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> |
96d365e0 | 48 | #include <linux/rwsem.h> |
1ed13287 | 49 | #include <linux/percpu-rwsem.h> |
ddbcc7e8 | 50 | #include <linux/string.h> |
bbcb81d0 | 51 | #include <linux/sort.h> |
81a6a5cd | 52 | #include <linux/kmod.h> |
846c7bb0 BS |
53 | #include <linux/delayacct.h> |
54 | #include <linux/cgroupstats.h> | |
0ac801fe | 55 | #include <linux/hashtable.h> |
096b7fe0 | 56 | #include <linux/pid_namespace.h> |
2c6ab6d2 | 57 | #include <linux/idr.h> |
d1d9fd33 | 58 | #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
c4c27fbd | 59 | #include <linux/kthread.h> |
776f02fa | 60 | #include <linux/delay.h> |
846c7bb0 | 61 | |
60063497 | 62 | #include <linux/atomic.h> |
ddbcc7e8 | 63 | |
b1a21367 TH |
64 | /* |
65 | * pidlists linger the following amount before being destroyed. The goal | |
66 | * is avoiding frequent destruction in the middle of consecutive read calls | |
67 | * Expiring in the middle is a performance problem not a correctness one. | |
68 | * 1 sec should be enough. | |
69 | */ | |
70 | #define CGROUP_PIDLIST_DESTROY_DELAY HZ | |
71 | ||
8d7e6fb0 TH |
72 | #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
73 | MAX_CFTYPE_NAME + 2) | |
74 | ||
e25e2cbb TH |
75 | /* |
76 | * cgroup_mutex is the master lock. Any modification to cgroup or its | |
77 | * hierarchy must be performed while holding it. | |
78 | * | |
0e1d768f TH |
79 | * css_set_rwsem protects task->cgroups pointer, the list of css_set |
80 | * objects, and the chain of tasks off each css_set. | |
e25e2cbb | 81 | * |
0e1d768f TH |
82 | * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
83 | * cgroup.h can use them for lockdep annotations. | |
e25e2cbb | 84 | */ |
2219449a TH |
85 | #ifdef CONFIG_PROVE_RCU |
86 | DEFINE_MUTEX(cgroup_mutex); | |
0e1d768f TH |
87 | DECLARE_RWSEM(css_set_rwsem); |
88 | EXPORT_SYMBOL_GPL(cgroup_mutex); | |
89 | EXPORT_SYMBOL_GPL(css_set_rwsem); | |
2219449a | 90 | #else |
81a6a5cd | 91 | static DEFINE_MUTEX(cgroup_mutex); |
0e1d768f | 92 | static DECLARE_RWSEM(css_set_rwsem); |
2219449a TH |
93 | #endif |
94 | ||
6fa4918d | 95 | /* |
15a4c835 TH |
96 | * Protects cgroup_idr and css_idr so that IDs can be released without |
97 | * grabbing cgroup_mutex. | |
6fa4918d TH |
98 | */ |
99 | static DEFINE_SPINLOCK(cgroup_idr_lock); | |
100 | ||
69e943b7 TH |
101 | /* |
102 | * Protects cgroup_subsys->release_agent_path. Modifying it also requires | |
103 | * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. | |
104 | */ | |
105 | static DEFINE_SPINLOCK(release_agent_path_lock); | |
81a6a5cd | 106 | |
1ed13287 TH |
107 | struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
108 | ||
8353da1f | 109 | #define cgroup_assert_mutex_or_rcu_locked() \ |
f78f5b90 PM |
110 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
111 | !lockdep_is_held(&cgroup_mutex), \ | |
8353da1f | 112 | "cgroup_mutex or RCU read lock required"); |
780cd8b3 | 113 | |
e5fca243 TH |
114 | /* |
115 | * cgroup destruction makes heavy use of work items and there can be a lot | |
116 | * of concurrent destructions. Use a separate workqueue so that cgroup | |
117 | * destruction work items don't end up filling up max_active of system_wq | |
118 | * which may lead to deadlock. | |
119 | */ | |
120 | static struct workqueue_struct *cgroup_destroy_wq; | |
121 | ||
b1a21367 TH |
122 | /* |
123 | * pidlist destructions need to be flushed on cgroup destruction. Use a | |
124 | * separate workqueue as flush domain. | |
125 | */ | |
126 | static struct workqueue_struct *cgroup_pidlist_destroy_wq; | |
127 | ||
3ed80a62 | 128 | /* generate an array of cgroup subsystem pointers */ |
073219e9 | 129 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
3ed80a62 | 130 | static struct cgroup_subsys *cgroup_subsys[] = { |
ddbcc7e8 PM |
131 | #include <linux/cgroup_subsys.h> |
132 | }; | |
073219e9 TH |
133 | #undef SUBSYS |
134 | ||
135 | /* array of cgroup subsystem names */ | |
136 | #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, | |
137 | static const char *cgroup_subsys_name[] = { | |
ddbcc7e8 PM |
138 | #include <linux/cgroup_subsys.h> |
139 | }; | |
073219e9 | 140 | #undef SUBSYS |
ddbcc7e8 | 141 | |
49d1dc4b TH |
142 | /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
143 | #define SUBSYS(_x) \ | |
144 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ | |
145 | DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ | |
146 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ | |
147 | EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); | |
148 | #include <linux/cgroup_subsys.h> | |
149 | #undef SUBSYS | |
150 | ||
151 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, | |
152 | static struct static_key_true *cgroup_subsys_enabled_key[] = { | |
153 | #include <linux/cgroup_subsys.h> | |
154 | }; | |
155 | #undef SUBSYS | |
156 | ||
157 | #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, | |
158 | static struct static_key_true *cgroup_subsys_on_dfl_key[] = { | |
159 | #include <linux/cgroup_subsys.h> | |
160 | }; | |
161 | #undef SUBSYS | |
162 | ||
ddbcc7e8 | 163 | /* |
3dd06ffa | 164 | * The default hierarchy, reserved for the subsystems that are otherwise |
9871bf95 TH |
165 | * unattached - it never has more than a single cgroup, and all tasks are |
166 | * part of that cgroup. | |
ddbcc7e8 | 167 | */ |
a2dd4247 | 168 | struct cgroup_root cgrp_dfl_root; |
d0ec4230 | 169 | EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
9871bf95 | 170 | |
a2dd4247 TH |
171 | /* |
172 | * The default hierarchy always exists but is hidden until mounted for the | |
173 | * first time. This is for backward compatibility. | |
174 | */ | |
175 | static bool cgrp_dfl_root_visible; | |
ddbcc7e8 | 176 | |
a8ddc821 TH |
177 | /* |
178 | * Set by the boot param of the same name and makes subsystems with NULL | |
179 | * ->dfl_files to use ->legacy_files on the default hierarchy. | |
180 | */ | |
181 | static bool cgroup_legacy_files_on_dfl; | |
182 | ||
5533e011 | 183 | /* some controllers are not supported in the default hierarchy */ |
8ab456ac | 184 | static unsigned long cgrp_dfl_root_inhibit_ss_mask; |
5533e011 | 185 | |
ddbcc7e8 PM |
186 | /* The list of hierarchy roots */ |
187 | ||
9871bf95 TH |
188 | static LIST_HEAD(cgroup_roots); |
189 | static int cgroup_root_count; | |
ddbcc7e8 | 190 | |
3417ae1f | 191 | /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
1a574231 | 192 | static DEFINE_IDR(cgroup_hierarchy_idr); |
2c6ab6d2 | 193 | |
794611a1 | 194 | /* |
0cb51d71 TH |
195 | * Assign a monotonically increasing serial number to csses. It guarantees |
196 | * cgroups with bigger numbers are newer than those with smaller numbers. | |
197 | * Also, as csses are always appended to the parent's ->children list, it | |
198 | * guarantees that sibling csses are always sorted in the ascending serial | |
199 | * number order on the list. Protected by cgroup_mutex. | |
794611a1 | 200 | */ |
0cb51d71 | 201 | static u64 css_serial_nr_next = 1; |
794611a1 | 202 | |
cb4a3167 AS |
203 | /* |
204 | * These bitmask flags indicate whether tasks in the fork and exit paths have | |
205 | * fork/exit handlers to call. This avoids us having to do extra work in the | |
206 | * fork/exit path to check which subsystems have fork/exit callbacks. | |
ddbcc7e8 | 207 | */ |
cb4a3167 AS |
208 | static unsigned long have_fork_callback __read_mostly; |
209 | static unsigned long have_exit_callback __read_mostly; | |
ddbcc7e8 | 210 | |
7e47682e AS |
211 | /* Ditto for the can_fork callback. */ |
212 | static unsigned long have_canfork_callback __read_mostly; | |
213 | ||
a14c6874 TH |
214 | static struct cftype cgroup_dfl_base_files[]; |
215 | static struct cftype cgroup_legacy_base_files[]; | |
628f7cd4 | 216 | |
3dd06ffa | 217 | static int rebind_subsystems(struct cgroup_root *dst_root, |
8ab456ac | 218 | unsigned long ss_mask); |
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); |
2bb566cb TH |
224 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
225 | bool is_add); | |
42809dd4 | 226 | |
fc5ed1e9 TH |
227 | /** |
228 | * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID | |
229 | * @ssid: subsys ID of interest | |
230 | * | |
231 | * cgroup_subsys_enabled() can only be used with literal subsys names which | |
232 | * is fine for individual subsystems but unsuitable for cgroup core. This | |
233 | * is slower static_key_enabled() based test indexed by @ssid. | |
234 | */ | |
235 | static bool cgroup_ssid_enabled(int ssid) | |
236 | { | |
237 | return static_key_enabled(cgroup_subsys_enabled_key[ssid]); | |
238 | } | |
239 | ||
9e10a130 TH |
240 | /** |
241 | * cgroup_on_dfl - test whether a cgroup is on the default hierarchy | |
242 | * @cgrp: the cgroup of interest | |
243 | * | |
244 | * The default hierarchy is the v2 interface of cgroup and this function | |
245 | * can be used to test whether a cgroup is on the default hierarchy for | |
246 | * cases where a subsystem should behave differnetly depending on the | |
247 | * interface version. | |
248 | * | |
249 | * The set of behaviors which change on the default hierarchy are still | |
250 | * being determined and the mount option is prefixed with __DEVEL__. | |
251 | * | |
252 | * List of changed behaviors: | |
253 | * | |
254 | * - Mount options "noprefix", "xattr", "clone_children", "release_agent" | |
255 | * and "name" are disallowed. | |
256 | * | |
257 | * - When mounting an existing superblock, mount options should match. | |
258 | * | |
259 | * - Remount is disallowed. | |
260 | * | |
261 | * - rename(2) is disallowed. | |
262 | * | |
263 | * - "tasks" is removed. Everything should be at process granularity. Use | |
264 | * "cgroup.procs" instead. | |
265 | * | |
266 | * - "cgroup.procs" is not sorted. pids will be unique unless they got | |
267 | * recycled inbetween reads. | |
268 | * | |
269 | * - "release_agent" and "notify_on_release" are removed. Replacement | |
270 | * notification mechanism will be implemented. | |
271 | * | |
272 | * - "cgroup.clone_children" is removed. | |
273 | * | |
274 | * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup | |
275 | * and its descendants contain no task; otherwise, 1. The file also | |
276 | * generates kernfs notification which can be monitored through poll and | |
277 | * [di]notify when the value of the file changes. | |
278 | * | |
279 | * - cpuset: tasks will be kept in empty cpusets when hotplug happens and | |
280 | * take masks of ancestors with non-empty cpus/mems, instead of being | |
281 | * moved to an ancestor. | |
282 | * | |
283 | * - cpuset: a task can be moved into an empty cpuset, and again it takes | |
284 | * masks of ancestors. | |
285 | * | |
286 | * - memcg: use_hierarchy is on by default and the cgroup file for the flag | |
287 | * is not created. | |
288 | * | |
289 | * - blkcg: blk-throttle becomes properly hierarchical. | |
290 | * | |
291 | * - debug: disallowed on the default hierarchy. | |
292 | */ | |
293 | static bool cgroup_on_dfl(const struct cgroup *cgrp) | |
294 | { | |
295 | return cgrp->root == &cgrp_dfl_root; | |
296 | } | |
297 | ||
6fa4918d TH |
298 | /* IDR wrappers which synchronize using cgroup_idr_lock */ |
299 | static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, | |
300 | gfp_t gfp_mask) | |
301 | { | |
302 | int ret; | |
303 | ||
304 | idr_preload(gfp_mask); | |
54504e97 | 305 | spin_lock_bh(&cgroup_idr_lock); |
cf780b7d | 306 | ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_WAIT); |
54504e97 | 307 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
308 | idr_preload_end(); |
309 | return ret; | |
310 | } | |
311 | ||
312 | static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) | |
313 | { | |
314 | void *ret; | |
315 | ||
54504e97 | 316 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 317 | ret = idr_replace(idr, ptr, id); |
54504e97 | 318 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
319 | return ret; |
320 | } | |
321 | ||
322 | static void cgroup_idr_remove(struct idr *idr, int id) | |
323 | { | |
54504e97 | 324 | spin_lock_bh(&cgroup_idr_lock); |
6fa4918d | 325 | idr_remove(idr, id); |
54504e97 | 326 | spin_unlock_bh(&cgroup_idr_lock); |
6fa4918d TH |
327 | } |
328 | ||
d51f39b0 TH |
329 | static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
330 | { | |
331 | struct cgroup_subsys_state *parent_css = cgrp->self.parent; | |
332 | ||
333 | if (parent_css) | |
334 | return container_of(parent_css, struct cgroup, self); | |
335 | return NULL; | |
336 | } | |
337 | ||
95109b62 TH |
338 | /** |
339 | * cgroup_css - obtain a cgroup's css for the specified subsystem | |
340 | * @cgrp: the cgroup of interest | |
9d800df1 | 341 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
95109b62 | 342 | * |
ca8bdcaf TH |
343 | * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
344 | * function must be called either under cgroup_mutex or rcu_read_lock() and | |
345 | * the caller is responsible for pinning the returned css if it wants to | |
346 | * keep accessing it outside the said locks. This function may return | |
347 | * %NULL if @cgrp doesn't have @subsys_id enabled. | |
95109b62 TH |
348 | */ |
349 | static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, | |
ca8bdcaf | 350 | struct cgroup_subsys *ss) |
95109b62 | 351 | { |
ca8bdcaf | 352 | if (ss) |
aec25020 | 353 | return rcu_dereference_check(cgrp->subsys[ss->id], |
ace2bee8 | 354 | lockdep_is_held(&cgroup_mutex)); |
ca8bdcaf | 355 | else |
9d800df1 | 356 | return &cgrp->self; |
95109b62 | 357 | } |
42809dd4 | 358 | |
aec3dfcb TH |
359 | /** |
360 | * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem | |
361 | * @cgrp: the cgroup of interest | |
9d800df1 | 362 | * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
aec3dfcb | 363 | * |
d0f702e6 | 364 | * Similar to cgroup_css() but returns the effective css, which is defined |
aec3dfcb TH |
365 | * as the matching css of the nearest ancestor including self which has @ss |
366 | * enabled. If @ss is associated with the hierarchy @cgrp is on, this | |
367 | * function is guaranteed to return non-NULL css. | |
368 | */ | |
369 | static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, | |
370 | struct cgroup_subsys *ss) | |
371 | { | |
372 | lockdep_assert_held(&cgroup_mutex); | |
373 | ||
374 | if (!ss) | |
9d800df1 | 375 | return &cgrp->self; |
aec3dfcb TH |
376 | |
377 | if (!(cgrp->root->subsys_mask & (1 << ss->id))) | |
378 | return NULL; | |
379 | ||
eeecbd19 TH |
380 | /* |
381 | * This function is used while updating css associations and thus | |
382 | * can't test the csses directly. Use ->child_subsys_mask. | |
383 | */ | |
d51f39b0 TH |
384 | while (cgroup_parent(cgrp) && |
385 | !(cgroup_parent(cgrp)->child_subsys_mask & (1 << ss->id))) | |
386 | cgrp = cgroup_parent(cgrp); | |
aec3dfcb TH |
387 | |
388 | return cgroup_css(cgrp, ss); | |
95109b62 | 389 | } |
42809dd4 | 390 | |
eeecbd19 TH |
391 | /** |
392 | * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem | |
393 | * @cgrp: the cgroup of interest | |
394 | * @ss: the subsystem of interest | |
395 | * | |
396 | * Find and get the effective css of @cgrp for @ss. The effective css is | |
397 | * defined as the matching css of the nearest ancestor including self which | |
398 | * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, | |
399 | * the root css is returned, so this function always returns a valid css. | |
400 | * The returned css must be put using css_put(). | |
401 | */ | |
402 | struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, | |
403 | struct cgroup_subsys *ss) | |
404 | { | |
405 | struct cgroup_subsys_state *css; | |
406 | ||
407 | rcu_read_lock(); | |
408 | ||
409 | do { | |
410 | css = cgroup_css(cgrp, ss); | |
411 | ||
412 | if (css && css_tryget_online(css)) | |
413 | goto out_unlock; | |
414 | cgrp = cgroup_parent(cgrp); | |
415 | } while (cgrp); | |
416 | ||
417 | css = init_css_set.subsys[ss->id]; | |
418 | css_get(css); | |
419 | out_unlock: | |
420 | rcu_read_unlock(); | |
421 | return css; | |
422 | } | |
423 | ||
ddbcc7e8 | 424 | /* convenient tests for these bits */ |
54766d4a | 425 | static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
ddbcc7e8 | 426 | { |
184faf32 | 427 | return !(cgrp->self.flags & CSS_ONLINE); |
ddbcc7e8 PM |
428 | } |
429 | ||
b4168640 | 430 | struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
59f5296b | 431 | { |
2bd59d48 | 432 | struct cgroup *cgrp = of->kn->parent->priv; |
b4168640 | 433 | struct cftype *cft = of_cft(of); |
2bd59d48 TH |
434 | |
435 | /* | |
436 | * This is open and unprotected implementation of cgroup_css(). | |
437 | * seq_css() is only called from a kernfs file operation which has | |
438 | * an active reference on the file. Because all the subsystem | |
439 | * files are drained before a css is disassociated with a cgroup, | |
440 | * the matching css from the cgroup's subsys table is guaranteed to | |
441 | * be and stay valid until the enclosing operation is complete. | |
442 | */ | |
443 | if (cft->ss) | |
444 | return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); | |
445 | else | |
9d800df1 | 446 | return &cgrp->self; |
59f5296b | 447 | } |
b4168640 | 448 | EXPORT_SYMBOL_GPL(of_css); |
59f5296b | 449 | |
78574cf9 LZ |
450 | /** |
451 | * cgroup_is_descendant - test ancestry | |
452 | * @cgrp: the cgroup to be tested | |
453 | * @ancestor: possible ancestor of @cgrp | |
454 | * | |
455 | * Test whether @cgrp is a descendant of @ancestor. It also returns %true | |
456 | * if @cgrp == @ancestor. This function is safe to call as long as @cgrp | |
457 | * and @ancestor are accessible. | |
458 | */ | |
459 | bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor) | |
460 | { | |
461 | while (cgrp) { | |
462 | if (cgrp == ancestor) | |
463 | return true; | |
d51f39b0 | 464 | cgrp = cgroup_parent(cgrp); |
78574cf9 LZ |
465 | } |
466 | return false; | |
467 | } | |
ddbcc7e8 | 468 | |
e9685a03 | 469 | static int notify_on_release(const struct cgroup *cgrp) |
81a6a5cd | 470 | { |
bd89aabc | 471 | return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
81a6a5cd PM |
472 | } |
473 | ||
1c6727af TH |
474 | /** |
475 | * for_each_css - iterate all css's of a cgroup | |
476 | * @css: the iteration cursor | |
477 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
478 | * @cgrp: the target cgroup to iterate css's of | |
479 | * | |
aec3dfcb | 480 | * Should be called under cgroup_[tree_]mutex. |
1c6727af TH |
481 | */ |
482 | #define for_each_css(css, ssid, cgrp) \ | |
483 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
484 | if (!((css) = rcu_dereference_check( \ | |
485 | (cgrp)->subsys[(ssid)], \ | |
486 | lockdep_is_held(&cgroup_mutex)))) { } \ | |
487 | else | |
488 | ||
aec3dfcb TH |
489 | /** |
490 | * for_each_e_css - iterate all effective css's of a cgroup | |
491 | * @css: the iteration cursor | |
492 | * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end | |
493 | * @cgrp: the target cgroup to iterate css's of | |
494 | * | |
495 | * Should be called under cgroup_[tree_]mutex. | |
496 | */ | |
497 | #define for_each_e_css(css, ssid, cgrp) \ | |
498 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ | |
499 | if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \ | |
500 | ; \ | |
501 | else | |
502 | ||
30159ec7 | 503 | /** |
3ed80a62 | 504 | * for_each_subsys - iterate all enabled cgroup subsystems |
30159ec7 | 505 | * @ss: the iteration cursor |
780cd8b3 | 506 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
30159ec7 | 507 | */ |
780cd8b3 | 508 | #define for_each_subsys(ss, ssid) \ |
3ed80a62 TH |
509 | for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
510 | (((ss) = cgroup_subsys[ssid]) || true); (ssid)++) | |
30159ec7 | 511 | |
cb4a3167 AS |
512 | /** |
513 | * for_each_subsys_which - filter for_each_subsys with a bitmask | |
514 | * @ss: the iteration cursor | |
515 | * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end | |
516 | * @ss_maskp: a pointer to the bitmask | |
517 | * | |
518 | * The block will only run for cases where the ssid-th bit (1 << ssid) of | |
519 | * mask is set to 1. | |
520 | */ | |
521 | #define for_each_subsys_which(ss, ssid, ss_maskp) \ | |
522 | if (!CGROUP_SUBSYS_COUNT) /* to avoid spurious gcc warning */ \ | |
4a705c5c | 523 | (ssid) = 0; \ |
cb4a3167 AS |
524 | else \ |
525 | for_each_set_bit(ssid, ss_maskp, CGROUP_SUBSYS_COUNT) \ | |
526 | if (((ss) = cgroup_subsys[ssid]) && false) \ | |
527 | break; \ | |
528 | else | |
529 | ||
985ed670 TH |
530 | /* iterate across the hierarchies */ |
531 | #define for_each_root(root) \ | |
5549c497 | 532 | list_for_each_entry((root), &cgroup_roots, root_list) |
ddbcc7e8 | 533 | |
f8f22e53 TH |
534 | /* iterate over child cgrps, lock should be held throughout iteration */ |
535 | #define cgroup_for_each_live_child(child, cgrp) \ | |
d5c419b6 | 536 | list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
8353da1f | 537 | if (({ lockdep_assert_held(&cgroup_mutex); \ |
f8f22e53 TH |
538 | cgroup_is_dead(child); })) \ |
539 | ; \ | |
540 | else | |
7ae1bad9 | 541 | |
81a6a5cd | 542 | static void cgroup_release_agent(struct work_struct *work); |
bd89aabc | 543 | static void check_for_release(struct cgroup *cgrp); |
81a6a5cd | 544 | |
69d0206c TH |
545 | /* |
546 | * A cgroup can be associated with multiple css_sets as different tasks may | |
547 | * belong to different cgroups on different hierarchies. In the other | |
548 | * direction, a css_set is naturally associated with multiple cgroups. | |
549 | * This M:N relationship is represented by the following link structure | |
550 | * which exists for each association and allows traversing the associations | |
551 | * from both sides. | |
552 | */ | |
553 | struct cgrp_cset_link { | |
554 | /* the cgroup and css_set this link associates */ | |
555 | struct cgroup *cgrp; | |
556 | struct css_set *cset; | |
557 | ||
558 | /* list of cgrp_cset_links anchored at cgrp->cset_links */ | |
559 | struct list_head cset_link; | |
560 | ||
561 | /* list of cgrp_cset_links anchored at css_set->cgrp_links */ | |
562 | struct list_head cgrp_link; | |
817929ec PM |
563 | }; |
564 | ||
172a2c06 TH |
565 | /* |
566 | * The default css_set - used by init and its children prior to any | |
817929ec PM |
567 | * hierarchies being mounted. It contains a pointer to the root state |
568 | * for each subsystem. Also used to anchor the list of css_sets. Not | |
569 | * reference-counted, to improve performance when child cgroups | |
570 | * haven't been created. | |
571 | */ | |
5024ae29 | 572 | struct css_set init_css_set = { |
172a2c06 TH |
573 | .refcount = ATOMIC_INIT(1), |
574 | .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), | |
575 | .tasks = LIST_HEAD_INIT(init_css_set.tasks), | |
576 | .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), | |
577 | .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), | |
578 | .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), | |
579 | }; | |
817929ec | 580 | |
172a2c06 | 581 | static int css_set_count = 1; /* 1 for init_css_set */ |
817929ec | 582 | |
842b597e TH |
583 | /** |
584 | * cgroup_update_populated - updated populated count of a cgroup | |
585 | * @cgrp: the target cgroup | |
586 | * @populated: inc or dec populated count | |
587 | * | |
588 | * @cgrp is either getting the first task (css_set) or losing the last. | |
589 | * Update @cgrp->populated_cnt accordingly. The count is propagated | |
590 | * towards root so that a given cgroup's populated_cnt is zero iff the | |
591 | * cgroup and all its descendants are empty. | |
592 | * | |
593 | * @cgrp's interface file "cgroup.populated" is zero if | |
594 | * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt | |
595 | * changes from or to zero, userland is notified that the content of the | |
596 | * interface file has changed. This can be used to detect when @cgrp and | |
597 | * its descendants become populated or empty. | |
598 | */ | |
599 | static void cgroup_update_populated(struct cgroup *cgrp, bool populated) | |
600 | { | |
601 | lockdep_assert_held(&css_set_rwsem); | |
602 | ||
603 | do { | |
604 | bool trigger; | |
605 | ||
606 | if (populated) | |
607 | trigger = !cgrp->populated_cnt++; | |
608 | else | |
609 | trigger = !--cgrp->populated_cnt; | |
610 | ||
611 | if (!trigger) | |
612 | break; | |
613 | ||
4a07c222 TH |
614 | if (cgrp->events_kn) |
615 | kernfs_notify(cgrp->events_kn); | |
d51f39b0 | 616 | cgrp = cgroup_parent(cgrp); |
842b597e TH |
617 | } while (cgrp); |
618 | } | |
619 | ||
7717f7ba PM |
620 | /* |
621 | * hash table for cgroup groups. This improves the performance to find | |
622 | * an existing css_set. This hash doesn't (currently) take into | |
623 | * account cgroups in empty hierarchies. | |
624 | */ | |
472b1053 | 625 | #define CSS_SET_HASH_BITS 7 |
0ac801fe | 626 | static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
472b1053 | 627 | |
0ac801fe | 628 | static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
472b1053 | 629 | { |
0ac801fe | 630 | unsigned long key = 0UL; |
30159ec7 TH |
631 | struct cgroup_subsys *ss; |
632 | int i; | |
472b1053 | 633 | |
30159ec7 | 634 | for_each_subsys(ss, i) |
0ac801fe LZ |
635 | key += (unsigned long)css[i]; |
636 | key = (key >> 16) ^ key; | |
472b1053 | 637 | |
0ac801fe | 638 | return key; |
472b1053 LZ |
639 | } |
640 | ||
a25eb52e | 641 | static void put_css_set_locked(struct css_set *cset) |
b4f48b63 | 642 | { |
69d0206c | 643 | struct cgrp_cset_link *link, *tmp_link; |
2d8f243a TH |
644 | struct cgroup_subsys *ss; |
645 | int ssid; | |
5abb8855 | 646 | |
89c5509b TH |
647 | lockdep_assert_held(&css_set_rwsem); |
648 | ||
649 | if (!atomic_dec_and_test(&cset->refcount)) | |
146aa1bd | 650 | return; |
81a6a5cd | 651 | |
2c6ab6d2 | 652 | /* This css_set is dead. unlink it and release cgroup refcounts */ |
2d8f243a TH |
653 | for_each_subsys(ss, ssid) |
654 | list_del(&cset->e_cset_node[ssid]); | |
5abb8855 | 655 | hash_del(&cset->hlist); |
2c6ab6d2 PM |
656 | css_set_count--; |
657 | ||
69d0206c | 658 | list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
2c6ab6d2 | 659 | struct cgroup *cgrp = link->cgrp; |
5abb8855 | 660 | |
69d0206c TH |
661 | list_del(&link->cset_link); |
662 | list_del(&link->cgrp_link); | |
71b5707e | 663 | |
96d365e0 | 664 | /* @cgrp can't go away while we're holding css_set_rwsem */ |
842b597e TH |
665 | if (list_empty(&cgrp->cset_links)) { |
666 | cgroup_update_populated(cgrp, false); | |
a25eb52e | 667 | check_for_release(cgrp); |
81a6a5cd | 668 | } |
2c6ab6d2 PM |
669 | |
670 | kfree(link); | |
81a6a5cd | 671 | } |
2c6ab6d2 | 672 | |
5abb8855 | 673 | kfree_rcu(cset, rcu_head); |
b4f48b63 PM |
674 | } |
675 | ||
a25eb52e | 676 | static void put_css_set(struct css_set *cset) |
89c5509b TH |
677 | { |
678 | /* | |
679 | * Ensure that the refcount doesn't hit zero while any readers | |
680 | * can see it. Similar to atomic_dec_and_lock(), but for an | |
681 | * rwlock | |
682 | */ | |
683 | if (atomic_add_unless(&cset->refcount, -1, 1)) | |
684 | return; | |
685 | ||
686 | down_write(&css_set_rwsem); | |
a25eb52e | 687 | put_css_set_locked(cset); |
89c5509b TH |
688 | up_write(&css_set_rwsem); |
689 | } | |
690 | ||
817929ec PM |
691 | /* |
692 | * refcounted get/put for css_set objects | |
693 | */ | |
5abb8855 | 694 | static inline void get_css_set(struct css_set *cset) |
817929ec | 695 | { |
5abb8855 | 696 | atomic_inc(&cset->refcount); |
817929ec PM |
697 | } |
698 | ||
b326f9d0 | 699 | /** |
7717f7ba | 700 | * compare_css_sets - helper function for find_existing_css_set(). |
5abb8855 TH |
701 | * @cset: candidate css_set being tested |
702 | * @old_cset: existing css_set for a task | |
7717f7ba PM |
703 | * @new_cgrp: cgroup that's being entered by the task |
704 | * @template: desired set of css pointers in css_set (pre-calculated) | |
705 | * | |
6f4b7e63 | 706 | * Returns true if "cset" matches "old_cset" except for the hierarchy |
7717f7ba PM |
707 | * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
708 | */ | |
5abb8855 TH |
709 | static bool compare_css_sets(struct css_set *cset, |
710 | struct css_set *old_cset, | |
7717f7ba PM |
711 | struct cgroup *new_cgrp, |
712 | struct cgroup_subsys_state *template[]) | |
713 | { | |
714 | struct list_head *l1, *l2; | |
715 | ||
aec3dfcb TH |
716 | /* |
717 | * On the default hierarchy, there can be csets which are | |
718 | * associated with the same set of cgroups but different csses. | |
719 | * Let's first ensure that csses match. | |
720 | */ | |
721 | if (memcmp(template, cset->subsys, sizeof(cset->subsys))) | |
7717f7ba | 722 | return false; |
7717f7ba PM |
723 | |
724 | /* | |
725 | * Compare cgroup pointers in order to distinguish between | |
aec3dfcb TH |
726 | * different cgroups in hierarchies. As different cgroups may |
727 | * share the same effective css, this comparison is always | |
728 | * necessary. | |
7717f7ba | 729 | */ |
69d0206c TH |
730 | l1 = &cset->cgrp_links; |
731 | l2 = &old_cset->cgrp_links; | |
7717f7ba | 732 | while (1) { |
69d0206c | 733 | struct cgrp_cset_link *link1, *link2; |
5abb8855 | 734 | struct cgroup *cgrp1, *cgrp2; |
7717f7ba PM |
735 | |
736 | l1 = l1->next; | |
737 | l2 = l2->next; | |
738 | /* See if we reached the end - both lists are equal length. */ | |
69d0206c TH |
739 | if (l1 == &cset->cgrp_links) { |
740 | BUG_ON(l2 != &old_cset->cgrp_links); | |
7717f7ba PM |
741 | break; |
742 | } else { | |
69d0206c | 743 | BUG_ON(l2 == &old_cset->cgrp_links); |
