Commit | Line | Data |
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ddbcc7e8 | 1 | /* |
ddbcc7e8 PM |
2 | * Generic process-grouping system. |
3 | * | |
4 | * Based originally on the cpuset system, extracted by Paul Menage | |
5 | * Copyright (C) 2006 Google, Inc | |
6 | * | |
0dea1168 KS |
7 | * Notifications support |
8 | * Copyright (C) 2009 Nokia Corporation | |
9 | * Author: Kirill A. Shutemov | |
10 | * | |
ddbcc7e8 PM |
11 | * Copyright notices from the original cpuset code: |
12 | * -------------------------------------------------- | |
13 | * Copyright (C) 2003 BULL SA. | |
14 | * Copyright (C) 2004-2006 Silicon Graphics, Inc. | |
15 | * | |
16 | * Portions derived from Patrick Mochel's sysfs code. | |
17 | * sysfs is Copyright (c) 2001-3 Patrick Mochel | |
18 | * | |
19 | * 2003-10-10 Written by Simon Derr. | |
20 | * 2003-10-22 Updates by Stephen Hemminger. | |
21 | * 2004 May-July Rework by Paul Jackson. | |
22 | * --------------------------------------------------- | |
23 | * | |
24 | * This file is subject to the terms and conditions of the GNU General Public | |
25 | * License. See the file COPYING in the main directory of the Linux | |
26 | * distribution for more details. | |
27 | */ | |
28 | ||
ed3d261b JP |
29 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
30 | ||
ddbcc7e8 | 31 | #include <linux/cgroup.h> |
2ce9738b | 32 | #include <linux/cred.h> |
c6d57f33 | 33 | #include <linux/ctype.h> |
ddbcc7e8 | 34 | #include <linux/errno.h> |
2ce9738b | 35 | #include <linux/init_task.h> |
ddbcc7e8 PM |
36 | #include <linux/kernel.h> |
37 | #include <linux/list.h> | |
c9482a5b | 38 | #include <linux/magic.h> |
ddbcc7e8 PM |
39 | #include <linux/mm.h> |
40 | #include <linux/mutex.h> | |
41 | #include <linux/mount.h> | |
42 | #include <linux/pagemap.h> | |
a424316c | 43 | #include <linux/proc_fs.h> |
ddbcc7e8 PM |
44 | #include <linux/rcupdate.h> |
45 | #include <linux/sched.h> | |
ddbcc7e8 | 46 | #include <linux/slab.h> |
ddbcc7e8 | 47 | #include <linux/spinlock.h> |
1ed13287 | 48 | #include <linux/percpu-rwsem.h> |
ddbcc7e8 | 49 | #include <linux/string.h> |
bbcb81d0 | 50 | #include <linux/sort.h> |
81a6a5cd | 51 | #include <linux/kmod.h> |
846c7bb0 BS |
52 | #include <linux/delayacct.h> |
53 | #include <linux/cgroupstats.h> | |
0ac801fe | 54 | #include <linux/hashtable.h> |
096b7fe0 | 55 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 56 | #include <linux/idr.h> |
d1d9fd33 | 57 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 58 | #include <linux/kthread.h> |
776f02fa | 59 | #include <linux/delay.h> |
846c7bb0 | 60 | |
60063497 | 61 | #include <linux/atomic.h> |
ddbcc7e8 | 62 | |
b1a21367 TH |
63 | /* |
64 | * pidlists linger the following amount before being destroyed. The goal | |
65 | * is avoiding frequent destruction in the middle of consecutive read calls | |
66 | * Expiring in the middle is a performance problem not a correctness one. | |
67 | * 1 sec should be enough. | |
68 | */ | |
69 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
70 | ||
8d7e6fb0 TH |
71 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
72 | MAX_CFTYPE_NAME + 2) | |
73 | ||
e25e2cbb TH |
74 | /* |
75 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
76 | * hierarchy must be performed while holding it. | |
77 | * | |
f0d9a5f1 | 78 | * css_set_lock protects task->cgroups pointer, the list of css_set |
0e1d768f | 79 | * objects, and the chain of tasks off each css_set. |
e25e2cbb | 80 | * |
0e1d768f TH |
81 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
82 | * cgroup.h can use them for lockdep annotations. | |
e25e2cbb | 83 | */ |
2219449a TH |
84 | #ifdef CONFIG_PROVE_RCU |
85 | DEFINE_MUTEX(cgroup_mutex); | |
f0d9a5f1 | 86 | DEFINE_SPINLOCK(css_set_lock); |
0e1d768f | 87 | EXPORT_SYMBOL_GPL(cgroup_mutex); |
f0d9a5f1 | 88 | EXPORT_SYMBOL_GPL(css_set_lock); |
2219449a | 89 | #else |
81a6a5cd | 90 | static DEFINE_MUTEX(cgroup_mutex); |
f0d9a5f1 | 91 | static DEFINE_SPINLOCK(css_set_lock); |
2219449a TH |
92 | #endif |
93 | ||
6fa4918d | 94 | /* |
15a4c835 TH |
95 | * Protects cgroup_idr and css_idr so that IDs can be released without |
96 | * grabbing cgroup_mutex. | |
6fa4918d TH |
97 | */ |
98 | static DEFINE_SPINLOCK(cgroup_idr_lock); | |
99 | ||
69e943b7 TH |
100 | /* |
101 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
102 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
103 | */ | |
104 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
81a6a5cd | 105 | |
1ed13287 TH |
106 | struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
107 | ||
8353da1f | 108 | #define cgroup_assert_mutex_or_rcu_locked() \ |
f78f5b90 PM |
109 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
110 | !lockdep_is_held(&cgroup_mutex), \ | |
8353da1f | 111 | "cgroup_mutex or RCU read lock required"); |
780cd8b3 | 112 | |
e5fca243 TH |
113 | /* |
114 | * cgroup destruction makes heavy use of work items and there can be a lot | |
115 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
116 | * destruction work items don't end up filling up max_active of system_wq | |
117 | * which may lead to deadlock. | |
118 | */ | |
119 | static struct workqueue_struct *cgroup_destroy_wq; | |
120 | ||
b1a21367 TH |
121 | /* |
122 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
123 | * separate workqueue as flush domain. | |
124 | */ | |
125 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
126 | ||
3ed80a62 | 127 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 128 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 129 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
130 | #include <linux/cgroup_subsys.h> |
131 | }; | |
073219e9 TH |
132 | #undef SUBSYS |
133 | ||
134 | /* array of cgroup subsystem names */ | |
135 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
136 | static const char *cgroup_subsys_name[] = { | |
ddbcc7e8 PM |
137 | #include <linux/cgroup_subsys.h> |
138 | }; | |
073219e9 | 139 | #undef SUBSYS |
ddbcc7e8 | 140 | |
49d1dc4b TH |
141 | /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
142 | #define SUBSYS(_x) \ | |
143 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ | |
144 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ | |
145 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ | |
146 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); | |
147 | #include <linux/cgroup_subsys.h> | |
148 | #undef SUBSYS | |
149 | ||
150 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, | |
151 | static struct static_key_true *cgroup_subsys_enabled_key[] = { | |
152 | #include <linux/cgroup_subsys.h> | |
153 | }; | |
154 | #undef SUBSYS | |
155 | ||
156 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, | |
157 | static struct static_key_true *cgroup_subsys_on_dfl_key[] = { | |
158 | #include <linux/cgroup_subsys.h> | |
159 | }; | |
160 | #undef SUBSYS | |
161 | ||
ddbcc7e8 | 162 | /* |
3dd06ffa | 163 | * The default hierarchy, reserved for the subsystems that are otherwise |
9871bf95 TH |
164 | * unattached - it never has more than a single cgroup, and all tasks are |
165 | * part of that cgroup. | |
ddbcc7e8 | 166 | */ |
a2dd4247 | 167 | struct cgroup_root cgrp_dfl_root; |
d0ec4230 | 168 | EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
9871bf95 | 169 | |
a2dd4247 TH |
170 | /* |
171 | * The default hierarchy always exists but is hidden until mounted for the | |
172 | * first time. This is for backward compatibility. | |
173 | */ | |
174 | static bool cgrp_dfl_root_visible; | |
ddbcc7e8 | 175 | |
a8ddc821 TH |
176 | /* |
177 | * Set by the boot param of the same name and makes subsystems with NULL | |
178 | * ->dfl_files to use ->legacy_files on the default hierarchy. | |
179 | */ | |
180 | static bool cgroup_legacy_files_on_dfl; | |
181 | ||
5533e011 | 182 | /* some controllers are not supported in the default hierarchy */ |
8ab456ac | 183 | static unsigned long cgrp_dfl_root_inhibit_ss_mask; |
5533e011 | 184 | |
ddbcc7e8 PM |
185 | /* The list of hierarchy roots */ |
186 | ||
9871bf95 TH |
187 | static LIST_HEAD(cgroup_roots); |
188 | static int cgroup_root_count; | |
ddbcc7e8 | 189 | |
3417ae1f | 190 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 191 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 192 | |
794611a1 | 193 | /* |
0cb51d71 TH |
194 | * Assign a monotonically increasing serial number to csses. It guarantees |
195 | * cgroups with bigger numbers are newer than those with smaller numbers. | |
196 | * Also, as csses are always appended to the parent's ->children list, it | |
197 | * guarantees that sibling csses are always sorted in the ascending serial | |
198 | * number order on the list. Protected by cgroup_mutex. | |
794611a1 | 199 | */ |
0cb51d71 | 200 | static u64 css_serial_nr_next = 1; |
794611a1 | 201 | |
cb4a3167 AS |
202 | /* |
203 | * These bitmask flags indicate whether tasks in the fork and exit paths have | |
204 | * fork/exit handlers to call. This avoids us having to do extra work in the | |
205 | * fork/exit path to check which subsystems have fork/exit callbacks. | |
ddbcc7e8 | 206 | */ |
cb4a3167 AS |
207 | static unsigned long have_fork_callback __read_mostly; |
208 | static unsigned long have_exit_callback __read_mostly; | |
ddbcc7e8 | 209 | |
7e47682e AS |
210 | /* Ditto for the can_fork callback. */ |
211 | static unsigned long have_canfork_callback __read_mostly; | |
212 | ||
a14c6874 TH |
213 | static struct cftype cgroup_dfl_base_files[]; |
214 | static struct cftype cgroup_legacy_base_files[]; | |
628f7cd4 | 215 | |
3dd06ffa | 216 | static int rebind_subsystems(struct cgroup_root *dst_root, |
8ab456ac | 217 | unsigned long ss_mask); |
ed27b9f7 | 218 | static void css_task_iter_advance(struct css_task_iter *it); |
42809dd4 | 219 | static int cgroup_destroy_locked(struct cgroup *cgrp); |
f63070d3 TH |
220 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
221 | bool visible); | |
9d755d33 | 222 | static void css_release(struct percpu_ref *ref); |
f8f22e53 | 223 | static void kill_css(struct cgroup_subsys_state *css); |
4df8dc90 TH |
224 | static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
225 | struct cgroup *cgrp, struct cftype cfts[], | |
2bb566cb | 226 | bool is_add); |
42809dd4 | 227 | |
fc5ed1e9 TH |
228 | /** |
229 | * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID | |
230 | * @ssid: subsys ID of interest | |
231 | * | |
232 | * cgroup_subsys_enabled() can only be used with literal subsys names which | |
233 | * is fine for individual subsystems but unsuitable for cgroup core. This | |
234 | * is slower static_key_enabled() based test indexed by @ssid. | |
235 | */ | |
236 | static bool cgroup_ssid_enabled(int ssid) | |
237 | { | |
238 | return static_key_enabled(cgroup_subsys_enabled_key[ssid]); | |
239 | } | |
240 | ||
9e10a130 TH |
241 | /** |
242 | * cgroup_on_dfl - test whether a cgroup is on the default hierarchy | |
243 | * @cgrp: the cgroup of interest | |
244 | * | |
245 | * The default hierarchy is the v2 interface of cgroup and this function | |
246 | * can be used to test whether a cgroup is on the default hierarchy for | |
247 | * cases where a subsystem should behave differnetly depending on the | |
248 | * interface version. | |
249 | * | |
250 | * The set of behaviors which change on the default hierarchy are still | |
251 | * being determined and the mount option is prefixed with __DEVEL__. | |
252 | * | |
253 | * List of changed behaviors: | |
254 | * | |
255 | * - Mount options "noprefix", "xattr", "clone_children", "release_agent" | |
256 | * and "name" are disallowed. | |
257 | * | |
258 | * - When mounting an existing superblock, mount options should match. | |
259 | * | |
260 | * - Remount is disallowed. | |
261 | * | |
262 | * - rename(2) is disallowed. | |
263 | * | |
264 | * - "tasks" is removed. Everything should be at process granularity. Use | |
265 | * "cgroup.procs" instead. | |
266 | * | |
267 | * - "cgroup.procs" is not sorted. pids will be unique unless they got | |
268 | * recycled inbetween reads. | |
269 | * | |
270 | * - "release_agent" and "notify_on_release" are removed. Replacement | |
271 | * notification mechanism will be implemented. | |
272 | * | |
273 | * - "cgroup.clone_children" is removed. | |
274 | * | |
275 | * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup | |
276 | * and its descendants contain no task; otherwise, 1. The file also | |
277 | * generates kernfs notification which can be monitored through poll and | |
278 | * [di]notify when the value of the file changes. | |
279 | * | |
280 | * - cpuset: tasks will be kept in empty cpusets when hotplug happens and | |
281 | * take masks of ancestors with non-empty cpus/mems, instead of being | |
282 | * moved to an ancestor. | |
283 | * | |
284 | * - cpuset: a task can be moved into an empty cpuset, and again it takes | |
285 | * masks of ancestors. | |
286 | * | |
287 | * - memcg: use_hierarchy is on by default and the cgroup file for the flag | |
288 | * is not created. | |
289 | * | |
290 | * - blkcg: blk-throttle becomes properly hierarchical. | |
291 | * | |
292 | * - debug: disallowed on the default hierarchy. | |
293 | */ | |
294 | static bool cgroup_on_dfl(const struct cgroup *cgrp) | |
295 | { | |
296 | return cgrp->root == &cgrp_dfl_root; | |
297 | } | |
298 | ||
6fa4918d TH |
299 | /* IDR wrappers which synchronize using cgroup_idr_lock */ |
300 | static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, | |
301 | gfp_t gfp_mask) | |
302 | { | |
303 | int ret; | |
304 | ||
305 | idr_preload(gfp_mask); | |
54504e97 | 306 | spin_lock_bh(&cgroup_idr_lock); |
cf780b7d | 307 | ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_WAIT); |
54504e97 | 308 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
309 | idr_preload_end(); |
310 | return ret; | |
311 | } | |
312 | ||
313 | static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) | |
314 | { | |
315 | void *ret; | |
316 | ||
54504e97 | 317 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 318 | ret = idr_replace(idr, ptr, id); |
54504e97 | 319 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
320 | return ret; |
321 | } | |
322 | ||
323 | static void cgroup_idr_remove(struct idr *idr, int id) | |
324 | { | |
54504e97 | 325 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 326 | idr_remove(idr, id); |
54504e97 | 327 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
328 | } |
329 | ||
d51f39b0 TH |
330 | static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
331 | { | |
332 | struct cgroup_subsys_state *parent_css = cgrp->self.parent; | |
333 | ||
334 | if (parent_css) | |
335 | return container_of(parent_css, struct cgroup, self); | |
336 | return NULL; | |
337 | } | |
338 | ||
95109b62 TH |
339 | /** |
340 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
341 | * @cgrp: the cgroup of interest | |
9d800df1 | 342 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
95109b62 | 343 | * |
ca8bdcaf TH |
344 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
345 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
346 | * the caller is responsible for pinning the returned css if it wants to | |
347 | * keep accessing it outside the said locks. This function may return | |
348 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
349 | */ |
350 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 351 | struct cgroup_subsys *ss) |
95109b62 | 352 | { |
ca8bdcaf | 353 | if (ss) |
aec25020 | 354 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 | 355 | lockdep_is_held(&cgroup_mutex)); |
ca8bdcaf | 356 | else |
9d800df1 | 357 | return &cgrp->self; |
95109b62 | 358 | } |
42809dd4 | 359 | |
aec3dfcb TH |
360 | /** |
361 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem | |
362 | * @cgrp: the cgroup of interest | |
9d800df1 | 363 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
aec3dfcb | 364 | * |
d0f702e6 | 365 | * Similar to cgroup_css() but returns the effective css, which is defined |
aec3dfcb TH |
366 | * as the matching css of the nearest ancestor including self which has @ss |
367 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this | |
368 | * function is guaranteed to return non-NULL css. | |
369 | */ | |
370 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, | |
371 | struct cgroup_subsys *ss) | |
372 | { | |
373 | lockdep_assert_held(&cgroup_mutex); | |
374 | ||
375 | if (!ss) | |
9d800df1 | 376 | return &cgrp->self; |
aec3dfcb TH |
377 | |
378 | if (!(cgrp->root->subsys_mask & (1 << ss->id))) | |
379 | return NULL; | |
380 | ||
eeecbd19 TH |
381 | /* |
382 | * This function is used while updating css associations and thus | |
383 | * can't test the csses directly. Use ->child_subsys_mask. | |
384 | */ | |
d51f39b0 TH |
385 | while (cgroup_parent(cgrp) && |
386 | !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id))) | |
387 | cgrp = cgroup_parent(cgrp); | |
aec3dfcb TH |
388 | |
389 | return cgroup_css(cgrp, ss); | |
95109b62 | 390 | } |
42809dd4 | 391 | |
eeecbd19 TH |
392 | /** |
393 | * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem | |
394 | * @cgrp: the cgroup of interest | |
395 | * @ss: the subsystem of interest | |
396 | * | |
397 | * Find and get the effective css of @cgrp for @ss. The effective css is | |
398 | * defined as the matching css of the nearest ancestor including self which | |
399 | * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, | |
400 | * the root css is returned, so this function always returns a valid css. | |
401 | * The returned css must be put using css_put(). | |
402 | */ | |
403 | struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, | |
404 | struct cgroup_subsys *ss) | |
405 | { | |
406 | struct cgroup_subsys_state *css; | |
407 | ||
408 | rcu_read_lock(); | |
409 | ||
410 | do { | |
411 | css = cgroup_css(cgrp, ss); | |
412 | ||
413 | if (css && css_tryget_online(css)) | |
414 | goto out_unlock; | |
415 | cgrp = cgroup_parent(cgrp); | |
416 | } while (cgrp); | |
417 | ||
418 | css = init_css_set.subsys[ss->id]; | |
419 | css_get(css); | |
420 | out_unlock: | |
421 | rcu_read_unlock(); | |
422 | return css; | |
423 | } | |
424 | ||
ddbcc7e8 | 425 | /* convenient tests for these bits */ |
54766d4a | 426 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 427 | { |
184faf32 | 428 | return !(cgrp->self.flags & CSS_ONLINE); |
ddbcc7e8 PM |
429 | } |
430 | ||
052c3f3a TH |
431 | static void cgroup_get(struct cgroup *cgrp) |
432 | { | |
433 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); | |
434 | css_get(&cgrp->self); | |
435 | } | |
436 | ||
437 | static bool cgroup_tryget(struct cgroup *cgrp) | |
438 | { | |
439 | return css_tryget(&cgrp->self); | |
440 | } | |
441 | ||
442 | static void cgroup_put(struct cgroup *cgrp) | |
443 | { | |
444 | css_put(&cgrp->self); | |
445 | } | |
446 | ||
b4168640 | 447 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
59f5296b | 448 | { |
2bd59d48 | 449 | struct cgroup *cgrp = of->kn->parent->priv; |
b4168640 | 450 | struct cftype *cft = of_cft(of); |
2bd59d48 TH |
451 | |
452 | /* | |
453 | * This is open and unprotected implementation of cgroup_css(). | |
454 | * seq_css() is only called from a kernfs file operation which has | |
455 | * an active reference on the file. Because all the subsystem | |
456 | * files are drained before a css is disassociated with a cgroup, | |
457 | * the matching css from the cgroup's subsys table is guaranteed to | |
458 | * be and stay valid until the enclosing operation is complete. | |
459 | */ | |
460 | if (cft->ss) | |
461 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
462 | else | |
9d800df1 | 463 | return &cgrp->self; |
59f5296b | 464 | } |
b4168640 | 465 | EXPORT_SYMBOL_GPL(of_css); |
59f5296b | 466 | |
78574cf9 LZ |
467 | /** |
468 | * cgroup_is_descendant - test ancestry | |
469 | * @cgrp: the cgroup to be tested | |
470 | * @ancestor: possible ancestor of @cgrp | |
471 | * | |
472 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
473 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
474 | * and @ancestor are accessible. | |
475 | */ | |
476 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
477 | { | |
478 | while (cgrp) { | |
479 | if (cgrp == ancestor) | |
480 | return true; | |
d51f39b0 | 481 | cgrp = cgroup_parent(cgrp); |
78574cf9 LZ |
482 | } |
483 | return false; | |
484 | } | |
ddbcc7e8 | 485 | |
e9685a03 | 486 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 487 | { |
bd89aabc | 488 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
489 | } |
490 | ||
1c6727af TH |
491 | /** |
492 | * for_each_css - iterate all css's of a cgroup | |
493 | * @css: the iteration cursor | |
494 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
495 | * @cgrp: the target cgroup to iterate css's of | |
496 | * | |
aec3dfcb | 497 | * Should be called under cgroup_[tree_]mutex. |
1c6727af TH |
498 | */ |
499 | #define for_each_css(css, ssid, cgrp) \ | |
500 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
501 | if (!((css) = rcu_dereference_check( \ | |
502 | (cgrp)->subsys[(ssid)], \ | |
503 | lockdep_is_held(&cgroup_mutex)))) { } \ | |
504 | else | |
505 | ||
aec3dfcb TH |
506 | /** |
507 | * for_each_e_css - iterate all effective css's of a cgroup | |
508 | * @css: the iteration cursor | |
509 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
510 | * @cgrp: the target cgroup to iterate css's of | |
511 | * | |
512 | * Should be called under cgroup_[tree_]mutex. | |
513 | */ | |
514 | #define for_each_e_css(css, ssid, cgrp) \ | |
515 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
516 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ | |
517 | ; \ | |
518 | else | |
519 | ||
30159ec7 | 520 | /** |
3ed80a62 | 521 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 522 | * @ss: the iteration cursor |
780cd8b3 | 523 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 524 | */ |
780cd8b3 | 525 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
526 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
527 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 528 | |
cb4a3167 AS |
529 | /** |
530 | * for_each_subsys_which - filter for_each_subsys with a bitmask | |
531 | * @ss: the iteration cursor | |
532 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end | |
533 | * @ss_maskp: a pointer to the bitmask | |
534 | * | |
535 | * The block will only run for cases where the ssid-th bit (1 << ssid) of | |
536 | * mask is set to 1. | |
537 | */ | |
538 | #define for_each_subsys_which(ss, ssid, ss_maskp) \ | |
539 | if (!CGROUP_SUBSYS_COUNT) /* to avoid spurious gcc warning */ \ | |
4a705c5c | 540 | (ssid) = 0; \ |
cb4a3167 AS |
541 | else \ |
542 | for_each_set_bit(ssid, ss_maskp, CGROUP_SUBSYS_COUNT) \ | |
543 | if (((ss) = cgroup_subsys[ssid]) && false) \ | |
544 | break; \ | |
545 | else | |
546 | ||
985ed670 TH |
547 | /* iterate across the hierarchies */ |
548 | #define for_each_root(root) \ | |
5549c497 | 549 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 550 | |
f8f22e53 TH |
551 | /* iterate over child cgrps, lock should be held throughout iteration */ |
552 | #define cgroup_for_each_live_child(child, cgrp) \ | |
d5c419b6 | 553 | list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
8353da1f | 554 | if (({ lockdep_assert_held(&cgroup_mutex); \ |
f8f22e53 TH |
555 | cgroup_is_dead(child); })) \ |
556 | ; \ | |
557 | else | |
7ae1bad9 | 558 | |
81a6a5cd | 559 | static void cgroup_release_agent(struct work_struct *work); |
bd89aabc | 560 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 561 | |
69d0206c TH |
562 | /* |
563 | * A cgroup can be associated with multiple css_sets as different tasks may | |
564 | * belong to different cgroups on different hierarchies. In the other | |
565 | * direction, a css_set is naturally associated with multiple cgroups. | |
566 | * This M:N relationship is represented by the following link structure | |
567 | * which exists for each association and allows traversing the associations | |
568 | * from both sides. | |
569 | */ | |
570 | struct cgrp_cset_link { | |
571 | /* the cgroup and css_set this link associates */ | |
572 | struct cgroup *cgrp; | |
573 | struct css_set *cset; | |
574 | ||
575 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
576 | struct list_head cset_link; | |
577 | ||
578 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
579 | struct list_head cgrp_link; | |
817929ec PM |
580 | }; |
581 | ||
172a2c06 TH |
582 | /* |
583 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
584 | * hierarchies being mounted. It contains a pointer to the root state |
585 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
586 | * reference-counted, to improve performance when child cgroups | |
587 | * haven't been created. | |
588 | */ | |
5024ae29 | 589 | struct css_set init_css_set = { |
172a2c06 TH |
590 | .refcount = ATOMIC_INIT(1), |
591 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
592 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
593 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
594 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
595 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
ed27b9f7 | 596 | .task_iters = LIST_HEAD_INIT(init_css_set.task_iters), |
172a2c06 | 597 | }; |
817929ec | 598 | |
172a2c06 | 599 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 600 | |
0de0942d TH |
601 | /** |
602 | * css_set_populated - does a css_set contain any tasks? | |
603 | * @cset: target css_set | |
604 | */ | |
605 | static bool css_set_populated(struct css_set *cset) | |
606 | { | |
f0d9a5f1 | 607 | lockdep_assert_held(&css_set_lock); |
0de0942d TH |
608 | |
609 | return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks); | |
610 | } | |
611 | ||
842b597e TH |
612 | /** |
613 | * cgroup_update_populated - updated populated count of a cgroup | |
614 | * @cgrp: the target cgroup | |
615 | * @populated: inc or dec populated count | |
616 | * | |
0de0942d TH |
617 | * One of the css_sets associated with @cgrp is either getting its first |
618 | * task or losing the last. Update @cgrp->populated_cnt accordingly. The | |
619 | * count is propagated towards root so that a given cgroup's populated_cnt | |
620 | * is zero iff the cgroup and all its descendants don't contain any tasks. | |
842b597e TH |
621 | * |
622 | * @cgrp's interface file "cgroup.populated" is zero if | |
623 | * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt | |
624 | * changes from or to zero, userland is notified that the content of the | |
625 | * interface file has changed. This can be used to detect when @cgrp and | |
626 | * its descendants become populated or empty. | |
627 | */ | |
628 | static void cgroup_update_populated(struct cgroup *cgrp, bool populated) | |
629 | { | |
f0d9a5f1 | 630 | lockdep_assert_held(&css_set_lock); |
842b597e TH |
631 | |
632 | do { | |
633 | bool trigger; | |
634 | ||
635 | if (populated) | |
636 | trigger = !cgrp->populated_cnt++; | |
637 | else | |
638 | trigger = !--cgrp->populated_cnt; | |
639 | ||
640 | if (!trigger) | |
641 | break; | |
642 | ||
ad2ed2b3 | 643 | check_for_release(cgrp); |
6f60eade TH |
644 | cgroup_file_notify(&cgrp->events_file); |
645 | ||
d51f39b0 | 646 | cgrp = cgroup_parent(cgrp); |
842b597e TH |
647 | } while (cgrp); |
648 | } | |
649 | ||
0de0942d TH |
650 | /** |
651 | * css_set_update_populated - update populated state of a css_set | |
652 | * @cset: target css_set | |
653 | * @populated: whether @cset is populated or depopulated | |
654 | * | |
655 | * @cset is either getting the first task or losing the last. Update the | |
656 | * ->populated_cnt of all associated cgroups accordingly. | |
657 | */ | |
658 | static void css_set_update_populated(struct css_set *cset, bool populated) | |
659 | { | |
660 | struct cgrp_cset_link *link; | |
661 | ||
f0d9a5f1 | 662 | lockdep_assert_held(&css_set_lock); |
0de0942d TH |
663 | |
664 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) | |
665 | cgroup_update_populated(link->cgrp, populated); | |
666 | } | |
667 | ||
f6d7d049 TH |
668 | /** |
669 | * css_set_move_task - move a task from one css_set to another | |
670 | * @task: task being moved | |
671 | * @from_cset: css_set @task currently belongs to (may be NULL) | |
672 | * @to_cset: new css_set @task is being moved to (may be NULL) | |
673 | * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks | |
674 | * | |
675 | * Move @task from @from_cset to @to_cset. If @task didn't belong to any | |
676 | * css_set, @from_cset can be NULL. If @task is being disassociated | |
677 | * instead of moved, @to_cset can be NULL. | |
678 | * | |
ed27b9f7 TH |
679 | * This function automatically handles populated_cnt updates and |
680 | * css_task_iter adjustments but the caller is responsible for managing | |
681 | * @from_cset and @to_cset's reference counts. | |
f6d7d049 TH |
682 | */ |
683 | static void css_set_move_task(struct task_struct *task, | |
684 | struct css_set *from_cset, struct css_set *to_cset, | |
685 | bool use_mg_tasks) | |
686 | { | |
f0d9a5f1 | 687 | lockdep_assert_held(&css_set_lock); |
f6d7d049 TH |
688 | |
689 | if (from_cset) { | |
ed27b9f7 TH |
690 | struct css_task_iter *it, *pos; |
691 | ||
f6d7d049 | 692 | WARN_ON_ONCE(list_empty(&task->cg_list)); |
ed27b9f7 TH |
693 | |
694 | /* | |
695 | * @task is leaving, advance task iterators which are | |
696 | * pointing to it so that they can resume at the next | |
697 | * position. Advancing an iterator might remove it from | |
698 | * the list, use safe walk. See css_task_iter_advance*() | |
699 | * for details. | |
700 | */ | |
701 | list_for_each_entry_safe(it, pos, &from_cset->task_iters, | |
702 | iters_node) | |
703 | if (it->task_pos == &task->cg_list) | |
