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1 #ifndef _LINUX_CGROUP_H
2 #define _LINUX_CGROUP_H
3 /*
4  *  cgroup interface
5  *
6  *  Copyright (C) 2003 BULL SA
7  *  Copyright (C) 2004-2006 Silicon Graphics, Inc.
8  *
9  */
10 
11 #include <linux/sched.h>
12 #include <linux/cpumask.h>
13 #include <linux/nodemask.h>
14 #include <linux/rculist.h>
15 #include <linux/cgroupstats.h>
16 #include <linux/fs.h>
17 #include <linux/seq_file.h>
18 #include <linux/kernfs.h>
19 #include <linux/jump_label.h>
20 #include <linux/nsproxy.h>
21 #include <linux/types.h>
22 #include <linux/ns_common.h>
23 #include <linux/nsproxy.h>
24 #include <linux/user_namespace.h>
25 
26 #include <linux/cgroup-defs.h>
27 
28 #ifdef CONFIG_CGROUPS
29 
30 /*
31  * All weight knobs on the default hierarhcy should use the following min,
32  * default and max values.  The default value is the logarithmic center of
33  * MIN and MAX and allows 100x to be expressed in both directions.
34  */
35 #define CGROUP_WEIGHT_MIN		1
36 #define CGROUP_WEIGHT_DFL		100
37 #define CGROUP_WEIGHT_MAX		10000
38 
39 /* a css_task_iter should be treated as an opaque object */
40 struct css_task_iter {
41 	struct cgroup_subsys		*ss;
42 
43 	struct list_head		*cset_pos;
44 	struct list_head		*cset_head;
45 
46 	struct list_head		*task_pos;
47 	struct list_head		*tasks_head;
48 	struct list_head		*mg_tasks_head;
49 
50 	struct css_set			*cur_cset;
51 	struct task_struct		*cur_task;
52 	struct list_head		iters_node;	/* css_set->task_iters */
53 };
54 
55 extern struct cgroup_root cgrp_dfl_root;
56 extern struct css_set init_css_set;
57 
58 #define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
59 #include <linux/cgroup_subsys.h>
60 #undef SUBSYS
61 
62 #define SUBSYS(_x)								\
63 	extern struct static_key_true _x ## _cgrp_subsys_enabled_key;		\
64 	extern struct static_key_true _x ## _cgrp_subsys_on_dfl_key;
65 #include <linux/cgroup_subsys.h>
66 #undef SUBSYS
67 
68 /**
69  * cgroup_subsys_enabled - fast test on whether a subsys is enabled
70  * @ss: subsystem in question
71  */
72 #define cgroup_subsys_enabled(ss)						\
73 	static_branch_likely(&ss ## _enabled_key)
74 
75 /**
76  * cgroup_subsys_on_dfl - fast test on whether a subsys is on default hierarchy
77  * @ss: subsystem in question
78  */
79 #define cgroup_subsys_on_dfl(ss)						\
80 	static_branch_likely(&ss ## _on_dfl_key)
81 
82 bool css_has_online_children(struct cgroup_subsys_state *css);
83 struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss);
84 struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup,
85 					     struct cgroup_subsys *ss);
86 struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
87 						       struct cgroup_subsys *ss);
88 
89 struct cgroup *cgroup_get_from_path(const char *path);
90 struct cgroup *cgroup_get_from_fd(int fd);
91 
92 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
93 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
94 
95 int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
96 int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
97 int cgroup_rm_cftypes(struct cftype *cfts);
98 void cgroup_file_notify(struct cgroup_file *cfile);
99 
100 int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
101 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
102 int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
103 		     struct pid *pid, struct task_struct *tsk);
104 
105 void cgroup_fork(struct task_struct *p);
106 extern int cgroup_can_fork(struct task_struct *p);
107 extern void cgroup_cancel_fork(struct task_struct *p);
108 extern void cgroup_post_fork(struct task_struct *p);
109 void cgroup_exit(struct task_struct *p);
110 void cgroup_free(struct task_struct *p);
111 
112 int cgroup_init_early(void);
113 int cgroup_init(void);
114 
115 /*
116  * Iteration helpers and macros.
