struct task_struct *task)
{
struct freezer *freezer;
- int retval;
- /* Anything frozen can't move or be moved to/from */
+ /*
+ * Anything frozen can't move or be moved to/from.
+ *
+ * Since orig_freezer->state == FROZEN means that @task has been
+ * frozen, so it's sufficient to check the latter condition.
+ */
if (is_task_frozen_enough(task))
return -EBUSY;
if (freezer->state == CGROUP_FROZEN)
return -EBUSY;
- retval = 0;
- task_lock(task);
- freezer = task_freezer(task);
- if (freezer->state == CGROUP_FROZEN)
- retval = -EBUSY;
- task_unlock(task);
- return retval;
+ return 0;
}
static void freezer_fork(struct cgroup_subsys *ss, struct task_struct *task)
freezer = task_freezer(task);
task_unlock(task);
- BUG_ON(freezer->state == CGROUP_FROZEN);
spin_lock_irq(&freezer->lock);
+ BUG_ON(freezer->state == CGROUP_FROZEN);
+
/* Locking avoids race with FREEZING -> THAWED transitions. */
if (freezer->state == CGROUP_FREEZING)
freeze_task(task, true);
/*
* caller must hold freezer->lock
*/
-static void check_if_frozen(struct cgroup *cgroup,
- struct freezer *freezer)
+static void update_freezer_state(struct cgroup *cgroup,
+ struct freezer *freezer)
{
struct cgroup_iter it;
struct task_struct *task;
*/
if (nfrozen == ntotal)
freezer->state = CGROUP_FROZEN;
+ else if (nfrozen > 0)
+ freezer->state = CGROUP_FREEZING;
+ else
+ freezer->state = CGROUP_THAWED;
cgroup_iter_end(cgroup, &it);
}
if (state == CGROUP_FREEZING) {
/* We change from FREEZING to FROZEN lazily if the cgroup was
* only partially frozen when we exitted write. */
- check_if_frozen(cgroup, freezer);
+ update_freezer_state(cgroup, freezer);
state = freezer->state;
}
spin_unlock_irq(&freezer->lock);
return num_cant_freeze_now ? -EBUSY : 0;
}
-static int unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
+static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
{
struct cgroup_iter it;
struct task_struct *task;
cgroup_iter_start(cgroup, &it);
while ((task = cgroup_iter_next(cgroup, &it))) {
- int do_wake;
-
- task_lock(task);
- do_wake = __thaw_process(task);
- task_unlock(task);
- if (do_wake)
- wake_up_process(task);
+ thaw_process(task);
}
cgroup_iter_end(cgroup, &it);
- freezer->state = CGROUP_THAWED;
- return 0;
+ freezer->state = CGROUP_THAWED;
}
static int freezer_change_state(struct cgroup *cgroup,
int retval = 0;
freezer = cgroup_freezer(cgroup);
+
spin_lock_irq(&freezer->lock);
- check_if_frozen(cgroup, freezer); /* may update freezer->state */
+
+ update_freezer_state(cgroup, freezer);
if (goal_state == freezer->state)
goto out;
- switch (freezer->state) {
+
+ switch (goal_state) {
case CGROUP_THAWED:
- retval = try_to_freeze_cgroup(cgroup, freezer);
+ unfreeze_cgroup(cgroup, freezer);
break;
- case CGROUP_FREEZING:
- if (goal_state == CGROUP_FROZEN) {
- /* Userspace is retrying after
- * "/bin/echo FROZEN > freezer.state" returned -EBUSY */
- retval = try_to_freeze_cgroup(cgroup, freezer);
- break;
- }
- /* state == FREEZING and goal_state == THAWED, so unfreeze */
case CGROUP_FROZEN:
- retval = unfreeze_cgroup(cgroup, freezer);
+ retval = try_to_freeze_cgroup(cgroup, freezer);
break;
default:
- break;
+ BUG();
}
out:
spin_unlock_irq(&freezer->lock);