linux-kernel - [PATCH 3.8 65/81] PM / hibernate: Fix restore hang in freeze

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Message-Id: <1395767794-5012-66-git-send-email-kamal@canonical.com>
Date:	Tue, 25 Mar 2014 10:16:18 -0700
From:	Kamal Mostafa <kamal@...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>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.8 65/81] PM / hibernate: Fix restore hang in freeze_processes()

3.8.13.20 -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: Kamal Mostafa <kamal@...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 b392b35..abb2054 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -1413,6 +1413,7 @@ static int fw_pm_notify(struct notifier_block *notify_block,
 	switch (mode) {
 	case PM_HIBERNATION_PREPARE:
 	case PM_SUSPEND_PREPARE:
+	case PM_RESTORE_PREPARE:
 		device_cache_fw_images();
 		break;
 
-- 
1.8.3.2

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