[3.11.y.z extended stable] Patch "PM / hibernate: Fix restore hang in freeze_processes()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    PM / hibernate: Fix restore hang in freeze_processes()

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 2fa78d9f3a7340819b9b347b5ccd2321d5401fdd Mon Sep 17 00:00:00 2001
From: Sebastian Capella <sebastian.capella at linaro.org>
Date: Tue, 18 Feb 2014 17:52:08 -0800
Subject: PM / hibernate: Fix restore hang in freeze_processes()

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 at linaro.org>
Acked-by: Ming Lei <ming.lei at canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/base/firmware_class.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index c8dac74..8933926 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -1532,6 +1532,7 @@ static int fw_pm_notify(struct notifier_block *notify_block,
 	switch (mode) {
 	case PM_HIBERNATION_PREPARE:
 	case PM_SUSPEND_PREPARE:
+	case PM_RESTORE_PREPARE:
 		kill_requests_without_uevent();
 		device_cache_fw_images();
 		break;
--
1.9.0