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Commit a2252180 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup_freezer: introduce CGROUP_FREEZING_[SELF|PARENT] 



Introduce FREEZING_SELF and FREEZING_PARENT and make FREEZING OR of
the two flags.  This is to prepare for full hierarchy support.

freezer_apply_date() is updated such that it can handle setting and
clearing of both flags.  The two flags are also exposed to userland
via read-only files self_freezing and parent_freezing.

Other than the added cgroupfs files, 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 d6a2fe13

kernel/cgroup_freezer.c

+47 −8
Original line number Diff line number Diff line
@@ -23,8 +23,12 @@ 
#include <linux/seq_file.h>



enum freezer_state_flags {

	CGROUP_FREEZING		= (1 << 1), /* this freezer is freezing */

	CGROUP_FREEZING_SELF	= (1 << 1), /* this freezer is freezing */

	CGROUP_FREEZING_PARENT	= (1 << 2), /* the parent freezer is freezing */

	CGROUP_FROZEN		= (1 << 3), /* this and its descendants frozen */



	/* mask for all FREEZING flags */

	CGROUP_FREEZING		= CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT,

};



struct freezer {
@@ -245,8 +249,13 @@ static void unfreeze_cgroup(struct freezer *freezer) 
 * freezer_apply_state - apply state change to a single cgroup_freezer

 * @freezer: freezer to apply state change to

 * @freeze: whether to freeze or unfreeze

 * @state: CGROUP_FREEZING_* flag to set or clear

 *

 * Set or clear @state on @cgroup according to @freeze, and perform

 * freezing or thawing as necessary.

 */

static void freezer_apply_state(struct freezer *freezer, bool freeze)

static void freezer_apply_state(struct freezer *freezer, bool freeze,

				unsigned int state)

{

	/* also synchronizes against task migration, see freezer_attach() */

	lockdep_assert_held(&freezer->lock);
@@ -254,15 +263,21 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze) 
	if (freeze) {

		if (!(freezer->state & CGROUP_FREEZING))

			atomic_inc(&system_freezing_cnt);

		freezer->state |= CGROUP_FREEZING;

		freezer->state |= state;

		freeze_cgroup(freezer);

	} else {

		if (freezer->state & CGROUP_FREEZING)

		bool was_freezing = freezer->state & CGROUP_FREEZING;



		freezer->state &= ~state;



		if (!(freezer->state & CGROUP_FREEZING)) {

			if (was_freezing)

				atomic_dec(&system_freezing_cnt);

		freezer->state &= ~(CGROUP_FREEZING | CGROUP_FROZEN);

			freezer->state &= ~CGROUP_FROZEN;

			unfreeze_cgroup(freezer);

		}

	}

}



/**

 * freezer_change_state - change the freezing state of a cgroup_freezer
@@ -275,7 +290,7 @@ static void freezer_change_state(struct freezer *freezer, bool freeze) 
{

	/* update @freezer */

	spin_lock_irq(&freezer->lock);

	freezer_apply_state(freezer, freeze);

	freezer_apply_state(freezer, freeze, CGROUP_FREEZING_SELF);

	spin_unlock_irq(&freezer->lock);

}
@@ -295,6 +310,20 @@ static int freezer_write(struct cgroup *cgroup, struct cftype *cft, 
	return 0;

}



static u64 freezer_self_freezing_read(struct cgroup *cgroup, struct cftype *cft)

{

	struct freezer *freezer = cgroup_freezer(cgroup);



	return (bool)(freezer->state & CGROUP_FREEZING_SELF);

}



static u64 freezer_parent_freezing_read(struct cgroup *cgroup, struct cftype *cft)

{

	struct freezer *freezer = cgroup_freezer(cgroup);



	return (bool)(freezer->state & CGROUP_FREEZING_PARENT);

}



static struct cftype files[] = {

	{

		.name = "state",
@@ -302,6 +331,16 @@ static struct cftype files[] = { 
		.read_seq_string = freezer_read,

		.write_string = freezer_write,

	},

	{

		.name = "self_freezing",

		.flags = CFTYPE_NOT_ON_ROOT,

		.read_u64 = freezer_self_freezing_read,

	},

	{

		.name = "parent_freezing",

		.flags = CFTYPE_NOT_ON_ROOT,

		.read_u64 = freezer_parent_freezing_read,

	},

	{ }	/* terminate */

};