117  */
118 
119 struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
120 					   struct cgroup_subsys_state *parent);
121 struct cgroup_subsys_state *css_next_descendant_pre(struct cgroup_subsys_state *pos,
122 						    struct cgroup_subsys_state *css);
123 struct cgroup_subsys_state *css_rightmost_descendant(struct cgroup_subsys_state *pos);
124 struct cgroup_subsys_state *css_next_descendant_post(struct cgroup_subsys_state *pos,
125 						     struct cgroup_subsys_state *css);
126 
127 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
128 					 struct cgroup_subsys_state **dst_cssp);
129 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
130 					struct cgroup_subsys_state **dst_cssp);
131 
132 void css_task_iter_start(struct cgroup_subsys_state *css,
133 			 struct css_task_iter *it);
134 struct task_struct *css_task_iter_next(struct css_task_iter *it);
135 void css_task_iter_end(struct css_task_iter *it);
136 
137 /**
138  * css_for_each_child - iterate through children of a css
139  * @pos: the css * to use as the loop cursor
140  * @parent: css whose children to walk
141  *
142  * Walk @parent's children.  Must be called under rcu_read_lock().
143  *
144  * If a subsystem synchronizes ->css_online() and the start of iteration, a
145  * css which finished ->css_online() is guaranteed to be visible in the
146  * future iterations and will stay visible until the last reference is put.
147  * A css which hasn't finished ->css_online() or already finished
148  * ->css_offline() may show up during traversal.  It's each subsystem's
149  * responsibility to synchronize against on/offlining.
150  *
151  * It is allowed to temporarily drop RCU read lock during iteration.  The
152  * caller is responsible for ensuring that @pos remains accessible until
153  * the start of the next iteration by, for example, bumping the css refcnt.
154  */
155 #define css_for_each_child(pos, parent)					\
156 	for ((pos) = css_next_child(NULL, (parent)); (pos);		\
157 	     (pos) = css_next_child((pos), (parent)))
158 
159 /**
160  * css_for_each_descendant_pre - pre-order walk of a css's descendants
161  * @pos: the css * to use as the loop cursor
162  * @root: css whose descendants to walk
163  *
164  * Walk @root's descendants.  @root is included in the iteration and the
165  * first node to be visited.  Must be called under rcu_read_lock().
166  *
167  * If a subsystem synchronizes ->css_online() and the start of iteration, a
168  * css which finished ->css_online() is guaranteed to be visible in the
169  * future iterations and will stay visible until the last reference is put.
170  * A css which hasn't finished ->css_online() or already finished
171  * ->css_offline() may show up during traversal.  It's each subsystem's
172  * responsibility to synchronize against on/offlining.
173  *
174  * For example, the following guarantees that a descendant can't escape
175  * state updates of its ancestors.
176  *
177  * my_online(@css)
178  * {
179  *	Lock @css's parent and @css;
180  *	Inherit state from the parent;
181  *	Unlock both.
182  * }
183  *
184  * my_update_state(@css)
185  * {
186  *	css_for_each_descendant_pre(@pos, @css) {
187  *		Lock @pos;
188  *		if (@pos == @css)
189  *			Update @css's state;
190  *		else
191  *			Verify @pos is alive and inherit state from its parent;
192  *		Unlock @pos;
193  *	}
194  * }
195  *
196  * As long as the inheriting step, including checking the parent state, is
197  * enclosed inside @pos locking, double-locking the parent isn't necessary
198  * while inheriting.  The state update to the parent is guaranteed to be
199  * visible by walking order and, as long as inheriting operations to the
200  * same @pos are atomic to each other, multiple updates racing each other
201  * still result in the correct state.  It's guaranateed that at least one
202  * inheritance happens for any css after the latest update to its parent.
203  *
204  * If checking parent's state requires locking the parent, each inheriting
205  * iteration should lock and unlock both @pos->parent and @pos.
206  *
207  * Alternatively, a subsystem may choose to use a single global lock to
208  * synchronize ->css_online() and ->css_offline() against tree-walking
209  * operations.
