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    SubjectRe: [PATCH] dvb-core: Fix potential mutex_unlock without mutex_lock in dvb_dvr_read
    From
    On Thu, Apr 30, 2009 at 5:48 PM, Andrew Morton
    <akpm@linux-foundation.org> wrote:
    > On Thu, 30 Apr 2009 22:42:06 +0100
    > Simon Arlott <simon@fire.lp0.eu> wrote:
    >
    >> >> diff --git a/drivers/media/dvb/dvb-core/dmxdev.c b/drivers/media/dvb/dvb-core/dmxdev.c
    >> >> index c35fbb8..d6d098a 100644
    >> >> --- a/drivers/media/dvb/dvb-core/dmxdev.c
    >> >> +++ b/drivers/media/dvb/dvb-core/dmxdev.c
    >> >> @@ -247,7 +247,7 @@ static ssize_t dvb_dvr_read(struct file *file, char __user *buf, size_t count,
    >> >>    int ret;
    >> >>
    >> >>    if (dmxdev->exit) {
    >> >> -          mutex_unlock(&dmxdev->mutex);
    >> >> +          //mutex_unlock(&dmxdev->mutex);
    >> >>            return -ENODEV;
    >> >>    }
    >> >
    >> > Is there any value in retaining all the commented-out lock operations,
    >> > or can we zap 'em?
    >>
    >> I'm assuming they should really be there - it's just not practical
    >> because the call to dvb_dmxdev_buffer_read is likely to block waiting
    >> for data.
    >
    > well..  such infomation is much better communicated via a nice comment,
    > rather than mystery-dead-code?

    I'm doing some review of the locking in dvb core as a result of a race
    condition I found earlier in the week. I'll take a look at this too
    when I get a few minutes.

    Devin

    --
    Devin J. Heitmueller
    http://www.devinheitmueller.com
    AIM: devinheitmueller
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