[PATCH 3.13 160/172] PM / hibernate: Fix restore hang in freeze_processes()

From: Greg Kroah-Hartman
Date: Tue Mar 04 2014 - 15:49:23 EST


3.13-stable review patch. If anyone has any objections, please let me know.

------------------

From: Sebastian Capella <sebastian.capella@xxxxxxxxxx>

commit f8d5b9e9e5372f0deb7bc1ab1088a9b60b0a793d upstream.

During restore, pm_notifier chain are called with
PM_RESTORE_PREPARE. The firmware_class driver handler
fw_pm_notify does not have a handler for this. As a result,
it keeps a reader on the kmod.c umhelper_sem. During
freeze_processes, the call to __usermodehelper_disable tries to
take a write lock on this semaphore and hangs waiting.

Signed-off-by: Sebastian Capella <sebastian.capella@xxxxxxxxxx>
Acked-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/base/firmware_class.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -1541,6 +1541,7 @@ static int fw_pm_notify(struct notifier_
switch (mode) {
case PM_HIBERNATION_PREPARE:
case PM_SUSPEND_PREPARE:
+ case PM_RESTORE_PREPARE:
kill_requests_without_uevent();
device_cache_fw_images();
break;


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