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authorIngo Molnar <mingo@elte.hu>2009-01-11 03:43:52 +0100
committerIngo Molnar <mingo@elte.hu>2009-01-11 03:43:52 +0100
commit99cd7074891f87c49660e3b2880564324a4733ac (patch)
tree903d2665bcb445f1f265d1adf7a99f265bcefc15 /include/linux/cgroup.h
parente8a9cbf6ae620d9e5ba9cb42001c033287a284a3 (diff)
parentc59765042f53a79a7a65585042ff463b69cb248c (diff)
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Merge commit 'v2.6.29-rc1' into tracing/urgent
Diffstat (limited to 'include/linux/cgroup.h')
-rw-r--r--include/linux/cgroup.h75
1 files changed, 53 insertions, 22 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 1164963c3a85..e267e62827bb 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -52,9 +52,9 @@ struct cgroup_subsys_state {
* hierarchy structure */
struct cgroup *cgroup;
- /* State maintained by the cgroup system to allow
- * subsystems to be "busy". Should be accessed via css_get()
- * and css_put() */
+ /* State maintained by the cgroup system to allow subsystems
+ * to be "busy". Should be accessed via css_get(),
+ * css_tryget() and and css_put(). */
atomic_t refcnt;
@@ -64,11 +64,14 @@ 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 */
};
/*
- * Call css_get() to hold a reference on the cgroup;
- *
+ * Call css_get() to hold a reference on the css; it can be used
+ * for a reference obtained via:
+ * - an existing ref-counted reference to the css
+ * - task->cgroups for a locked task
*/
static inline void css_get(struct cgroup_subsys_state *css)
@@ -77,9 +80,32 @@ static inline void css_get(struct cgroup_subsys_state *css)
if (!test_bit(CSS_ROOT, &css->flags))
atomic_inc(&css->refcnt);
}
+
+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
+ * the css has been destroyed.
+ */
+
+static inline bool css_tryget(struct cgroup_subsys_state *css)
+{
+ if (test_bit(CSS_ROOT, &css->flags))
+ return true;
+ while (!atomic_inc_not_zero(&css->refcnt)) {
+ if (test_bit(CSS_REMOVED, &css->flags))
+ return false;
+ }
+ return true;
+}
+
/*
* css_put() should be called to release a reference taken by
- * css_get()
+ * css_get() or css_tryget()
*/
extern void __css_put(struct cgroup_subsys_state *css);
@@ -116,7 +142,7 @@ struct cgroup {
struct list_head children; /* my children */
struct cgroup *parent; /* my parent */
- struct dentry *dentry; /* cgroup fs entry */
+ struct dentry *dentry; /* cgroup fs entry, RCU protected */
/* Private pointers for each registered subsystem */
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
@@ -145,6 +171,9 @@ struct cgroup {
int pids_use_count;
/* Length of the current tasks_pids array */
int pids_length;
+
+ /* For RCU-protected deletion */
+ struct rcu_head rcu_head;
};
/* A css_set is a structure holding pointers to a set of
@@ -329,13 +358,7 @@ struct cgroup_subsys {
struct cgroup *cgrp);
void (*post_clone)(struct cgroup_subsys *ss, struct cgroup *cgrp);
void (*bind)(struct cgroup_subsys *ss, struct cgroup *root);
- /*
- * This routine is called with the task_lock of mm->owner held
- */
- void (*mm_owner_changed)(struct cgroup_subsys *ss,
- struct cgroup *old,
- struct cgroup *new,
- struct task_struct *p);
+
int subsys_id;
int active;
int disabled;
@@ -343,9 +366,23 @@ struct cgroup_subsys {
#define MAX_CGROUP_TYPE_NAMELEN 32
const char *name;
- /* Protected by RCU */
- struct cgroupfs_root *root;
+ /*
+ * Protects sibling/children links of cgroups in this
+ * hierarchy, plus protects which hierarchy (or none) the
+ * subsystem is a part of (i.e. root/sibling). To avoid
+ * potential deadlocks, the following operations should not be
+ * undertaken while holding any hierarchy_mutex:
+ *
+ * - allocating memory
+ * - initiating hotplug events
+ */
+ struct mutex hierarchy_mutex;
+ /*
+ * Link to parent, and list entry in parent's children.
+ * Protected by this->hierarchy_mutex and cgroup_lock()
+ */
+ struct cgroupfs_root *root;
struct list_head sibling;
};
@@ -400,9 +437,6 @@ void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);
int cgroup_scan_tasks(struct cgroup_scanner *scan);
int cgroup_attach_task(struct cgroup *, struct task_struct *);
-void cgroup_mm_owner_callbacks(struct task_struct *old,
- struct task_struct *new);
-
#else /* !CONFIG_CGROUPS */
static inline int cgroup_init_early(void) { return 0; }
@@ -420,9 +454,6 @@ static inline int cgroupstats_build(struct cgroupstats *stats,
return -EINVAL;
}
-static inline void cgroup_mm_owner_callbacks(struct task_struct *old,
- struct task_struct *new) {}
-
#endif /* !CONFIG_CGROUPS */
#endif /* _LINUX_CGROUP_H */