cgroup_freezer: prepare freezer_change_state() for full hierarchy support
* Make freezer_change_state() take bool @freeze instead of enum
freezer_state.
* Separate out freezer_apply_state() out of freezer_change_state().
This makes freezer_change_state() a rather silly thin wrapper. It
will be filled with hierarchy handling later on.
This patch doesn't introduce any behavior change.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index 975b3d8..2690830 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -247,45 +247,57 @@
cgroup_iter_end(cgroup, &it);
}
-static void freezer_change_state(struct freezer *freezer,
- enum freezer_state goal_state)
+/**
+ * freezer_apply_state - apply state change to a single cgroup_freezer
+ * @freezer: freezer to apply state change to
+ * @freeze: whether to freeze or unfreeze
+ */
+static void freezer_apply_state(struct freezer *freezer, bool freeze)
{
/* also synchronizes against task migration, see freezer_attach() */
- spin_lock_irq(&freezer->lock);
+ lockdep_assert_held(&freezer->lock);
- switch (goal_state) {
- case CGROUP_THAWED:
- if (freezer->state != CGROUP_THAWED)
- atomic_dec(&system_freezing_cnt);
- freezer->state = CGROUP_THAWED;
- unfreeze_cgroup(freezer);
- break;
- case CGROUP_FROZEN:
+ if (freeze) {
if (freezer->state == CGROUP_THAWED)
atomic_inc(&system_freezing_cnt);
freezer->state = CGROUP_FREEZING;
freeze_cgroup(freezer);
- break;
- default:
- BUG();
+ } else {
+ if (freezer->state != CGROUP_THAWED)
+ atomic_dec(&system_freezing_cnt);
+ freezer->state = CGROUP_THAWED;
+ unfreeze_cgroup(freezer);
}
+}
+/**
+ * freezer_change_state - change the freezing state of a cgroup_freezer
+ * @freezer: freezer of interest
+ * @freeze: whether to freeze or thaw
+ *
+ * Freeze or thaw @cgroup according to @freeze.
+ */
+static void freezer_change_state(struct freezer *freezer, bool freeze)
+{
+ /* update @freezer */
+ spin_lock_irq(&freezer->lock);
+ freezer_apply_state(freezer, freeze);
spin_unlock_irq(&freezer->lock);
}
static int freezer_write(struct cgroup *cgroup, struct cftype *cft,
const char *buffer)
{
- enum freezer_state goal_state;
+ bool freeze;
if (strcmp(buffer, freezer_state_strs[CGROUP_THAWED]) == 0)
- goal_state = CGROUP_THAWED;
+ freeze = false;
else if (strcmp(buffer, freezer_state_strs[CGROUP_FROZEN]) == 0)
- goal_state = CGROUP_FROZEN;
+ freeze = true;
else
return -EINVAL;
- freezer_change_state(cgroup_freezer(cgroup), goal_state);
+ freezer_change_state(cgroup_freezer(cgroup), freeze);
return 0;
}