7717f7ba PM |
744 | } |
745 | /* Locate the cgroups associated with these links. */ | |
69d0206c TH |
746 | link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
747 | link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); | |
748 | cgrp1 = link1->cgrp; | |
749 | cgrp2 = link2->cgrp; | |
7717f7ba | 750 | /* Hierarchies should be linked in the same order. */ |
5abb8855 | 751 | BUG_ON(cgrp1->root != cgrp2->root); |
7717f7ba PM |
752 | |
753 | /* | |
754 | * If this hierarchy is the hierarchy of the cgroup | |
755 | * that's changing, then we need to check that this | |
756 | * css_set points to the new cgroup; if it's any other | |
757 | * hierarchy, then this css_set should point to the | |
758 | * same cgroup as the old css_set. | |
759 | */ | |
5abb8855 TH |
760 | if (cgrp1->root == new_cgrp->root) { |
761 | if (cgrp1 != new_cgrp) | |
7717f7ba PM |
762 | return false; |
763 | } else { | |
5abb8855 | 764 | if (cgrp1 != cgrp2) |
7717f7ba PM |
765 | return false; |
766 | } | |
767 | } | |
768 | return true; | |
769 | } | |
770 | ||
b326f9d0 TH |
771 | /** |
772 | * find_existing_css_set - init css array and find the matching css_set | |
773 | * @old_cset: the css_set that we're using before the cgroup transition | |
774 | * @cgrp: the cgroup that we're moving into | |
775 | * @template: out param for the new set of csses, should be clear on entry | |
817929ec | 776 | */ |
5abb8855 TH |
777 | static struct css_set *find_existing_css_set(struct css_set *old_cset, |
778 | struct cgroup *cgrp, | |
779 | struct cgroup_subsys_state *template[]) | |
b4f48b63 | 780 | { |
3dd06ffa | 781 | struct cgroup_root *root = cgrp->root; |
30159ec7 | 782 | struct cgroup_subsys *ss; |
5abb8855 | 783 | struct css_set *cset; |
0ac801fe | 784 | unsigned long key; |
b326f9d0 | 785 | int i; |
817929ec | 786 | |
aae8aab4 BB |
787 | /* |
788 | * Build the set of subsystem state objects that we want to see in the | |
789 | * new css_set. while subsystems can change globally, the entries here | |
790 | * won't change, so no need for locking. | |
791 | */ | |
30159ec7 | 792 | for_each_subsys(ss, i) { |
f392e51c | 793 | if (root->subsys_mask & (1UL << i)) { |
aec3dfcb TH |
794 | /* |
795 | * @ss is in this hierarchy, so we want the | |
796 | * effective css from @cgrp. | |
797 | */ | |
798 | template[i] = cgroup_e_css(cgrp, ss); | |
817929ec | 799 | } else { |
aec3dfcb TH |
800 | /* |
801 | * @ss is not in this hierarchy, so we don't want | |
802 | * to change the css. | |
803 | */ | |
5abb8855 | 804 | template[i] = old_cset->subsys[i]; |
817929ec PM |
805 | } |
806 | } | |
807 | ||
0ac801fe | 808 | key = css_set_hash(template); |
5abb8855 TH |
809 | hash_for_each_possible(css_set_table, cset, hlist, key) { |
810 | if (!compare_css_sets(cset, old_cset, cgrp, template)) | |
7717f7ba PM |
811 | continue; |
812 | ||
813 | /* This css_set matches what we need */ | |
5abb8855 | 814 | return cset; |
472b1053 | 815 | } |
817929ec PM |
816 | |
817 | /* No existing cgroup group matched */ | |
818 | return NULL; | |
819 | } | |
820 | ||
69d0206c | 821 | static void free_cgrp_cset_links(struct list_head *links_to_free) |
36553434 | 822 | { |
69d0206c | 823 | struct cgrp_cset_link *link, *tmp_link; |
36553434 | 824 | |
69d0206c TH |
825 | list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
826 | list_del(&link->cset_link); | |
36553434 LZ |
827 | kfree(link); |
828 | } | |
829 | } | |
830 | ||
69d0206c TH |
831 | /** |
832 | * allocate_cgrp_cset_links - allocate cgrp_cset_links | |
833 | * @count: the number of links to allocate | |
834 | * @tmp_links: list_head the allocated links are put on | |
835 | * | |
836 | * Allocate @count cgrp_cset_link structures and chain them on @tmp_links | |
837 | * through ->cset_link. Returns 0 on success or -errno. | |
817929ec | 838 | */ |
69d0206c | 839 | static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
817929ec | 840 | { |
69d0206c | 841 | struct cgrp_cset_link *link; |
817929ec | 842 | int i; |
69d0206c TH |
843 | |
844 | INIT_LIST_HEAD(tmp_links); | |
845 | ||
817929ec | 846 | for (i = 0; i < count; i++) { |
f4f4be2b | 847 | link = kzalloc(sizeof(*link), GFP_KERNEL); |
817929ec | 848 | if (!link) { |
69d0206c | 849 | free_cgrp_cset_links(tmp_links); |
817929ec PM |
850 | return -ENOMEM; |
851 | } | |
69d0206c | 852 | list_add(&link->cset_link, tmp_links); |
817929ec PM |
853 | } |
854 | return 0; | |
855 | } | |
856 | ||
c12f65d4 LZ |
857 | /** |
858 | * link_css_set - a helper function to link a css_set to a cgroup | |
69d0206c | 859 | * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
5abb8855 | 860 | * @cset: the css_set to be linked |
c12f65d4 LZ |
861 | * @cgrp: the destination cgroup |
862 | */ | |
69d0206c TH |
863 | static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
864 | struct cgroup *cgrp) | |
c12f65d4 | 865 | { |
69d0206c | 866 | struct cgrp_cset_link *link; |
c12f65d4 | 867 | |
69d0206c | 868 | BUG_ON(list_empty(tmp_links)); |
6803c006 TH |
869 | |
870 | if (cgroup_on_dfl(cgrp)) | |
871 | cset->dfl_cgrp = cgrp; | |
872 | ||
69d0206c TH |
873 | link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
874 | link->cset = cset; | |
7717f7ba | 875 | link->cgrp = cgrp; |
842b597e TH |
876 | |
877 | if (list_empty(&cgrp->cset_links)) | |
878 | cgroup_update_populated(cgrp, true); | |
69d0206c | 879 | list_move(&link->cset_link, &cgrp->cset_links); |
842b597e | 880 | |
7717f7ba PM |
881 | /* |
882 | * Always add links to the tail of the list so that the list | |
883 | * is sorted by order of hierarchy creation | |
884 | */ | |
69d0206c | 885 | list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
c12f65d4 LZ |
886 | } |
887 | ||
b326f9d0 TH |
888 | /** |
889 | * find_css_set - return a new css_set with one cgroup updated | |
890 | * @old_cset: the baseline css_set | |
891 | * @cgrp: the cgroup to be updated | |
892 | * | |
893 | * Return a new css_set that's equivalent to @old_cset, but with @cgrp | |
894 | * substituted into the appropriate hierarchy. | |
817929ec | 895 | */ |
5abb8855 TH |
896 | static struct css_set *find_css_set(struct css_set *old_cset, |
897 | struct cgroup *cgrp) | |
817929ec | 898 | { |
b326f9d0 | 899 | struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
5abb8855 | 900 | struct css_set *cset; |
69d0206c TH |
901 | struct list_head tmp_links; |
902 | struct cgrp_cset_link *link; | |
2d8f243a | 903 | struct cgroup_subsys *ss; |
0ac801fe | 904 | unsigned long key; |
2d8f243a | 905 | int ssid; |
472b1053 | 906 | |
b326f9d0 TH |
907 | lockdep_assert_held(&cgroup_mutex); |
908 | ||
817929ec PM |
909 | /* First see if we already have a cgroup group that matches |
910 | * the desired set */ | |
96d365e0 | 911 | down_read(&css_set_rwsem); |
5abb8855 TH |
912 | cset = find_existing_css_set(old_cset, cgrp, template); |
913 | if (cset) | |
914 | get_css_set(cset); | |
96d365e0 | 915 | up_read(&css_set_rwsem); |
817929ec | 916 | |
5abb8855 TH |
917 | if (cset) |
918 | return cset; | |
817929ec | 919 | |
f4f4be2b | 920 | cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
5abb8855 | 921 | if (!cset) |
817929ec PM |
922 | return NULL; |
923 | ||
69d0206c | 924 | /* Allocate all the cgrp_cset_link objects that we'll need */ |
9871bf95 | 925 | if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
5abb8855 | 926 | kfree(cset); |
817929ec PM |
927 | return NULL; |
928 | } | |
929 | ||
5abb8855 | 930 | atomic_set(&cset->refcount, 1); |
69d0206c | 931 | INIT_LIST_HEAD(&cset->cgrp_links); |
5abb8855 | 932 | INIT_LIST_HEAD(&cset->tasks); |
c7561128 | 933 | INIT_LIST_HEAD(&cset->mg_tasks); |
1958d2d5 | 934 | INIT_LIST_HEAD(&cset->mg_preload_node); |
b3dc094e | 935 | INIT_LIST_HEAD(&cset->mg_node); |
5abb8855 | 936 | INIT_HLIST_NODE(&cset->hlist); |
817929ec PM |
937 | |
938 | /* Copy the set of subsystem state objects generated in | |
939 | * find_existing_css_set() */ | |
5abb8855 | 940 | memcpy(cset->subsys, template, sizeof(cset->subsys)); |
817929ec | 941 | |
96d365e0 | 942 | down_write(&css_set_rwsem); |
817929ec | 943 | /* Add reference counts and links from the new css_set. */ |
69d0206c | 944 | list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
7717f7ba | 945 | struct cgroup *c = link->cgrp; |
69d0206c | 946 | |
7717f7ba PM |
947 | if (c->root == cgrp->root) |
948 | c = cgrp; | |
69d0206c | 949 | link_css_set(&tmp_links, cset, c); |
7717f7ba | 950 | } |
817929ec | 951 | |
69d0206c | 952 | BUG_ON(!list_empty(&tmp_links)); |
817929ec | 953 | |
817929ec | 954 | css_set_count++; |
472b1053 | 955 | |
2d8f243a | 956 | /* Add @cset to the hash table */ |
5abb8855 TH |
957 | key = css_set_hash(cset->subsys); |
958 | hash_add(css_set_table, &cset->hlist, key); | |
472b1053 | 959 | |
2d8f243a TH |
960 | for_each_subsys(ss, ssid) |
961 | list_add_tail(&cset->e_cset_node[ssid], | |
962 | &cset->subsys[ssid]->cgroup->e_csets[ssid]); | |
963 | ||
96d365e0 | 964 | up_write(&css_set_rwsem); |
817929ec | 965 | |
5abb8855 | 966 | return cset; |
b4f48b63 PM |
967 | } |
968 | ||
3dd06ffa | 969 | static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
7717f7ba | 970 | { |
3dd06ffa | 971 | struct cgroup *root_cgrp = kf_root->kn->priv; |
2bd59d48 | 972 | |
3dd06ffa | 973 | return root_cgrp->root; |
2bd59d48 TH |
974 | } |
975 | ||
3dd06ffa | 976 | static int cgroup_init_root_id(struct cgroup_root *root) |
f2e85d57 TH |
977 | { |
978 | int id; | |
979 | ||
980 | lockdep_assert_held(&cgroup_mutex); | |
981 | ||
985ed670 | 982 | id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
f2e85d57 TH |
983 | if (id < 0) |
984 | return id; | |
985 | ||
986 | root->hierarchy_id = id; | |
987 | return 0; | |
988 | } | |
989 | ||
3dd06ffa | 990 | static void cgroup_exit_root_id(struct cgroup_root *root) |
f2e85d57 TH |
991 | { |
992 | lockdep_assert_held(&cgroup_mutex); | |
993 | ||
994 | if (root->hierarchy_id) { | |
995 | idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); | |
996 | root->hierarchy_id = 0; | |
997 | } | |
998 | } | |
999 | ||
3dd06ffa | 1000 | static void cgroup_free_root(struct cgroup_root *root) |
f2e85d57 TH |
1001 | { |
1002 | if (root) { | |
d0f702e6 | 1003 | /* hierarchy ID should already have been released */ |
f2e85d57 TH |
1004 | WARN_ON_ONCE(root->hierarchy_id); |
1005 | ||
1006 | idr_destroy(&root->cgroup_idr); | |
1007 | kfree(root); | |
1008 | } | |
1009 | } | |
1010 | ||
3dd06ffa | 1011 | static void cgroup_destroy_root(struct cgroup_root *root) |
59f5296b | 1012 | { |
3dd06ffa | 1013 | struct cgroup *cgrp = &root->cgrp; |
f2e85d57 | 1014 | struct cgrp_cset_link *link, *tmp_link; |
f2e85d57 | 1015 | |
2bd59d48 | 1016 | mutex_lock(&cgroup_mutex); |
f2e85d57 | 1017 | |
776f02fa | 1018 | BUG_ON(atomic_read(&root->nr_cgrps)); |
d5c419b6 | 1019 | BUG_ON(!list_empty(&cgrp->self.children)); |
f2e85d57 | 1020 | |
f2e85d57 | 1021 | /* Rebind all subsystems back to the default hierarchy */ |
f392e51c | 1022 | rebind_subsystems(&cgrp_dfl_root, root->subsys_mask); |
7717f7ba | 1023 | |
7717f7ba | 1024 | /* |
f2e85d57 TH |
1025 | * Release all the links from cset_links to this hierarchy's |
1026 | * root cgroup | |
7717f7ba | 1027 | */ |
96d365e0 | 1028 | down_write(&css_set_rwsem); |
f2e85d57 TH |
1029 | |
1030 | list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { | |
1031 | list_del(&link->cset_link); | |
1032 | list_del(&link->cgrp_link); | |
1033 | kfree(link); | |
1034 | } | |
96d365e0 | 1035 | up_write(&css_set_rwsem); |
f2e85d57 TH |
1036 | |
1037 | if (!list_empty(&root->root_list)) { | |
1038 | list_del(&root->root_list); | |
1039 | cgroup_root_count--; | |
1040 | } | |
1041 | ||
1042 | cgroup_exit_root_id(root); | |
1043 | ||
1044 | mutex_unlock(&cgroup_mutex); | |
f2e85d57 | 1045 | |
2bd59d48 | 1046 | kernfs_destroy_root(root->kf_root); |
f2e85d57 TH |
1047 | cgroup_free_root(root); |
1048 | } | |
1049 | ||
ceb6a081 TH |
1050 | /* look up cgroup associated with given css_set on the specified hierarchy */ |
1051 | static struct cgroup *cset_cgroup_from_root(struct css_set *cset, | |
3dd06ffa | 1052 | struct cgroup_root *root) |
7717f7ba | 1053 | { |
7717f7ba PM |
1054 | struct cgroup *res = NULL; |
1055 | ||
96d365e0 TH |
1056 | lockdep_assert_held(&cgroup_mutex); |
1057 | lockdep_assert_held(&css_set_rwsem); | |
1058 | ||
5abb8855 | 1059 | if (cset == &init_css_set) { |
3dd06ffa | 1060 | res = &root->cgrp; |
7717f7ba | 1061 | } else { |
69d0206c TH |
1062 | struct cgrp_cset_link *link; |
1063 | ||
1064 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { | |
7717f7ba | 1065 | struct cgroup *c = link->cgrp; |
69d0206c | 1066 | |
7717f7ba PM |
1067 | if (c->root == root) { |
1068 | res = c; | |
1069 | break; | |
1070 | } | |
1071 | } | |
1072 | } | |
96d365e0 | 1073 | |
7717f7ba PM |
1074 | BUG_ON(!res); |
1075 | return res; | |
1076 | } | |
1077 | ||
ddbcc7e8 | 1078 | /* |
ceb6a081 TH |
1079 | * Return the cgroup for "task" from the given hierarchy. Must be |
1080 | * called with cgroup_mutex and css_set_rwsem held. | |
1081 | */ | |
1082 | static struct cgroup *task_cgroup_from_root(struct task_struct *task, | |
3dd06ffa | 1083 | struct cgroup_root *root) |
ceb6a081 TH |
1084 | { |
1085 | /* | |
1086 | * No need to lock the task - since we hold cgroup_mutex the | |
1087 | * task can't change groups, so the only thing that can happen | |
1088 | * is that it exits and its css is set back to init_css_set. | |
1089 | */ | |
1090 | return cset_cgroup_from_root(task_css_set(task), root); | |
1091 | } | |
1092 | ||
ddbcc7e8 | 1093 | /* |
ddbcc7e8 PM |
1094 | * A task must hold cgroup_mutex to modify cgroups. |
1095 | * | |
1096 | * Any task can increment and decrement the count field without lock. | |
1097 | * So in general, code holding cgroup_mutex can't rely on the count | |
1098 | * field not changing. However, if the count goes to zero, then only | |
956db3ca | 1099 | * cgroup_attach_task() can increment it again. Because a count of zero |
ddbcc7e8 PM |
1100 | * means that no tasks are currently attached, therefore there is no |
1101 | * way a task attached to that cgroup can fork (the other way to | |
1102 | * increment the count). So code holding cgroup_mutex can safely | |
1103 | * assume that if the count is zero, it will stay zero. Similarly, if | |
1104 | * a task holds cgroup_mutex on a cgroup with zero count, it | |
1105 | * knows that the cgroup won't be removed, as cgroup_rmdir() | |
1106 | * needs that mutex. | |
1107 | * | |
ddbcc7e8 PM |
1108 | * A cgroup can only be deleted if both its 'count' of using tasks |
1109 | * is zero, and its list of 'children' cgroups is empty. Since all | |
1110 | * tasks in the system use _some_ cgroup, and since there is always at | |
3dd06ffa | 1111 | * least one task in the system (init, pid == 1), therefore, root cgroup |
ddbcc7e8 | 1112 | * always has either children cgroups and/or using tasks. So we don't |
3dd06ffa | 1113 | * need a special hack to ensure that root cgroup cannot be deleted. |
ddbcc7e8 PM |
1114 | * |
1115 | * P.S. One more locking exception. RCU is used to guard the | |
956db3ca | 1116 | * update of a tasks cgroup pointer by cgroup_attach_task() |
ddbcc7e8 PM |
1117 | */ |
1118 | ||
2bd59d48 | 1119 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
828c0950 | 1120 | static const struct file_operations proc_cgroupstats_operations; |
a424316c | 1121 | |
8d7e6fb0 TH |
1122 | static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
1123 | char *buf) | |
ddbcc7e8 | 1124 | { |
3e1d2eed TH |
1125 | struct cgroup_subsys *ss = cft->ss; |
1126 | ||
8d7e6fb0 TH |
1127 | if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
1128 | !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) | |
1129 | snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", | |
3e1d2eed TH |
1130 | cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
1131 | cft->name); | |
8d7e6fb0 TH |
1132 | else |
1133 | strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX); | |
1134 | return buf; | |
ddbcc7e8 PM |
1135 | } |
1136 | ||
f2e85d57 TH |
1137 | /** |
1138 | * cgroup_file_mode - deduce file mode of a control file | |
1139 | * @cft: the control file in question | |
1140 | * | |
7dbdb199 | 1141 | * S_IRUGO for read, S_IWUSR for write. |
f2e85d57 TH |
1142 | */ |
1143 | static umode_t cgroup_file_mode(const struct cftype *cft) | |
65dff759 | 1144 | { |
f2e85d57 | 1145 | umode_t mode = 0; |
65dff759 | 1146 | |
f2e85d57 TH |
1147 | if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
1148 | mode |= S_IRUGO; | |
1149 | ||
7dbdb199 TH |
1150 | if (cft->write_u64 || cft->write_s64 || cft->write) { |
1151 | if (cft->flags & CFTYPE_WORLD_WRITABLE) | |
1152 | mode |= S_IWUGO; | |
1153 | else | |
1154 | mode |= S_IWUSR; | |
1155 | } | |
f2e85d57 TH |
1156 | |
1157 | return mode; | |
65dff759 LZ |
1158 | } |
1159 | ||
59f5296b | 1160 | static void cgroup_get(struct cgroup *cgrp) |
be445626 | 1161 | { |
2bd59d48 | 1162 | WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
9d755d33 | 1163 | css_get(&cgrp->self); |
be445626 LZ |
1164 | } |
1165 | ||
aa32362f LZ |
1166 | static bool cgroup_tryget(struct cgroup *cgrp) |
1167 | { | |
1168 | return css_tryget(&cgrp->self); | |
1169 | } | |
1170 | ||
59f5296b | 1171 | static void cgroup_put(struct cgroup *cgrp) |
be445626 | 1172 | { |
9d755d33 | 1173 | css_put(&cgrp->self); |
be445626 LZ |
1174 | } |
1175 | ||
af0ba678 | 1176 | /** |
0f060deb | 1177 | * cgroup_calc_child_subsys_mask - calculate child_subsys_mask |
af0ba678 | 1178 | * @cgrp: the target cgroup |
0f060deb | 1179 | * @subtree_control: the new subtree_control mask to consider |
af0ba678 TH |
1180 | * |
1181 | * On the default hierarchy, a subsystem may request other subsystems to be | |
1182 | * enabled together through its ->depends_on mask. In such cases, more | |
1183 | * subsystems than specified in "cgroup.subtree_control" may be enabled. | |
1184 | * | |
0f060deb TH |
1185 | * This function calculates which subsystems need to be enabled if |
1186 | * @subtree_control is to be applied to @cgrp. The returned mask is always | |
1187 | * a superset of @subtree_control and follows the usual hierarchy rules. | |
af0ba678 | 1188 | */ |
8ab456ac AS |
1189 | static unsigned long cgroup_calc_child_subsys_mask(struct cgroup *cgrp, |
1190 | unsigned long subtree_control) | |
667c2491 | 1191 | { |
af0ba678 | 1192 | struct cgroup *parent = cgroup_parent(cgrp); |
8ab456ac | 1193 | unsigned long cur_ss_mask = subtree_control; |
af0ba678 TH |
1194 | struct cgroup_subsys *ss; |
1195 | int ssid; | |
1196 | ||
1197 | lockdep_assert_held(&cgroup_mutex); | |
1198 | ||
0f060deb TH |
1199 | if (!cgroup_on_dfl(cgrp)) |
1200 | return cur_ss_mask; | |
af0ba678 TH |
1201 | |
1202 | while (true) { | |
8ab456ac | 1203 | unsigned long new_ss_mask = cur_ss_mask; |
af0ba678 | 1204 | |
a966a4ed AS |
1205 | for_each_subsys_which(ss, ssid, &cur_ss_mask) |
1206 | new_ss_mask |= ss->depends_on; | |
af0ba678 TH |
1207 | |
1208 | /* | |
1209 | * Mask out subsystems which aren't available. This can | |
1210 | * happen only if some depended-upon subsystems were bound | |
1211 | * to non-default hierarchies. | |
1212 | */ | |
1213 | if (parent) | |
1214 | new_ss_mask &= parent->child_subsys_mask; | |
1215 | else | |
1216 | new_ss_mask &= cgrp->root->subsys_mask; | |
1217 | ||
1218 | if (new_ss_mask == cur_ss_mask) | |
1219 | break; | |
1220 | cur_ss_mask = new_ss_mask; | |
1221 | } | |
1222 | ||
0f060deb TH |
1223 | return cur_ss_mask; |
1224 | } | |
1225 | ||
1226 | /** | |
1227 | * cgroup_refresh_child_subsys_mask - update child_subsys_mask | |
1228 | * @cgrp: the target cgroup | |
1229 | * | |
1230 | * Update @cgrp->child_subsys_mask according to the current | |
1231 | * @cgrp->subtree_control using cgroup_calc_child_subsys_mask(). | |
1232 | */ | |
1233 | static void cgroup_refresh_child_subsys_mask(struct cgroup *cgrp) | |
1234 | { | |
1235 | cgrp->child_subsys_mask = | |
1236 | cgroup_calc_child_subsys_mask(cgrp, cgrp->subtree_control); | |
667c2491 TH |
1237 | } |
1238 | ||
a9746d8d TH |
1239 | /** |
1240 | * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods | |
1241 | * @kn: the kernfs_node being serviced | |
1242 | * | |
1243 | * This helper undoes cgroup_kn_lock_live() and should be invoked before | |
1244 | * the method finishes if locking succeeded. Note that once this function | |
1245 | * returns the cgroup returned by cgroup_kn_lock_live() may become | |
1246 | * inaccessible any time. If the caller intends to continue to access the | |
1247 | * cgroup, it should pin it before invoking this function. | |
1248 | */ | |
1249 | static void cgroup_kn_unlock(struct kernfs_node *kn) | |
ddbcc7e8 | 1250 | { |
a9746d8d TH |
1251 | struct cgroup *cgrp; |
1252 | ||
1253 | if (kernfs_type(kn) == KERNFS_DIR) | |
1254 | cgrp = kn->priv; | |
1255 | else | |
1256 | cgrp = kn->parent->priv; | |
1257 | ||
1258 | mutex_unlock(&cgroup_mutex); | |
a9746d8d TH |
1259 | |
1260 | kernfs_unbreak_active_protection(kn); | |
1261 | cgroup_put(cgrp); | |
ddbcc7e8 PM |
1262 | } |
1263 | ||
a9746d8d TH |
1264 | /** |
1265 | * cgroup_kn_lock_live - locking helper for cgroup kernfs methods | |
1266 | * @kn: the kernfs_node being serviced | |
1267 | * | |
1268 | * This helper is to be used by a cgroup kernfs method currently servicing | |
1269 | * @kn. It breaks the active protection, performs cgroup locking and | |
1270 | * verifies that the associated cgroup is alive. Returns the cgroup if | |
1271 | * alive; otherwise, %NULL. A successful return should be undone by a | |
1272 | * matching cgroup_kn_unlock() invocation. | |
1273 | * | |
1274 | * Any cgroup kernfs method implementation which requires locking the | |
1275 | * associated cgroup should use this helper. It avoids nesting cgroup | |
1276 | * locking under kernfs active protection and allows all kernfs operations | |
1277 | * including self-removal. | |
1278 | */ | |
1279 | static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn) | |
05ef1d7c | 1280 | { |
a9746d8d TH |
1281 | struct cgroup *cgrp; |
1282 | ||
1283 | if (kernfs_type(kn) == KERNFS_DIR) | |
1284 | cgrp = kn->priv; | |
1285 | else | |
1286 | cgrp = kn->parent->priv; | |
05ef1d7c | 1287 | |
2739d3cc | 1288 | /* |
01f6474c | 1289 | * We're gonna grab cgroup_mutex which nests outside kernfs |
a9746d8d TH |
1290 | * active_ref. cgroup liveliness check alone provides enough |
1291 | * protection against removal. Ensure @cgrp stays accessible and | |
1292 | * break the active_ref protection. | |
2739d3cc | 1293 | */ |
aa32362f LZ |
1294 | if (!cgroup_tryget(cgrp)) |
1295 | return NULL; | |
a9746d8d TH |
1296 | kernfs_break_active_protection(kn); |
1297 | ||
2bd59d48 | 1298 | mutex_lock(&cgroup_mutex); |
05ef1d7c | 1299 | |
a9746d8d TH |
1300 | if (!cgroup_is_dead(cgrp)) |
1301 | return cgrp; | |
1302 | ||
1303 | cgroup_kn_unlock(kn); | |
1304 | return NULL; | |
ddbcc7e8 | 1305 | } |
05ef1d7c | 1306 | |
2739d3cc | 1307 | static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
05ef1d7c | 1308 | { |
2bd59d48 | 1309 | char name[CGROUP_FILE_NAME_MAX]; |
05ef1d7c | 1310 | |
01f6474c | 1311 | lockdep_assert_held(&cgroup_mutex); |
2bd59d48 | 1312 | kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
05ef1d7c TH |
1313 | } |
1314 | ||
13af07df | 1315 | /** |
628f7cd4 | 1316 | * cgroup_clear_dir - remove subsys files in a cgroup directory |
8f89140a | 1317 | * @cgrp: target cgroup |
13af07df AR |
1318 | * @subsys_mask: mask of the subsystem ids whose files should be removed |
1319 | */ | |
8ab456ac | 1320 | static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) |
05ef1d7c | 1321 | { |
13af07df | 1322 | struct cgroup_subsys *ss; |
b420ba7d | 1323 | int i; |
05ef1d7c | 1324 | |
b420ba7d | 1325 | for_each_subsys(ss, i) { |
0adb0704 | 1326 | struct cftype *cfts; |
b420ba7d | 1327 | |
69dfa00c | 1328 | if (!(subsys_mask & (1 << i))) |
13af07df | 1329 | continue; |
0adb0704 TH |
1330 | list_for_each_entry(cfts, &ss->cfts, node) |
1331 | cgroup_addrm_files(cgrp, cfts, false); | |
13af07df | 1332 | } |
ddbcc7e8 PM |
1333 | } |
1334 | ||
ccdca218 TH |
1335 | /** |
1336 | * cgroup_populate_dir - create subsys files in a cgroup directory | |
1337 | * @cgrp: target cgroup | |
1338 | * @subsys_mask: mask of the subsystem ids whose files should be added | |
1339 | * | |
1340 | * On failure, no file is added. | |
1341 | */ | |
1342 | static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) | |
1343 | { | |
1344 | struct cgroup_subsys *ss; | |
1345 | int i, ret = 0; | |
1346 | ||
1347 | /* process cftsets of each subsystem */ | |
1348 | for_each_subsys(ss, i) { | |
1349 | struct cftype *cfts; | |
1350 | ||
1351 | if (!(subsys_mask & (1 << i))) | |
1352 | continue; | |
1353 | ||
1354 | list_for_each_entry(cfts, &ss->cfts, node) { | |
1355 | ret = cgroup_addrm_files(cgrp, cfts, true); | |
1356 | if (ret < 0) | |
1357 | goto err; | |
1358 | } | |
1359 | } | |
1360 | return 0; | |
1361 | err: | |
1362 | cgroup_clear_dir(cgrp, subsys_mask); | |
1363 | return ret; | |
1364 | } | |
1365 | ||
8ab456ac AS |
1366 | static int rebind_subsystems(struct cgroup_root *dst_root, |
1367 | unsigned long ss_mask) | |
ddbcc7e8 | 1368 | { |
30159ec7 | 1369 | struct cgroup_subsys *ss; |
8ab456ac | 1370 | unsigned long tmp_ss_mask; |
2d8f243a | 1371 | int ssid, i, ret; |
ddbcc7e8 | 1372 | |
ace2bee8 | 1373 | lockdep_assert_held(&cgroup_mutex); |
ddbcc7e8 | 1374 | |
a966a4ed | 1375 | for_each_subsys_which(ss, ssid, &ss_mask) { |
7fd8c565 TH |
1376 | /* if @ss has non-root csses attached to it, can't move */ |
1377 | if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss))) | |
3ed80a62 | 1378 | return -EBUSY; |
1d5be6b2 | 1379 | |
5df36032 | 1380 | /* can't move between two non-dummy roots either */ |
7fd8c565 | 1381 | if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
5df36032 | 1382 | return -EBUSY; |
ddbcc7e8 PM |
1383 | } |
1384 | ||
5533e011 TH |
1385 | /* skip creating root files on dfl_root for inhibited subsystems */ |
1386 | tmp_ss_mask = ss_mask; | |
1387 | if (dst_root == &cgrp_dfl_root) | |
1388 | tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask; | |
1389 | ||
1390 | ret = cgroup_populate_dir(&dst_root->cgrp, tmp_ss_mask); | |
a2dd4247 TH |
1391 | if (ret) { |
1392 | if (dst_root != &cgrp_dfl_root) | |
5df36032 | 1393 | return ret; |
ddbcc7e8 | 1394 | |
a2dd4247 TH |
1395 | /* |
1396 | * Rebinding back to the default root is not allowed to | |
1397 | * fail. Using both default and non-default roots should | |
1398 | * be rare. Moving subsystems back and forth even more so. | |
1399 | * Just warn about it and continue. | |
1400 | */ | |
1401 | if (cgrp_dfl_root_visible) { | |
8ab456ac | 1402 | pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n", |
a2a1f9ea | 1403 | ret, ss_mask); |
ed3d261b | 1404 | pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); |
a2dd4247 | 1405 | } |
5df36032 | 1406 | } |
3126121f TH |
1407 | |
1408 | /* | |
1409 | * Nothing can fail from this point on. Remove files for the | |
1410 | * removed subsystems and rebind each subsystem. | |
1411 | */ | |
a966a4ed AS |
1412 | for_each_subsys_which(ss, ssid, &ss_mask) |
1413 | cgroup_clear_dir(&ss->root->cgrp, 1 << ssid); | |
a8a648c4 | 1414 | |
a966a4ed | 1415 | for_each_subsys_which(ss, ssid, &ss_mask) { |
3dd06ffa | 1416 | struct cgroup_root *src_root; |
5df36032 | 1417 | struct cgroup_subsys_state *css; |
2d8f243a | 1418 | struct css_set *cset; |
a8a648c4 | 1419 | |
5df36032 | 1420 | src_root = ss->root; |
3dd06ffa | 1421 | css = cgroup_css(&src_root->cgrp, ss); |
a8a648c4 | 1422 | |
3dd06ffa | 1423 | WARN_ON(!css || cgroup_css(&dst_root->cgrp, ss)); |
73e80ed8 | 1424 | |
3dd06ffa TH |
1425 | RCU_INIT_POINTER(src_root->cgrp.subsys[ssid], NULL); |
1426 | rcu_assign_pointer(dst_root->cgrp.subsys[ssid], css); | |
5df36032 | 1427 | ss->root = dst_root; |
3dd06ffa | 1428 | css->cgroup = &dst_root->cgrp; |
73e80ed8 | 1429 | |
2d8f243a TH |
1430 | down_write(&css_set_rwsem); |
1431 | hash_for_each(css_set_table, i, cset, hlist) | |
1432 | list_move_tail(&cset->e_cset_node[ss->id], | |
1433 | &dst_root->cgrp.e_csets[ss->id]); | |
1434 | up_write(&css_set_rwsem); | |
1435 | ||
f392e51c | 1436 | src_root->subsys_mask &= ~(1 << ssid); |
667c2491 TH |
1437 | src_root->cgrp.subtree_control &= ~(1 << ssid); |
1438 | cgroup_refresh_child_subsys_mask(&src_root->cgrp); | |
f392e51c | 1439 | |
bd53d617 | 1440 | /* default hierarchy doesn't enable controllers by default */ |
f392e51c | 1441 | dst_root->subsys_mask |= 1 << ssid; |
49d1dc4b TH |
1442 | if (dst_root == &cgrp_dfl_root) { |
1443 | static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); | |
1444 | } else { | |
667c2491 TH |
1445 | dst_root->cgrp.subtree_control |= 1 << ssid; |
1446 | cgroup_refresh_child_subsys_mask(&dst_root->cgrp); | |
49d1dc4b | 1447 | static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
667c2491 | 1448 | } |
a8a648c4 | 1449 | |
5df36032 TH |
1450 | if (ss->bind) |
1451 | ss->bind(css); | |
ddbcc7e8 | 1452 | } |
ddbcc7e8 | 1453 | |
a2dd4247 | 1454 | kernfs_activate(dst_root->cgrp.kn); |
ddbcc7e8 PM |
1455 | return 0; |
1456 | } | |
1457 | ||
2bd59d48 TH |
1458 | static int cgroup_show_options(struct seq_file *seq, |
1459 | struct kernfs_root *kf_root) | |
ddbcc7e8 | 1460 | { |
3dd06ffa | 1461 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1462 | struct cgroup_subsys *ss; |
b85d2040 | 1463 | int ssid; |
ddbcc7e8 | 1464 | |
d98817d4 TH |
1465 | if (root != &cgrp_dfl_root) |
1466 | for_each_subsys(ss, ssid) | |
1467 | if (root->subsys_mask & (1 << ssid)) | |
