[PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state()
Oleg Nesterov
oleg at redhat.com
Mon Aug 29 09:00:31 PDT 2011
On 08/29, Tejun Heo wrote:
>
> --- work.orig/kernel/cgroup_freezer.c
> +++ work/kernel/cgroup_freezer.c
> @@ -311,14 +311,14 @@ static int freezer_change_state(struct c
> if (goal_state == freezer->state)
> goto out;
>
> - freezer->state = goal_state;
> -
> switch (goal_state) {
> case CGROUP_THAWED:
> + freezer->state = CGROUP_THAWED;
> atomic_dec(&system_freezing_cnt);
> unfreeze_cgroup(cgroup, freezer);
> break;
> case CGROUP_FROZEN:
> + freezer->state = CGROUP_FREEZING;
At first glance, this is correct. I'll try to recheck.
But,
> atomic_inc(&system_freezing_cnt);
iiuc this becomes wrong... Suppose a user writes "FROZEN" twice,
before freezer->state becomes CGROUP_FROZEN.
I think we should actually fix the "goal_state == freezer->state"
check above.
Oleg.
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