linux-kernel - [PATCH 3.13 160/172] PM / hibernate: Fix restore hang in freeze

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Message-Id: <20140304200304.835191837@linuxfoundation.org>
Date:	Tue,  4 Mar 2014 12:04:04 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Sebastian Capella <sebastian.capella@...aro.org>,
	Ming Lei <ming.lei@...onical.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.13 160/172] PM / hibernate: Fix restore hang in freeze_processes()

3.13-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: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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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