linux-kernel - Re: [PATCH 0/6] dma-fence: Remove return code of dma_fence

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Message-ID: <aSc4XnSv/mQ8A9cI@lstrano-desk.jf.intel.com>
Date: Wed, 26 Nov 2025 09:26:54 -0800
From: Matthew Brost <matthew.brost@...el.com>
To: <phasta@...nel.org>
CC: Christian König <christian.koenig@....com>, "Sumit
 Semwal" <sumit.semwal@...aro.org>, Gustavo Padovan <gustavo@...ovan.org>,
	Felix Kuehling <Felix.Kuehling@....com>, Alex Deucher
	<alexander.deucher@....com>, David Airlie <airlied@...il.com>, Simona Vetter
	<simona@...ll.ch>, Jani Nikula <jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>, Huang Rui <ray.huang@....com>,
	"Matthew Auld" <matthew.auld@...el.com>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, Lucas De Marchi
	<lucas.demarchi@...el.com>, Thomas Hellström
	<thomas.hellstrom@...ux.intel.com>, <linux-media@...r.kernel.org>,
	<dri-devel@...ts.freedesktop.org>, <linaro-mm-sig@...ts.linaro.org>,
	<linux-kernel@...r.kernel.org>, <amd-gfx@...ts.freedesktop.org>,
	<intel-gfx@...ts.freedesktop.org>, <intel-xe@...ts.freedesktop.org>,
	<rust-for-linux@...r.kernel.org>
Subject: Re: [PATCH 0/6] dma-fence: Remove return code of dma_fence_signal()
 et al.

On Wed, Nov 26, 2025 at 03:09:26PM +0100, Philipp Stanner wrote:
> On Wed, 2025-11-26 at 15:02 +0100, Christian König wrote:
> > On 11/26/25 14:19, Philipp Stanner wrote:
> > > Barely anyone uses dma_fence_signal()'s (and similar functions') return
> > > code. Checking it is pretty much useless anyways, because what are you
> > > going to do if a fence was already signal it? Unsignal it and signal it
> > > again? ;p
> > 
> > Reviewed-by: Christian König <christian.koenig@....com> for the entire series.
> > 
> > Please push to drm-misc-next or leave me a note when I should pick it up.
> 
> Thx! I can push it. Let's wait a while to see if some of the other
> folks have sth to say.
> 

I think you have a small bug in patch #1 [1]. Also Intel's CI [2] is
complaining, it would nice to figure that out too + get a clean(ish) run
ahead of merging.

Matt

[1] https://patchwork.freedesktop.org/patch/690505/?series=158108&rev=1#comment_1268421
[2] https://patchwork.freedesktop.org/series/158108/

> > 
> > > Removing the return code simplifies the API and makes it easier for me
> > > to sit on top with Rust DmaFence.
> > 
> > BTW, I have an rb for embedding the lock and I'm now writing test cases.
> > 
> > When that is done you should be able to base the Rust DmaFence abstraction on that as well.
> 
> Yeah, thank you, that will actually help since I was in the process of
> solving the same life time issues in Rust.
> 
> I will give your series a review ~tomorrow, too. Or should I wait for
> v4 with the tests?
> 
> P.
> 
> > 
> > Regards,
> > Christian.
> > 
> > > 
> > > Philipp Stanner (6):
> > >   dma-buf/dma-fence: Add dma_fence_test_signaled_flag()
> > >   amd/amdkfd: Ignore return code of dma_fence_signal()
> > >   drm/gpu/xe: Ignore dma_fenc_signal() return code
> > >   dma-buf: Don't misuse dma_fence_signal()
> > >   drm/ttm: Remove return check of dma_fence_signal()
> > >   dma-buf/dma-fence: Remove return code of signaling-functions
> > > 
> > >  drivers/dma-buf/dma-fence.c                   | 59 ++++++-------------
> > >  drivers/dma-buf/st-dma-fence.c                |  7 +--
> > >  drivers/gpu/drm/amd/amdkfd/kfd_process.c      |  5 +-
> > >  .../gpu/drm/ttm/tests/ttm_bo_validate_test.c  |  3 +-
> > >  drivers/gpu/drm/xe/xe_hw_fence.c              |  5 +-
> > >  include/linux/dma-fence.h                     | 33 ++++++++---
> > >  6 files changed, 53 insertions(+), 59 deletions(-)
> > > 
> > 
>