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SubjectRe: [PATCH] backlight: grab ops_lock before testing bd->ops
Hello,

On Mon, Nov 22, 2010 at 09:59:07AM +0000, Richard Purdie wrote:
> On Mon, 2010-11-22 at 10:43 +0100, Uwe Kleine-König wrote:
> > 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@pengutronix.de>
>
> Acked-by: Richard Purdie <rpurdie@linux.intel.com>
The problem was introduced by c835ee7f4154992e6cf0674d7ee136f5d36247a4
(that is in 2.6.29-rc1). Is this relevant for stable?

Best regards
Uwe

> > ---
> > 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;
> > }
>
>
>

--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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