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Commit 04a4ec32 authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
parent bcd66c89

kernel/cgroup_freezer.c

+30 −18
Original line number Diff line number Diff line
@@ -247,45 +247,57 @@ static void unfreeze_cgroup(struct freezer *freezer) 
	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;

}