704 | css_task_iter_advance(it); | |
705 | ||
f6d7d049 TH |
706 | list_del_init(&task->cg_list); |
707 | if (!css_set_populated(from_cset)) | |
708 | css_set_update_populated(from_cset, false); | |
709 | } else { | |
710 | WARN_ON_ONCE(!list_empty(&task->cg_list)); | |
711 | } | |
712 | ||
713 | if (to_cset) { | |
714 | /* | |
715 | * We are synchronized through cgroup_threadgroup_rwsem | |
716 | * against PF_EXITING setting such that we can't race | |
717 | * against cgroup_exit() changing the css_set to | |
718 | * init_css_set and dropping the old one. | |
719 | */ | |
720 | WARN_ON_ONCE(task->flags & PF_EXITING); | |
721 | ||
722 | if (!css_set_populated(to_cset)) | |
723 | css_set_update_populated(to_cset, true); | |
724 | rcu_assign_pointer(task->cgroups, to_cset); | |
725 | list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks : | |
726 | &to_cset->tasks); | |
727 | } | |
728 | } | |
729 | ||
7717f7ba PM |
730 | /* |
731 | * hash table for cgroup groups. This improves the performance to find | |
732 | * an existing css_set. This hash doesn't (currently) take into | |
733 | * account cgroups in empty hierarchies. | |
734 | */ | |
472b1053 | 735 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 736 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 737 | |
0ac801fe | 738 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 739 | { |
0ac801fe | 740 | unsigned long key = 0UL; |
30159ec7 TH |
741 | struct cgroup_subsys *ss; |
742 | int i; | |
472b1053 | 743 | |
30159ec7 | 744 | for_each_subsys(ss, i) |
0ac801fe LZ |
745 | key += (unsigned long)css[i]; |
746 | key = (key >> 16) ^ key; | |
472b1053 | 747 | |
0ac801fe | 748 | return key; |
472b1053 LZ |
749 | } |
750 | ||
a25eb52e | 751 | static void put_css_set_locked(struct css_set *cset) |
b4f48b63 | 752 | { |
69d0206c | 753 | struct cgrp_cset_link *link, *tmp_link; |
2d8f243a TH |
754 | struct cgroup_subsys *ss; |
755 | int ssid; | |
5abb8855 | 756 | |
f0d9a5f1 | 757 | lockdep_assert_held(&css_set_lock); |
89c5509b TH |
758 | |
759 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 760 | return; |
81a6a5cd | 761 | |
2c6ab6d2 | 762 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
2d8f243a TH |
763 | for_each_subsys(ss, ssid) |
764 | list_del(&cset->e_cset_node[ssid]); | |
5abb8855 | 765 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
766 | css_set_count--; |
767 | ||
69d0206c | 768 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
69d0206c TH |
769 | list_del(&link->cset_link); |
770 | list_del(&link->cgrp_link); | |
2ceb231b TH |
771 | if (cgroup_parent(link->cgrp)) |
772 | cgroup_put(link->cgrp); | |
2c6ab6d2 | 773 | kfree(link); |
81a6a5cd | 774 | } |
2c6ab6d2 | 775 | |
5abb8855 | 776 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
777 | } |
778 | ||
a25eb52e | 779 | static void put_css_set(struct css_set *cset) |
89c5509b TH |
780 | { |
781 | /* | |
782 | * Ensure that the refcount doesn't hit zero while any readers | |
783 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
784 | * rwlock | |
785 | */ | |
786 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
787 | return; | |
788 | ||
f0d9a5f1 | 789 | spin_lock_bh(&css_set_lock); |
a25eb52e | 790 | put_css_set_locked(cset); |
f0d9a5f1 | 791 | spin_unlock_bh(&css_set_lock); |
89c5509b TH |
792 | } |
793 | ||
817929ec PM |
794 | /* |
795 | * refcounted get/put for css_set objects | |
796 | */ | |
5abb8855 | 797 | static inline void get_css_set(struct css_set *cset) |
817929ec | 798 | { |
5abb8855 | 799 | atomic_inc(&cset->refcount); |
817929ec PM |
800 | } |
801 | ||
b326f9d0 | 802 | /** |
7717f7ba | 803 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
804 | * @cset: candidate css_set being tested |
805 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
806 | * @new_cgrp: cgroup that's being entered by the task |
807 | * @template: desired set of css pointers in css_set (pre-calculated) | |
808 | * | |
6f4b7e63 | 809 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
810 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
811 | */ | |
5abb8855 TH |
812 | static bool compare_css_sets(struct css_set *cset, |
813 | struct css_set *old_cset, | |
7717f7ba PM |
814 | struct cgroup *new_cgrp, |
815 | struct cgroup_subsys_state *template[]) | |
816 | { | |
817 | struct list_head *l1, *l2; | |
818 | ||
aec3dfcb TH |
819 | /* |
820 | * On the default hierarchy, there can be csets which are | |
821 | * associated with the same set of cgroups but different csses. | |
822 | * Let's first ensure that csses match. | |
823 | */ | |
824 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) | |
7717f7ba | 825 | return false; |
7717f7ba PM |
826 | |
827 | /* | |
828 | * Compare cgroup pointers in order to distinguish between | |
aec3dfcb TH |
829 | * different cgroups in hierarchies. As different cgroups may |
830 | * share the same effective css, this comparison is always | |
831 | * necessary. | |
7717f7ba | 832 | */ |
69d0206c TH |
833 | l1 = &cset->cgrp_links; |
834 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 835 | while (1) { |
69d0206c | 836 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 837 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
838 | |
839 | l1 = l1->next; | |
840 | l2 = l2->next; | |
841 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
842 | if (l1 == &cset->cgrp_links) { |
843 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
844 | break; |
845 | } else { | |
69d0206c | 846 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
847 | } |
848 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
849 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
850 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
851 | cgrp1 = link1->cgrp; | |
852 | cgrp2 = link2->cgrp; | |
7717f7ba | 853 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 854 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
855 | |
856 | /* | |
857 | * If this hierarchy is the hierarchy of the cgroup | |
858 | * that's changing, then we need to check that this | |
859 | * css_set points to the new cgroup; if it's any other | |
860 | * hierarchy, then this css_set should point to the | |
861 | * same cgroup as the old css_set. | |
862 | */ | |
5abb8855 TH |
863 | if (cgrp1->root == new_cgrp->root) { |
864 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
865 | return false; |
866 | } else { | |
5abb8855 | 867 | if (cgrp1 != cgrp2) |
7717f7ba PM |
868 | return false; |
869 | } | |
870 | } | |
871 | return true; | |
872 | } | |
873 | ||
b326f9d0 TH |
874 | /** |
875 | * find_existing_css_set - init css array and find the matching css_set | |
876 | * @old_cset: the css_set that we're using before the cgroup transition | |
877 | * @cgrp: the cgroup that we're moving into | |
878 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 879 | */ |
5abb8855 TH |
880 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
881 | struct cgroup *cgrp, | |
882 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 883 | { |
3dd06ffa | 884 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 885 | struct cgroup_subsys *ss; |
5abb8855 | 886 | struct css_set *cset; |
0ac801fe | 887 | unsigned long key; |
b326f9d0 | 888 | int i; |
817929ec | 889 | |
aae8aab4 BB |
890 | /* |
891 | * Build the set of subsystem state objects that we want to see in the | |
892 | * new css_set. while subsystems can change globally, the entries here | |
893 | * won't change, so no need for locking. | |
894 | */ | |
30159ec7 | 895 | for_each_subsys(ss, i) { |
f392e51c | 896 | if (root->subsys_mask & (1UL << i)) { |
aec3dfcb TH |
897 | /* |
898 | * @ss is in this hierarchy, so we want the | |
899 | * effective css from @cgrp. | |
900 | */ | |
901 | template[i] = cgroup_e_css(cgrp, ss); | |
817929ec | 902 | } else { |
aec3dfcb TH |
903 | /* |
904 | * @ss is not in this hierarchy, so we don't want | |
905 | * to change the css. | |
906 | */ | |
5abb8855 | 907 | template[i] = old_cset->subsys[i]; |
817929ec PM |
908 | } |
909 | } | |
910 | ||
0ac801fe | 911 | key = css_set_hash(template); |
5abb8855 TH |
912 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
913 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
914 | continue; |
915 | ||
916 | /* This css_set matches what we need */ | |
5abb8855 | 917 | return cset; |
472b1053 | 918 | } |
817929ec PM |
919 | |
920 | /* No existing cgroup group matched */ | |
921 | return NULL; | |
922 | } | |
923 | ||
69d0206c | 924 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 925 | { |
69d0206c | 926 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 927 | |
69d0206c TH |
928 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
929 | list_del(&link->cset_link); | |
36553434 LZ |
930 | kfree(link); |
931 | } | |
932 | } | |
933 | ||
69d0206c TH |
934 | /** |
935 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
936 | * @count: the number of links to allocate | |
937 | * @tmp_links: list_head the allocated links are put on | |
938 | * | |
939 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
940 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 941 | */ |
69d0206c | 942 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 943 | { |
69d0206c | 944 | struct cgrp_cset_link *link; |
817929ec | 945 | int i; |
69d0206c TH |
946 | |
947 | INIT_LIST_HEAD(tmp_links); | |
948 | ||
817929ec | 949 | for (i = 0; i < count; i++) { |
f4f4be2b | 950 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 951 | if (!link) { |
69d0206c | 952 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
953 | return -ENOMEM; |
954 | } | |
69d0206c | 955 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
956 | } |
957 | return 0; | |
958 | } | |
959 | ||
c12f65d4 LZ |
960 | /** |
961 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 962 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 963 | * @cset: the css_set to be linked |
c12f65d4 LZ |
964 | * @cgrp: the destination cgroup |
965 | */ | |
69d0206c TH |
966 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
967 | struct cgroup *cgrp) | |
c12f65d4 | 968 | { |
69d0206c | 969 | struct cgrp_cset_link *link; |
c12f65d4 | 970 | |
69d0206c | 971 | BUG_ON(list_empty(tmp_links)); |
6803c006 TH |
972 | |
973 | if (cgroup_on_dfl(cgrp)) | |
974 | cset->dfl_cgrp = cgrp; | |
975 | ||
69d0206c TH |
976 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
977 | link->cset = cset; | |
7717f7ba | 978 | link->cgrp = cgrp; |
842b597e | 979 | |
7717f7ba | 980 | /* |
389b9c1b TH |
981 | * Always add links to the tail of the lists so that the lists are |
982 | * in choronological order. | |
7717f7ba | 983 | */ |
389b9c1b | 984 | list_move_tail(&link->cset_link, &cgrp->cset_links); |
69d0206c | 985 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
2ceb231b TH |
986 | |
987 | if (cgroup_parent(cgrp)) | |
988 | cgroup_get(cgrp); | |
c12f65d4 LZ |
989 | } |
990 | ||
b326f9d0 TH |
991 | /** |
992 | * find_css_set - return a new css_set with one cgroup updated | |
993 | * @old_cset: the baseline css_set | |
994 | * @cgrp: the cgroup to be updated | |
995 | * | |
996 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
997 | * substituted into the appropriate hierarchy. | |
817929ec | 998 | */ |
5abb8855 TH |
999 | static struct css_set *find_css_set(struct css_set *old_cset, |
1000 | struct cgroup *cgrp) | |
817929ec | 1001 | { |
b326f9d0 | 1002 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 1003 | struct css_set *cset; |
69d0206c TH |
1004 | struct list_head tmp_links; |
1005 | struct cgrp_cset_link *link; | |
2d8f243a | 1006 | struct cgroup_subsys *ss; |
0ac801fe | 1007 | unsigned long key; |
2d8f243a | 1008 | int ssid; |
472b1053 | 1009 | |
b326f9d0 TH |
1010 | lockdep_assert_held(&cgroup_mutex); |
1011 | ||
817929ec PM |
1012 | /* First see if we already have a cgroup group that matches |
1013 | * the desired set */ | |
f0d9a5f1 | 1014 | spin_lock_bh(&css_set_lock); |
5abb8855 TH |
1015 | cset = find_existing_css_set(old_cset, cgrp, template); |
1016 | if (cset) | |
1017 | get_css_set(cset); | |
f0d9a5f1 | 1018 | spin_unlock_bh(&css_set_lock); |
817929ec | 1019 | |
5abb8855 TH |
1020 | if (cset) |
1021 | return cset; | |
817929ec | 1022 | |
f4f4be2b | 1023 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 1024 | if (!cset) |
817929ec PM |
1025 | return NULL; |
1026 | ||
69d0206c | 1027 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 1028 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 1029 | kfree(cset); |
817929ec PM |
1030 | return NULL; |
1031 | } | |
1032 | ||
5abb8855 | 1033 | atomic_set(&cset->refcount, 1); |
69d0206c | 1034 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 1035 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 1036 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 1037 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 1038 | INIT_LIST_HEAD(&cset->mg_node); |
ed27b9f7 | 1039 | INIT_LIST_HEAD(&cset->task_iters); |
5abb8855 | 1040 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
1041 | |
1042 | /* Copy the set of subsystem state objects generated in | |
1043 | * find_existing_css_set() */ | |
5abb8855 | 1044 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 1045 | |
f0d9a5f1 | 1046 | spin_lock_bh(&css_set_lock); |
817929ec | 1047 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 1048 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 1049 | struct cgroup *c = link->cgrp; |
69d0206c | 1050 | |
7717f7ba PM |
1051 | if (c->root == cgrp->root) |
1052 | c = cgrp; | |
69d0206c | 1053 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 1054 | } |
817929ec | 1055 | |
69d0206c | 1056 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 1057 | |
817929ec | 1058 | css_set_count++; |
472b1053 | 1059 | |
2d8f243a | 1060 | /* Add @cset to the hash table */ |
5abb8855 TH |
1061 | key = css_set_hash(cset->subsys); |
1062 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 1063 | |
2d8f243a TH |
1064 | for_each_subsys(ss, ssid) |
1065 | list_add_tail(&cset->e_cset_node[ssid], | |
1066 | &cset->subsys[ssid]->cgroup->e_csets[ssid]); | |
1067 | ||
f0d9a5f1 | 1068 | spin_unlock_bh(&css_set_lock); |
817929ec | 1069 | |
5abb8855 | 1070 | return cset; |
b4f48b63 PM |
1071 | } |
1072 | ||
3dd06ffa | 1073 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 1074 | { |
3dd06ffa | 1075 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 1076 | |
3dd06ffa | 1077 | return root_cgrp->root; |
2bd59d48 TH |
1078 | } |
1079 | ||
3dd06ffa | 1080 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
1081 | { |
1082 | int id; | |
1083 | ||
1084 | lockdep_assert_held(&cgroup_mutex); | |
1085 | ||
985ed670 | 1086 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
1087 | if (id < 0) |
1088 | return id; | |
1089 | ||
1090 | root->hierarchy_id = id; | |
1091 | return 0; | |
1092 | } | |
1093 | ||
3dd06ffa | 1094 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
1095 | { |
1096 | lockdep_assert_held(&cgroup_mutex); | |
1097 | ||
1098 | if (root->hierarchy_id) { | |
1099 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
1100 | root->hierarchy_id = 0; | |
1101 | } | |
1102 | } | |
1103 | ||
3dd06ffa | 1104 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
1105 | { |
1106 | if (root) { | |
d0f702e6 | 1107 | /* hierarchy ID should already have been released */ |
f2e85d57 TH |
1108 | WARN_ON_ONCE(root->hierarchy_id); |
1109 | ||
1110 | idr_destroy(&root->cgroup_idr); | |
1111 | kfree(root); | |
1112 | } | |
1113 | } | |
1114 | ||
3dd06ffa | 1115 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 1116 | { |
3dd06ffa | 1117 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 1118 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 1119 | |
2bd59d48 | 1120 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 1121 | |
776f02fa | 1122 | BUG_ON(atomic_read(&root->nr_cgrps)); |
d5c419b6 | 1123 | BUG_ON(!list_empty(&cgrp->self.children)); |
f2e85d57 | 1124 | |
f2e85d57 | 1125 | /* Rebind all subsystems back to the default hierarchy */ |
f392e51c | 1126 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); |
7717f7ba | 1127 | |
7717f7ba | 1128 | /* |
f2e85d57 TH |
1129 | * Release all the links from cset_links to this hierarchy's |
1130 | * root cgroup | |
7717f7ba | 1131 | */ |
f0d9a5f1 | 1132 | spin_lock_bh(&css_set_lock); |
f2e85d57 TH |
1133 | |
1134 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
1135 | list_del(&link->cset_link); | |
1136 | list_del(&link->cgrp_link); | |
1137 | kfree(link); | |
1138 | } | |
f0d9a5f1 TH |
1139 | |
1140 | spin_unlock_bh(&css_set_lock); | |
f2e85d57 TH |
1141 | |
1142 | if (!list_empty(&root->root_list)) { | |
1143 | list_del(&root->root_list); | |
1144 | cgroup_root_count--; | |
1145 | } | |
1146 | ||
1147 | cgroup_exit_root_id(root); | |
1148 | ||
1149 | mutex_unlock(&cgroup_mutex); | |
f2e85d57 | 1150 | |
2bd59d48 | 1151 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
1152 | cgroup_free_root(root); |
1153 | } | |
1154 | ||
ceb6a081 TH |
1155 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
1156 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 1157 | struct cgroup_root *root) |
7717f7ba | 1158 | { |
7717f7ba PM |
1159 | struct cgroup *res = NULL; |
1160 | ||
96d365e0 | 1161 | lockdep_assert_held(&cgroup_mutex); |
f0d9a5f1 | 1162 | lockdep_assert_held(&css_set_lock); |
96d365e0 | 1163 | |
5abb8855 | 1164 | if (cset == &init_css_set) { |
3dd06ffa | 1165 | res = &root->cgrp; |
7717f7ba | 1166 | } else { |
69d0206c TH |
1167 | struct cgrp_cset_link *link; |
1168 | ||
1169 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 1170 | struct cgroup *c = link->cgrp; |
69d0206c | 1171 | |
7717f7ba PM |
1172 | if (c->root == root) { |
1173 | res = c; | |
1174 | break; | |
1175 | } | |
1176 | } | |
1177 | } | |
96d365e0 | 1178 | |
7717f7ba PM |
1179 | BUG_ON(!res); |
1180 | return res; | |
1181 | } | |
1182 | ||
ddbcc7e8 | 1183 | /* |
ceb6a081 | 1184 | * Return the cgroup for "task" from the given hierarchy. Must be |
f0d9a5f1 | 1185 | * called with cgroup_mutex and css_set_lock held. |
ceb6a081 TH |
1186 | */ |
1187 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 1188 | struct cgroup_root *root) |
ceb6a081 TH |
1189 | { |
1190 | /* | |
1191 | * No need to lock the task - since we hold cgroup_mutex the | |
1192 | * task can't change groups, so the only thing that can happen | |
1193 | * is that it exits and its css is set back to init_css_set. | |
1194 | */ | |
1195 | return cset_cgroup_from_root(task_css_set(task), root); | |
1196 | } | |
1197 | ||
ddbcc7e8 | 1198 | /* |
ddbcc7e8 PM |
1199 | * A task must hold cgroup_mutex to modify cgroups. |
1200 | * | |
1201 | * Any task can increment and decrement the count field without lock. | |
1202 | * So in general, code holding cgroup_mutex can't rely on the count | |
1203 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 1204 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
1205 | * means that no tasks are currently attached, therefore there is no |
1206 | * way a task attached to that cgroup can fork (the other way to | |
1207 | * increment the count). So code holding cgroup_mutex can safely | |
1208 | * assume that if the count is zero, it will stay zero. Similarly, if | |
1209 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
1210 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
1211 | * needs that mutex. | |
1212 | * | |
ddbcc7e8 PM |
1213 | * A cgroup can only be deleted if both its 'count' of using tasks |
1214 | * is zero, and its list of 'children' cgroups is empty. Since all | |
1215 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 1216 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 1217 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 1218 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
1219 | * |
1220 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 1221 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
1222 | */ |
1223 | ||
2bd59d48 | 1224 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 1225 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 1226 | |
8d7e6fb0 TH |
1227 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
1228 | char *buf) | |
ddbcc7e8 | 1229 | { |
3e1d2eed TH |
1230 | struct cgroup_subsys *ss = cft->ss; |
1231 | ||
8d7e6fb0 TH |
1232 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
1233 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
1234 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
3e1d2eed TH |
1235 | cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
1236 | cft->name); | |
8d7e6fb0 TH |
1237 | else |
1238 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
1239 | return buf; | |
ddbcc7e8 PM |
1240 | } |
1241 | ||
f2e85d57 TH |
1242 | /** |
1243 | * cgroup_file_mode - deduce file mode of a control file | |
1244 | * @cft: the control file in question | |
1245 | * | |
7dbdb199 | 1246 | * S_IRUGO for read, S_IWUSR for write. |
f2e85d57 TH |
1247 | */ |
1248 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 1249 | { |
f2e85d57 | 1250 | umode_t mode = 0; |
65dff759 | 1251 | |
f2e85d57 TH |
1252 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
1253 | mode |= S_IRUGO; | |
1254 | ||
7dbdb199 TH |
1255 | if (cft->write_u64 || cft->write_s64 || cft->write) { |
1256 | if (cft->flags & CFTYPE_WORLD_WRITABLE) | |
1257 | mode |= S_IWUGO; | |
1258 | else | |
1259 | mode |= S_IWUSR; | |
1260 | } | |
f2e85d57 TH |
1261 | |
1262 | return mode; | |
65dff759 LZ |
1263 | } |
1264 | ||
af0ba678 | 1265 | /** |
0f060deb | 1266 | * cgroup_calc_child_subsys_mask - calculate child_subsys_mask |
af0ba678 | 1267 | * @cgrp: the target cgroup |
0f060deb | 1268 | * @subtree_control: the new subtree_control mask to consider |
af0ba678 TH |
1269 | * |
1270 | * On the default hierarchy, a subsystem may request other subsystems to be | |
1271 | * enabled together through its ->depends_on mask. In such cases, more | |
1272 | * subsystems than specified in "cgroup.subtree_control" may be enabled. | |
1273 | * | |
0f060deb TH |
1274 | * This function calculates which subsystems need to be enabled if |
1275 | * @subtree_control is to be applied to @cgrp. The returned mask is always | |
1276 | * a superset of @subtree_control and follows the usual hierarchy rules. | |
af0ba678 | 1277 | */ |
8ab456ac AS |
1278 | static unsigned long cgroup_calc_child_subsys_mask(struct cgroup *cgrp, |
1279 | unsigned long subtree_control) | |
667c2491 | 1280 | { |
af0ba678 | 1281 | struct cgroup *parent = cgroup_parent(cgrp); |
8ab456ac | 1282 | unsigned long cur_ss_mask = subtree_control; |
af0ba678 TH |
1283 | struct cgroup_subsys *ss; |
1284 | int ssid; | |
1285 | ||
1286 | lockdep_assert_held(&cgroup_mutex); | |
1287 | ||
0f060deb TH |
1288 | if (!cgroup_on_dfl(cgrp)) |
1289 | return cur_ss_mask; | |
af0ba678 TH |
1290 | |
1291 | while (true) { | |
8ab456ac | 1292 | unsigned long new_ss_mask = cur_ss_mask; |
af0ba678 | 1293 | |
a966a4ed AS |
1294 | for_each_subsys_which(ss, ssid, &cur_ss_mask) |
1295 | new_ss_mask |= ss->depends_on; | |
af0ba678 TH |
1296 | |
1297 | /* | |
1298 | * Mask out subsystems which aren't available. This can | |
1299 | * happen only if some depended-upon subsystems were bound | |
1300 | * to non-default hierarchies. | |
1301 | */ | |
1302 | if (parent) | |
1303 | new_ss_mask &= parent->child_subsys_mask; | |
1304 | else | |
1305 | new_ss_mask &= cgrp->root->subsys_mask; | |
1306 | ||
1307 | if (new_ss_mask == cur_ss_mask) | |
1308 | break; | |
1309 | cur_ss_mask = new_ss_mask; | |
1310 | } | |
1311 | ||
0f060deb TH |
1312 | return cur_ss_mask; |
1313 | } | |
1314 | ||
1315 | /** | |
1316 | * cgroup_refresh_child_subsys_mask - update child_subsys_mask | |
1317 | * @cgrp: the target cgroup | |
1318 | * | |
1319 | * Update @cgrp->child_subsys_mask according to the current | |
1320 | * @cgrp->subtree_control using cgroup_calc_child_subsys_mask(). | |
1321 | */ | |
1322 | static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp) | |
1323 | { | |
1324 | cgrp->child_subsys_mask = | |
1325 | cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control); | |
667c2491 TH |
1326 | } |
1327 | ||
a9746d8d TH |
1328 | /** |
1329 | * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods | |
1330 | * @kn: the kernfs_node being serviced | |
1331 | * | |
1332 | * This helper undoes cgroup_kn_lock_live() and should be invoked before | |
1333 | * the method finishes if locking succeeded. Note that once this function | |
1334 | * returns the cgroup returned by cgroup_kn_lock_live() may become | |
1335 | * inaccessible any time. If the caller intends to continue to access the | |
1336 | * cgroup, it should pin it before invoking this function. | |
1337 | */ | |
1338 | static void cgroup_kn_unlock(struct kernfs_node *kn) | |
ddbcc7e8 | 1339 | { |
a9746d8d TH |
1340 | struct cgroup *cgrp; |
1341 | ||
1342 | if (kernfs_type(kn) == KERNFS_DIR) | |
1343 | cgrp = kn->priv; | |
1344 | else | |
1345 | cgrp = kn->parent->priv; | |
1346 | ||
1347 | mutex_unlock(&cgroup_mutex); | |
a9746d8d TH |
1348 | |
1349 | kernfs_unbreak_active_protection(kn); | |
1350 | cgroup_put(cgrp); | |
ddbcc7e8 PM |
1351 | } |
1352 | ||
a9746d8d TH |
1353 | /** |
1354 | * cgroup_kn_lock_live - locking helper for cgroup kernfs methods | |
1355 | * @kn: the kernfs_node being serviced | |
1356 | * | |
1357 | * This helper is to be used by a cgroup kernfs method currently servicing | |
1358 | * @kn. It breaks the active protection, performs cgroup locking and | |
1359 | * verifies that the associated cgroup is alive. Returns the cgroup if | |
1360 | * alive; otherwise, %NULL. A successful return should be undone by a | |
1361 | * matching cgroup_kn_unlock() invocation. | |
1362 | * | |
1363 | * Any cgroup kernfs method implementation which requires locking the | |
1364 | * associated cgroup should use this helper. It avoids nesting cgroup | |
1365 | * locking under kernfs active protection and allows all kernfs operations | |
1366 | * including self-removal. | |
1367 | */ | |
1368 | static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn) | |
05ef1d7c | 1369 | { |
a9746d8d TH |
1370 | struct cgroup *cgrp; |
1371 | ||
1372 | if (kernfs_type(kn) == KERNFS_DIR) | |
1373 | cgrp = kn->priv; | |
1374 | else | |
1375 | cgrp = kn->parent->priv; | |
05ef1d7c | 1376 | |
2739d3cc | 1377 | /* |
01f6474c | 1378 | * We're gonna grab cgroup_mutex which nests outside kernfs |
a9746d8d TH |
1379 | * active_ref. cgroup liveliness check alone provides enough |
1380 | * protection against removal. Ensure @cgrp stays accessible and | |
1381 | * break the active_ref protection. | |
2739d3cc | 1382 | */ |
aa32362f LZ |
1383 | if (!cgroup_tryget(cgrp)) |
1384 | return NULL; | |
a9746d8d TH |
1385 | kernfs_break_active_protection(kn); |
1386 | ||
2bd59d48 | 1387 | mutex_lock(&cgroup_mutex); |
05ef1d7c | 1388 | |
a9746d8d TH |
1389 | if (!cgroup_is_dead(cgrp)) |
1390 | return cgrp; | |
1391 | ||
1392 | cgroup_kn_unlock(kn); | |
1393 | return NULL; | |
ddbcc7e8 | 1394 | } |
05ef1d7c | 1395 | |
2739d3cc | 1396 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 1397 | { |
2bd59d48 | 1398 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 1399 | |
01f6474c | 1400 | lockdep_assert_held(&cgroup_mutex); |
2bd59d48 | 1401 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
1402 | } |
1403 | ||
13af07df | 1404 | /** |
4df8dc90 TH |
1405 | * css_clear_dir - remove subsys files in a cgroup directory |
1406 | * @css: taget css | |
1407 | * @cgrp_override: specify if target cgroup is different from css->cgroup | |
13af07df | 1408 | */ |
4df8dc90 TH |
1409 | static void css_clear_dir(struct cgroup_subsys_state *css, |
1410 | struct cgroup *cgrp_override) | |
05ef1d7c | 1411 | { |
4df8dc90 TH |
1412 | struct cgroup *cgrp = cgrp_override ?: css->cgroup; |
1413 | struct cftype *cfts; | |
05ef1d7c | 1414 | |
4df8dc90 TH |
1415 | list_for_each_entry(cfts, &css->ss->cfts, node) |
1416 | cgroup_addrm_files(css, cgrp, cfts, false); | |
ddbcc7e8 PM |
1417 | } |
1418 | ||
ccdca218 | 1419 | /** |
4df8dc90 TH |
1420 | * css_populate_dir - create subsys files in a cgroup directory |
1421 | * @css: target css | |
1422 | * @cgrp_overried: specify if target cgroup is different from css->cgroup | |
ccdca218 TH |
1423 | * |
1424 | * On failure, no file is added. | |
1425 | */ | |
4df8dc90 TH |
1426 | static int css_populate_dir(struct cgroup_subsys_state *css, |
1427 | struct cgroup *cgrp_override) | |
ccdca218 | 1428 | { |
4df8dc90 TH |
1429 | struct cgroup *cgrp = cgrp_override ?: css->cgroup; |
1430 | struct cftype *cfts, *failed_cfts; | |
1431 | int ret; | |
ccdca218 | 1432 | |
4df8dc90 TH |
1433 | if (!css->ss) { |
1434 | if (cgroup_on_dfl(cgrp)) | |
1435 | cfts = cgroup_dfl_base_files; | |
1436 | else | |
1437 | cfts = cgroup_legacy_base_files; | |
ccdca218 | 1438 | |
4df8dc90 TH |
1439 | return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
1440 | } | |
ccdca218 | 1441 | |
4df8dc90 TH |
1442 | list_for_each_entry(cfts, &css->ss->cfts, node) { |
1443 | ret = cgroup_addrm_files(css, cgrp, cfts, true); | |
1444 | if (ret < 0) { | |
1445 | failed_cfts = cfts; | |
1446 | goto err; | |
ccdca218 TH |
1447 | } |
1448 | } | |
1449 | return 0; | |
1450 | err: | |
4df8dc90 TH |
1451 | list_for_each_entry(cfts, &css->ss->cfts, node) { |
1452 | if (cfts == failed_cfts) | |
1453 | break; | |
1454 | cgroup_addrm_files(css, cgrp, cfts, false); | |
1455 | } | |
ccdca218 TH |
1456 | return ret; |
1457 | } | |
1458 | ||
8ab456ac AS |
1459 | static int rebind_subsystems(struct cgroup_root *dst_root, |
1460 | unsigned long ss_mask) | |
ddbcc7e8 | 1461 | { |
1ada4838 | 1462 | struct cgroup *dcgrp = &dst_root->cgrp; |
30159ec7 | 1463 | struct cgroup_subsys *ss; |
