |
5374 | c->root->hierarchy_id, name); | |
7717f7ba PM |
5375 | } |
5376 | rcu_read_unlock(); | |
5377 | read_unlock(&css_set_lock); | |
5378 | return 0; | |
5379 | } | |
5380 | ||
5381 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
5382 | static int cgroup_css_links_read(struct cgroup *cont, | |
5383 | struct cftype *cft, | |
5384 | struct seq_file *seq) | |
5385 | { | |
5386 | struct cg_cgroup_link *link; | |
5387 | ||
5388 | read_lock(&css_set_lock); | |
5389 | list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { | |
5390 | struct css_set *cg = link->cg; | |
5391 | struct task_struct *task; | |
5392 | int count = 0; | |
5393 | seq_printf(seq, "css_set %p\n", cg); | |
5394 | list_for_each_entry(task, &cg->tasks, cg_list) { | |
5395 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) { | |
5396 | seq_puts(seq, " ...\n"); | |
5397 | break; | |
5398 | } else { | |
5399 | seq_printf(seq, " task %d\n", | |
5400 | task_pid_vnr(task)); | |
5401 | } | |
5402 | } | |
5403 | } | |
5404 | read_unlock(&css_set_lock); | |
5405 | return 0; | |
5406 | } | |
5407 | ||
fe693435 PM |
5408 | static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) |
5409 | { | |
5410 | return test_bit(CGRP_RELEASABLE, &cgrp->flags); | |
5411 | } | |
5412 | ||
5413 | static struct cftype debug_files[] = { | |
5414 | { | |
5415 | .name = "cgroup_refcount", | |
5416 | .read_u64 = cgroup_refcount_read, | |
5417 | }, | |
5418 | { | |
5419 | .name = "taskcount", | |
5420 | .read_u64 = debug_taskcount_read, | |
5421 | }, | |
5422 | ||
5423 | { | |
5424 | .name = "current_css_set", | |
5425 | .read_u64 = current_css_set_read, | |
5426 | }, | |
5427 | ||
5428 | { | |
5429 | .name = "current_css_set_refcount", | |
5430 | .read_u64 = current_css_set_refcount_read, | |
5431 | }, | |
5432 | ||
7717f7ba PM |
5433 | { |
5434 | .name = "current_css_set_cg_links", | |
5435 | .read_seq_string = current_css_set_cg_links_read, | |
5436 | }, | |
5437 | ||
5438 | { | |
5439 | .name = "cgroup_css_links", | |
5440 | .read_seq_string = cgroup_css_links_read, | |
5441 | }, | |
5442 | ||
fe693435 PM |
5443 | { |
5444 | .name = "releasable", | |
5445 | .read_u64 = releasable_read, | |
5446 | }, | |
fe693435 | 5447 | |
4baf6e33 TH |
5448 | { } /* terminate */ |
5449 | }; | |
fe693435 PM |
5450 | |
5451 | struct cgroup_subsys debug_subsys = { | |
5452 | .name = "debug", | |
92fb9748 TH |
5453 | .css_alloc = debug_css_alloc, |
5454 | .css_free = debug_css_free, | |
fe693435 | 5455 | .subsys_id = debug_subsys_id, |
4baf6e33 | 5456 | .base_cftypes = debug_files, |
fe693435 PM |
5457 | }; |
5458 | #endif /* CONFIG_CGROUP_DEBUG */ |