61e57c0c | 1468 | seq_show_option(seq, ss->legacy_name, NULL); |
93438629 | 1469 | if (root->flags & CGRP_ROOT_NOPREFIX) |
ddbcc7e8 | 1470 | seq_puts(seq, ",noprefix"); |
93438629 | 1471 | if (root->flags & CGRP_ROOT_XATTR) |
03b1cde6 | 1472 | seq_puts(seq, ",xattr"); |
69e943b7 TH |
1473 | |
1474 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1475 | if (strlen(root->release_agent_path)) |
a068acf2 KC |
1476 | seq_show_option(seq, "release_agent", |
1477 | root->release_agent_path); | |
69e943b7 TH |
1478 | spin_unlock(&release_agent_path_lock); |
1479 | ||
3dd06ffa | 1480 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
97978e6d | 1481 | seq_puts(seq, ",clone_children"); |
c6d57f33 | 1482 | if (strlen(root->name)) |
a068acf2 | 1483 | seq_show_option(seq, "name", root->name); |
ddbcc7e8 PM |
1484 | return 0; |
1485 | } | |
1486 | ||
1487 | struct cgroup_sb_opts { | |
8ab456ac | 1488 | unsigned long subsys_mask; |
69dfa00c | 1489 | unsigned int flags; |
81a6a5cd | 1490 | char *release_agent; |
2260e7fc | 1491 | bool cpuset_clone_children; |
c6d57f33 | 1492 | char *name; |
2c6ab6d2 PM |
1493 | /* User explicitly requested empty subsystem */ |
1494 | bool none; | |
ddbcc7e8 PM |
1495 | }; |
1496 | ||
cf5d5941 | 1497 | static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1498 | { |
32a8cf23 DL |
1499 | char *token, *o = data; |
1500 | bool all_ss = false, one_ss = false; | |
8ab456ac | 1501 | unsigned long mask = -1UL; |
30159ec7 | 1502 | struct cgroup_subsys *ss; |
7b9a6ba5 | 1503 | int nr_opts = 0; |
30159ec7 | 1504 | int i; |
f9ab5b5b LZ |
1505 | |
1506 | #ifdef CONFIG_CPUSETS | |
69dfa00c | 1507 | mask = ~(1U << cpuset_cgrp_id); |
f9ab5b5b | 1508 | #endif |
ddbcc7e8 | 1509 | |
c6d57f33 | 1510 | memset(opts, 0, sizeof(*opts)); |
ddbcc7e8 PM |
1511 | |
1512 | while ((token = strsep(&o, ",")) != NULL) { | |
7b9a6ba5 TH |
1513 | nr_opts++; |
1514 | ||
ddbcc7e8 PM |
1515 | if (!*token) |
1516 | return -EINVAL; | |
32a8cf23 | 1517 | if (!strcmp(token, "none")) { |
2c6ab6d2 PM |
1518 | /* Explicitly have no subsystems */ |
1519 | opts->none = true; | |
32a8cf23 DL |
1520 | continue; |
1521 | } | |
1522 | if (!strcmp(token, "all")) { | |
1523 | /* Mutually exclusive option 'all' + subsystem name */ | |
1524 | if (one_ss) | |
1525 | return -EINVAL; | |
1526 | all_ss = true; | |
1527 | continue; | |
1528 | } | |
873fe09e TH |
1529 | if (!strcmp(token, "__DEVEL__sane_behavior")) { |
1530 | opts->flags |= CGRP_ROOT_SANE_BEHAVIOR; | |
1531 | continue; | |
1532 | } | |
32a8cf23 | 1533 | if (!strcmp(token, "noprefix")) { |
93438629 | 1534 | opts->flags |= CGRP_ROOT_NOPREFIX; |
32a8cf23 DL |
1535 | continue; |
1536 | } | |
1537 | if (!strcmp(token, "clone_children")) { | |
2260e7fc | 1538 | opts->cpuset_clone_children = true; |
32a8cf23 DL |
1539 | continue; |
1540 | } | |
03b1cde6 | 1541 | if (!strcmp(token, "xattr")) { |
93438629 | 1542 | opts->flags |= CGRP_ROOT_XATTR; |
03b1cde6 AR |
1543 | continue; |
1544 | } | |
32a8cf23 | 1545 | if (!strncmp(token, "release_agent=", 14)) { |
81a6a5cd PM |
1546 | /* Specifying two release agents is forbidden */ |
1547 | if (opts->release_agent) | |
1548 | return -EINVAL; | |
c6d57f33 | 1549 | opts->release_agent = |
e400c285 | 1550 | kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
81a6a5cd PM |
1551 | if (!opts->release_agent) |
1552 | return -ENOMEM; | |
32a8cf23 DL |
1553 | continue; |
1554 | } | |
1555 | if (!strncmp(token, "name=", 5)) { | |
c6d57f33 PM |
1556 | const char *name = token + 5; |
1557 | /* Can't specify an empty name */ | |
1558 | if (!strlen(name)) | |
1559 | return -EINVAL; | |
1560 | /* Must match [\w.-]+ */ | |
1561 | for (i = 0; i < strlen(name); i++) { | |
1562 | char c = name[i]; | |
1563 | if (isalnum(c)) | |
1564 | continue; | |
1565 | if ((c == '.') || (c == '-') || (c == '_')) | |
1566 | continue; | |
1567 | return -EINVAL; | |
1568 | } | |
1569 | /* Specifying two names is forbidden */ | |
1570 | if (opts->name) | |
1571 | return -EINVAL; | |
1572 | opts->name = kstrndup(name, | |
e400c285 | 1573 | MAX_CGROUP_ROOT_NAMELEN - 1, |
c6d57f33 PM |
1574 | GFP_KERNEL); |
1575 | if (!opts->name) | |
1576 | return -ENOMEM; | |
32a8cf23 DL |
1577 | |
1578 | continue; | |
1579 | } | |
1580 | ||
30159ec7 | 1581 | for_each_subsys(ss, i) { |
3e1d2eed | 1582 | if (strcmp(token, ss->legacy_name)) |
32a8cf23 | 1583 | continue; |
fc5ed1e9 | 1584 | if (!cgroup_ssid_enabled(i)) |
32a8cf23 DL |
1585 | continue; |
1586 | ||
1587 | /* Mutually exclusive option 'all' + subsystem name */ | |
1588 | if (all_ss) | |
1589 | return -EINVAL; | |
69dfa00c | 1590 | opts->subsys_mask |= (1 << i); |
32a8cf23 DL |
1591 | one_ss = true; |
1592 | ||
1593 | break; | |
1594 | } | |
1595 | if (i == CGROUP_SUBSYS_COUNT) | |
1596 | return -ENOENT; | |
1597 | } | |
1598 | ||
873fe09e | 1599 | if (opts->flags & CGRP_ROOT_SANE_BEHAVIOR) { |
ed3d261b | 1600 | pr_warn("sane_behavior: this is still under development and its behaviors will change, proceed at your own risk\n"); |
7b9a6ba5 TH |
1601 | if (nr_opts != 1) { |
1602 | pr_err("sane_behavior: no other mount options allowed\n"); | |
873fe09e TH |
1603 | return -EINVAL; |
1604 | } | |
7b9a6ba5 | 1605 | return 0; |
873fe09e TH |
1606 | } |
1607 | ||
7b9a6ba5 TH |
1608 | /* |
1609 | * If the 'all' option was specified select all the subsystems, | |
1610 | * otherwise if 'none', 'name=' and a subsystem name options were | |
1611 | * not specified, let's default to 'all' | |
1612 | */ | |
1613 | if (all_ss || (!one_ss && !opts->none && !opts->name)) | |
1614 | for_each_subsys(ss, i) | |
fc5ed1e9 | 1615 | if (cgroup_ssid_enabled(i)) |
7b9a6ba5 TH |
1616 | opts->subsys_mask |= (1 << i); |
1617 | ||
1618 | /* | |
1619 | * We either have to specify by name or by subsystems. (So all | |
1620 | * empty hierarchies must have a name). | |
1621 | */ | |
1622 | if (!opts->subsys_mask && !opts->name) | |
1623 | return -EINVAL; | |
1624 | ||
f9ab5b5b LZ |
1625 | /* |
1626 | * Option noprefix was introduced just for backward compatibility | |
1627 | * with the old cpuset, so we allow noprefix only if mounting just | |
1628 | * the cpuset subsystem. | |
1629 | */ | |
93438629 | 1630 | if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
f9ab5b5b LZ |
1631 | return -EINVAL; |
1632 | ||
2c6ab6d2 | 1633 | /* Can't specify "none" and some subsystems */ |
a1a71b45 | 1634 | if (opts->subsys_mask && opts->none) |
2c6ab6d2 PM |
1635 | return -EINVAL; |
1636 | ||
ddbcc7e8 PM |
1637 | return 0; |
1638 | } | |
1639 | ||
2bd59d48 | 1640 | static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
ddbcc7e8 PM |
1641 | { |
1642 | int ret = 0; | |
3dd06ffa | 1643 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
ddbcc7e8 | 1644 | struct cgroup_sb_opts opts; |
8ab456ac | 1645 | unsigned long added_mask, removed_mask; |
ddbcc7e8 | 1646 | |
aa6ec29b TH |
1647 | if (root == &cgrp_dfl_root) { |
1648 | pr_err("remount is not allowed\n"); | |
873fe09e TH |
1649 | return -EINVAL; |
1650 | } | |
1651 | ||
ddbcc7e8 PM |
1652 | mutex_lock(&cgroup_mutex); |
1653 | ||
1654 | /* See what subsystems are wanted */ | |
1655 | ret = parse_cgroupfs_options(data, &opts); | |
1656 | if (ret) | |
1657 | goto out_unlock; | |
1658 | ||
f392e51c | 1659 | if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
ed3d261b | 1660 | pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
a2a1f9ea | 1661 | task_tgid_nr(current), current->comm); |
8b5a5a9d | 1662 | |
f392e51c TH |
1663 | added_mask = opts.subsys_mask & ~root->subsys_mask; |
1664 | removed_mask = root->subsys_mask & ~opts.subsys_mask; | |
13af07df | 1665 | |
cf5d5941 | 1666 | /* Don't allow flags or name to change at remount */ |
7450e90b | 1667 | if ((opts.flags ^ root->flags) || |
cf5d5941 | 1668 | (opts.name && strcmp(opts.name, root->name))) { |
69dfa00c | 1669 | pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
7450e90b | 1670 | opts.flags, opts.name ?: "", root->flags, root->name); |
c6d57f33 PM |
1671 | ret = -EINVAL; |
1672 | goto out_unlock; | |
1673 | } | |
1674 | ||
f172e67c | 1675 | /* remounting is not allowed for populated hierarchies */ |
d5c419b6 | 1676 | if (!list_empty(&root->cgrp.self.children)) { |
f172e67c | 1677 | ret = -EBUSY; |
0670e08b | 1678 | goto out_unlock; |
cf5d5941 | 1679 | } |
ddbcc7e8 | 1680 | |
5df36032 | 1681 | ret = rebind_subsystems(root, added_mask); |
3126121f | 1682 | if (ret) |
0670e08b | 1683 | goto out_unlock; |
ddbcc7e8 | 1684 | |
3dd06ffa | 1685 | rebind_subsystems(&cgrp_dfl_root, removed_mask); |
5df36032 | 1686 | |
69e943b7 TH |
1687 | if (opts.release_agent) { |
1688 | spin_lock(&release_agent_path_lock); | |
81a6a5cd | 1689 | strcpy(root->release_agent_path, opts.release_agent); |
69e943b7 TH |
1690 | spin_unlock(&release_agent_path_lock); |
1691 | } | |
ddbcc7e8 | 1692 | out_unlock: |
66bdc9cf | 1693 | kfree(opts.release_agent); |
c6d57f33 | 1694 | kfree(opts.name); |
ddbcc7e8 | 1695 | mutex_unlock(&cgroup_mutex); |
ddbcc7e8 PM |
1696 | return ret; |
1697 | } | |
1698 | ||
afeb0f9f TH |
1699 | /* |
1700 | * To reduce the fork() overhead for systems that are not actually using | |
1701 | * their cgroups capability, we don't maintain the lists running through | |
1702 | * each css_set to its tasks until we see the list actually used - in other | |
1703 | * words after the first mount. | |
1704 | */ | |
1705 | static bool use_task_css_set_links __read_mostly; | |
1706 | ||
1707 | static void cgroup_enable_task_cg_lists(void) | |
1708 | { | |
1709 | struct task_struct *p, *g; | |
1710 | ||
96d365e0 | 1711 | down_write(&css_set_rwsem); |
afeb0f9f TH |
1712 | |
1713 | if (use_task_css_set_links) | |
1714 | goto out_unlock; | |
1715 | ||
1716 | use_task_css_set_links = true; | |
1717 | ||
1718 | /* | |
1719 | * We need tasklist_lock because RCU is not safe against | |
1720 | * while_each_thread(). Besides, a forking task that has passed | |
1721 | * cgroup_post_fork() without seeing use_task_css_set_links = 1 | |
1722 | * is not guaranteed to have its child immediately visible in the | |
1723 | * tasklist if we walk through it with RCU. | |
1724 | */ | |
1725 | read_lock(&tasklist_lock); | |
1726 | do_each_thread(g, p) { | |
afeb0f9f TH |
1727 | WARN_ON_ONCE(!list_empty(&p->cg_list) || |
1728 | task_css_set(p) != &init_css_set); | |
1729 | ||
1730 | /* | |
1731 | * We should check if the process is exiting, otherwise | |
1732 | * it will race with cgroup_exit() in that the list | |
1733 | * entry won't be deleted though the process has exited. | |
f153ad11 TH |
1734 | * Do it while holding siglock so that we don't end up |
1735 | * racing against cgroup_exit(). | |
afeb0f9f | 1736 | */ |
f153ad11 | 1737 | spin_lock_irq(&p->sighand->siglock); |
eaf797ab TH |
1738 | if (!(p->flags & PF_EXITING)) { |
1739 | struct css_set *cset = task_css_set(p); | |
1740 | ||
1741 | list_add(&p->cg_list, &cset->tasks); | |
1742 | get_css_set(cset); | |
1743 | } | |
f153ad11 | 1744 | spin_unlock_irq(&p->sighand->siglock); |
afeb0f9f TH |
1745 | } while_each_thread(g, p); |
1746 | read_unlock(&tasklist_lock); | |
1747 | out_unlock: | |
96d365e0 | 1748 | up_write(&css_set_rwsem); |
afeb0f9f | 1749 | } |
ddbcc7e8 | 1750 | |
cc31edce PM |
1751 | static void init_cgroup_housekeeping(struct cgroup *cgrp) |
1752 | { | |
2d8f243a TH |
1753 | struct cgroup_subsys *ss; |
1754 | int ssid; | |
1755 | ||
d5c419b6 TH |
1756 | INIT_LIST_HEAD(&cgrp->self.sibling); |
1757 | INIT_LIST_HEAD(&cgrp->self.children); | |
69d0206c | 1758 | INIT_LIST_HEAD(&cgrp->cset_links); |
72a8cb30 BB |
1759 | INIT_LIST_HEAD(&cgrp->pidlists); |
1760 | mutex_init(&cgrp->pidlist_mutex); | |
9d800df1 | 1761 | cgrp->self.cgroup = cgrp; |
184faf32 | 1762 | cgrp->self.flags |= CSS_ONLINE; |
2d8f243a TH |
1763 | |
1764 | for_each_subsys(ss, ssid) | |
1765 | INIT_LIST_HEAD(&cgrp->e_csets[ssid]); | |
f8f22e53 TH |
1766 | |
1767 | init_waitqueue_head(&cgrp->offline_waitq); | |
971ff493 | 1768 | INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
cc31edce | 1769 | } |
c6d57f33 | 1770 | |
3dd06ffa | 1771 | static void init_cgroup_root(struct cgroup_root *root, |
172a2c06 | 1772 | struct cgroup_sb_opts *opts) |
ddbcc7e8 | 1773 | { |
3dd06ffa | 1774 | struct cgroup *cgrp = &root->cgrp; |
b0ca5a84 | 1775 | |
ddbcc7e8 | 1776 | INIT_LIST_HEAD(&root->root_list); |
3c9c825b | 1777 | atomic_set(&root->nr_cgrps, 1); |
bd89aabc | 1778 | cgrp->root = root; |
cc31edce | 1779 | init_cgroup_housekeeping(cgrp); |
4e96ee8e | 1780 | idr_init(&root->cgroup_idr); |
c6d57f33 | 1781 | |
c6d57f33 PM |
1782 | root->flags = opts->flags; |
1783 | if (opts->release_agent) | |
1784 | strcpy(root->release_agent_path, opts->release_agent); | |
1785 | if (opts->name) | |
1786 | strcpy(root->name, opts->name); | |
2260e7fc | 1787 | if (opts->cpuset_clone_children) |
3dd06ffa | 1788 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
c6d57f33 PM |
1789 | } |
1790 | ||
8ab456ac | 1791 | static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) |
2c6ab6d2 | 1792 | { |
d427dfeb | 1793 | LIST_HEAD(tmp_links); |
3dd06ffa | 1794 | struct cgroup *root_cgrp = &root->cgrp; |
a14c6874 | 1795 | struct cftype *base_files; |
d427dfeb | 1796 | struct css_set *cset; |
d427dfeb | 1797 | int i, ret; |
2c6ab6d2 | 1798 | |
d427dfeb | 1799 | lockdep_assert_held(&cgroup_mutex); |
c6d57f33 | 1800 | |
cf780b7d | 1801 | ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
d427dfeb | 1802 | if (ret < 0) |
2bd59d48 | 1803 | goto out; |
d427dfeb | 1804 | root_cgrp->id = ret; |
c6d57f33 | 1805 | |
2aad2a86 TH |
1806 | ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, |
1807 | GFP_KERNEL); | |
9d755d33 TH |
1808 | if (ret) |
1809 | goto out; | |
1810 | ||
d427dfeb | 1811 | /* |
96d365e0 | 1812 | * We're accessing css_set_count without locking css_set_rwsem here, |
d427dfeb TH |
1813 | * but that's OK - it can only be increased by someone holding |
1814 | * cgroup_lock, and that's us. The worst that can happen is that we | |
1815 | * have some link structures left over | |
1816 | */ | |
1817 | ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); | |
1818 | if (ret) | |
9d755d33 | 1819 | goto cancel_ref; |
ddbcc7e8 | 1820 | |
985ed670 | 1821 | ret = cgroup_init_root_id(root); |
ddbcc7e8 | 1822 | if (ret) |
9d755d33 | 1823 | goto cancel_ref; |
ddbcc7e8 | 1824 | |
2bd59d48 TH |
1825 | root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
1826 | KERNFS_ROOT_CREATE_DEACTIVATED, | |
1827 | root_cgrp); | |
1828 | if (IS_ERR(root->kf_root)) { | |
1829 | ret = PTR_ERR(root->kf_root); | |
1830 | goto exit_root_id; | |
1831 | } | |
1832 | root_cgrp->kn = root->kf_root->kn; | |
ddbcc7e8 | 1833 | |
a14c6874 TH |
1834 | if (root == &cgrp_dfl_root) |
1835 | base_files = cgroup_dfl_base_files; | |
1836 | else | |
1837 | base_files = cgroup_legacy_base_files; | |
1838 | ||
1839 | ret = cgroup_addrm_files(root_cgrp, base_files, true); | |
d427dfeb | 1840 | if (ret) |
2bd59d48 | 1841 | goto destroy_root; |
ddbcc7e8 | 1842 | |
5df36032 | 1843 | ret = rebind_subsystems(root, ss_mask); |
d427dfeb | 1844 | if (ret) |
2bd59d48 | 1845 | goto destroy_root; |
ddbcc7e8 | 1846 | |
d427dfeb TH |
1847 | /* |
1848 | * There must be no failure case after here, since rebinding takes | |
1849 | * care of subsystems' refcounts, which are explicitly dropped in | |
1850 | * the failure exit path. | |
1851 | */ | |
1852 | list_add(&root->root_list, &cgroup_roots); | |
1853 | cgroup_root_count++; | |
0df6a63f | 1854 | |
d427dfeb | 1855 | /* |
3dd06ffa | 1856 | * Link the root cgroup in this hierarchy into all the css_set |
d427dfeb TH |
1857 | * objects. |
1858 | */ | |
96d365e0 | 1859 | down_write(&css_set_rwsem); |
d427dfeb TH |
1860 | hash_for_each(css_set_table, i, cset, hlist) |
1861 | link_css_set(&tmp_links, cset, root_cgrp); | |
96d365e0 | 1862 | up_write(&css_set_rwsem); |
ddbcc7e8 | 1863 | |
d5c419b6 | 1864 | BUG_ON(!list_empty(&root_cgrp->self.children)); |
3c9c825b | 1865 | BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
ddbcc7e8 | 1866 | |
2bd59d48 | 1867 | kernfs_activate(root_cgrp->kn); |
d427dfeb | 1868 | ret = 0; |
2bd59d48 | 1869 | goto out; |
d427dfeb | 1870 | |
2bd59d48 TH |
1871 | destroy_root: |
1872 | kernfs_destroy_root(root->kf_root); | |
1873 | root->kf_root = NULL; | |
1874 | exit_root_id: | |
d427dfeb | 1875 | cgroup_exit_root_id(root); |
9d755d33 | 1876 | cancel_ref: |
9a1049da | 1877 | percpu_ref_exit(&root_cgrp->self.refcnt); |
2bd59d48 | 1878 | out: |
d427dfeb TH |
1879 | free_cgrp_cset_links(&tmp_links); |
1880 | return ret; | |
ddbcc7e8 PM |
1881 | } |
1882 | ||
f7e83571 | 1883 | static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
ddbcc7e8 | 1884 | int flags, const char *unused_dev_name, |
f7e83571 | 1885 | void *data) |
ddbcc7e8 | 1886 | { |
3a32bd72 | 1887 | struct super_block *pinned_sb = NULL; |
970317aa | 1888 | struct cgroup_subsys *ss; |
3dd06ffa | 1889 | struct cgroup_root *root; |
ddbcc7e8 | 1890 | struct cgroup_sb_opts opts; |
2bd59d48 | 1891 | struct dentry *dentry; |
8e30e2b8 | 1892 | int ret; |
970317aa | 1893 | int i; |
c6b3d5bc | 1894 | bool new_sb; |
ddbcc7e8 | 1895 | |
56fde9e0 TH |
1896 | /* |
1897 | * The first time anyone tries to mount a cgroup, enable the list | |
1898 | * linking each css_set to its tasks and fix up all existing tasks. | |
1899 | */ | |
1900 | if (!use_task_css_set_links) | |
1901 | cgroup_enable_task_cg_lists(); | |
e37a06f1 | 1902 | |
aae8aab4 | 1903 | mutex_lock(&cgroup_mutex); |
8e30e2b8 TH |
1904 | |
1905 | /* First find the desired set of subsystems */ | |
ddbcc7e8 | 1906 | ret = parse_cgroupfs_options(data, &opts); |
c6d57f33 | 1907 | if (ret) |
8e30e2b8 | 1908 | goto out_unlock; |
a015edd2 | 1909 | |
2bd59d48 | 1910 | /* look for a matching existing root */ |
7b9a6ba5 | 1911 | if (opts.flags & CGRP_ROOT_SANE_BEHAVIOR) { |
a2dd4247 TH |
1912 | cgrp_dfl_root_visible = true; |
1913 | root = &cgrp_dfl_root; | |
1914 | cgroup_get(&root->cgrp); | |
1915 | ret = 0; | |
1916 | goto out_unlock; | |
ddbcc7e8 PM |
1917 | } |
1918 | ||
970317aa LZ |
1919 | /* |
1920 | * Destruction of cgroup root is asynchronous, so subsystems may | |
1921 | * still be dying after the previous unmount. Let's drain the | |
1922 | * dying subsystems. We just need to ensure that the ones | |
1923 | * unmounted previously finish dying and don't care about new ones | |
1924 | * starting. Testing ref liveliness is good enough. | |
1925 | */ | |
1926 | for_each_subsys(ss, i) { | |
1927 | if (!(opts.subsys_mask & (1 << i)) || | |
1928 | ss->root == &cgrp_dfl_root) | |
1929 | continue; | |
1930 | ||
1931 | if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { | |
1932 | mutex_unlock(&cgroup_mutex); | |
1933 | msleep(10); | |
1934 | ret = restart_syscall(); | |
1935 | goto out_free; | |
1936 | } | |
1937 | cgroup_put(&ss->root->cgrp); | |
1938 | } | |
1939 | ||
985ed670 | 1940 | for_each_root(root) { |
2bd59d48 | 1941 | bool name_match = false; |
3126121f | 1942 | |
3dd06ffa | 1943 | if (root == &cgrp_dfl_root) |
985ed670 | 1944 | continue; |
3126121f | 1945 | |
cf5d5941 | 1946 | /* |
2bd59d48 TH |
1947 | * If we asked for a name then it must match. Also, if |
1948 | * name matches but sybsys_mask doesn't, we should fail. | |
1949 | * Remember whether name matched. | |
cf5d5941 | 1950 | */ |
2bd59d48 TH |
1951 | if (opts.name) { |
1952 | if (strcmp(opts.name, root->name)) | |
1953 | continue; | |
1954 | name_match = true; | |
1955 | } | |
ddbcc7e8 | 1956 | |
c6d57f33 | 1957 | /* |
2bd59d48 TH |
1958 | * If we asked for subsystems (or explicitly for no |
1959 | * subsystems) then they must match. | |
c6d57f33 | 1960 | */ |
2bd59d48 | 1961 | if ((opts.subsys_mask || opts.none) && |
f392e51c | 1962 | (opts.subsys_mask != root->subsys_mask)) { |
2bd59d48 TH |
1963 | if (!name_match) |
1964 | continue; | |
1965 | ret = -EBUSY; | |
1966 | goto out_unlock; | |
1967 | } | |
873fe09e | 1968 | |
7b9a6ba5 TH |
1969 | if (root->flags ^ opts.flags) |
1970 | pr_warn("new mount options do not match the existing superblock, will be ignored\n"); | |
ddbcc7e8 | 1971 | |
776f02fa | 1972 | /* |
3a32bd72 LZ |
1973 | * We want to reuse @root whose lifetime is governed by its |
1974 | * ->cgrp. Let's check whether @root is alive and keep it | |
1975 | * that way. As cgroup_kill_sb() can happen anytime, we | |
1976 | * want to block it by pinning the sb so that @root doesn't | |
1977 | * get killed before mount is complete. | |
1978 | * | |
1979 | * With the sb pinned, tryget_live can reliably indicate | |
1980 | * whether @root can be reused. If it's being killed, | |
1981 | * drain it. We can use wait_queue for the wait but this | |
1982 | * path is super cold. Let's just sleep a bit and retry. | |
776f02fa | 1983 | */ |
3a32bd72 LZ |
1984 | pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
1985 | if (IS_ERR(pinned_sb) || | |
1986 | !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { | |
776f02fa | 1987 | mutex_unlock(&cgroup_mutex); |
3a32bd72 LZ |
1988 | if (!IS_ERR_OR_NULL(pinned_sb)) |
1989 | deactivate_super(pinned_sb); | |
776f02fa | 1990 | msleep(10); |
a015edd2 TH |
1991 | ret = restart_syscall(); |
1992 | goto out_free; | |
776f02fa | 1993 | } |
ddbcc7e8 | 1994 | |
776f02fa | 1995 | ret = 0; |
2bd59d48 | 1996 | goto out_unlock; |
ddbcc7e8 | 1997 | } |
ddbcc7e8 | 1998 | |
817929ec | 1999 | /* |
172a2c06 TH |
2000 | * No such thing, create a new one. name= matching without subsys |
2001 | * specification is allowed for already existing hierarchies but we | |
2002 | * can't create new one without subsys specification. | |
817929ec | 2003 | */ |
172a2c06 TH |
2004 | if (!opts.subsys_mask && !opts.none) { |
2005 | ret = -EINVAL; | |
2006 | goto out_unlock; | |
817929ec | 2007 | } |
817929ec | 2008 | |
172a2c06 TH |
2009 | root = kzalloc(sizeof(*root), GFP_KERNEL); |
2010 | if (!root) { | |
2011 | ret = -ENOMEM; | |
2bd59d48 | 2012 | goto out_unlock; |
839ec545 | 2013 | } |
e5f6a860 | 2014 | |
172a2c06 TH |
2015 | init_cgroup_root(root, &opts); |
2016 | ||
35585573 | 2017 | ret = cgroup_setup_root(root, opts.subsys_mask); |
2bd59d48 TH |
2018 | if (ret) |
2019 | cgroup_free_root(root); | |
fa3ca07e | 2020 | |
8e30e2b8 | 2021 | out_unlock: |
ddbcc7e8 | 2022 | mutex_unlock(&cgroup_mutex); |
a015edd2 | 2023 | out_free: |
c6d57f33 PM |
2024 | kfree(opts.release_agent); |
2025 | kfree(opts.name); | |
03b1cde6 | 2026 | |
2bd59d48 | 2027 | if (ret) |
8e30e2b8 | 2028 | return ERR_PTR(ret); |
2bd59d48 | 2029 | |
c9482a5b JZ |
2030 | dentry = kernfs_mount(fs_type, flags, root->kf_root, |
2031 | CGROUP_SUPER_MAGIC, &new_sb); | |
c6b3d5bc | 2032 | if (IS_ERR(dentry) || !new_sb) |
3dd06ffa | 2033 | cgroup_put(&root->cgrp); |
3a32bd72 LZ |
2034 | |
2035 | /* | |
2036 | * If @pinned_sb, we're reusing an existing root and holding an | |
2037 | * extra ref on its sb. Mount is complete. Put the extra ref. | |
2038 | */ | |
2039 | if (pinned_sb) { | |
2040 | WARN_ON(new_sb); | |
2041 | deactivate_super(pinned_sb); | |
2042 | } | |
2043 | ||
2bd59d48 TH |
2044 | return dentry; |
2045 | } | |
2046 | ||
2047 | static void cgroup_kill_sb(struct super_block *sb) | |
2048 | { | |
2049 | struct kernfs_root *kf_root = kernfs_root_from_sb(sb); | |
3dd06ffa | 2050 | struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
2bd59d48 | 2051 | |
9d755d33 TH |
2052 | /* |
2053 | * If @root doesn't have any mounts or children, start killing it. | |
2054 | * This prevents new mounts by disabling percpu_ref_tryget_live(). | |
2055 | * cgroup_mount() may wait for @root's release. | |
1f779fb2 LZ |
2056 | * |
2057 | * And don't kill the default root. | |
9d755d33 | 2058 | */ |
3c606d35 | 2059 | if (!list_empty(&root->cgrp.self.children) || |
1f779fb2 | 2060 | root == &cgrp_dfl_root) |
9d755d33 TH |
2061 | cgroup_put(&root->cgrp); |
2062 | else | |
2063 | percpu_ref_kill(&root->cgrp.self.refcnt); | |
2064 | ||
2bd59d48 | 2065 | kernfs_kill_sb(sb); |
ddbcc7e8 PM |
2066 | } |
2067 | ||
2068 | static struct file_system_type cgroup_fs_type = { | |
2069 | .name = "cgroup", | |
f7e83571 | 2070 | .mount = cgroup_mount, |
ddbcc7e8 PM |
2071 | .kill_sb = cgroup_kill_sb, |
2072 | }; | |
2073 | ||
857a2beb | 2074 | /** |
913ffdb5 | 2075 | * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
857a2beb | 2076 | * @task: target task |
857a2beb TH |
2077 | * @buf: the buffer to write the path into |
2078 | * @buflen: the length of the buffer | |
2079 | * | |
913ffdb5 TH |
2080 | * Determine @task's cgroup on the first (the one with the lowest non-zero |
2081 | * hierarchy_id) cgroup hierarchy and copy its path into @buf. This | |
2082 | * function grabs cgroup_mutex and shouldn't be used inside locks used by | |
2083 | * cgroup controller callbacks. | |
2084 | * | |
e61734c5 | 2085 | * Return value is the same as kernfs_path(). |
857a2beb | 2086 | */ |
e61734c5 | 2087 | char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
857a2beb | 2088 | { |
3dd06ffa | 2089 | struct cgroup_root *root; |
913ffdb5 | 2090 | struct cgroup *cgrp; |
e61734c5 TH |
2091 | int hierarchy_id = 1; |
2092 | char *path = NULL; | |
857a2beb TH |
2093 | |
2094 | mutex_lock(&cgroup_mutex); | |
96d365e0 | 2095 | down_read(&css_set_rwsem); |
857a2beb | 2096 | |
913ffdb5 TH |
2097 | root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
2098 | ||
857a2beb TH |
2099 | if (root) { |
2100 | cgrp = task_cgroup_from_root(task, root); | |
e61734c5 | 2101 | path = cgroup_path(cgrp, buf, buflen); |
913ffdb5 TH |
2102 | } else { |
2103 | /* if no hierarchy exists, everyone is in "/" */ | |
e61734c5 TH |
2104 | if (strlcpy(buf, "/", buflen) < buflen) |
2105 | path = buf; | |
857a2beb TH |
2106 | } |
2107 | ||
96d365e0 | 2108 | up_read(&css_set_rwsem); |
857a2beb | 2109 | mutex_unlock(&cgroup_mutex); |
e61734c5 | 2110 | return path; |
857a2beb | 2111 | } |
913ffdb5 | 2112 | EXPORT_SYMBOL_GPL(task_cgroup_path); |
857a2beb | 2113 | |
b3dc094e | 2114 | /* used to track tasks and other necessary states during migration */ |
2f7ee569 | 2115 | struct cgroup_taskset { |
b3dc094e TH |
2116 | /* the src and dst cset list running through cset->mg_node */ |
2117 | struct list_head src_csets; | |
2118 | struct list_head dst_csets; | |
2119 | ||
2120 | /* | |
2121 | * Fields for cgroup_taskset_*() iteration. | |
2122 | * | |
2123 | * Before migration is committed, the target migration tasks are on | |
2124 | * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of | |
2125 | * the csets on ->dst_csets. ->csets point to either ->src_csets | |
2126 | * or ->dst_csets depending on whether migration is committed. | |
2127 | * | |
2128 | * ->cur_csets and ->cur_task point to the current task position | |
2129 | * during iteration. | |
2130 | */ | |
2131 | struct list_head *csets; | |
2132 | struct css_set *cur_cset; | |
2133 | struct task_struct *cur_task; | |
2f7ee569 TH |
2134 | }; |
2135 | ||
2136 | /** | |
2137 | * cgroup_taskset_first - reset taskset and return the first task | |
2138 | * @tset: taskset of interest | |
2139 | * | |
2140 | * @tset iteration is initialized and the first task is returned. | |
2141 | */ | |
2142 | struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset) | |
2143 | { | |
b3dc094e TH |
2144 | tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
2145 | tset->cur_task = NULL; | |
2146 | ||
2147 | return cgroup_taskset_next(tset); | |
2f7ee569 | 2148 | } |
2f7ee569 TH |
2149 | |
2150 | /** | |
2151 | * cgroup_taskset_next - iterate to the next task in taskset | |
2152 | * @tset: taskset of interest | |
2153 | * | |
2154 | * Return the next task in @tset. Iteration must have been initialized | |
2155 | * with cgroup_taskset_first(). | |
2156 | */ | |
2157 | struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset) | |
2158 | { | |
b3dc094e TH |
2159 | struct css_set *cset = tset->cur_cset; |
2160 | struct task_struct *task = tset->cur_task; | |
2f7ee569 | 2161 | |
b3dc094e TH |
2162 | while (&cset->mg_node != tset->csets) { |
2163 | if (!task) | |
2164 | task = list_first_entry(&cset->mg_tasks, | |
2165 | struct task_struct, cg_list); | |
2166 | else | |
2167 | task = list_next_entry(task, cg_list); | |
2f7ee569 | 2168 | |
b3dc094e TH |
2169 | if (&task->cg_list != &cset->mg_tasks) { |
2170 | tset->cur_cset = cset; | |
2171 | tset->cur_task = task; | |
2172 | return task; | |
2173 | } | |
2f7ee569 | 2174 | |
b3dc094e TH |
2175 | cset = list_next_entry(cset, mg_node); |
2176 | task = NULL; | |
2177 | } | |
2f7ee569 | 2178 | |
b3dc094e | 2179 | return NULL; |
2f7ee569 | 2180 | } |
2f7ee569 | 2181 | |
cb0f1fe9 | 2182 | /** |
74a1166d | 2183 | * cgroup_task_migrate - move a task from one cgroup to another. |
60106946 | 2184 | * @old_cgrp: the cgroup @tsk is being migrated from |
cb0f1fe9 TH |
2185 | * @tsk: the task being migrated |
2186 | * @new_cset: the new css_set @tsk is being attached to | |
74a1166d | 2187 | * |
cb0f1fe9 | 2188 | * Must be called with cgroup_mutex, threadgroup and css_set_rwsem locked. |
74a1166d | 2189 | */ |
5abb8855 TH |
2190 | static void cgroup_task_migrate(struct cgroup *old_cgrp, |
2191 | struct task_struct *tsk, | |
2192 | struct css_set *new_cset) | |
74a1166d | 2193 | { |
5abb8855 | 2194 | struct css_set *old_cset; |
74a1166d | 2195 | |
cb0f1fe9 TH |
2196 | lockdep_assert_held(&cgroup_mutex); |
2197 | lockdep_assert_held(&css_set_rwsem); | |
2198 | ||
74a1166d | 2199 | /* |
1ed13287 TH |
2200 | * We are synchronized through cgroup_threadgroup_rwsem against |
2201 | * PF_EXITING setting such that we can't race against cgroup_exit() | |
2202 | * changing the css_set to init_css_set and dropping the old one. | |
74a1166d | 2203 | */ |
