cap_syslog: don't use WARN_ONCE for CAP_SYS_ADMIN deprecation warning
[linux-2.6.git] / kernel / cgroup_freezer.c
index c287627..e691818 100644 (file)
@@ -153,13 +153,6 @@ static void freezer_destroy(struct cgroup_subsys *ss,
        kfree(cgroup_freezer(cgroup));
 }
 
-/* Task is frozen or will freeze immediately when next it gets woken */
-static bool is_task_frozen_enough(struct task_struct *task)
-{
-       return frozen(task) ||
-               (task_is_stopped_or_traced(task) && freezing(task));
-}
-
 /*
  * The call to cgroup_lock() in the freezer.state write method prevents
  * a write to that file racing against an attach, and hence the
@@ -167,7 +160,7 @@ 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, bool threadgroup)
+                             struct task_struct *task)
 {
        struct freezer *freezer;
 
@@ -179,26 +172,17 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
        if (freezer->state != CGROUP_THAWED)
                return -EBUSY;
 
+       return 0;
+}
+
+static int freezer_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
+{
        rcu_read_lock();
-       if (__cgroup_freezing_or_frozen(task)) {
+       if (__cgroup_freezing_or_frozen(tsk)) {
                rcu_read_unlock();
                return -EBUSY;
        }
        rcu_read_unlock();
-
-       if (threadgroup) {
-               struct task_struct *c;
-
-               rcu_read_lock();
-               list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
-                       if (__cgroup_freezing_or_frozen(c)) {
-                               rcu_read_unlock();
-                               return -EBUSY;
-                       }
-               }
-               rcu_read_unlock();
-       }
-
        return 0;
 }
 
@@ -236,31 +220,30 @@ static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
 /*
  * caller must hold freezer->lock
  */
-static void update_freezer_state(struct cgroup *cgroup,
+static void update_if_frozen(struct cgroup *cgroup,
                                 struct freezer *freezer)
 {
        struct cgroup_iter it;
        struct task_struct *task;
        unsigned int nfrozen = 0, ntotal = 0;
+       enum freezer_state old_state = freezer->state;
 
        cgroup_iter_start(cgroup, &it);
        while ((task = cgroup_iter_next(cgroup, &it))) {
                ntotal++;
-               if (is_task_frozen_enough(task))
+               if (frozen(task))
                        nfrozen++;
        }
 
-       /*
-        * Transition to FROZEN when no new tasks can be added ensures
-        * that we never exist in the FROZEN state while there are unfrozen
-        * tasks.
-        */
-       if (nfrozen == ntotal)
-               freezer->state = CGROUP_FROZEN;
-       else if (nfrozen > 0)
-               freezer->state = CGROUP_FREEZING;
-       else
-               freezer->state = CGROUP_THAWED;
+       if (old_state == CGROUP_THAWED) {
+               BUG_ON(nfrozen > 0);
+       } else if (old_state == CGROUP_FREEZING) {
+               if (nfrozen == ntotal)
+                       freezer->state = CGROUP_FROZEN;
+       } else { /* old_state == CGROUP_FROZEN */
+               BUG_ON(nfrozen != ntotal);
+       }
+
        cgroup_iter_end(cgroup, &it);
 }
 
@@ -279,7 +262,7 @@ static int freezer_read(struct cgroup *cgroup, struct cftype *cft,
        if (state == CGROUP_FREEZING) {
                /* We change from FREEZING to FROZEN lazily if the cgroup was
                 * only partially frozen when we exitted write. */
-               update_freezer_state(cgroup, freezer);
+               update_if_frozen(cgroup, freezer);
                state = freezer->state;
        }
        spin_unlock_irq(&freezer->lock);
@@ -301,7 +284,7 @@ static int try_to_freeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
        while ((task = cgroup_iter_next(cgroup, &it))) {
                if (!freeze_task(task, true))
                        continue;
-               if (is_task_frozen_enough(task))
+               if (frozen(task))
                        continue;
                if (!freezing(task) && !freezer_should_skip(task))
                        num_cant_freeze_now++;
@@ -335,7 +318,7 @@ static int freezer_change_state(struct cgroup *cgroup,
 
        spin_lock_irq(&freezer->lock);
 
-       update_freezer_state(cgroup, freezer);
+       update_if_frozen(cgroup, freezer);
        if (goal_state == freezer->state)
                goto out;
 
@@ -398,6 +381,9 @@ struct cgroup_subsys freezer_subsys = {
        .populate       = freezer_populate,
        .subsys_id      = freezer_subsys_id,
        .can_attach     = freezer_can_attach,
+       .can_attach_task = freezer_can_attach_task,
+       .pre_attach     = NULL,
+       .attach_task    = NULL,
        .attach         = NULL,
        .fork           = freezer_fork,
        .exit           = NULL,