[PATCH pm-freezer 1/4] cgroup_freezer: fix freezer->state setting bug in freezer_change_state()

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.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Menage <redacted>
Cc: "Rafael J. Wysocki" <redacted>
---
Rafael, these four patches fix the issues spotted by Oleg during
review of the freezer patchset.  Please apply them on pm-freezer once
Oleg acks them.  Thanks.

 kernel/cgroup_freezer.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: work/kernel/cgroup_freezer.c
===================================================================

--- 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;
 		atomic_inc(&system_freezing_cnt);
 		retval = try_to_freeze_cgroup(cgroup, freezer);
 		break;