c84cdf75 | 2204 | WARN_ON_ONCE(tsk->flags & PF_EXITING); |
a8ad805c | 2205 | old_cset = task_css_set(tsk); |
74a1166d | 2206 | |
b3dc094e | 2207 | get_css_set(new_cset); |
5abb8855 | 2208 | rcu_assign_pointer(tsk->cgroups, new_cset); |
74a1166d | 2209 | |
1b9aba49 TH |
2210 | /* |
2211 | * Use move_tail so that cgroup_taskset_first() still returns the | |
2212 | * leader after migration. This works because cgroup_migrate() | |
2213 | * ensures that the dst_cset of the leader is the first on the | |
2214 | * tset's dst_csets list. | |
2215 | */ | |
2216 | list_move_tail(&tsk->cg_list, &new_cset->mg_tasks); | |
74a1166d BB |
2217 | |
2218 | /* | |
5abb8855 TH |
2219 | * We just gained a reference on old_cset by taking it from the |
2220 | * task. As trading it for new_cset is protected by cgroup_mutex, | |
2221 | * we're safe to drop it here; it will be freed under RCU. | |
74a1166d | 2222 | */ |
a25eb52e | 2223 | put_css_set_locked(old_cset); |
74a1166d BB |
2224 | } |
2225 | ||
a043e3b2 | 2226 | /** |
1958d2d5 TH |
2227 | * cgroup_migrate_finish - cleanup after attach |
2228 | * @preloaded_csets: list of preloaded css_sets | |
74a1166d | 2229 | * |
1958d2d5 TH |
2230 | * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
2231 | * those functions for details. | |
74a1166d | 2232 | */ |
1958d2d5 | 2233 | static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
74a1166d | 2234 | { |
1958d2d5 | 2235 | struct css_set *cset, *tmp_cset; |
74a1166d | 2236 | |
1958d2d5 TH |
2237 | lockdep_assert_held(&cgroup_mutex); |
2238 | ||
2239 | down_write(&css_set_rwsem); | |
2240 | list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { | |
2241 | cset->mg_src_cgrp = NULL; | |
2242 | cset->mg_dst_cset = NULL; | |
2243 | list_del_init(&cset->mg_preload_node); | |
a25eb52e | 2244 | put_css_set_locked(cset); |
1958d2d5 TH |
2245 | } |
2246 | up_write(&css_set_rwsem); | |
2247 | } | |
2248 | ||
2249 | /** | |
2250 | * cgroup_migrate_add_src - add a migration source css_set | |
2251 | * @src_cset: the source css_set to add | |
2252 | * @dst_cgrp: the destination cgroup | |
2253 | * @preloaded_csets: list of preloaded css_sets | |
2254 | * | |
2255 | * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin | |
2256 | * @src_cset and add it to @preloaded_csets, which should later be cleaned | |
2257 | * up by cgroup_migrate_finish(). | |
2258 | * | |
1ed13287 TH |
2259 | * This function may be called without holding cgroup_threadgroup_rwsem |
2260 | * even if the target is a process. Threads may be created and destroyed | |
2261 | * but as long as cgroup_mutex is not dropped, no new css_set can be put | |
2262 | * into play and the preloaded css_sets are guaranteed to cover all | |
2263 | * migrations. | |
1958d2d5 TH |
2264 | */ |
2265 | static void cgroup_migrate_add_src(struct css_set *src_cset, | |
2266 | struct cgroup *dst_cgrp, | |
2267 | struct list_head *preloaded_csets) | |
2268 | { | |
2269 | struct cgroup *src_cgrp; | |
2270 | ||
2271 | lockdep_assert_held(&cgroup_mutex); | |
2272 | lockdep_assert_held(&css_set_rwsem); | |
2273 | ||
2274 | src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); | |
2275 | ||
1958d2d5 TH |
2276 | if (!list_empty(&src_cset->mg_preload_node)) |
2277 | return; | |
2278 | ||
2279 | WARN_ON(src_cset->mg_src_cgrp); | |
2280 | WARN_ON(!list_empty(&src_cset->mg_tasks)); | |
2281 | WARN_ON(!list_empty(&src_cset->mg_node)); | |
2282 | ||
2283 | src_cset->mg_src_cgrp = src_cgrp; | |
2284 | get_css_set(src_cset); | |
2285 | list_add(&src_cset->mg_preload_node, preloaded_csets); | |
2286 | } | |
2287 | ||
2288 | /** | |
2289 | * cgroup_migrate_prepare_dst - prepare destination css_sets for migration | |
f817de98 | 2290 | * @dst_cgrp: the destination cgroup (may be %NULL) |
1958d2d5 TH |
2291 | * @preloaded_csets: list of preloaded source css_sets |
2292 | * | |
2293 | * Tasks are about to be moved to @dst_cgrp and all the source css_sets | |
2294 | * have been preloaded to @preloaded_csets. This function looks up and | |
f817de98 TH |
2295 | * pins all destination css_sets, links each to its source, and append them |
2296 | * to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each | |
2297 | * source css_set is assumed to be its cgroup on the default hierarchy. | |
1958d2d5 TH |
2298 | * |
2299 | * This function must be called after cgroup_migrate_add_src() has been | |
2300 | * called on each migration source css_set. After migration is performed | |
2301 | * using cgroup_migrate(), cgroup_migrate_finish() must be called on | |
2302 | * @preloaded_csets. | |
2303 | */ | |
2304 | static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp, | |
2305 | struct list_head *preloaded_csets) | |
2306 | { | |
2307 | LIST_HEAD(csets); | |
f817de98 | 2308 | struct css_set *src_cset, *tmp_cset; |
1958d2d5 TH |
2309 | |
2310 | lockdep_assert_held(&cgroup_mutex); | |
2311 | ||
f8f22e53 TH |
2312 | /* |
2313 | * Except for the root, child_subsys_mask must be zero for a cgroup | |
2314 | * with tasks so that child cgroups don't compete against tasks. | |
2315 | */ | |
d51f39b0 | 2316 | if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) && |
f8f22e53 TH |
2317 | dst_cgrp->child_subsys_mask) |
2318 | return -EBUSY; | |
2319 | ||
1958d2d5 | 2320 | /* look up the dst cset for each src cset and link it to src */ |
f817de98 | 2321 | list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) { |
1958d2d5 TH |
2322 | struct css_set *dst_cset; |
2323 | ||
f817de98 TH |
2324 | dst_cset = find_css_set(src_cset, |
2325 | dst_cgrp ?: src_cset->dfl_cgrp); | |
1958d2d5 TH |
2326 | if (!dst_cset) |
2327 | goto err; | |
2328 | ||
2329 | WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); | |
f817de98 TH |
2330 | |
2331 | /* | |
2332 | * If src cset equals dst, it's noop. Drop the src. | |
2333 | * cgroup_migrate() will skip the cset too. Note that we | |
2334 | * can't handle src == dst as some nodes are used by both. | |
2335 | */ | |
2336 | if (src_cset == dst_cset) { | |
2337 | src_cset->mg_src_cgrp = NULL; | |
2338 | list_del_init(&src_cset->mg_preload_node); | |
a25eb52e ZL |
2339 | put_css_set(src_cset); |
2340 | put_css_set(dst_cset); | |
f817de98 TH |
2341 | continue; |
2342 | } | |
2343 | ||
1958d2d5 TH |
2344 | src_cset->mg_dst_cset = dst_cset; |
2345 | ||
2346 | if (list_empty(&dst_cset->mg_preload_node)) | |
2347 | list_add(&dst_cset->mg_preload_node, &csets); | |
2348 | else | |
a25eb52e | 2349 | put_css_set(dst_cset); |
1958d2d5 TH |
2350 | } |
2351 | ||
f817de98 | 2352 | list_splice_tail(&csets, preloaded_csets); |
1958d2d5 TH |
2353 | return 0; |
2354 | err: | |
2355 | cgroup_migrate_finish(&csets); | |
2356 | return -ENOMEM; | |
2357 | } | |
2358 | ||
2359 | /** | |
2360 | * cgroup_migrate - migrate a process or task to a cgroup | |
2361 | * @cgrp: the destination cgroup | |
2362 | * @leader: the leader of the process or the task to migrate | |
2363 | * @threadgroup: whether @leader points to the whole process or a single task | |
2364 | * | |
2365 | * Migrate a process or task denoted by @leader to @cgrp. If migrating a | |
1ed13287 | 2366 | * process, the caller must be holding cgroup_threadgroup_rwsem. The |
1958d2d5 TH |
2367 | * caller is also responsible for invoking cgroup_migrate_add_src() and |
2368 | * cgroup_migrate_prepare_dst() on the targets before invoking this | |
2369 | * function and following up with cgroup_migrate_finish(). | |
2370 | * | |
2371 | * As long as a controller's ->can_attach() doesn't fail, this function is | |
2372 | * guaranteed to succeed. This means that, excluding ->can_attach() | |
2373 | * failure, when migrating multiple targets, the success or failure can be | |
2374 | * decided for all targets by invoking group_migrate_prepare_dst() before | |
2375 | * actually starting migrating. | |
2376 | */ | |
2377 | static int cgroup_migrate(struct cgroup *cgrp, struct task_struct *leader, | |
2378 | bool threadgroup) | |
74a1166d | 2379 | { |
b3dc094e TH |
2380 | struct cgroup_taskset tset = { |
2381 | .src_csets = LIST_HEAD_INIT(tset.src_csets), | |
2382 | .dst_csets = LIST_HEAD_INIT(tset.dst_csets), | |
2383 | .csets = &tset.src_csets, | |
2384 | }; | |
1c6727af | 2385 | struct cgroup_subsys_state *css, *failed_css = NULL; |
b3dc094e TH |
2386 | struct css_set *cset, *tmp_cset; |
2387 | struct task_struct *task, *tmp_task; | |
2388 | int i, ret; | |
74a1166d | 2389 | |
fb5d2b4c MSB |
2390 | /* |
2391 | * Prevent freeing of tasks while we take a snapshot. Tasks that are | |
2392 | * already PF_EXITING could be freed from underneath us unless we | |
2393 | * take an rcu_read_lock. | |
2394 | */ | |
b3dc094e | 2395 | down_write(&css_set_rwsem); |
fb5d2b4c | 2396 | rcu_read_lock(); |
9db8de37 | 2397 | task = leader; |
74a1166d | 2398 | do { |
9db8de37 TH |
2399 | /* @task either already exited or can't exit until the end */ |
2400 | if (task->flags & PF_EXITING) | |
ea84753c | 2401 | goto next; |
134d3373 | 2402 | |
eaf797ab TH |
2403 | /* leave @task alone if post_fork() hasn't linked it yet */ |
2404 | if (list_empty(&task->cg_list)) | |
ea84753c | 2405 | goto next; |
cd3d0952 | 2406 | |
b3dc094e | 2407 | cset = task_css_set(task); |
1958d2d5 | 2408 | if (!cset->mg_src_cgrp) |
ea84753c | 2409 | goto next; |
b3dc094e | 2410 | |
61d1d219 | 2411 | /* |
1b9aba49 TH |
2412 | * cgroup_taskset_first() must always return the leader. |
2413 | * Take care to avoid disturbing the ordering. | |
61d1d219 | 2414 | */ |
1b9aba49 TH |
2415 | list_move_tail(&task->cg_list, &cset->mg_tasks); |
2416 | if (list_empty(&cset->mg_node)) | |
2417 | list_add_tail(&cset->mg_node, &tset.src_csets); | |
2418 | if (list_empty(&cset->mg_dst_cset->mg_node)) | |
2419 | list_move_tail(&cset->mg_dst_cset->mg_node, | |
2420 | &tset.dst_csets); | |
ea84753c | 2421 | next: |
081aa458 LZ |
2422 | if (!threadgroup) |
2423 | break; | |
9db8de37 | 2424 | } while_each_thread(leader, task); |
fb5d2b4c | 2425 | rcu_read_unlock(); |
b3dc094e | 2426 | up_write(&css_set_rwsem); |
74a1166d | 2427 | |
134d3373 | 2428 | /* methods shouldn't be called if no task is actually migrating */ |
b3dc094e TH |
2429 | if (list_empty(&tset.src_csets)) |
2430 | return 0; | |
134d3373 | 2431 | |
1958d2d5 | 2432 | /* check that we can legitimately attach to the cgroup */ |
aec3dfcb | 2433 | for_each_e_css(css, i, cgrp) { |
1c6727af | 2434 | if (css->ss->can_attach) { |
9db8de37 TH |
2435 | ret = css->ss->can_attach(css, &tset); |
2436 | if (ret) { | |
1c6727af | 2437 | failed_css = css; |
74a1166d BB |
2438 | goto out_cancel_attach; |
2439 | } | |
2440 | } | |
74a1166d BB |
2441 | } |
2442 | ||
2443 | /* | |
1958d2d5 TH |
2444 | * Now that we're guaranteed success, proceed to move all tasks to |
2445 | * the new cgroup. There are no failure cases after here, so this | |
2446 | * is the commit point. | |
74a1166d | 2447 | */ |
cb0f1fe9 | 2448 | down_write(&css_set_rwsem); |
b3dc094e TH |
2449 | list_for_each_entry(cset, &tset.src_csets, mg_node) { |
2450 | list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) | |
2451 | cgroup_task_migrate(cset->mg_src_cgrp, task, | |
2452 | cset->mg_dst_cset); | |
74a1166d | 2453 | } |
cb0f1fe9 | 2454 | up_write(&css_set_rwsem); |
74a1166d BB |
2455 | |
2456 | /* | |
1958d2d5 TH |
2457 | * Migration is committed, all target tasks are now on dst_csets. |
2458 | * Nothing is sensitive to fork() after this point. Notify | |
2459 | * controllers that migration is complete. | |
74a1166d | 2460 | */ |
1958d2d5 | 2461 | tset.csets = &tset.dst_csets; |
74a1166d | 2462 | |
aec3dfcb | 2463 | for_each_e_css(css, i, cgrp) |
1c6727af TH |
2464 | if (css->ss->attach) |
2465 | css->ss->attach(css, &tset); | |
74a1166d | 2466 | |
9db8de37 | 2467 | ret = 0; |
b3dc094e TH |
2468 | goto out_release_tset; |
2469 | ||
74a1166d | 2470 | out_cancel_attach: |
aec3dfcb | 2471 | for_each_e_css(css, i, cgrp) { |
b3dc094e TH |
2472 | if (css == failed_css) |
2473 | break; | |
2474 | if (css->ss->cancel_attach) | |
2475 | css->ss->cancel_attach(css, &tset); | |
74a1166d | 2476 | } |
b3dc094e TH |
2477 | out_release_tset: |
2478 | down_write(&css_set_rwsem); | |
2479 | list_splice_init(&tset.dst_csets, &tset.src_csets); | |
2480 | list_for_each_entry_safe(cset, tmp_cset, &tset.src_csets, mg_node) { | |
1b9aba49 | 2481 | list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
b3dc094e | 2482 | list_del_init(&cset->mg_node); |
b3dc094e TH |
2483 | } |
2484 | up_write(&css_set_rwsem); | |
9db8de37 | 2485 | return ret; |
74a1166d BB |
2486 | } |
2487 | ||
1958d2d5 TH |
2488 | /** |
2489 | * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup | |
2490 | * @dst_cgrp: the cgroup to attach to | |
2491 | * @leader: the task or the leader of the threadgroup to be attached | |
2492 | * @threadgroup: attach the whole threadgroup? | |
2493 | * | |
1ed13287 | 2494 | * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
1958d2d5 TH |
2495 | */ |
2496 | static int cgroup_attach_task(struct cgroup *dst_cgrp, | |
2497 | struct task_struct *leader, bool threadgroup) | |
2498 | { | |
2499 | LIST_HEAD(preloaded_csets); | |
2500 | struct task_struct *task; | |
2501 | int ret; | |
2502 | ||
2503 | /* look up all src csets */ | |
2504 | down_read(&css_set_rwsem); | |
2505 | rcu_read_lock(); | |
2506 | task = leader; | |
2507 | do { | |
2508 | cgroup_migrate_add_src(task_css_set(task), dst_cgrp, | |
2509 | &preloaded_csets); | |
2510 | if (!threadgroup) | |
2511 | break; | |
2512 | } while_each_thread(leader, task); | |
2513 | rcu_read_unlock(); | |
2514 | up_read(&css_set_rwsem); | |
2515 | ||
2516 | /* prepare dst csets and commit */ | |
2517 | ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets); | |
2518 | if (!ret) | |
2519 | ret = cgroup_migrate(dst_cgrp, leader, threadgroup); | |
2520 | ||
2521 | cgroup_migrate_finish(&preloaded_csets); | |
2522 | return ret; | |
74a1166d BB |
2523 | } |
2524 | ||
187fe840 TH |
2525 | static int cgroup_procs_write_permission(struct task_struct *task, |
2526 | struct cgroup *dst_cgrp, | |
2527 | struct kernfs_open_file *of) | |
dedf22e9 TH |
2528 | { |
2529 | const struct cred *cred = current_cred(); | |
2530 | const struct cred *tcred = get_task_cred(task); | |
2531 | int ret = 0; | |
2532 | ||
2533 | /* | |
2534 | * even if we're attaching all tasks in the thread group, we only | |
2535 | * need to check permissions on one of them. | |
2536 | */ | |
2537 | if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && | |
2538 | !uid_eq(cred->euid, tcred->uid) && | |
2539 | !uid_eq(cred->euid, tcred->suid)) | |
2540 | ret = -EACCES; | |
2541 | ||
187fe840 TH |
2542 | if (!ret && cgroup_on_dfl(dst_cgrp)) { |
2543 | struct super_block *sb = of->file->f_path.dentry->d_sb; | |
2544 | struct cgroup *cgrp; | |
2545 | struct inode *inode; | |
2546 | ||
2547 | down_read(&css_set_rwsem); | |
2548 | cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); | |
2549 | up_read(&css_set_rwsem); | |
2550 | ||
2551 | while (!cgroup_is_descendant(dst_cgrp, cgrp)) | |
2552 | cgrp = cgroup_parent(cgrp); | |
2553 | ||
2554 | ret = -ENOMEM; | |
2555 | inode = kernfs_get_inode(sb, cgrp->procs_kn); | |
2556 | if (inode) { | |
2557 | ret = inode_permission(inode, MAY_WRITE); | |
2558 | iput(inode); | |
2559 | } | |
2560 | } | |
2561 | ||
dedf22e9 TH |
2562 | put_cred(tcred); |
2563 | return ret; | |
2564 | } | |
2565 | ||
74a1166d BB |
2566 | /* |
2567 | * Find the task_struct of the task to attach by vpid and pass it along to the | |
cd3d0952 | 2568 | * function to attach either it or all tasks in its threadgroup. Will lock |
0e1d768f | 2569 | * cgroup_mutex and threadgroup. |
bbcb81d0 | 2570 | */ |
acbef755 TH |
2571 | static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
2572 | size_t nbytes, loff_t off, bool threadgroup) | |
bbcb81d0 | 2573 | { |
bbcb81d0 | 2574 | struct task_struct *tsk; |
e76ecaee | 2575 | struct cgroup *cgrp; |
acbef755 | 2576 | pid_t pid; |
bbcb81d0 PM |
2577 | int ret; |
2578 | ||
acbef755 TH |
2579 | if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
2580 | return -EINVAL; | |
2581 | ||
e76ecaee TH |
2582 | cgrp = cgroup_kn_lock_live(of->kn); |
2583 | if (!cgrp) | |
74a1166d BB |
2584 | return -ENODEV; |
2585 | ||
3014dde7 | 2586 | percpu_down_write(&cgroup_threadgroup_rwsem); |
b78949eb | 2587 | rcu_read_lock(); |
bbcb81d0 | 2588 | if (pid) { |
73507f33 | 2589 | tsk = find_task_by_vpid(pid); |
74a1166d | 2590 | if (!tsk) { |
dd4b0a46 | 2591 | ret = -ESRCH; |
3014dde7 | 2592 | goto out_unlock_rcu; |
bbcb81d0 | 2593 | } |
dedf22e9 | 2594 | } else { |
b78949eb | 2595 | tsk = current; |
dedf22e9 | 2596 | } |
cd3d0952 TH |
2597 | |
2598 | if (threadgroup) | |
b78949eb | 2599 | tsk = tsk->group_leader; |
c4c27fbd MG |
2600 | |
2601 | /* | |
14a40ffc | 2602 | * Workqueue threads may acquire PF_NO_SETAFFINITY and become |
c4c27fbd MG |
2603 | * trapped in a cpuset, or RT worker may be born in a cgroup |
2604 | * with no rt_runtime allocated. Just say no. | |
2605 | */ | |
14a40ffc | 2606 | if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) { |
c4c27fbd | 2607 | ret = -EINVAL; |
3014dde7 | 2608 | goto out_unlock_rcu; |
c4c27fbd MG |
2609 | } |
2610 | ||
b78949eb MSB |
2611 | get_task_struct(tsk); |
2612 | rcu_read_unlock(); | |
2613 | ||
187fe840 | 2614 | ret = cgroup_procs_write_permission(tsk, cgrp, of); |
dedf22e9 TH |
2615 | if (!ret) |
2616 | ret = cgroup_attach_task(cgrp, tsk, threadgroup); | |
081aa458 | 2617 | |
f9f9e7b7 | 2618 | put_task_struct(tsk); |
3014dde7 TH |
2619 | goto out_unlock_threadgroup; |
2620 | ||
2621 | out_unlock_rcu: | |
2622 | rcu_read_unlock(); | |
2623 | out_unlock_threadgroup: | |
2624 | percpu_up_write(&cgroup_threadgroup_rwsem); | |
e76ecaee | 2625 | cgroup_kn_unlock(of->kn); |
acbef755 | 2626 | return ret ?: nbytes; |
bbcb81d0 PM |
2627 | } |
2628 | ||
7ae1bad9 TH |
2629 | /** |
2630 | * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' | |
2631 | * @from: attach to all cgroups of a given task | |
2632 | * @tsk: the task to be attached | |
2633 | */ | |
2634 | int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) | |
2635 | { | |
3dd06ffa | 2636 | struct cgroup_root *root; |
7ae1bad9 TH |
2637 | int retval = 0; |
2638 | ||
47cfcd09 | 2639 | mutex_lock(&cgroup_mutex); |
985ed670 | 2640 | for_each_root(root) { |
96d365e0 TH |
2641 | struct cgroup *from_cgrp; |
2642 | ||
3dd06ffa | 2643 | if (root == &cgrp_dfl_root) |
985ed670 TH |
2644 | continue; |
2645 | ||
96d365e0 TH |
2646 | down_read(&css_set_rwsem); |
2647 | from_cgrp = task_cgroup_from_root(from, root); | |
2648 | up_read(&css_set_rwsem); | |
7ae1bad9 | 2649 | |
6f4b7e63 | 2650 | retval = cgroup_attach_task(from_cgrp, tsk, false); |
7ae1bad9 TH |
2651 | if (retval) |
2652 | break; | |
2653 | } | |
47cfcd09 | 2654 | mutex_unlock(&cgroup_mutex); |
7ae1bad9 TH |
2655 | |
2656 | return retval; | |
2657 | } | |
2658 | EXPORT_SYMBOL_GPL(cgroup_attach_task_all); | |
2659 | ||
acbef755 TH |
2660 | static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
2661 | char *buf, size_t nbytes, loff_t off) | |
74a1166d | 2662 | { |
acbef755 | 2663 | return __cgroup_procs_write(of, buf, nbytes, off, false); |
74a1166d BB |
2664 | } |
2665 | ||
acbef755 TH |
2666 | static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
2667 | char *buf, size_t nbytes, loff_t off) | |
af351026 | 2668 | { |
acbef755 | 2669 | return __cgroup_procs_write(of, buf, nbytes, off, true); |
af351026 PM |
2670 | } |
2671 | ||
451af504 TH |
2672 | static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
2673 | char *buf, size_t nbytes, loff_t off) | |
e788e066 | 2674 | { |
e76ecaee | 2675 | struct cgroup *cgrp; |
5f469907 | 2676 | |
e76ecaee | 2677 | BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
5f469907 | 2678 | |
e76ecaee TH |
2679 | cgrp = cgroup_kn_lock_live(of->kn); |
2680 | if (!cgrp) | |
e788e066 | 2681 | return -ENODEV; |
69e943b7 | 2682 | spin_lock(&release_agent_path_lock); |
e76ecaee TH |
2683 | strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
2684 | sizeof(cgrp->root->release_agent_path)); | |
69e943b7 | 2685 | spin_unlock(&release_agent_path_lock); |
e76ecaee | 2686 | cgroup_kn_unlock(of->kn); |
451af504 | 2687 | return nbytes; |
e788e066 PM |
2688 | } |
2689 | ||
2da8ca82 | 2690 | static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
e788e066 | 2691 | { |
2da8ca82 | 2692 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
182446d0 | 2693 | |
46cfeb04 | 2694 | spin_lock(&release_agent_path_lock); |
e788e066 | 2695 | seq_puts(seq, cgrp->root->release_agent_path); |
46cfeb04 | 2696 | spin_unlock(&release_agent_path_lock); |
e788e066 | 2697 | seq_putc(seq, '\n'); |
e788e066 PM |
2698 | return 0; |
2699 | } | |
2700 | ||
2da8ca82 | 2701 | static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
873fe09e | 2702 | { |
c1d5d42e | 2703 | seq_puts(seq, "0\n"); |
e788e066 PM |
2704 | return 0; |
2705 | } | |
2706 | ||
8ab456ac | 2707 | static void cgroup_print_ss_mask(struct seq_file *seq, unsigned long ss_mask) |
355e0c48 | 2708 | { |
f8f22e53 TH |
2709 | struct cgroup_subsys *ss; |
2710 | bool printed = false; | |
2711 | int ssid; | |
a742c59d | 2712 | |
a966a4ed AS |
2713 | for_each_subsys_which(ss, ssid, &ss_mask) { |
2714 | if (printed) | |
2715 | seq_putc(seq, ' '); | |
2716 | seq_printf(seq, "%s", ss->name); | |
2717 | printed = true; | |
e73d2c61 | 2718 | } |
f8f22e53 TH |
2719 | if (printed) |
2720 | seq_putc(seq, '\n'); | |
355e0c48 PM |
2721 | } |
2722 | ||
f8f22e53 TH |
2723 | /* show controllers which are currently attached to the default hierarchy */ |
2724 | static int cgroup_root_controllers_show(struct seq_file *seq, void *v) | |
db3b1497 | 2725 | { |
f8f22e53 TH |
2726 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2727 | ||
5533e011 TH |
2728 | cgroup_print_ss_mask(seq, cgrp->root->subsys_mask & |
2729 | ~cgrp_dfl_root_inhibit_ss_mask); | |
f8f22e53 | 2730 | return 0; |
db3b1497 PM |
2731 | } |
2732 | ||
f8f22e53 TH |
2733 | /* show controllers which are enabled from the parent */ |
2734 | static int cgroup_controllers_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2735 | { |
f8f22e53 TH |
2736 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2737 | ||
667c2491 | 2738 | cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control); |
f8f22e53 | 2739 | return 0; |
ddbcc7e8 PM |
2740 | } |
2741 | ||
f8f22e53 TH |
2742 | /* show controllers which are enabled for a given cgroup's children */ |
2743 | static int cgroup_subtree_control_show(struct seq_file *seq, void *v) | |
ddbcc7e8 | 2744 | { |
f8f22e53 TH |
2745 | struct cgroup *cgrp = seq_css(seq)->cgroup; |
2746 | ||
667c2491 | 2747 | cgroup_print_ss_mask(seq, cgrp->subtree_control); |
f8f22e53 TH |
2748 | return 0; |
2749 | } | |
2750 | ||
2751 | /** | |
2752 | * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy | |
2753 | * @cgrp: root of the subtree to update csses for | |
2754 | * | |
2755 | * @cgrp's child_subsys_mask has changed and its subtree's (self excluded) | |
2756 | * css associations need to be updated accordingly. This function looks up | |
2757 | * all css_sets which are attached to the subtree, creates the matching | |
2758 | * updated css_sets and migrates the tasks to the new ones. | |
2759 | */ | |
2760 | static int cgroup_update_dfl_csses(struct cgroup *cgrp) | |
2761 | { | |
2762 | LIST_HEAD(preloaded_csets); | |
2763 | struct cgroup_subsys_state *css; | |
2764 | struct css_set *src_cset; | |
2765 | int ret; | |
2766 | ||
f8f22e53 TH |
2767 | lockdep_assert_held(&cgroup_mutex); |
2768 | ||
3014dde7 TH |
2769 | percpu_down_write(&cgroup_threadgroup_rwsem); |
2770 | ||
f8f22e53 TH |
2771 | /* look up all csses currently attached to @cgrp's subtree */ |
2772 | down_read(&css_set_rwsem); | |
2773 | css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) { | |
2774 | struct cgrp_cset_link *link; | |
2775 | ||
2776 | /* self is not affected by child_subsys_mask change */ | |
2777 | if (css->cgroup == cgrp) | |
2778 | continue; | |
2779 | ||
2780 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) | |
2781 | cgroup_migrate_add_src(link->cset, cgrp, | |
2782 | &preloaded_csets); | |
2783 | } | |
2784 | up_read(&css_set_rwsem); | |
2785 | ||
2786 | /* NULL dst indicates self on default hierarchy */ | |
2787 | ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets); | |
2788 | if (ret) | |
2789 | goto out_finish; | |
2790 | ||
2791 | list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { | |
2792 | struct task_struct *last_task = NULL, *task; | |
2793 | ||
2794 | /* src_csets precede dst_csets, break on the first dst_cset */ | |
2795 | if (!src_cset->mg_src_cgrp) | |
2796 | break; | |
2797 | ||
2798 | /* | |
2799 | * All tasks in src_cset need to be migrated to the | |
2800 | * matching dst_cset. Empty it process by process. We | |
2801 | * walk tasks but migrate processes. The leader might even | |
2802 | * belong to a different cset but such src_cset would also | |
2803 | * be among the target src_csets because the default | |
2804 | * hierarchy enforces per-process membership. | |
2805 | */ | |
2806 | while (true) { | |
2807 | down_read(&css_set_rwsem); | |
2808 | task = list_first_entry_or_null(&src_cset->tasks, | |
2809 | struct task_struct, cg_list); | |
2810 | if (task) { | |
2811 | task = task->group_leader; | |
2812 | WARN_ON_ONCE(!task_css_set(task)->mg_src_cgrp); | |
2813 | get_task_struct(task); | |
2814 | } | |
2815 | up_read(&css_set_rwsem); | |
2816 | ||
2817 | if (!task) | |
2818 | break; | |
2819 | ||
2820 | /* guard against possible infinite loop */ | |
2821 | if (WARN(last_task == task, | |
2822 | "cgroup: update_dfl_csses failed to make progress, aborting in inconsistent state\n")) | |
2823 | goto out_finish; | |
2824 | last_task = task; | |
2825 | ||
f8f22e53 TH |
2826 | ret = cgroup_migrate(src_cset->dfl_cgrp, task, true); |
2827 | ||
f8f22e53 TH |
2828 | put_task_struct(task); |
2829 | ||
2830 | if (WARN(ret, "cgroup: failed to update controllers for the default hierarchy (%d), further operations may crash or hang\n", ret)) | |
2831 | goto out_finish; | |
2832 | } | |
2833 | } | |
2834 | ||
2835 | out_finish: | |
2836 | cgroup_migrate_finish(&preloaded_csets); | |
3014dde7 | 2837 | percpu_up_write(&cgroup_threadgroup_rwsem); |
f8f22e53 TH |
2838 | return ret; |
2839 | } | |
2840 | ||
2841 | /* change the enabled child controllers for a cgroup in the default hierarchy */ | |
451af504 TH |
2842 | static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
2843 | char *buf, size_t nbytes, | |
2844 | loff_t off) | |
f8f22e53 | 2845 | { |
8ab456ac AS |
2846 | unsigned long enable = 0, disable = 0; |
2847 | unsigned long css_enable, css_disable, old_sc, new_sc, old_ss, new_ss; | |
a9746d8d | 2848 | struct cgroup *cgrp, *child; |
f8f22e53 | 2849 | struct cgroup_subsys *ss; |
451af504 | 2850 | char *tok; |
f8f22e53 TH |
2851 | int ssid, ret; |
2852 | ||
2853 | /* | |
d37167ab TH |
2854 | * Parse input - space separated list of subsystem names prefixed |
2855 | * with either + or -. | |
f8f22e53 | 2856 | */ |
451af504 TH |
2857 | buf = strstrip(buf); |
2858 | while ((tok = strsep(&buf, " "))) { | |
a966a4ed AS |
2859 | unsigned long tmp_ss_mask = ~cgrp_dfl_root_inhibit_ss_mask; |
2860 | ||
d37167ab TH |
2861 | if (tok[0] == '\0') |
2862 | continue; | |
a966a4ed | 2863 | for_each_subsys_which(ss, ssid, &tmp_ss_mask) { |
fc5ed1e9 TH |
2864 | if (!cgroup_ssid_enabled(ssid) || |
2865 | strcmp(tok + 1, ss->name)) | |
f8f22e53 TH |
2866 | continue; |
2867 | ||
2868 | if (*tok == '+') { | |
7d331fa9 TH |
2869 | enable |= 1 << ssid; |
2870 | disable &= ~(1 << ssid); | |
f8f22e53 | 2871 | } else if (*tok == '-') { |
7d331fa9 TH |
2872 | disable |= 1 << ssid; |
2873 | enable &= ~(1 << ssid); | |
f8f22e53 TH |
2874 | } else { |
2875 | return -EINVAL; | |
2876 | } | |
2877 | break; | |
2878 | } | |
2879 | if (ssid == CGROUP_SUBSYS_COUNT) | |
2880 | return -EINVAL; | |
2881 | } | |
2882 | ||
a9746d8d TH |
2883 | cgrp = cgroup_kn_lock_live(of->kn); |
2884 | if (!cgrp) | |
2885 | return -ENODEV; | |
f8f22e53 TH |
2886 | |
2887 | for_each_subsys(ss, ssid) { | |
2888 | if (enable & (1 << ssid)) { | |
667c2491 | 2889 | if (cgrp->subtree_control & (1 << ssid)) { |
f8f22e53 TH |
2890 | enable &= ~(1 << ssid); |
2891 | continue; | |
2892 | } | |
2893 | ||
c29adf24 TH |
2894 | /* unavailable or not enabled on the parent? */ |
2895 | if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) || | |
2896 | (cgroup_parent(cgrp) && | |
667c2491 | 2897 | !(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) { |
c29adf24 TH |
2898 | ret = -ENOENT; |
2899 | goto out_unlock; | |
2900 | } | |
f8f22e53 | 2901 | } else if (disable & (1 << ssid)) { |
667c2491 | 2902 | if (!(cgrp->subtree_control & (1 << ssid))) { |
f8f22e53 TH |
2903 | disable &= ~(1 << ssid); |
2904 | continue; | |
2905 | } | |
2906 | ||
2907 | /* a child has it enabled? */ | |
2908 | cgroup_for_each_live_child(child, cgrp) { | |
667c2491 | 2909 | if (child->subtree_control & (1 << ssid)) { |
f8f22e53 | 2910 | ret = -EBUSY; |
ddab2b6e | 2911 | goto out_unlock; |
f8f22e53 TH |
2912 | } |
2913 | } | |
2914 | } | |
2915 | } | |
2916 | ||
2917 | if (!enable && !disable) { | |
2918 | ret = 0; | |
ddab2b6e | 2919 | goto out_unlock; |
f8f22e53 TH |
2920 | } |
2921 | ||
2922 | /* | |
667c2491 | 2923 | * Except for the root, subtree_control must be zero for a cgroup |
f8f22e53 TH |
2924 | * with tasks so that child cgroups don't compete against tasks. |
2925 | */ | |
d51f39b0 | 2926 | if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) { |
f8f22e53 TH |
2927 | ret = -EBUSY; |
