linux-kernel - [PATCH RFC v1 2/3] Fix hibernation restore hang in freeze

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Message-Id: <1392774729-3235-3-git-send-email-sebastian.capella@linaro.org>
Date:	Tue, 18 Feb 2014 17:52:08 -0800
From:	Sebastian Capella <sebastian.capella@...aro.org>
To:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linaro-kernel@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org
Cc:	Sebastian Capella <sebastian.capella@...aro.org>,
	Russ Dill <Russ.Dill@...com>,
	Ming Lei <ming.lei@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH RFC v1 2/3] Fix hibernation restore hang in freeze_processes

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>
Cc: Russ Dill <Russ.Dill@...com>
Cc: Ming Lei <ming.lei@...onical.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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 eb8fb94..e2b51f8 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -1541,6 +1541,7 @@ 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;
-- 
1.7.9.5

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