mmc: s3c6410: enable ADMA feature in 6410 sdhci controller

[safe/jmp/linux-2.6] / kernel / cgroup_freezer.c

diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index d2ccd27..ce71ed5 100644 (file)
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -48,17 +48,20 @@ static inline struct freezer *task_freezer(struct task_struct *task)
                            struct freezer, css);
 }
 
-int cgroup_frozen(struct task_struct *task)
+int cgroup_freezing_or_frozen(struct task_struct *task)
 {
        struct freezer *freezer;
        enum freezer_state state;
 
        task_lock(task);
        freezer = task_freezer(task);
-       state = freezer->state;
+       if (!freezer->css.cgroup->parent)
+               state = CGROUP_THAWED; /* root cgroup can't be frozen */
+       else
+               state = freezer->state;
        task_unlock(task);
 
-       return state == CGROUP_FROZEN;
+       return (state == CGROUP_FREEZING) || (state == CGROUP_FROZEN);
 }
 
 /*
@@ -86,10 +89,10 @@ struct cgroup_subsys freezer_subsys;
 
 /* Locks taken and their ordering
  * ------------------------------
- * css_set_lock
  * cgroup_mutex (AKA cgroup_lock)
- * task->alloc_lock (AKA task_lock)
  * freezer->lock
+ * css_set_lock
+ * task->alloc_lock (AKA task_lock)
  * task->sighand->siglock
  *
  * cgroup code forces css_set_lock to be taken before task->alloc_lock
@@ -97,33 +100,38 @@ struct cgroup_subsys freezer_subsys;
  * freezer_create(), freezer_destroy():
  * cgroup_mutex [ by cgroup core ]
  *
- * can_attach():
- * cgroup_mutex
+ * freezer_can_attach():
+ * cgroup_mutex (held by caller of can_attach)
  *
- * cgroup_frozen():
+ * cgroup_freezing_or_frozen():
  * task->alloc_lock (to get task's cgroup)
  *
  * freezer_fork() (preserving fork() performance means can't take cgroup_mutex):
- * task->alloc_lock (to get task's cgroup)
  * freezer->lock
  *  sighand->siglock (if the cgroup is freezing)
  *
  * freezer_read():
  * cgroup_mutex
  *  freezer->lock
+ *   write_lock css_set_lock (cgroup iterator start)
+ *    task->alloc_lock
  *   read_lock css_set_lock (cgroup iterator start)
  *
  * freezer_write() (freeze):
  * cgroup_mutex
  *  freezer->lock
+ *   write_lock css_set_lock (cgroup iterator start)
+ *    task->alloc_lock
  *   read_lock css_set_lock (cgroup iterator start)
- *    sighand->siglock
+ *    sighand->siglock (fake signal delivery inside freeze_task())
  *
  * freezer_write() (unfreeze):
  * cgroup_mutex
  *  freezer->lock
+ *   write_lock css_set_lock (cgroup iterator start)
+ *    task->alloc_lock
  *   read_lock css_set_lock (cgroup iterator start)
- *    task->alloc_lock (to prevent races with freeze_task())
+ *    task->alloc_lock (inside thaw_process(), prevents race with refrigerator())
  *     sighand->siglock
  */
 static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
@@ -202,9 +210,12 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
         * No lock is needed, since the task isn't on tasklist yet,
         * so it can't be moved to another cgroup, which means the
         * freezer won't be removed and will be valid during this
-        * function call.
+        * function call.  Nevertheless, apply RCU read-side critical
+        * section to suppress RCU lockdep false positives.
         */
+       rcu_read_lock();
        freezer = task_freezer(task);
+       rcu_read_unlock();
 
        /*
         * The root cgroup is non-freezable, so we can skip the