2928 | goto out_unlock; | |
2929 | } | |
2930 | ||
2931 | /* | |
f63070d3 TH |
2932 | * Update subsys masks and calculate what needs to be done. More |
2933 | * subsystems than specified may need to be enabled or disabled | |
2934 | * depending on subsystem dependencies. | |
2935 | */ | |
755bf5ee TH |
2936 | old_sc = cgrp->subtree_control; |
2937 | old_ss = cgrp->child_subsys_mask; | |
2938 | new_sc = (old_sc | enable) & ~disable; | |
2939 | new_ss = cgroup_calc_child_subsys_mask(cgrp, new_sc); | |
f63070d3 | 2940 | |
755bf5ee TH |
2941 | css_enable = ~old_ss & new_ss; |
2942 | css_disable = old_ss & ~new_ss; | |
f63070d3 TH |
2943 | enable |= css_enable; |
2944 | disable |= css_disable; | |
c29adf24 | 2945 | |
db6e3053 TH |
2946 | /* |
2947 | * Because css offlining is asynchronous, userland might try to | |
2948 | * re-enable the same controller while the previous instance is | |
2949 | * still around. In such cases, wait till it's gone using | |
2950 | * offline_waitq. | |
2951 | */ | |
a966a4ed | 2952 | for_each_subsys_which(ss, ssid, &css_enable) { |
db6e3053 TH |
2953 | cgroup_for_each_live_child(child, cgrp) { |
2954 | DEFINE_WAIT(wait); | |
2955 | ||
2956 | if (!cgroup_css(child, ss)) | |
2957 | continue; | |
2958 | ||
2959 | cgroup_get(child); | |
2960 | prepare_to_wait(&child->offline_waitq, &wait, | |
2961 | TASK_UNINTERRUPTIBLE); | |
2962 | cgroup_kn_unlock(of->kn); | |
2963 | schedule(); | |
2964 | finish_wait(&child->offline_waitq, &wait); | |
2965 | cgroup_put(child); | |
2966 | ||
2967 | return restart_syscall(); | |
2968 | } | |
2969 | } | |
2970 | ||
755bf5ee TH |
2971 | cgrp->subtree_control = new_sc; |
2972 | cgrp->child_subsys_mask = new_ss; | |
2973 | ||
f63070d3 TH |
2974 | /* |
2975 | * Create new csses or make the existing ones visible. A css is | |
2976 | * created invisible if it's being implicitly enabled through | |
2977 | * dependency. An invisible css is made visible when the userland | |
2978 | * explicitly enables it. | |
f8f22e53 TH |
2979 | */ |
2980 | for_each_subsys(ss, ssid) { | |
2981 | if (!(enable & (1 << ssid))) | |
2982 | continue; | |
2983 | ||
2984 | cgroup_for_each_live_child(child, cgrp) { | |
f63070d3 TH |
2985 | if (css_enable & (1 << ssid)) |
2986 | ret = create_css(child, ss, | |
2987 | cgrp->subtree_control & (1 << ssid)); | |
2988 | else | |
2989 | ret = cgroup_populate_dir(child, 1 << ssid); | |
f8f22e53 TH |
2990 | if (ret) |
2991 | goto err_undo_css; | |
2992 | } | |
2993 | } | |
2994 | ||
c29adf24 TH |
2995 | /* |
2996 | * At this point, cgroup_e_css() results reflect the new csses | |
2997 | * making the following cgroup_update_dfl_csses() properly update | |
2998 | * css associations of all tasks in the subtree. | |
2999 | */ | |
f8f22e53 TH |
3000 | ret = cgroup_update_dfl_csses(cgrp); |
3001 | if (ret) | |
3002 | goto err_undo_css; | |
3003 | ||
f63070d3 TH |
3004 | /* |
3005 | * All tasks are migrated out of disabled csses. Kill or hide | |
3006 | * them. A css is hidden when the userland requests it to be | |
b4536f0c TH |
3007 | * disabled while other subsystems are still depending on it. The |
3008 | * css must not actively control resources and be in the vanilla | |
3009 | * state if it's made visible again later. Controllers which may | |
3010 | * be depended upon should provide ->css_reset() for this purpose. | |
f63070d3 | 3011 | */ |
f8f22e53 TH |
3012 | for_each_subsys(ss, ssid) { |
3013 | if (!(disable & (1 << ssid))) | |
3014 | continue; | |
3015 | ||
f63070d3 | 3016 | cgroup_for_each_live_child(child, cgrp) { |
b4536f0c TH |
3017 | struct cgroup_subsys_state *css = cgroup_css(child, ss); |
3018 | ||
3019 | if (css_disable & (1 << ssid)) { | |
3020 | kill_css(css); | |
3021 | } else { | |
f63070d3 | 3022 | cgroup_clear_dir(child, 1 << ssid); |
b4536f0c TH |
3023 | if (ss->css_reset) |
3024 | ss->css_reset(css); | |
3025 | } | |
f63070d3 | 3026 | } |
f8f22e53 TH |
3027 | } |
3028 | ||
56c807ba TH |
3029 | /* |
3030 | * The effective csses of all the descendants (excluding @cgrp) may | |
3031 | * have changed. Subsystems can optionally subscribe to this event | |
3032 | * by implementing ->css_e_css_changed() which is invoked if any of | |
3033 | * the effective csses seen from the css's cgroup may have changed. | |
3034 | */ | |
3035 | for_each_subsys(ss, ssid) { | |
3036 | struct cgroup_subsys_state *this_css = cgroup_css(cgrp, ss); | |
3037 | struct cgroup_subsys_state *css; | |
3038 | ||
3039 | if (!ss->css_e_css_changed || !this_css) | |
3040 | continue; | |
3041 | ||
3042 | css_for_each_descendant_pre(css, this_css) | |
3043 | if (css != this_css) | |
3044 | ss->css_e_css_changed(css); | |
3045 | } | |
3046 | ||
f8f22e53 TH |
3047 | kernfs_activate(cgrp->kn); |
3048 | ret = 0; | |
3049 | out_unlock: | |
a9746d8d | 3050 | cgroup_kn_unlock(of->kn); |
451af504 | 3051 | return ret ?: nbytes; |
f8f22e53 TH |
3052 | |
3053 | err_undo_css: | |
755bf5ee TH |
3054 | cgrp->subtree_control = old_sc; |
3055 | cgrp->child_subsys_mask = old_ss; | |
f8f22e53 TH |
3056 | |
3057 | for_each_subsys(ss, ssid) { | |
3058 | if (!(enable & (1 << ssid))) | |
3059 | continue; | |
3060 | ||
3061 | cgroup_for_each_live_child(child, cgrp) { | |
3062 | struct cgroup_subsys_state *css = cgroup_css(child, ss); | |
f63070d3 TH |
3063 | |
3064 | if (!css) | |
3065 | continue; | |
3066 | ||
3067 | if (css_enable & (1 << ssid)) | |
f8f22e53 | 3068 | kill_css(css); |
f63070d3 TH |
3069 | else |
3070 | cgroup_clear_dir(child, 1 << ssid); | |
f8f22e53 TH |
3071 | } |
3072 | } | |
3073 | goto out_unlock; | |
3074 | } | |
3075 | ||
4a07c222 | 3076 | static int cgroup_events_show(struct seq_file *seq, void *v) |
842b597e | 3077 | { |
4a07c222 TH |
3078 | seq_printf(seq, "populated %d\n", |
3079 | (bool)seq_css(seq)->cgroup->populated_cnt); | |
842b597e TH |
3080 | return 0; |
3081 | } | |
3082 | ||
2bd59d48 TH |
3083 | static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
3084 | size_t nbytes, loff_t off) | |
355e0c48 | 3085 | { |
2bd59d48 TH |
3086 | struct cgroup *cgrp = of->kn->parent->priv; |
3087 | struct cftype *cft = of->kn->priv; | |
3088 | struct cgroup_subsys_state *css; | |
a742c59d | 3089 | int ret; |
355e0c48 | 3090 | |
b4168640 TH |
3091 | if (cft->write) |
3092 | return cft->write(of, buf, nbytes, off); | |
3093 | ||
2bd59d48 TH |
3094 | /* |
3095 | * kernfs guarantees that a file isn't deleted with operations in | |
3096 | * flight, which means that the matching css is and stays alive and | |
3097 | * doesn't need to be pinned. The RCU locking is not necessary | |
3098 | * either. It's just for the convenience of using cgroup_css(). | |
3099 | */ | |
3100 | rcu_read_lock(); | |
3101 | css = cgroup_css(cgrp, cft->ss); | |
3102 | rcu_read_unlock(); | |
a742c59d | 3103 | |
451af504 | 3104 | if (cft->write_u64) { |
a742c59d TH |
3105 | unsigned long long v; |
3106 | ret = kstrtoull(buf, 0, &v); | |
3107 | if (!ret) | |
3108 | ret = cft->write_u64(css, cft, v); | |
3109 | } else if (cft->write_s64) { | |
3110 | long long v; | |
3111 | ret = kstrtoll(buf, 0, &v); | |
3112 | if (!ret) | |
3113 | ret = cft->write_s64(css, cft, v); | |
e73d2c61 | 3114 | } else { |
a742c59d | 3115 | ret = -EINVAL; |
e73d2c61 | 3116 | } |
2bd59d48 | 3117 | |
a742c59d | 3118 | return ret ?: nbytes; |
355e0c48 PM |
3119 | } |
3120 | ||
6612f05b | 3121 | static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
db3b1497 | 3122 | { |
2bd59d48 | 3123 | return seq_cft(seq)->seq_start(seq, ppos); |
db3b1497 PM |
3124 | } |
3125 | ||
6612f05b | 3126 | static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
ddbcc7e8 | 3127 | { |
2bd59d48 | 3128 | return seq_cft(seq)->seq_next(seq, v, ppos); |
ddbcc7e8 PM |
3129 | } |
3130 | ||
6612f05b | 3131 | static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
ddbcc7e8 | 3132 | { |
2bd59d48 | 3133 | seq_cft(seq)->seq_stop(seq, v); |
ddbcc7e8 PM |
3134 | } |
3135 | ||
91796569 | 3136 | static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
e73d2c61 | 3137 | { |
7da11279 TH |
3138 | struct cftype *cft = seq_cft(m); |
3139 | struct cgroup_subsys_state *css = seq_css(m); | |
e73d2c61 | 3140 | |
2da8ca82 TH |
3141 | if (cft->seq_show) |
3142 | return cft->seq_show(m, arg); | |
e73d2c61 | 3143 | |
f4c753b7 | 3144 | if (cft->read_u64) |
896f5199 TH |
3145 | seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
3146 | else if (cft->read_s64) | |
3147 | seq_printf(m, "%lld\n", cft->read_s64(css, cft)); | |
3148 | else | |
3149 | return -EINVAL; | |
3150 | return 0; | |
91796569 PM |
3151 | } |
3152 | ||
2bd59d48 TH |
3153 | static struct kernfs_ops cgroup_kf_single_ops = { |
3154 | .atomic_write_len = PAGE_SIZE, | |
3155 | .write = cgroup_file_write, | |
3156 | .seq_show = cgroup_seqfile_show, | |
91796569 PM |
3157 | }; |
3158 | ||
2bd59d48 TH |
3159 | static struct kernfs_ops cgroup_kf_ops = { |
3160 | .atomic_write_len = PAGE_SIZE, | |
3161 | .write = cgroup_file_write, | |
3162 | .seq_start = cgroup_seqfile_start, | |
3163 | .seq_next = cgroup_seqfile_next, | |
3164 | .seq_stop = cgroup_seqfile_stop, | |
3165 | .seq_show = cgroup_seqfile_show, | |
3166 | }; | |
ddbcc7e8 PM |
3167 | |
3168 | /* | |
3169 | * cgroup_rename - Only allow simple rename of directories in place. | |
3170 | */ | |
2bd59d48 TH |
3171 | static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
3172 | const char *new_name_str) | |
ddbcc7e8 | 3173 | { |
2bd59d48 | 3174 | struct cgroup *cgrp = kn->priv; |
65dff759 | 3175 | int ret; |
65dff759 | 3176 | |
2bd59d48 | 3177 | if (kernfs_type(kn) != KERNFS_DIR) |
ddbcc7e8 | 3178 | return -ENOTDIR; |
2bd59d48 | 3179 | if (kn->parent != new_parent) |
ddbcc7e8 | 3180 | return -EIO; |
65dff759 | 3181 | |
6db8e85c TH |
3182 | /* |
3183 | * This isn't a proper migration and its usefulness is very | |
aa6ec29b | 3184 | * limited. Disallow on the default hierarchy. |
6db8e85c | 3185 | */ |
aa6ec29b | 3186 | if (cgroup_on_dfl(cgrp)) |
6db8e85c | 3187 | return -EPERM; |
099fca32 | 3188 | |
e1b2dc17 | 3189 | /* |
8353da1f | 3190 | * We're gonna grab cgroup_mutex which nests outside kernfs |
e1b2dc17 | 3191 | * active_ref. kernfs_rename() doesn't require active_ref |
8353da1f | 3192 | * protection. Break them before grabbing cgroup_mutex. |
e1b2dc17 TH |
3193 | */ |
3194 | kernfs_break_active_protection(new_parent); | |
3195 | kernfs_break_active_protection(kn); | |
099fca32 | 3196 | |
2bd59d48 | 3197 | mutex_lock(&cgroup_mutex); |
099fca32 | 3198 | |
2bd59d48 | 3199 | ret = kernfs_rename(kn, new_parent, new_name_str); |
099fca32 | 3200 | |
2bd59d48 | 3201 | mutex_unlock(&cgroup_mutex); |
e1b2dc17 TH |
3202 | |
3203 | kernfs_unbreak_active_protection(kn); | |
3204 | kernfs_unbreak_active_protection(new_parent); | |
2bd59d48 | 3205 | return ret; |
099fca32 LZ |
3206 | } |
3207 | ||
49957f8e TH |
3208 | /* set uid and gid of cgroup dirs and files to that of the creator */ |
3209 | static int cgroup_kn_set_ugid(struct kernfs_node *kn) | |
3210 | { | |
3211 | struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, | |
3212 | .ia_uid = current_fsuid(), | |
3213 | .ia_gid = current_fsgid(), }; | |
3214 | ||
3215 | if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && | |
3216 | gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) | |
3217 | return 0; | |
3218 | ||
3219 | return kernfs_setattr(kn, &iattr); | |
3220 | } | |
3221 | ||
2bb566cb | 3222 | static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) |
ddbcc7e8 | 3223 | { |
8d7e6fb0 | 3224 | char name[CGROUP_FILE_NAME_MAX]; |
2bd59d48 TH |
3225 | struct kernfs_node *kn; |
3226 | struct lock_class_key *key = NULL; | |
49957f8e | 3227 | int ret; |
05ef1d7c | 3228 | |
2bd59d48 TH |
3229 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
3230 | key = &cft->lockdep_key; | |
3231 | #endif | |
3232 | kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), | |
3233 | cgroup_file_mode(cft), 0, cft->kf_ops, cft, | |
dfeb0750 | 3234 | NULL, key); |
49957f8e TH |
3235 | if (IS_ERR(kn)) |
3236 | return PTR_ERR(kn); | |
3237 | ||
3238 | ret = cgroup_kn_set_ugid(kn); | |
f8f22e53 | 3239 | if (ret) { |
49957f8e | 3240 | kernfs_remove(kn); |
f8f22e53 TH |
3241 | return ret; |
3242 | } | |
3243 | ||
187fe840 TH |
3244 | if (cft->write == cgroup_procs_write) |
3245 | cgrp->procs_kn = kn; | |
4a07c222 TH |
3246 | else if (cft->seq_show == cgroup_events_show) |
3247 | cgrp->events_kn = kn; | |
f8f22e53 | 3248 | return 0; |
ddbcc7e8 PM |
3249 | } |
3250 | ||
b1f28d31 TH |
3251 | /** |
3252 | * cgroup_addrm_files - add or remove files to a cgroup directory | |
3253 | * @cgrp: the target cgroup | |
b1f28d31 TH |
3254 | * @cfts: array of cftypes to be added |
3255 | * @is_add: whether to add or remove | |
3256 | * | |
3257 | * Depending on @is_add, add or remove files defined by @cfts on @cgrp. | |
2bb566cb TH |
3258 | * For removals, this function never fails. If addition fails, this |
3259 | * function doesn't remove files already added. The caller is responsible | |
3260 | * for cleaning up. | |
b1f28d31 | 3261 | */ |
2bb566cb TH |
3262 | static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], |
3263 | bool is_add) | |
ddbcc7e8 | 3264 | { |
03b1cde6 | 3265 | struct cftype *cft; |
b1f28d31 TH |
3266 | int ret; |
3267 | ||
01f6474c | 3268 | lockdep_assert_held(&cgroup_mutex); |
db0416b6 TH |
3269 | |
3270 | for (cft = cfts; cft->name[0] != '\0'; cft++) { | |
f33fddc2 | 3271 | /* does cft->flags tell us to skip this file on @cgrp? */ |
05ebb6e6 | 3272 | if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
8cbbf2c9 | 3273 | continue; |
05ebb6e6 | 3274 | if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
873fe09e | 3275 | continue; |
d51f39b0 | 3276 | if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
f33fddc2 | 3277 | continue; |
d51f39b0 | 3278 | if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
f33fddc2 G |
3279 | continue; |
3280 | ||
2739d3cc | 3281 | if (is_add) { |
2bb566cb | 3282 | ret = cgroup_add_file(cgrp, cft); |
b1f28d31 | 3283 | if (ret) { |
ed3d261b JP |
3284 | pr_warn("%s: failed to add %s, err=%d\n", |
3285 | __func__, cft->name, ret); | |
b1f28d31 TH |
3286 | return ret; |
3287 | } | |
2739d3cc LZ |
3288 | } else { |
3289 | cgroup_rm_file(cgrp, cft); | |
db0416b6 | 3290 | } |
ddbcc7e8 | 3291 | } |
b1f28d31 | 3292 | return 0; |
ddbcc7e8 PM |
3293 | } |
3294 | ||
21a2d343 | 3295 | static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
8e3f6541 TH |
3296 | { |
3297 | LIST_HEAD(pending); | |
2bb566cb | 3298 | struct cgroup_subsys *ss = cfts[0].ss; |
3dd06ffa | 3299 | struct cgroup *root = &ss->root->cgrp; |
492eb21b | 3300 | struct cgroup_subsys_state *css; |
9ccece80 | 3301 | int ret = 0; |
8e3f6541 | 3302 | |
01f6474c | 3303 | lockdep_assert_held(&cgroup_mutex); |
e8c82d20 | 3304 | |
e8c82d20 | 3305 | /* add/rm files for all cgroups created before */ |
ca8bdcaf | 3306 | css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
492eb21b TH |
3307 | struct cgroup *cgrp = css->cgroup; |
3308 | ||
e8c82d20 LZ |
3309 | if (cgroup_is_dead(cgrp)) |
3310 | continue; | |
3311 | ||
21a2d343 | 3312 | ret = cgroup_addrm_files(cgrp, cfts, is_add); |
9ccece80 TH |
3313 | if (ret) |
3314 | break; | |
8e3f6541 | 3315 | } |
21a2d343 TH |
3316 | |
3317 | if (is_add && !ret) | |
3318 | kernfs_activate(root->kn); | |
9ccece80 | 3319 | return ret; |
8e3f6541 TH |
3320 | } |
3321 | ||
2da440a2 | 3322 | static void cgroup_exit_cftypes(struct cftype *cfts) |
8e3f6541 | 3323 | { |
2bb566cb | 3324 | struct cftype *cft; |
8e3f6541 | 3325 | |
2bd59d48 TH |
3326 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3327 | /* free copy for custom atomic_write_len, see init_cftypes() */ | |
3328 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) | |
3329 | kfree(cft->kf_ops); | |
3330 | cft->kf_ops = NULL; | |
2da440a2 | 3331 | cft->ss = NULL; |
a8ddc821 TH |
3332 | |
3333 | /* revert flags set by cgroup core while adding @cfts */ | |
05ebb6e6 | 3334 | cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
2bd59d48 | 3335 | } |
2da440a2 TH |
3336 | } |
3337 | ||
2bd59d48 | 3338 | static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
2da440a2 TH |
3339 | { |
3340 | struct cftype *cft; | |
3341 | ||
2bd59d48 TH |
3342 | for (cft = cfts; cft->name[0] != '\0'; cft++) { |
3343 | struct kernfs_ops *kf_ops; | |
3344 | ||
0adb0704 TH |
3345 | WARN_ON(cft->ss || cft->kf_ops); |
3346 | ||
2bd59d48 TH |
3347 | if (cft->seq_start) |
3348 | kf_ops = &cgroup_kf_ops; | |
3349 | else | |
3350 | kf_ops = &cgroup_kf_single_ops; | |
3351 | ||
3352 | /* | |
3353 | * Ugh... if @cft wants a custom max_write_len, we need to | |
3354 | * make a copy of kf_ops to set its atomic_write_len. | |
3355 | */ | |
3356 | if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { | |
3357 | kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); | |
3358 | if (!kf_ops) { | |
3359 | cgroup_exit_cftypes(cfts); | |
3360 | return -ENOMEM; | |
3361 | } | |
3362 | kf_ops->atomic_write_len = cft->max_write_len; | |
3363 | } | |
8e3f6541 | 3364 | |
2bd59d48 | 3365 | cft->kf_ops = kf_ops; |
2bb566cb | 3366 | cft->ss = ss; |
2bd59d48 | 3367 | } |
2bb566cb | 3368 | |
2bd59d48 | 3369 | return 0; |
2da440a2 TH |
3370 | } |
3371 | ||
21a2d343 TH |
3372 | static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
3373 | { | |
01f6474c | 3374 | lockdep_assert_held(&cgroup_mutex); |
21a2d343 TH |
3375 | |
3376 | if (!cfts || !cfts[0].ss) | |
3377 | return -ENOENT; | |
3378 | ||
3379 | list_del(&cfts->node); | |
3380 | cgroup_apply_cftypes(cfts, false); | |
3381 | cgroup_exit_cftypes(cfts); | |
3382 | return 0; | |
8e3f6541 | 3383 | } |
8e3f6541 | 3384 | |
79578621 TH |
3385 | /** |
3386 | * cgroup_rm_cftypes - remove an array of cftypes from a subsystem | |
79578621 TH |
3387 | * @cfts: zero-length name terminated array of cftypes |
3388 | * | |
2bb566cb TH |
3389 | * Unregister @cfts. Files described by @cfts are removed from all |
3390 | * existing cgroups and all future cgroups won't have them either. This | |
3391 | * function can be called anytime whether @cfts' subsys is attached or not. | |
79578621 TH |
3392 | * |
3393 | * Returns 0 on successful unregistration, -ENOENT if @cfts is not | |
2bb566cb | 3394 | * registered. |
79578621 | 3395 | */ |
2bb566cb | 3396 | int cgroup_rm_cftypes(struct cftype *cfts) |
79578621 | 3397 | { |
21a2d343 | 3398 | int ret; |
79578621 | 3399 | |
01f6474c | 3400 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3401 | ret = cgroup_rm_cftypes_locked(cfts); |
01f6474c | 3402 | mutex_unlock(&cgroup_mutex); |
21a2d343 | 3403 | return ret; |
80b13586 TH |
3404 | } |
3405 | ||
8e3f6541 TH |
3406 | /** |
3407 | * cgroup_add_cftypes - add an array of cftypes to a subsystem | |
3408 | * @ss: target cgroup subsystem | |
3409 | * @cfts: zero-length name terminated array of cftypes | |
3410 | * | |
3411 | * Register @cfts to @ss. Files described by @cfts are created for all | |
3412 | * existing cgroups to which @ss is attached and all future cgroups will | |
3413 | * have them too. This function can be called anytime whether @ss is | |
3414 | * attached or not. | |
3415 | * | |
3416 | * Returns 0 on successful registration, -errno on failure. Note that this | |
3417 | * function currently returns 0 as long as @cfts registration is successful | |
3418 | * even if some file creation attempts on existing cgroups fail. | |
3419 | */ | |
2cf669a5 | 3420 | static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
8e3f6541 | 3421 | { |
9ccece80 | 3422 | int ret; |
8e3f6541 | 3423 | |
fc5ed1e9 | 3424 | if (!cgroup_ssid_enabled(ss->id)) |
c731ae1d LZ |
3425 | return 0; |
3426 | ||
dc5736ed LZ |
3427 | if (!cfts || cfts[0].name[0] == '\0') |
3428 | return 0; | |
2bb566cb | 3429 | |
2bd59d48 TH |
3430 | ret = cgroup_init_cftypes(ss, cfts); |
3431 | if (ret) | |
3432 | return ret; | |
79578621 | 3433 | |
01f6474c | 3434 | mutex_lock(&cgroup_mutex); |
21a2d343 | 3435 | |
0adb0704 | 3436 | list_add_tail(&cfts->node, &ss->cfts); |
21a2d343 | 3437 | ret = cgroup_apply_cftypes(cfts, true); |
9ccece80 | 3438 | if (ret) |
21a2d343 | 3439 | cgroup_rm_cftypes_locked(cfts); |
79578621 | 3440 | |
01f6474c | 3441 | mutex_unlock(&cgroup_mutex); |
9ccece80 | 3442 | return ret; |
79578621 TH |
3443 | } |
3444 | ||
a8ddc821 TH |
3445 | /** |
3446 | * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy | |
3447 | * @ss: target cgroup subsystem | |
3448 | * @cfts: zero-length name terminated array of cftypes | |
3449 | * | |
3450 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3451 | * the default hierarchy. | |
3452 | */ | |
3453 | int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) | |
3454 | { | |
3455 | struct cftype *cft; | |
3456 | ||
3457 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
05ebb6e6 | 3458 | cft->flags |= __CFTYPE_ONLY_ON_DFL; |
a8ddc821 TH |
3459 | return cgroup_add_cftypes(ss, cfts); |
3460 | } | |
3461 | ||
3462 | /** | |
3463 | * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies | |
3464 | * @ss: target cgroup subsystem | |
3465 | * @cfts: zero-length name terminated array of cftypes | |
3466 | * | |
3467 | * Similar to cgroup_add_cftypes() but the added files are only used for | |
3468 | * the legacy hierarchies. | |
3469 | */ | |
2cf669a5 TH |
3470 | int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
3471 | { | |
a8ddc821 TH |
3472 | struct cftype *cft; |
3473 | ||
fa8137be VG |
3474 | /* |
3475 | * If legacy_flies_on_dfl, we want to show the legacy files on the | |
3476 | * dfl hierarchy but iff the target subsystem hasn't been updated | |
3477 | * for the dfl hierarchy yet. | |
3478 | */ | |
3479 | if (!cgroup_legacy_files_on_dfl || | |
3480 | ss->dfl_cftypes != ss->legacy_cftypes) { | |
3481 | for (cft = cfts; cft && cft->name[0] != '\0'; cft++) | |
3482 | cft->flags |= __CFTYPE_NOT_ON_DFL; | |
3483 | } | |
3484 | ||
2cf669a5 TH |
3485 | return cgroup_add_cftypes(ss, cfts); |
3486 | } | |
3487 | ||
a043e3b2 LZ |
3488 | /** |
3489 | * cgroup_task_count - count the number of tasks in a cgroup. | |
3490 | * @cgrp: the cgroup in question | |
3491 | * | |
3492 | * Return the number of tasks in the cgroup. | |
3493 | */ | |
07bc356e | 3494 | static int cgroup_task_count(const struct cgroup *cgrp) |
bbcb81d0 PM |
3495 | { |
3496 | int count = 0; | |
69d0206c | 3497 | struct cgrp_cset_link *link; |
817929ec | 3498 | |
96d365e0 | 3499 | down_read(&css_set_rwsem); |
69d0206c TH |
3500 | list_for_each_entry(link, &cgrp->cset_links, cset_link) |
3501 | count += atomic_read(&link->cset->refcount); | |
96d365e0 | 3502 | up_read(&css_set_rwsem); |
bbcb81d0 PM |
3503 | return count; |
3504 | } | |
3505 | ||
53fa5261 | 3506 | /** |
492eb21b | 3507 | * css_next_child - find the next child of a given css |
c2931b70 TH |
3508 | * @pos: the current position (%NULL to initiate traversal) |
3509 | * @parent: css whose children to walk | |
53fa5261 | 3510 | * |
c2931b70 | 3511 | * This function returns the next child of @parent and should be called |
87fb54f1 | 3512 | * under either cgroup_mutex or RCU read lock. The only requirement is |
c2931b70 TH |
3513 | * that @parent and @pos are accessible. The next sibling is guaranteed to |
3514 | * be returned regardless of their states. | |
3515 | * | |
3516 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3517 | * css which finished ->css_online() is guaranteed to be visible in the | |
3518 | * future iterations and will stay visible until the last reference is put. | |
3519 | * A css which hasn't finished ->css_online() or already finished | |
3520 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3521 | * responsibility to synchronize against on/offlining. | |
53fa5261 | 3522 | */ |
c2931b70 TH |
3523 | struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
3524 | struct cgroup_subsys_state *parent) | |
53fa5261 | 3525 | { |
c2931b70 | 3526 | struct cgroup_subsys_state *next; |
53fa5261 | 3527 | |
8353da1f | 3528 | cgroup_assert_mutex_or_rcu_locked(); |
53fa5261 TH |
3529 | |
3530 | /* | |
de3f0341 TH |
3531 | * @pos could already have been unlinked from the sibling list. |
3532 | * Once a cgroup is removed, its ->sibling.next is no longer | |
3533 | * updated when its next sibling changes. CSS_RELEASED is set when | |
3534 | * @pos is taken off list, at which time its next pointer is valid, | |
3535 | * and, as releases are serialized, the one pointed to by the next | |
3536 | * pointer is guaranteed to not have started release yet. This | |
3537 | * implies that if we observe !CSS_RELEASED on @pos in this RCU | |
3538 | * critical section, the one pointed to by its next pointer is | |
3539 | * guaranteed to not have finished its RCU grace period even if we | |
3540 | * have dropped rcu_read_lock() inbetween iterations. | |
3b287a50 | 3541 | * |
de3f0341 TH |
3542 | * If @pos has CSS_RELEASED set, its next pointer can't be |
3543 | * dereferenced; however, as each css is given a monotonically | |
3544 | * increasing unique serial number and always appended to the | |
3545 | * sibling list, the next one can be found by walking the parent's | |
3546 | * children until the first css with higher serial number than | |
3547 | * @pos's. While this path can be slower, it happens iff iteration | |
3548 | * races against release and the race window is very small. | |
53fa5261 | 3549 | */ |
3b287a50 | 3550 | if (!pos) { |
c2931b70 TH |
3551 | next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
3552 | } else if (likely(!(pos->flags & CSS_RELEASED))) { | |
3553 | next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); | |
3b287a50 | 3554 | } else { |
c2931b70 | 3555 | list_for_each_entry_rcu(next, &parent->children, sibling) |
3b287a50 TH |
3556 | if (next->serial_nr > pos->serial_nr) |
3557 | break; | |
53fa5261 TH |
3558 | } |
3559 | ||
3b281afb TH |
3560 | /* |
3561 | * @next, if not pointing to the head, can be dereferenced and is | |
c2931b70 | 3562 | * the next sibling. |
3b281afb | 3563 | */ |
c2931b70 TH |
3564 | if (&next->sibling != &parent->children) |
3565 | return next; | |
3b281afb | 3566 | return NULL; |
53fa5261 | 3567 | } |
53fa5261 | 3568 | |
574bd9f7 | 3569 | /** |
492eb21b | 3570 | * css_next_descendant_pre - find the next descendant for pre-order walk |
574bd9f7 | 3571 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3572 | * @root: css whose descendants to walk |
574bd9f7 | 3573 | * |
492eb21b | 3574 | * To be used by css_for_each_descendant_pre(). Find the next descendant |
bd8815a6 TH |
3575 | * to visit for pre-order traversal of @root's descendants. @root is |
3576 | * included in the iteration and the first node to be visited. | |
75501a6d | 3577 | * |
87fb54f1 TH |
3578 | * While this function requires cgroup_mutex or RCU read locking, it |
3579 | * doesn't require the whole traversal to be contained in a single critical | |
3580 | * section. This function will return the correct next descendant as long | |
3581 | * as both @pos and @root are accessible and @pos is a descendant of @root. | |
c2931b70 TH |
3582 | * |
3583 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3584 | * css which finished ->css_online() is guaranteed to be visible in the | |
3585 | * future iterations and will stay visible until the last reference is put. | |
3586 | * A css which hasn't finished ->css_online() or already finished | |
3587 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3588 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3589 | */ |
492eb21b TH |
3590 | struct cgroup_subsys_state * |
3591 | css_next_descendant_pre(struct cgroup_subsys_state *pos, | |
3592 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3593 | { |
492eb21b | 3594 | struct cgroup_subsys_state *next; |
574bd9f7 | 3595 | |
8353da1f | 3596 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3597 | |
bd8815a6 | 3598 | /* if first iteration, visit @root */ |
7805d000 | 3599 | if (!pos) |
bd8815a6 | 3600 | return root; |
574bd9f7 TH |
3601 | |
3602 | /* visit the first child if exists */ | |
492eb21b | 3603 | next = css_next_child(NULL, pos); |
574bd9f7 TH |
3604 | if (next) |
3605 | return next; | |
3606 | ||
3607 | /* no child, visit my or the closest ancestor's next sibling */ | |
492eb21b | 3608 | while (pos != root) { |
5c9d535b | 3609 | next = css_next_child(pos, pos->parent); |
75501a6d | 3610 | if (next) |
574bd9f7 | 3611 | return next; |
5c9d535b | 3612 | pos = pos->parent; |
7805d000 | 3613 | } |
574bd9f7 TH |
3614 | |
3615 | return NULL; | |
3616 | } | |
574bd9f7 | 3617 | |
12a9d2fe | 3618 | /** |
492eb21b TH |
3619 | * css_rightmost_descendant - return the rightmost descendant of a css |
3620 | * @pos: css of interest | |
12a9d2fe | 3621 | * |
492eb21b TH |
3622 | * Return the rightmost descendant of @pos. If there's no descendant, @pos |
3623 | * is returned. This can be used during pre-order traversal to skip | |
12a9d2fe | 3624 | * subtree of @pos. |
75501a6d | 3625 | * |
87fb54f1 TH |
3626 | * While this function requires cgroup_mutex or RCU read locking, it |
3627 | * doesn't require the whole traversal to be contained in a single critical | |
3628 | * section. This function will return the correct rightmost descendant as | |
3629 | * long as @pos is accessible. | |
12a9d2fe | 3630 | */ |
492eb21b TH |
3631 | struct cgroup_subsys_state * |
3632 | css_rightmost_descendant(struct cgroup_subsys_state *pos) | |
12a9d2fe | 3633 | { |
492eb21b | 3634 | struct cgroup_subsys_state *last, *tmp; |
12a9d2fe | 3635 | |
8353da1f | 3636 | cgroup_assert_mutex_or_rcu_locked(); |
12a9d2fe TH |
3637 | |
3638 | do { | |
3639 | last = pos; | |
