From nobody Sat Feb 7 18:46:34 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A3FD267714; Thu, 23 Oct 2025 14:30:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761229851; cv=none; b=jYBHtiO/Zgsg3dUR5iID1kpCRo8jBIy26toCAc12BqE59c6rCtTV93PkJN2x5TR+wakBrmlZA1Uln3JWuO61UbIqaJDLKMRHYSOK+HuDyshgAFcSy6Xm5KF7C7tXkNEJOCq5p4E/1k763OwJh8oThRCJIyCiwTHpfV53yRDWVYA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761229851; c=relaxed/simple; bh=LbOep4u6dGmMx3E06SFB+2sU4wVXqcLPOLAVpCN4zb8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Zs4CDaP72j3RjAgsX57+lpSvMQ0pMRT3bf+MQ4WGd0nrxYtM7axeZOQhPH06WhK3Dcw0AGtNAWATY94MRrhdS7ZuJdjXu+Nj8mNu0kPRxMKkHGrFVZTIj7JNUfooAiQ05KzNY6Twb9/NsV/P+pLPHccEY8gczrZG9jXCplb7VCQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jxQNZnH1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jxQNZnH1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66FF1C116D0; Thu, 23 Oct 2025 14:30:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761229850; bh=LbOep4u6dGmMx3E06SFB+2sU4wVXqcLPOLAVpCN4zb8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jxQNZnH1Iuq3NQom6PZ+X6LwQYE4XRNMIYyz/q4+d+zNT29CuV0rtNMiE7kJGLTSp 58GHiiXK8Dyw74JqZpPaGVsAzD8SReMcho77UlDJ3AmggupP63+XBuUCFGja1pIouk qFbzWbAcnbzagGrd1XNtCbdR2pAAyP+YEe7HHIOAR+FfLCArmDC9aaEOYrqz2XBqZY 1r/8FUTqCjUYqhkjIIBRC2pvALZRoQAfcj4QyDo9XUHHgAvRnmQxQY4R0LeAM46uqK weFuvTqGxYrV8QXS9jylqEQ8veBwmtWYX0TUm6SzdN8TGjXvGp1LjblqHmzrWyBO2I ci9Qk5MX8T5WQ== From: Philipp Stanner To: Matthew Brost , Danilo Krummrich , Philipp Stanner , =?UTF-8?q?Christian=20K=C3=B6nig?= , David Airlie , Simona Vetter , Tvrtko Ursulin Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org Subject: [PATCH v2 4/4] drm/sched: Add TODO entry for missing runqueue locks Date: Thu, 23 Oct 2025 16:30:31 +0200 Message-ID: <20251023143031.149496-6-phasta@kernel.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251023143031.149496-2-phasta@kernel.org> References: <20251023143031.149496-2-phasta@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" struct drm_sched_rq is not being locked at many places throughout the scheduler, at least for readers. This was documented in a FIXME added in: commit 981b04d96856 ("drm/sched: improve docs around drm_sched_entity") Add a TODO entry for that problem. Signed-off-by: Philipp Stanner --- drivers/gpu/drm/scheduler/TODO | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/gpu/drm/scheduler/TODO b/drivers/gpu/drm/scheduler/TODO index 713dd62c58da..263ce2deb69a 100644 --- a/drivers/gpu/drm/scheduler/TODO +++ b/drivers/gpu/drm/scheduler/TODO @@ -36,3 +36,16 @@ 3. Port a driver as first user. 3. Document the new alternative in the docu of deprecated drm_sched_resubmit_jobs(). + +* Unlocked readers for runqueues + - Difficulty: medium + - Contact: Philipp Stanner + - Description: + There is an old FIXME by Sima in include/drm/gpu_scheduler.h. It detai= ls + that struct drm_sched_rq is read at many places without any locks, not= even + with a READ_ONCE. At XDC 2025 no one could really tell why that is the= case, + whether locks are needed and whether they could be added. (But for rea= l, + that should probably be locked!). + - Tasks: + 1. Check whether locks for runqueue readers can be added. + 2. If yes, add the locks. --=20 2.49.0