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Subject[34-longterm 092/209] backlight: grab ops_lock before testing bd->ops
Date
From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

=====================================================================
| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|
=====================================================================
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: Paul Gortmaker <paul.gortmaker@windriver.com>
---
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;
}
--
1.7.4.4
--
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