8ab456ac | 1464 | unsigned long tmp_ss_mask; |
2d8f243a | 1465 | int ssid, i, ret; |
ddbcc7e8 | 1466 | |
ace2bee8 | 1467 | lockdep_assert_held(&cgroup_mutex); |
ddbcc7e8 | 1468 | |
a966a4ed | 1469 | for_each_subsys_which(ss, ssid, &ss_mask) { |
7fd8c565 TH |
1470 | /* if @ss has non-root csses attached to it, can't move */ |
1471 | if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) | |
3ed80a62 | 1472 | return -EBUSY; |
1d5be6b2 | 1473 | |
5df36032 | 1474 | /* can't move between two non-dummy roots either */ |
7fd8c565 | 1475 | if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
5df36032 | 1476 | return -EBUSY; |
ddbcc7e8 PM |
1477 | } |
1478 | ||
5533e011 TH |
1479 | /* skip creating root files on dfl_root for inhibited subsystems */ |
1480 | tmp_ss_mask = ss_mask; | |
1481 | if (dst_root == &cgrp_dfl_root) | |
1482 | tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask; | |
1483 | ||
4df8dc90 TH |
1484 | for_each_subsys_which(ss, ssid, &tmp_ss_mask) { |
1485 | struct cgroup *scgrp = &ss->root->cgrp; | |
1486 | int tssid; | |
1487 | ||
1488 | ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp); | |
1489 | if (!ret) | |
1490 | continue; | |
ddbcc7e8 | 1491 | |
a2dd4247 TH |
1492 | /* |
1493 | * Rebinding back to the default root is not allowed to | |
1494 | * fail. Using both default and non-default roots should | |
1495 | * be rare. Moving subsystems back and forth even more so. | |
1496 | * Just warn about it and continue. | |
1497 | */ | |
4df8dc90 TH |
1498 | if (dst_root == &cgrp_dfl_root) { |
1499 | if (cgrp_dfl_root_visible) { | |
1500 | pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n", | |
1501 | ret, ss_mask); | |
1502 | pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); | |
1503 | } | |
1504 | continue; | |
a2dd4247 | 1505 | } |
4df8dc90 TH |
1506 | |
1507 | for_each_subsys_which(ss, tssid, &tmp_ss_mask) { | |
1508 | if (tssid == ssid) | |
1509 | break; | |
1510 | css_clear_dir(cgroup_css(scgrp, ss), dcgrp); | |
1511 | } | |
1512 | return ret; | |
5df36032 | 1513 | } |
3126121f TH |
1514 | |
1515 | /* | |
1516 | * Nothing can fail from this point on. Remove files for the | |
1517 | * removed subsystems and rebind each subsystem. | |
1518 | */ | |
a966a4ed | 1519 | for_each_subsys_which(ss, ssid, &ss_mask) { |
1ada4838 TH |
1520 | struct cgroup_root *src_root = ss->root; |
1521 | struct cgroup *scgrp = &src_root->cgrp; | |
1522 | struct cgroup_subsys_state *css = cgroup_css(scgrp, ss); | |
2d8f243a | 1523 | struct css_set *cset; |
a8a648c4 | 1524 | |
1ada4838 | 1525 | WARN_ON(!css || cgroup_css(dcgrp, ss)); |
a8a648c4 | 1526 | |
4df8dc90 TH |
1527 | css_clear_dir(css, NULL); |
1528 | ||
1ada4838 TH |
1529 | RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); |
1530 | rcu_assign_pointer(dcgrp->subsys[ssid], css); | |
5df36032 | 1531 | ss->root = dst_root; |
1ada4838 | 1532 | css->cgroup = dcgrp; |
73e80ed8 | 1533 | |
f0d9a5f1 | 1534 | spin_lock_bh(&css_set_lock); |
2d8f243a TH |
1535 | hash_for_each(css_set_table, i, cset, hlist) |
1536 | list_move_tail(&cset->e_cset_node[ss->id], | |
1ada4838 | 1537 | &dcgrp->e_csets[ss->id]); |
f0d9a5f1 | 1538 | spin_unlock_bh(&css_set_lock); |
2d8f243a | 1539 | |
f392e51c | 1540 | src_root->subsys_mask &= ~(1 << ssid); |
1ada4838 TH |
1541 | scgrp->subtree_control &= ~(1 << ssid); |
1542 | cgroup_refresh_child_subsys_mask(scgrp); | |
f392e51c | 1543 | |
bd53d617 | 1544 | /* default hierarchy doesn't enable controllers by default */ |
f392e51c | 1545 | dst_root->subsys_mask |= 1 << ssid; |
49d1dc4b TH |
1546 | if (dst_root == &cgrp_dfl_root) { |
1547 | static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); | |
1548 | } else { | |
1ada4838 TH |
1549 | dcgrp->subtree_control |= 1 << ssid; |
1550 | cgroup_refresh_child_subsys_mask(dcgrp); | |
49d1dc4b | 1551 | static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
667c2491 | 1552 | } |
a8a648c4 | 1553 | |
5df36032 TH |
1554 | if (ss->bind) |
1555 | ss->bind(css); | |
ddbcc7e8 | 1556 | } |
ddbcc7e8 | 1557 | |
1ada4838 | 1558 | kernfs_activate(dcgrp->kn); |
ddbcc7e8 PM |
1559 | return 0; |
1560 | } | |
1561 | ||
2bd59d48 TH |
1562 | static int cgroup_show_options(struct seq_file *seq, |
1563 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1564 | { |
3dd06ffa | 1565 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1566 | struct cgroup_subsys *ss; |
b85d2040 | 1567 | int ssid; |
ddbcc7e8 | 1568 | |
d98817d4 TH |
1569 | if (root != &cgrp_dfl_root) |
1570 | for_each_subsys(ss, ssid) | |
1571 | if (root->subsys_mask & (1 << ssid)) | |
61e57c0c | 1572 | seq_show_option(seq, ss->legacy_name, NULL); |
93438629 | 1573 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1574 | seq_puts(seq, ",noprefix"); |
93438629 | 1575 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1576 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1577 | |
1578 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1579 | if (strlen(root->release_agent_path)) |
a068acf2 KC |
1580 | seq_show_option(seq, "release_agent", |
1581 | root->release_agent_path); | |
69e943b7 TH |
1582 | spin_unlock(&release_agent_path_lock); |
1583 | ||
3dd06ffa | 1584 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1585 | seq_puts(seq, ",clone_children"); |
c6d57f33 | 1586 | if (strlen(root->name)) |
a068acf2 | 1587 | seq_show_option(seq, "name", root->name); |
ddbcc7e8 PM |
1588 | return 0; |
1589 | } | |
1590 | ||
1591 | struct cgroup_sb_opts { | |
8ab456ac | 1592 | unsigned long subsys_mask; |
69dfa00c | 1593 | unsigned int flags; |
81a6a5cd | 1594 | char *release_agent; |
2260e7fc | 1595 | bool cpuset_clone_children; |
c6d57f33 | 1596 | char *name; |
2c6ab6d2 PM |
1597 | /* User explicitly requested empty subsystem */ |
1598 | bool none; | |
ddbcc7e8 PM |
1599 | }; |
1600 | ||
cf5d5941 | 1601 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1602 | { |
32a8cf23 DL |
1603 | char *token, *o = data; |
1604 | bool all_ss = false, one_ss = false; | |
8ab456ac | 1605 | unsigned long mask = -1UL; |
30159ec7 | 1606 | struct cgroup_subsys *ss; |
7b9a6ba5 | 1607 | int nr_opts = 0; |
30159ec7 | 1608 | int i; |
f9ab5b5b LZ |
1609 | |
1610 | #ifdef CONFIG_CPUSETS | |
69dfa00c | 1611 | mask = ~(1U << cpuset_cgrp_id); |
f9ab5b5b | 1612 | #endif |
ddbcc7e8 | 1613 | |
c6d57f33 | 1614 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1615 | |
1616 | while ((token = strsep(&o, ",")) != NULL) { | |
7b9a6ba5 TH |
1617 | nr_opts++; |
1618 | ||
ddbcc7e8 PM |
1619 | if (!*token) |
1620 | return -EINVAL; | |
32a8cf23 | 1621 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1622 | /* Explicitly have no subsystems */ |
1623 | opts->none = true; | |
32a8cf23 DL |
1624 | continue; |
1625 | } | |
1626 | if (!strcmp(token, "all")) { | |
1627 | /* Mutually exclusive option 'all' + subsystem name */ | |
1628 | if (one_ss) | |
1629 | return -EINVAL; | |
1630 | all_ss = true; | |
1631 | continue; | |
1632 | } | |
873fe09e TH |
1633 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1634 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1635 | continue; | |
1636 | } | |
32a8cf23 | 1637 | if (!strcmp(token, "noprefix")) { |
93438629 | 1638 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1639 | continue; |
1640 | } | |
1641 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1642 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1643 | continue; |
1644 | } | |
03b1cde6 | 1645 | if (!strcmp(token, "xattr")) { |
93438629 | 1646 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1647 | continue; |
1648 | } | |
32a8cf23 | 1649 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1650 | /* Specifying two release agents is forbidden */ |
1651 | if (opts->release_agent) | |
1652 | return -EINVAL; | |
c6d57f33 | 1653 | opts->release_agent = |
e400c285 | 1654 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1655 | if (!opts->release_agent) |
1656 | return -ENOMEM; | |
32a8cf23 DL |
1657 | continue; |
1658 | } | |
1659 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1660 | const char *name = token + 5; |
1661 | /* Can't specify an empty name */ | |
1662 | if (!strlen(name)) | |
1663 | return -EINVAL; | |
1664 | /* Must match [\w.-]+ */ | |
1665 | for (i = 0; i < strlen(name); i++) { | |
1666 | char c = name[i]; | |
1667 | if (isalnum(c)) | |
1668 | continue; | |
1669 | if ((c == '.') || (c == '-') || (c == '_')) | |
1670 | continue; | |
1671 | return -EINVAL; | |
1672 | } | |
1673 | /* Specifying two names is forbidden */ | |
1674 | if (opts->name) | |
1675 | return -EINVAL; | |
1676 | opts->name = kstrndup(name, | |
e400c285 | 1677 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1678 | GFP_KERNEL); |
1679 | if (!opts->name) | |
1680 | return -ENOMEM; | |
32a8cf23 DL |
1681 | |
1682 | continue; | |
1683 | } | |
1684 | ||
30159ec7 | 1685 | for_each_subsys(ss, i) { |
3e1d2eed | 1686 | if (strcmp(token, ss->legacy_name)) |
32a8cf23 | 1687 | continue; |
fc5ed1e9 | 1688 | if (!cgroup_ssid_enabled(i)) |
32a8cf23 DL |
1689 | continue; |
1690 | ||
1691 | /* Mutually exclusive option 'all' + subsystem name */ | |
1692 | if (all_ss) | |
1693 | return -EINVAL; | |
69dfa00c | 1694 | opts->subsys_mask |= (1 << i); |
32a8cf23 DL |
1695 | one_ss = true; |
1696 | ||
1697 | break; | |
1698 | } | |
1699 | if (i == CGROUP_SUBSYS_COUNT) | |
1700 | return -ENOENT; | |
1701 | } | |
1702 | ||
873fe09e | 1703 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
ed3d261b | 1704 | pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); |
7b9a6ba5 TH |
1705 | if (nr_opts != 1) { |
1706 | pr_err("sane_behavior: no other mount options allowed\n"); | |
873fe09e TH |
1707 | return -EINVAL; |
1708 | } | |
7b9a6ba5 | 1709 | return 0; |
873fe09e TH |
1710 | } |
1711 | ||
7b9a6ba5 TH |
1712 | /* |
1713 | * If the 'all' option was specified select all the subsystems, | |
1714 | * otherwise if 'none', 'name=' and a subsystem name options were | |
1715 | * not specified, let's default to 'all' | |
1716 | */ | |
1717 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1718 | for_each_subsys(ss, i) | |
fc5ed1e9 | 1719 | if (cgroup_ssid_enabled(i)) |
7b9a6ba5 TH |
1720 | opts->subsys_mask |= (1 << i); |
1721 | ||
1722 | /* | |
1723 | * We either have to specify by name or by subsystems. (So all | |
1724 | * empty hierarchies must have a name). | |
1725 | */ | |
1726 | if (!opts->subsys_mask && !opts->name) | |
1727 | return -EINVAL; | |
1728 | ||
f9ab5b5b LZ |
1729 | /* |
1730 | * Option noprefix was introduced just for backward compatibility | |
1731 | * with the old cpuset, so we allow noprefix only if mounting just | |
1732 | * the cpuset subsystem. | |
1733 | */ | |
93438629 | 1734 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1735 | return -EINVAL; |
1736 | ||
2c6ab6d2 | 1737 | /* Can't specify "none" and some subsystems */ |
a1a71b45 | 1738 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1739 | return -EINVAL; |
1740 | ||
ddbcc7e8 PM |
1741 | return 0; |
1742 | } | |
1743 | ||
2bd59d48 | 1744 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1745 | { |
1746 | int ret = 0; | |
3dd06ffa | 1747 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1748 | struct cgroup_sb_opts opts; |
8ab456ac | 1749 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1750 | |
aa6ec29b TH |
1751 | if (root == &cgrp_dfl_root) { |
1752 | pr_err("remount is not allowed\n"); | |
873fe09e TH |
1753 | return -EINVAL; |
1754 | } | |
1755 | ||
ddbcc7e8 PM |
1756 | mutex_lock(&cgroup_mutex); |
1757 | ||
1758 | /* See what subsystems are wanted */ | |
1759 | ret = parse_cgroupfs_options(data, &opts); | |
1760 | if (ret) | |
1761 | goto out_unlock; | |
1762 | ||
f392e51c | 1763 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
ed3d261b | 1764 | pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
a2a1f9ea | 1765 | task_tgid_nr(current), current->comm); |
8b5a5a9d | 1766 | |
f392e51c TH |
1767 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1768 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1769 | |
cf5d5941 | 1770 | /* Don't allow flags or name to change at remount */ |
7450e90b | 1771 | if ((opts.flags ^ root->flags) || |
cf5d5941 | 1772 | (opts.name && strcmp(opts.name, root->name))) { |
69dfa00c | 1773 | pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
7450e90b | 1774 | opts.flags, opts.name ?: "", root->flags, root->name); |
c6d57f33 PM |
1775 | ret = -EINVAL; |
1776 | goto out_unlock; | |
1777 | } | |
1778 | ||
f172e67c | 1779 | /* remounting is not allowed for populated hierarchies */ |
d5c419b6 | 1780 | if (!list_empty(&root->cgrp.self.children)) { |
f172e67c | 1781 | ret = -EBUSY; |
0670e08b | 1782 | goto out_unlock; |
cf5d5941 | 1783 | } |
ddbcc7e8 | 1784 | |
5df36032 | 1785 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1786 | if (ret) |
0670e08b | 1787 | goto out_unlock; |
ddbcc7e8 | 1788 | |
3dd06ffa | 1789 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1790 | |
69e943b7 TH |
1791 | if (opts.release_agent) { |
1792 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1793 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1794 | spin_unlock(&release_agent_path_lock); |
1795 | } | |
ddbcc7e8 | 1796 | out_unlock: |
66bdc9cf | 1797 | kfree(opts.release_agent); |
c6d57f33 | 1798 | kfree(opts.name); |
ddbcc7e8 | 1799 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
1800 | return ret; |
1801 | } | |
1802 | ||
afeb0f9f TH |
1803 | /* |
1804 | * To reduce the fork() overhead for systems that are not actually using | |
1805 | * their cgroups capability, we don't maintain the lists running through | |
1806 | * each css_set to its tasks until we see the list actually used - in other | |
1807 | * words after the first mount. | |
1808 | */ | |
1809 | static bool use_task_css_set_links __read_mostly; | |
1810 | ||
1811 | static void cgroup_enable_task_cg_lists(void) | |
1812 | { | |
1813 | struct task_struct *p, *g; | |
1814 | ||
f0d9a5f1 | 1815 | spin_lock_bh(&css_set_lock); |
afeb0f9f TH |
1816 | |
1817 | if (use_task_css_set_links) | |
1818 | goto out_unlock; | |
1819 | ||
1820 | use_task_css_set_links = true; | |
1821 | ||
1822 | /* | |
1823 | * We need tasklist_lock because RCU is not safe against | |
1824 | * while_each_thread(). Besides, a forking task that has passed | |
1825 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1826 | * is not guaranteed to have its child immediately visible in the | |
1827 | * tasklist if we walk through it with RCU. | |
1828 | */ | |
1829 | read_lock(&tasklist_lock); | |
1830 | do_each_thread(g, p) { | |
afeb0f9f TH |
1831 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1832 | task_css_set(p) != &init_css_set); | |
1833 | ||
1834 | /* | |
1835 | * We should check if the process is exiting, otherwise | |
1836 | * it will race with cgroup_exit() in that the list | |
1837 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1838 | * Do it while holding siglock so that we don't end up |
1839 | * racing against cgroup_exit(). | |
afeb0f9f | 1840 | */ |
f153ad11 | 1841 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1842 | if (!(p->flags & PF_EXITING)) { |
1843 | struct css_set *cset = task_css_set(p); | |
1844 | ||
0de0942d TH |
1845 | if (!css_set_populated(cset)) |
1846 | css_set_update_populated(cset, true); | |
389b9c1b | 1847 | list_add_tail(&p->cg_list, &cset->tasks); |
eaf797ab TH |
1848 | get_css_set(cset); |
1849 | } | |
f153ad11 | 1850 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1851 | } while_each_thread(g, p); |
1852 | read_unlock(&tasklist_lock); | |
1853 | out_unlock: | |
f0d9a5f1 | 1854 | spin_unlock_bh(&css_set_lock); |
afeb0f9f | 1855 | } |
ddbcc7e8 | 1856 | |
cc31edce PM |
1857 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1858 | { | |
2d8f243a TH |
1859 | struct cgroup_subsys *ss; |
1860 | int ssid; | |
1861 | ||
d5c419b6 TH |
1862 | INIT_LIST_HEAD(&cgrp->self.sibling); |
1863 | INIT_LIST_HEAD(&cgrp->self.children); | |
6f60eade | 1864 | INIT_LIST_HEAD(&cgrp->self.files); |
69d0206c | 1865 | INIT_LIST_HEAD(&cgrp->cset_links); |
72a8cb30 BB |
1866 | INIT_LIST_HEAD(&cgrp->pidlists); |
1867 | mutex_init(&cgrp->pidlist_mutex); | |
9d800df1 | 1868 | cgrp->self.cgroup = cgrp; |
184faf32 | 1869 | cgrp->self.flags |= CSS_ONLINE; |
2d8f243a TH |
1870 | |
1871 | for_each_subsys(ss, ssid) | |
1872 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]); | |
f8f22e53 TH |
1873 | |
1874 | init_waitqueue_head(&cgrp->offline_waitq); | |
971ff493 | 1875 | INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
cc31edce | 1876 | } |
c6d57f33 | 1877 | |
3dd06ffa | 1878 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1879 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1880 | { |
3dd06ffa | 1881 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1882 | |
ddbcc7e8 | 1883 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1884 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1885 | cgrp->root = root; |
cc31edce | 1886 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1887 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1888 | |
c6d57f33 PM |
1889 | root->flags = opts->flags; |
1890 | if (opts->release_agent) | |
1891 | strcpy(root->release_agent_path, opts->release_agent); | |
1892 | if (opts->name) | |
1893 | strcpy(root->name, opts->name); | |
2260e7fc | 1894 | if (opts->cpuset_clone_children) |
3dd06ffa | 1895 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1896 | } |
1897 | ||
8ab456ac | 1898 | static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) |
2c6ab6d2 | 1899 | { |
d427dfeb | 1900 | LIST_HEAD(tmp_links); |
3dd06ffa | 1901 | struct cgroup *root_cgrp = &root->cgrp; |
d427dfeb | 1902 | struct css_set *cset; |
d427dfeb | 1903 | int i, ret; |
2c6ab6d2 | 1904 | |
d427dfeb | 1905 | lockdep_assert_held(&cgroup_mutex); |
c6d57f33 | 1906 | |
cf780b7d | 1907 | ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
d427dfeb | 1908 | if (ret < 0) |
2bd59d48 | 1909 | goto out; |
d427dfeb | 1910 | root_cgrp->id = ret; |
c6d57f33 | 1911 | |
2aad2a86 TH |
1912 | ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, |
1913 | GFP_KERNEL); | |
9d755d33 TH |
1914 | if (ret) |
1915 | goto out; | |
1916 | ||
d427dfeb | 1917 | /* |
f0d9a5f1 | 1918 | * We're accessing css_set_count without locking css_set_lock here, |
d427dfeb TH |
1919 | * but that's OK - it can only be increased by someone holding |
1920 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1921 | * have some link structures left over | |
1922 | */ | |
1923 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1924 | if (ret) | |
9d755d33 | 1925 | goto cancel_ref; |
ddbcc7e8 | 1926 | |
985ed670 | 1927 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1928 | if (ret) |
9d755d33 | 1929 | goto cancel_ref; |
ddbcc7e8 | 1930 | |
2bd59d48 TH |
1931 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1932 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1933 | root_cgrp); | |
1934 | if (IS_ERR(root->kf_root)) { | |
1935 | ret = PTR_ERR(root->kf_root); | |
1936 | goto exit_root_id; | |
1937 | } | |
1938 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1939 | |
4df8dc90 | 1940 | ret = css_populate_dir(&root_cgrp->self, NULL); |
d427dfeb | 1941 | if (ret) |
2bd59d48 | 1942 | goto destroy_root; |
ddbcc7e8 | 1943 | |
5df36032 | 1944 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1945 | if (ret) |
2bd59d48 | 1946 | goto destroy_root; |
ddbcc7e8 | 1947 | |
d427dfeb TH |
1948 | /* |
1949 | * There must be no failure case after here, since rebinding takes | |
1950 | * care of subsystems' refcounts, which are explicitly dropped in | |
1951 | * the failure exit path. | |
1952 | */ | |
1953 | list_add(&root->root_list, &cgroup_roots); | |
1954 | cgroup_root_count++; | |
0df6a63f | 1955 | |
d427dfeb | 1956 | /* |
3dd06ffa | 1957 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1958 | * objects. |
1959 | */ | |
f0d9a5f1 | 1960 | spin_lock_bh(&css_set_lock); |
0de0942d | 1961 | hash_for_each(css_set_table, i, cset, hlist) { |
d427dfeb | 1962 | link_css_set(&tmp_links, cset, root_cgrp); |
0de0942d TH |
1963 | if (css_set_populated(cset)) |
1964 | cgroup_update_populated(root_cgrp, true); | |
1965 | } | |
f0d9a5f1 | 1966 | spin_unlock_bh(&css_set_lock); |
ddbcc7e8 | 1967 | |
d5c419b6 | 1968 | BUG_ON(!list_empty(&root_cgrp->self.children)); |
3c9c825b | 1969 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1970 | |
2bd59d48 | 1971 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1972 | ret = 0; |
2bd59d48 | 1973 | goto out; |
d427dfeb | 1974 | |
2bd59d48 TH |
1975 | destroy_root: |
1976 | kernfs_destroy_root(root->kf_root); | |
1977 | root->kf_root = NULL; | |
1978 | exit_root_id: | |
d427dfeb | 1979 | cgroup_exit_root_id(root); |
9d755d33 | 1980 | cancel_ref: |
9a1049da | 1981 | percpu_ref_exit(&root_cgrp->self.refcnt); |
2bd59d48 | 1982 | out: |
d427dfeb TH |
1983 | free_cgrp_cset_links(&tmp_links); |
1984 | return ret; | |
ddbcc7e8 PM |
1985 | } |
1986 | ||
f7e83571 | 1987 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1988 | int flags, const char *unused_dev_name, |
f7e83571 | 1989 | void *data) |
ddbcc7e8 | 1990 | { |
3a32bd72 | 1991 | struct super_block *pinned_sb = NULL; |
970317aa | 1992 | struct cgroup_subsys *ss; |
3dd06ffa | 1993 | struct cgroup_root *root; |
ddbcc7e8 | 1994 | struct cgroup_sb_opts opts; |
2bd59d48 | 1995 | struct dentry *dentry; |
8e30e2b8 | 1996 | int ret; |
970317aa | 1997 | int i; |
c6b3d5bc | 1998 | bool new_sb; |
ddbcc7e8 | 1999 | |
56fde9e0 TH |
2000 | /* |
2001 | * The first time anyone tries to mount a cgroup, enable the list | |
2002 | * linking each css_set to its tasks and fix up all existing tasks. | |
2003 | */ | |
2004 | if (!use_task_css_set_links) | |
2005 | cgroup_enable_task_cg_lists(); | |
e37a06f1 | 2006 | |
aae8aab4 | 2007 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
2008 | |
2009 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 2010 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 2011 | if (ret) |
8e30e2b8 | 2012 | goto out_unlock; |
a015edd2 | 2013 | |
2bd59d48 | 2014 | /* look for a matching existing root */ |
7b9a6ba5 | 2015 | if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) { |
a2dd4247 TH |
2016 | cgrp_dfl_root_visible = true; |
2017 | root = &cgrp_dfl_root; | |
2018 | cgroup_get(&root->cgrp); | |
2019 | ret = 0; | |
2020 | goto out_unlock; | |
ddbcc7e8 PM |
2021 | } |
2022 | ||
970317aa LZ |
2023 | /* |
2024 | * Destruction of cgroup root is asynchronous, so subsystems may | |
2025 | * still be dying after the previous unmount. Let's drain the | |
2026 | * dying subsystems. We just need to ensure that the ones | |
2027 | * unmounted previously finish dying and don't care about new ones | |
2028 | * starting. Testing ref liveliness is good enough. | |
2029 | */ | |
2030 | for_each_subsys(ss, i) { | |
2031 | if (!(opts.subsys_mask & (1 << i)) || | |
2032 | ss->root == &cgrp_dfl_root) | |
2033 | continue; | |
2034 | ||
2035 | if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { | |
2036 | mutex_unlock(&cgroup_mutex); | |
2037 | msleep(10); | |
2038 | ret = restart_syscall(); | |
2039 | goto out_free; | |
2040 | } | |
2041 | cgroup_put(&ss->root->cgrp); | |
2042 | } | |
2043 | ||
985ed670 | 2044 | for_each_root(root) { |
2bd59d48 | 2045 | bool name_match = false; |
3126121f | 2046 | |
3dd06ffa | 2047 | if (root == &cgrp_dfl_root) |
985ed670 | 2048 | continue; |
3126121f | 2049 | |
cf5d5941 | 2050 | /* |
2bd59d48 TH |
2051 | * If we asked for a name then it must match. Also, if |
2052 | * name matches but sybsys_mask doesn't, we should fail. | |
2053 | * Remember whether name matched. | |
cf5d5941 | 2054 | */ |
2bd59d48 TH |
2055 | if (opts.name) { |
2056 | if (strcmp(opts.name, root->name)) | |
2057 | continue; | |
2058 | name_match = true; | |
2059 | } | |
ddbcc7e8 | 2060 | |
c6d57f33 | 2061 | /* |
2bd59d48 TH |
2062 | * If we asked for subsystems (or explicitly for no |
2063 | * subsystems) then they must match. | |
c6d57f33 | 2064 | */ |
2bd59d48 | 2065 | if ((opts.subsys_mask || opts.none) && |
f392e51c | 2066 | (opts.subsys_mask != root->subsys_mask)) { |
2bd59d48 TH |
2067 | if (!name_match) |
2068 | continue; | |
2069 | ret = -EBUSY; | |
2070 | goto out_unlock; | |
2071 | } | |
873fe09e | 2072 | |
7b9a6ba5 TH |
2073 | if (root->flags ^ opts.flags) |
2074 | pr_warn("new mount options do not match the existing superblock, will be ignored\n"); | |
ddbcc7e8 | 2075 | |
776f02fa | 2076 | /* |
3a32bd72 LZ |
2077 | * We want to reuse @root whose lifetime is governed by its |
2078 | * ->cgrp. Let's check whether @root is alive and keep it | |
2079 | * that way. As cgroup_kill_sb() can happen anytime, we | |
2080 | * want to block it by pinning the sb so that @root doesn't | |
2081 | * get killed before mount is complete. | |
2082 | * | |
2083 | * With the sb pinned, tryget_live can reliably indicate | |
2084 | * whether @root can be reused. If it's being killed, | |
2085 | * drain it. We can use wait_queue for the wait but this | |
2086 | * path is super cold. Let's just sleep a bit and retry. | |
776f02fa | 2087 | */ |
3a32bd72 LZ |
2088 | pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
2089 | if (IS_ERR(pinned_sb) || | |
2090 | !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { | |
776f02fa | 2091 | mutex_unlock(&cgroup_mutex); |
3a32bd72 LZ |
2092 | if (!IS_ERR_OR_NULL(pinned_sb)) |
2093 | deactivate_super(pinned_sb); | |
776f02fa | 2094 | msleep(10); |
a015edd2 TH |
2095 | ret = restart_syscall(); |
2096 | goto out_free; | |
776f02fa | 2097 | } |
ddbcc7e8 | 2098 | |
776f02fa | 2099 | ret = 0; |
2bd59d48 | 2100 | goto out_unlock; |
ddbcc7e8 | 2101 | } |
ddbcc7e8 | 2102 | |
817929ec | 2103 | /* |
172a2c06 TH |
2104 | * No such thing, create a new one. name= matching without subsys |
2105 | * specification is allowed for already existing hierarchies but we | |
2106 | * can't create new one without subsys specification. | |
817929ec | 2107 | */ |
172a2c06 TH |
2108 | if (!opts.subsys_mask && !opts.none) { |
2109 | ret = -EINVAL; | |
2110 | goto out_unlock; | |
817929ec | 2111 | } |
817929ec | 2112 | |
172a2c06 TH |
2113 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
2114 | if (!root) { | |
2115 | ret = -ENOMEM; | |
2bd59d48 | 2116 | goto out_unlock; |
839ec545 | 2117 | } |
e5f6a860 | 2118 | |
172a2c06 TH |
2119 | init_cgroup_root(root, &opts); |
2120 | ||
35585573 | 2121 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
2122 | if (ret) |
2123 | cgroup_free_root(root); | |
fa3ca07e | 2124 | |
8e30e2b8 | 2125 | out_unlock: |
ddbcc7e8 | 2126 | mutex_unlock(&cgroup_mutex); |
a015edd2 | 2127 | out_free: |
c6d57f33 PM |
2128 | kfree(opts.release_agent); |
2129 | kfree(opts.name); | |
03b1cde6 | 2130 | |
2bd59d48 | 2131 | if (ret) |
8e30e2b8 | 2132 | return ERR_PTR(ret); |
2bd59d48 | 2133 | |
c9482a5b JZ |
2134 | dentry = kernfs_mount(fs_type, flags, root->kf_root, |
2135 | CGROUP_SUPER_MAGIC, &new_sb); | |
c6b3d5bc | 2136 | if (IS_ERR(dentry) || !new_sb) |
3dd06ffa | 2137 | cgroup_put(&root->cgrp); |
3a32bd72 LZ |
2138 | |
2139 | /* | |
2140 | * If @pinned_sb, we're reusing an existing root and holding an | |
2141 | * extra ref on its sb. Mount is complete. Put the extra ref. | |
2142 | */ | |
2143 | if (pinned_sb) { | |
2144 | WARN_ON(new_sb); | |
2145 | deactivate_super(pinned_sb); | |
2146 | } | |
2147 | ||
2bd59d48 TH |
2148 | return dentry; |
2149 | } | |
2150 | ||
2151 | static void cgroup_kill_sb(struct super_block *sb) | |
2152 | { | |
2153 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 2154 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 2155 | |
9d755d33 TH |
2156 | /* |
2157 | * If @root doesn't have any mounts or children, start killing it. | |
2158 | * This prevents new mounts by disabling percpu_ref_tryget_live(). | |
2159 | * cgroup_mount() may wait for @root's release. | |
1f779fb2 LZ |
2160 | * |
2161 | * And don't kill the default root. | |
9d755d33 | 2162 | */ |
3c606d35 | 2163 | if (!list_empty(&root->cgrp.self.children) || |
1f779fb2 | 2164 | root == &cgrp_dfl_root) |
9d755d33 TH |
2165 | cgroup_put(&root->cgrp); |
2166 | else | |
2167 | percpu_ref_kill(&root->cgrp.self.refcnt); | |
2168 | ||
2bd59d48 | 2169 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
2170 | } |
2171 | ||
2172 | static struct file_system_type cgroup_fs_type = { | |
2173 | .name = "cgroup", | |
f7e83571 | 2174 | .mount = cgroup_mount, |
ddbcc7e8 PM |
2175 | .kill_sb = cgroup_kill_sb, |
2176 | }; | |
2177 | ||
857a2beb | 2178 | /** |
913ffdb5 | 2179 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 2180 | * @task: target task |
857a2beb TH |
2181 | * @buf: the buffer to write the path into |
2182 | * @buflen: the length of the buffer | |
2183 | * | |
913ffdb5 TH |
2184 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
2185 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
2186 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
2187 | * cgroup controller callbacks. | |
2188 | * | |
e61734c5 | 2189 | * Return value is the same as kernfs_path(). |
857a2beb | 2190 | */ |
e61734c5 | 2191 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 2192 | { |
3dd06ffa | 2193 | struct cgroup_root *root; |
913ffdb5 | 2194 | struct cgroup *cgrp; |
e61734c5 TH |
2195 | int hierarchy_id = 1; |
2196 | char *path = NULL; | |
857a2beb TH |
2197 | |
2198 | mutex_lock(&cgroup_mutex); | |
f0d9a5f1 | 2199 | spin_lock_bh(&css_set_lock); |
857a2beb | 2200 | |
913ffdb5 TH |
2201 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
2202 | ||
857a2beb TH |
2203 | if (root) { |
2204 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 2205 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
2206 | } else { |
2207 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
