diff options
| author | Tejun Heo <tj@kernel.org> | 2012-11-09 17:12:30 (GMT) |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2012-11-09 17:12:30 (GMT) |
| commit | 5300a9b3482b6d9c32de6d5f4eaeab0fbafa70a8 (patch) | |
| tree | 775b078ce6af375ef2110e71a0f873f645d14671 /kernel/cgroup_freezer.c | |
| parent | a225218060fc8f10ed396c9c8187074697ad044d (diff) | |
| download | linux-5300a9b3482b6d9c32de6d5f4eaeab0fbafa70a8.tar.xz | |
cgroup_freezer: add ->post_create() and ->pre_destroy() and track online state
A cgroup is online and visible to iteration between ->post_create()
and ->pre_destroy(). This patch introduces CGROUP_FREEZER_ONLINE and
toggles it from the newly added freezer_post_create() and
freezer_pre_destroy() while holding freezer->lock such that a
cgroup_freezer can be reilably distinguished to be online. This will
be used by full hierarchy support.
ONLINE test is added to freezer_apply_state() but it currently doesn't
make any difference as freezer_write() can only be called for an
online cgroup.
Adjusting system_freezing_cnt on destruction is moved from
freezer_destroy() to the new freezer_pre_destroy() for consistency.
This patch doesn't introduce any noticeable 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>
Diffstat (limited to 'kernel/cgroup_freezer.c')
| -rw-r--r-- | kernel/cgroup_freezer.c | 42 |
1 files changed, 40 insertions, 2 deletions
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index b8ad93c..4f12d31 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -23,6 +23,7 @@ #include <linux/seq_file.h> enum freezer_state_flags { + CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */ 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 */ @@ -98,13 +99,45 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup) return &freezer->css; } -static void freezer_destroy(struct cgroup *cgroup) +/** + * freezer_post_create - commit creation of a freezer cgroup + * @cgroup: cgroup being created + * + * We're committing to creation of @cgroup. Mark it online. + */ +static void freezer_post_create(struct cgroup *cgroup) { struct freezer *freezer = cgroup_freezer(cgroup); + spin_lock_irq(&freezer->lock); + freezer->state |= CGROUP_FREEZER_ONLINE; + spin_unlock_irq(&freezer->lock); +} + +/** + * freezer_pre_destroy - initiate destruction of @cgroup + * @cgroup: cgroup being destroyed + * + * @cgroup is going away. Mark it dead and decrement system_freezing_count + * if it was holding one. + */ +static void freezer_pre_destroy(struct cgroup *cgroup) +{ + struct freezer *freezer = cgroup_freezer(cgroup); + + spin_lock_irq(&freezer->lock); + if (freezer->state & CGROUP_FREEZING) atomic_dec(&system_freezing_cnt); - kfree(freezer); + + freezer->state = 0; + + spin_unlock_irq(&freezer->lock); +} + +static void freezer_destroy(struct cgroup *cgroup) +{ + kfree(cgroup_freezer(cgroup)); } /* @@ -260,6 +293,9 @@ static void freezer_apply_state(struct freezer *freezer, bool freeze, /* also synchronizes against task migration, see freezer_attach() */ lockdep_assert_held(&freezer->lock); + if (!(freezer->state & CGROUP_FREEZER_ONLINE)) + return; + if (freeze) { if (!(freezer->state & CGROUP_FREEZING)) atomic_inc(&system_freezing_cnt); @@ -347,6 +383,8 @@ static struct cftype files[] = { struct cgroup_subsys freezer_subsys = { .name = "freezer", .create = freezer_create, + .post_create = freezer_post_create, + .pre_destroy = freezer_pre_destroy, .destroy = freezer_destroy, .subsys_id = freezer_subsys_id, .attach = freezer_attach, |