linux-kernel - [PATCH 3.11 116/131] PM / hibernate: Fix restore hang in freeze

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Date:	Wed,  5 Mar 2014 14:24:00 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Sebastian Capella <sebastian.capella@...aro.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.11 116/131] PM / hibernate: Fix restore hang in freeze_processes()

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

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

From: Sebastian Capella <sebastian.capella@...aro.org>

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@...aro.org>
Acked-by: Ming Lei <ming.lei@...onical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.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

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