2208 | if (strlcpy(buf, "/", buflen) < buflen) |
2209 | path = buf; | |
857a2beb TH |
2210 | } |
2211 | ||
f0d9a5f1 | 2212 | spin_unlock_bh(&css_set_lock); |
857a2beb | 2213 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 2214 | return path; |
857a2beb | 2215 | } |
913ffdb5 | 2216 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 2217 | |
b3dc094e | 2218 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 2219 | struct cgroup_taskset { |
b3dc094e TH |
2220 | /* the src and dst cset list running through cset->mg_node */ |
2221 | struct list_head src_csets; | |
2222 | struct list_head dst_csets; | |
2223 | ||
2224 | /* | |
2225 | * Fields for cgroup_taskset_*() iteration. | |
2226 | * | |
2227 | * Before migration is committed, the target migration tasks are on | |
2228 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
2229 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
2230 | * or ->dst_csets depending on whether migration is committed. | |
2231 | * | |
2232 | * ->cur_csets and ->cur_task point to the current task position | |
2233 | * during iteration. | |
2234 | */ | |
2235 | struct list_head *csets; | |
2236 | struct css_set *cur_cset; | |
2237 | struct task_struct *cur_task; | |
2f7ee569 TH |
2238 | }; |
2239 | ||
adaae5dc TH |
2240 | #define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \ |
2241 | .src_csets = LIST_HEAD_INIT(tset.src_csets), \ | |
2242 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \ | |
2243 | .csets = &tset.src_csets, \ | |
2244 | } | |
2245 | ||
2246 | /** | |
2247 | * cgroup_taskset_add - try to add a migration target task to a taskset | |
2248 | * @task: target task | |
2249 | * @tset: target taskset | |
2250 | * | |
2251 | * Add @task, which is a migration target, to @tset. This function becomes | |
2252 | * noop if @task doesn't need to be migrated. @task's css_set should have | |
2253 | * been added as a migration source and @task->cg_list will be moved from | |
2254 | * the css_set's tasks list to mg_tasks one. | |
2255 | */ | |
2256 | static void cgroup_taskset_add(struct task_struct *task, | |
2257 | struct cgroup_taskset *tset) | |
2258 | { | |
2259 | struct css_set *cset; | |
2260 | ||
f0d9a5f1 | 2261 | lockdep_assert_held(&css_set_lock); |
adaae5dc TH |
2262 | |
2263 | /* @task either already exited or can't exit until the end */ | |
2264 | if (task->flags & PF_EXITING) | |
2265 | return; | |
2266 | ||
2267 | /* leave @task alone if post_fork() hasn't linked it yet */ | |
2268 | if (list_empty(&task->cg_list)) | |
2269 | return; | |
2270 | ||
2271 | cset = task_css_set(task); | |
2272 | if (!cset->mg_src_cgrp) | |
2273 | return; | |
2274 | ||
2275 | list_move_tail(&task->cg_list, &cset->mg_tasks); | |
2276 | if (list_empty(&cset->mg_node)) | |
2277 | list_add_tail(&cset->mg_node, &tset->src_csets); | |
2278 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
2279 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
2280 | &tset->dst_csets); | |
2281 | } | |
2282 | ||
2f7ee569 TH |
2283 | /** |
2284 | * cgroup_taskset_first - reset taskset and return the first task | |
2285 | * @tset: taskset of interest | |
2286 | * | |
2287 | * @tset iteration is initialized and the first task is returned. | |
2288 | */ | |
2289 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
2290 | { | |
b3dc094e TH |
2291 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
2292 | tset->cur_task = NULL; | |
2293 | ||
2294 | return cgroup_taskset_next(tset); | |
2f7ee569 | 2295 | } |
2f7ee569 TH |
2296 | |
2297 | /** | |
2298 | * cgroup_taskset_next - iterate to the next task in taskset | |
2299 | * @tset: taskset of interest | |
2300 | * | |
2301 | * Return the next task in @tset. Iteration must have been initialized | |
2302 | * with cgroup_taskset_first(). | |
2303 | */ | |
2304 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
2305 | { | |
b3dc094e TH |
2306 | struct css_set *cset = tset->cur_cset; |
2307 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 2308 | |
b3dc094e TH |
2309 | while (&cset->mg_node != tset->csets) { |
2310 | if (!task) | |
2311 | task = list_first_entry(&cset->mg_tasks, | |
2312 | struct task_struct, cg_list); | |
2313 | else | |
2314 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 2315 | |
b3dc094e TH |
2316 | if (&task->cg_list != &cset->mg_tasks) { |
2317 | tset->cur_cset = cset; | |
2318 | tset->cur_task = task; | |
2319 | return task; | |
2320 | } | |
2f7ee569 | 2321 | |
b3dc094e TH |
2322 | cset = list_next_entry(cset, mg_node); |
2323 | task = NULL; | |
2324 | } | |
2f7ee569 | 2325 | |
b3dc094e | 2326 | return NULL; |
2f7ee569 | 2327 | } |
2f7ee569 | 2328 | |
adaae5dc TH |
2329 | /** |
2330 | * cgroup_taskset_migrate - migrate a taskset to a cgroup | |
2331 | * @tset: taget taskset | |
2332 | * @dst_cgrp: destination cgroup | |
2333 | * | |
2334 | * Migrate tasks in @tset to @dst_cgrp. This function fails iff one of the | |
2335 | * ->can_attach callbacks fails and guarantees that either all or none of | |
2336 | * the tasks in @tset are migrated. @tset is consumed regardless of | |
2337 | * success. | |
2338 | */ | |
2339 | static int cgroup_taskset_migrate(struct cgroup_taskset *tset, | |
2340 | struct cgroup *dst_cgrp) | |
2341 | { | |
2342 | struct cgroup_subsys_state *css, *failed_css = NULL; | |
2343 | struct task_struct *task, *tmp_task; | |
2344 | struct css_set *cset, *tmp_cset; | |
2345 | int i, ret; | |
2346 | ||
2347 | /* methods shouldn't be called if no task is actually migrating */ | |
2348 | if (list_empty(&tset->src_csets)) | |
2349 | return 0; | |
2350 | ||
2351 | /* check that we can legitimately attach to the cgroup */ | |
2352 | for_each_e_css(css, i, dst_cgrp) { | |
2353 | if (css->ss->can_attach) { | |
2354 | ret = css->ss->can_attach(css, tset); | |
2355 | if (ret) { | |
2356 | failed_css = css; | |
2357 | goto out_cancel_attach; | |
2358 | } | |
2359 | } | |
2360 | } | |
2361 | ||
2362 | /* | |
2363 | * Now that we're guaranteed success, proceed to move all tasks to | |
2364 | * the new cgroup. There are no failure cases after here, so this | |
2365 | * is the commit point. | |
2366 | */ | |
f0d9a5f1 | 2367 | spin_lock_bh(&css_set_lock); |
adaae5dc | 2368 | list_for_each_entry(cset, &tset->src_csets, mg_node) { |
f6d7d049 TH |
2369 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) { |
2370 | struct css_set *from_cset = task_css_set(task); | |
2371 | struct css_set *to_cset = cset->mg_dst_cset; | |
2372 | ||
2373 | get_css_set(to_cset); | |
2374 | css_set_move_task(task, from_cset, to_cset, true); | |
2375 | put_css_set_locked(from_cset); | |
2376 | } | |
adaae5dc | 2377 | } |
f0d9a5f1 | 2378 | spin_unlock_bh(&css_set_lock); |
adaae5dc TH |
2379 | |
2380 | /* | |
2381 | * Migration is committed, all target tasks are now on dst_csets. | |
2382 | * Nothing is sensitive to fork() after this point. Notify | |
2383 | * controllers that migration is complete. | |
2384 | */ | |
2385 | tset->csets = &tset->dst_csets; | |
2386 | ||
2387 | for_each_e_css(css, i, dst_cgrp) | |
2388 | if (css->ss->attach) | |
2389 | css->ss->attach(css, tset); | |
2390 | ||
2391 | ret = 0; | |
2392 | goto out_release_tset; | |
2393 | ||
2394 | out_cancel_attach: | |
2395 | for_each_e_css(css, i, dst_cgrp) { | |
2396 | if (css == failed_css) | |
2397 | break; | |
2398 | if (css->ss->cancel_attach) | |
2399 | css->ss->cancel_attach(css, tset); | |
2400 | } | |
2401 | out_release_tset: | |
f0d9a5f1 | 2402 | spin_lock_bh(&css_set_lock); |
adaae5dc TH |
2403 | list_splice_init(&tset->dst_csets, &tset->src_csets); |
2404 | list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { | |
2405 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); | |
2406 | list_del_init(&cset->mg_node); | |
2407 | } | |
f0d9a5f1 | 2408 | spin_unlock_bh(&css_set_lock); |
adaae5dc TH |
2409 | return ret; |
2410 | } | |
2411 | ||
a043e3b2 | 2412 | /** |
1958d2d5 TH |
2413 | * cgroup_migrate_finish - cleanup after attach |
2414 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 2415 | * |
1958d2d5 TH |
2416 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
2417 | * those functions for details. | |
74a1166d | 2418 | */ |
1958d2d5 | 2419 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 2420 | { |
1958d2d5 | 2421 | struct css_set *cset, *tmp_cset; |
74a1166d | 2422 | |
1958d2d5 TH |
2423 | lockdep_assert_held(&cgroup_mutex); |
2424 | ||
f0d9a5f1 | 2425 | spin_lock_bh(&css_set_lock); |
1958d2d5 TH |
2426 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { |
2427 | cset->mg_src_cgrp = NULL; | |
2428 | cset->mg_dst_cset = NULL; | |
2429 | list_del_init(&cset->mg_preload_node); | |
a25eb52e | 2430 | put_css_set_locked(cset); |
1958d2d5 | 2431 | } |
f0d9a5f1 | 2432 | spin_unlock_bh(&css_set_lock); |
1958d2d5 TH |
2433 | } |
2434 | ||
2435 | /** | |
2436 | * cgroup_migrate_add_src - add a migration source css_set | |
2437 | * @src_cset: the source css_set to add | |
2438 | * @dst_cgrp: the destination cgroup | |
2439 | * @preloaded_csets: list of preloaded css_sets | |
2440 | * | |
2441 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
2442 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
2443 | * up by cgroup_migrate_finish(). | |
2444 | * | |
1ed13287 TH |
2445 | * This function may be called without holding cgroup_threadgroup_rwsem |
2446 | * even if the target is a process. Threads may be created and destroyed | |
2447 | * but as long as cgroup_mutex is not dropped, no new css_set can be put | |
2448 | * into play and the preloaded css_sets are guaranteed to cover all | |
2449 | * migrations. | |
1958d2d5 TH |
2450 | */ |
2451 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
2452 | struct cgroup *dst_cgrp, | |
2453 | struct list_head *preloaded_csets) | |
2454 | { | |
2455 | struct cgroup *src_cgrp; | |
2456 | ||
2457 | lockdep_assert_held(&cgroup_mutex); | |
f0d9a5f1 | 2458 | lockdep_assert_held(&css_set_lock); |
1958d2d5 TH |
2459 | |
2460 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
2461 | ||
1958d2d5 TH |
2462 | if (!list_empty(&src_cset->mg_preload_node)) |
2463 | return; | |
2464 | ||
2465 | WARN_ON(src_cset->mg_src_cgrp); | |
2466 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
2467 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
2468 | ||
2469 | src_cset->mg_src_cgrp = src_cgrp; | |
2470 | get_css_set(src_cset); | |
2471 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
2472 | } | |
2473 | ||
2474 | /** | |
2475 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
f817de98 | 2476 | * @dst_cgrp: the destination cgroup (may be %NULL) |
1958d2d5 TH |
2477 | * @preloaded_csets: list of preloaded source css_sets |
2478 | * | |
2479 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
2480 | * have been preloaded to @preloaded_csets. This function looks up and | |
f817de98 TH |
2481 | * pins all destination css_sets, links each to its source, and append them |
2482 | * to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each | |
2483 | * source css_set is assumed to be its cgroup on the default hierarchy. | |
1958d2d5 TH |
2484 | * |
2485 | * This function must be called after cgroup_migrate_add_src() has been | |
2486 | * called on each migration source css_set. After migration is performed | |
2487 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
2488 | * @preloaded_csets. | |
2489 | */ | |
2490 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
2491 | struct list_head *preloaded_csets) | |
2492 | { | |
2493 | LIST_HEAD(csets); | |
f817de98 | 2494 | struct css_set *src_cset, *tmp_cset; |
1958d2d5 TH |
2495 | |
2496 | lockdep_assert_held(&cgroup_mutex); | |
2497 | ||
f8f22e53 TH |
2498 | /* |
2499 | * Except for the root, child_subsys_mask must be zero for a cgroup | |
2500 | * with tasks so that child cgroups don't compete against tasks. | |
2501 | */ | |
d51f39b0 | 2502 | if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && |
f8f22e53 TH |
2503 | dst_cgrp->child_subsys_mask) |
2504 | return -EBUSY; | |
2505 | ||
1958d2d5 | 2506 | /* look up the dst cset for each src cset and link it to src */ |
f817de98 | 2507 | list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { |
1958d2d5 TH |
2508 | struct css_set *dst_cset; |
2509 | ||
f817de98 TH |
2510 | dst_cset = find_css_set(src_cset, |
2511 | dst_cgrp ?: src_cset->dfl_cgrp); | |
1958d2d5 TH |
2512 | if (!dst_cset) |
2513 | goto err; | |
2514 | ||
2515 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
f817de98 TH |
2516 | |
2517 | /* | |
2518 | * If src cset equals dst, it's noop. Drop the src. | |
2519 | * cgroup_migrate() will skip the cset too. Note that we | |
2520 | * can't handle src == dst as some nodes are used by both. | |
2521 | */ | |
2522 | if (src_cset == dst_cset) { | |
2523 | src_cset->mg_src_cgrp = NULL; | |
2524 | list_del_init(&src_cset->mg_preload_node); | |
a25eb52e ZL |
2525 | put_css_set(src_cset); |
2526 | put_css_set(dst_cset); | |
f817de98 TH |
2527 | continue; |
2528 | } | |
2529 | ||
1958d2d5 TH |
2530 | src_cset->mg_dst_cset = dst_cset; |
2531 | ||
2532 | if (list_empty(&dst_cset->mg_preload_node)) | |
2533 | list_add(&dst_cset->mg_preload_node, &csets); | |
2534 | else | |
a25eb52e | 2535 | put_css_set(dst_cset); |
1958d2d5 TH |
2536 | } |
2537 | ||
f817de98 | 2538 | list_splice_tail(&csets, preloaded_csets); |
1958d2d5 TH |
2539 | return 0; |
2540 | err: | |
2541 | cgroup_migrate_finish(&csets); | |
2542 | return -ENOMEM; | |
2543 | } | |
2544 | ||
2545 | /** | |
2546 | * cgroup_migrate - migrate a process or task to a cgroup | |
1958d2d5 TH |
2547 | * @leader: the leader of the process or the task to migrate |
2548 | * @threadgroup: whether @leader points to the whole process or a single task | |
9af2ec45 | 2549 | * @cgrp: the destination cgroup |
1958d2d5 TH |
2550 | * |
2551 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1ed13287 | 2552 | * process, the caller must be holding cgroup_threadgroup_rwsem. The |
1958d2d5 TH |
2553 | * caller is also responsible for invoking cgroup_migrate_add_src() and |
2554 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
2555 | * function and following up with cgroup_migrate_finish(). | |
2556 | * | |
2557 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
2558 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
2559 | * failure, when migrating multiple targets, the success or failure can be | |
2560 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
2561 | * actually starting migrating. | |
2562 | */ | |
9af2ec45 TH |
2563 | static int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
2564 | struct cgroup *cgrp) | |
74a1166d | 2565 | { |
adaae5dc TH |
2566 | struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
2567 | struct task_struct *task; | |
74a1166d | 2568 | |
fb5d2b4c MSB |
2569 | /* |
2570 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2571 | * already PF_EXITING could be freed from underneath us unless we | |
2572 | * take an rcu_read_lock. | |
2573 | */ | |
f0d9a5f1 | 2574 | spin_lock_bh(&css_set_lock); |
fb5d2b4c | 2575 | rcu_read_lock(); |
9db8de37 | 2576 | task = leader; |
74a1166d | 2577 | do { |
adaae5dc | 2578 | cgroup_taskset_add(task, &tset); |
081aa458 LZ |
2579 | if (!threadgroup) |
2580 | break; | |
9db8de37 | 2581 | } while_each_thread(leader, task); |
fb5d2b4c | 2582 | rcu_read_unlock(); |
f0d9a5f1 | 2583 | spin_unlock_bh(&css_set_lock); |
74a1166d | 2584 | |
adaae5dc | 2585 | return cgroup_taskset_migrate(&tset, cgrp); |
74a1166d BB |
2586 | } |
2587 | ||
1958d2d5 TH |
2588 | /** |
2589 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2590 | * @dst_cgrp: the cgroup to attach to | |
2591 | * @leader: the task or the leader of the threadgroup to be attached | |
2592 | * @threadgroup: attach the whole threadgroup? | |
2593 | * | |
1ed13287 | 2594 | * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
1958d2d5 TH |
2595 | */ |
2596 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2597 | struct task_struct *leader, bool threadgroup) | |
2598 | { | |
2599 | LIST_HEAD(preloaded_csets); | |
2600 | struct task_struct *task; | |
2601 | int ret; | |
2602 | ||
2603 | /* look up all src csets */ | |
f0d9a5f1 | 2604 | spin_lock_bh(&css_set_lock); |
1958d2d5 TH |
2605 | rcu_read_lock(); |
2606 | task = leader; | |
2607 | do { | |
2608 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2609 | &preloaded_csets); | |
2610 | if (!threadgroup) | |
2611 | break; | |
2612 | } while_each_thread(leader, task); | |
2613 | rcu_read_unlock(); | |
f0d9a5f1 | 2614 | spin_unlock_bh(&css_set_lock); |
1958d2d5 TH |
2615 | |
2616 | /* prepare dst csets and commit */ | |
2617 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2618 | if (!ret) | |
9af2ec45 | 2619 | ret = cgroup_migrate(leader, threadgroup, dst_cgrp); |
1958d2d5 TH |
2620 | |
2621 | cgroup_migrate_finish(&preloaded_csets); | |
2622 | return ret; | |
74a1166d BB |
2623 | } |
2624 | ||
187fe840 TH |
2625 | static int cgroup_procs_write_permission(struct task_struct *task, |
2626 | struct cgroup *dst_cgrp, | |
2627 | struct kernfs_open_file *of) | |
dedf22e9 TH |
2628 | { |
2629 | const struct cred *cred = current_cred(); | |
2630 | const struct cred *tcred = get_task_cred(task); | |
2631 | int ret = 0; | |
2632 | ||
2633 | /* | |
2634 | * even if we're attaching all tasks in the thread group, we only | |
2635 | * need to check permissions on one of them. | |
2636 | */ | |
2637 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && | |
2638 | !uid_eq(cred->euid, tcred->uid) && | |
2639 | !uid_eq(cred->euid, tcred->suid)) | |
2640 | ret = -EACCES; | |
2641 | ||
187fe840 TH |
2642 | if (!ret && cgroup_on_dfl(dst_cgrp)) { |
2643 | struct super_block *sb = of->file->f_path.dentry->d_sb; | |
2644 | struct cgroup *cgrp; | |
2645 | struct inode *inode; | |
2646 | ||
f0d9a5f1 | 2647 | spin_lock_bh(&css_set_lock); |
187fe840 | 2648 | cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); |
f0d9a5f1 | 2649 | spin_unlock_bh(&css_set_lock); |
187fe840 TH |
2650 | |
2651 | while (!cgroup_is_descendant(dst_cgrp, cgrp)) | |
2652 | cgrp = cgroup_parent(cgrp); | |
2653 | ||
2654 | ret = -ENOMEM; | |
6f60eade | 2655 | inode = kernfs_get_inode(sb, cgrp->procs_file.kn); |
187fe840 TH |
2656 | if (inode) { |
2657 | ret = inode_permission(inode, MAY_WRITE); | |
2658 | iput(inode); | |
2659 | } | |
2660 | } | |
2661 | ||
dedf22e9 TH |
2662 | put_cred(tcred); |
2663 | return ret; | |
2664 | } | |
2665 | ||
74a1166d BB |
2666 | /* |
2667 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2668 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2669 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2670 | */ |
acbef755 TH |
2671 | static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
2672 | size_t nbytes, loff_t off, bool threadgroup) | |
bbcb81d0 | 2673 | { |
bbcb81d0 | 2674 | struct task_struct *tsk; |
e76ecaee | 2675 | struct cgroup *cgrp; |
acbef755 | 2676 | pid_t pid; |
bbcb81d0 PM |
2677 | int ret; |
2678 | ||
acbef755 TH |
2679 | if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
2680 | return -EINVAL; | |
2681 | ||
e76ecaee TH |
2682 | cgrp = cgroup_kn_lock_live(of->kn); |
2683 | if (!cgrp) | |
74a1166d BB |
2684 | return -ENODEV; |
2685 | ||
3014dde7 | 2686 | percpu_down_write(&cgroup_threadgroup_rwsem); |
b78949eb | 2687 | rcu_read_lock(); |
bbcb81d0 | 2688 | if (pid) { |
73507f33 | 2689 | tsk = find_task_by_vpid(pid); |
74a1166d | 2690 | if (!tsk) { |
dd4b0a46 | 2691 | ret = -ESRCH; |
3014dde7 | 2692 | goto out_unlock_rcu; |
bbcb81d0 | 2693 | } |
dedf22e9 | 2694 | } else { |
b78949eb | 2695 | tsk = current; |
dedf22e9 | 2696 | } |
cd3d0952 TH |
2697 | |
2698 | if (threadgroup) | |
b78949eb | 2699 | tsk = tsk->group_leader; |
c4c27fbd MG |
2700 | |
2701 | /* | |
14a40ffc | 2702 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2703 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2704 | * with no rt_runtime allocated. Just say no. | |
2705 | */ | |
14a40ffc | 2706 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd | 2707 | ret = -EINVAL; |
3014dde7 | 2708 | goto out_unlock_rcu; |
c4c27fbd MG |
2709 | } |
2710 | ||
b78949eb MSB |
2711 | get_task_struct(tsk); |
2712 | rcu_read_unlock(); | |
2713 | ||
187fe840 | 2714 | ret = cgroup_procs_write_permission(tsk, cgrp, of); |
dedf22e9 TH |
2715 | if (!ret) |
2716 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
081aa458 | 2717 | |
f9f9e7b7 | 2718 | put_task_struct(tsk); |
3014dde7 TH |
2719 | goto out_unlock_threadgroup; |
2720 | ||
2721 | out_unlock_rcu: | |
2722 | rcu_read_unlock(); | |
2723 | out_unlock_threadgroup: | |
2724 | percpu_up_write(&cgroup_threadgroup_rwsem); | |
e76ecaee | 2725 | cgroup_kn_unlock(of->kn); |
acbef755 | 2726 | return ret ?: nbytes; |
bbcb81d0 PM |
2727 | } |
2728 | ||
7ae1bad9 TH |
2729 | /** |
2730 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2731 | * @from: attach to all cgroups of a given task | |
2732 | * @tsk: the task to be attached | |
2733 | */ | |
2734 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2735 | { | |
3dd06ffa | 2736 | struct cgroup_root *root; |
7ae1bad9 TH |
2737 | int retval = 0; |
2738 | ||
47cfcd09 | 2739 | mutex_lock(&cgroup_mutex); |
985ed670 | 2740 | for_each_root(root) { |
96d365e0 TH |
2741 | struct cgroup *from_cgrp; |
2742 | ||
3dd06ffa | 2743 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2744 | continue; |
2745 | ||
f0d9a5f1 | 2746 | spin_lock_bh(&css_set_lock); |
96d365e0 | 2747 | from_cgrp = task_cgroup_from_root(from, root); |
f0d9a5f1 | 2748 | spin_unlock_bh(&css_set_lock); |
7ae1bad9 | 2749 | |
6f4b7e63 | 2750 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2751 | if (retval) |
2752 | break; | |
2753 | } | |
47cfcd09 | 2754 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2755 | |
2756 | return retval; | |
2757 | } | |
2758 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2759 | ||
acbef755 TH |
2760 | static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
2761 | char *buf, size_t nbytes, loff_t off) | |
74a1166d | 2762 | { |
acbef755 | 2763 | return __cgroup_procs_write(of, buf, nbytes, off, false); |
74a1166d BB |
2764 | } |
2765 | ||
acbef755 TH |
2766 | static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
2767 | char *buf, size_t nbytes, loff_t off) | |
af351026 | 2768 | { |
acbef755 | 2769 | return __cgroup_procs_write(of, buf, nbytes, off, true); |
af351026 PM |
2770 | } |
2771 | ||
451af504 TH |
2772 | static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
2773 | char *buf, size_t nbytes, loff_t off) | |
e788e066 | 2774 | { |
e76ecaee | 2775 | struct cgroup *cgrp; |
5f469907 | 2776 | |
e76ecaee | 2777 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
5f469907 | 2778 | |
e76ecaee TH |
2779 | cgrp = cgroup_kn_lock_live(of->kn); |
2780 | if (!cgrp) | |
e788e066 | 2781 | return -ENODEV; |
69e943b7 | 2782 | spin_lock(&release_agent_path_lock); |
e76ecaee TH |
2783 | strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
2784 | sizeof(cgrp->root->release_agent_path)); | |
69e943b7 | 2785 | spin_unlock(&release_agent_path_lock); |
e76ecaee | 2786 | cgroup_kn_unlock(of->kn); |
451af504 | 2787 | return nbytes; |
e788e066 PM |
2788 | } |
2789 | ||
2da8ca82 | 2790 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2791 | { |
2da8ca82 | 2792 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2793 | |
46cfeb04 | 2794 | spin_lock(&release_agent_path_lock); |
e788e066 | 2795 | seq_puts(seq, cgrp->root->release_agent_path); |
46cfeb04 | 2796 | spin_unlock(&release_agent_path_lock); |
e788e066 | 2797 | seq_putc(seq, '\n'); |
e788e066 PM |
2798 | return 0; |
2799 | } | |
2800 | ||
2da8ca82 | 2801 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2802 | { |
c1d5d42e | 2803 | seq_puts(seq, "0\n"); |
e788e066 PM |
2804 | return 0; |
2805 | } | |
2806 | ||
8ab456ac | 2807 | static void cgroup_print_ss_mask(struct seq_file *seq, unsigned long ss_mask) |
355e0c48 | 2808 | { |
f8f22e53 TH |
2809 | struct cgroup_subsys *ss; |
2810 | bool printed = false; | |
2811 | int ssid; | |
a742c59d | 2812 | |
a966a4ed AS |
2813 | for_each_subsys_which(ss, ssid, &ss_mask) { |
2814 | if (printed) | |
2815 | seq_putc(seq, ' '); | |
2816 | seq_printf(seq, "%s", ss->name); | |
2817 | printed = true; | |
e73d2c61 | 2818 | } |
f8f22e53 TH |
2819 | if (printed) |
2820 | seq_putc(seq, '\n'); | |
355e0c48 PM |
2821 | } |
2822 | ||
f8f22e53 TH |
2823 | /* show controllers which are currently attached to the default hierarchy */ |
2824 | static int cgroup_root_controllers_show(struct seq_file *seq, void *v) | |
db3b1497 | 2825 | { |
f8f22e53 TH |
2826 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2827 | ||
5533e011 TH |
2828 | cgroup_print_ss_mask(seq, cgrp->root->subsys_mask & |
2829 | ~cgrp_dfl_root_inhibit_ss_mask); | |
f8f22e53 | 2830 | return 0; |
db3b1497 PM |
2831 | } |
2832 | ||
f8f22e53 TH |
2833 | /* show controllers which are enabled from the parent */ |
2834 | static int cgroup_controllers_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2835 | { |
f8f22e53 TH |
2836 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2837 | ||
667c2491 | 2838 | cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control); |
f8f22e53 | 2839 | return 0; |
ddbcc7e8 PM |
2840 | } |
2841 | ||
f8f22e53 TH |
2842 | /* show controllers which are enabled for a given cgroup's children */ |
2843 | static int cgroup_subtree_control_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2844 | { |
f8f22e53 TH |
2845 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2846 | ||
667c2491 | 2847 | cgroup_print_ss_mask(seq, cgrp->subtree_control); |
f8f22e53 TH |
2848 | return 0; |
2849 | } | |
2850 | ||
2851 | /** | |
2852 | * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy | |
2853 | * @cgrp: root of the subtree to update csses for | |
2854 | * | |
2855 | * @cgrp's child_subsys_mask has changed and its subtree's (self excluded) | |
2856 | * css associations need to be updated accordingly. This function looks up | |
2857 | * all css_sets which are attached to the subtree, creates the matching | |
2858 | * updated css_sets and migrates the tasks to the new ones. | |
2859 | */ | |
2860 | static int cgroup_update_dfl_csses(struct cgroup *cgrp) | |
2861 | { | |
2862 | LIST_HEAD(preloaded_csets); | |
10265075 | 2863 | struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
f8f22e53 TH |
2864 | struct cgroup_subsys_state *css; |
2865 | struct css_set *src_cset; | |
2866 | int ret; | |
2867 | ||
f8f22e53 TH |
2868 | lockdep_assert_held(&cgroup_mutex); |
2869 | ||
3014dde7 TH |
2870 | percpu_down_write(&cgroup_threadgroup_rwsem); |
2871 | ||
f8f22e53 | 2872 | /* look up all csses currently attached to @cgrp's subtree */ |
f0d9a5f1 | 2873 | spin_lock_bh(&css_set_lock); |
f8f22e53 TH |
2874 | css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) { |
2875 | struct cgrp_cset_link *link; | |
2876 | ||
2877 | /* self is not affected by child_subsys_mask change */ | |
2878 | if (css->cgroup == cgrp) | |
2879 | continue; | |
2880 | ||
2881 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) | |
2882 | cgroup_migrate_add_src(link->cset, cgrp, | |
2883 | &preloaded_csets); | |
2884 | } | |
f0d9a5f1 | 2885 | spin_unlock_bh(&css_set_lock); |
f8f22e53 TH |
2886 | |
2887 | /* NULL dst indicates self on default hierarchy */ | |
2888 | ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets); | |
2889 | if (ret) | |
2890 | goto out_finish; | |
2891 | ||
f0d9a5f1 | 2892 | spin_lock_bh(&css_set_lock); |
f8f22e53 | 2893 | list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { |
10265075 | 2894 | struct task_struct *task, *ntask; |
f8f22e53 TH |
2895 | |
2896 | /* src_csets precede dst_csets, break on the first dst_cset */ | |
2897 | if (!src_cset->mg_src_cgrp) | |
2898 | break; | |
2899 | ||
10265075 TH |
2900 | /* all tasks in src_csets need to be migrated */ |
2901 | list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) | |
2902 | cgroup_taskset_add(task, &tset); | |
f8f22e53 | 2903 | } |
f0d9a5f1 | 2904 | spin_unlock_bh(&css_set_lock); |
f8f22e53 | 2905 | |
10265075 | 2906 | ret = cgroup_taskset_migrate(&tset, cgrp); |
f8f22e53 TH |
2907 | out_finish: |
2908 | cgroup_migrate_finish(&preloaded_csets); | |
3014dde7 | 2909 | percpu_up_write(&cgroup_threadgroup_rwsem); |
f8f22e53 TH |
2910 | return ret; |
2911 | } | |
2912 | ||
2913 | /* change the enabled child controllers for a cgroup in the default hierarchy */ | |
451af504 TH |
2914 | static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
2915 | char *buf, size_t nbytes, | |
2916 | loff_t off) | |
f8f22e53 | 2917 | { |
8ab456ac AS |
2918 | unsigned long enable = 0, disable = 0; |
2919 | unsigned long css_enable, css_disable, old_sc, new_sc, old_ss, new_ss; | |
a9746d8d | 2920 | struct cgroup *cgrp, *child; |
f8f22e53 | 2921 | struct cgroup_subsys *ss; |
451af504 | 2922 | char *tok; |
f8f22e53 TH |
2923 | int ssid, ret; |
2924 | ||
2925 | /* | |
d37167ab TH |
2926 | * Parse input - space separated list of subsystem names prefixed |
2927 | * with either + or -. | |
f8f22e53 | 2928 | */ |
451af504 TH |
2929 | buf = strstrip(buf); |
2930 | while ((tok = strsep(&buf, " "))) { | |
a966a4ed AS |
2931 | unsigned long tmp_ss_mask = ~cgrp_dfl_root_inhibit_ss_mask; |
2932 | ||
d37167ab TH |
2933 | if (tok[0] == '\0') |
2934 | continue; | |
a966a4ed | 2935 | for_each_subsys_which(ss, ssid, &tmp_ss_mask) { |
fc5ed1e9 TH |
2936 | if (!cgroup_ssid_enabled(ssid) || |
2937 | strcmp(tok + 1, ss->name)) | |
f8f22e53 TH |
2938 | continue; |
2939 | ||
2940 | if (*tok == '+') { | |
7d331fa9 TH |
2941 | enable |= 1 << ssid; |
2942 | disable &= ~(1 << ssid); | |
f8f22e53 | 2943 | } else if (*tok == '-') { |
7d331fa9 TH |
2944 | disable |= 1 << ssid; |
2945 | enable &= ~(1 << ssid); | |
f8f22e53 TH |
2946 | } else { |
