linux-kernel - Re: [PATCH 1/3] drm/nouveau: Prevent signaled fences in pending list

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Message-ID: <Z_0bOgTBkkRH9jib@cassiopeiae>
Date: Mon, 14 Apr 2025 16:27:06 +0200
From: Danilo Krummrich <dakr@...nel.org>
To: phasta@...nel.org
Cc: Christian König <christian.koenig@....com>,
	Lyude Paul <lyude@...hat.com>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Sabrina Dubroca <sd@...asysnail.net>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
	stable@...r.kernel.org
Subject: Re: [PATCH 1/3] drm/nouveau: Prevent signaled fences in pending list

On Mon, Apr 14, 2025 at 10:54:25AM +0200, Philipp Stanner wrote:
> @Danilo:
> We have now 2 possible solutions for the firing WARN_ON floating.
> 
> Version A (Christian)
> Check in nouveau_fence_context_kill() whether a fence is already
> signaled before setting an error.
> 
> Version B (Me)
> This patch series here. Make sure that in Nouveau, only
> nouveau_fence_signal() signals fences.
> 
> 
> Both should do the trick. Please share a maintainer-preference so I can
> move on here.

Thanks for working on this Philipp.

If you don't want to rework things entirely, A seems to be superior, since it
also catches the case when someone else would call dma_fence_is_signaled() on a
nouveau fence (which could happen at any time). This doesn't seem to be caught
by B, right?