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-rw-r--r--include/linux/cgroup.h167
1 files changed, 114 insertions, 53 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f8a030ced0c7..7d73905dcba2 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -12,6 +12,7 @@
#include <linux/cpumask.h>
#include <linux/nodemask.h>
#include <linux/rcupdate.h>
+#include <linux/rculist.h>
#include <linux/cgroupstats.h>
#include <linux/prio_heap.h>
#include <linux/rwsem.h>
@@ -34,7 +35,6 @@ extern int cgroup_lock_is_held(void);
extern bool cgroup_lock_live_group(struct cgroup *cgrp);
extern void cgroup_unlock(void);
extern void cgroup_fork(struct task_struct *p);
-extern void cgroup_fork_callbacks(struct task_struct *p);
extern void cgroup_post_fork(struct task_struct *p);
extern void cgroup_exit(struct task_struct *p, int run_callbacks);
extern int cgroupstats_build(struct cgroupstats *stats,
@@ -66,7 +66,7 @@ struct cgroup_subsys_state {
/*
* State maintained by the cgroup system to allow subsystems
* to be "busy". Should be accessed via css_get(),
- * css_tryget() and and css_put().
+ * css_tryget() and css_put().
*/
atomic_t refcnt;
@@ -81,9 +81,8 @@ struct cgroup_subsys_state {
/* bits in struct cgroup_subsys_state flags field */
enum {
- CSS_ROOT, /* This CSS is the root of the subsystem */
- CSS_REMOVED, /* This CSS is dead */
- CSS_CLEAR_CSS_REFS, /* @ss->__DEPRECATED_clear_css_refs */
+ CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */
+ CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
};
/* Caller must verify that the css is not for root cgroup */
@@ -102,15 +101,10 @@ static inline void __css_get(struct cgroup_subsys_state *css, int count)
static inline void css_get(struct cgroup_subsys_state *css)
{
/* We don't need to reference count the root state */
- if (!test_bit(CSS_ROOT, &css->flags))
+ if (!(css->flags & CSS_ROOT))
__css_get(css, 1);
}
-static inline bool css_is_removed(struct cgroup_subsys_state *css)
-{
- return test_bit(CSS_REMOVED, &css->flags);
-}
-
/*
* Call css_tryget() to take a reference on a css if your existing
* (known-valid) reference isn't already ref-counted. Returns false if
@@ -120,7 +114,7 @@ static inline bool css_is_removed(struct cgroup_subsys_state *css)
extern bool __css_tryget(struct cgroup_subsys_state *css);
static inline bool css_tryget(struct cgroup_subsys_state *css)
{
- if (test_bit(CSS_ROOT, &css->flags))
+ if (css->flags & CSS_ROOT)
return true;
return __css_tryget(css);
}
@@ -133,7 +127,7 @@ static inline bool css_tryget(struct cgroup_subsys_state *css)
extern void __css_put(struct cgroup_subsys_state *css);
static inline void css_put(struct cgroup_subsys_state *css)
{
- if (!test_bit(CSS_ROOT, &css->flags))
+ if (!(css->flags & CSS_ROOT))
__css_put(css);
}
@@ -149,13 +143,11 @@ enum {
/* Control Group requires release notifications to userspace */
CGRP_NOTIFY_ON_RELEASE,
/*
- * A thread in rmdir() is wating for this cgroup.
- */
- CGRP_WAIT_ON_RMDIR,
- /*
- * Clone cgroup values when creating a new child cgroup
+ * Clone the parent's configuration when creating a new child
+ * cpuset cgroup. For historical reasons, this option can be
+ * specified at mount time and thus is implemented here.
*/
- CGRP_CLONE_CHILDREN,
+ CGRP_CPUSET_CLONE_CHILDREN,
};
struct cgroup {
@@ -167,6 +159,8 @@ struct cgroup {
*/
atomic_t count;
+ int id; /* ida allocated in-hierarchy ID */
+
/*
* We link our 'sibling' struct into our parent's 'children'.
* Our children link their 'sibling' into our 'children'.
@@ -176,7 +170,7 @@ struct cgroup {
struct list_head files; /* my files */
struct cgroup *parent; /* my parent */
- struct dentry __rcu *dentry; /* cgroup fs entry, RCU protected */
+ struct dentry *dentry; /* cgroup fs entry, RCU protected */
/* Private pointers for each registered subsystem */
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
@@ -282,7 +276,7 @@ struct cgroup_map_cb {
/* cftype->flags */
#define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */
-#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create onp root cg */
+#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create on root cg */
#define MAX_CFTYPE_NAME 64
@@ -422,23 +416,6 @@ int cgroup_task_count(const struct cgroup *cgrp);
int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
/*
- * When the subsys has to access css and may add permanent refcnt to css,
- * it should take care of racy conditions with rmdir(). Following set of
- * functions, is for stop/restart rmdir if necessary.
- * Because these will call css_get/put, "css" should be alive css.
- *
- * cgroup_exclude_rmdir();
- * ...do some jobs which may access arbitrary empty cgroup
- * cgroup_release_and_wakeup_rmdir();
- *
- * When someone removes a cgroup while cgroup_exclude_rmdir() holds it,
- * it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up.
- */
-
-void cgroup_exclude_rmdir(struct cgroup_subsys_state *css);
-void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css);
-
-/*
* Control Group taskset, used to pass around set of tasks to cgroup_subsys
* methods.