210  *
211  * It is allowed to temporarily drop RCU read lock during iteration.  The
212  * caller is responsible for ensuring that @pos remains accessible until
213  * the start of the next iteration by, for example, bumping the css refcnt.
214  */
215 #define css_for_each_descendant_pre(pos, css)				\
216 	for ((pos) = css_next_descendant_pre(NULL, (css)); (pos);	\
217 	     (pos) = css_next_descendant_pre((pos), (css)))
218 
219 /**
220  * css_for_each_descendant_post - post-order walk of a css's descendants
221  * @pos: the css * to use as the loop cursor
222  * @css: css whose descendants to walk
223  *
224  * Similar to css_for_each_descendant_pre() but performs post-order
225  * traversal instead.  @root is included in the iteration and the last
226  * node to be visited.
227  *
228  * If a subsystem synchronizes ->css_online() and the start of iteration, a
229  * css which finished ->css_online() is guaranteed to be visible in the
230  * future iterations and will stay visible until the last reference is put.
231  * A css which hasn't finished ->css_online() or already finished
232  * ->css_offline() may show up during traversal.  It's each subsystem's
233  * responsibility to synchronize against on/offlining.
234  *
235  * Note that the walk visibility guarantee example described in pre-order
236  * walk doesn't apply the same to post-order walks.
237  */
238 #define css_for_each_descendant_post(pos, css)				\
239 	for ((pos) = css_next_descendant_post(NULL, (css)); (pos);	\
240 	     (pos) = css_next_descendant_post((pos), (css)))
241 
242 /**
243  * cgroup_taskset_for_each - iterate cgroup_taskset
244  * @task: the loop cursor
245  * @dst_css: the destination css
246  * @tset: taskset to iterate
247  *
248  * @tset may contain multiple tasks and they may belong to multiple
249  * processes.
250  *
251  * On the v2 hierarchy, there may be tasks from multiple processes and they
252  * may not share the source or destination csses.
253  *
254  * On traditional hierarchies, when there are multiple tasks in @tset, if a
255  * task of a process is in @tset, all tasks of the process are in @tset.
256  * Also, all are guaranteed to share the same source and destination csses.
257  *
258  * Iteration is not in any specific order.
259  */
260 #define cgroup_taskset_for_each(task, dst_css, tset)			\
261 	for ((task) = cgroup_taskset_first((tset), &(dst_css));		\
262 	     (task);							\
263 	     (task) = cgroup_taskset_next((tset), &(dst_css)))
264 
265 /**
266  * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
267  * @leader: the loop cursor
268  * @dst_css: the destination css
269  * @tset: takset to iterate
270  *
271  * Iterate threadgroup leaders of @tset.  For single-task migrations, @tset
272  * may not contain any.
273  */
274 #define cgroup_taskset_for_each_leader(leader, dst_css, tset)		\
275 	for ((leader) = cgroup_taskset_first((tset), &(dst_css));	\
276 	     (leader);							\
277 	     (leader) = cgroup_taskset_next((tset), &(dst_css)))	\
278 		if ((leader) != (leader)->group_leader)			\
279 			;						\
280 		else
281 
282 /*
283  * Inline functions.
284  */
285 
286 /**
287  * css_get - obtain a reference on the specified css
288  * @css: target css
289  *
290  * The caller must already have a reference.
291  */
css_get(struct cgroup_subsys_state * css)292 static inline void css_get(struct cgroup_subsys_state *css)
293 {
294 	if (!(css->flags & CSS_NO_REF))
295 		percpu_ref_get(&css->refcnt);
296 }
297 
298 /**
299  * css_get_many - obtain references on the specified css
300  * @css: target css
301  * @n: number of references to get
302  *
303  * The caller must already have a reference.
304  */
css_get_many(struct cgroup_subsys_state * css,unsigned int n)305 static inline void css_get_many(struct cgroup_subsys_state *css, unsigned int n)
306 {
307 	if (!(css->flags & CSS_NO_REF))
308 		percpu_ref_get_many(&css->refcnt, n);
309 }
310 
311 /**
312  * css_tryget - try to obtain a reference on the specified css
313  * @css: target css
314  *
315  * Obtain a reference on @css unless it already has reached zero and is
316  * being released.  This function doesn't care whether @css is on or
317  * offline.  The caller naturally needs to ensure that @css is accessible
318  * but doesn't have to be holding a reference on it - IOW, RCU protected
319  * access is good enough for this function.  Returns %true if a reference
320  * count was successfully obtained; %false otherwise.
