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 6605907..ce71ed5 100644 (file)
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/slab.h>
 #include <linux/cgroup.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
@@ -47,17 +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);
 }
 
 /*
@@ -85,10 +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
@@ -96,33 +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,
@@ -159,7 +168,7 @@ static bool is_task_frozen_enough(struct task_struct *task)
  */
 static int freezer_can_attach(struct cgroup_subsys *ss,
                              struct cgroup *new_cgroup,
-                             struct task_struct *task)
+                             struct task_struct *task, bool threadgroup)
 {
        struct freezer *freezer;
 
@@ -177,6 +186,19 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
        if (freezer->state == CGROUP_FROZEN)
                return -EBUSY;
 
+       if (threadgroup) {
+               struct task_struct *c;
+
+               rcu_read_lock();
+               list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
+                       if (is_task_frozen_enough(c)) {
+                               rcu_read_unlock();
+                               return -EBUSY;
+                       }
+               }
+               rcu_read_unlock();
+       }
+
        return 0;
 }
 
@@ -188,9 +210,19 @@ 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
+        * following check.
+        */
+       if (!freezer->css.cgroup->parent)
+               return;
 
        spin_lock_irq(&freezer->lock);
        BUG_ON(freezer->state == CGROUP_FROZEN);
@@ -335,7 +367,7 @@ static int freezer_write(struct cgroup *cgroup,
        else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
                goal_state = CGROUP_FROZEN;
        else
-               return -EIO;
+               return -EINVAL;
 
        if (!cgroup_lock_live_group(cgroup))
                return -ENODEV;
@@ -354,6 +386,8 @@ static struct cftype files[] = {
 
 static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
 {
+       if (!cgroup->parent)
+               return 0;
        return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
 }