Re: [PATCH] media: videobuf2: forbid create_bufs/remove_bufs when legacy fileio is active

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 20.10.2025 09:11, Benjamin Gaignard wrote:
>
> Le 16/10/2025 à 13:11, Marek Szyprowski a écrit :
>> create_bufs and remove_bufs ioctl calls manipulate queue internal buffer
>> list, potentially overwriting some pointers used by the legacy fileio
>> access mode. Simply forbid those calls when fileio is active to protect
>> internal queue state between subsequent read/write calls.
>
> Hi Marek,
>
> I may be wrong but using fileio API and create/remove API at the same 
> time
> sound incorrect from application point of view, right ? If that not the
> case maybe we should also add a test in v4l2-compliance.

Definitely that's incorrect and v4l2-core must forbid such calls. The 
standard reqbufs/qbuf/dqbuf API is also forbidden. Extending 
v4l2-compliance tools is probably a good idea. I also wonder if its a 
good time to add a kernel option to completely disable legacy fileio 
access mode, as it is not really needed for most of the systems nowadays.

 > ...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland