Re: [PATCH 1/1] media: v4l: subdev: Make link validation safer

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 3/3/23 12:36, Tomi Valkeinen wrote:
> On 03/03/2023 13:30, Sakari Ailus wrote:
>> Hi Tomi,
>>
>> On Fri, Mar 03, 2023 at 10:41:27AM +0200, Tomi Valkeinen wrote:
>>> On 02/03/2023 22:22, Sakari Ailus wrote:
>>>> Link validation currently accesses invalid pointers if the link passed to it
>>>> is not between two sub-devices. This is of course a driver bug.
>>>>
>>>> Ignore the error but print a debug message, as this is how it used to work
>>>> previously.
>>>>
>>>> Fixes: a6b995ed03ff ("media: subdev: use streams in v4l2_subdev_link_validate()")
>>>> Reported-by: Hans de Goede <hdegoede@redhat.com>
>>>> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
>>>> ---
>>>> Hi Hans,
>>>>
>>>> Could you test this?
>>>>
>>>> The bug is of course in the ImgU driver and this reverts to the old
>>>> pre-streams behaviour. It silently fails instead of oopsing. The ImgU driver
>>>> needs to be fixed and I think we could make this return an error at the same
>>>> time. Right now I can't be sure the ImgU driver is the only one suffering
>>>> from this, but if so, it's likely to be broken anyway.
>>>
>>> Maybe it should be at least a warn? How do we catch other broken drivers
>>> otherwise?
>>
>> The purpose of this patch is just to restore the old behaviour, and merge
>> it as a fix to v6.3 (via Cc'ing stable). I agree this should be made an
>> error but I'd like that change to be present in the media tree for some
>> time first.
> 
> I meant that keep it returning 0 (no error), but instead of a debug print, use pr_warn. Or maybe pr_warn_once for now.

Switching to pr_warn_once() sounds reasonable to me.

I'll try to give this a test-run sometime next week.

Regards,

Hans