include/linux/cgroup.h

   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
  91 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
  92 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
  93
  94 int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
  95 int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts);
  96 int cgroup_rm_cftypes(struct cftype *cfts);
  97 void cgroup_file_notify(struct cgroup_file *cfile);
  98
  99 char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
 100 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry);
 101 int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
 102                      struct pid *pid, struct task_struct *tsk);
 103
 104 void cgroup_fork(struct task_struct *p);
 105 extern int cgroup_can_fork(struct task_struct *p);
 106 extern void cgroup_cancel_fork(struct task_struct *p);
 107 extern void cgroup_post_fork(struct task_struct *p);
 108 void cgroup_exit(struct task_struct *p);
 109 void cgroup_free(struct task_struct *p);
 110
 111 int cgroup_init_early(void);
 112 int cgroup_init(void);
 113
 114 /*
 115  * Iteration helpers and macros.
 116  */
 117
 118 struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
 119                                            struct cgroup_subsys_state *parent);
 120 struct cgroup_subsys_state *css_next_descendant_pre(struct cgroup_subsys_state *pos,
 121                                                     struct cgroup_subsys_state *css);
 122 struct cgroup_subsys_state *css_rightmost_descendant(struct cgroup_subsys_state *pos);
 123 struct cgroup_subsys_state *css_next_descendant_post(struct cgroup_subsys_state *pos,
 124                                                      struct cgroup_subsys_state *css);
 125
 126 struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
 127                                          struct cgroup_subsys_state **dst_cssp);
 128 struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
 129                                         struct cgroup_subsys_state **dst_cssp);
 130
 131 void css_task_iter_start(struct cgroup_subsys_state *css,
 132                          struct css_task_iter *it);
 133 struct task_struct *css_task_iter_next(struct css_task_iter *it);
 134 void css_task_iter_end(struct css_task_iter *it);
 135
 136 /**
 137  * css_for_each_child - iterate through children of a css
 138  * @pos: the css * to use as the loop cursor
 139  * @parent: css whose children to walk
 140  *
 141  * Walk @parent's children.  Must be called under rcu_read_lock().
 142  *
 143  * If a subsystem synchronizes ->css_online() and the start of iteration, a
 144  * css which finished ->css_online() is guaranteed to be visible in the
 145  * future iterations and will stay visible until the last reference is put.
 146  * A css which hasn't finished ->css_online() or already finished
 147  * ->css_offline() may show up during traversal.  It's each subsystem's
 148  * responsibility to synchronize against on/offlining.
 149  *
 150  * It is allowed to temporarily drop RCU read lock during iteration.  The
 151  * caller is responsible for ensuring that @pos remains accessible until
 152  * the start of the next iteration by, for example, bumping the css refcnt.
 153  */
 154 #define css_for_each_child(pos, parent)                                 \
 155         for ((pos) = css_next_child(NULL, (parent)); (pos);             \
 156              (pos) = css_next_child((pos), (parent)))
 157
 158 /**
 159  * css_for_each_descendant_pre - pre-order walk of a css's descendants
 160  * @pos: the css * to use as the loop cursor
 161  * @root: css whose descendants to walk
 162  *
 163  * Walk @root's descendants.  @root is included in the iteration and the
 164  * first node to be visited.  Must be called under rcu_read_lock().
 165  *
 166  * If a subsystem synchronizes ->css_online() and the start of iteration, a
 167  * css which finished ->css_online() is guaranteed to be visible in the
 168  * future iterations and will stay visible until the last reference is put.
 169  * A css which hasn't finished ->css_online() or already finished
 170  * ->css_offline() may show up during traversal.  It's each subsystem's
 171  * responsibility to synchronize against on/offlining.
 172  *
 173  * For example, the following guarantees that a descendant can't escape
 174  * state updates of its ancestors.
 175  *
 176  * my_online(@css)
 177  * {
 178  *      Lock @css's parent and @css;
 179  *      Inherit state from the parent;
 180  *      Unlock both.