321  */
css_tryget(struct cgroup_subsys_state * css)322 static inline bool css_tryget(struct cgroup_subsys_state *css)
323 {
324 	if (!(css->flags & CSS_NO_REF))
325 		return percpu_ref_tryget(&css->refcnt);
326 	return true;
327 }
328 
329 /**
330  * css_tryget_online - try to obtain a reference on the specified css if online
331  * @css: target css
332  *
333  * Obtain a reference on @css if it's online.  The caller naturally needs
334  * to ensure that @css is accessible but doesn't have to be holding a
335  * reference on it - IOW, RCU protected access is good enough for this
336  * function.  Returns %true if a reference count was successfully obtained;
337  * %false otherwise.
338  */
css_tryget_online(struct cgroup_subsys_state * css)339 static inline bool css_tryget_online(struct cgroup_subsys_state *css)
340 {
341 	if (!(css->flags & CSS_NO_REF))
342 		return percpu_ref_tryget_live(&css->refcnt);
343 	return true;
344 }
345 
346 /**
347  * css_is_dying - test whether the specified css is dying
348  * @css: target css
349  *
350  * Test whether @css is in the process of offlining or already offline.  In
351  * most cases, ->css_online() and ->css_offline() callbacks should be
352  * enough; however, the actual offline operations are RCU delayed and this
353  * test returns %true also when @css is scheduled to be offlined.
354  *
355  * This is useful, for example, when the use case requires synchronous
356  * behavior with respect to cgroup removal.  cgroup removal schedules css
357  * offlining but the css can seem alive while the operation is being
358  * delayed.  If the delay affects user visible semantics, this test can be
359  * used to resolve the situation.
360  */
css_is_dying(struct cgroup_subsys_state * css)361 static inline bool css_is_dying(struct cgroup_subsys_state *css)
362 {
363 	return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);
364 }
365 
366 /**
367  * css_put - put a css reference
368  * @css: target css
369  *
370  * Put a reference obtained via css_get() and css_tryget_online().
371  */
css_put(struct cgroup_subsys_state * css)372 static inline void css_put(struct cgroup_subsys_state *css)
373 {
374 	if (!(css->flags & CSS_NO_REF))
375 		percpu_ref_put(&css->refcnt);
376 }
377 
378 /**
379  * css_put_many - put css references
380  * @css: target css
381  * @n: number of references to put
382  *
383  * Put references obtained via css_get() and css_tryget_online().
384  */
css_put_many(struct cgroup_subsys_state * css,unsigned int n)385 static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
386 {
387 	if (!(css->flags & CSS_NO_REF))
388 		percpu_ref_put_many(&css->refcnt, n);
389 }
390 
cgroup_put(struct cgroup * cgrp)391 static inline void cgroup_put(struct cgroup *cgrp)
392 {
393 	css_put(&cgrp->self);
394 }
395 
396 /**
397  * task_css_set_check - obtain a task's css_set with extra access conditions
398  * @task: the task to obtain css_set for
399  * @__c: extra condition expression to be passed to rcu_dereference_check()
400  *
401  * A task's css_set is RCU protected, initialized and exited while holding
402  * task_lock(), and can only be modified while holding both cgroup_mutex
403  * and task_lock() while the task is alive.  This macro verifies that the
404  * caller is inside proper critical section and returns @task's css_set.
405  *
406  * The caller can also specify additional allowed conditions via @__c, such
407  * as locks used during the cgroup_subsys::attach() methods.
