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

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Message-ID: <20251201105011.19386-2-phasta@kernel.org>
Date: Mon,  1 Dec 2025 11:50:04 +0100
From: Philipp Stanner <phasta@...nel.org>
To: Sumit Semwal <sumit.semwal@...aro.org>,
	Gustavo Padovan <gustavo@...ovan.org>,
	Christian König <christian.koenig@....com>,
	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>,
	Matthew Brost <matthew.brost@...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>
Cc: linux-media@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	amd-gfx@...ts.freedesktop.org,
	intel-gfx@...ts.freedesktop.org,
	intel-xe@...ts.freedesktop.org,
	Philipp Stanner <phasta@...nel.org>
Subject: [PATCH 0/6] dma-fence: Remove return code of dma_fence_signal() et al.

Tested this with dma_buf selftests and drm_sched tests.

Changes in v2:
  - Fix bug and don't turn the kernel into a smoking pile of ashes by
    not setting the signaled-bit…
  - Add functions (dma_fence_check_and_signal()) preserving the old
    behavior of dma_fence_signal() & Co. (Felix)
  - Use those new functions in amdkfd, xe, ttm and st-dma-fence.
  - Be a bit less aggressive and keep the git-diff smaller.
  - Add a patch using the flag-helper in Xe. (Matthew)

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

Removing the return code simplifies the API and makes it easier for me
to sit on top with Rust DmaFence.

Philipp Stanner (8):
  dma-buf/dma-fence: Add dma_fence_test_signaled_flag()
  dma-buf/dma-fence: Add dma_fence_check_and_signal()
  amd/amdkfd: Use dma_fence_check_and_signal()
  drm/xe: Use dma_fence_check_and_signal_locked()
  dma-buf: Don't misuse dma_fence_signal()
  drm/ttm: Use dma_fence_check_and_signal()
  dma-buf/dma-fence: Remove return code of signaling-functions
  drm/xe: Use dma_fence_test_signaled_flag()

 drivers/dma-buf/dma-fence.c                   | 100 +++++++++++-------
 drivers/dma-buf/st-dma-fence.c                |   4 +-
 drivers/gpu/drm/amd/amdkfd/kfd_process.c      |   6 +-
 .../gpu/drm/ttm/tests/ttm_bo_validate_test.c  |   2 +-
 drivers/gpu/drm/xe/xe_exec_queue.c            |   9 +-
 drivers/gpu/drm/xe/xe_hw_fence.c              |   4 +-
 drivers/gpu/drm/xe/xe_pt.c                    |   3 +-
 drivers/gpu/drm/xe/xe_sched_job.c             |   2 +-
 include/linux/dma-fence.h                     |  35 ++++--
 9 files changed, 102 insertions(+), 63 deletions(-)

-- 
2.49.0