4.14-stable patches

[thirdparty/kernel/stable-queue.git] / releases / 2.6.32.27 / backlight-grab-ops_lock-before-testing-bd-ops.patch

From d1d73578e053b981c3611e5a211534290d24a5eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Date: Wed, 24 Nov 2010 12:57:14 -0800
Subject: backlight: grab ops_lock before testing bd->ops
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From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>

commit d1d73578e053b981c3611e5a211534290d24a5eb upstream.

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.

Fixes a problem added by c835ee7f4154992e6 ("backlight: Add suspend/resume
support to the backlight core") in Jan 2009.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Richard Purdie <rpurdie@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/video/backlight/backlight.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -196,12 +196,12 @@ static int backlight_suspend(struct devi
 {
 	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;
 }
@@ -210,12 +210,12 @@ static int backlight_resume(struct devic
 {
 	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;
 }