 181  * }
 182  *
 183  * my_update_state(@css)
 184  * {
 185  *      css_for_each_descendant_pre(@pos, @css) {
 186  *              Lock @pos;
 187  *              if (@pos == @css)
 188  *                      Update @css's state;
 189  *              else
 190  *                      Verify @pos is alive and inherit state from its parent;
 191  *              Unlock @pos;
 192  *      }
 193  * }
 194  *
 195  * As long as the inheriting step, including checking the parent state, is
 196  * enclosed inside @pos locking, double-locking the parent isn't necessary
 197  * while inheriting.  The state update to the parent is guaranteed to be
 198  * visible by walking order and, as long as inheriting operations to the
 199  * same @pos are atomic to each other, multiple updates racing each other
 200  * still result in the correct state.  It's guaranateed that at least one
 201  * inheritance happens for any css after the latest update to its parent.
 202  *
 203  * If checking parent's state requires locking the parent, each inheriting
 204  * iteration should lock and unlock both @pos->parent and @pos.
 205  *
 206  * Alternatively, a subsystem may choose to use a single global lock to
 207  * synchronize ->css_online() and ->css_offline() against tree-walking
 208  * operations.
 209  *
 210  * It is allowed to temporarily drop RCU read lock during iteration.  The
 211  * caller is responsible for ensuring that @pos remains accessible until
 212  * the start of the next iteration by, for example, bumping the css refcnt.
 213  */
 214 #define css_for_each_descendant_pre(pos, css)                           \
 215         for ((pos) = css_next_descendant_pre(NULL, (css)); (pos);       \
 216              (pos) = css_next_descendant_pre((pos), (css)))
 217
 218 /**
 219  * css_for_each_descendant_post - post-order walk of a css's descendants
 220  * @pos: the css * to use as the loop cursor
 221  * @css: css whose descendants to walk
 222  *
 223  * Similar to css_for_each_descendant_pre() but performs post-order
 224  * traversal instead.  @root is included in the iteration and the last
 225  * node to be visited.
 226  *
 227  * If a subsystem synchronizes ->css_online() and the start of iteration, a
 228  * css which finished ->css_online() is guaranteed to be visible in the
 229  * future iterations and will stay visible until the last reference is put.
 230  * A css which hasn't finished ->css_online() or already finished
 231  * ->css_offline() may show up during traversal.  It's each subsystem's
 232  * responsibility to synchronize against on/offlining.
 233  *
 234  * Note that the walk visibility guarantee example described in pre-order
 235  * walk doesn't apply the same to post-order walks.
 236  */
 237 #define css_for_each_descendant_post(pos, css)                          \
 238         for ((pos) = css_next_descendant_post(NULL, (css)); (pos);      \
 239              (pos) = css_next_descendant_post((pos), (css)))
 240
 241 /**
 242  * cgroup_taskset_for_each - iterate cgroup_taskset
 243  * @task: the loop cursor
 244  * @dst_css: the destination css
 245  * @tset: taskset to iterate
 246  *
 247  * @tset may contain multiple tasks and they may belong to multiple
 248  * processes.
 249  *
 250  * On the v2 hierarchy, there may be tasks from multiple processes and they
 251  * may not share the source or destination csses.
 252  *
 253  * On traditional hierarchies, when there are multiple tasks in @tset, if a
 254  * task of a process is in @tset, all tasks of the process are in @tset.
 255  * Also, all are guaranteed to share the same source and destination csses.
 256  *
 257  * Iteration is not in any specific order.
 258  */
 259 #define cgroup_taskset_for_each(task, dst_css, tset)                    \
 260         for ((task) = cgroup_taskset_first((tset), &(dst_css));         \
 261              (task);                                                    \
 262              (task) = cgroup_taskset_next((tset), &(dst_css)))
 263
 264 /**
 265  * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
 266  * @leader: the loop cursor
 267  * @dst_css: the destination css
 268  * @tset: takset to iterate
 269  *
 270  * Iterate threadgroup leaders of @tset.  For single-task migrations, @tset
 271  * may not contain any.
 272  */
 273 #define cgroup_taskset_for_each_leader(leader, dst_css, tset)           \
 274         for ((leader) = cgroup_taskset_first((tset), &(dst_css));       \
 275              (leader);                                                  \
 276              (leader) = cgroup_taskset_next((tset), &(dst_css)))        \
 277                 if ((leader) != (leader)->group_leader)                 \
 278                         ;                                               \
 279                 else
 280
 281 /*
 282  * Inline functions.
 283  */
 284
 285 /**
 286  * css_get - obtain a reference on the specified css
 287  * @css: target css
 288  *
 289  * The caller must already have a reference.
