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 <[email protected]>
---
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;
@@ -1017,12 +1018,13 @@ static int lme2510_powerup(struct dvb_usb_device *d, int onoff)
static u8 rbuf[1];
int ret, len = 3, rlen = 1;
- ret = mutex_lock_interruptible(&d->i2c_mutex);
+ if (mutex_lock_interruptible(&d->i2c_mutex) < 0)
+ return -EAGAIN;
if (onoff)
- ret |= lme2510_usb_talk(d, lnb_on, len, rbuf, rlen);
+ ret = lme2510_usb_talk(d, lnb_on, len, rbuf, rlen);
else
- ret |= lme2510_usb_talk(d, lnb_off, len, rbuf, rlen);
+ ret = lme2510_usb_talk(d, lnb_off, len, rbuf, rlen);
st->i2c_talk_onoff = 1;
--
1.7.1
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 <[email protected]>
> ---
> 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
On Sat, 2011-04-16 at 01:01 +0100, Malcolm Priestley wrote:
> 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 <[email protected]>
> > ---
> > 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.
>
I have added a patch to dvb-usb to return device errors to the demuxer
This patch may now be applied.
Tested by: Malcolm Priestley <[email protected]>
Regards
Malcolm