3640 | /* ->prev isn't RCU safe, walk ->next till the end */ | |
3641 | pos = NULL; | |
492eb21b | 3642 | css_for_each_child(tmp, last) |
12a9d2fe TH |
3643 | pos = tmp; |
3644 | } while (pos); | |
3645 | ||
3646 | return last; | |
3647 | } | |
12a9d2fe | 3648 | |
492eb21b TH |
3649 | static struct cgroup_subsys_state * |
3650 | css_leftmost_descendant(struct cgroup_subsys_state *pos) | |
574bd9f7 | 3651 | { |
492eb21b | 3652 | struct cgroup_subsys_state *last; |
574bd9f7 TH |
3653 | |
3654 | do { | |
3655 | last = pos; | |
492eb21b | 3656 | pos = css_next_child(NULL, pos); |
574bd9f7 TH |
3657 | } while (pos); |
3658 | ||
3659 | return last; | |
3660 | } | |
3661 | ||
3662 | /** | |
492eb21b | 3663 | * css_next_descendant_post - find the next descendant for post-order walk |
574bd9f7 | 3664 | * @pos: the current position (%NULL to initiate traversal) |
492eb21b | 3665 | * @root: css whose descendants to walk |
574bd9f7 | 3666 | * |
492eb21b | 3667 | * To be used by css_for_each_descendant_post(). Find the next descendant |
bd8815a6 TH |
3668 | * to visit for post-order traversal of @root's descendants. @root is |
3669 | * included in the iteration and the last node to be visited. | |
75501a6d | 3670 | * |
87fb54f1 TH |
3671 | * While this function requires cgroup_mutex or RCU read locking, it |
3672 | * doesn't require the whole traversal to be contained in a single critical | |
3673 | * section. This function will return the correct next descendant as long | |
3674 | * as both @pos and @cgroup are accessible and @pos is a descendant of | |
3675 | * @cgroup. | |
c2931b70 TH |
3676 | * |
3677 | * If a subsystem synchronizes ->css_online() and the start of iteration, a | |
3678 | * css which finished ->css_online() is guaranteed to be visible in the | |
3679 | * future iterations and will stay visible until the last reference is put. | |
3680 | * A css which hasn't finished ->css_online() or already finished | |
3681 | * ->css_offline() may show up during traversal. It's each subsystem's | |
3682 | * responsibility to synchronize against on/offlining. | |
574bd9f7 | 3683 | */ |
492eb21b TH |
3684 | struct cgroup_subsys_state * |
3685 | css_next_descendant_post(struct cgroup_subsys_state *pos, | |
3686 | struct cgroup_subsys_state *root) | |
574bd9f7 | 3687 | { |
492eb21b | 3688 | struct cgroup_subsys_state *next; |
574bd9f7 | 3689 | |
8353da1f | 3690 | cgroup_assert_mutex_or_rcu_locked(); |
574bd9f7 | 3691 | |
58b79a91 TH |
3692 | /* if first iteration, visit leftmost descendant which may be @root */ |
3693 | if (!pos) | |
3694 | return css_leftmost_descendant(root); | |
574bd9f7 | 3695 | |
bd8815a6 TH |
3696 | /* if we visited @root, we're done */ |
3697 | if (pos == root) | |
3698 | return NULL; | |
3699 | ||
574bd9f7 | 3700 | /* if there's an unvisited sibling, visit its leftmost descendant */ |
5c9d535b | 3701 | next = css_next_child(pos, pos->parent); |
75501a6d | 3702 | if (next) |
492eb21b | 3703 | return css_leftmost_descendant(next); |
574bd9f7 TH |
3704 | |
3705 | /* no sibling left, visit parent */ | |
5c9d535b | 3706 | return pos->parent; |
574bd9f7 | 3707 | } |
574bd9f7 | 3708 | |
f3d46500 TH |
3709 | /** |
3710 | * css_has_online_children - does a css have online children | |
3711 | * @css: the target css | |
3712 | * | |
3713 | * Returns %true if @css has any online children; otherwise, %false. This | |
3714 | * function can be called from any context but the caller is responsible | |
3715 | * for synchronizing against on/offlining as necessary. | |
3716 | */ | |
3717 | bool css_has_online_children(struct cgroup_subsys_state *css) | |
cbc125ef | 3718 | { |
f3d46500 TH |
3719 | struct cgroup_subsys_state *child; |
3720 | bool ret = false; | |
cbc125ef TH |
3721 | |
3722 | rcu_read_lock(); | |
f3d46500 | 3723 | css_for_each_child(child, css) { |
99bae5f9 | 3724 | if (child->flags & CSS_ONLINE) { |
f3d46500 TH |
3725 | ret = true; |
3726 | break; | |
cbc125ef TH |
3727 | } |
3728 | } | |
3729 | rcu_read_unlock(); | |
f3d46500 | 3730 | return ret; |
574bd9f7 | 3731 | } |
574bd9f7 | 3732 | |
0942eeee | 3733 | /** |
72ec7029 | 3734 | * css_advance_task_iter - advance a task itererator to the next css_set |
0942eeee TH |
3735 | * @it: the iterator to advance |
3736 | * | |
3737 | * Advance @it to the next css_set to walk. | |
d515876e | 3738 | */ |
72ec7029 | 3739 | static void css_advance_task_iter(struct css_task_iter *it) |
d515876e | 3740 | { |
0f0a2b4f | 3741 | struct list_head *l = it->cset_pos; |
d515876e TH |
3742 | struct cgrp_cset_link *link; |
3743 | struct css_set *cset; | |
3744 | ||
3745 | /* Advance to the next non-empty css_set */ | |
3746 | do { | |
3747 | l = l->next; | |
0f0a2b4f TH |
3748 | if (l == it->cset_head) { |
3749 | it->cset_pos = NULL; | |
d515876e TH |
3750 | return; |
3751 | } | |
3ebb2b6e TH |
3752 | |
3753 | if (it->ss) { | |
3754 | cset = container_of(l, struct css_set, | |
3755 | e_cset_node[it->ss->id]); | |
3756 | } else { | |
3757 | link = list_entry(l, struct cgrp_cset_link, cset_link); | |
3758 | cset = link->cset; | |
3759 | } | |
c7561128 TH |
3760 | } while (list_empty(&cset->tasks) && list_empty(&cset->mg_tasks)); |
3761 | ||
0f0a2b4f | 3762 | it->cset_pos = l; |
c7561128 TH |
3763 | |
3764 | if (!list_empty(&cset->tasks)) | |
0f0a2b4f | 3765 | it->task_pos = cset->tasks.next; |
c7561128 | 3766 | else |
0f0a2b4f TH |
3767 | it->task_pos = cset->mg_tasks.next; |
3768 | ||
3769 | it->tasks_head = &cset->tasks; | |
3770 | it->mg_tasks_head = &cset->mg_tasks; | |
d515876e TH |
3771 | } |
3772 | ||
0942eeee | 3773 | /** |
72ec7029 TH |
3774 | * css_task_iter_start - initiate task iteration |
3775 | * @css: the css to walk tasks of | |
0942eeee TH |
3776 | * @it: the task iterator to use |
3777 | * | |
72ec7029 TH |
3778 | * Initiate iteration through the tasks of @css. The caller can call |
3779 | * css_task_iter_next() to walk through the tasks until the function | |
3780 | * returns NULL. On completion of iteration, css_task_iter_end() must be | |
3781 | * called. | |
0942eeee TH |
3782 | * |
3783 | * Note that this function acquires a lock which is released when the | |
3784 | * iteration finishes. The caller can't sleep while iteration is in | |
3785 | * progress. | |
3786 | */ | |
72ec7029 TH |
3787 | void css_task_iter_start(struct cgroup_subsys_state *css, |
3788 | struct css_task_iter *it) | |
96d365e0 | 3789 | __acquires(css_set_rwsem) |
817929ec | 3790 | { |
56fde9e0 TH |
3791 | /* no one should try to iterate before mounting cgroups */ |
3792 | WARN_ON_ONCE(!use_task_css_set_links); | |
31a7df01 | 3793 | |
96d365e0 | 3794 | down_read(&css_set_rwsem); |
c59cd3d8 | 3795 | |
3ebb2b6e TH |
3796 | it->ss = css->ss; |
3797 | ||
3798 | if (it->ss) | |
3799 | it->cset_pos = &css->cgroup->e_csets[css->ss->id]; | |
3800 | else | |
3801 | it->cset_pos = &css->cgroup->cset_links; | |
3802 | ||
0f0a2b4f | 3803 | it->cset_head = it->cset_pos; |
c59cd3d8 | 3804 | |
72ec7029 | 3805 | css_advance_task_iter(it); |
817929ec PM |
3806 | } |
3807 | ||
0942eeee | 3808 | /** |
72ec7029 | 3809 | * css_task_iter_next - return the next task for the iterator |
0942eeee TH |
3810 | * @it: the task iterator being iterated |
3811 | * | |
3812 | * The "next" function for task iteration. @it should have been | |
72ec7029 TH |
3813 | * initialized via css_task_iter_start(). Returns NULL when the iteration |
3814 | * reaches the end. | |
0942eeee | 3815 | */ |
72ec7029 | 3816 | struct task_struct *css_task_iter_next(struct css_task_iter *it) |
817929ec PM |
3817 | { |
3818 | struct task_struct *res; | |
0f0a2b4f | 3819 | struct list_head *l = it->task_pos; |
817929ec PM |
3820 | |
3821 | /* If the iterator cg is NULL, we have no tasks */ | |
0f0a2b4f | 3822 | if (!it->cset_pos) |
817929ec PM |
3823 | return NULL; |
3824 | res = list_entry(l, struct task_struct, cg_list); | |
c7561128 TH |
3825 | |
3826 | /* | |
3827 | * Advance iterator to find next entry. cset->tasks is consumed | |
3828 | * first and then ->mg_tasks. After ->mg_tasks, we move onto the | |
3829 | * next cset. | |
3830 | */ | |
817929ec | 3831 | l = l->next; |
c7561128 | 3832 | |
0f0a2b4f TH |
3833 | if (l == it->tasks_head) |
3834 | l = it->mg_tasks_head->next; | |
c7561128 | 3835 | |
0f0a2b4f | 3836 | if (l == it->mg_tasks_head) |
72ec7029 | 3837 | css_advance_task_iter(it); |
c7561128 | 3838 | else |
0f0a2b4f | 3839 | it->task_pos = l; |
c7561128 | 3840 | |
817929ec PM |
3841 | return res; |
3842 | } | |
3843 | ||
0942eeee | 3844 | /** |
72ec7029 | 3845 | * css_task_iter_end - finish task iteration |
0942eeee TH |
3846 | * @it: the task iterator to finish |
3847 | * | |
72ec7029 | 3848 | * Finish task iteration started by css_task_iter_start(). |
0942eeee | 3849 | */ |
72ec7029 | 3850 | void css_task_iter_end(struct css_task_iter *it) |
96d365e0 | 3851 | __releases(css_set_rwsem) |
31a7df01 | 3852 | { |
96d365e0 | 3853 | up_read(&css_set_rwsem); |
31a7df01 CW |
3854 | } |
3855 | ||
3856 | /** | |
8cc99345 TH |
3857 | * cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
3858 | * @to: cgroup to which the tasks will be moved | |
3859 | * @from: cgroup in which the tasks currently reside | |
31a7df01 | 3860 | * |
eaf797ab TH |
3861 | * Locking rules between cgroup_post_fork() and the migration path |
3862 | * guarantee that, if a task is forking while being migrated, the new child | |
3863 | * is guaranteed to be either visible in the source cgroup after the | |
3864 | * parent's migration is complete or put into the target cgroup. No task | |
3865 | * can slip out of migration through forking. | |
31a7df01 | 3866 | */ |
8cc99345 | 3867 | int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
31a7df01 | 3868 | { |
952aaa12 TH |
3869 | LIST_HEAD(preloaded_csets); |
3870 | struct cgrp_cset_link *link; | |
72ec7029 | 3871 | struct css_task_iter it; |
e406d1cf | 3872 | struct task_struct *task; |
952aaa12 | 3873 | int ret; |
31a7df01 | 3874 | |
952aaa12 | 3875 | mutex_lock(&cgroup_mutex); |
31a7df01 | 3876 | |
952aaa12 TH |
3877 | /* all tasks in @from are being moved, all csets are source */ |
3878 | down_read(&css_set_rwsem); | |
3879 | list_for_each_entry(link, &from->cset_links, cset_link) | |
3880 | cgroup_migrate_add_src(link->cset, to, &preloaded_csets); | |
3881 | up_read(&css_set_rwsem); | |
31a7df01 | 3882 | |
952aaa12 TH |
3883 | ret = cgroup_migrate_prepare_dst(to, &preloaded_csets); |
3884 | if (ret) | |
3885 | goto out_err; | |
8cc99345 | 3886 | |
952aaa12 TH |
3887 | /* |
3888 | * Migrate tasks one-by-one until @form is empty. This fails iff | |
3889 | * ->can_attach() fails. | |
3890 | */ | |
e406d1cf | 3891 | do { |
9d800df1 | 3892 | css_task_iter_start(&from->self, &it); |
e406d1cf TH |
3893 | task = css_task_iter_next(&it); |
3894 | if (task) | |
3895 | get_task_struct(task); | |
3896 | css_task_iter_end(&it); | |
3897 | ||
3898 | if (task) { | |
952aaa12 | 3899 | ret = cgroup_migrate(to, task, false); |
e406d1cf TH |
3900 | put_task_struct(task); |
3901 | } | |
3902 | } while (task && !ret); | |
952aaa12 TH |
3903 | out_err: |
3904 | cgroup_migrate_finish(&preloaded_csets); | |
47cfcd09 | 3905 | mutex_unlock(&cgroup_mutex); |
e406d1cf | 3906 | return ret; |
8cc99345 TH |
3907 | } |
3908 | ||
bbcb81d0 | 3909 | /* |
102a775e | 3910 | * Stuff for reading the 'tasks'/'procs' files. |
bbcb81d0 PM |
3911 | * |
3912 | * Reading this file can return large amounts of data if a cgroup has | |
3913 | * *lots* of attached tasks. So it may need several calls to read(), | |
3914 | * but we cannot guarantee that the information we produce is correct | |
3915 | * unless we produce it entirely atomically. | |
3916 | * | |
bbcb81d0 | 3917 | */ |
bbcb81d0 | 3918 | |
24528255 LZ |
3919 | /* which pidlist file are we talking about? */ |
3920 | enum cgroup_filetype { | |
3921 | CGROUP_FILE_PROCS, | |
3922 | CGROUP_FILE_TASKS, | |
3923 | }; | |
3924 | ||
3925 | /* | |
3926 | * A pidlist is a list of pids that virtually represents the contents of one | |
3927 | * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, | |
3928 | * a pair (one each for procs, tasks) for each pid namespace that's relevant | |
3929 | * to the cgroup. | |
3930 | */ | |
3931 | struct cgroup_pidlist { | |
3932 | /* | |
3933 | * used to find which pidlist is wanted. doesn't change as long as | |
3934 | * this particular list stays in the list. | |
3935 | */ | |
3936 | struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; | |
3937 | /* array of xids */ | |
3938 | pid_t *list; | |
3939 | /* how many elements the above list has */ | |
3940 | int length; | |
24528255 LZ |
3941 | /* each of these stored in a list by its cgroup */ |
3942 | struct list_head links; | |
3943 | /* pointer to the cgroup we belong to, for list removal purposes */ | |
3944 | struct cgroup *owner; | |
b1a21367 TH |
3945 | /* for delayed destruction */ |
3946 | struct delayed_work destroy_dwork; | |
24528255 LZ |
3947 | }; |
3948 | ||
d1d9fd33 BB |
3949 | /* |
3950 | * The following two functions "fix" the issue where there are more pids | |
3951 | * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. | |
3952 | * TODO: replace with a kernel-wide solution to this problem | |
3953 | */ | |
3954 | #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) | |
3955 | static void *pidlist_allocate(int count) | |
3956 | { | |
3957 | if (PIDLIST_TOO_LARGE(count)) | |
3958 | return vmalloc(count * sizeof(pid_t)); | |
3959 | else | |
3960 | return kmalloc(count * sizeof(pid_t), GFP_KERNEL); | |
3961 | } | |
b1a21367 | 3962 | |
d1d9fd33 BB |
3963 | static void pidlist_free(void *p) |
3964 | { | |
58794514 | 3965 | kvfree(p); |
d1d9fd33 | 3966 | } |
d1d9fd33 | 3967 | |
b1a21367 TH |
3968 | /* |
3969 | * Used to destroy all pidlists lingering waiting for destroy timer. None | |
3970 | * should be left afterwards. | |
3971 | */ | |
3972 | static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) | |
3973 | { | |
3974 | struct cgroup_pidlist *l, *tmp_l; | |
3975 | ||
3976 | mutex_lock(&cgrp->pidlist_mutex); | |
3977 | list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) | |
3978 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); | |
3979 | mutex_unlock(&cgrp->pidlist_mutex); | |
3980 | ||
3981 | flush_workqueue(cgroup_pidlist_destroy_wq); | |
3982 | BUG_ON(!list_empty(&cgrp->pidlists)); | |
3983 | } | |
3984 | ||
3985 | static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) | |
3986 | { | |
3987 | struct delayed_work *dwork = to_delayed_work(work); | |
3988 | struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, | |
3989 | destroy_dwork); | |
3990 | struct cgroup_pidlist *tofree = NULL; | |
3991 | ||
3992 | mutex_lock(&l->owner->pidlist_mutex); | |
b1a21367 TH |
3993 | |
3994 | /* | |
04502365 TH |
3995 | * Destroy iff we didn't get queued again. The state won't change |
3996 | * as destroy_dwork can only be queued while locked. | |
b1a21367 | 3997 | */ |
04502365 | 3998 | if (!delayed_work_pending(dwork)) { |
b1a21367 TH |
3999 | list_del(&l->links); |
4000 | pidlist_free(l->list); | |
4001 | put_pid_ns(l->key.ns); | |
4002 | tofree = l; | |
4003 | } | |
4004 | ||
b1a21367 TH |
4005 | mutex_unlock(&l->owner->pidlist_mutex); |
4006 | kfree(tofree); | |
4007 | } | |
4008 | ||
bbcb81d0 | 4009 | /* |
102a775e | 4010 | * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
6ee211ad | 4011 | * Returns the number of unique elements. |
bbcb81d0 | 4012 | */ |
6ee211ad | 4013 | static int pidlist_uniq(pid_t *list, int length) |
bbcb81d0 | 4014 | { |
102a775e | 4015 | int src, dest = 1; |
102a775e BB |
4016 | |
4017 | /* | |
4018 | * we presume the 0th element is unique, so i starts at 1. trivial | |
4019 | * edge cases first; no work needs to be done for either | |
4020 | */ | |
4021 | if (length == 0 || length == 1) | |
4022 | return length; | |
4023 | /* src and dest walk down the list; dest counts unique elements */ | |
4024 | for (src = 1; src < length; src++) { | |
4025 | /* find next unique element */ | |
4026 | while (list[src] == list[src-1]) { | |
4027 | src++; | |
4028 | if (src == length) | |
4029 | goto after; | |
4030 | } | |
4031 | /* dest always points to where the next unique element goes */ | |
4032 | list[dest] = list[src]; | |
4033 | dest++; | |
4034 | } | |
4035 | after: | |
102a775e BB |
4036 | return dest; |
4037 | } | |
4038 | ||
afb2bc14 TH |
4039 | /* |
4040 | * The two pid files - task and cgroup.procs - guaranteed that the result | |
4041 | * is sorted, which forced this whole pidlist fiasco. As pid order is | |
4042 | * different per namespace, each namespace needs differently sorted list, | |
4043 | * making it impossible to use, for example, single rbtree of member tasks | |
4044 | * sorted by task pointer. As pidlists can be fairly large, allocating one | |
4045 | * per open file is dangerous, so cgroup had to implement shared pool of | |
4046 | * pidlists keyed by cgroup and namespace. | |
4047 | * | |
4048 | * All this extra complexity was caused by the original implementation | |
4049 | * committing to an entirely unnecessary property. In the long term, we | |
aa6ec29b TH |
4050 | * want to do away with it. Explicitly scramble sort order if on the |
4051 | * default hierarchy so that no such expectation exists in the new | |
4052 | * interface. | |
afb2bc14 TH |
4053 | * |
4054 | * Scrambling is done by swapping every two consecutive bits, which is | |
4055 | * non-identity one-to-one mapping which disturbs sort order sufficiently. | |
4056 | */ | |
4057 | static pid_t pid_fry(pid_t pid) | |
4058 | { | |
4059 | unsigned a = pid & 0x55555555; | |
4060 | unsigned b = pid & 0xAAAAAAAA; | |
4061 | ||
4062 | return (a << 1) | (b >> 1); | |
4063 | } | |
4064 | ||
4065 | static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) | |
4066 | { | |
aa6ec29b | 4067 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4068 | return pid_fry(pid); |
4069 | else | |
4070 | return pid; | |
4071 | } | |
4072 | ||
102a775e BB |
4073 | static int cmppid(const void *a, const void *b) |
4074 | { | |
4075 | return *(pid_t *)a - *(pid_t *)b; | |
4076 | } | |
4077 | ||
afb2bc14 TH |
4078 | static int fried_cmppid(const void *a, const void *b) |
4079 | { | |
4080 | return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); | |
4081 | } | |
4082 | ||
e6b81710 TH |
4083 | static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
4084 | enum cgroup_filetype type) | |
4085 | { | |
4086 | struct cgroup_pidlist *l; | |
4087 | /* don't need task_nsproxy() if we're looking at ourself */ | |
4088 | struct pid_namespace *ns = task_active_pid_ns(current); | |
4089 | ||
4090 | lockdep_assert_held(&cgrp->pidlist_mutex); | |
4091 | ||
4092 | list_for_each_entry(l, &cgrp->pidlists, links) | |
4093 | if (l->key.type == type && l->key.ns == ns) | |
4094 | return l; | |
4095 | return NULL; | |
4096 | } | |
4097 | ||
72a8cb30 BB |
4098 | /* |
4099 | * find the appropriate pidlist for our purpose (given procs vs tasks) | |
4100 | * returns with the lock on that pidlist already held, and takes care | |
4101 | * of the use count, or returns NULL with no locks held if we're out of | |
4102 | * memory. | |
4103 | */ | |
e6b81710 TH |
4104 | static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
4105 | enum cgroup_filetype type) | |
72a8cb30 BB |
4106 | { |
4107 | struct cgroup_pidlist *l; | |
b70cc5fd | 4108 | |
e6b81710 TH |
4109 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4110 | ||
4111 | l = cgroup_pidlist_find(cgrp, type); | |
4112 | if (l) | |
4113 | return l; | |
4114 | ||
72a8cb30 | 4115 | /* entry not found; create a new one */ |
f4f4be2b | 4116 | l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
e6b81710 | 4117 | if (!l) |
72a8cb30 | 4118 | return l; |
e6b81710 | 4119 | |
b1a21367 | 4120 | INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
72a8cb30 | 4121 | l->key.type = type; |
e6b81710 TH |
4122 | /* don't need task_nsproxy() if we're looking at ourself */ |
4123 | l->key.ns = get_pid_ns(task_active_pid_ns(current)); | |
72a8cb30 BB |
4124 | l->owner = cgrp; |
4125 | list_add(&l->links, &cgrp->pidlists); | |
72a8cb30 BB |
4126 | return l; |
4127 | } | |
4128 | ||
102a775e BB |
4129 | /* |
4130 | * Load a cgroup's pidarray with either procs' tgids or tasks' pids | |
4131 | */ | |
72a8cb30 BB |
4132 | static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
4133 | struct cgroup_pidlist **lp) | |
102a775e BB |
4134 | { |
4135 | pid_t *array; | |
4136 | int length; | |
4137 | int pid, n = 0; /* used for populating the array */ | |
72ec7029 | 4138 | struct css_task_iter it; |
817929ec | 4139 | struct task_struct *tsk; |
102a775e BB |
4140 | struct cgroup_pidlist *l; |
4141 | ||
4bac00d1 TH |
4142 | lockdep_assert_held(&cgrp->pidlist_mutex); |
4143 | ||
102a775e BB |
4144 | /* |
4145 | * If cgroup gets more users after we read count, we won't have | |
4146 | * enough space - tough. This race is indistinguishable to the | |
4147 | * caller from the case that the additional cgroup users didn't | |
4148 | * show up until sometime later on. | |
4149 | */ | |
4150 | length = cgroup_task_count(cgrp); | |
d1d9fd33 | 4151 | array = pidlist_allocate(length); |
102a775e BB |
4152 | if (!array) |
4153 | return -ENOMEM; | |
4154 | /* now, populate the array */ | |
9d800df1 | 4155 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4156 | while ((tsk = css_task_iter_next(&it))) { |
102a775e | 4157 | if (unlikely(n == length)) |
817929ec | 4158 | break; |
102a775e | 4159 | /* get tgid or pid for procs or tasks file respectively */ |
72a8cb30 BB |
4160 | if (type == CGROUP_FILE_PROCS) |
4161 | pid = task_tgid_vnr(tsk); | |
4162 | else | |
4163 | pid = task_pid_vnr(tsk); | |
102a775e BB |
4164 | if (pid > 0) /* make sure to only use valid results */ |
4165 | array[n++] = pid; | |
817929ec | 4166 | } |
72ec7029 | 4167 | css_task_iter_end(&it); |
102a775e BB |
4168 | length = n; |
4169 | /* now sort & (if procs) strip out duplicates */ | |
aa6ec29b | 4170 | if (cgroup_on_dfl(cgrp)) |
afb2bc14 TH |
4171 | sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
4172 | else | |
4173 | sort(array, length, sizeof(pid_t), cmppid, NULL); | |
72a8cb30 | 4174 | if (type == CGROUP_FILE_PROCS) |
6ee211ad | 4175 | length = pidlist_uniq(array, length); |
e6b81710 | 4176 | |
e6b81710 | 4177 | l = cgroup_pidlist_find_create(cgrp, type); |
72a8cb30 | 4178 | if (!l) { |
d1d9fd33 | 4179 | pidlist_free(array); |
72a8cb30 | 4180 | return -ENOMEM; |
102a775e | 4181 | } |
e6b81710 TH |
4182 | |
4183 | /* store array, freeing old if necessary */ | |
d1d9fd33 | 4184 | pidlist_free(l->list); |
102a775e BB |
4185 | l->list = array; |
4186 | l->length = length; | |
72a8cb30 | 4187 | *lp = l; |
102a775e | 4188 | return 0; |
bbcb81d0 PM |
4189 | } |
4190 | ||
846c7bb0 | 4191 | /** |
a043e3b2 | 4192 | * cgroupstats_build - build and fill cgroupstats |
846c7bb0 BS |
4193 | * @stats: cgroupstats to fill information into |
4194 | * @dentry: A dentry entry belonging to the cgroup for which stats have | |
4195 | * been requested. | |
a043e3b2 LZ |
4196 | * |
4197 | * Build and fill cgroupstats so that taskstats can export it to user | |
4198 | * space. | |
846c7bb0 BS |
4199 | */ |
4200 | int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) | |
4201 | { | |
2bd59d48 | 4202 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
bd89aabc | 4203 | struct cgroup *cgrp; |
72ec7029 | 4204 | struct css_task_iter it; |
846c7bb0 | 4205 | struct task_struct *tsk; |
33d283be | 4206 | |
2bd59d48 TH |
4207 | /* it should be kernfs_node belonging to cgroupfs and is a directory */ |
4208 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || | |
4209 | kernfs_type(kn) != KERNFS_DIR) | |
4210 | return -EINVAL; | |
4211 | ||
bad34660 LZ |
4212 | mutex_lock(&cgroup_mutex); |
4213 | ||
846c7bb0 | 4214 | /* |
2bd59d48 | 4215 | * We aren't being called from kernfs and there's no guarantee on |
ec903c0c | 4216 | * @kn->priv's validity. For this and css_tryget_online_from_dir(), |
2bd59d48 | 4217 | * @kn->priv is RCU safe. Let's do the RCU dancing. |
846c7bb0 | 4218 | */ |
2bd59d48 TH |
4219 | rcu_read_lock(); |
4220 | cgrp = rcu_dereference(kn->priv); | |
bad34660 | 4221 | if (!cgrp || cgroup_is_dead(cgrp)) { |
2bd59d48 | 4222 | rcu_read_unlock(); |
bad34660 | 4223 | mutex_unlock(&cgroup_mutex); |
2bd59d48 TH |
4224 | return -ENOENT; |
4225 | } | |
bad34660 | 4226 | rcu_read_unlock(); |
846c7bb0 | 4227 | |
9d800df1 | 4228 | css_task_iter_start(&cgrp->self, &it); |
72ec7029 | 4229 | while ((tsk = css_task_iter_next(&it))) { |
846c7bb0 BS |
4230 | switch (tsk->state) { |
4231 | case TASK_RUNNING: | |
4232 | stats->nr_running++; | |
4233 | break; | |
4234 | case TASK_INTERRUPTIBLE: | |
4235 | stats->nr_sleeping++; | |
4236 | break; | |
4237 | case TASK_UNINTERRUPTIBLE: | |
4238 | stats->nr_uninterruptible++; | |
4239 | break; | |
4240 | case TASK_STOPPED: | |
4241 | stats->nr_stopped++; | |
4242 | break; | |
4243 | default: | |
4244 | if (delayacct_is_task_waiting_on_io(tsk)) | |
4245 | stats->nr_io_wait++; | |
4246 | break; | |
4247 | } | |
4248 | } | |
72ec7029 | 4249 | css_task_iter_end(&it); |
846c7bb0 | 4250 | |
bad34660 | 4251 | mutex_unlock(&cgroup_mutex); |
2bd59d48 | 4252 | return 0; |
846c7bb0 BS |
4253 | } |
4254 | ||
8f3ff208 | 4255 | |
bbcb81d0 | 4256 | /* |
102a775e | 4257 | * seq_file methods for the tasks/procs files. The seq_file position is the |
cc31edce | 4258 | * next pid to display; the seq_file iterator is a pointer to the pid |
102a775e | 4259 | * in the cgroup->l->list array. |
bbcb81d0 | 4260 | */ |
cc31edce | 4261 | |
102a775e | 4262 | static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
bbcb81d0 | 4263 | { |
cc31edce PM |
4264 | /* |
4265 | * Initially we receive a position value that corresponds to | |
4266 | * one more than the last pid shown (or 0 on the first call or | |
4267 | * after a seek to the start). Use a binary-search to find the | |
4268 | * next pid to display, if any | |
4269 | */ | |
2bd59d48 | 4270 | struct kernfs_open_file *of = s->private; |
7da11279 | 4271 | struct cgroup *cgrp = seq_css(s)->cgroup; |
4bac00d1 | 4272 | struct cgroup_pidlist *l; |
7da11279 | 4273 | enum cgroup_filetype type = seq_cft(s)->private; |
cc31edce | 4274 | int index = 0, pid = *pos; |
4bac00d1 TH |
4275 | int *iter, ret; |
4276 | ||
4277 | mutex_lock(&cgrp->pidlist_mutex); | |
4278 | ||
4279 | /* | |
5d22444f | 4280 | * !NULL @of->priv indicates that this isn't the first start() |
4bac00d1 | 4281 | * after open. If the matching pidlist is around, we can use that. |
5d22444f | 4282 | * Look for it. Note that @of->priv can't be used directly. It |
4bac00d1 TH |
4283 | * could already have been destroyed. |
4284 | */ | |
5d22444f TH |
4285 | if (of->priv) |
4286 | of->priv = cgroup_pidlist_find(cgrp, type); | |
4bac00d1 TH |
4287 | |
4288 | /* | |
4289 | * Either this is the first start() after open or the matching | |
4290 | * pidlist has been destroyed inbetween. Create a new one. | |
4291 | */ | |
5d22444f TH |
4292 | if (!of->priv) { |
4293 | ret = pidlist_array_load(cgrp, type, | |
4294 | (struct cgroup_pidlist **)&of->priv); | |
4bac00d1 TH |
4295 | if (ret) |
4296 | return ERR_PTR(ret); | |
4297 | } | |
5d22444f | 4298 | l = of->priv; |
cc31edce | 4299 | |
cc31edce | 4300 | if (pid) { |
102a775e | 4301 | int end = l->length; |
20777766 | 4302 | |
cc31edce PM |
4303 | while (index < end) { |
4304 | int mid = (index + end) / 2; | |
afb2bc14 | 4305 | if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
cc31edce PM |
4306 | index = mid; |
4307 | break; | |
afb2bc14 | 4308 | } else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
cc31edce PM |
4309 | index = mid + 1; |
4310 | else | |
4311 | end = mid; | |
4312 | } | |
4313 | } | |
4314 | /* If we're off the end of the array, we're done */ | |
102a775e | 4315 | if (index >= l->length) |
cc31edce PM |
4316 | return NULL; |
4317 | /* Update the abstract position to be the actual pid that we found */ | |
102a775e | 4318 | iter = l->list + index; |
afb2bc14 | 4319 | *pos = cgroup_pid_fry(cgrp, *iter); |
cc31edce PM |
4320 | return iter; |
4321 | } | |
4322 | ||
102a775e | 4323 | static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
cc31edce | 4324 | { |
2bd59d48 | 4325 | struct kernfs_open_file *of = s->private; |
5d22444f | 4326 | struct cgroup_pidlist *l = of->priv; |
62236858 | 4327 | |
5d22444f TH |
4328 | if (l) |
4329 | mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, | |
04502365 | 4330 | CGROUP_PIDLIST_DESTROY_DELAY); |
7da11279 | 4331 | mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
cc31edce PM |
4332 | } |
4333 | ||
102a775e | 4334 | static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
cc31edce | 4335 | { |
2bd59d48 | 4336 | struct kernfs_open_file *of = s->private; |
5d22444f | 4337 | struct cgroup_pidlist *l = of->priv; |
102a775e BB |
4338 | pid_t *p = v; |
4339 | pid_t *end = l->list + l->length; | |
cc31edce PM |
4340 | /* |
4341 | * Advance to the next pid in the array. If this goes off the | |
4342 | * end, we're done | |
4343 | */ | |
4344 | p++; | |
4345 | if (p >= end) { | |
4346 | return NULL; | |
4347 | } else { | |
7da11279 | 4348 | *pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
cc31edce PM |
4349 | return p; |
4350 | } | |
4351 | } | |
4352 | ||
102a775e | 4353 | static int cgroup_pidlist_show(struct seq_file *s, void *v) |
cc31edce | 4354 | { |
94ff212d JP |
4355 | seq_printf(s, "%d\n", *(int *)v); |
4356 | ||
4357 | return 0; | |
cc31edce | 4358 | } |
bbcb81d0 | 4359 | |
182446d0 TH |