 290  */
 291 static inline void css_get(struct cgroup_subsys_state *css)
 292 {
 293         if (!(css->flags & CSS_NO_REF))
 294                 percpu_ref_get(&css->refcnt);
 295 }
 296
 297 /**
 298  * css_get_many - obtain references on the specified css
 299  * @css: target css
 300  * @n: number of references to get
 301  *
 302  * The caller must already have a reference.
 303  */
 304 static inline void css_get_many(struct cgroup_subsys_state *css, unsigned int n)
 305 {
 306         if (!(css->flags & CSS_NO_REF))
 307                 percpu_ref_get_many(&css->refcnt, n);
 308 }
 309
 310 /**
 311  * css_tryget - try to obtain a reference on the specified css
 312  * @css: target css
 313  *
 314  * Obtain a reference on @css unless it already has reached zero and is
 315  * being released.  This function doesn't care whether @css is on or
 316  * offline.  The caller naturally needs to ensure that @css is accessible
 317  * but doesn't have to be holding a reference on it - IOW, RCU protected
 318  * access is good enough for this function.  Returns %true if a reference
 319  * count was successfully obtained; %false otherwise.
 320  */
 321 static inline bool css_tryget(struct cgroup_subsys_state *css)
 322 {
 323         if (!(css->flags & CSS_NO_REF))
 324                 return percpu_ref_tryget(&css->refcnt);
 325         return true;
 326 }
 327
 328 /**
 329  * css_tryget_online - try to obtain a reference on the specified css if online
 330  * @css: target css
 331  *
 332  * Obtain a reference on @css if it's online.  The caller naturally needs
 333  * to ensure that @css is accessible but doesn't have to be holding a
 334  * reference on it - IOW, RCU protected access is good enough for this
 335  * function.  Returns %true if a reference count was successfully obtained;
 336  * %false otherwise.
 337  */
 338 static inline bool css_tryget_online(struct cgroup_subsys_state *css)
 339 {
 340         if (!(css->flags & CSS_NO_REF))
 341                 return percpu_ref_tryget_live(&css->refcnt);
 342         return true;
 343 }
 344
 345 /**
 346  * css_put - put a css reference
 347  * @css: target css
 348  *
 349  * Put a reference obtained via css_get() and css_tryget_online().
 350  */
 351 static inline void css_put(struct cgroup_subsys_state *css)
 352 {
 353         if (!(css->flags & CSS_NO_REF))
 354                 percpu_ref_put(&css->refcnt);
 355 }
 356
 357 /**
 358  * css_put_many - put css references
 359  * @css: target css
 360  * @n: number of references to put
 361  *
 362  * Put references obtained via css_get() and css_tryget_online().
 363  */
 364 static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n)
 365 {
 366         if (!(css->flags & CSS_NO_REF))
 367                 percpu_ref_put_many(&css->refcnt, n);
 368 }
 369
 370 static inline void cgroup_put(struct cgroup *cgrp)
 371 {
 372         css_put(&cgrp->self);
 373 }
 374
 375 /**
 376  * task_css_set_check - obtain a task's css_set with extra access conditions
 377  * @task: the task to obtain css_set for
 378  * @__c: extra condition expression to be passed to rcu_dereference_check()
 379  *
 380  * A task's css_set is RCU protected, initialized and exited while holding
 381  * task_lock(), and can only be modified while holding both cgroup_mutex
 382  * and task_lock() while the task is alive.  This macro verifies that the
 383  * caller is inside proper critical section and returns @task's css_set.
 384  *
 385  * The caller can also specify additional allowed conditions via @__c, such
 386  * as locks used during the cgroup_subsys::attach() methods.
 387  */
 388 #ifdef CONFIG_PROVE_RCU
 389 extern struct mutex cgroup_mutex;
 390 extern spinlock_t css_set_lock;
 391 #define task_css_set_check(task, __c)                                   \
 392         rcu_dereference_check((task)->cgroups,                          \
 393                 lockdep_is_held(&cgroup_mutex) ||                       \
 394                 lockdep_is_held(&css_set_lock) ||                       \
 395                 ((task)->flags & PF_EXITING) || (__c))
 396 #else
 397 #define task_css_set_check(task, __c)                                   \
 398         rcu_dereference((task)->cgroups)
 399 #endif
 400
 401 /**
 402  * task_css_check - obtain css for (task, subsys) w/ extra access conds
 403  * @task: the target task
 404  * @subsys_id: the target subsystem ID
 405  * @__c: extra condition expression to be passed to rcu_dereference_check()
 406  *
 407  * Return the cgroup_subsys_state for the (@task, @subsys_id) pair.  The
 408  * synchronization rules are the same as task_css_set_check().