*/
@@ -466,16 +443,17 @@ int cgroup_taskset_size(struct cgroup_taskset *tset);
*/
struct cgroup_subsys {
- struct cgroup_subsys_state *(*create)(struct cgroup *cgrp);
- int (*pre_destroy)(struct cgroup *cgrp);
- void (*destroy)(struct cgroup *cgrp);
+ struct cgroup_subsys_state *(*css_alloc)(struct cgroup *cgrp);
+ int (*css_online)(struct cgroup *cgrp);
+ void (*css_offline)(struct cgroup *cgrp);
+ void (*css_free)(struct cgroup *cgrp);
+
int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset);
void (*fork)(struct task_struct *task);
void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp,
struct task_struct *task);
- void (*post_clone)(struct cgroup *cgrp);
void (*bind)(struct cgroup *root);
int subsys_id;
@@ -489,17 +467,6 @@ struct cgroup_subsys {
bool use_id;
/*
- * If %true, cgroup removal will try to clear css refs by retrying
- * ss->pre_destroy() until there's no css ref left. This behavior
- * is strictly for backward compatibility and will be removed as
- * soon as the current user (memcg) is updated.
- *
- * If %false, ss->pre_destroy() can't fail and cgroup removal won't
- * wait for css refs to drop to zero before proceeding.
- */
- bool __DEPRECATED_clear_css_refs;
-
- /*
* If %false, this subsystem is properly hierarchical -
* configuration, resource accounting and restriction on a parent
* cgroup cover those of its children. If %true, hierarchy support
@@ -572,6 +539,100 @@ static inline struct cgroup* task_cgroup(struct task_struct *task,
return task_subsys_state(task, subsys_id)->cgroup;
}
+/**
+ * cgroup_for_each_child - iterate through children of a cgroup
+ * @pos: the cgroup * to use as the loop cursor
+ * @cgroup: cgroup whose children to walk
+ *
+ * Walk @cgroup's children. Must be called under rcu_read_lock(). A child
+ * cgroup which hasn't finished ->css_online() or already has finished
+ * ->css_offline() may show up during traversal and it's each subsystem's
+ * responsibility to verify that each @pos is alive.
+ *
+ * If a subsystem synchronizes against the parent in its ->css_online() and
+ * before starting iterating, a cgroup which finished ->css_online() is
+ * guaranteed to be visible in the future iterations.
+ */
+#define cgroup_for_each_child(pos, cgroup) \
+ list_for_each_entry_rcu(pos, &(cgroup)->children, sibling)
+
+struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
+ struct cgroup *cgroup);
+
+/**
+ * cgroup_for_each_descendant_pre - pre-order walk of a cgroup's descendants
+ * @pos: the cgroup * to use as the loop cursor
+ * @cgroup: cgroup whose descendants to walk
+ *
+ * Walk @cgroup's descendants. Must be called under rcu_read_lock(). A
+ * descendant cgroup which hasn't finished ->css_online() or already has
+ * finished ->css_offline() may show up during traversal and it's each
+ * subsystem's responsibility to verify that each @pos is alive.
+ *
+ * If a subsystem synchronizes against the parent in its ->css_online() and
+ * before starting iterating, and synchronizes against @pos on each
+ * iteration, any descendant cgroup which finished ->css_offline() is
+ * guaranteed to be visible in the future iterations.
+ *
+ * In other words, the following guarantees that a descendant can't escape
+ * state updates of its ancestors.
+ *
+ * my_online(@cgrp)
+ * {
+ * Lock @cgrp->parent and @cgrp;
+ * Inherit state from @cgrp->parent;
+ * Unlock both.
+ * }
+ *
+ * my_update_state(@cgrp)
+ * {
+ * Lock @cgrp;
+ * Update @cgrp's state;
+ * Unlock @cgrp;
+ *
+ * cgroup_for_each_descendant_pre(@pos, @cgrp) {
+ * Lock @pos;
+ * Verify @pos is alive and inherit state from @pos->parent;
+ * Unlock @pos;
+ * }
+ * }
+ *
+ * As long as the inheriting step, including checking the parent state, is
+ * enclosed inside @pos locking, double-locking the parent isn't necessary
+ * while inheriting. The state update to the parent is guaranteed to be
+ * visible by walking order and, as long as inheriting operations to the
+ * same @pos are atomic to each other, multiple updates racing each other
+ * still result in the correct state. It's guaranateed that at least one
+ * inheritance happens for any cgroup after the latest update to its
+ * parent.
+ *
+ * If checking parent's state requires locking the parent, each inheriting
+ * iteration should lock and unlock both @pos->parent and @pos.
+ *
+ * Alternatively, a subsystem may choose to use a single global lock to
+ * synchronize ->css_online() and ->css_offline() against tree-walking
+ * operations.
+ */
+#define cgroup_for_each_descendant_pre(pos, cgroup) \
+ for (pos = cgroup_next_descendant_pre(NULL, (cgroup)); (pos); \
+ pos = cgroup_next_descendant_pre((pos), (cgroup)))
+
+struct cgroup *cgroup_next_descendant_post(struct cgroup *pos,
+ struct cgroup *cgroup);
+
+/**
+ * cgroup_for_each_descendant_post - post-order walk of a cgroup's descendants
+ * @pos: the cgroup * to use as the loop cursor
+ * @cgroup: cgroup whose descendants to walk
+ *
+ * Similar to cgroup_for_each_descendant_pre() but performs post-order
+ * traversal instead. Note that the walk visibility guarantee described in
+ * pre-order walk doesn't apply the same to post-order walks.
+ */
+#define cgroup_for_each_descendant_post(pos, cgroup) \
+ for (pos = cgroup_next_descendant_post(NULL, (cgroup)); (pos); \
+ pos = cgroup_next_descendant_post((pos), (cgroup)))
+
/* A cgroup_iter should be treated as an opaque object */
struct cgroup_iter {
struct list_head *cg_link;

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