Re: [PATCH 5.4 1/1] media: v4l2-mem2mem: Apply DST_QUEUE_OFF_BASE on MMAP buffers across ioctls

[Greg KH <greg@kroah.com>]

On Mon, Aug 08, 2022 at 03:41:30PM +0300, Ovidiu Panait wrote:
> From: Chen-Yu Tsai <wenst@chromium.org>
> 
> commit 8310ca94075e784bbb06593cd6c068ee6b6e4ca6 upstream.
> 
> DST_QUEUE_OFF_BASE is applied to offset/mem_offset on MMAP capture buffers
> only for the VIDIOC_QUERYBUF ioctl, while the userspace fields (including
> offset/mem_offset) are filled in for VIDIOC_{QUERY,PREPARE,Q,DQ}BUF
> ioctls. This leads to differences in the values presented to userspace.
> If userspace attempts to mmap the capture buffer directly using values
> from DQBUF, it will fail.
> 
> Move the code that applies the magic offset into a helper, and call
> that helper from all four ioctl entry points.
> 
> [hverkuil: drop unnecessary '= 0' in v4l2_m2m_querybuf() for ret]
> 
> Fixes: 7f98639def42 ("V4L/DVB: add memory-to-memory device helper framework for videobuf")
> Fixes: 908a0d7c588e ("[media] v4l: mem2mem: port to videobuf2")
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> [OP: backport to 5.4: adjusted return logic in v4l2_m2m_qbuf() to match the
> logic in the original commit: call v4l2_m2m_adjust_mem_offset() only if !ret
> and before the v4l2_m2m_try_schedule() call]
> Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
> ---
>  drivers/media/v4l2-core/v4l2-mem2mem.c | 60 ++++++++++++++++++++------
>  1 file changed, 46 insertions(+), 14 deletions(-)

Now queued up, thanks.

greg k-h