linux-kernel - [PATCH] backlight: grab ops

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Message-Id: <1290418989-27653-1-git-send-email-u.kleine-koenig@pengutronix.de>
Date:	Mon, 22 Nov 2010 10:43:09 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Richard Purdie <rpurdie@...ys.net>
Cc:	linux-kernel@...r.kernel.org, kernel@...gutronix.de
Subject: [PATCH] backlight: grab ops_lock before testing bd->ops

According to the comment describing ops_lock in the definition of
struct backlight_device and when comparing with other functions in
backlight.c the mutex must be hold when checking ops to be non-NULL.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 drivers/video/backlight/backlight.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index e207810..0870329 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -197,12 +197,12 @@ static int backlight_suspend(struct device *dev, pm_message_t state)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 
-	if (bd->ops->options & BL_CORE_SUSPENDRESUME) {
-		mutex_lock(&bd->ops_lock);
+	mutex_lock(&bd->ops_lock);
+	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 		bd->props.state |= BL_CORE_SUSPENDED;
 		backlight_update_status(bd);
-		mutex_unlock(&bd->ops_lock);
 	}
+	mutex_unlock(&bd->ops_lock);
 
 	return 0;
 }
@@ -211,12 +211,12 @@ static int backlight_resume(struct device *dev)
 {
 	struct backlight_device *bd = to_backlight_device(dev);
 
-	if (bd->ops->options & BL_CORE_SUSPENDRESUME) {
-		mutex_lock(&bd->ops_lock);
+	mutex_lock(&bd->ops_lock);
+	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
 		bd->props.state &= ~BL_CORE_SUSPENDED;
 		backlight_update_status(bd);
-		mutex_unlock(&bd->ops_lock);
 	}
+	mutex_unlock(&bd->ops_lock);
 
 	return 0;
 }
-- 
1.7.2.3

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