linux-kernel - Re: [PATCH v3 1/5] media: mc: add manual request completion

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2e4ef756-a8cf-415c-99ba-a3d72f3288e1@jjverkuil.nl>
Date: Mon, 9 Jun 2025 11:49:08 +0200
From: Hans Verkuil <hans@...erkuil.nl>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>,
 Nicolas Dufresne <nicolas.dufresne@...labora.com>
Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil
 <hverkuil@...all.nl>, Tiffany Lin <tiffany.lin@...iatek.com>,
 Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
 Yunfei Dong <yunfei.dong@...iatek.com>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-mediatek@...ts.infradead.org, kernel@...labora.com,
 linux-media@...r.kernel.org,
 Sebastian Fricke <sebastian.fricke@...labora.com>
Subject: Re: [PATCH v3 1/5] media: mc: add manual request completion

On 09/06/2025 11:42, Sakari Ailus wrote:
> Hi,
> 
> On Thu, Jun 05, 2025 at 08:41:45AM -0400, Nicolas Dufresne wrote:
>> Hi Hans, Sakari,
>>
>> Le jeudi 05 juin 2025 à 09:48 +0000, Sakari Ailus a écrit :
>>>> It's not user-triggerable, if this happens, then it is a driver bug.
>>>
>>> If there is a driver bug, it could well be user-triggerable, wouldn't it?
>>> Testing may not uncover all such cases.
>>
>> You are both right, if the driver is not used, the warning will never
>> trigger. I was worried of the hit of a thread safe ONCE implementation,
>> but WARN_ONCE is simply not, it can warn few time before it stops if
>> called from multiple CPUs at the same time. In that specific function,
>> I can move all the checks inside the lock to make it truly once.
>>
>> Now its up to you, I don't have strong preference. These are driver errors,
>> and usually quite critical. They are not bug_on simply because we have a
>> crash free resolution, but its probably not functional anymore.
> 
> I'd prefer _ONCE variants, I wonder what Hans thinks.
> 

I have no particular preference.

Regards,

	Hans