4360 | static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
4361 | struct cftype *cft) | |
81a6a5cd | 4362 | { |
182446d0 | 4363 | return notify_on_release(css->cgroup); |
81a6a5cd PM |
4364 | } |
4365 | ||
182446d0 TH |
4366 | static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
4367 | struct cftype *cft, u64 val) | |
6379c106 | 4368 | { |
6379c106 | 4369 | if (val) |
182446d0 | 4370 | set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 | 4371 | else |
182446d0 | 4372 | clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
6379c106 PM |
4373 | return 0; |
4374 | } | |
4375 | ||
182446d0 TH |
4376 | static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
4377 | struct cftype *cft) | |
97978e6d | 4378 | { |
182446d0 | 4379 | return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4380 | } |
4381 | ||
182446d0 TH |
4382 | static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
4383 | struct cftype *cft, u64 val) | |
97978e6d DL |
4384 | { |
4385 | if (val) | |
182446d0 | 4386 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d | 4387 | else |
182446d0 | 4388 | clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
97978e6d DL |
4389 | return 0; |
4390 | } | |
4391 | ||
a14c6874 TH |
4392 | /* cgroup core interface files for the default hierarchy */ |
4393 | static struct cftype cgroup_dfl_base_files[] = { | |
81a6a5cd | 4394 | { |
d5c56ced | 4395 | .name = "cgroup.procs", |
6612f05b TH |
4396 | .seq_start = cgroup_pidlist_start, |
4397 | .seq_next = cgroup_pidlist_next, | |
4398 | .seq_stop = cgroup_pidlist_stop, | |
4399 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4400 | .private = CGROUP_FILE_PROCS, |
acbef755 | 4401 | .write = cgroup_procs_write, |
102a775e | 4402 | }, |
f8f22e53 TH |
4403 | { |
4404 | .name = "cgroup.controllers", | |
a14c6874 | 4405 | .flags = CFTYPE_ONLY_ON_ROOT, |
f8f22e53 TH |
4406 | .seq_show = cgroup_root_controllers_show, |
4407 | }, | |
4408 | { | |
4409 | .name = "cgroup.controllers", | |
a14c6874 | 4410 | .flags = CFTYPE_NOT_ON_ROOT, |
f8f22e53 TH |
4411 | .seq_show = cgroup_controllers_show, |
4412 | }, | |
4413 | { | |
4414 | .name = "cgroup.subtree_control", | |
f8f22e53 | 4415 | .seq_show = cgroup_subtree_control_show, |
451af504 | 4416 | .write = cgroup_subtree_control_write, |
f8f22e53 | 4417 | }, |
842b597e | 4418 | { |
4a07c222 | 4419 | .name = "cgroup.events", |
a14c6874 | 4420 | .flags = CFTYPE_NOT_ON_ROOT, |
4a07c222 | 4421 | .seq_show = cgroup_events_show, |
842b597e | 4422 | }, |
a14c6874 TH |
4423 | { } /* terminate */ |
4424 | }; | |
d5c56ced | 4425 | |
a14c6874 TH |
4426 | /* cgroup core interface files for the legacy hierarchies */ |
4427 | static struct cftype cgroup_legacy_base_files[] = { | |
4428 | { | |
4429 | .name = "cgroup.procs", | |
4430 | .seq_start = cgroup_pidlist_start, | |
4431 | .seq_next = cgroup_pidlist_next, | |
4432 | .seq_stop = cgroup_pidlist_stop, | |
4433 | .seq_show = cgroup_pidlist_show, | |
4434 | .private = CGROUP_FILE_PROCS, | |
4435 | .write = cgroup_procs_write, | |
a14c6874 TH |
4436 | }, |
4437 | { | |
4438 | .name = "cgroup.clone_children", | |
4439 | .read_u64 = cgroup_clone_children_read, | |
4440 | .write_u64 = cgroup_clone_children_write, | |
4441 | }, | |
4442 | { | |
4443 | .name = "cgroup.sane_behavior", | |
4444 | .flags = CFTYPE_ONLY_ON_ROOT, | |
4445 | .seq_show = cgroup_sane_behavior_show, | |
4446 | }, | |
d5c56ced TH |
4447 | { |
4448 | .name = "tasks", | |
6612f05b TH |
4449 | .seq_start = cgroup_pidlist_start, |
4450 | .seq_next = cgroup_pidlist_next, | |
4451 | .seq_stop = cgroup_pidlist_stop, | |
4452 | .seq_show = cgroup_pidlist_show, | |
5d22444f | 4453 | .private = CGROUP_FILE_TASKS, |
acbef755 | 4454 | .write = cgroup_tasks_write, |
d5c56ced TH |
4455 | }, |
4456 | { | |
4457 | .name = "notify_on_release", | |
d5c56ced TH |
4458 | .read_u64 = cgroup_read_notify_on_release, |
4459 | .write_u64 = cgroup_write_notify_on_release, | |
4460 | }, | |
6e6ff25b TH |
4461 | { |
4462 | .name = "release_agent", | |
a14c6874 | 4463 | .flags = CFTYPE_ONLY_ON_ROOT, |
2da8ca82 | 4464 | .seq_show = cgroup_release_agent_show, |
451af504 | 4465 | .write = cgroup_release_agent_write, |
5f469907 | 4466 | .max_write_len = PATH_MAX - 1, |
6e6ff25b | 4467 | }, |
db0416b6 | 4468 | { } /* terminate */ |
bbcb81d0 PM |
4469 | }; |
4470 | ||
0c21ead1 TH |
4471 | /* |
4472 | * css destruction is four-stage process. | |
4473 | * | |
4474 | * 1. Destruction starts. Killing of the percpu_ref is initiated. | |
4475 | * Implemented in kill_css(). | |
4476 | * | |
4477 | * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs | |
ec903c0c TH |
4478 | * and thus css_tryget_online() is guaranteed to fail, the css can be |
4479 | * offlined by invoking offline_css(). After offlining, the base ref is | |
4480 | * put. Implemented in css_killed_work_fn(). | |
0c21ead1 TH |
4481 | * |
4482 | * 3. When the percpu_ref reaches zero, the only possible remaining | |
4483 | * accessors are inside RCU read sections. css_release() schedules the | |
4484 | * RCU callback. | |
4485 | * | |
4486 | * 4. After the grace period, the css can be freed. Implemented in | |
4487 | * css_free_work_fn(). | |
4488 | * | |
4489 | * It is actually hairier because both step 2 and 4 require process context | |
4490 | * and thus involve punting to css->destroy_work adding two additional | |
4491 | * steps to the already complex sequence. | |
4492 | */ | |
35ef10da | 4493 | static void css_free_work_fn(struct work_struct *work) |
48ddbe19 TH |
4494 | { |
4495 | struct cgroup_subsys_state *css = | |
35ef10da | 4496 | container_of(work, struct cgroup_subsys_state, destroy_work); |
01e58659 | 4497 | struct cgroup_subsys *ss = css->ss; |
0c21ead1 | 4498 | struct cgroup *cgrp = css->cgroup; |
48ddbe19 | 4499 | |
9a1049da TH |
4500 | percpu_ref_exit(&css->refcnt); |
4501 | ||
01e58659 | 4502 | if (ss) { |
9d755d33 | 4503 | /* css free path */ |
01e58659 VD |
4504 | int id = css->id; |
4505 | ||
9d755d33 TH |
4506 | if (css->parent) |
4507 | css_put(css->parent); | |
0ae78e0b | 4508 | |
01e58659 VD |
4509 | ss->css_free(css); |
4510 | cgroup_idr_remove(&ss->css_idr, id); | |
9d755d33 TH |
4511 | cgroup_put(cgrp); |
4512 | } else { | |
4513 | /* cgroup free path */ | |
4514 | atomic_dec(&cgrp->root->nr_cgrps); | |
4515 | cgroup_pidlist_destroy_all(cgrp); | |
971ff493 | 4516 | cancel_work_sync(&cgrp->release_agent_work); |
9d755d33 | 4517 | |
d51f39b0 | 4518 | if (cgroup_parent(cgrp)) { |
9d755d33 TH |
4519 | /* |
4520 | * We get a ref to the parent, and put the ref when | |
4521 | * this cgroup is being freed, so it's guaranteed | |
4522 | * that the parent won't be destroyed before its | |
4523 | * children. | |
4524 | */ | |
d51f39b0 | 4525 | cgroup_put(cgroup_parent(cgrp)); |
9d755d33 TH |
4526 | kernfs_put(cgrp->kn); |
4527 | kfree(cgrp); | |
4528 | } else { | |
4529 | /* | |
4530 | * This is root cgroup's refcnt reaching zero, | |
4531 | * which indicates that the root should be | |
4532 | * released. | |
4533 | */ | |
4534 | cgroup_destroy_root(cgrp->root); | |
4535 | } | |
4536 | } | |
48ddbe19 TH |
4537 | } |
4538 | ||
0c21ead1 | 4539 | static void css_free_rcu_fn(struct rcu_head *rcu_head) |
d3daf28d TH |
4540 | { |
4541 | struct cgroup_subsys_state *css = | |
0c21ead1 | 4542 | container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
d3daf28d | 4543 | |
35ef10da | 4544 | INIT_WORK(&css->destroy_work, css_free_work_fn); |
e5fca243 | 4545 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
48ddbe19 TH |
4546 | } |
4547 | ||
25e15d83 | 4548 | static void css_release_work_fn(struct work_struct *work) |
d3daf28d TH |
4549 | { |
4550 | struct cgroup_subsys_state *css = | |
25e15d83 | 4551 | container_of(work, struct cgroup_subsys_state, destroy_work); |
15a4c835 | 4552 | struct cgroup_subsys *ss = css->ss; |
9d755d33 | 4553 | struct cgroup *cgrp = css->cgroup; |
15a4c835 | 4554 | |
1fed1b2e TH |
4555 | mutex_lock(&cgroup_mutex); |
4556 | ||
de3f0341 | 4557 | css->flags |= CSS_RELEASED; |
1fed1b2e TH |
4558 | list_del_rcu(&css->sibling); |
4559 | ||
9d755d33 TH |
4560 | if (ss) { |
4561 | /* css release path */ | |
01e58659 | 4562 | cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
7d172cc8 TH |
4563 | if (ss->css_released) |
4564 | ss->css_released(css); | |
9d755d33 TH |
4565 | } else { |
4566 | /* cgroup release path */ | |
9d755d33 TH |
4567 | cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
4568 | cgrp->id = -1; | |
a4189487 LZ |
4569 | |
4570 | /* | |
4571 | * There are two control paths which try to determine | |
4572 | * cgroup from dentry without going through kernfs - | |
4573 | * cgroupstats_build() and css_tryget_online_from_dir(). | |
4574 | * Those are supported by RCU protecting clearing of | |
4575 | * cgrp->kn->priv backpointer. | |
4576 | */ | |
4577 | RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); | |
9d755d33 | 4578 | } |
d3daf28d | 4579 | |
1fed1b2e TH |
4580 | mutex_unlock(&cgroup_mutex); |
4581 | ||
0c21ead1 | 4582 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
d3daf28d TH |
4583 | } |
4584 | ||
d3daf28d TH |
4585 | static void css_release(struct percpu_ref *ref) |
4586 | { | |
4587 | struct cgroup_subsys_state *css = | |
4588 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4589 | ||
25e15d83 TH |
4590 | INIT_WORK(&css->destroy_work, css_release_work_fn); |
4591 | queue_work(cgroup_destroy_wq, &css->destroy_work); | |
d3daf28d TH |
4592 | } |
4593 | ||
ddfcadab TH |
4594 | static void init_and_link_css(struct cgroup_subsys_state *css, |
4595 | struct cgroup_subsys *ss, struct cgroup *cgrp) | |
ddbcc7e8 | 4596 | { |
0cb51d71 TH |
4597 | lockdep_assert_held(&cgroup_mutex); |
4598 | ||
ddfcadab TH |
4599 | cgroup_get(cgrp); |
4600 | ||
d5c419b6 | 4601 | memset(css, 0, sizeof(*css)); |
bd89aabc | 4602 | css->cgroup = cgrp; |
72c97e54 | 4603 | css->ss = ss; |
d5c419b6 TH |
4604 | INIT_LIST_HEAD(&css->sibling); |
4605 | INIT_LIST_HEAD(&css->children); | |
0cb51d71 | 4606 | css->serial_nr = css_serial_nr_next++; |
0ae78e0b | 4607 | |
d51f39b0 TH |
4608 | if (cgroup_parent(cgrp)) { |
4609 | css->parent = cgroup_css(cgroup_parent(cgrp), ss); | |
ddfcadab | 4610 | css_get(css->parent); |
ddfcadab | 4611 | } |
48ddbe19 | 4612 | |
ca8bdcaf | 4613 | BUG_ON(cgroup_css(cgrp, ss)); |
ddbcc7e8 PM |
4614 | } |
4615 | ||
2a4ac633 | 4616 | /* invoke ->css_online() on a new CSS and mark it online if successful */ |
623f926b | 4617 | static int online_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4618 | { |
623f926b | 4619 | struct cgroup_subsys *ss = css->ss; |
b1929db4 TH |
4620 | int ret = 0; |
4621 | ||
a31f2d3f TH |
4622 | lockdep_assert_held(&cgroup_mutex); |
4623 | ||
92fb9748 | 4624 | if (ss->css_online) |
eb95419b | 4625 | ret = ss->css_online(css); |
ae7f164a | 4626 | if (!ret) { |
eb95419b | 4627 | css->flags |= CSS_ONLINE; |
aec25020 | 4628 | rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
ae7f164a | 4629 | } |
b1929db4 | 4630 | return ret; |
a31f2d3f TH |
4631 | } |
4632 | ||
2a4ac633 | 4633 | /* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
623f926b | 4634 | static void offline_css(struct cgroup_subsys_state *css) |
a31f2d3f | 4635 | { |
623f926b | 4636 | struct cgroup_subsys *ss = css->ss; |
a31f2d3f TH |
4637 | |
4638 | lockdep_assert_held(&cgroup_mutex); | |
4639 | ||
4640 | if (!(css->flags & CSS_ONLINE)) | |
4641 | return; | |
4642 | ||
d7eeac19 | 4643 | if (ss->css_offline) |
eb95419b | 4644 | ss->css_offline(css); |
a31f2d3f | 4645 | |
eb95419b | 4646 | css->flags &= ~CSS_ONLINE; |
e3297803 | 4647 | RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
f8f22e53 TH |
4648 | |
4649 | wake_up_all(&css->cgroup->offline_waitq); | |
a31f2d3f TH |
4650 | } |
4651 | ||
c81c925a TH |
4652 | /** |
4653 | * create_css - create a cgroup_subsys_state | |
4654 | * @cgrp: the cgroup new css will be associated with | |
4655 | * @ss: the subsys of new css | |
f63070d3 | 4656 | * @visible: whether to create control knobs for the new css or not |
c81c925a TH |
4657 | * |
4658 | * Create a new css associated with @cgrp - @ss pair. On success, the new | |
f63070d3 TH |
4659 | * css is online and installed in @cgrp with all interface files created if |
4660 | * @visible. Returns 0 on success, -errno on failure. | |
c81c925a | 4661 | */ |
f63070d3 TH |
4662 | static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, |
4663 | bool visible) | |
c81c925a | 4664 | { |
d51f39b0 | 4665 | struct cgroup *parent = cgroup_parent(cgrp); |
1fed1b2e | 4666 | struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
c81c925a TH |
4667 | struct cgroup_subsys_state *css; |
4668 | int err; | |
4669 | ||
c81c925a TH |
4670 | lockdep_assert_held(&cgroup_mutex); |
4671 | ||
1fed1b2e | 4672 | css = ss->css_alloc(parent_css); |
c81c925a TH |
4673 | if (IS_ERR(css)) |
4674 | return PTR_ERR(css); | |
4675 | ||
ddfcadab | 4676 | init_and_link_css(css, ss, cgrp); |
a2bed820 | 4677 | |
2aad2a86 | 4678 | err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
c81c925a | 4679 | if (err) |
3eb59ec6 | 4680 | goto err_free_css; |
c81c925a | 4681 | |
cf780b7d | 4682 | err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
15a4c835 TH |
4683 | if (err < 0) |
4684 | goto err_free_percpu_ref; | |
4685 | css->id = err; | |
c81c925a | 4686 | |
f63070d3 TH |
4687 | if (visible) { |
4688 | err = cgroup_populate_dir(cgrp, 1 << ss->id); | |
4689 | if (err) | |
4690 | goto err_free_id; | |
4691 | } | |
15a4c835 TH |
4692 | |
4693 | /* @css is ready to be brought online now, make it visible */ | |
1fed1b2e | 4694 | list_add_tail_rcu(&css->sibling, &parent_css->children); |
15a4c835 | 4695 | cgroup_idr_replace(&ss->css_idr, css, css->id); |
c81c925a TH |
4696 | |
4697 | err = online_css(css); | |
4698 | if (err) | |
1fed1b2e | 4699 | goto err_list_del; |
94419627 | 4700 | |
c81c925a | 4701 | if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
d51f39b0 | 4702 | cgroup_parent(parent)) { |
ed3d261b | 4703 | 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 | 4704 | current->comm, current->pid, ss->name); |
c81c925a | 4705 | if (!strcmp(ss->name, "memory")) |
ed3d261b | 4706 | pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
c81c925a TH |
4707 | ss->warned_broken_hierarchy = true; |
4708 | } | |
4709 | ||
4710 | return 0; | |
4711 | ||
1fed1b2e TH |
4712 | err_list_del: |
4713 | list_del_rcu(&css->sibling); | |
32d01dc7 | 4714 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
15a4c835 TH |
4715 | err_free_id: |
4716 | cgroup_idr_remove(&ss->css_idr, css->id); | |
3eb59ec6 | 4717 | err_free_percpu_ref: |
9a1049da | 4718 | percpu_ref_exit(&css->refcnt); |
3eb59ec6 | 4719 | err_free_css: |
a2bed820 | 4720 | call_rcu(&css->rcu_head, css_free_rcu_fn); |
c81c925a TH |
4721 | return err; |
4722 | } | |
4723 | ||
b3bfd983 TH |
4724 | static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
4725 | umode_t mode) | |
ddbcc7e8 | 4726 | { |
a9746d8d TH |
4727 | struct cgroup *parent, *cgrp; |
4728 | struct cgroup_root *root; | |
ddbcc7e8 | 4729 | struct cgroup_subsys *ss; |
2bd59d48 | 4730 | struct kernfs_node *kn; |
a14c6874 | 4731 | struct cftype *base_files; |
b3bfd983 | 4732 | int ssid, ret; |
ddbcc7e8 | 4733 | |
71b1fb5c AC |
4734 | /* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable. |
4735 | */ | |
4736 | if (strchr(name, '\n')) | |
4737 | return -EINVAL; | |
4738 | ||
a9746d8d TH |
4739 | parent = cgroup_kn_lock_live(parent_kn); |
4740 | if (!parent) | |
4741 | return -ENODEV; | |
4742 | root = parent->root; | |
ddbcc7e8 | 4743 | |
0a950f65 | 4744 | /* allocate the cgroup and its ID, 0 is reserved for the root */ |
bd89aabc | 4745 | cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); |
ba0f4d76 TH |
4746 | if (!cgrp) { |
4747 | ret = -ENOMEM; | |
4748 | goto out_unlock; | |
0ab02ca8 LZ |
4749 | } |
4750 | ||
2aad2a86 | 4751 | ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
9d755d33 TH |
4752 | if (ret) |
4753 | goto out_free_cgrp; | |
4754 | ||
0ab02ca8 LZ |
4755 | /* |
4756 | * Temporarily set the pointer to NULL, so idr_find() won't return | |
4757 | * a half-baked cgroup. | |
4758 | */ | |
cf780b7d | 4759 | cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
0ab02ca8 | 4760 | if (cgrp->id < 0) { |
ba0f4d76 | 4761 | ret = -ENOMEM; |
9d755d33 | 4762 | goto out_cancel_ref; |
976c06bc TH |
4763 | } |
4764 | ||
cc31edce | 4765 | init_cgroup_housekeeping(cgrp); |
ddbcc7e8 | 4766 | |
9d800df1 | 4767 | cgrp->self.parent = &parent->self; |
ba0f4d76 | 4768 | cgrp->root = root; |
ddbcc7e8 | 4769 | |
b6abdb0e LZ |
4770 | if (notify_on_release(parent)) |
4771 | set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); | |
4772 | ||
2260e7fc TH |
4773 | if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
4774 | set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); | |
97978e6d | 4775 | |
2bd59d48 | 4776 | /* create the directory */ |
e61734c5 | 4777 | kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
2bd59d48 | 4778 | if (IS_ERR(kn)) { |
ba0f4d76 TH |
4779 | ret = PTR_ERR(kn); |
4780 | goto out_free_id; | |
2bd59d48 TH |
4781 | } |
4782 | cgrp->kn = kn; | |
ddbcc7e8 | 4783 | |
4e139afc | 4784 | /* |
6f30558f TH |
4785 | * This extra ref will be put in cgroup_free_fn() and guarantees |
4786 | * that @cgrp->kn is always accessible. | |
4e139afc | 4787 | */ |
6f30558f | 4788 | kernfs_get(kn); |
ddbcc7e8 | 4789 | |
0cb51d71 | 4790 | cgrp->self.serial_nr = css_serial_nr_next++; |
53fa5261 | 4791 | |
4e139afc | 4792 | /* allocation complete, commit to creation */ |
d5c419b6 | 4793 | list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
3c9c825b | 4794 | atomic_inc(&root->nr_cgrps); |
59f5296b | 4795 | cgroup_get(parent); |
415cf07a | 4796 | |
0d80255e TH |
4797 | /* |
4798 | * @cgrp is now fully operational. If something fails after this | |
4799 | * point, it'll be released via the normal destruction path. | |
4800 | */ | |
6fa4918d | 4801 | cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
4e96ee8e | 4802 | |
ba0f4d76 TH |
4803 | ret = cgroup_kn_set_ugid(kn); |
4804 | if (ret) | |
4805 | goto out_destroy; | |
49957f8e | 4806 | |
a14c6874 TH |
4807 | if (cgroup_on_dfl(cgrp)) |
4808 | base_files = cgroup_dfl_base_files; | |
4809 | else | |
4810 | base_files = cgroup_legacy_base_files; | |
4811 | ||
4812 | ret = cgroup_addrm_files(cgrp, base_files, true); | |
ba0f4d76 TH |
4813 | if (ret) |
4814 | goto out_destroy; | |
628f7cd4 | 4815 | |
9d403e99 | 4816 | /* let's create and online css's */ |
b85d2040 | 4817 | for_each_subsys(ss, ssid) { |
f392e51c | 4818 | if (parent->child_subsys_mask & (1 << ssid)) { |
f63070d3 TH |
4819 | ret = create_css(cgrp, ss, |
4820 | parent->subtree_control & (1 << ssid)); | |
ba0f4d76 TH |
4821 | if (ret) |
4822 | goto out_destroy; | |
b85d2040 | 4823 | } |
a8638030 | 4824 | } |
ddbcc7e8 | 4825 | |
bd53d617 TH |
4826 | /* |
4827 | * On the default hierarchy, a child doesn't automatically inherit | |
667c2491 | 4828 | * subtree_control from the parent. Each is configured manually. |
bd53d617 | 4829 | */ |
667c2491 TH |
4830 | if (!cgroup_on_dfl(cgrp)) { |
4831 | cgrp->subtree_control = parent->subtree_control; | |
4832 | cgroup_refresh_child_subsys_mask(cgrp); | |
4833 | } | |
2bd59d48 | 4834 | |
2bd59d48 | 4835 | kernfs_activate(kn); |
ddbcc7e8 | 4836 | |
ba0f4d76 TH |
4837 | ret = 0; |
4838 | goto out_unlock; | |
ddbcc7e8 | 4839 | |
ba0f4d76 | 4840 | out_free_id: |
6fa4918d | 4841 | cgroup_idr_remove(&root->cgroup_idr, cgrp->id); |
9d755d33 | 4842 | out_cancel_ref: |
9a1049da | 4843 | percpu_ref_exit(&cgrp->self.refcnt); |
ba0f4d76 | 4844 | out_free_cgrp: |
bd89aabc | 4845 | kfree(cgrp); |
ba0f4d76 | 4846 | out_unlock: |
a9746d8d | 4847 | cgroup_kn_unlock(parent_kn); |
ba0f4d76 | 4848 | return ret; |
4b8b47eb | 4849 | |
ba0f4d76 | 4850 | out_destroy: |
4b8b47eb | 4851 | cgroup_destroy_locked(cgrp); |
ba0f4d76 | 4852 | goto out_unlock; |
ddbcc7e8 PM |
4853 | } |
4854 | ||
223dbc38 TH |
4855 | /* |
4856 | * This is called when the refcnt of a css is confirmed to be killed. | |
249f3468 TH |
4857 | * css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
4858 | * initate destruction and put the css ref from kill_css(). | |
223dbc38 TH |
4859 | */ |
4860 | static void css_killed_work_fn(struct work_struct *work) | |
d3daf28d | 4861 | { |
223dbc38 TH |
4862 | struct cgroup_subsys_state *css = |
4863 | container_of(work, struct cgroup_subsys_state, destroy_work); | |
d3daf28d | 4864 | |
f20104de | 4865 | mutex_lock(&cgroup_mutex); |
09a503ea | 4866 | offline_css(css); |
f20104de | 4867 | mutex_unlock(&cgroup_mutex); |
09a503ea | 4868 | |
09a503ea | 4869 | css_put(css); |
d3daf28d TH |
4870 | } |
4871 | ||
223dbc38 TH |
4872 | /* css kill confirmation processing requires process context, bounce */ |
4873 | static void css_killed_ref_fn(struct percpu_ref *ref) | |
d3daf28d TH |
4874 | { |
4875 | struct cgroup_subsys_state *css = | |
4876 | container_of(ref, struct cgroup_subsys_state, refcnt); | |
4877 | ||
223dbc38 | 4878 | INIT_WORK(&css->destroy_work, css_killed_work_fn); |
e5fca243 | 4879 | queue_work(cgroup_destroy_wq, &css->destroy_work); |
d3daf28d TH |
4880 | } |
4881 | ||
f392e51c TH |
4882 | /** |
4883 | * kill_css - destroy a css | |
4884 | * @css: css to destroy | |
4885 | * | |
4886 | * This function initiates destruction of @css by removing cgroup interface | |
4887 | * files and putting its base reference. ->css_offline() will be invoked | |
ec903c0c TH |
4888 | * asynchronously once css_tryget_online() is guaranteed to fail and when |
4889 | * the reference count reaches zero, @css will be released. | |
f392e51c TH |
4890 | */ |
4891 | static void kill_css(struct cgroup_subsys_state *css) | |
edae0c33 | 4892 | { |
01f6474c | 4893 | lockdep_assert_held(&cgroup_mutex); |
94419627 | 4894 | |
2bd59d48 TH |
4895 | /* |
4896 | * This must happen before css is disassociated with its cgroup. | |
4897 | * See seq_css() for details. | |
4898 | */ | |
aec25020 | 4899 | cgroup_clear_dir(css->cgroup, 1 << css->ss->id); |
3c14f8b4 | 4900 | |
edae0c33 TH |
4901 | /* |
4902 | * Killing would put the base ref, but we need to keep it alive | |
4903 | * until after ->css_offline(). | |
4904 | */ | |
4905 | css_get(css); | |
4906 | ||
4907 | /* | |
4908 | * cgroup core guarantees that, by the time ->css_offline() is | |
4909 | * invoked, no new css reference will be given out via | |
ec903c0c | 4910 | * css_tryget_online(). We can't simply call percpu_ref_kill() and |
edae0c33 TH |
4911 | * proceed to offlining css's because percpu_ref_kill() doesn't |
4912 | * guarantee that the ref is seen as killed on all CPUs on return. | |
4913 | * | |
4914 | * Use percpu_ref_kill_and_confirm() to get notifications as each | |
4915 | * css is confirmed to be seen as killed on all CPUs. | |
4916 | */ | |
4917 | percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); | |
d3daf28d TH |
4918 | } |
4919 | ||
4920 | /** | |
4921 | * cgroup_destroy_locked - the first stage of cgroup destruction | |
4922 | * @cgrp: cgroup to be destroyed | |
4923 | * | |
4924 | * css's make use of percpu refcnts whose killing latency shouldn't be | |
4925 | * exposed to userland and are RCU protected. Also, cgroup core needs to | |
ec903c0c TH |
4926 | * guarantee that css_tryget_online() won't succeed by the time |
4927 | * ->css_offline() is invoked. To satisfy all the requirements, | |
4928 | * destruction is implemented in the following two steps. | |
d3daf28d TH |
4929 | * |
4930 | * s1. Verify @cgrp can be destroyed and mark it dying. Remove all | |
4931 | * userland visible parts and start killing the percpu refcnts of | |
4932 | * css's. Set up so that the next stage will be kicked off once all | |
4933 | * the percpu refcnts are confirmed to be killed. | |
4934 | * | |
4935 | * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the | |
4936 | * rest of destruction. Once all cgroup references are gone, the | |
4937 | * cgroup is RCU-freed. | |
4938 | * | |
4939 | * This function implements s1. After this step, @cgrp is gone as far as | |
4940 | * the userland is concerned and a new cgroup with the same name may be | |
4941 | * created. As cgroup doesn't care about the names internally, this | |
4942 | * doesn't cause any problem. | |
4943 | */ | |
42809dd4 TH |
4944 | static int cgroup_destroy_locked(struct cgroup *cgrp) |
4945 | __releases(&cgroup_mutex) __acquires(&cgroup_mutex) | |
ddbcc7e8 | 4946 | { |
2bd59d48 | 4947 | struct cgroup_subsys_state *css; |
ddd69148 | 4948 | bool empty; |
1c6727af | 4949 | int ssid; |
ddbcc7e8 | 4950 | |
42809dd4 TH |
4951 | lockdep_assert_held(&cgroup_mutex); |
4952 | ||
ddd69148 | 4953 | /* |
96d365e0 | 4954 | * css_set_rwsem synchronizes access to ->cset_links and prevents |
89c5509b | 4955 | * @cgrp from being removed while put_css_set() is in progress. |
ddd69148 | 4956 | */ |
96d365e0 | 4957 | down_read(&css_set_rwsem); |
bb78a92f | 4958 | empty = list_empty(&cgrp->cset_links); |
96d365e0 | 4959 | up_read(&css_set_rwsem); |
ddd69148 | 4960 | if (!empty) |
ddbcc7e8 | 4961 | return -EBUSY; |
a043e3b2 | 4962 | |
bb78a92f | 4963 | /* |
d5c419b6 TH |
4964 | * Make sure there's no live children. We can't test emptiness of |
4965 | * ->self.children as dead children linger on it while being | |
4966 | * drained; otherwise, "rmdir parent/child parent" may fail. | |
bb78a92f | 4967 | */ |
f3d46500 | 4968 | if (css_has_online_children(&cgrp->self)) |
bb78a92f HD |
4969 | return -EBUSY; |
4970 | ||
455050d2 TH |
4971 | /* |
4972 | * Mark @cgrp dead. This prevents further task migration and child | |
de3f0341 | 4973 | * creation by disabling cgroup_lock_live_group(). |
455050d2 | 4974 | */ |
184faf32 | 4975 | cgrp->self.flags &= ~CSS_ONLINE; |
ddbcc7e8 | 4976 | |
249f3468 | 4977 | /* initiate massacre of all css's */ |
1c6727af TH |
4978 | for_each_css(css, ssid, cgrp) |
4979 | kill_css(css); | |
455050d2 | 4980 | |
455050d2 | 4981 | /* |
01f6474c TH |
4982 | * Remove @cgrp directory along with the base files. @cgrp has an |
4983 | * extra ref on its kn. | |
f20104de | 4984 | */ |
01f6474c | 4985 | kernfs_remove(cgrp->kn); |
f20104de | 4986 | |
d51f39b0 | 4987 | check_for_release(cgroup_parent(cgrp)); |
2bd59d48 | 4988 | |
249f3468 | 4989 | /* put the base reference */ |
9d755d33 | 4990 | percpu_ref_kill(&cgrp->self.refcnt); |
455050d2 | 4991 | |
ea15f8cc TH |
4992 | return 0; |
4993 | }; | |
4994 | ||
2bd59d48 | 4995 | static int cgroup_rmdir(struct kernfs_node *kn) |
42809dd4 | 4996 | { |
a9746d8d | 4997 | struct cgroup *cgrp; |
2bd59d48 | 4998 | int ret = 0; |
42809dd4 | 4999 | |
a9746d8d TH |
5000 | cgrp = cgroup_kn_lock_live(kn); |
5001 | if (!cgrp) | |
5002 | return 0; | |
42809dd4 | 5003 | |
a9746d8d | 5004 | ret = cgroup_destroy_locked(cgrp); |
2bb566cb | 5005 | |
a9746d8d | 5006 | cgroup_kn_unlock(kn); |
42809dd4 | 5007 | return ret; |
8e3f6541 TH |
5008 | } |
5009 | ||
2bd59d48 TH |
5010 | static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
5011 | .remount_fs = cgroup_remount, | |
5012 | .show_options = cgroup_show_options, | |
5013 | .mkdir = cgroup_mkdir, | |
5014 | .rmdir = cgroup_rmdir, | |
5015 | .rename = cgroup_rename, | |
5016 | }; | |
5017 | ||
15a4c835 | 5018 | static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
ddbcc7e8 | 5019 | { |
ddbcc7e8 | 5020 | struct cgroup_subsys_state *css; |
cfe36bde DC |
5021 | |
5022 | printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); | |
ddbcc7e8 | 5023 | |
648bb56d TH |
5024 | mutex_lock(&cgroup_mutex); |
5025 | ||
15a4c835 | 5026 | idr_init(&ss->css_idr); |
0adb0704 | 5027 | INIT_LIST_HEAD(&ss->cfts); |
8e3f6541 | 5028 | |
3dd06ffa TH |
5029 | /* Create the root cgroup state for this subsystem */ |
5030 | ss->root = &cgrp_dfl_root; | |
5031 | css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss)); | |
ddbcc7e8 PM |
5032 | /* We don't handle early failures gracefully */ |
5033 | BUG_ON(IS_ERR(css)); | |
ddfcadab | 5034 | init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
3b514d24 TH |
5035 | |
5036 | /* | |
5037 | * Root csses are never destroyed and we can't initialize | |
5038 | * percpu_ref during early init. Disable refcnting. | |
5039 | */ | |
5040 | css->flags |= CSS_NO_REF; | |
5041 | ||
15a4c835 | 5042 | if (early) { |
9395a450 | 5043 | /* allocation can't be done safely during early init */ |
15a4c835 TH |
5044 | css->id = 1; |
5045 | } else { | |
5046 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); | |
5047 | BUG_ON(css->id < 0); | |
5048 | } | |
ddbcc7e8 | 5049 | |
e8d55fde | 5050 | /* Update the init_css_set to contain a subsys |
817929ec | 5051 | * pointer to this state - since the subsystem is |
e8d55fde | 5052 | * newly registered, all tasks and hence the |
3dd06ffa | 5053 | * init_css_set is in the subsystem's root cgroup. */ |
aec25020 | 5054 | init_css_set.subsys[ss->id] = css; |
ddbcc7e8 | 5055 | |
cb4a3167 AS |
5056 | have_fork_callback |= (bool)ss->fork << ss->id; |
5057 | have_exit_callback |= (bool)ss->exit << ss->id; | |
7e47682e | 5058 | have_canfork_callback |= (bool)ss->can_fork << ss->id; |
ddbcc7e8 | 5059 | |
e8d55fde LZ |
5060 | /* At system boot, before all subsystems have been |
5061 | * registered, no tasks have been forked, so we don't | |
5062 | * need to invoke fork callbacks here. */ | |
5063 | BUG_ON(!list_empty(&init_task.tasks)); | |
5064 | ||
ae7f164a | 5065 | BUG_ON(online_css(css)); |
a8638030 | 5066 | |
cf5d5941 BB |
5067 | mutex_unlock(&cgroup_mutex); |
5068 | } | |
cf5d5941 | 5069 | |
ddbcc7e8 | 5070 | /** |
a043e3b2 LZ |
5071 | * cgroup_init_early - cgroup initialization at system boot |
