Merge branch 'core-ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

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

diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 7fa476f..59e9ef6 100644 (file)
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -159,7 +159,7 @@ 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 +177,19 @@ 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;
 }
 
@@ -184,9 +197,20 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
 {
        struct freezer *freezer;
 
-       task_lock(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.
+        */
        freezer = task_freezer(task);
-       task_unlock(task);
+
+       /*
+        * 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);
@@ -331,7 +355,7 @@ 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;
@@ -350,6 +374,8 @@ 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));
 }