408  */
409 #ifdef CONFIG_PROVE_RCU
410 extern struct mutex cgroup_mutex;
411 extern spinlock_t css_set_lock;
412 #define task_css_set_check(task, __c)					\
413 	rcu_dereference_check((task)->cgroups,				\
414 		lockdep_is_held(&cgroup_mutex) ||			\
415 		lockdep_is_held(&css_set_lock) ||			\
416 		((task)->flags & PF_EXITING) || (__c))
417 #else
418 #define task_css_set_check(task, __c)					\
419 	rcu_dereference((task)->cgroups)
420 #endif
421 
422 /**
423  * task_css_check - obtain css for (task, subsys) w/ extra access conds
424  * @task: the target task
425  * @subsys_id: the target subsystem ID
426  * @__c: extra condition expression to be passed to rcu_dereference_check()
427  *
428  * Return the cgroup_subsys_state for the (@task, @subsys_id) pair.  The
429  * synchronization rules are the same as task_css_set_check().
430  */
431 #define task_css_check(task, subsys_id, __c)				\
432 	task_css_set_check((task), (__c))->subsys[(subsys_id)]
433 
434 /**
435  * task_css_set - obtain a task's css_set
436  * @task: the task to obtain css_set for
437  *
438  * See task_css_set_check().
439  */
task_css_set(struct task_struct * task)440 static inline struct css_set *task_css_set(struct task_struct *task)
441 {
442 	return task_css_set_check(task, false);
443 }
444 
445 /**
446  * task_css - obtain css for (task, subsys)
447  * @task: the target task
448  * @subsys_id: the target subsystem ID
449  *
450  * See task_css_check().
451  */
task_css(struct task_struct * task,int subsys_id)452 static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
453 						   int subsys_id)
454 {
455 	return task_css_check(task, subsys_id, false);
456 }
457 
458 /**
459  * task_get_css - find and get the css for (task, subsys)
460  * @task: the target task
461  * @subsys_id: the target subsystem ID
462  *
463  * Find the css for the (@task, @subsys_id) combination, increment a
464  * reference on and return it.  This function is guaranteed to return a
465  * valid css.
466  */
467 static inline struct cgroup_subsys_state *
task_get_css(struct task_struct * task,int subsys_id)468 task_get_css(struct task_struct *task, int subsys_id)
469 {
470 	struct cgroup_subsys_state *css;
471 
472 	rcu_read_lock();
473 	while (true) {
474 		css = task_css(task, subsys_id);
475 		if (likely(css_tryget_online(css)))
476 			break;
477 		cpu_relax();
478 	}
479 	rcu_read_unlock();
480 	return css;
481 }
482 
483 /**
484  * task_css_is_root - test whether a task belongs to the root css
485  * @task: the target task
486  * @subsys_id: the target subsystem ID
487  *
488  * Test whether @task belongs to the root css on the specified subsystem.
489  * May be invoked in any context.
490  */
task_css_is_root(struct task_struct * task,int subsys_id)491 static inline bool task_css_is_root(struct task_struct *task, int subsys_id)
492 {
493 	return task_css_check(task, subsys_id, true) ==
494 		init_css_set.subsys[subsys_id];
495 }
496 
task_cgroup(struct task_struct * task,int subsys_id)497 static inline struct cgroup *task_cgroup(struct task_struct *task,
498 					 int subsys_id)
499 {
500 	return task_css(task, subsys_id)->cgroup;
501 }
502 
503 /**
504  * cgroup_is_descendant - test ancestry
505  * @cgrp: the cgroup to be tested
506  * @ancestor: possible ancestor of @cgrp
507  *
508  * Test whether @cgrp is a descendant of @ancestor.  It also returns %true
509  * if @cgrp == @ancestor.  This function is safe to call as long as @cgrp
510  * and @ancestor are accessible.
511  */
cgroup_is_descendant(struct cgroup * cgrp,struct cgroup * ancestor)512 static inline bool cgroup_is_descendant(struct cgroup *cgrp,
513 					struct cgroup *ancestor)
514 {
515 	if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)
516 		return false;
517 	return cgrp->ancestor_ids[ancestor->level] == ancestor->id;
518 }
519 
520 /**
521  * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
522  * @task: the task to be tested
523  * @ancestor: possible ancestor of @task's cgroup
524  *
525  * Tests whether @task's default cgroup hierarchy is a descendant of @ancestor.
526  * It follows all the same rules as cgroup_is_descendant, and only applies
527  * to the default hierarchy.