2947 | return -EINVAL; | |
2948 | } | |
2949 | break; | |
2950 | } | |
2951 | if (ssid == CGROUP_SUBSYS_COUNT) | |
2952 | return -EINVAL; | |
2953 | } | |
2954 | ||
a9746d8d TH |
2955 | cgrp = cgroup_kn_lock_live(of->kn); |
2956 | if (!cgrp) | |
2957 | return -ENODEV; | |
f8f22e53 TH |
2958 | |
2959 | for_each_subsys(ss, ssid) { | |
2960 | if (enable & (1 << ssid)) { | |
667c2491 | 2961 | if (cgrp->subtree_control & (1 << ssid)) { |
f8f22e53 TH |
2962 | enable &= ~(1 << ssid); |
2963 | continue; | |
2964 | } | |
2965 | ||
c29adf24 TH |
2966 | /* unavailable or not enabled on the parent? */ |
2967 | if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) || | |
2968 | (cgroup_parent(cgrp) && | |
667c2491 | 2969 | !(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) { |
c29adf24 TH |
2970 | ret = -ENOENT; |
2971 | goto out_unlock; | |
2972 | } | |
f8f22e53 | 2973 | } else if (disable & (1 << ssid)) { |
667c2491 | 2974 | if (!(cgrp->subtree_control & (1 << ssid))) { |
f8f22e53 TH |
2975 | disable &= ~(1 << ssid); |
2976 | continue; | |
2977 | } | |
2978 | ||
2979 | /* a child has it enabled? */ | |
2980 | cgroup_for_each_live_child(child, cgrp) { | |
667c2491 | 2981 | if (child->subtree_control & (1 << ssid)) { |
f8f22e53 | 2982 | ret = -EBUSY; |
ddab2b6e | 2983 | goto out_unlock; |
f8f22e53 TH |
2984 | } |
2985 | } | |
2986 | } | |
2987 | } | |
2988 | ||
2989 | if (!enable && !disable) { | |
2990 | ret = 0; | |
ddab2b6e | 2991 | goto out_unlock; |
f8f22e53 TH |
2992 | } |
2993 | ||
2994 | /* | |
667c2491 | 2995 | * Except for the root, subtree_control must be zero for a cgroup |
f8f22e53 TH |
2996 | * with tasks so that child cgroups don't compete against tasks. |
2997 | */ | |
d51f39b0 | 2998 | if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) { |
f8f22e53 TH |
2999 | ret = -EBUSY; |
3000 | goto out_unlock; | |
3001 | } | |
3002 | ||
3003 | /* | |
f63070d3 TH |
3004 | * Update subsys masks and calculate what needs to be done. More |
3005 | * subsystems than specified may need to be enabled or disabled | |
3006 | * depending on subsystem dependencies. | |
3007 | */ | |
755bf5ee TH |
3008 | old_sc = cgrp->subtree_control; |
3009 | old_ss = cgrp->child_subsys_mask; | |
3010 | new_sc = (old_sc | enable) & ~disable; | |
3011 | new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc); | |
f63070d3 | 3012 | |
755bf5ee TH |
3013 | css_enable = ~old_ss & new_ss; |
3014 | css_disable = old_ss & ~new_ss; | |
f63070d3 TH |
3015 | enable |= css_enable; |
3016 | disable |= css_disable; | |
c29adf24 | 3017 | |
db6e3053 TH |
3018 | /* |
3019 | * Because css offlining is asynchronous, userland might try to | |
3020 | * re-enable the same controller while the previous instance is | |
3021 | * still around. In such cases, wait till it's gone using | |
3022 | * offline_waitq. | |
3023 | */ | |
a966a4ed | 3024 | for_each_subsys_which(ss, ssid, &css_enable) { |
db6e3053 TH |
3025 | cgroup_for_each_live_child(child, cgrp) { |
3026 | DEFINE_WAIT(wait); | |
3027 | ||
3028 | if (!cgroup_css(child, ss)) | |
3029 | continue; | |
3030 | ||
3031 | cgroup_get(child); | |
3032 | prepare_to_wait(&child->offline_waitq, &wait, | |
3033 | TASK_UNINTERRUPTIBLE); | |
3034 | cgroup_kn_unlock(of->kn); | |
3035 | schedule(); | |
3036 | finish_wait(&child->offline_waitq, &wait); | |
3037 | cgroup_put(child); | |
3038 | ||
3039 | return restart_syscall(); | |
3040 | } | |
3041 | } | |
3042 | ||
755bf5ee TH |
3043 | cgrp->subtree_control = new_sc; |
3044 | cgrp->child_subsys_mask = new_ss; | |
3045 | ||
f63070d3 TH |
3046 | /* |
3047 | * Create new csses or make the existing ones visible. A css is | |
3048 | * created invisible if it's being implicitly enabled through | |
3049 | * dependency. An invisible css is made visible when the userland | |
3050 | * explicitly enables it. | |
f8f22e53 TH |
3051 | */ |
3052 | for_each_subsys(ss, ssid) { | |
3053 | if (!(enable & (1 << ssid))) | |
3054 | continue; | |
3055 | ||
3056 | cgroup_for_each_live_child(child, cgrp) { | |
f63070d3 TH |
3057 | if (css_enable & (1 << ssid)) |
3058 | ret = create_css(child, ss, | |
3059 | cgrp->subtree_control & (1 << ssid)); | |
3060 | else | |
4df8dc90 TH |
3061 | ret = css_populate_dir(cgroup_css(child, ss), |
3062 | NULL); | |
f8f22e53 TH |
3063 | if (ret) |
3064 | goto err_undo_css; | |
3065 | } | |
3066 | } | |
3067 | ||
c29adf24 TH |
3068 | /* |
3069 | * At this point, cgroup_e_css() results reflect the new csses | |
3070 | * making the following cgroup_update_dfl_csses() properly update | |
3071 | * css associations of all tasks in the subtree. | |
3072 | */ | |
f8f22e53 TH |
3073 | ret = cgroup_update_dfl_csses(cgrp); |
3074 | if (ret) | |
3075 | goto err_undo_css; | |
3076 | ||
f63070d3 TH |
3077 | /* |
3078 | * All tasks are migrated out of disabled csses. Kill or hide | |
3079 | * them. A css is hidden when the userland requests it to be | |
b4536f0c TH |
3080 | * disabled while other subsystems are still depending on it. The |
3081 | * css must not actively control resources and be in the vanilla | |
3082 | * state if it's made visible again later. Controllers which may | |
3083 | * be depended upon should provide ->css_reset() for this purpose. | |
f63070d3 | 3084 | */ |
f8f22e53 TH |
3085 | for_each_subsys(ss, ssid) { |
3086 | if (!(disable & (1 << ssid))) | |
3087 | continue; | |
3088 | ||
f63070d3 | 3089 | cgroup_for_each_live_child(child, cgrp) { |
b4536f0c TH |
3090 | struct cgroup_subsys_state *css = cgroup_css(child, ss); |
3091 | ||
3092 | if (css_disable & (1 << ssid)) { | |
3093 | kill_css(css); | |
3094 | } else { | |
4df8dc90 | 3095 | css_clear_dir(css, NULL); |
b4536f0c TH |
3096 | if (ss->css_reset) |
3097 | ss->css_reset(css); | |
3098 | } | |
f63070d3 | 3099 | } |
f8f22e53 TH |
3100 | } |
3101 | ||
56c807ba TH |
3102 | /* |
3103 | * The effective csses of all the descendants (excluding @cgrp) may | |
3104 | * have changed. Subsystems can optionally subscribe to this event | |
3105 | * by implementing ->css_e_css_changed() which is invoked if any of | |
3106 | * the effective csses seen from the css's cgroup may have changed. | |
3107 | */ | |
3108 | for_each_subsys(ss, ssid) { | |
3109 | struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss); | |
3110 | struct cgroup_subsys_state *css; | |
3111 | ||
3112 | if (!ss->css_e_css_changed || !this_css) | |
3113 | continue; | |
3114 | ||
3115 | css_for_each_descendant_pre(css, this_css) | |
3116 | if (css != this_css) | |
3117 | ss->css_e_css_changed(css); | |
3118 | } | |
3119 | ||
f8f22e53 TH |
3120 | kernfs_activate(cgrp->kn); |
3121 | ret = 0; | |
3122 | out_unlock: | |
a9746d8d | 3123 | cgroup_kn_unlock(of->kn); |
451af504 | 3124 | return ret ?: nbytes; |
f8f22e53 TH |
3125 | |
3126 | err_undo_css: | |
755bf5ee TH |
3127 | cgrp->subtree_control = old_sc; |
3128 | cgrp->child_subsys_mask = old_ss; | |
f8f22e53 TH |
3129 | |
3130 | for_each_subsys(ss, ssid) { | |
3131 | if (!(enable & (1 << ssid))) | |
3132 | continue; | |
3133 | ||
3134 | cgroup_for_each_live_child(child, cgrp) { | |
3135 | struct cgroup_subsys_state *css = cgroup_css(child, ss); | |
f63070d3 TH |
3136 | |
3137 | if (!css) | |
3138 | continue; | |
3139 | ||
3140 | if (css_enable & (1 << ssid)) | |
f8f22e53 | 3141 | kill_css(css); |
f63070d3 | 3142 | else |
4df8dc90 | 3143 | css_clear_dir(css, NULL); |
f8f22e53 TH |
3144 | } |
3145 | } | |
3146 | goto out_unlock; | |
3147 | } | |
3148 | ||
4a07c222 | 3149 | static int cgroup_events_show(struct seq_file *seq, void *v) |
842b597e | 3150 | { |
4a07c222 | 3151 | seq_printf(seq, "populated %d\n", |
27bd4dbb | 3152 | cgroup_is_populated(seq_css(seq)->cgroup)); |
842b597e TH |
3153 | return 0; |
3154 | } | |
3155 | ||
2bd59d48 TH |
3156 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
3157 | size_t nbytes, loff_t off) | |
355e0c48 | 3158 | { |
2bd59d48 TH |
3159 | struct cgroup *cgrp = of->kn->parent->priv; |
3160 | struct cftype *cft = of->kn->priv; | |
3161 | struct cgroup_subsys_state *css; | |
a742c59d | 3162 | int ret; |
355e0c48 | 3163 | |
b4168640 TH |
3164 | if (cft->write) |
3165 | return cft->write(of, buf, nbytes, off); | |
3166 | ||
2bd59d48 TH |
3167 | /* |
3168 | * kernfs guarantees that a file isn't deleted with operations in | |
3169 | * flight, which means that the matching css is and stays alive and | |
3170 | * doesn't need to be pinned. The RCU locking is not necessary | |
3171 | * either. It's just for the convenience of using cgroup_css(). | |
3172 | */ | |
3173 | rcu_read_lock(); | |
3174 | css = cgroup_css(cgrp, cft->ss); | |
3175 | rcu_read_unlock(); | |
a742c59d | 3176 | |
451af504 | 3177 | if (cft->write_u64) { |
a742c59d TH |
3178 | unsigned long long v; |
3179 | ret = kstrtoull(buf, 0, &v); | |
3180 | if (!ret) | |
3181 | ret = cft->write_u64(css, cft, v); | |
3182 | } else if (cft->write_s64) { | |
3183 | long long v; | |
3184 | ret = kstrtoll(buf, 0, &v); | |
3185 | if (!ret) | |
3186 | ret = cft->write_s64(css, cft, v); | |
e73d2c61 | 3187 | } else { |
a742c59d | 3188 | ret = -EINVAL; |
e73d2c61 | 3189 | } |
2bd59d48 | 3190 | |
a742c59d | 3191 | return ret ?: nbytes; |
355e0c48 PM |
3192 | } |
3193 | ||
6612f05b | 3194 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 3195 | { |
2bd59d48 | 3196 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
3197 | } |
3198 | ||
6612f05b | 3199 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 3200 | { |
2bd59d48 | 3201 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
3202 | } |
3203 | ||
6612f05b | 3204 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 3205 | { |
2bd59d48 | 3206 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
3207 | } |
3208 | ||
91796569 | 3209 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 3210 | { |
7da11279 TH |
3211 | struct cftype *cft = seq_cft(m); |
3212 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 3213 | |
2da8ca82 TH |
3214 | if (cft->seq_show) |
3215 | return cft->seq_show(m, arg); | |
e73d2c61 | 3216 | |
f4c753b7 | 3217 | if (cft->read_u64) |
896f5199 TH |
3218 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
3219 | else if (cft->read_s64) | |
3220 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
3221 | else | |
3222 | return -EINVAL; | |
3223 | return 0; | |
91796569 PM |
3224 | } |
3225 | ||
2bd59d48 TH |
3226 | static struct kernfs_ops cgroup_kf_single_ops = { |
3227 | .atomic_write_len = PAGE_SIZE, | |
3228 | .write = cgroup_file_write, | |
3229 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
3230 | }; |
3231 | ||
2bd59d48 TH |
3232 | static struct kernfs_ops cgroup_kf_ops = { |
3233 | .atomic_write_len = PAGE_SIZE, | |
3234 | .write = cgroup_file_write, | |
3235 | .seq_start = cgroup_seqfile_start, | |
3236 | .seq_next = cgroup_seqfile_next, | |
3237 | .seq_stop = cgroup_seqfile_stop, | |
3238 | .seq_show = cgroup_seqfile_show, | |
3239 | }; | |
ddbcc7e8 PM |
3240 | |
3241 | /* | |
3242 | * cgroup_rename - Only allow simple rename of directories in place. | |
3243 | */ | |
2bd59d48 TH |
3244 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
3245 | const char *new_name_str) | |
ddbcc7e8 | 3246 | { |
2bd59d48 | 3247 | struct cgroup *cgrp = kn->priv; |
65dff759 | 3248 | int ret; |
65dff759 | 3249 | |
2bd59d48 | 3250 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 3251 | return -ENOTDIR; |
2bd59d48 | 3252 | if (kn->parent != new_parent) |
ddbcc7e8 | 3253 | return -EIO; |
65dff759 | 3254 | |
6db8e85c TH |
3255 | /* |
3256 | * This isn't a proper migration and its usefulness is very | |
aa6ec29b | 3257 | * limited. Disallow on the default hierarchy. |
6db8e85c | 3258 | */ |
aa6ec29b | 3259 | if (cgroup_on_dfl(cgrp)) |
6db8e85c | 3260 | return -EPERM; |
099fca32 | 3261 | |
e1b2dc17 | 3262 | /* |
8353da1f | 3263 | * We're gonna grab cgroup_mutex which nests outside kernfs |
e1b2dc17 | 3264 | * active_ref. kernfs_rename() doesn't require active_ref |
8353da1f | 3265 | * protection. Break them before grabbing cgroup_mutex. |
e1b2dc17 TH |
3266 | */ |
3267 | kernfs_break_active_protection(new_parent); | |
3268 | kernfs_break_active_protection(kn); | |
099fca32 | 3269 | |
2bd59d48 | 3270 | mutex_lock(&cgroup_mutex); |
099fca32 | 3271 | |
2bd59d48 | 3272 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 3273 | |
2bd59d48 | 3274 | mutex_unlock(&cgroup_mutex); |
e1b2dc17 TH |
3275 | |
3276 | kernfs_unbreak_active_protection(kn); | |
3277 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 3278 | return ret; |
099fca32 LZ |
3279 | } |
3280 | ||
49957f8e TH |
3281 | /* set uid and gid of cgroup dirs and files to that of the creator */ |
3282 | static int cgroup_kn_set_ugid(struct kernfs_node *kn) | |
3283 | { | |
3284 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, | |
3285 | .ia_uid = current_fsuid(), | |
3286 | .ia_gid = current_fsgid(), }; | |
3287 | ||
3288 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && | |
3289 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) | |
3290 | return 0; | |
3291 | ||
3292 | return kernfs_setattr(kn, &iattr); | |
3293 | } | |
3294 | ||
4df8dc90 TH |
3295 | static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, |
3296 | struct cftype *cft) | |
ddbcc7e8 | 3297 | { |
8d7e6fb0 | 3298 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
3299 | struct kernfs_node *kn; |
3300 | struct lock_class_key *key = NULL; | |
49957f8e | 3301 | int ret; |
05ef1d7c | 3302 | |
2bd59d48 TH |
3303 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
3304 | key = &cft->lockdep_key; | |
3305 | #endif | |
3306 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
3307 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
dfeb0750 | 3308 | NULL, key); |
49957f8e TH |
3309 | if (IS_ERR(kn)) |
3310 | return PTR_ERR(kn); | |
3311 | ||
3312 | ret = cgroup_kn_set_ugid(kn); | |
f8f22e53 | 3313 | if (ret) { |
49957f8e | 3314 | kernfs_remove(kn); |
f8f22e53 TH |
3315 | return ret; |
3316 | } | |
3317 | ||
6f60eade TH |
3318 | if (cft->file_offset) { |
3319 | struct cgroup_file *cfile = (void *)css + cft->file_offset; | |
3320 | ||
3321 | kernfs_get(kn); | |
3322 | cfile->kn = kn; | |
3323 | list_add(&cfile->node, &css->files); | |
3324 | } | |
3325 | ||
f8f22e53 | 3326 | return 0; |
ddbcc7e8 PM |
3327 | } |
3328 | ||
b1f28d31 TH |
3329 | /** |
3330 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
4df8dc90 TH |
3331 | * @css: the target css |
3332 | * @cgrp: the target cgroup (usually css->cgroup) | |
b1f28d31 TH |
3333 | * @cfts: array of cftypes to be added |
3334 | * @is_add: whether to add or remove | |
3335 | * | |
3336 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
6732ed85 | 3337 | * For removals, this function never fails. |
b1f28d31 | 3338 | */ |
4df8dc90 TH |
3339 | static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
3340 | struct cgroup *cgrp, struct cftype cfts[], | |
2bb566cb | 3341 | bool is_add) |
ddbcc7e8 | 3342 | { |
6732ed85 | 3343 | struct cftype *cft, *cft_end = NULL; |
b1f28d31 TH |
3344 | int ret; |
3345 | ||
01f6474c | 3346 | lockdep_assert_held(&cgroup_mutex); |
db0416b6 | 3347 | |
6732ed85 TH |
3348 | restart: |
3349 | for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 3350 | /* does cft->flags tell us to skip this file on @cgrp? */ |
05ebb6e6 | 3351 | if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
8cbbf2c9 | 3352 | continue; |
05ebb6e6 | 3353 | if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
873fe09e | 3354 | continue; |
d51f39b0 | 3355 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
f33fddc2 | 3356 | continue; |
d51f39b0 | 3357 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
f33fddc2 G |
3358 | continue; |
3359 | ||
2739d3cc | 3360 | if (is_add) { |
4df8dc90 | 3361 | ret = cgroup_add_file(css, cgrp, cft); |
b1f28d31 | 3362 | if (ret) { |
ed3d261b JP |
3363 | pr_warn("%s: failed to add %s, err=%d\n", |
3364 | __func__, cft->name, ret); | |
6732ed85 TH |
3365 | cft_end = cft; |
3366 | is_add = false; | |
3367 | goto restart; | |
b1f28d31 | 3368 | } |
2739d3cc LZ |
3369 | } else { |
3370 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 3371 | } |
ddbcc7e8 | 3372 | } |
b1f28d31 | 3373 | return 0; |
ddbcc7e8 PM |
3374 | } |
3375 | ||
21a2d343 | 3376 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
3377 | { |
3378 | LIST_HEAD(pending); | |
2bb566cb | 3379 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 3380 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 3381 | struct cgroup_subsys_state *css; |
9ccece80 | 3382 | int ret = 0; |
8e3f6541 | 3383 | |
01f6474c | 3384 | lockdep_assert_held(&cgroup_mutex); |
e8c82d20 | 3385 | |
e8c82d20 | 3386 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 3387 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
3388 | struct cgroup *cgrp = css->cgroup; |
3389 | ||
e8c82d20 LZ |
3390 | if (cgroup_is_dead(cgrp)) |
3391 | continue; | |
3392 | ||
4df8dc90 | 3393 | ret = cgroup_addrm_files(css, cgrp, cfts, is_add); |
9ccece80 TH |
3394 | if (ret) |
3395 | break; | |
8e3f6541 | 3396 | } |
21a2d343 TH |
3397 | |
3398 | if (is_add && !ret) | |
3399 | kernfs_activate(root->kn); | |
9ccece80 | 3400 | return ret; |
8e3f6541 TH |
3401 | } |
3402 | ||
2da440a2 | 3403 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 3404 | { |
2bb566cb | 3405 | struct cftype *cft; |
8e3f6541 | 3406 | |
2bd59d48 TH |
3407 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3408 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
3409 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
3410 | kfree(cft->kf_ops); | |
3411 | cft->kf_ops = NULL; | |
2da440a2 | 3412 | cft->ss = NULL; |
a8ddc821 TH |
3413 | |
3414 | /* revert flags set by cgroup core while adding @cfts */ | |
05ebb6e6 | 3415 | cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
2bd59d48 | 3416 | } |
2da440a2 TH |
3417 | } |
3418 | ||
2bd59d48 | 3419 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
3420 | { |
3421 | struct cftype *cft; | |
3422 | ||
2bd59d48 TH |
3423 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3424 | struct kernfs_ops *kf_ops; | |
3425 | ||
0adb0704 TH |
3426 | WARN_ON(cft->ss || cft->kf_ops); |
3427 | ||
2bd59d48 TH |
3428 | if (cft->seq_start) |
3429 | kf_ops = &cgroup_kf_ops; | |
3430 | else | |
3431 | kf_ops = &cgroup_kf_single_ops; | |
3432 | ||
3433 | /* | |
3434 | * Ugh... if @cft wants a custom max_write_len, we need to | |
3435 | * make a copy of kf_ops to set its atomic_write_len. | |
3436 | */ | |
3437 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
3438 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
3439 | if (!kf_ops) { | |
3440 | cgroup_exit_cftypes(cfts); | |
3441 | return -ENOMEM; | |
3442 | } | |
3443 | kf_ops->atomic_write_len = cft->max_write_len; | |
3444 | } | |
8e3f6541 | 3445 | |
2bd59d48 | 3446 | cft->kf_ops = kf_ops; |
2bb566cb | 3447 | cft->ss = ss; |
2bd59d48 | 3448 | } |
2bb566cb | 3449 | |
2bd59d48 | 3450 | return 0; |
2da440a2 TH |
3451 | } |
3452 | ||
21a2d343 TH |
3453 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
3454 | { | |
01f6474c | 3455 | lockdep_assert_held(&cgroup_mutex); |
21a2d343 TH |
3456 | |
3457 | if (!cfts || !cfts[0].ss) | |
3458 | return -ENOENT; | |
3459 | ||
3460 | list_del(&cfts->node); | |
3461 | cgroup_apply_cftypes(cfts, false); | |
3462 | cgroup_exit_cftypes(cfts); | |
3463 | return 0; | |
8e3f6541 | 3464 | } |
8e3f6541 | 3465 | |
79578621 TH |
3466 | /** |
3467 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
3468 | * @cfts: zero-length name terminated array of cftypes |
3469 | * | |
2bb566cb TH |
3470 | * Unregister @cfts. Files described by @cfts are removed from all |
3471 | * existing cgroups and all future cgroups won't have them either. This | |
3472 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
3473 | * |
3474 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 3475 | * registered. |
79578621 | 3476 | */ |
2bb566cb | 3477 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 3478 | { |
21a2d343 | 3479 | int ret; |
79578621 | 3480 | |
01f6474c | 3481 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3482 | ret = cgroup_rm_cftypes_locked(cfts); |
01f6474c | 3483 | mutex_unlock(&cgroup_mutex); |
21a2d343 | 3484 | return ret; |
80b13586 TH |
3485 | } |
3486 | ||
8e3f6541 TH |
3487 | /** |
3488 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
3489 | * @ss: target cgroup subsystem | |
3490 | * @cfts: zero-length name terminated array of cftypes | |
3491 | * | |
3492 | * Register @cfts to @ss. Files described by @cfts are created for all | |
3493 | * existing cgroups to which @ss is attached and all future cgroups will | |
3494 | * have them too. This function can be called anytime whether @ss is | |
3495 | * attached or not. | |
3496 | * | |
3497 | * Returns 0 on successful registration, -errno on failure. Note that this | |
3498 | * function currently returns 0 as long as @cfts registration is successful | |
3499 | * even if some file creation attempts on existing cgroups fail. | |
3500 | */ | |
2cf669a5 | 3501 | static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 3502 | { |
9ccece80 | 3503 | int ret; |
8e3f6541 | 3504 | |
fc5ed1e9 | 3505 | if (!cgroup_ssid_enabled(ss->id)) |
c731ae1d LZ |
3506 | return 0; |
3507 | ||
dc5736ed LZ |
3508 | if (!cfts || cfts[0].name[0] == '\0') |
3509 | return 0; | |
2bb566cb | 3510 | |
2bd59d48 TH |
3511 | ret = cgroup_init_cftypes(ss, cfts); |
3512 | if (ret) | |
3513 | return ret; | |
79578621 | 3514 | |
01f6474c | 3515 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3516 | |
0adb0704 | 3517 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 3518 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 3519 | if (ret) |
21a2d343 | 3520 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 3521 | |
01f6474c | 3522 | mutex_unlock(&cgroup_mutex); |
9ccece80 | 3523 | return ret; |
79578621 TH |
3524 | } |
3525 | ||
a8ddc821 TH |
3526 | /** |
3527 | * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy | |
3528 | * @ss: target cgroup subsystem | |
3529 | * @cfts: zero-length name terminated array of cftypes | |
3530 | * | |
3531 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3532 | * the default hierarchy. | |
3533 | */ | |
3534 | int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
3535 | { | |
3536 | struct cftype *cft; | |
3537 | ||
3538 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
05ebb6e6 | 3539 | cft->flags |= __CFTYPE_ONLY_ON_DFL; |
a8ddc821 TH |
3540 | return cgroup_add_cftypes(ss, cfts); |
3541 | } | |
3542 | ||
3543 | /** | |
3544 | * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies | |
3545 | * @ss: target cgroup subsystem | |
3546 | * @cfts: zero-length name terminated array of cftypes | |
3547 | * | |
3548 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3549 | * the legacy hierarchies. | |
3550 | */ | |
2cf669a5 TH |
3551 | int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
3552 | { | |
a8ddc821 TH |
3553 | struct cftype *cft; |
3554 | ||
fa8137be VG |
3555 | /* |
3556 | * If legacy_flies_on_dfl, we want to show the legacy files on the | |
3557 | * dfl hierarchy but iff the target subsystem hasn't been updated | |
3558 | * for the dfl hierarchy yet. | |
3559 | */ | |
3560 | if (!cgroup_legacy_files_on_dfl || | |
3561 | ss->dfl_cftypes != ss->legacy_cftypes) { | |
3562 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
3563 | cft->flags |= __CFTYPE_NOT_ON_DFL; | |
3564 | } | |
3565 | ||
2cf669a5 TH |
3566 | return cgroup_add_cftypes(ss, cfts); |
3567 | } | |
3568 | ||
a043e3b2 LZ |
3569 | /** |
3570 | * cgroup_task_count - count the number of tasks in a cgroup. | |
3571 | * @cgrp: the cgroup in question | |
3572 | * | |
3573 | * Return the number of tasks in the cgroup. | |
3574 | */ | |
07bc356e | 3575 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
3576 | { |
3577 | int count = 0; | |
69d0206c | 3578 | struct cgrp_cset_link *link; |
817929ec | 3579 | |
f0d9a5f1 | 3580 | spin_lock_bh(&css_set_lock); |
69d0206c TH |
3581 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
3582 | count += atomic_read(&link->cset->refcount); | |
f0d9a5f1 | 3583 | spin_unlock_bh(&css_set_lock); |
bbcb81d0 PM |
3584 | return count; |
3585 | } | |
3586 | ||
53fa5261 | 3587 | /** |
492eb21b | 3588 | * css_next_child - find the next child of a given css |
c2931b70 TH |
3589 | * @pos: the current position (%NULL to initiate traversal) |
3590 | * @parent: css whose children to walk | |
53fa5261 | 3591 | * |
c2931b70 | 3592 | * This function returns the next child of @parent and should be called |
87fb54f1 | 3593 | * under either cgroup_mutex or RCU read lock. The only requirement is |
c2931b70 TH |
3594 | * that @parent and @pos are accessible. The next sibling is guaranteed to |
3595 | * be returned regardless of their states. | |
3596 | * | |
3597 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3598 | * css which finished ->css_online() is guaranteed to be visible in the | |
3599 | * future iterations and will stay visible until the last reference is put. | |
3600 | * A css which hasn't finished ->css_online() or already finished | |
3601 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3602 | * responsibility to synchronize against on/offlining. | |
53fa5261 | 3603 | */ |
c2931b70 TH |
3604 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
3605 | struct cgroup_subsys_state *parent) | |
53fa5261 | 3606 | { |
c2931b70 | 3607 | struct cgroup_subsys_state *next; |
53fa5261 | 3608 | |
8353da1f | 3609 | cgroup_assert_mutex_or_rcu_locked(); |
53fa5261 TH |
3610 | |
3611 | /* | |
de3f0341 TH |
3612 | * @pos could already have been unlinked from the sibling list. |
3613 | * Once a cgroup is removed, its ->sibling.next is no longer | |
3614 | * updated when its next sibling changes. CSS_RELEASED is set when | |
3615 | * @pos is taken off list, at which time its next pointer is valid, | |
3616 | * and, as releases are serialized, the one pointed to by the next | |
3617 | * pointer is guaranteed to not have started release yet. This | |
3618 | * implies that if we observe !CSS_RELEASED on @pos in this RCU | |
3619 | * critical section, the one pointed to by its next pointer is | |
3620 | * guaranteed to not have finished its RCU grace period even if we | |
3621 | * have dropped rcu_read_lock() inbetween iterations. | |
3b287a50 | 3622 | * |
de3f0341 TH |
3623 | * If @pos has CSS_RELEASED set, its next pointer can't be |
3624 | * dereferenced; however, as each css is given a monotonically | |
3625 | * increasing unique serial number and always appended to the | |
3626 | * sibling list, the next one can be found by walking the parent's | |
3627 | * children until the first css with higher serial number than | |
3628 | * @pos's. While this path can be slower, it happens iff iteration | |
3629 | * races against release and the race window is very small. | |
53fa5261 | 3630 | */ |
3b287a50 | 3631 | if (!pos) { |
c2931b70 TH |
3632 | next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
3633 | } else if (likely(!(pos->flags & CSS_RELEASED))) { | |
3634 | next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); | |
3b287a50 | 3635 | } else { |
c2931b70 | 3636 | list_for_each_entry_rcu(next, &parent->children, sibling) |
3b287a50 TH |
3637 | if (next->serial_nr > pos->serial_nr) |
3638 | break; | |
53fa5261 TH |
3639 | } |
3640 | ||
3b281afb TH |
3641 | /* |
3642 | * @next, if not pointing to the head, can be dereferenced and is | |
c2931b70 | 3643 | * the next sibling. |
3b281afb | 3644 | */ |
c2931b70 TH |
3645 | if (&next->sibling != &parent->children) |
3646 | return next; | |
3b281afb | 3647 | return NULL; |
53fa5261 | 3648 | } |
53fa5261 | 3649 | |
574bd9f7 | 3650 | /** |
492eb21b | 3651 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 3652 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3653 | * @root: css whose descendants to walk |
574bd9f7 | 3654 | * |
492eb21b | 3655 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
3656 | * to visit for pre-order traversal of @root's descendants. @root is |
3657 | * included in the iteration and the first node to be visited. | |
75501a6d | 3658 | * |
87fb54f1 TH |
3659 | * While this function requires cgroup_mutex or RCU read locking, it |
3660 | * doesn't require the whole traversal to be contained in a single critical | |
3661 | * section. This function will return the correct next descendant as long | |
3662 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
c2931b70 TH |
3663 | * |
3664 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3665 | * css which finished ->css_online() is guaranteed to be visible in the | |
3666 | * future iterations and will stay visible until the last reference is put. | |
3667 | * A css which hasn't finished ->css_online() or already finished | |
3668 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3669 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3670 | */ |
492eb21b TH |
3671 | struct cgroup_subsys_state * |
3672 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
3673 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3674 | { |
492eb21b | 3675 | struct cgroup_subsys_state *next; |
574bd9f7 | 3676 | |
8353da1f | 3677 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3678 | |
bd8815a6 | 3679 | /* if first iteration, visit @root */ |
7805d000 | 3680 | if (!pos) |
bd8815a6 | 3681 | return root; |
574bd9f7 TH |
3682 | |
3683 | /* visit the first child if exists */ | |
492eb21b | 3684 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
3685 | if (next) |
3686 | return next; | |
3687 | ||
3688 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b | 3689 | while (pos != root) { |
5c9d535b | 3690 | next = css_next_child(pos, pos->parent); |
75501a6d | 3691 | if (next) |
574bd9f7 | 3692 | return next; |
