On Sat, 2011-04-16 at 00:40 +0400, Alexey Khoroshilov wrote:
> There are a couple of places where mutex_unlock() is called even
> if mutex_lock_interruptible() failed. The patch fixes the issue.
>
> Found by Linux Driver Verification project (linuxtesting.org).
>
> Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
> ---
> drivers/media/dvb/dvb-usb/lmedm04.c | 12 +++++++-----
> 1 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/dvb/dvb-usb/lmedm04.c b/drivers/media/dvb/dvb-usb/lmedm04.c
> index f2db012..40907df 100644
> --- a/drivers/media/dvb/dvb-usb/lmedm04.c
> +++ b/drivers/media/dvb/dvb-usb/lmedm04.c
> @@ -591,9 +591,10 @@ static int lme2510_streaming_ctrl(struct dvb_usb_adapter *adap, int onoff)
> else {
> deb_info(1, "STM Steam Off");
> /* mutex is here only to avoid collision with I2C */
> - ret = mutex_lock_interruptible(&adap->dev->i2c_mutex);
> + if (mutex_lock_interruptible(&adap->dev->i2c_mutex) < 0)
> + return -EAGAIN;
>
> - ret |= lme2510_usb_talk(adap->dev, clear_reg_3,
> + ret = lme2510_usb_talk(adap->dev, clear_reg_3,
> sizeof(clear_reg_3), rbuf, rlen);
> st->stream_on = 0;
> st->i2c_talk_onoff = 1;
Unfortunately dvb-usb does not provide -EAGAIN on streaming_ctrl
stopping and returns 0 instead.
This code is deliberate even if the i2c_mutex is unlocked, the code must
be executed, and is protected by on going i2c_mutex by the usb_mutex.
This patch produces a intermittent stall on channel change.
Regards
Malcolm
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