528  */
task_under_cgroup_hierarchy(struct task_struct * task,struct cgroup * ancestor)529 static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
530 					       struct cgroup *ancestor)
531 {
532 	struct css_set *cset = task_css_set(task);
533 
534 	return cgroup_is_descendant(cset->dfl_cgrp, ancestor);
535 }
536 
537 /* no synchronization, the result can only be used as a hint */
cgroup_is_populated(struct cgroup * cgrp)538 static inline bool cgroup_is_populated(struct cgroup *cgrp)
539 {
540 	return cgrp->populated_cnt;
541 }
542 
543 /* returns ino associated with a cgroup */
cgroup_ino(struct cgroup * cgrp)544 static inline ino_t cgroup_ino(struct cgroup *cgrp)
545 {
546 	return cgrp->kn->ino;
547 }
548 
549 /* cft/css accessors for cftype->write() operation */
of_cft(struct kernfs_open_file * of)550 static inline struct cftype *of_cft(struct kernfs_open_file *of)
551 {
552 	return of->kn->priv;
553 }
554 
555 struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
556 
557 /* cft/css accessors for cftype->seq_*() operations */
seq_cft(struct seq_file * seq)558 static inline struct cftype *seq_cft(struct seq_file *seq)
559 {
560 	return of_cft(seq->private);
561 }
562 
seq_css(struct seq_file * seq)563 static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
564 {
565 	return of_css(seq->private);
566 }
567 
568 /*
569  * Name / path handling functions.  All are thin wrappers around the kernfs
570  * counterparts and can be called under any context.
571  */
572 
cgroup_name(struct cgroup * cgrp,char * buf,size_t buflen)573 static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
574 {
575 	return kernfs_name(cgrp->kn, buf, buflen);
576 }
577 
cgroup_path(struct cgroup * cgrp,char * buf,size_t buflen)578 static inline int cgroup_path(struct cgroup *cgrp, char *buf, size_t buflen)
579 {
580 	return kernfs_path(cgrp->kn, buf, buflen);
581 }
582 
pr_cont_cgroup_name(struct cgroup * cgrp)583 static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
584 {
585 	pr_cont_kernfs_name(cgrp->kn);
586 }
587 
pr_cont_cgroup_path(struct cgroup * cgrp)588 static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
589 {
590 	pr_cont_kernfs_path(cgrp->kn);
591 }
592 
cgroup_init_kthreadd(void)593 static inline void cgroup_init_kthreadd(void)
594 {
595 	/*
596 	 * kthreadd is inherited by all kthreads, keep it in the root so
597 	 * that the new kthreads are guaranteed to stay in the root until
598 	 * initialization is finished.
599 	 */
600 	current->no_cgroup_migration = 1;
601 }
602 
cgroup_kthread_ready(void)603 static inline void cgroup_kthread_ready(void)
604 {
605 	/*
606 	 * This kthread finished initialization.  The creator should have
607 	 * set PF_NO_SETAFFINITY if this kthread should stay in the root.
608 	 */
609 	current->no_cgroup_migration = 0;
610 }
611 
612 #else /* !CONFIG_CGROUPS */
613 
614 struct cgroup_subsys_state;
615 struct cgroup;
616 
css_put(struct cgroup_subsys_state * css)617 static inline void css_put(struct cgroup_subsys_state *css) {}
cgroup_attach_task_all(struct task_struct * from,struct task_struct * t)618 static inline int cgroup_attach_task_all(struct task_struct *from,
619 					 struct task_struct *t) { return 0; }
cgroupstats_build(struct cgroupstats * stats,struct dentry * dentry)620 static inline int cgroupstats_build(struct cgroupstats *stats,
621 				    struct dentry *dentry) { return -EINVAL; }
622 
cgroup_fork(struct task_struct * p)623 static inline void cgroup_fork(struct task_struct *p) {}
cgroup_can_fork(struct task_struct * p)624 static inline int cgroup_can_fork(struct task_struct *p) { return 0; }
cgroup_cancel_fork(struct task_struct * p)625 static inline void cgroup_cancel_fork(struct task_struct *p) {}
cgroup_post_fork(struct task_struct * p)626 static inline void cgroup_post_fork(struct task_struct *p) {}
cgroup_exit(struct task_struct * p)627 static inline void cgroup_exit(struct task_struct *p) {}
cgroup_free(struct task_struct * p)628 static inline void cgroup_free(struct task_struct *p) {}
629 
cgroup_init_early(void)630 static inline int cgroup_init_early(void) { return 0; }
cgroup_init(void)631 static inline int cgroup_init(void) { return 0; }
cgroup_init_kthreadd(void)632 static inline void cgroup_init_kthreadd(void) {}
cgroup_kthread_ready(void)633 static inline void cgroup_kthread_ready(void) {}
634 
task_under_cgroup_hierarchy(struct task_struct * task,struct cgroup * ancestor)635 static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
636 					       struct cgroup *ancestor)
637 {
638 	return true;
639 }
640 #endif /* !CONFIG_CGROUPS */
641 
642 /*
643  * sock->sk_cgrp_data handling.  For more info, see sock_cgroup_data
644  * definition in cgroup-defs.h.
