Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 1/6] cgroup_freezer: fix freezer->state setting bug in freezer_change_state() | Date | Sat, 3 Sep 2011 03:27:45 +0900 |
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d02f52811d0e "cgroup_freezer: prepare for removal of TIF_FREEZE" moved setting of freezer->state into freezer_change_state(); unfortunately, while doing so, when it's beginning to freeze tasks, it sets the state to CGROUP_FROZEN instead of CGROUP_FREEZING ending up skipping the whole freezing state. Fix it.
-v2: Oleg pointed out that re-freezing FROZEN cgroup could increment system_freezing_cnt. Fixed.
-v3: Matt pointed out that setting CGROUP_FROZEN always invoked try_to_freeze_cgroup() regardless of the current state. Patch updated such that the actual freeze/thaw operations are always performed on state changes. This shouldn't make any difference unless something is broken.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Oleg Nesterov <oleg@redhat.com> Cc: Paul Menage <paul@paulmenage.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Matt Helsley <matthltc@us.ibm.com> --- kernel/cgroup_freezer.c | 14 +++++++------- 1 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 4e82525..56a457a 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -308,24 +308,24 @@ static int freezer_change_state(struct cgroup *cgroup, spin_lock_irq(&freezer->lock); update_if_frozen(cgroup, freezer); - if (goal_state == freezer->state) - goto out; - - freezer->state = goal_state; switch (goal_state) { case CGROUP_THAWED: - atomic_dec(&system_freezing_cnt); + if (freezer->state != CGROUP_THAWED) + atomic_dec(&system_freezing_cnt); + freezer->state = CGROUP_THAWED; unfreeze_cgroup(cgroup, freezer); break; case CGROUP_FROZEN: - atomic_inc(&system_freezing_cnt); + if (freezer->state == CGROUP_THAWED) + atomic_inc(&system_freezing_cnt); + freezer->state = CGROUP_FREEZING; retval = try_to_freeze_cgroup(cgroup, freezer); break; default: BUG(); } -out: + spin_unlock_irq(&freezer->lock); return retval; -- 1.7.6
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