Dne petek, 19. avgust 2022 ob 17:39:25 CEST je Nicolas Dufresne napisal(a):
> Le vendredi 19 août 2022 à 06:16 +0200, Jernej Škrabec a écrit :
> > Dne četrtek, 18. avgust 2022 ob 22:33:08 CEST je Nicolas Dufresne
napisal(a):
> > > From: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> > >
> > > The busy status bit may never de-assert if number of programmed skip
> > > bits is incorrect, resulting in a kernel hang because the bit is polled
> > > endlessly in the code. Fix it by adding timeout for the bit-polling.
> > > This problem is reproducible by setting the data_bit_offset field of
> > > the HEVC slice params to a wrong value by userspace.
> > >
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Reported-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
> > > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> > > Signed-off-by: Nicolas Dufresne <nicolas.dufresne@xxxxxxxxxxxxx>
> >
> > Fixes tag would be nice.
> >
> > > ---
> > >
> > > drivers/staging/media/sunxi/cedrus/cedrus_h265.c | 6 ++++--
> > > 1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > > b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c index
> > > f703c585d91c5..f0bc118021b0a 100644
> > > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > > @@ -227,6 +227,7 @@ static void cedrus_h265_pred_weight_write(struct
> > > cedrus_dev *dev, static void cedrus_h265_skip_bits(struct cedrus_dev
> > > *dev,
> > > int num) {
> > >
> > > int count = 0;
> > >
> > > + u32 reg;
> > >
> > > while (count < num) {
> > >
> > > int tmp = min(num - count, 32);
> > >
> > > @@ -234,8 +235,9 @@ static void cedrus_h265_skip_bits(struct cedrus_dev
> > > *dev, int num) cedrus_write(dev, VE_DEC_H265_TRIGGER,
> > >
> > > VE_DEC_H265_TRIGGER_FLUSH_BITS |
> > > VE_DEC_H265_TRIGGER_TYPE_N_BITS(tmp));
> > >
> > > - while (cedrus_read(dev, VE_DEC_H265_STATUS) &
> > > VE_DEC_H265_STATUS_VLD_BUSY) - udelay(1);
> > > +
> > > + if (cedrus_wait_for(dev, VE_DEC_H265_STATUS,
> > > VE_DEC_H265_STATUS_VLD_BUSY)) +
> >
> > dev_err_ratelimited(dev->dev, "timed out
> >
> > > waiting to skip bits\n");
> >
> > Reporting issue is nice, but better would be to propagate error, since
> > there is no way to properly decode this slice if above code block fails.
> This mimic what was already there, mind if we do that later ? The
> propagation is doing to be a lot more intrusive.
Since backporting fixes before 6.0 isn't priority, viability for backpporting
isn't that important. You would only need to return 0 or -ETIMEDOUT and check
for error in only one location. That doesn't sound very intrusive for me.
Best regards,
Jernej
>
> > Best regards,
> > Jernej
> >
> > > count += tmp;
> > >
> > > }
