Re: Re: [PATCH 5/7] media: cedrus: h265: Add a couple of error checks
From: Jernej Škrabec
Date: Tue Jul 12 2022 - 17:25:22 EST
Dne ponedeljek, 11. julij 2022 ob 23:31:11 CEST je Ezequiel Garcia napisal(a):
> On Mon, Jun 20, 2022 at 07:55:15PM +0200, Jernej Skrabec wrote:
> > Now that we have infrastructure for reporting errors, let's add two
> > checks, which will make sure slice can be actually decoded.
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> > ---
> > drivers/staging/media/sunxi/cedrus/cedrus_h265.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c index
> > cfde4ccf6011..99020b9f9ff8 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> Now that you've allowed setup to fail, I would suggest
> to have some documentation/comments on struct cedrus_dec_ops,
> to set the expectation/rules for each ops, including the
> call paths for each operation, which of them are allowed to sleep,
Documentation can be always added, but it should be separate patch.
> > @@ -435,9 +435,17 @@ static int cedrus_h265_setup(struct cedrus_ctx *ctx,
> > struct cedrus_run *run)>
> > * instead of start of slice data. Padding is 8 bits at most (one
> > set to 1 and * at most seven bits set to 0), so we have to
> > only one byte before slice data. */
> > +
> > + if (slice_params->data_byte_offset == 0)
> > + return -EOPNOTSUPP;
> > +
> AFAICS, cedrus_h265_setup is called from .device_run.
> We've been discussing control validation before, and I think the
> ideal place to do that is v4l2_ctrl_ops.s_ctrl, if that's
> at all possible.
Yeah, this particular check can be moved to s_ctrl handler.
> Driver's mem2mem device_run are executed in the context
> of a work_struct and the failure won't really get reported
> up the stack.
Well, at least there will be a notice in dmesg. Not ideal, I know.
> > padding = (u8 *)vb2_plane_vaddr(&run->src->vb2_buf, 0) +
> > slice_params->data_byte_offset - 1;
> > + /* at least one bit must be set in that byte */
> > + if (*padding == 0)
> > + return -EINVAL;
> > +
> Maybe this is something to check at cedrus_buf_prepare(),
> when the buffer is queued?
I don't think so. This check is HEVC specific, but cedrus_buf_prepare() is not
and we need to have slice control ready, which I'm not sure is the case for
> > for (count = 0; count < 8; count++)
> > if (*padding & (1 << count))
> > break;
> > --
> > 2.36.1