5c9d535b | 3693 | pos = pos->parent; |
7805d000 | 3694 | } |
574bd9f7 TH |
3695 | |
3696 | return NULL; | |
3697 | } | |
574bd9f7 | 3698 | |
12a9d2fe | 3699 | /** |
492eb21b TH |
3700 | * css_rightmost_descendant - return the rightmost descendant of a css |
3701 | * @pos: css of interest | |
12a9d2fe | 3702 | * |
492eb21b TH |
3703 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
3704 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 3705 | * subtree of @pos. |
75501a6d | 3706 | * |
87fb54f1 TH |
3707 | * While this function requires cgroup_mutex or RCU read locking, it |
3708 | * doesn't require the whole traversal to be contained in a single critical | |
3709 | * section. This function will return the correct rightmost descendant as | |
3710 | * long as @pos is accessible. | |
12a9d2fe | 3711 | */ |
492eb21b TH |
3712 | struct cgroup_subsys_state * |
3713 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 3714 | { |
492eb21b | 3715 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 3716 | |
8353da1f | 3717 | cgroup_assert_mutex_or_rcu_locked(); |
12a9d2fe TH |
3718 | |
3719 | do { | |
3720 | last = pos; | |
3721 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3722 | pos = NULL; | |
492eb21b | 3723 | css_for_each_child(tmp, last) |
12a9d2fe TH |
3724 | pos = tmp; |
3725 | } while (pos); | |
3726 | ||
3727 | return last; | |
3728 | } | |
12a9d2fe | 3729 | |
492eb21b TH |
3730 | static struct cgroup_subsys_state * |
3731 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 3732 | { |
492eb21b | 3733 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
3734 | |
3735 | do { | |
3736 | last = pos; | |
492eb21b | 3737 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
3738 | } while (pos); |
3739 | ||
3740 | return last; | |
3741 | } | |
3742 | ||
3743 | /** | |
492eb21b | 3744 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 3745 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3746 | * @root: css whose descendants to walk |
574bd9f7 | 3747 | * |
492eb21b | 3748 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
3749 | * to visit for post-order traversal of @root's descendants. @root is |
3750 | * included in the iteration and the last node to be visited. | |
75501a6d | 3751 | * |
87fb54f1 TH |
3752 | * While this function requires cgroup_mutex or RCU read locking, it |
3753 | * doesn't require the whole traversal to be contained in a single critical | |
3754 | * section. This function will return the correct next descendant as long | |
3755 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
3756 | * @cgroup. | |
c2931b70 TH |
3757 | * |
3758 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3759 | * css which finished ->css_online() is guaranteed to be visible in the | |
3760 | * future iterations and will stay visible until the last reference is put. | |
3761 | * A css which hasn't finished ->css_online() or already finished | |
3762 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3763 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3764 | */ |
492eb21b TH |
3765 | struct cgroup_subsys_state * |
3766 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
3767 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3768 | { |
492eb21b | 3769 | struct cgroup_subsys_state *next; |
574bd9f7 | 3770 | |
8353da1f | 3771 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3772 | |
58b79a91 TH |
3773 | /* if first iteration, visit leftmost descendant which may be @root */ |
3774 | if (!pos) | |
3775 | return css_leftmost_descendant(root); | |
574bd9f7 | 3776 | |
bd8815a6 TH |
3777 | /* if we visited @root, we're done */ |
3778 | if (pos == root) | |
3779 | return NULL; | |
3780 | ||
574bd9f7 | 3781 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
5c9d535b | 3782 | next = css_next_child(pos, pos->parent); |
75501a6d | 3783 | if (next) |
492eb21b | 3784 | return css_leftmost_descendant(next); |
574bd9f7 TH |
3785 | |
3786 | /* no sibling left, visit parent */ | |
5c9d535b | 3787 | return pos->parent; |
574bd9f7 | 3788 | } |
574bd9f7 | 3789 | |
f3d46500 TH |
3790 | /** |
3791 | * css_has_online_children - does a css have online children | |
3792 | * @css: the target css | |
3793 | * | |
3794 | * Returns %true if @css has any online children; otherwise, %false. This | |
3795 | * function can be called from any context but the caller is responsible | |
3796 | * for synchronizing against on/offlining as necessary. | |
3797 | */ | |
3798 | bool css_has_online_children(struct cgroup_subsys_state *css) | |
cbc125ef | 3799 | { |
f3d46500 TH |
3800 | struct cgroup_subsys_state *child; |
3801 | bool ret = false; | |
cbc125ef TH |
3802 | |
3803 | rcu_read_lock(); | |
f3d46500 | 3804 | css_for_each_child(child, css) { |
99bae5f9 | 3805 | if (child->flags & CSS_ONLINE) { |
f3d46500 TH |
3806 | ret = true; |
3807 | break; | |
cbc125ef TH |
3808 | } |
3809 | } | |
3810 | rcu_read_unlock(); | |
f3d46500 | 3811 | return ret; |
574bd9f7 | 3812 | } |
574bd9f7 | 3813 | |
0942eeee | 3814 | /** |
ecb9d535 | 3815 | * css_task_iter_advance_css_set - advance a task itererator to the next css_set |
0942eeee TH |
3816 | * @it: the iterator to advance |
3817 | * | |
3818 | * Advance @it to the next css_set to walk. | |
d515876e | 3819 | */ |
ecb9d535 | 3820 | static void css_task_iter_advance_css_set(struct css_task_iter *it) |
d515876e | 3821 | { |
0f0a2b4f | 3822 | struct list_head *l = it->cset_pos; |
d515876e TH |
3823 | struct cgrp_cset_link *link; |
3824 | struct css_set *cset; | |
3825 | ||
f0d9a5f1 | 3826 | lockdep_assert_held(&css_set_lock); |
ed27b9f7 | 3827 | |
d515876e TH |
3828 | /* Advance to the next non-empty css_set */ |
3829 | do { | |
3830 | l = l->next; | |
0f0a2b4f TH |
3831 | if (l == it->cset_head) { |
3832 | it->cset_pos = NULL; | |
ecb9d535 | 3833 | it->task_pos = NULL; |
d515876e TH |
3834 | return; |
3835 | } | |
3ebb2b6e TH |
3836 | |
3837 | if (it->ss) { | |
3838 | cset = container_of(l, struct css_set, | |
3839 | e_cset_node[it->ss->id]); | |
3840 | } else { | |
3841 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
3842 | cset = link->cset; | |
3843 | } | |
0de0942d | 3844 | } while (!css_set_populated(cset)); |
c7561128 | 3845 | |
0f0a2b4f | 3846 | it->cset_pos = l; |
c7561128 TH |
3847 | |
3848 | if (!list_empty(&cset->tasks)) | |
0f0a2b4f | 3849 | it->task_pos = cset->tasks.next; |
c7561128 | 3850 | else |
0f0a2b4f TH |
3851 | it->task_pos = cset->mg_tasks.next; |
3852 | ||
3853 | it->tasks_head = &cset->tasks; | |
3854 | it->mg_tasks_head = &cset->mg_tasks; | |
ed27b9f7 TH |
3855 | |
3856 | /* | |
3857 | * We don't keep css_sets locked across iteration steps and thus | |
3858 | * need to take steps to ensure that iteration can be resumed after | |
3859 | * the lock is re-acquired. Iteration is performed at two levels - | |
3860 | * css_sets and tasks in them. | |
3861 | * | |
3862 | * Once created, a css_set never leaves its cgroup lists, so a | |
3863 | * pinned css_set is guaranteed to stay put and we can resume | |
3864 | * iteration afterwards. | |
3865 | * | |
3866 | * Tasks may leave @cset across iteration steps. This is resolved | |
3867 | * by registering each iterator with the css_set currently being | |
3868 | * walked and making css_set_move_task() advance iterators whose | |
3869 | * next task is leaving. | |
3870 | */ | |
3871 | if (it->cur_cset) { | |
3872 | list_del(&it->iters_node); | |
3873 | put_css_set_locked(it->cur_cset); | |
3874 | } | |
3875 | get_css_set(cset); | |
3876 | it->cur_cset = cset; | |
3877 | list_add(&it->iters_node, &cset->task_iters); | |
d515876e TH |
3878 | } |
3879 | ||
ecb9d535 TH |
3880 | static void css_task_iter_advance(struct css_task_iter *it) |
3881 | { | |
3882 | struct list_head *l = it->task_pos; | |
3883 | ||
f0d9a5f1 | 3884 | lockdep_assert_held(&css_set_lock); |
ecb9d535 TH |
3885 | WARN_ON_ONCE(!l); |
3886 | ||
3887 | /* | |
3888 | * Advance iterator to find next entry. cset->tasks is consumed | |
3889 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
3890 | * next cset. | |
3891 | */ | |
3892 | l = l->next; | |
3893 | ||
3894 | if (l == it->tasks_head) | |
3895 | l = it->mg_tasks_head->next; | |
3896 | ||
3897 | if (l == it->mg_tasks_head) | |
3898 | css_task_iter_advance_css_set(it); | |
3899 | else | |
3900 | it->task_pos = l; | |
3901 | } | |
3902 | ||
0942eeee | 3903 | /** |
72ec7029 TH |
3904 | * css_task_iter_start - initiate task iteration |
3905 | * @css: the css to walk tasks of | |
0942eeee TH |
3906 | * @it: the task iterator to use |
3907 | * | |
72ec7029 TH |
3908 | * Initiate iteration through the tasks of @css. The caller can call |
3909 | * css_task_iter_next() to walk through the tasks until the function | |
3910 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
3911 | * called. | |
0942eeee | 3912 | */ |
72ec7029 TH |
3913 | void css_task_iter_start(struct cgroup_subsys_state *css, |
3914 | struct css_task_iter *it) | |
817929ec | 3915 | { |
56fde9e0 TH |
3916 | /* no one should try to iterate before mounting cgroups */ |
3917 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 3918 | |
ed27b9f7 TH |
3919 | memset(it, 0, sizeof(*it)); |
3920 | ||
f0d9a5f1 | 3921 | spin_lock_bh(&css_set_lock); |
c59cd3d8 | 3922 | |
3ebb2b6e TH |
3923 | it->ss = css->ss; |
3924 | ||
3925 | if (it->ss) | |
3926 | it->cset_pos = &css->cgroup->e_csets[css->ss->id]; | |
3927 | else | |
3928 | it->cset_pos = &css->cgroup->cset_links; | |
3929 | ||
0f0a2b4f | 3930 | it->cset_head = it->cset_pos; |
c59cd3d8 | 3931 | |
ecb9d535 | 3932 | css_task_iter_advance_css_set(it); |
ed27b9f7 | 3933 | |
f0d9a5f1 | 3934 | spin_unlock_bh(&css_set_lock); |
817929ec PM |
3935 | } |
3936 | ||
0942eeee | 3937 | /** |
72ec7029 | 3938 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
3939 | * @it: the task iterator being iterated |
3940 | * | |
3941 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
3942 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
3943 | * reaches the end. | |
0942eeee | 3944 | */ |
72ec7029 | 3945 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec | 3946 | { |
0f0a2b4f | 3947 | if (!it->cset_pos) |
817929ec | 3948 | return NULL; |
c7561128 | 3949 | |
ed27b9f7 TH |
3950 | if (it->cur_task) |
3951 | put_task_struct(it->cur_task); | |
3952 | ||
f0d9a5f1 | 3953 | spin_lock_bh(&css_set_lock); |
ed27b9f7 TH |
3954 | |
3955 | it->cur_task = list_entry(it->task_pos, struct task_struct, cg_list); | |
3956 | get_task_struct(it->cur_task); | |
3957 | ||
ecb9d535 | 3958 | css_task_iter_advance(it); |
ed27b9f7 | 3959 | |
f0d9a5f1 | 3960 | spin_unlock_bh(&css_set_lock); |
ed27b9f7 TH |
3961 | |
3962 | return it->cur_task; | |
817929ec PM |
3963 | } |
3964 | ||
0942eeee | 3965 | /** |
72ec7029 | 3966 | * css_task_iter_end - finish task iteration |
0942eeee TH |
3967 | * @it: the task iterator to finish |
3968 | * | |
72ec7029 | 3969 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 3970 | */ |
72ec7029 | 3971 | void css_task_iter_end(struct css_task_iter *it) |
31a7df01 | 3972 | { |
ed27b9f7 | 3973 | if (it->cur_cset) { |
f0d9a5f1 | 3974 | spin_lock_bh(&css_set_lock); |
ed27b9f7 TH |
3975 | list_del(&it->iters_node); |
3976 | put_css_set_locked(it->cur_cset); | |
f0d9a5f1 | 3977 | spin_unlock_bh(&css_set_lock); |
ed27b9f7 TH |
3978 | } |
3979 | ||
3980 | if (it->cur_task) | |
3981 | put_task_struct(it->cur_task); | |
31a7df01 CW |
3982 | } |
3983 | ||
3984 | /** | |
8cc99345 TH |
3985 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
3986 | * @to: cgroup to which the tasks will be moved | |
3987 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 3988 | * |
eaf797ab TH |
3989 | * Locking rules between cgroup_post_fork() and the migration path |
3990 | * guarantee that, if a task is forking while being migrated, the new child | |
3991 | * is guaranteed to be either visible in the source cgroup after the | |
3992 | * parent's migration is complete or put into the target cgroup. No task | |
3993 | * can slip out of migration through forking. | |
31a7df01 | 3994 | */ |
8cc99345 | 3995 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 3996 | { |
952aaa12 TH |
3997 | LIST_HEAD(preloaded_csets); |
3998 | struct cgrp_cset_link *link; | |
72ec7029 | 3999 | struct css_task_iter it; |
e406d1cf | 4000 | struct task_struct *task; |
952aaa12 | 4001 | int ret; |
31a7df01 | 4002 | |
952aaa12 | 4003 | mutex_lock(&cgroup_mutex); |
31a7df01 | 4004 | |
952aaa12 | 4005 | /* all tasks in @from are being moved, all csets are source */ |
f0d9a5f1 | 4006 | spin_lock_bh(&css_set_lock); |
952aaa12 TH |
4007 | list_for_each_entry(link, &from->cset_links, cset_link) |
4008 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
f0d9a5f1 | 4009 | spin_unlock_bh(&css_set_lock); |
31a7df01 | 4010 | |
952aaa12 TH |
4011 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
4012 | if (ret) | |
4013 | goto out_err; | |
8cc99345 | 4014 | |
952aaa12 TH |
4015 | /* |
4016 | * Migrate tasks one-by-one until @form is empty. This fails iff | |
4017 | * ->can_attach() fails. | |
4018 | */ | |
e406d1cf | 4019 | do { |
9d800df1 | 4020 | css_task_iter_start(&from->self, &it); |
e406d1cf TH |
4021 | task = css_task_iter_next(&it); |
4022 | if (task) | |
4023 | get_task_struct(task); | |
4024 | css_task_iter_end(&it); | |
4025 | ||
4026 | if (task) { | |
9af2ec45 | 4027 | ret = cgroup_migrate(task, false, to); |
e406d1cf TH |
4028 | put_task_struct(task); |
4029 | } | |
4030 | } while (task && !ret); | |
952aaa12 TH |
4031 | out_err: |
4032 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 4033 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 4034 | return ret; |
8cc99345 TH |
4035 | } |
4036 | ||
bbcb81d0 | 4037 | /* |
102a775e | 4038 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
4039 | * |
4040 | * Reading this file can return large amounts of data if a cgroup has | |
4041 | * *lots* of attached tasks. So it may need several calls to read(), | |
4042 | * but we cannot guarantee that the information we produce is correct | |
4043 | * unless we produce it entirely atomically. | |
4044 | * | |
bbcb81d0 | 4045 | */ |
bbcb81d0 | 4046 | |
24528255 LZ |
4047 | /* which pidlist file are we talking about? */ |
4048 | enum cgroup_filetype { | |
4049 | CGROUP_FILE_PROCS, | |
4050 | CGROUP_FILE_TASKS, | |
4051 | }; | |
4052 | ||
4053 | /* | |
4054 | * A pidlist is a list of pids that virtually represents the contents of one | |
4055 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
4056 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
4057 | * to the cgroup. | |
4058 | */ | |
4059 | struct cgroup_pidlist { | |
4060 | /* | |
4061 | * used to find which pidlist is wanted. doesn't change as long as | |
4062 | * this particular list stays in the list. | |
4063 | */ | |
4064 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
4065 | /* array of xids */ | |
4066 | pid_t *list; | |
4067 | /* how many elements the above list has */ | |
4068 | int length; | |
24528255 LZ |
4069 | /* each of these stored in a list by its cgroup */ |
4070 | struct list_head links; | |
4071 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
4072 | struct cgroup *owner; | |
b1a21367 TH |
4073 | /* for delayed destruction */ |
4074 | struct delayed_work destroy_dwork; | |
24528255 LZ |
4075 | }; |
4076 | ||
d1d9fd33 BB |
4077 | /* |
4078 | * The following two functions "fix" the issue where there are more pids | |
4079 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
4080 | * TODO: replace with a kernel-wide solution to this problem | |
4081 | */ | |
4082 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
4083 | static void *pidlist_allocate(int count) | |
4084 | { | |
4085 | if (PIDLIST_TOO_LARGE(count)) | |
4086 | return vmalloc(count * sizeof(pid_t)); | |
4087 | else | |
4088 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
4089 | } | |
b1a21367 | 4090 | |
d1d9fd33 BB |
4091 | static void pidlist_free(void *p) |
4092 | { | |
58794514 | 4093 | kvfree(p); |
d1d9fd33 | 4094 | } |
d1d9fd33 | 4095 | |
b1a21367 TH |
4096 | /* |
4097 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
4098 | * should be left afterwards. | |
4099 | */ | |
4100 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
4101 | { | |
4102 | struct cgroup_pidlist *l, *tmp_l; | |
4103 | ||
4104 | mutex_lock(&cgrp->pidlist_mutex); | |
4105 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
4106 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
4107 | mutex_unlock(&cgrp->pidlist_mutex); | |
4108 | ||
4109 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
4110 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
4111 | } | |
4112 | ||
4113 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
4114 | { | |
4115 | struct delayed_work *dwork = to_delayed_work(work); | |
4116 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
4117 | destroy_dwork); | |
4118 | struct cgroup_pidlist *tofree = NULL; | |
4119 | ||
4120 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
4121 | |
4122 | /* | |
04502365 TH |
4123 | * Destroy iff we didn't get queued again. The state won't change |
4124 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 4125 | */ |
04502365 | 4126 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
4127 | list_del(&l->links); |
4128 | pidlist_free(l->list); | |
4129 | put_pid_ns(l->key.ns); | |
4130 | tofree = l; | |
4131 | } | |
4132 | ||
b1a21367 TH |
4133 | mutex_unlock(&l->owner->pidlist_mutex); |
4134 | kfree(tofree); | |
4135 | } | |
4136 | ||
bbcb81d0 | 4137 | /* |
102a775e | 4138 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 4139 | * Returns the number of unique elements. |
bbcb81d0 | 4140 | */ |
6ee211ad | 4141 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 4142 | { |
102a775e | 4143 | int src, dest = 1; |
102a775e BB |
4144 | |
4145 | /* | |
4146 | * we presume the 0th element is unique, so i starts at 1. trivial | |
4147 | * edge cases first; no work needs to be done for either | |
4148 | */ | |
4149 | if (length == 0 || length == 1) | |
4150 | return length; | |
4151 | /* src and dest walk down the list; dest counts unique elements */ | |
4152 | for (src = 1; src < length; src++) { | |
4153 | /* find next unique element */ | |
4154 | while (list[src] == list[src-1]) { | |
4155 | src++; | |
4156 | if (src == length) | |
4157 | goto after; | |
4158 | } | |
4159 | /* dest always points to where the next unique element goes */ | |
4160 | list[dest] = list[src]; | |
4161 | dest++; | |
4162 | } | |
4163 | after: | |
102a775e BB |
4164 | return dest; |
4165 | } | |
4166 | ||
afb2bc14 TH |
4167 | /* |
4168 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
4169 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
4170 | * different per namespace, each namespace needs differently sorted list, | |
4171 | * making it impossible to use, for example, single rbtree of member tasks | |
4172 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
4173 | * per open file is dangerous, so cgroup had to implement shared pool of | |
4174 | * pidlists keyed by cgroup and namespace. | |
4175 | * | |
4176 | * All this extra complexity was caused by the original implementation | |
4177 | * committing to an entirely unnecessary property. In the long term, we | |
aa6ec29b TH |
4178 | * want to do away with it. Explicitly scramble sort order if on the |
4179 | * default hierarchy so that no such expectation exists in the new | |
4180 | * interface. | |
afb2bc14 TH |
4181 | * |
4182 | * Scrambling is done by swapping every two consecutive bits, which is | |
4183 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
4184 | */ | |
4185 | static pid_t pid_fry(pid_t pid) | |
4186 | { | |
4187 | unsigned a = pid & 0x55555555; | |
4188 | unsigned b = pid & 0xAAAAAAAA; | |
4189 | ||
4190 | return (a << 1) | (b >> 1); | |
4191 | } | |
4192 | ||
4193 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
4194 | { | |
aa6ec29b | 4195 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4196 | return pid_fry(pid); |
4197 | else | |
4198 | return pid; | |
4199 | } | |
4200 | ||
102a775e BB |
4201 | static int cmppid(const void *a, const void *b) |
4202 | { | |
4203 | return *(pid_t *)a - *(pid_t *)b; | |
4204 | } | |
4205 | ||
afb2bc14 TH |
4206 | static int fried_cmppid(const void *a, const void *b) |
4207 | { | |
4208 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
4209 | } | |
4210 | ||
e6b81710 TH |
4211 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
4212 | enum cgroup_filetype type) | |
4213 | { | |
4214 | struct cgroup_pidlist *l; | |
4215 | /* don't need task_nsproxy() if we're looking at ourself */ | |
4216 | struct pid_namespace *ns = task_active_pid_ns(current); | |
4217 | ||
4218 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
4219 | ||
4220 | list_for_each_entry(l, &cgrp->pidlists, links) | |
4221 | if (l->key.type == type && l->key.ns == ns) | |
4222 | return l; | |
4223 | return NULL; | |
4224 | } | |
4225 | ||
72a8cb30 BB |
4226 | /* |
4227 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
4228 | * returns with the lock on that pidlist already held, and takes care | |
4229 | * of the use count, or returns NULL with no locks held if we're out of | |
4230 | * memory. | |
4231 | */ | |
e6b81710 TH |
4232 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
4233 | enum cgroup_filetype type) | |
72a8cb30 BB |
4234 | { |
4235 | struct cgroup_pidlist *l; | |
b70cc5fd | 4236 | |
e6b81710 TH |
4237 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4238 | ||
4239 | l = cgroup_pidlist_find(cgrp, type); | |
4240 | if (l) | |
4241 | return l; | |
4242 | ||
72a8cb30 | 4243 | /* entry not found; create a new one */ |
f4f4be2b | 4244 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 4245 | if (!l) |
72a8cb30 | 4246 | return l; |
e6b81710 | 4247 | |
b1a21367 | 4248 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 4249 | l->key.type = type; |
e6b81710 TH |
4250 | /* don't need task_nsproxy() if we're looking at ourself */ |
4251 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
4252 | l->owner = cgrp; |
4253 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
4254 | return l; |
4255 | } | |
4256 | ||
102a775e BB |
4257 | /* |
4258 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
4259 | */ | |
72a8cb30 BB |
4260 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
4261 | struct cgroup_pidlist **lp) | |
102a775e BB |
4262 | { |
4263 | pid_t *array; | |
4264 | int length; | |
4265 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 4266 | struct css_task_iter it; |
817929ec | 4267 | struct task_struct *tsk; |
102a775e BB |
4268 | struct cgroup_pidlist *l; |
4269 | ||
4bac00d1 TH |
4270 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4271 | ||
102a775e BB |
4272 | /* |
4273 | * If cgroup gets more users after we read count, we won't have | |
4274 | * enough space - tough. This race is indistinguishable to the | |
4275 | * caller from the case that the additional cgroup users didn't | |
4276 | * show up until sometime later on. | |
4277 | */ | |
4278 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 4279 | array = pidlist_allocate(length); |
102a775e BB |
4280 | if (!array) |
4281 | return -ENOMEM; | |
4282 | /* now, populate the array */ | |
9d800df1 | 4283 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4284 | while ((tsk = css_task_iter_next(&it))) { |
102a775e | 4285 | if (unlikely(n == length)) |
817929ec | 4286 | break; |
102a775e | 4287 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
4288 | if (type == CGROUP_FILE_PROCS) |
4289 | pid = task_tgid_vnr(tsk); | |
4290 | else | |
4291 | pid = task_pid_vnr(tsk); | |
102a775e BB |
4292 | if (pid > 0) /* make sure to only use valid results */ |
4293 | array[n++] = pid; | |
817929ec | 4294 | } |
72ec7029 | 4295 | css_task_iter_end(&it); |
102a775e BB |
4296 | length = n; |
4297 | /* now sort & (if procs) strip out duplicates */ | |
aa6ec29b | 4298 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4299 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
4300 | else | |
4301 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 4302 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 4303 | length = pidlist_uniq(array, length); |
e6b81710 | 4304 | |
e6b81710 | 4305 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 4306 | if (!l) { |
d1d9fd33 | 4307 | pidlist_free(array); |
72a8cb30 | 4308 | return -ENOMEM; |
102a775e | 4309 | } |
e6b81710 TH |
4310 | |
4311 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 4312 | pidlist_free(l->list); |
102a775e BB |
4313 | l->list = array; |
4314 | l->length = length; | |
72a8cb30 | 4315 | *lp = l; |
102a775e | 4316 | return 0; |
bbcb81d0 PM |
4317 | } |
4318 | ||
846c7bb0 | 4319 | /** |
a043e3b2 | 4320 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
4321 | * @stats: cgroupstats to fill information into |
4322 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
4323 | * been requested. | |
a043e3b2 LZ |
4324 | * |
4325 | * Build and fill cgroupstats so that taskstats can export it to user | |
4326 | * space. | |
846c7bb0 BS |
4327 | */ |
4328 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
4329 | { | |
2bd59d48 | 4330 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 4331 | struct cgroup *cgrp; |
72ec7029 | 4332 | struct css_task_iter it; |
846c7bb0 | 4333 | struct task_struct *tsk; |
33d283be | 4334 | |
2bd59d48 TH |
4335 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
4336 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
4337 | kernfs_type(kn) != KERNFS_DIR) | |
4338 | return -EINVAL; | |
4339 | ||
bad34660 LZ |
4340 | mutex_lock(&cgroup_mutex); |
4341 | ||
846c7bb0 | 4342 | /* |
2bd59d48 | 4343 | * We aren't being called from kernfs and there's no guarantee on |
ec903c0c | 4344 | * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
2bd59d48 | 4345 | * @kn->priv is RCU safe. Let's do the RCU dancing. |
846c7bb0 | 4346 | */ |
2bd59d48 TH |
4347 | rcu_read_lock(); |
4348 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 4349 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 4350 | rcu_read_unlock(); |
bad34660 | 4351 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
4352 | return -ENOENT; |
4353 | } | |
bad34660 | 4354 | rcu_read_unlock(); |
846c7bb0 | 4355 | |
9d800df1 | 4356 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4357 | while ((tsk = css_task_iter_next(&it))) { |
846c7bb0 BS |
4358 | switch (tsk->state) { |
4359 | case TASK_RUNNING: | |
4360 | stats->nr_running++; | |
4361 | break; | |
4362 | case TASK_INTERRUPTIBLE: | |
4363 | stats->nr_sleeping++; | |
4364 | break; | |
4365 | case TASK_UNINTERRUPTIBLE: | |
4366 | stats->nr_uninterruptible++; | |
4367 | break; | |
4368 | case TASK_STOPPED: | |
4369 | stats->nr_stopped++; | |
4370 | break; | |
4371 | default: | |
4372 | if (delayacct_is_task_waiting_on_io(tsk)) | |
4373 | stats->nr_io_wait++; | |
4374 | break; | |
4375 | } | |
4376 | } | |
72ec7029 | 4377 | css_task_iter_end(&it); |
846c7bb0 | 4378 | |
bad34660 | 4379 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 4380 | return 0; |
846c7bb0 BS |
4381 | } |
4382 | ||
8f3ff208 | 4383 | |
bbcb81d0 | 4384 | /* |
102a775e | 4385 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 4386 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 4387 | * in the cgroup->l->list array. |
bbcb81d0 | 4388 | */ |
cc31edce | 4389 | |
102a775e | 4390 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 4391 | { |
cc31edce PM |
4392 | /* |
4393 | * Initially we receive a position value that corresponds to | |
4394 | * one more than the last pid shown (or 0 on the first call or | |
4395 | * after a seek to the start). Use a binary-search to find the | |
4396 | * next pid to display, if any | |
4397 | */ | |
2bd59d48 | 4398 | struct kernfs_open_file *of = s->private; |
7da11279 | 4399 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 4400 | struct cgroup_pidlist *l; |
7da11279 | 4401 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 4402 | int index = 0, pid = *pos; |
4bac00d1 TH |
4403 | int *iter, ret; |
4404 | ||
4405 | mutex_lock(&cgrp->pidlist_mutex); | |
4406 | ||
4407 | /* | |
5d22444f | 4408 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 4409 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 4410 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
4411 | * could already have been destroyed. |
4412 | */ | |
5d22444f TH |
4413 | if (of->priv) |
4414 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
4415 | |
4416 | /* | |
4417 | * Either this is the first start() after open or the matching | |
4418 | * pidlist has been destroyed inbetween. Create a new one. | |
4419 | */ | |
5d22444f TH |
4420 | if (!of->priv) { |
4421 | ret = pidlist_array_load(cgrp, type, | |
4422 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
4423 | if (ret) |
4424 | return ERR_PTR(ret); | |
4425 | } | |
5d22444f | 4426 | l = of->priv; |
cc31edce | 4427 | |
cc31edce | 4428 | if (pid) { |
102a775e | 4429 | int end = l->length; |
20777766 | 4430 | |
cc31edce PM |
4431 | while (index < end) { |
4432 | int mid = (index + end) / 2; | |
afb2bc14 | 4433 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
4434 | index = mid; |
4435 | break; | |
afb2bc14 | 4436 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
4437 | index = mid + 1; |
4438 | else | |
4439 | end = mid; | |
4440 | } | |
4441 | } | |
4442 | /* If we're off the end of the array, we're done */ | |
102a775e | 4443 | if (index >= l->length) |
cc31edce PM |
4444 | return NULL; |
4445 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 4446 | iter = l->list + index; |
afb2bc14 | 4447 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
4448 | return iter; |
4449 | } | |
4450 | ||