5072 | * | |
5073 | * Initialize cgroups at system boot, and initialize any | |
5074 | * subsystems that request early init. | |
ddbcc7e8 PM |
5075 | */ |
5076 | int __init cgroup_init_early(void) | |
5077 | { | |
7b9a6ba5 | 5078 | static struct cgroup_sb_opts __initdata opts; |
30159ec7 | 5079 | struct cgroup_subsys *ss; |
ddbcc7e8 | 5080 | int i; |
30159ec7 | 5081 | |
3dd06ffa | 5082 | init_cgroup_root(&cgrp_dfl_root, &opts); |
3b514d24 TH |
5083 | cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
5084 | ||
a4ea1cc9 | 5085 | RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
817929ec | 5086 | |
3ed80a62 | 5087 | for_each_subsys(ss, i) { |
aec25020 | 5088 | WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
073219e9 TH |
5089 | "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p name:id=%d:%s\n", |
5090 | i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, | |
aec25020 | 5091 | ss->id, ss->name); |
073219e9 TH |
5092 | WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
5093 | "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); | |
5094 | ||
aec25020 | 5095 | ss->id = i; |
073219e9 | 5096 | ss->name = cgroup_subsys_name[i]; |
3e1d2eed TH |
5097 | if (!ss->legacy_name) |
5098 | ss->legacy_name = cgroup_subsys_name[i]; | |
ddbcc7e8 PM |
5099 | |
5100 | if (ss->early_init) | |
15a4c835 | 5101 | cgroup_init_subsys(ss, true); |
ddbcc7e8 PM |
5102 | } |
5103 | return 0; | |
5104 | } | |
5105 | ||
5106 | /** | |
a043e3b2 LZ |
5107 | * cgroup_init - cgroup initialization |
5108 | * | |
5109 | * Register cgroup filesystem and /proc file, and initialize | |
5110 | * any subsystems that didn't request early init. | |
ddbcc7e8 PM |
5111 | */ |
5112 | int __init cgroup_init(void) | |
5113 | { | |
30159ec7 | 5114 | struct cgroup_subsys *ss; |
0ac801fe | 5115 | unsigned long key; |
172a2c06 | 5116 | int ssid, err; |
ddbcc7e8 | 5117 | |
1ed13287 | 5118 | BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
a14c6874 TH |
5119 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
5120 | BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); | |
ddbcc7e8 | 5121 | |
54e7b4eb | 5122 | mutex_lock(&cgroup_mutex); |
54e7b4eb | 5123 | |
82fe9b0d TH |
5124 | /* Add init_css_set to the hash table */ |
5125 | key = css_set_hash(init_css_set.subsys); | |
5126 | hash_add(css_set_table, &init_css_set.hlist, key); | |
5127 | ||
3dd06ffa | 5128 | BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
4e96ee8e | 5129 | |
54e7b4eb TH |
5130 | mutex_unlock(&cgroup_mutex); |
5131 | ||
172a2c06 | 5132 | for_each_subsys(ss, ssid) { |
15a4c835 TH |
5133 | if (ss->early_init) { |
5134 | struct cgroup_subsys_state *css = | |
5135 | init_css_set.subsys[ss->id]; | |
5136 | ||
5137 | css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, | |
5138 | GFP_KERNEL); | |
5139 | BUG_ON(css->id < 0); | |
5140 | } else { | |
5141 | cgroup_init_subsys(ss, false); | |
5142 | } | |
172a2c06 | 5143 | |
2d8f243a TH |
5144 | list_add_tail(&init_css_set.e_cset_node[ssid], |
5145 | &cgrp_dfl_root.cgrp.e_csets[ssid]); | |
172a2c06 TH |
5146 | |
5147 | /* | |
c731ae1d LZ |
5148 | * Setting dfl_root subsys_mask needs to consider the |
5149 | * disabled flag and cftype registration needs kmalloc, | |
5150 | * both of which aren't available during early_init. | |
172a2c06 | 5151 | */ |
fc5ed1e9 | 5152 | if (!cgroup_ssid_enabled(ssid)) |
a8ddc821 TH |
5153 | continue; |
5154 | ||
5155 | cgrp_dfl_root.subsys_mask |= 1 << ss->id; | |
5156 | ||
5157 | if (cgroup_legacy_files_on_dfl && !ss->dfl_cftypes) | |
5158 | ss->dfl_cftypes = ss->legacy_cftypes; | |
5159 | ||
5de4fa13 TH |
5160 | if (!ss->dfl_cftypes) |
5161 | cgrp_dfl_root_inhibit_ss_mask |= 1 << ss->id; | |
5162 | ||
a8ddc821 TH |
5163 | if (ss->dfl_cftypes == ss->legacy_cftypes) { |
5164 | WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); | |
5165 | } else { | |
5166 | WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); | |
5167 | WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); | |
c731ae1d | 5168 | } |
295458e6 VD |
5169 | |
5170 | if (ss->bind) | |
5171 | ss->bind(init_css_set.subsys[ssid]); | |
676db4af GK |
5172 | } |
5173 | ||
f9bb4882 EB |
5174 | err = sysfs_create_mount_point(fs_kobj, "cgroup"); |
5175 | if (err) | |
5176 | return err; | |
676db4af | 5177 | |
ddbcc7e8 | 5178 | err = register_filesystem(&cgroup_fs_type); |
676db4af | 5179 | if (err < 0) { |
f9bb4882 | 5180 | sysfs_remove_mount_point(fs_kobj, "cgroup"); |
2bd59d48 | 5181 | return err; |
676db4af | 5182 | } |
ddbcc7e8 | 5183 | |
46ae220b | 5184 | proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); |
2bd59d48 | 5185 | return 0; |
ddbcc7e8 | 5186 | } |
b4f48b63 | 5187 | |
e5fca243 TH |
5188 | static int __init cgroup_wq_init(void) |
5189 | { | |
5190 | /* | |
5191 | * There isn't much point in executing destruction path in | |
5192 | * parallel. Good chunk is serialized with cgroup_mutex anyway. | |
1a11533f | 5193 | * Use 1 for @max_active. |
e5fca243 TH |
5194 | * |
5195 | * We would prefer to do this in cgroup_init() above, but that | |
5196 | * is called before init_workqueues(): so leave this until after. | |
5197 | */ | |
1a11533f | 5198 | cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
e5fca243 | 5199 | BUG_ON(!cgroup_destroy_wq); |
b1a21367 TH |
5200 | |
5201 | /* | |
5202 | * Used to destroy pidlists and separate to serve as flush domain. | |
5203 | * Cap @max_active to 1 too. | |
5204 | */ | |
5205 | cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", | |
5206 | 0, 1); | |
5207 | BUG_ON(!cgroup_pidlist_destroy_wq); | |
5208 | ||
e5fca243 TH |
5209 | return 0; |
5210 | } | |
5211 | core_initcall(cgroup_wq_init); | |
5212 | ||
a424316c PM |
5213 | /* |
5214 | * proc_cgroup_show() | |
5215 | * - Print task's cgroup paths into seq_file, one line for each hierarchy | |
5216 | * - Used for /proc/<pid>/cgroup. | |
a424316c | 5217 | */ |
006f4ac4 ZL |
5218 | int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
5219 | struct pid *pid, struct task_struct *tsk) | |
a424316c | 5220 | { |
e61734c5 | 5221 | char *buf, *path; |
a424316c | 5222 | int retval; |
3dd06ffa | 5223 | struct cgroup_root *root; |
a424316c PM |
5224 | |
5225 | retval = -ENOMEM; | |
e61734c5 | 5226 | buf = kmalloc(PATH_MAX, GFP_KERNEL); |
a424316c PM |
5227 | if (!buf) |
5228 | goto out; | |
5229 | ||
a424316c | 5230 | mutex_lock(&cgroup_mutex); |
96d365e0 | 5231 | down_read(&css_set_rwsem); |
a424316c | 5232 | |
985ed670 | 5233 | for_each_root(root) { |
a424316c | 5234 | struct cgroup_subsys *ss; |
bd89aabc | 5235 | struct cgroup *cgrp; |
b85d2040 | 5236 | int ssid, count = 0; |
a424316c | 5237 | |
a2dd4247 | 5238 | if (root == &cgrp_dfl_root && !cgrp_dfl_root_visible) |
985ed670 TH |
5239 | continue; |
5240 | ||
2c6ab6d2 | 5241 | seq_printf(m, "%d:", root->hierarchy_id); |
d98817d4 TH |
5242 | if (root != &cgrp_dfl_root) |
5243 | for_each_subsys(ss, ssid) | |
5244 | if (root->subsys_mask & (1 << ssid)) | |
5245 | seq_printf(m, "%s%s", count++ ? "," : "", | |
3e1d2eed | 5246 | ss->legacy_name); |
c6d57f33 PM |
5247 | if (strlen(root->name)) |
5248 | seq_printf(m, "%sname=%s", count ? "," : "", | |
5249 | root->name); | |
a424316c | 5250 | seq_putc(m, ':'); |
7717f7ba | 5251 | cgrp = task_cgroup_from_root(tsk, root); |
e61734c5 TH |
5252 | path = cgroup_path(cgrp, buf, PATH_MAX); |
5253 | if (!path) { | |
5254 | retval = -ENAMETOOLONG; | |
a424316c | 5255 | goto out_unlock; |
e61734c5 TH |
5256 | } |
5257 | seq_puts(m, path); | |
a424316c PM |
5258 | seq_putc(m, '\n'); |
5259 | } | |
5260 | ||
006f4ac4 | 5261 | retval = 0; |
a424316c | 5262 | out_unlock: |
96d365e0 | 5263 | up_read(&css_set_rwsem); |
a424316c | 5264 | mutex_unlock(&cgroup_mutex); |
a424316c PM |
5265 | kfree(buf); |
5266 | out: | |
5267 | return retval; | |
5268 | } | |
5269 | ||
a424316c PM |
5270 | /* Display information about each subsystem and each hierarchy */ |
5271 | static int proc_cgroupstats_show(struct seq_file *m, void *v) | |
5272 | { | |
30159ec7 | 5273 | struct cgroup_subsys *ss; |
a424316c | 5274 | int i; |
a424316c | 5275 | |
8bab8dde | 5276 | seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
aae8aab4 BB |
5277 | /* |
5278 | * ideally we don't want subsystems moving around while we do this. | |
5279 | * cgroup_mutex is also necessary to guarantee an atomic snapshot of | |
5280 | * subsys/hierarchy state. | |
5281 | */ | |
a424316c | 5282 | mutex_lock(&cgroup_mutex); |
30159ec7 TH |
5283 | |
5284 | for_each_subsys(ss, i) | |
2c6ab6d2 | 5285 | seq_printf(m, "%s\t%d\t%d\t%d\n", |
3e1d2eed | 5286 | ss->legacy_name, ss->root->hierarchy_id, |
fc5ed1e9 TH |
5287 | atomic_read(&ss->root->nr_cgrps), |
5288 | cgroup_ssid_enabled(i)); | |
30159ec7 | 5289 | |
a424316c PM |
5290 | mutex_unlock(&cgroup_mutex); |
5291 | return 0; | |
5292 | } | |
5293 | ||
5294 | static int cgroupstats_open(struct inode *inode, struct file *file) | |
5295 | { | |
9dce07f1 | 5296 | return single_open(file, proc_cgroupstats_show, NULL); |
a424316c PM |
5297 | } |
5298 | ||
828c0950 | 5299 | static const struct file_operations proc_cgroupstats_operations = { |
a424316c PM |
5300 | .open = cgroupstats_open, |
5301 | .read = seq_read, | |
5302 | .llseek = seq_lseek, | |
5303 | .release = single_release, | |
5304 | }; | |
5305 | ||
7e47682e AS |
5306 | static void **subsys_canfork_priv_p(void *ss_priv[CGROUP_CANFORK_COUNT], int i) |
5307 | { | |
5308 | if (CGROUP_CANFORK_START <= i && i < CGROUP_CANFORK_END) | |
5309 | return &ss_priv[i - CGROUP_CANFORK_START]; | |
5310 | return NULL; | |
5311 | } | |
5312 | ||
5313 | static void *subsys_canfork_priv(void *ss_priv[CGROUP_CANFORK_COUNT], int i) | |
5314 | { | |
5315 | void **private = subsys_canfork_priv_p(ss_priv, i); | |
5316 | return private ? *private : NULL; | |
5317 | } | |
5318 | ||
b4f48b63 | 5319 | /** |
eaf797ab | 5320 | * cgroup_fork - initialize cgroup related fields during copy_process() |
a043e3b2 | 5321 | * @child: pointer to task_struct of forking parent process. |
b4f48b63 | 5322 | * |
eaf797ab TH |
5323 | * A task is associated with the init_css_set until cgroup_post_fork() |
5324 | * attaches it to the parent's css_set. Empty cg_list indicates that | |
5325 | * @child isn't holding reference to its css_set. | |
b4f48b63 PM |
5326 | */ |
5327 | void cgroup_fork(struct task_struct *child) | |
5328 | { | |
eaf797ab | 5329 | RCU_INIT_POINTER(child->cgroups, &init_css_set); |
817929ec | 5330 | INIT_LIST_HEAD(&child->cg_list); |
b4f48b63 PM |
5331 | } |
5332 | ||
7e47682e AS |
5333 | /** |
5334 | * cgroup_can_fork - called on a new task before the process is exposed | |
5335 | * @child: the task in question. | |
5336 | * | |
5337 | * This calls the subsystem can_fork() callbacks. If the can_fork() callback | |
5338 | * returns an error, the fork aborts with that error code. This allows for | |
5339 | * a cgroup subsystem to conditionally allow or deny new forks. | |
5340 | */ | |
5341 | int cgroup_can_fork(struct task_struct *child, | |
5342 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5343 | { | |
5344 | struct cgroup_subsys *ss; | |
5345 | int i, j, ret; | |
5346 | ||
5347 | for_each_subsys_which(ss, i, &have_canfork_callback) { | |
5348 | ret = ss->can_fork(child, subsys_canfork_priv_p(ss_priv, i)); | |
5349 | if (ret) | |
5350 | goto out_revert; | |
5351 | } | |
5352 | ||
5353 | return 0; | |
5354 | ||
5355 | out_revert: | |
5356 | for_each_subsys(ss, j) { | |
5357 | if (j >= i) | |
5358 | break; | |
5359 | if (ss->cancel_fork) | |
5360 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, j)); | |
5361 | } | |
5362 | ||
5363 | return ret; | |
5364 | } | |
5365 | ||
5366 | /** | |
5367 | * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() | |
5368 | * @child: the task in question | |
5369 | * | |
5370 | * This calls the cancel_fork() callbacks if a fork failed *after* | |
5371 | * cgroup_can_fork() succeded. | |
5372 | */ | |
5373 | void cgroup_cancel_fork(struct task_struct *child, | |
5374 | void *ss_priv[CGROUP_CANFORK_COUNT]) | |
5375 | { | |
5376 | struct cgroup_subsys *ss; | |
5377 | int i; | |
5378 | ||
5379 | for_each_subsys(ss, i) | |
5380 | if (ss->cancel_fork) | |
5381 | ss->cancel_fork(child, subsys_canfork_priv(ss_priv, i)); | |
5382 | } | |
5383 | ||
817929ec | 5384 | /** |
a043e3b2 LZ |
5385 | * cgroup_post_fork - called on a new task after adding it to the task list |
5386 | * @child: the task in question | |
5387 | * | |
5edee61e TH |
5388 | * Adds the task to the list running through its css_set if necessary and |
5389 | * call the subsystem fork() callbacks. Has to be after the task is | |
5390 | * visible on the task list in case we race with the first call to | |
0942eeee | 5391 | * cgroup_task_iter_start() - to guarantee that the new task ends up on its |
5edee61e | 5392 | * list. |
a043e3b2 | 5393 | */ |
7e47682e AS |
5394 | void cgroup_post_fork(struct task_struct *child, |
5395 | void *old_ss_priv[CGROUP_CANFORK_COUNT]) | |
817929ec | 5396 | { |
30159ec7 | 5397 | struct cgroup_subsys *ss; |
5edee61e TH |
5398 | int i; |
5399 | ||
3ce3230a | 5400 | /* |
251f8c03 | 5401 | * This may race against cgroup_enable_task_cg_lists(). As that |
eaf797ab TH |
5402 | * function sets use_task_css_set_links before grabbing |
5403 | * tasklist_lock and we just went through tasklist_lock to add | |
5404 | * @child, it's guaranteed that either we see the set | |
5405 | * use_task_css_set_links or cgroup_enable_task_cg_lists() sees | |
5406 | * @child during its iteration. | |
5407 | * | |
5408 | * If we won the race, @child is associated with %current's | |
5409 | * css_set. Grabbing css_set_rwsem guarantees both that the | |
5410 | * association is stable, and, on completion of the parent's | |
5411 | * migration, @child is visible in the source of migration or | |
5412 | * already in the destination cgroup. This guarantee is necessary | |
5413 | * when implementing operations which need to migrate all tasks of | |
5414 | * a cgroup to another. | |
5415 | * | |
251f8c03 | 5416 | * Note that if we lose to cgroup_enable_task_cg_lists(), @child |
eaf797ab TH |
5417 | * will remain in init_css_set. This is safe because all tasks are |
5418 | * in the init_css_set before cg_links is enabled and there's no | |
5419 | * operation which transfers all tasks out of init_css_set. | |
3ce3230a | 5420 | */ |
817929ec | 5421 | if (use_task_css_set_links) { |
eaf797ab TH |
5422 | struct css_set *cset; |
5423 | ||
96d365e0 | 5424 | down_write(&css_set_rwsem); |
0e1d768f | 5425 | cset = task_css_set(current); |
eaf797ab TH |
5426 | if (list_empty(&child->cg_list)) { |
5427 | rcu_assign_pointer(child->cgroups, cset); | |
5428 | list_add(&child->cg_list, &cset->tasks); | |
5429 | get_css_set(cset); | |
5430 | } | |
96d365e0 | 5431 | up_write(&css_set_rwsem); |
817929ec | 5432 | } |
5edee61e TH |
5433 | |
5434 | /* | |
5435 | * Call ss->fork(). This must happen after @child is linked on | |
5436 | * css_set; otherwise, @child might change state between ->fork() | |
5437 | * and addition to css_set. | |
5438 | */ | |
cb4a3167 | 5439 | for_each_subsys_which(ss, i, &have_fork_callback) |
7e47682e | 5440 | ss->fork(child, subsys_canfork_priv(old_ss_priv, i)); |
817929ec | 5441 | } |
5edee61e | 5442 | |
b4f48b63 PM |
5443 | /** |
5444 | * cgroup_exit - detach cgroup from exiting task | |
5445 | * @tsk: pointer to task_struct of exiting process | |
5446 | * | |
5447 | * Description: Detach cgroup from @tsk and release it. | |
5448 | * | |
5449 | * Note that cgroups marked notify_on_release force every task in | |
5450 | * them to take the global cgroup_mutex mutex when exiting. | |
5451 | * This could impact scaling on very large systems. Be reluctant to | |
5452 | * use notify_on_release cgroups where very high task exit scaling | |
5453 | * is required on large systems. | |
5454 | * | |
0e1d768f TH |
5455 | * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
5456 | * call cgroup_exit() while the task is still competent to handle | |
5457 | * notify_on_release(), then leave the task attached to the root cgroup in | |
5458 | * each hierarchy for the remainder of its exit. No need to bother with | |
5459 | * init_css_set refcnting. init_css_set never goes away and we can't race | |
e8604cb4 | 5460 | * with migration path - PF_EXITING is visible to migration path. |
b4f48b63 | 5461 | */ |
1ec41830 | 5462 | void cgroup_exit(struct task_struct *tsk) |
b4f48b63 | 5463 | { |
30159ec7 | 5464 | struct cgroup_subsys *ss; |
5abb8855 | 5465 | struct css_set *cset; |
eaf797ab | 5466 | bool put_cset = false; |
d41d5a01 | 5467 | int i; |
817929ec PM |
5468 | |
5469 | /* | |
0e1d768f TH |
5470 | * Unlink from @tsk from its css_set. As migration path can't race |
5471 | * with us, we can check cg_list without grabbing css_set_rwsem. | |
817929ec PM |
5472 | */ |
5473 | if (!list_empty(&tsk->cg_list)) { | |
96d365e0 | 5474 | down_write(&css_set_rwsem); |
0e1d768f | 5475 | list_del_init(&tsk->cg_list); |
96d365e0 | 5476 | up_write(&css_set_rwsem); |
0e1d768f | 5477 | put_cset = true; |
817929ec PM |
5478 | } |
5479 | ||
b4f48b63 | 5480 | /* Reassign the task to the init_css_set. */ |
a8ad805c TH |
5481 | cset = task_css_set(tsk); |
5482 | RCU_INIT_POINTER(tsk->cgroups, &init_css_set); | |
d41d5a01 | 5483 | |
cb4a3167 AS |
5484 | /* see cgroup_post_fork() for details */ |
5485 | for_each_subsys_which(ss, i, &have_exit_callback) { | |
5486 | struct cgroup_subsys_state *old_css = cset->subsys[i]; | |
5487 | struct cgroup_subsys_state *css = task_css(tsk, i); | |
30159ec7 | 5488 | |
cb4a3167 | 5489 | ss->exit(css, old_css, tsk); |
d41d5a01 | 5490 | } |
d41d5a01 | 5491 | |
eaf797ab | 5492 | if (put_cset) |
a25eb52e | 5493 | put_css_set(cset); |
b4f48b63 | 5494 | } |
697f4161 | 5495 | |
bd89aabc | 5496 | static void check_for_release(struct cgroup *cgrp) |
81a6a5cd | 5497 | { |
a25eb52e | 5498 | if (notify_on_release(cgrp) && !cgroup_has_tasks(cgrp) && |
971ff493 ZL |
5499 | !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
5500 | schedule_work(&cgrp->release_agent_work); | |
81a6a5cd PM |
5501 | } |
5502 | ||
81a6a5cd PM |
5503 | /* |
5504 | * Notify userspace when a cgroup is released, by running the | |
5505 | * configured release agent with the name of the cgroup (path | |
5506 | * relative to the root of cgroup file system) as the argument. | |
5507 | * | |
5508 | * Most likely, this user command will try to rmdir this cgroup. | |
5509 | * | |
5510 | * This races with the possibility that some other task will be | |
5511 | * attached to this cgroup before it is removed, or that some other | |
5512 | * user task will 'mkdir' a child cgroup of this cgroup. That's ok. | |
5513 | * The presumed 'rmdir' will fail quietly if this cgroup is no longer | |
5514 | * unused, and this cgroup will be reprieved from its death sentence, | |
5515 | * to continue to serve a useful existence. Next time it's released, | |
5516 | * we will get notified again, if it still has 'notify_on_release' set. | |
5517 | * | |
5518 | * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which | |
5519 | * means only wait until the task is successfully execve()'d. The | |
5520 | * separate release agent task is forked by call_usermodehelper(), | |
5521 | * then control in this thread returns here, without waiting for the | |
5522 | * release agent task. We don't bother to wait because the caller of | |
5523 | * this routine has no use for the exit status of the release agent | |
5524 | * task, so no sense holding our caller up for that. | |
81a6a5cd | 5525 | */ |
81a6a5cd PM |
5526 | static void cgroup_release_agent(struct work_struct *work) |
5527 | { | |
971ff493 ZL |
5528 | struct cgroup *cgrp = |
5529 | container_of(work, struct cgroup, release_agent_work); | |
5530 | char *pathbuf = NULL, *agentbuf = NULL, *path; | |
5531 | char *argv[3], *envp[3]; | |
5532 | ||
81a6a5cd | 5533 | mutex_lock(&cgroup_mutex); |
971ff493 ZL |
5534 | |
5535 | pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); | |
5536 | agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); | |
5537 | if (!pathbuf || !agentbuf) | |
5538 | goto out; | |
5539 | ||
5540 | path = cgroup_path(cgrp, pathbuf, PATH_MAX); | |
5541 | if (!path) | |
5542 | goto out; | |
5543 | ||
5544 | argv[0] = agentbuf; | |
5545 | argv[1] = path; | |
5546 | argv[2] = NULL; | |
5547 | ||
5548 | /* minimal command environment */ | |
5549 | envp[0] = "HOME=/"; | |
5550 | envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; | |
5551 | envp[2] = NULL; | |
5552 | ||
81a6a5cd | 5553 | mutex_unlock(&cgroup_mutex); |
971ff493 | 5554 | call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
3e2cd91a | 5555 | goto out_free; |
971ff493 | 5556 | out: |
81a6a5cd | 5557 | mutex_unlock(&cgroup_mutex); |
3e2cd91a | 5558 | out_free: |
971ff493 ZL |
5559 | kfree(agentbuf); |
5560 | kfree(pathbuf); | |
81a6a5cd | 5561 | } |
8bab8dde PM |
5562 | |
5563 | static int __init cgroup_disable(char *str) | |
5564 | { | |
30159ec7 | 5565 | struct cgroup_subsys *ss; |
8bab8dde | 5566 | char *token; |
30159ec7 | 5567 | int i; |
8bab8dde PM |
5568 | |
5569 | while ((token = strsep(&str, ",")) != NULL) { | |
5570 | if (!*token) | |
5571 | continue; | |
be45c900 | 5572 | |
3ed80a62 | 5573 | for_each_subsys(ss, i) { |
3e1d2eed TH |
5574 | if (strcmp(token, ss->name) && |
5575 | strcmp(token, ss->legacy_name)) | |
5576 | continue; | |
5577 | ||
49d1dc4b | 5578 | static_branch_disable(cgroup_subsys_enabled_key[i]); |
3e1d2eed TH |
5579 | printk(KERN_INFO "Disabling %s control group subsystem\n", |
5580 | ss->name); | |
5581 | break; | |
8bab8dde PM |
5582 | } |
5583 | } | |
5584 | return 1; | |
5585 | } | |
5586 | __setup("cgroup_disable=", cgroup_disable); | |
38460b48 | 5587 | |
a8ddc821 TH |
5588 | static int __init cgroup_set_legacy_files_on_dfl(char *str) |
5589 | { | |
5590 | printk("cgroup: using legacy files on the default hierarchy\n"); | |
5591 | cgroup_legacy_files_on_dfl = true; | |
5592 | return 0; | |
5593 | } | |
5594 | __setup("cgroup__DEVEL__legacy_files_on_dfl", cgroup_set_legacy_files_on_dfl); | |
5595 | ||
b77d7b60 | 5596 | /** |
ec903c0c | 5597 | * css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
35cf0836 TH |
5598 | * @dentry: directory dentry of interest |
5599 | * @ss: subsystem of interest | |
b77d7b60 | 5600 | * |
5a17f543 TH |
5601 | * If @dentry is a directory for a cgroup which has @ss enabled on it, try |
5602 | * to get the corresponding css and return it. If such css doesn't exist | |
5603 | * or can't be pinned, an ERR_PTR value is returned. | |
e5d1367f | 5604 | */ |
ec903c0c TH |
5605 | struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
5606 | struct cgroup_subsys *ss) | |
e5d1367f | 5607 | { |
2bd59d48 TH |
5608 | struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
5609 | struct cgroup_subsys_state *css = NULL; | |
e5d1367f | 5610 | struct cgroup *cgrp; |
e5d1367f | 5611 | |
35cf0836 | 5612 | /* is @dentry a cgroup dir? */ |
2bd59d48 TH |
5613 | if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
5614 | kernfs_type(kn) != KERNFS_DIR) | |
e5d1367f SE |
5615 | return ERR_PTR(-EBADF); |
5616 | ||
5a17f543 TH |
5617 | rcu_read_lock(); |
5618 | ||
2bd59d48 TH |
5619 | /* |
5620 | * This path doesn't originate from kernfs and @kn could already | |
5621 | * have been or be removed at any point. @kn->priv is RCU | |
a4189487 | 5622 | * protected for this access. See css_release_work_fn() for details. |
2bd59d48 TH |
5623 | */ |
5624 | cgrp = rcu_dereference(kn->priv); | |
5625 | if (cgrp) | |
5626 | css = cgroup_css(cgrp, ss); | |
5a17f543 | 5627 | |
ec903c0c | 5628 | if (!css || !css_tryget_online(css)) |
5a17f543 TH |
5629 | css = ERR_PTR(-ENOENT); |
5630 | ||
5631 | rcu_read_unlock(); | |
5632 | return css; | |
e5d1367f | 5633 | } |
e5d1367f | 5634 | |
1cb650b9 LZ |
5635 | /** |
5636 | * css_from_id - lookup css by id | |
5637 | * @id: the cgroup id | |
5638 | * @ss: cgroup subsys to be looked into | |
5639 | * | |
5640 | * Returns the css if there's valid one with @id, otherwise returns NULL. | |
5641 | * Should be called under rcu_read_lock(). | |
5642 | */ | |
5643 | struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) | |
5644 | { | |
6fa4918d | 5645 | WARN_ON_ONCE(!rcu_read_lock_held()); |
adbe427b | 5646 | return id > 0 ? idr_find(&ss->css_idr, id) : NULL; |
e5d1367f SE |
5647 | } |
5648 | ||
fe693435 | 5649 | #ifdef CONFIG_CGROUP_DEBUG |
eb95419b TH |
5650 | static struct cgroup_subsys_state * |
5651 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
fe693435 PM |
5652 | { |
5653 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
5654 | ||
5655 | if (!css) | |
5656 | return ERR_PTR(-ENOMEM); | |
5657 | ||
5658 | return css; | |
5659 | } | |
5660 | ||
eb95419b | 5661 | static void debug_css_free(struct cgroup_subsys_state *css) |
fe693435 | 5662 | { |
eb95419b | 5663 | kfree(css); |
fe693435 PM |
5664 | } |
5665 | ||
182446d0 TH |
5666 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
5667 | struct cftype *cft) | |
fe693435 | 5668 | { |
182446d0 | 5669 | return cgroup_task_count(css->cgroup); |
fe693435 PM |
5670 | } |
5671 | ||
182446d0 TH |
5672 | static u64 current_css_set_read(struct cgroup_subsys_state *css, |
5673 | struct cftype *cft) | |
fe693435 PM |
5674 | { |
5675 | return (u64)(unsigned long)current->cgroups; | |
5676 | } | |
5677 | ||
182446d0 | 5678 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
03c78cbe | 5679 | struct cftype *cft) |
fe693435 PM |
5680 | { |
5681 | u64 count; | |
5682 | ||
5683 | rcu_read_lock(); | |
a8ad805c | 5684 | count = atomic_read(&task_css_set(current)->refcount); |
fe693435 PM |
5685 | rcu_read_unlock(); |
5686 | return count; | |
5687 | } | |
5688 | ||
2da8ca82 | 5689 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5690 | { |
69d0206c | 5691 | struct cgrp_cset_link *link; |
5abb8855 | 5692 | struct css_set *cset; |
e61734c5 TH |
5693 | char *name_buf; |
5694 | ||
5695 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
5696 | if (!name_buf) | |
5697 | return -ENOMEM; | |
7717f7ba | 5698 | |
96d365e0 | 5699 | down_read(&css_set_rwsem); |
7717f7ba | 5700 | rcu_read_lock(); |
5abb8855 | 5701 | cset = rcu_dereference(current->cgroups); |
69d0206c | 5702 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
7717f7ba | 5703 | struct cgroup *c = link->cgrp; |
7717f7ba | 5704 | |
a2dd4247 | 5705 | cgroup_name(c, name_buf, NAME_MAX + 1); |
2c6ab6d2 | 5706 | seq_printf(seq, "Root %d group %s\n", |
a2dd4247 | 5707 | c->root->hierarchy_id, name_buf); |
7717f7ba PM |
5708 | } |
5709 | rcu_read_unlock(); | |
96d365e0 | 5710 | up_read(&css_set_rwsem); |
e61734c5 | 5711 | kfree(name_buf); |
7717f7ba PM |
5712 | return 0; |
5713 | } | |
5714 | ||
5715 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
2da8ca82 | 5716 | static int cgroup_css_links_read(struct seq_file *seq, void *v) |
7717f7ba | 5717 | { |
2da8ca82 | 5718 | struct cgroup_subsys_state *css = seq_css(seq); |
69d0206c | 5719 | struct cgrp_cset_link *link; |
7717f7ba | 5720 | |
96d365e0 | 5721 | down_read(&css_set_rwsem); |
182446d0 | 5722 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
69d0206c | 5723 | struct css_set *cset = link->cset; |
7717f7ba PM |
5724 | struct task_struct *task; |
5725 | int count = 0; | |
c7561128 | 5726 | |
5abb8855 | 5727 | seq_printf(seq, "css_set %p\n", cset); |
c7561128 | 5728 | |
5abb8855 | 5729 | list_for_each_entry(task, &cset->tasks, cg_list) { |
c7561128 TH |
5730 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
5731 | goto overflow; | |
5732 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
5733 | } | |
5734 | ||
5735 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
5736 | if (count++ > MAX_TASKS_SHOWN_PER_CSS) | |
5737 | goto overflow; | |
5738 | seq_printf(seq, " task %d\n", task_pid_vnr(task)); | |
7717f7ba | 5739 | } |
c7561128 TH |
5740 | continue; |
5741 | overflow: | |
5742 | seq_puts(seq, " ...\n"); | |
7717f7ba | 5743 | } |
96d365e0 | 5744 | up_read(&css_set_rwsem); |
7717f7ba PM |
5745 | return 0; |
5746 | } | |
5747 | ||
182446d0 | 5748 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
fe693435 | 5749 | { |
a25eb52e ZL |
5750 | return (!cgroup_has_tasks(css->cgroup) && |
5751 | !css_has_online_children(&css->cgroup->self)); | |
fe693435 PM |
5752 | } |
5753 | ||
5754 | static struct cftype debug_files[] = { | |
fe693435 PM |
5755 | { |
5756 | .name = "taskcount", | |
5757 | .read_u64 = debug_taskcount_read, | |
5758 | }, | |
5759 | ||
5760 | { | |
5761 | .name = "current_css_set", | |
5762 | .read_u64 = current_css_set_read, | |
5763 | }, | |
5764 | ||
5765 | { | |
5766 | .name = "current_css_set_refcount", | |
5767 | .read_u64 = current_css_set_refcount_read, | |
5768 | }, | |
5769 | ||
7717f7ba PM |
5770 | { |
5771 | .name = "current_css_set_cg_links", | |
2da8ca82 | 5772 | .seq_show = current_css_set_cg_links_read, |
7717f7ba PM |
5773 | }, |
5774 | ||
5775 | { | |
5776 | .name = "cgroup_css_links", | |
2da8ca82 | 5777 | .seq_show = cgroup_css_links_read, |
7717f7ba PM |
5778 | }, |
5779 | ||
fe693435 PM |
5780 | { |
5781 | .name = "releasable", | |
5782 | .read_u64 = releasable_read, | |
5783 | }, | |
fe693435 | 5784 | |
4baf6e33 TH |
5785 | { } /* terminate */ |
5786 | }; | |
fe693435 | 5787 | |
073219e9 | 5788 | struct cgroup_subsys debug_cgrp_subsys = { |
92fb9748 TH |
5789 | .css_alloc = debug_css_alloc, |
5790 | .css_free = debug_css_free, | |
5577964e | 5791 | .legacy_cftypes = debug_files, |
fe693435 PM |
5792 | }; |
5793 | #endif /* CONFIG_CGROUP_DEBUG */ |