 409  */
 410 #define task_css_check(task, subsys_id, __c)                            \
 411         task_css_set_check((task), (__c))->subsys[(subsys_id)]
 412
 413 /**
 414  * task_css_set - obtain a task's css_set
 415  * @task: the task to obtain css_set for
 416  *
 417  * See task_css_set_check().
 418  */
 419 static inline struct css_set *task_css_set(struct task_struct *task)
 420 {
 421         return task_css_set_check(task, false);
 422 }
 423
 424 /**
 425  * task_css - obtain css for (task, subsys)
 426  * @task: the target task
 427  * @subsys_id: the target subsystem ID
 428  *
 429  * See task_css_check().
 430  */
 431 static inline struct cgroup_subsys_state *task_css(struct task_struct *task,
 432                                                    int subsys_id)
 433 {
 434         return task_css_check(task, subsys_id, false);
 435 }
 436
 437 /**
 438  * task_get_css - find and get the css for (task, subsys)
 439  * @task: the target task
 440  * @subsys_id: the target subsystem ID
 441  *
 442  * Find the css for the (@task, @subsys_id) combination, increment a
 443  * reference on and return it.  This function is guaranteed to return a
 444  * valid css.
 445  */
 446 static inline struct cgroup_subsys_state *
 447 task_get_css(struct task_struct *task, int subsys_id)
 448 {
 449         struct cgroup_subsys_state *css;
 450
 451         rcu_read_lock();
 452         while (true) {
 453                 css = task_css(task, subsys_id);
 454                 if (likely(css_tryget_online(css)))
 455                         break;
 456                 cpu_relax();
 457         }
 458         rcu_read_unlock();
 459         return css;
 460 }
 461
 462 /**
 463  * task_css_is_root - test whether a task belongs to the root css
 464  * @task: the target task
 465  * @subsys_id: the target subsystem ID
 466  *
 467  * Test whether @task belongs to the root css on the specified subsystem.
 468  * May be invoked in any context.
 469  */
 470 static inline bool task_css_is_root(struct task_struct *task, int subsys_id)
 471 {
 472         return task_css_check(task, subsys_id, true) ==
 473                 init_css_set.subsys[subsys_id];
 474 }
 475
 476 static inline struct cgroup *task_cgroup(struct task_struct *task,
 477                                          int subsys_id)
 478 {
 479         return task_css(task, subsys_id)->cgroup;
 480 }
 481
 482 /**
 483  * cgroup_is_descendant - test ancestry
 484  * @cgrp: the cgroup to be tested
 485  * @ancestor: possible ancestor of @cgrp
 486  *
 487  * Test whether @cgrp is a descendant of @ancestor.  It also returns %true
 488  * if @cgrp == @ancestor.  This function is safe to call as long as @cgrp
 489  * and @ancestor are accessible.
 490  */
 491 static inline bool cgroup_is_descendant(struct cgroup *cgrp,
 492                                         struct cgroup *ancestor)
 493 {
 494         if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)
 495                 return false;
 496         return cgrp->ancestor_ids[ancestor->level] == ancestor->id;
 497 }
 498
 499 /* no synchronization, the result can only be used as a hint */
 500 static inline bool cgroup_is_populated(struct cgroup *cgrp)
 501 {
 502         return cgrp->populated_cnt;
 503 }
 504
 505 /* returns ino associated with a cgroup */
 506 static inline ino_t cgroup_ino(struct cgroup *cgrp)
 507 {
 508         return cgrp->kn->ino;
 509 }
 510
 511 /* cft/css accessors for cftype->write() operation */
 512 static inline struct cftype *of_cft(struct kernfs_open_file *of)
 513 {
 514         return of->kn->priv;
 515 }
 516
 517 struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
 518
 519 /* cft/css accessors for cftype->seq_*() operations */
 520 static inline struct cftype *seq_cft(struct seq_file *seq)
 521 {
 522         return of_cft(seq->private);
 523 }
 524
 525 static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
 526 {
 527         return of_css(seq->private);
 528 }
 529
 530 /*
 531  * Name / path handling functions.  All are thin wrappers around the kernfs
 532  * counterparts and can be called under any context.