102a775e | 4451 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 4452 | { |
2bd59d48 | 4453 | struct kernfs_open_file *of = s->private; |
5d22444f | 4454 | struct cgroup_pidlist *l = of->priv; |
62236858 | 4455 | |
5d22444f TH |
4456 | if (l) |
4457 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 4458 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 4459 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
4460 | } |
4461 | ||
102a775e | 4462 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 4463 | { |
2bd59d48 | 4464 | struct kernfs_open_file *of = s->private; |
5d22444f | 4465 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
4466 | pid_t *p = v; |
4467 | pid_t *end = l->list + l->length; | |
cc31edce PM |
4468 | /* |
4469 | * Advance to the next pid in the array. If this goes off the | |
4470 | * end, we're done | |
4471 | */ | |
4472 | p++; | |
4473 | if (p >= end) { | |
4474 | return NULL; | |
4475 | } else { | |
7da11279 | 4476 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
4477 | return p; |
4478 | } | |
4479 | } | |
4480 | ||
102a775e | 4481 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce | 4482 | { |
94ff212d JP |
4483 | seq_printf(s, "%d\n", *(int *)v); |
4484 | ||
4485 | return 0; | |
cc31edce | 4486 | } |
bbcb81d0 | 4487 | |
182446d0 TH |
4488 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
4489 | struct cftype *cft) | |
81a6a5cd | 4490 | { |
182446d0 | 4491 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
4492 | } |
4493 | ||
182446d0 TH |
4494 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
4495 | struct cftype *cft, u64 val) | |
6379c106 | 4496 | { |
6379c106 | 4497 | if (val) |
182446d0 | 4498 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 4499 | else |
182446d0 | 4500 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
4501 | return 0; |
4502 | } | |
4503 | ||
182446d0 TH |
4504 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
4505 | struct cftype *cft) | |
97978e6d | 4506 | { |
182446d0 | 4507 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4508 | } |
4509 | ||
182446d0 TH |
4510 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
4511 | struct cftype *cft, u64 val) | |
97978e6d DL |
4512 | { |
4513 | if (val) | |
182446d0 | 4514 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 4515 | else |
182446d0 | 4516 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4517 | return 0; |
4518 | } | |
4519 | ||
a14c6874 TH |
4520 | /* cgroup core interface files for the default hierarchy */ |
4521 | static struct cftype cgroup_dfl_base_files[] = { | |
81a6a5cd | 4522 | { |
d5c56ced | 4523 | .name = "cgroup.procs", |
6f60eade | 4524 | .file_offset = offsetof(struct cgroup, procs_file), |
6612f05b TH |
4525 | .seq_start = cgroup_pidlist_start, |
4526 | .seq_next = cgroup_pidlist_next, | |
4527 | .seq_stop = cgroup_pidlist_stop, | |
4528 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4529 | .private = CGROUP_FILE_PROCS, |
acbef755 | 4530 | .write = cgroup_procs_write, |
102a775e | 4531 | }, |
f8f22e53 TH |
4532 | { |
4533 | .name = "cgroup.controllers", | |
a14c6874 | 4534 | .flags = CFTYPE_ONLY_ON_ROOT, |
f8f22e53 TH |
4535 | .seq_show = cgroup_root_controllers_show, |
4536 | }, | |
4537 | { | |
4538 | .name = "cgroup.controllers", | |
a14c6874 | 4539 | .flags = CFTYPE_NOT_ON_ROOT, |
f8f22e53 TH |
4540 | .seq_show = cgroup_controllers_show, |
4541 | }, | |
4542 | { | |
4543 | .name = "cgroup.subtree_control", | |
f8f22e53 | 4544 | .seq_show = cgroup_subtree_control_show, |
451af504 | 4545 | .write = cgroup_subtree_control_write, |
f8f22e53 | 4546 | }, |
842b597e | 4547 | { |
4a07c222 | 4548 | .name = "cgroup.events", |
a14c6874 | 4549 | .flags = CFTYPE_NOT_ON_ROOT, |
6f60eade | 4550 | .file_offset = offsetof(struct cgroup, events_file), |
4a07c222 | 4551 | .seq_show = cgroup_events_show, |
842b597e | 4552 | }, |
a14c6874 TH |
4553 | { } /* terminate */ |
4554 | }; | |
d5c56ced | 4555 | |
a14c6874 TH |
4556 | /* cgroup core interface files for the legacy hierarchies */ |
4557 | static struct cftype cgroup_legacy_base_files[] = { | |
4558 | { | |
4559 | .name = "cgroup.procs", | |
4560 | .seq_start = cgroup_pidlist_start, | |
4561 | .seq_next = cgroup_pidlist_next, | |
4562 | .seq_stop = cgroup_pidlist_stop, | |
4563 | .seq_show = cgroup_pidlist_show, | |
4564 | .private = CGROUP_FILE_PROCS, | |
4565 | .write = cgroup_procs_write, | |
a14c6874 TH |
4566 | }, |
4567 | { | |
4568 | .name = "cgroup.clone_children", | |
4569 | .read_u64 = cgroup_clone_children_read, | |
4570 | .write_u64 = cgroup_clone_children_write, | |
4571 | }, | |
4572 | { | |
4573 | .name = "cgroup.sane_behavior", | |
4574 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4575 | .seq_show = cgroup_sane_behavior_show, | |
4576 | }, | |
d5c56ced TH |
4577 | { |
4578 | .name = "tasks", | |
6612f05b TH |
4579 | .seq_start = cgroup_pidlist_start, |
4580 | .seq_next = cgroup_pidlist_next, | |
4581 | .seq_stop = cgroup_pidlist_stop, | |
4582 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4583 | .private = CGROUP_FILE_TASKS, |
acbef755 | 4584 | .write = cgroup_tasks_write, |
d5c56ced TH |
4585 | }, |
4586 | { | |
4587 | .name = "notify_on_release", | |
d5c56ced TH |
4588 | .read_u64 = cgroup_read_notify_on_release, |
4589 | .write_u64 = cgroup_write_notify_on_release, | |
4590 | }, | |
6e6ff25b TH |
4591 | { |
4592 | .name = "release_agent", | |
a14c6874 | 4593 | .flags = CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 4594 | .seq_show = cgroup_release_agent_show, |
451af504 | 4595 | .write = cgroup_release_agent_write, |
5f469907 | 4596 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 4597 | }, |
db0416b6 | 4598 | { } /* terminate */ |
bbcb81d0 PM |
4599 | }; |
4600 | ||
0c21ead1 TH |
4601 | /* |
4602 | * css destruction is four-stage process. | |
4603 | * | |
4604 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
4605 | * Implemented in kill_css(). | |
4606 | * | |
4607 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
ec903c0c TH |
4608 | * and thus css_tryget_online() is guaranteed to fail, the css can be |
4609 | * offlined by invoking offline_css(). After offlining, the base ref is | |
4610 | * put. Implemented in css_killed_work_fn(). | |
0c21ead1 TH |
4611 | * |
4612 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
4613 | * accessors are inside RCU read sections. css_release() schedules the | |
4614 | * RCU callback. | |
4615 | * | |
4616 | * 4. After the grace period, the css can be freed. Implemented in | |
4617 | * css_free_work_fn(). | |
4618 | * | |
4619 | * It is actually hairier because both step 2 and 4 require process context | |
4620 | * and thus involve punting to css->destroy_work adding two additional | |
4621 | * steps to the already complex sequence. | |
4622 | */ | |
35ef10da | 4623 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
4624 | { |
4625 | struct cgroup_subsys_state *css = | |
35ef10da | 4626 | container_of(work, struct cgroup_subsys_state, destroy_work); |
01e58659 | 4627 | struct cgroup_subsys *ss = css->ss; |
0c21ead1 | 4628 | struct cgroup *cgrp = css->cgroup; |
6f60eade | 4629 | struct cgroup_file *cfile; |
48ddbe19 | 4630 | |
9a1049da TH |
4631 | percpu_ref_exit(&css->refcnt); |
4632 | ||
6f60eade TH |
4633 | list_for_each_entry(cfile, &css->files, node) |
4634 | kernfs_put(cfile->kn); | |
4635 | ||
01e58659 | 4636 | if (ss) { |
9d755d33 | 4637 | /* css free path */ |
01e58659 VD |
4638 | int id = css->id; |
4639 | ||
9d755d33 TH |
4640 | if (css->parent) |
4641 | css_put(css->parent); | |
0ae78e0b | 4642 | |
01e58659 VD |
4643 | ss->css_free(css); |
4644 | cgroup_idr_remove(&ss->css_idr, id); | |
9d755d33 TH |
4645 | cgroup_put(cgrp); |
4646 | } else { | |
4647 | /* cgroup free path */ | |
4648 | atomic_dec(&cgrp->root->nr_cgrps); | |
4649 | cgroup_pidlist_destroy_all(cgrp); | |
971ff493 | 4650 | cancel_work_sync(&cgrp->release_agent_work); |
9d755d33 | 4651 | |
d51f39b0 | 4652 | if (cgroup_parent(cgrp)) { |
9d755d33 TH |
4653 | /* |
4654 | * We get a ref to the parent, and put the ref when | |
4655 | * this cgroup is being freed, so it's guaranteed | |
4656 | * that the parent won't be destroyed before its | |
4657 | * children. | |
4658 | */ | |
d51f39b0 | 4659 | cgroup_put(cgroup_parent(cgrp)); |
9d755d33 TH |
4660 | kernfs_put(cgrp->kn); |
4661 | kfree(cgrp); | |
4662 | } else { | |
4663 | /* | |
4664 | * This is root cgroup's refcnt reaching zero, | |
4665 | * which indicates that the root should be | |
4666 | * released. | |
4667 | */ | |
4668 | cgroup_destroy_root(cgrp->root); | |
4669 | } | |
4670 | } | |
48ddbe19 TH |
4671 | } |
4672 | ||
0c21ead1 | 4673 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
4674 | { |
4675 | struct cgroup_subsys_state *css = | |
0c21ead1 | 4676 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 4677 | |
35ef10da | 4678 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 4679 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
4680 | } |
4681 | ||
25e15d83 | 4682 | static void css_release_work_fn(struct work_struct *work) |
d3daf28d TH |
4683 | { |
4684 | struct cgroup_subsys_state *css = | |
25e15d83 | 4685 | container_of(work, struct cgroup_subsys_state, destroy_work); |
15a4c835 | 4686 | struct cgroup_subsys *ss = css->ss; |
9d755d33 | 4687 | struct cgroup *cgrp = css->cgroup; |
15a4c835 | 4688 | |
1fed1b2e TH |
4689 | mutex_lock(&cgroup_mutex); |
4690 | ||
de3f0341 | 4691 | css->flags |= CSS_RELEASED; |
1fed1b2e TH |
4692 | list_del_rcu(&css->sibling); |
4693 | ||
9d755d33 TH |
4694 | if (ss) { |
4695 | /* css release path */ | |
01e58659 | 4696 | cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
7d172cc8 TH |
4697 | if (ss->css_released) |
4698 | ss->css_released(css); | |
9d755d33 TH |
4699 | } else { |
4700 | /* cgroup release path */ | |
9d755d33 TH |
4701 | cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
4702 | cgrp->id = -1; | |
a4189487 LZ |
4703 | |
4704 | /* | |
4705 | * There are two control paths which try to determine | |
4706 | * cgroup from dentry without going through kernfs - | |
4707 | * cgroupstats_build() and css_tryget_online_from_dir(). | |
4708 | * Those are supported by RCU protecting clearing of | |
4709 | * cgrp->kn->priv backpointer. | |
4710 | */ | |
4711 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); | |
9d755d33 | 4712 | } |
d3daf28d | 4713 | |
1fed1b2e TH |
4714 | mutex_unlock(&cgroup_mutex); |
4715 | ||
0c21ead1 | 4716 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
4717 | } |
4718 | ||
d3daf28d TH |
4719 | static void css_release(struct percpu_ref *ref) |
4720 | { | |
4721 | struct cgroup_subsys_state *css = | |
4722 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4723 | ||
25e15d83 TH |
4724 | INIT_WORK(&css->destroy_work, css_release_work_fn); |
4725 | queue_work(cgroup_destroy_wq, &css->destroy_work); | |
d3daf28d TH |
4726 | } |
4727 | ||
ddfcadab TH |
4728 | static void init_and_link_css(struct cgroup_subsys_state *css, |
4729 | struct cgroup_subsys *ss, struct cgroup *cgrp) | |
ddbcc7e8 | 4730 | { |
0cb51d71 TH |
4731 | lockdep_assert_held(&cgroup_mutex); |
4732 | ||
ddfcadab TH |
4733 | cgroup_get(cgrp); |
4734 | ||
d5c419b6 | 4735 | memset(css, 0, sizeof(*css)); |
bd89aabc | 4736 | css->cgroup = cgrp; |
72c97e54 | 4737 | css->ss = ss; |
d5c419b6 TH |
4738 | INIT_LIST_HEAD(&css->sibling); |
4739 | INIT_LIST_HEAD(&css->children); | |
6f60eade | 4740 | INIT_LIST_HEAD(&css->files); |
0cb51d71 | 4741 | css->serial_nr = css_serial_nr_next++; |
0ae78e0b | 4742 | |
d51f39b0 TH |
4743 | if (cgroup_parent(cgrp)) { |
4744 | css->parent = cgroup_css(cgroup_parent(cgrp), ss); | |
ddfcadab | 4745 | css_get(css->parent); |
ddfcadab | 4746 | } |
48ddbe19 | 4747 | |
ca8bdcaf | 4748 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
4749 | } |
4750 | ||
2a4ac633 | 4751 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 4752 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4753 | { |
623f926b | 4754 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
4755 | int ret = 0; |
4756 | ||
a31f2d3f TH |
4757 | lockdep_assert_held(&cgroup_mutex); |
4758 | ||
92fb9748 | 4759 | if (ss->css_online) |
eb95419b | 4760 | ret = ss->css_online(css); |
ae7f164a | 4761 | if (!ret) { |
eb95419b | 4762 | css->flags |= CSS_ONLINE; |
aec25020 | 4763 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 4764 | } |
b1929db4 | 4765 | return ret; |
a31f2d3f TH |
4766 | } |
4767 | ||
2a4ac633 | 4768 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 4769 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4770 | { |
623f926b | 4771 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f TH |
4772 | |
4773 | lockdep_assert_held(&cgroup_mutex); | |
4774 | ||
4775 | if (!(css->flags & CSS_ONLINE)) | |
4776 | return; | |
4777 | ||
d7eeac19 | 4778 | if (ss->css_offline) |
eb95419b | 4779 | ss->css_offline(css); |
a31f2d3f | 4780 | |
eb95419b | 4781 | css->flags &= ~CSS_ONLINE; |
e3297803 | 4782 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
f8f22e53 TH |
4783 | |
4784 | wake_up_all(&css->cgroup->offline_waitq); | |
a31f2d3f TH |
4785 | } |
4786 | ||
c81c925a TH |
4787 | /** |
4788 | * create_css - create a cgroup_subsys_state | |
4789 | * @cgrp: the cgroup new css will be associated with | |
4790 | * @ss: the subsys of new css | |
f63070d3 | 4791 | * @visible: whether to create control knobs for the new css or not |
c81c925a TH |
4792 | * |
4793 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
f63070d3 TH |
4794 | * css is online and installed in @cgrp with all interface files created if |
4795 | * @visible. Returns 0 on success, -errno on failure. | |
c81c925a | 4796 | */ |
f63070d3 TH |
4797 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
4798 | bool visible) | |
c81c925a | 4799 | { |
d51f39b0 | 4800 | struct cgroup *parent = cgroup_parent(cgrp); |
1fed1b2e | 4801 | struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
c81c925a TH |
4802 | struct cgroup_subsys_state *css; |
4803 | int err; | |
4804 | ||
c81c925a TH |
4805 | lockdep_assert_held(&cgroup_mutex); |
4806 | ||
1fed1b2e | 4807 | css = ss->css_alloc(parent_css); |
c81c925a TH |
4808 | if (IS_ERR(css)) |
4809 | return PTR_ERR(css); | |
4810 | ||
ddfcadab | 4811 | init_and_link_css(css, ss, cgrp); |
a2bed820 | 4812 | |
2aad2a86 | 4813 | err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
c81c925a | 4814 | if (err) |
3eb59ec6 | 4815 | goto err_free_css; |
c81c925a | 4816 | |
cf780b7d | 4817 | err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
15a4c835 TH |
4818 | if (err < 0) |
4819 | goto err_free_percpu_ref; | |
4820 | css->id = err; | |
c81c925a | 4821 | |
f63070d3 | 4822 | if (visible) { |
4df8dc90 | 4823 | err = css_populate_dir(css, NULL); |
f63070d3 TH |
4824 | if (err) |
4825 | goto err_free_id; | |
4826 | } | |
15a4c835 TH |
4827 | |
4828 | /* @css is ready to be brought online now, make it visible */ | |
1fed1b2e | 4829 | list_add_tail_rcu(&css->sibling, &parent_css->children); |
15a4c835 | 4830 | cgroup_idr_replace(&ss->css_idr, css, css->id); |
c81c925a TH |
4831 | |
4832 | err = online_css(css); | |
4833 | if (err) | |
1fed1b2e | 4834 | goto err_list_del; |
94419627 | 4835 | |
c81c925a | 4836 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
d51f39b0 | 4837 | cgroup_parent(parent)) { |
ed3d261b | 4838 | pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", |
a2a1f9ea | 4839 | current->comm, current->pid, ss->name); |
c81c925a | 4840 | if (!strcmp(ss->name, "memory")) |
ed3d261b | 4841 | pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
c81c925a TH |
4842 | ss->warned_broken_hierarchy = true; |
4843 | } | |
4844 | ||
4845 | return 0; | |
4846 | ||
1fed1b2e TH |
4847 | err_list_del: |
4848 | list_del_rcu(&css->sibling); | |
4df8dc90 | 4849 | css_clear_dir(css, NULL); |
15a4c835 TH |
4850 | err_free_id: |
4851 | cgroup_idr_remove(&ss->css_idr, css->id); | |
3eb59ec6 | 4852 | err_free_percpu_ref: |
9a1049da | 4853 | percpu_ref_exit(&css->refcnt); |
3eb59ec6 | 4854 | err_free_css: |
a2bed820 | 4855 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
c81c925a TH |
4856 | return err; |
4857 | } | |
4858 | ||
b3bfd983 TH |
4859 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
4860 | umode_t mode) | |
ddbcc7e8 | 4861 | { |
a9746d8d TH |
4862 | struct cgroup *parent, *cgrp; |
4863 | struct cgroup_root *root; | |
ddbcc7e8 | 4864 | struct cgroup_subsys *ss; |
2bd59d48 | 4865 | struct kernfs_node *kn; |
b3bfd983 | 4866 | int ssid, ret; |
ddbcc7e8 | 4867 | |
71b1fb5c AC |
4868 | /* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable. |
4869 | */ | |
4870 | if (strchr(name, '\n')) | |
4871 | return -EINVAL; | |
4872 | ||
a9746d8d TH |
4873 | parent = cgroup_kn_lock_live(parent_kn); |
4874 | if (!parent) | |
4875 | return -ENODEV; | |
4876 | root = parent->root; | |
ddbcc7e8 | 4877 | |
0a950f65 | 4878 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc | 4879 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
ba0f4d76 TH |
4880 | if (!cgrp) { |
4881 | ret = -ENOMEM; | |
4882 | goto out_unlock; | |
0ab02ca8 LZ |
4883 | } |
4884 | ||
2aad2a86 | 4885 | ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
9d755d33 TH |
4886 | if (ret) |
4887 | goto out_free_cgrp; | |
4888 | ||
0ab02ca8 LZ |
4889 | /* |
4890 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
4891 | * a half-baked cgroup. | |
4892 | */ | |
cf780b7d | 4893 | cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
0ab02ca8 | 4894 | if (cgrp->id < 0) { |
ba0f4d76 | 4895 | ret = -ENOMEM; |
9d755d33 | 4896 | goto out_cancel_ref; |
976c06bc TH |
4897 | } |
4898 | ||
cc31edce | 4899 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4900 | |
9d800df1 | 4901 | cgrp->self.parent = &parent->self; |
ba0f4d76 | 4902 | cgrp->root = root; |
ddbcc7e8 | 4903 | |
b6abdb0e LZ |
4904 | if (notify_on_release(parent)) |
4905 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4906 | ||
2260e7fc TH |
4907 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4908 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4909 | |
2bd59d48 | 4910 | /* create the directory */ |
e61734c5 | 4911 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 | 4912 | if (IS_ERR(kn)) { |
ba0f4d76 TH |
4913 | ret = PTR_ERR(kn); |
4914 | goto out_free_id; | |
2bd59d48 TH |
4915 | } |
4916 | cgrp->kn = kn; | |
ddbcc7e8 | 4917 | |
4e139afc | 4918 | /* |
6f30558f TH |
4919 | * This extra ref will be put in cgroup_free_fn() and guarantees |
4920 | * that @cgrp->kn is always accessible. | |
4e139afc | 4921 | */ |
6f30558f | 4922 | kernfs_get(kn); |
ddbcc7e8 | 4923 | |
0cb51d71 | 4924 | cgrp->self.serial_nr = css_serial_nr_next++; |
53fa5261 | 4925 | |
4e139afc | 4926 | /* allocation complete, commit to creation */ |
d5c419b6 | 4927 | list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
3c9c825b | 4928 | atomic_inc(&root->nr_cgrps); |
59f5296b | 4929 | cgroup_get(parent); |
415cf07a | 4930 | |
0d80255e TH |
4931 | /* |
4932 | * @cgrp is now fully operational. If something fails after this | |
4933 | * point, it'll be released via the normal destruction path. | |
4934 | */ | |
6fa4918d | 4935 | cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
4e96ee8e | 4936 | |
ba0f4d76 TH |
4937 | ret = cgroup_kn_set_ugid(kn); |
4938 | if (ret) | |
4939 | goto out_destroy; | |
49957f8e | 4940 | |
4df8dc90 | 4941 | ret = css_populate_dir(&cgrp->self, NULL); |
ba0f4d76 TH |
4942 | if (ret) |
4943 | goto out_destroy; | |
628f7cd4 | 4944 | |
9d403e99 | 4945 | /* let's create and online css's */ |
b85d2040 | 4946 | for_each_subsys(ss, ssid) { |
f392e51c | 4947 | if (parent->child_subsys_mask & (1 << ssid)) { |
f63070d3 TH |
4948 | ret = create_css(cgrp, ss, |
4949 | parent->subtree_control & (1 << ssid)); | |
ba0f4d76 TH |
4950 | if (ret) |
4951 | goto out_destroy; | |
b85d2040 | 4952 | } |
a8638030 | 4953 | } |
ddbcc7e8 | 4954 | |
bd53d617 TH |
4955 | /* |
4956 | * On the default hierarchy, a child doesn't automatically inherit | |
667c2491 | 4957 | * subtree_control from the parent. Each is configured manually. |
bd53d617 | 4958 | */ |
667c2491 TH |
4959 | if (!cgroup_on_dfl(cgrp)) { |
4960 | cgrp->subtree_control = parent->subtree_control; | |
4961 | cgroup_refresh_child_subsys_mask(cgrp); | |
4962 | } | |
2bd59d48 | 4963 | |
2bd59d48 | 4964 | kernfs_activate(kn); |
ddbcc7e8 | 4965 | |
ba0f4d76 TH |
4966 | ret = 0; |
4967 | goto out_unlock; | |
ddbcc7e8 | 4968 | |
ba0f4d76 | 4969 | out_free_id: |
6fa4918d | 4970 | cgroup_idr_remove(&root->cgroup_idr, cgrp->id); |
9d755d33 | 4971 | out_cancel_ref: |
9a1049da | 4972 | percpu_ref_exit(&cgrp->self.refcnt); |
ba0f4d76 | 4973 | out_free_cgrp: |
bd89aabc | 4974 | kfree(cgrp); |
ba0f4d76 | 4975 | out_unlock: |
a9746d8d | 4976 | cgroup_kn_unlock(parent_kn); |
ba0f4d76 | 4977 | return ret; |
4b8b47eb | 4978 | |
ba0f4d76 | 4979 | out_destroy: |
4b8b47eb | 4980 | cgroup_destroy_locked(cgrp); |
ba0f4d76 | 4981 | goto out_unlock; |
ddbcc7e8 PM |
4982 | } |
4983 | ||
223dbc38 TH |
4984 | /* |
4985 | * This is called when the refcnt of a css is confirmed to be killed. | |
249f3468 TH |
4986 | * css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
4987 | * initate destruction and put the css ref from kill_css(). | |
223dbc38 TH |
4988 | */ |
4989 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 4990 | { |
223dbc38 TH |
4991 | struct cgroup_subsys_state *css = |
4992 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
d3daf28d | 4993 | |
f20104de | 4994 | mutex_lock(&cgroup_mutex); |
09a503ea | 4995 | offline_css(css); |
f20104de | 4996 | mutex_unlock(&cgroup_mutex); |
09a503ea | 4997 | |
09a503ea | 4998 | css_put(css); |
d3daf28d TH |
4999 | } |
5000 | ||
223dbc38 TH |
5001 | /* css kill confirmation processing requires process context, bounce */ |
5002 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
5003 | { |
5004 | struct cgroup_subsys_state *css = | |
5005 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
5006 | ||
223dbc38 | 5007 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 5008 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
5009 | } |
5010 | ||
f392e51c TH |
5011 | /** |
5012 | * kill_css - destroy a css | |
5013 | * @css: css to destroy | |
5014 | * | |
5015 | * This function initiates destruction of @css by removing cgroup interface | |
5016 | * files and putting its base reference. ->css_offline() will be invoked | |
ec903c0c TH |
5017 | * asynchronously once css_tryget_online() is guaranteed to fail and when |
5018 | * the reference count reaches zero, @css will be released. | |
f392e51c TH |
5019 | */ |
5020 | static void kill_css(struct cgroup_subsys_state *css) | |
edae0c33 | 5021 | { |
01f6474c | 5022 | lockdep_assert_held(&cgroup_mutex); |
94419627 | 5023 | |
2bd59d48 TH |
5024 | /* |
5025 | * This must happen before css is disassociated with its cgroup. | |
5026 | * See seq_css() for details. | |
5027 | */ | |
4df8dc90 | 5028 | css_clear_dir(css, NULL); |
3c14f8b4 | 5029 | |
edae0c33 TH |
5030 | /* |
5031 | * Killing would put the base ref, but we need to keep it alive | |
5032 | * until after ->css_offline(). | |
5033 | */ | |
5034 | css_get(css); | |
5035 | ||
5036 | /* | |
5037 | * cgroup core guarantees that, by the time ->css_offline() is | |
5038 | * invoked, no new css reference will be given out via | |
ec903c0c | 5039 | * css_tryget_online(). We can't simply call percpu_ref_kill() and |
edae0c33 TH |
5040 | * proceed to offlining css's because percpu_ref_kill() doesn't |
5041 | * guarantee that the ref is seen as killed on all CPUs on return. | |
5042 | * | |
5043 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
5044 | * css is confirmed to be seen as killed on all CPUs. | |
5045 | */ | |
5046 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
5047 | } |
5048 | ||
5049 | /** | |
5050 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
5051 | * @cgrp: cgroup to be destroyed | |
5052 | * | |
5053 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
5054 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
ec903c0c TH |
5055 | * guarantee that css_tryget_online() won't succeed by the time |
5056 | * ->css_offline() is invoked. To satisfy all the requirements, | |
5057 | * destruction is implemented in the following two steps. | |
d3daf28d TH |
5058 | * |
5059 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
5060 | * userland visible parts and start killing the percpu refcnts of | |
5061 | * css's. Set up so that the next stage will be kicked off once all | |
5062 | * the percpu refcnts are confirmed to be killed. | |
5063 | * | |
5064 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
5065 | * rest of destruction. Once all cgroup references are gone, the | |
5066 | * cgroup is RCU-freed. | |
5067 | * | |
5068 | * This function implements s1. After this step, @cgrp is gone as far as | |
5069 | * the userland is concerned and a new cgroup with the same name may be | |
5070 | * created. As cgroup doesn't care about the names internally, this | |
5071 | * doesn't cause any problem. | |
5072 | */ | |
42809dd4 TH |
5073 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
5074 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 5075 | { |
2bd59d48 | 5076 | struct cgroup_subsys_state *css; |
1c6727af | 5077 | int ssid; |
ddbcc7e8 | 5078 | |
42809dd4 TH |
5079 | lockdep_assert_held(&cgroup_mutex); |
5080 | ||
91486f61 TH |
5081 | /* |
5082 | * Only migration can raise populated from zero and we're already | |
5083 | * holding cgroup_mutex. | |
5084 | */ | |
5085 | if (cgroup_is_populated(cgrp)) | |
ddbcc7e8 | 5086 | return -EBUSY; |
a043e3b2 | 5087 | |
bb78a92f | 5088 | /* |
d5c419b6 TH |
5089 | * Make sure there's no live children. We can't test emptiness of |
5090 | * ->self.children as dead children linger on it while being | |
5091 | * drained; otherwise, "rmdir parent/child parent" may fail. | |
bb78a92f | 5092 | */ |
f3d46500 | 5093 | if (css_has_online_children(&cgrp->self)) |
bb78a92f HD |
5094 | return -EBUSY; |
5095 | ||
455050d2 TH |
5096 | /* |
5097 | * Mark @cgrp dead. This prevents further task migration and child | |
de3f0341 | 5098 | * creation by disabling cgroup_lock_live_group(). |
455050d2 | 5099 | */ |
184faf32 | 5100 | cgrp->self.flags &= ~CSS_ONLINE; |
ddbcc7e8 | 5101 | |
249f3468 | 5102 | /* initiate massacre of all css's */ |
1c6727af TH |
5103 | for_each_css(css, ssid, cgrp) |
5104 | kill_css(css); | |
455050d2 | 5105 | |
455050d2 | 5106 | /* |
01f6474c TH |
5107 | * Remove @cgrp directory along with the base files. @cgrp has an |
5108 | * extra ref on its kn. | |
f20104de | 5109 | */ |
01f6474c | 5110 | kernfs_remove(cgrp->kn); |
f20104de | 5111 | |
d51f39b0 | 5112 | check_for_release(cgroup_parent(cgrp)); |
2bd59d48 | 5113 | |
249f3468 | 5114 | /* put the base reference */ |
9d755d33 | 5115 | percpu_ref_kill(&cgrp->self.refcnt); |
455050d2 | 5116 | |
ea15f8cc TH |
5117 | return 0; |
5118 | }; | |
5119 | ||
2bd59d48 | 5120 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 5121 | { |
a9746d8d | 5122 | struct cgroup *cgrp; |
2bd59d48 | 5123 | int ret = 0; |
42809dd4 | 5124 | |
a9746d8d TH |
5125 | cgrp = cgroup_kn_lock_live(kn); |
5126 | if (!cgrp) | |
5127 | return 0; | |
42809dd4 | 5128 | |
a9746d8d | 5129 | ret = cgroup_destroy_locked(cgrp); |
2bb566cb | 5130 | |
a9746d8d | 5131 | cgroup_kn_unlock(kn); |
42809dd4 | 5132 | return ret; |
8e3f6541 TH |
5133 | } |
5134 | ||
2bd59d48 TH |
5135 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
5136 | .remount_fs = cgroup_remount, | |
5137 | .show_options = cgroup_show_options, | |
5138 | .mkdir = cgroup_mkdir, | |
5139 | .rmdir = cgroup_rmdir, | |
5140 | .rename = cgroup_rename, | |
5141 | }; | |
5142 | ||
15a4c835 | 5143 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
ddbcc7e8 | 5144 | { |
ddbcc7e8 | 5145 | struct cgroup_subsys_state *css; |
cfe36bde DC |
5146 | |
5147 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 5148 | |
648bb56d TH |
5149 | mutex_lock(&cgroup_mutex); |
5150 | ||
15a4c835 | 5151 | idr_init(&ss->css_idr); |
0adb0704 | 5152 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 5153 | |
3dd06ffa TH |
5154 | /* Create the root cgroup state for this subsystem */ |
5155 | ss->root = &cgrp_dfl_root; | |
5156 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
5157 | /* We don't handle early failures gracefully */ |
5158 | BUG_ON(IS_ERR(css)); | |
ddfcadab | 5159 | init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
3b514d24 TH |
5160 | |
5161 | /* | |
5162 | * Root csses are never destroyed and we can't initialize | |
5163 | * percpu_ref during early init. Disable refcnting. | |
5164 | */ | |
5165 | css->flags |= CSS_NO_REF; | |
5166 | ||
15a4c835 | 5167 | if (early) { |
9395a450 | 5168 | /* allocation can't be done safely during early init */ |
15a4c835 TH |
5169 | css->id = 1; |
5170 | } else { | |
5171 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); | |
5172 | BUG_ON(css->id < 0); | |
5173 | } | |
ddbcc7e8 | 5174 | |
e8d55fde | 5175 | /* Update the init_css_set to contain a subsys |
817929ec | 5176 | * pointer to this state - since the subsystem is |
e8d55fde | 5177 | * newly registered, all tasks and hence the |
3dd06ffa | 5178 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 5179 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 | 5180 | |
cb4a3167 AS |
5181 | have_fork_callback |= (bool)ss->fork << ss->id; |
5182 | have_exit_callback |= (bool)ss->exit << ss->id; | |
7e47682e | 5183 | have_canfork_callback |= (bool)ss->can_fork << ss->id; |
ddbcc7e8 | 5184 | |
e8d55fde LZ |
5185 | /* At system boot, before all subsystems have been |
5186 | * registered, no tasks have been forked, so we don't | |
5187 | * need to invoke fork callbacks here. */ | |
