Re: kern/58745 (nouveau triggered assert in linux_dma_fence.c)

["Taylor R Campbell via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/58745; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
	gnats-admin%netbsd.org@localhost, mrg%eterna23.net@localhost
Subject: Re: kern/58745 (nouveau triggered assert in linux_dma_fence.c)
Date: Sat, 12 Oct 2024 02:29:12 +0000

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 Attached patch works around it.  On the fence about whether to commit
 this (and introduce another local diff) or just relax the assertion.
 
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 # HG changeset patch
 # User Taylor R Campbell <riastradh%NetBSD.org@localhost>
 # Date 1728700032 0
 #      Sat Oct 12 02:27:12 2024 +0000
 # Branch trunk
 # Node ID 8465cbb178fcac2a01a66c33646eb41f7b497283
 # Parent  94b69b01d60e6b02d6aefbbb562c511991aba09f
 # EXP-Topic riastradh-pr58745-nvfencechanerr
 nouveau: Don't set dma fence error if already signaled.
 
 This happens asynchronously on hardware error.  Upstream Linux trips
 WARN_ON in this case; our dma_fence_set_error trips KASSERT instead.
 We could maybe switch dma_fence_set_error to use WARN_ON too but it's
 probably better not to take this path anyway -- this assertion trips
 on logic that is incoherent, if not outright wrong.
 
 PR kern/58745: nouveau triggered assert in linux_dma_fence.c
 
 diff -r 94b69b01d60e -r 8465cbb178fc sys/external/bsd/drm2/dist/drm/nouveau=
 /nouveau_fence.c
 --- a/sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.c	Thu Oct 10 21:=
 42:24 2024 +0000
 +++ b/sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.c	Sat Oct 12 02:=
 27:12 2024 +0000
 @@ -102,7 +102,7 @@ nouveau_fence_context_kill(struct nouvea
  	while (!list_empty(&fctx->pending)) {
  		fence =3D list_entry(fctx->pending.next, typeof(*fence), head);
 =20
 -		if (error)
 +		if (error && !dma_fence_is_signaled_locked(&fence->base))
  			dma_fence_set_error(&fence->base, error);
 =20
  		if (nouveau_fence_signal(fence))
 
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