 533  */
 534
 535 static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
 536 {
 537         return kernfs_name(cgrp->kn, buf, buflen);
 538 }
 539
 540 static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
 541                                               size_t buflen)
 542 {
 543         return kernfs_path(cgrp->kn, buf, buflen);
 544 }
 545
 546 static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
 547 {
 548         pr_cont_kernfs_name(cgrp->kn);
 549 }
 550
 551 static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
 552 {
 553         pr_cont_kernfs_path(cgrp->kn);
 554 }
 555
 556 #else /* !CONFIG_CGROUPS */
 557
 558 struct cgroup_subsys_state;
 559
 560 static inline void css_put(struct cgroup_subsys_state *css) {}
 561 static inline int cgroup_attach_task_all(struct task_struct *from,
 562                                          struct task_struct *t) { return 0; }
 563 static inline int cgroupstats_build(struct cgroupstats *stats,
 564                                     struct dentry *dentry) { return -EINVAL; }
 565
 566 static inline void cgroup_fork(struct task_struct *p) {}
 567 static inline int cgroup_can_fork(struct task_struct *p) { return 0; }
 568 static inline void cgroup_cancel_fork(struct task_struct *p) {}
 569 static inline void cgroup_post_fork(struct task_struct *p) {}
 570 static inline void cgroup_exit(struct task_struct *p) {}
 571 static inline void cgroup_free(struct task_struct *p) {}
 572
 573 static inline int cgroup_init_early(void) { return 0; }
 574 static inline int cgroup_init(void) { return 0; }
 575
 576 #endif /* !CONFIG_CGROUPS */
 577
 578 /*
 579  * sock->sk_cgrp_data handling.  For more info, see sock_cgroup_data
 580  * definition in cgroup-defs.h.
 581  */
 582 #ifdef CONFIG_SOCK_CGROUP_DATA
 583
 584 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
 585 extern spinlock_t cgroup_sk_update_lock;
 586 #endif
 587
 588 void cgroup_sk_alloc_disable(void);
 589 void cgroup_sk_alloc(struct sock_cgroup_data *skcd);
 590 void cgroup_sk_free(struct sock_cgroup_data *skcd);
 591
 592 static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd)
 593 {
 594 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
 595         unsigned long v;
 596
 597         /*
 598          * @skcd->val is 64bit but the following is safe on 32bit too as we
 599          * just need the lower ulong to be written and read atomically.
 600          */
 601         v = READ_ONCE(skcd->val);
 602
 603         if (v & 1)
 604                 return &cgrp_dfl_root.cgrp;
 605
 606         return (struct cgroup *)(unsigned long)v ?: &cgrp_dfl_root.cgrp;
 607 #else
 608         return (struct cgroup *)(unsigned long)skcd->val;
 609 #endif
 610 }
 611
 612 #else   /* CONFIG_CGROUP_DATA */
 613
 614 static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {}
 615 static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {}
 616
 617 #endif  /* CONFIG_CGROUP_DATA */
 618
 619 struct cgroup_namespace {
 620         atomic_t                count;
 621         struct ns_common        ns;
 622         struct user_namespace   *user_ns;
 623         struct css_set          *root_cset;
 624 };
 625
 626 extern struct cgroup_namespace init_cgroup_ns;
 627
 628 #ifdef CONFIG_CGROUPS
 629
 630 void free_cgroup_ns(struct cgroup_namespace *ns);
 631
 632 struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
 633                                         struct user_namespace *user_ns,
 634                                         struct cgroup_namespace *old_ns);
 635
 636 char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
 637                      struct cgroup_namespace *ns);
 638
 639 #else /* !CONFIG_CGROUPS */
 640
 641 static inline void free_cgroup_ns(struct cgroup_namespace *ns) { }
 642 static inline struct cgroup_namespace *
 643 copy_cgroup_ns(unsigned long flags, struct user_namespace *user_ns,
 644                struct cgroup_namespace *old_ns)
 645 {
 646         return old_ns;
 647 }
 648
 649 #endif /* !CONFIG_CGROUPS */
 650
 651 static inline void get_cgroup_ns(struct cgroup_namespace *ns)
 652 {
 653         if (ns)
 654                 atomic_inc(&ns->count);
 655 }
 656
 657 static inline void put_cgroup_ns(struct cgroup_namespace *ns)
 658 {
 659         if (ns && atomic_dec_and_test(&ns->count))
 660                 free_cgroup_ns(ns);
 661 }
 662
 663 #endif /* _LINUX_CGROUP_H */