5188 | BUG_ON(!list_empty(&init_task.tasks)); | |
5189 | ||
ae7f164a | 5190 | BUG_ON(online_css(css)); |
a8638030 | 5191 | |
cf5d5941 BB |
5192 | mutex_unlock(&cgroup_mutex); |
5193 | } | |
cf5d5941 | 5194 | |
ddbcc7e8 | 5195 | /** |
a043e3b2 LZ |
5196 | * cgroup_init_early - cgroup initialization at system boot |
5197 | * | |
5198 | * Initialize cgroups at system boot, and initialize any | |
5199 | * subsystems that request early init. | |
ddbcc7e8 PM |
5200 | */ |
5201 | int __init cgroup_init_early(void) | |
5202 | { | |
7b9a6ba5 | 5203 | static struct cgroup_sb_opts __initdata opts; |
30159ec7 | 5204 | struct cgroup_subsys *ss; |
ddbcc7e8 | 5205 | int i; |
30159ec7 | 5206 | |
3dd06ffa | 5207 | init_cgroup_root(&cgrp_dfl_root, &opts); |
3b514d24 TH |
5208 | cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
5209 | ||
a4ea1cc9 | 5210 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 5211 | |
3ed80a62 | 5212 | for_each_subsys(ss, i) { |
aec25020 | 5213 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
5214 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
5215 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 5216 | ss->id, ss->name); |
073219e9 TH |
5217 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
5218 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
5219 | ||
aec25020 | 5220 | ss->id = i; |
073219e9 | 5221 | ss->name = cgroup_subsys_name[i]; |
3e1d2eed TH |
5222 | if (!ss->legacy_name) |
5223 | ss->legacy_name = cgroup_subsys_name[i]; | |
ddbcc7e8 PM |
5224 | |
5225 | if (ss->early_init) | |
15a4c835 | 5226 | cgroup_init_subsys(ss, true); |
ddbcc7e8 PM |
5227 | } |
5228 | return 0; | |
5229 | } | |
5230 | ||
a3e72739 TH |
5231 | static unsigned long cgroup_disable_mask __initdata; |
5232 | ||
ddbcc7e8 | 5233 | /** |
a043e3b2 LZ |
5234 | * cgroup_init - cgroup initialization |
5235 | * | |
5236 | * Register cgroup filesystem and /proc file, and initialize | |
5237 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
5238 | */ |
5239 | int __init cgroup_init(void) | |
5240 | { | |
30159ec7 | 5241 | struct cgroup_subsys *ss; |
0ac801fe | 5242 | unsigned long key; |
172a2c06 | 5243 | int ssid, err; |
ddbcc7e8 | 5244 | |
1ed13287 | 5245 | BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
a14c6874 TH |
5246 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
5247 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); | |
ddbcc7e8 | 5248 | |
54e7b4eb | 5249 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 5250 | |
82fe9b0d TH |
5251 | /* Add init_css_set to the hash table */ |
5252 | key = css_set_hash(init_css_set.subsys); | |
5253 | hash_add(css_set_table, &init_css_set.hlist, key); | |
5254 | ||
3dd06ffa | 5255 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 5256 | |
54e7b4eb TH |
5257 | mutex_unlock(&cgroup_mutex); |
5258 | ||
172a2c06 | 5259 | for_each_subsys(ss, ssid) { |
15a4c835 TH |
5260 | if (ss->early_init) { |
5261 | struct cgroup_subsys_state *css = | |
5262 | init_css_set.subsys[ss->id]; | |
5263 | ||
5264 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, | |
5265 | GFP_KERNEL); | |
5266 | BUG_ON(css->id < 0); | |
5267 | } else { | |
5268 | cgroup_init_subsys(ss, false); | |
5269 | } | |
172a2c06 | 5270 | |
2d8f243a TH |
5271 | list_add_tail(&init_css_set.e_cset_node[ssid], |
5272 | &cgrp_dfl_root.cgrp.e_csets[ssid]); | |
172a2c06 TH |
5273 | |
5274 | /* | |
c731ae1d LZ |
5275 | * Setting dfl_root subsys_mask needs to consider the |
5276 | * disabled flag and cftype registration needs kmalloc, | |
5277 | * both of which aren't available during early_init. | |
172a2c06 | 5278 | */ |
a3e72739 TH |
5279 | if (cgroup_disable_mask & (1 << ssid)) { |
5280 | static_branch_disable(cgroup_subsys_enabled_key[ssid]); | |
5281 | printk(KERN_INFO "Disabling %s control group subsystem\n", | |
5282 | ss->name); | |
a8ddc821 | 5283 | continue; |
a3e72739 | 5284 | } |
a8ddc821 TH |
5285 | |
5286 | cgrp_dfl_root.subsys_mask |= 1 << ss->id; | |
5287 | ||
5288 | if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes) | |
5289 | ss->dfl_cftypes = ss->legacy_cftypes; | |
5290 | ||
5de4fa13 TH |
5291 | if (!ss->dfl_cftypes) |
5292 | cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id; | |
5293 | ||
a8ddc821 TH |
5294 | if (ss->dfl_cftypes == ss->legacy_cftypes) { |
5295 | WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); | |
5296 | } else { | |
5297 | WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); | |
5298 | WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); | |
c731ae1d | 5299 | } |
295458e6 VD |
5300 | |
5301 | if (ss->bind) | |
5302 | ss->bind(init_css_set.subsys[ssid]); | |
676db4af GK |
5303 | } |
5304 | ||
f9bb4882 EB |
5305 | err = sysfs_create_mount_point(fs_kobj, "cgroup"); |
5306 | if (err) | |
5307 | return err; | |
676db4af | 5308 | |
ddbcc7e8 | 5309 | err = register_filesystem(&cgroup_fs_type); |
676db4af | 5310 | if (err < 0) { |
f9bb4882 | 5311 | sysfs_remove_mount_point(fs_kobj, "cgroup"); |
2bd59d48 | 5312 | return err; |
676db4af | 5313 | } |
ddbcc7e8 | 5314 | |
46ae220b | 5315 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 5316 | return 0; |
ddbcc7e8 | 5317 | } |
b4f48b63 | 5318 | |
e5fca243 TH |
5319 | static int __init cgroup_wq_init(void) |
5320 | { | |
5321 | /* | |
5322 | * There isn't much point in executing destruction path in | |
5323 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 5324 | * Use 1 for @max_active. |
e5fca243 TH |
5325 | * |
5326 | * We would prefer to do this in cgroup_init() above, but that | |
5327 | * is called before init_workqueues(): so leave this until after. | |
5328 | */ | |
1a11533f | 5329 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 5330 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
5331 | |
5332 | /* | |
5333 | * Used to destroy pidlists and separate to serve as flush domain. | |
5334 | * Cap @max_active to 1 too. | |
5335 | */ | |
5336 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
5337 | 0, 1); | |
5338 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
5339 | ||
e5fca243 TH |
5340 | return 0; |
5341 | } | |
5342 | core_initcall(cgroup_wq_init); | |
5343 | ||
a424316c PM |
5344 | /* |
5345 | * proc_cgroup_show() | |
5346 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
5347 | * - Used for /proc/<pid>/cgroup. | |
a424316c | 5348 | */ |
006f4ac4 ZL |
5349 | int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
5350 | struct pid *pid, struct task_struct *tsk) | |
a424316c | 5351 | { |
e61734c5 | 5352 | char *buf, *path; |
a424316c | 5353 | int retval; |
3dd06ffa | 5354 | struct cgroup_root *root; |
a424316c PM |
5355 | |
5356 | retval = -ENOMEM; | |
e61734c5 | 5357 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
5358 | if (!buf) |
5359 | goto out; | |
5360 | ||
a424316c | 5361 | mutex_lock(&cgroup_mutex); |
f0d9a5f1 | 5362 | spin_lock_bh(&css_set_lock); |
a424316c | 5363 | |
985ed670 | 5364 | for_each_root(root) { |
a424316c | 5365 | struct cgroup_subsys *ss; |
bd89aabc | 5366 | struct cgroup *cgrp; |
b85d2040 | 5367 | int ssid, count = 0; |
a424316c | 5368 | |
a2dd4247 | 5369 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible) |
985ed670 TH |
5370 | continue; |
5371 | ||
2c6ab6d2 | 5372 | seq_printf(m, "%d:", root->hierarchy_id); |
d98817d4 TH |
5373 | if (root != &cgrp_dfl_root) |
5374 | for_each_subsys(ss, ssid) | |
5375 | if (root->subsys_mask & (1 << ssid)) | |
5376 | seq_printf(m, "%s%s", count++ ? "," : "", | |
3e1d2eed | 5377 | ss->legacy_name); |
c6d57f33 PM |
5378 | if (strlen(root->name)) |
5379 | seq_printf(m, "%sname=%s", count ? "," : "", | |
5380 | root->name); | |
a424316c | 5381 | seq_putc(m, ':'); |
2e91fa7f | 5382 | |
7717f7ba | 5383 | cgrp = task_cgroup_from_root(tsk, root); |
2e91fa7f TH |
5384 | |
5385 | /* | |
5386 | * On traditional hierarchies, all zombie tasks show up as | |
5387 | * belonging to the root cgroup. On the default hierarchy, | |
5388 | * while a zombie doesn't show up in "cgroup.procs" and | |
5389 | * thus can't be migrated, its /proc/PID/cgroup keeps | |
5390 | * reporting the cgroup it belonged to before exiting. If | |
5391 | * the cgroup is removed before the zombie is reaped, | |
5392 | * " (deleted)" is appended to the cgroup path. | |
5393 | */ | |
5394 | if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) { | |
5395 | path = cgroup_path(cgrp, buf, PATH_MAX); | |
5396 | if (!path) { | |
5397 | retval = -ENAMETOOLONG; | |
5398 | goto out_unlock; | |
5399 | } | |
5400 | } else { | |
5401 | path = "/"; | |
e61734c5 | 5402 | } |
2e91fa7f | 5403 | |
e61734c5 | 5404 | seq_puts(m, path); |
2e91fa7f TH |
5405 | |
5406 | if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp)) | |
5407 | seq_puts(m, " (deleted)\n"); | |
5408 | else | |
5409 | seq_putc(m, '\n'); | |
a424316c PM |
5410 | } |
5411 | ||
006f4ac4 | 5412 | retval = 0; |
a424316c | 5413 | out_unlock: |
f0d9a5f1 | 5414 | spin_unlock_bh(&css_set_lock); |
a424316c | 5415 | mutex_unlock(&cgroup_mutex); |
a424316c PM |
5416 | kfree(buf); |
5417 | out: | |
5418 | return retval; | |
5419 | } | |
5420 | ||
a424316c PM |
5421 | /* Display information about each subsystem and each hierarchy */ |
5422 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
5423 | { | |
30159ec7 | 5424 | struct cgroup_subsys *ss; |
a424316c | 5425 | int i; |
a424316c | 5426 | |
8bab8dde | 5427 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
5428 | /* |
5429 | * ideally we don't want subsystems moving around while we do this. | |
5430 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5431 | * subsys/hierarchy state. | |
5432 | */ | |
a424316c | 5433 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
5434 | |
5435 | for_each_subsys(ss, i) | |
2c6ab6d2 | 5436 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
3e1d2eed | 5437 | ss->legacy_name, ss->root->hierarchy_id, |
fc5ed1e9 TH |
5438 | atomic_read(&ss->root->nr_cgrps), |
5439 | cgroup_ssid_enabled(i)); | |
30159ec7 | 5440 | |
a424316c PM |
5441 | mutex_unlock(&cgroup_mutex); |
5442 | return 0; | |
5443 | } | |
5444 | ||
5445 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5446 | { | |
9dce07f1 | 5447 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5448 | } |
5449 | ||
828c0950 | 5450 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5451 | .open = cgroupstats_open, |
5452 | .read = seq_read, | |
5453 | .llseek = seq_lseek, | |
5454 | .release = single_release, | |
5455 | }; | |
5456 | ||
7e47682e AS |
5457 | static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i) |
5458 | { | |
5459 | if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END) | |
5460 | return &ss_priv[i - CGROUP_CANFORK_START]; | |
5461 | return NULL; | |
5462 | } | |
5463 | ||
5464 | static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i) | |
5465 | { | |
5466 | void **private = subsys_canfork_priv_p(ss_priv, i); | |
5467 | return private ? *private : NULL; | |
5468 | } | |
5469 | ||
b4f48b63 | 5470 | /** |
eaf797ab | 5471 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 5472 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 5473 | * |
eaf797ab TH |
5474 | * A task is associated with the init_css_set until cgroup_post_fork() |
5475 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
5476 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
5477 | */ |
5478 | void cgroup_fork(struct task_struct *child) | |
5479 | { | |
eaf797ab | 5480 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 5481 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5482 | } |
5483 | ||
7e47682e AS |
5484 | /** |
5485 | * cgroup_can_fork - called on a new task before the process is exposed | |
5486 | * @child: the task in question. | |
5487 | * | |
5488 | * This calls the subsystem can_fork() callbacks. If the can_fork() callback | |
5489 | * returns an error, the fork aborts with that error code. This allows for | |
5490 | * a cgroup subsystem to conditionally allow or deny new forks. | |
5491 | */ | |
5492 | int cgroup_can_fork(struct task_struct *child, | |
5493 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5494 | { | |
5495 | struct cgroup_subsys *ss; | |
5496 | int i, j, ret; | |
5497 | ||
5498 | for_each_subsys_which(ss, i, &have_canfork_callback) { | |
5499 | ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i)); | |
5500 | if (ret) | |
5501 | goto out_revert; | |
5502 | } | |
5503 | ||
5504 | return 0; | |
5505 | ||
5506 | out_revert: | |
5507 | for_each_subsys(ss, j) { | |
5508 | if (j >= i) | |
5509 | break; | |
5510 | if (ss->cancel_fork) | |
5511 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j)); | |
5512 | } | |
5513 | ||
5514 | return ret; | |
5515 | } | |
5516 | ||
5517 | /** | |
5518 | * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() | |
5519 | * @child: the task in question | |
5520 | * | |
5521 | * This calls the cancel_fork() callbacks if a fork failed *after* | |
5522 | * cgroup_can_fork() succeded. | |
5523 | */ | |
5524 | void cgroup_cancel_fork(struct task_struct *child, | |
5525 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5526 | { | |
5527 | struct cgroup_subsys *ss; | |
5528 | int i; | |
5529 | ||
5530 | for_each_subsys(ss, i) | |
5531 | if (ss->cancel_fork) | |
5532 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i)); | |
5533 | } | |
5534 | ||
817929ec | 5535 | /** |
a043e3b2 LZ |
5536 | * cgroup_post_fork - called on a new task after adding it to the task list |
5537 | * @child: the task in question | |
5538 | * | |
5edee61e TH |
5539 | * Adds the task to the list running through its css_set if necessary and |
5540 | * call the subsystem fork() callbacks. Has to be after the task is | |
5541 | * visible on the task list in case we race with the first call to | |
0942eeee | 5542 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 5543 | * list. |
a043e3b2 | 5544 | */ |
7e47682e AS |
5545 | void cgroup_post_fork(struct task_struct *child, |
5546 | void *old_ss_priv[CGROUP_CANFORK_COUNT]) | |
817929ec | 5547 | { |
30159ec7 | 5548 | struct cgroup_subsys *ss; |
5edee61e TH |
5549 | int i; |
5550 | ||
3ce3230a | 5551 | /* |
251f8c03 | 5552 | * This may race against cgroup_enable_task_cg_lists(). As that |
eaf797ab TH |
5553 | * function sets use_task_css_set_links before grabbing |
5554 | * tasklist_lock and we just went through tasklist_lock to add | |
5555 | * @child, it's guaranteed that either we see the set | |
5556 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
5557 | * @child during its iteration. | |
5558 | * | |
5559 | * If we won the race, @child is associated with %current's | |
f0d9a5f1 | 5560 | * css_set. Grabbing css_set_lock guarantees both that the |
eaf797ab TH |
5561 | * association is stable, and, on completion of the parent's |
5562 | * migration, @child is visible in the source of migration or | |
5563 | * already in the destination cgroup. This guarantee is necessary | |
5564 | * when implementing operations which need to migrate all tasks of | |
5565 | * a cgroup to another. | |
5566 | * | |
251f8c03 | 5567 | * Note that if we lose to cgroup_enable_task_cg_lists(), @child |
eaf797ab TH |
5568 | * will remain in init_css_set. This is safe because all tasks are |
5569 | * in the init_css_set before cg_links is enabled and there's no | |
5570 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 5571 | */ |
817929ec | 5572 | if (use_task_css_set_links) { |
eaf797ab TH |
5573 | struct css_set *cset; |
5574 | ||
f0d9a5f1 | 5575 | spin_lock_bh(&css_set_lock); |
0e1d768f | 5576 | cset = task_css_set(current); |
eaf797ab | 5577 | if (list_empty(&child->cg_list)) { |
eaf797ab | 5578 | get_css_set(cset); |
f6d7d049 | 5579 | css_set_move_task(child, NULL, cset, false); |
eaf797ab | 5580 | } |
f0d9a5f1 | 5581 | spin_unlock_bh(&css_set_lock); |
817929ec | 5582 | } |
5edee61e TH |
5583 | |
5584 | /* | |
5585 | * Call ss->fork(). This must happen after @child is linked on | |
5586 | * css_set; otherwise, @child might change state between ->fork() | |
5587 | * and addition to css_set. | |
5588 | */ | |
cb4a3167 | 5589 | for_each_subsys_which(ss, i, &have_fork_callback) |
7e47682e | 5590 | ss->fork(child, subsys_canfork_priv(old_ss_priv, i)); |
817929ec | 5591 | } |
5edee61e | 5592 | |
b4f48b63 PM |
5593 | /** |
5594 | * cgroup_exit - detach cgroup from exiting task | |
5595 | * @tsk: pointer to task_struct of exiting process | |
5596 | * | |
5597 | * Description: Detach cgroup from @tsk and release it. | |
5598 | * | |
5599 | * Note that cgroups marked notify_on_release force every task in | |
5600 | * them to take the global cgroup_mutex mutex when exiting. | |
5601 | * This could impact scaling on very large systems. Be reluctant to | |
5602 | * use notify_on_release cgroups where very high task exit scaling | |
5603 | * is required on large systems. | |
5604 | * | |
0e1d768f TH |
5605 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
5606 | * call cgroup_exit() while the task is still competent to handle | |
5607 | * notify_on_release(), then leave the task attached to the root cgroup in | |
5608 | * each hierarchy for the remainder of its exit. No need to bother with | |
5609 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 5610 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 5611 | */ |
1ec41830 | 5612 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 5613 | { |
30159ec7 | 5614 | struct cgroup_subsys *ss; |
5abb8855 | 5615 | struct css_set *cset; |
d41d5a01 | 5616 | int i; |
817929ec PM |
5617 | |
5618 | /* | |
0e1d768f | 5619 | * Unlink from @tsk from its css_set. As migration path can't race |
0de0942d | 5620 | * with us, we can check css_set and cg_list without synchronization. |
817929ec | 5621 | */ |
0de0942d TH |
5622 | cset = task_css_set(tsk); |
5623 | ||
817929ec | 5624 | if (!list_empty(&tsk->cg_list)) { |
f0d9a5f1 | 5625 | spin_lock_bh(&css_set_lock); |
f6d7d049 | 5626 | css_set_move_task(tsk, cset, NULL, false); |
f0d9a5f1 | 5627 | spin_unlock_bh(&css_set_lock); |
2e91fa7f TH |
5628 | } else { |
5629 | get_css_set(cset); | |
817929ec PM |
5630 | } |
5631 | ||
cb4a3167 | 5632 | /* see cgroup_post_fork() for details */ |
2e91fa7f TH |
5633 | for_each_subsys_which(ss, i, &have_exit_callback) |
5634 | ss->exit(tsk); | |
5635 | } | |
30159ec7 | 5636 | |
2e91fa7f TH |
5637 | void cgroup_free(struct task_struct *task) |
5638 | { | |
5639 | struct css_set *cset = task_css_set(task); | |
d41d5a01 | 5640 | |
2e91fa7f | 5641 | put_css_set(cset); |
b4f48b63 | 5642 | } |
697f4161 | 5643 | |
bd89aabc | 5644 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5645 | { |
27bd4dbb | 5646 | if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) && |
971ff493 ZL |
5647 | !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
5648 | schedule_work(&cgrp->release_agent_work); | |
81a6a5cd PM |
5649 | } |
5650 | ||
81a6a5cd PM |
5651 | /* |
5652 | * Notify userspace when a cgroup is released, by running the | |
5653 | * configured release agent with the name of the cgroup (path | |
5654 | * relative to the root of cgroup file system) as the argument. | |
5655 | * | |
5656 | * Most likely, this user command will try to rmdir this cgroup. | |
5657 | * | |
5658 | * This races with the possibility that some other task will be | |
5659 | * attached to this cgroup before it is removed, or that some other | |
5660 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5661 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5662 | * unused, and this cgroup will be reprieved from its death sentence, | |
5663 | * to continue to serve a useful existence. Next time it's released, | |
5664 | * we will get notified again, if it still has 'notify_on_release' set. | |
5665 | * | |
5666 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5667 | * means only wait until the task is successfully execve()'d. The | |
5668 | * separate release agent task is forked by call_usermodehelper(), | |
5669 | * then control in this thread returns here, without waiting for the | |
5670 | * release agent task. We don't bother to wait because the caller of | |
5671 | * this routine has no use for the exit status of the release agent | |
5672 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5673 | */ |
81a6a5cd PM |
5674 | static void cgroup_release_agent(struct work_struct *work) |
5675 | { | |
971ff493 ZL |
5676 | struct cgroup *cgrp = |
5677 | container_of(work, struct cgroup, release_agent_work); | |
5678 | char *pathbuf = NULL, *agentbuf = NULL, *path; | |
5679 | char *argv[3], *envp[3]; | |
5680 | ||
81a6a5cd | 5681 | mutex_lock(&cgroup_mutex); |
971ff493 ZL |
5682 | |
5683 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); | |
5684 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5685 | if (!pathbuf || !agentbuf) | |
5686 | goto out; | |
5687 | ||
5688 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); | |
5689 | if (!path) | |
5690 | goto out; | |
5691 | ||
5692 | argv[0] = agentbuf; | |
5693 | argv[1] = path; | |
5694 | argv[2] = NULL; | |
5695 | ||
5696 | /* minimal command environment */ | |
5697 | envp[0] = "HOME=/"; | |
5698 | envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5699 | envp[2] = NULL; | |
5700 | ||
81a6a5cd | 5701 | mutex_unlock(&cgroup_mutex); |
971ff493 | 5702 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
3e2cd91a | 5703 | goto out_free; |
971ff493 | 5704 | out: |
81a6a5cd | 5705 | mutex_unlock(&cgroup_mutex); |
3e2cd91a | 5706 | out_free: |
971ff493 ZL |
5707 | kfree(agentbuf); |
5708 | kfree(pathbuf); | |
81a6a5cd | 5709 | } |
8bab8dde PM |
5710 | |
5711 | static int __init cgroup_disable(char *str) | |
5712 | { | |
30159ec7 | 5713 | struct cgroup_subsys *ss; |
8bab8dde | 5714 | char *token; |
30159ec7 | 5715 | int i; |
8bab8dde PM |
5716 | |
5717 | while ((token = strsep(&str, ",")) != NULL) { | |
5718 | if (!*token) | |
5719 | continue; | |
be45c900 | 5720 | |
3ed80a62 | 5721 | for_each_subsys(ss, i) { |
3e1d2eed TH |
5722 | if (strcmp(token, ss->name) && |
5723 | strcmp(token, ss->legacy_name)) | |
5724 | continue; | |
a3e72739 | 5725 | cgroup_disable_mask |= 1 << i; |
8bab8dde PM |
5726 | } |
5727 | } | |
5728 | return 1; | |
5729 | } | |
5730 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 5731 | |
a8ddc821 TH |
5732 | static int __init cgroup_set_legacy_files_on_dfl(char *str) |
5733 | { | |
5734 | printk("cgroup: using legacy files on the default hierarchy\n"); | |
5735 | cgroup_legacy_files_on_dfl = true; | |
5736 | return 0; | |
5737 | } | |
5738 | __setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl); | |
5739 | ||
b77d7b60 | 5740 | /** |
ec903c0c | 5741 | * css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
35cf0836 TH |
5742 | * @dentry: directory dentry of interest |
5743 | * @ss: subsystem of interest | |
b77d7b60 | 5744 | * |
5a17f543 TH |
5745 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
5746 | * to get the corresponding css and return it. If such css doesn't exist | |
5747 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 5748 | */ |
ec903c0c TH |
5749 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
5750 | struct cgroup_subsys *ss) | |
e5d1367f | 5751 | { |
2bd59d48 TH |
5752 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
5753 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 5754 | struct cgroup *cgrp; |
e5d1367f | 5755 | |
35cf0836 | 5756 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
5757 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
5758 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
5759 | return ERR_PTR(-EBADF); |
5760 | ||
5a17f543 TH |
5761 | rcu_read_lock(); |
5762 | ||
2bd59d48 TH |
5763 | /* |
5764 | * This path doesn't originate from kernfs and @kn could already | |
5765 | * have been or be removed at any point. @kn->priv is RCU | |
a4189487 | 5766 | * protected for this access. See css_release_work_fn() for details. |
2bd59d48 TH |
5767 | */ |
5768 | cgrp = rcu_dereference(kn->priv); | |
5769 | if (cgrp) | |
5770 | css = cgroup_css(cgrp, ss); | |
5a17f543 | 5771 | |
ec903c0c | 5772 | if (!css || !css_tryget_online(css)) |
5a17f543 TH |
5773 | css = ERR_PTR(-ENOENT); |
5774 | ||
5775 | rcu_read_unlock(); | |
5776 | return css; | |
e5d1367f | 5777 | } |
e5d1367f | 5778 | |
1cb650b9 LZ |
5779 | /** |
5780 | * css_from_id - lookup css by id | |
5781 | * @id: the cgroup id | |
5782 | * @ss: cgroup subsys to be looked into | |
5783 | * | |
5784 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
5785 | * Should be called under rcu_read_lock(). | |
5786 | */ | |
5787 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
5788 | { | |
6fa4918d | 5789 | WARN_ON_ONCE(!rcu_read_lock_held()); |
adbe427b | 5790 | return id > 0 ? idr_find(&ss->css_idr, id) : NULL; |
e5d1367f SE |
5791 | } |
5792 | ||
fe693435 | 5793 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
5794 | static struct cgroup_subsys_state * |
5795 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
5796 | { |
5797 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5798 | ||
5799 | if (!css) | |
5800 | return ERR_PTR(-ENOMEM); | |
5801 | ||
5802 | return css; | |
5803 | } | |
5804 | ||
eb95419b | 5805 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 5806 | { |
eb95419b | 5807 | kfree(css); |
fe693435 PM |
5808 | } |
5809 | ||
182446d0 TH |
5810 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
5811 | struct cftype *cft) | |
fe693435 | 5812 | { |
182446d0 | 5813 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
5814 | } |
5815 | ||
182446d0 TH |
5816 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
5817 | struct cftype *cft) | |
fe693435 PM |
5818 | { |
5819 | return (u64)(unsigned long)current->cgroups; | |
5820 | } | |
5821 | ||
182446d0 | 5822 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 5823 | struct cftype *cft) |
fe693435 PM |
5824 | { |
5825 | u64 count; | |
5826 | ||
5827 | rcu_read_lock(); | |
a8ad805c | 5828 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
5829 | rcu_read_unlock(); |
5830 | return count; | |
5831 | } | |
5832 | ||
2da8ca82 | 5833 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5834 | { |
69d0206c | 5835 | struct cgrp_cset_link *link; |
5abb8855 | 5836 | struct css_set *cset; |
e61734c5 TH |
5837 | char *name_buf; |
5838 | ||
5839 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
5840 | if (!name_buf) | |
5841 | return -ENOMEM; | |
7717f7ba | 5842 | |
f0d9a5f1 | 5843 | spin_lock_bh(&css_set_lock); |
7717f7ba | 5844 | rcu_read_lock(); |
5abb8855 | 5845 | cset = rcu_dereference(current->cgroups); |
69d0206c | 5846 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 5847 | struct cgroup *c = link->cgrp; |
7717f7ba | 5848 | |
a2dd4247 | 5849 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 5850 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 5851 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
5852 | } |
5853 | rcu_read_unlock(); | |
f0d9a5f1 | 5854 | spin_unlock_bh(&css_set_lock); |
e61734c5 | 5855 | kfree(name_buf); |
7717f7ba PM |
5856 | return 0; |
5857 | } | |
5858 | ||
5859 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 5860 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5861 | { |
2da8ca82 | 5862 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 5863 | struct cgrp_cset_link *link; |
7717f7ba | 5864 | |
f0d9a5f1 | 5865 | spin_lock_bh(&css_set_lock); |
182446d0 | 5866 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 5867 | struct css_set *cset = link->cset; |
7717f7ba PM |
5868 | struct task_struct *task; |
5869 | int count = 0; | |
c7561128 | 5870 | |
5abb8855 | 5871 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 5872 | |
5abb8855 | 5873 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
5874 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
5875 | goto overflow; | |
5876 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
5877 | } | |
5878 | ||
5879 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
5880 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
5881 | goto overflow; | |
5882 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 5883 | } |
c7561128 TH |
5884 | continue; |
5885 | overflow: | |
5886 | seq_puts(seq, " ...\n"); | |
7717f7ba | 5887 | } |
f0d9a5f1 | 5888 | spin_unlock_bh(&css_set_lock); |
7717f7ba PM |
5889 | return 0; |
5890 | } | |
5891 | ||
182446d0 | 5892 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 5893 | { |
27bd4dbb | 5894 | return (!cgroup_is_populated(css->cgroup) && |
a25eb52e | 5895 | !css_has_online_children(&css->cgroup->self)); |
fe693435 PM |
5896 | } |
5897 | ||
5898 | static struct cftype debug_files[] = { | |
fe693435 PM |
5899 | { |
5900 | .name = "taskcount", | |
5901 | .read_u64 = debug_taskcount_read, | |
5902 | }, | |
5903 | ||
5904 | { | |
5905 | .name = "current_css_set", | |
5906 | .read_u64 = current_css_set_read, | |
5907 | }, | |
5908 | ||
5909 | { | |
5910 | .name = "current_css_set_refcount", | |
5911 | .read_u64 = current_css_set_refcount_read, | |
5912 | }, | |
5913 | ||
7717f7ba PM |
5914 | { |
5915 | .name = "current_css_set_cg_links", | |
2da8ca82 | 5916 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
5917 | }, |
5918 | ||
5919 | { | |
5920 | .name = "cgroup_css_links", | |
2da8ca82 | 5921 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
5922 | }, |
5923 | ||
fe693435 PM |
5924 | { |
5925 | .name = "releasable", | |
5926 | .read_u64 = releasable_read, | |
5927 | }, | |
fe693435 | 5928 | |
4baf6e33 TH |
5929 | { } /* terminate */ |
5930 | }; | |
fe693435 | 5931 | |
073219e9 | 5932 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
5933 | .css_alloc = debug_css_alloc, |
5934 | .css_free = debug_css_free, | |
5577964e | 5935 | .legacy_cftypes = debug_files, |
fe693435 PM |
5936 | }; |
5937 | #endif /* CONFIG_CGROUP_DEBUG */ |