645  */
646 #ifdef CONFIG_SOCK_CGROUP_DATA
647 
648 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
649 extern spinlock_t cgroup_sk_update_lock;
650 #endif
651 
652 void cgroup_sk_alloc_disable(void);
653 void cgroup_sk_alloc(struct sock_cgroup_data *skcd);
654 void cgroup_sk_free(struct sock_cgroup_data *skcd);
655 
sock_cgroup_ptr(struct sock_cgroup_data * skcd)656 static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd)
657 {
658 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
659 	unsigned long v;
660 
661 	/*
662 	 * @skcd->val is 64bit but the following is safe on 32bit too as we
663 	 * just need the lower ulong to be written and read atomically.
664 	 */
665 	v = READ_ONCE(skcd->val);
666 
667 	if (v & 1)
668 		return &cgrp_dfl_root.cgrp;
669 
670 	return (struct cgroup *)(unsigned long)v ?: &cgrp_dfl_root.cgrp;
671 #else
672 	return (struct cgroup *)(unsigned long)skcd->val;
673 #endif
674 }
675 
676 #else	/* CONFIG_CGROUP_DATA */
677 
cgroup_sk_alloc(struct sock_cgroup_data * skcd)678 static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {}
cgroup_sk_free(struct sock_cgroup_data * skcd)679 static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {}
680 
681 #endif	/* CONFIG_CGROUP_DATA */
682 
683 struct cgroup_namespace {
684 	atomic_t		count;
685 	struct ns_common	ns;
686 	struct user_namespace	*user_ns;
687 	struct ucounts		*ucounts;
688 	struct css_set          *root_cset;
689 };
690 
691 extern struct cgroup_namespace init_cgroup_ns;
692 
693 #ifdef CONFIG_CGROUPS
694 
695 void free_cgroup_ns(struct cgroup_namespace *ns);
696 
697 struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
698 					struct user_namespace *user_ns,
699 					struct cgroup_namespace *old_ns);
700 
701 int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
702 		   struct cgroup_namespace *ns);
703 
704 #else /* !CONFIG_CGROUPS */
705 
free_cgroup_ns(struct cgroup_namespace * ns)706 static inline void free_cgroup_ns(struct cgroup_namespace *ns) { }
707 static inline struct cgroup_namespace *
copy_cgroup_ns(unsigned long flags,struct user_namespace * user_ns,struct cgroup_namespace * old_ns)708 copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
709 	       struct cgroup_namespace *old_ns)
710 {
711 	return old_ns;
712 }
713 
714 #endif /* !CONFIG_CGROUPS */
715 
get_cgroup_ns(struct cgroup_namespace * ns)716 static inline void get_cgroup_ns(struct cgroup_namespace *ns)
717 {
718 	if (ns)
719 		atomic_inc(&ns->count);
720 }
721 
put_cgroup_ns(struct cgroup_namespace * ns)722 static inline void put_cgroup_ns(struct cgroup_namespace *ns)
723 {
724 	if (ns && atomic_dec_and_test(&ns->count))
725 		free_cgroup_ns(ns);
726 }
727 
728 #endif /* _LINUX_CGROUP_H */
729