From mboxrd@z Thu Jan 1 00:00:00 1970 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 D72C233E352; Fri, 31 Oct 2025 12:00:38 +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=1761912038; cv=none; b=pRsStxIZJW0fuuvU58QYCN9vjHLfqZRhaNxQXxmbahE7kVl8z49VhwYW2Qx0B9Yb2Eba69htOEEWDCoOV8zkKmqz8GDD+Xi+1GbInLvLqdCr9ktX1hZ7NqS4sSqC0vDihdOLECMX7/cjndkOb42THc/qAp/MQbKG94M1Q5RXN+A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761912038; c=relaxed/simple; bh=5Y2K69DPuTxufr2/30uL7COrThaw9oWJXaibDgLkv3M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TFJRfG9zAQeLRidrG57NvcOnBjgHwFPgZceeDNFh/NpGYSFXIpBaEKGKriZM3AF3xD2ECm/QNCLknaFowz8W9XWhBH6AmWC9ZEj7OkTS4UXkzJ7EbIen8Hc+6bB6bSyOyJMsieQRnST0lHxyJ62Aqmjb2SX+PHAzBAEfwDKr0vw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=vEUTepPw; 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="vEUTepPw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B5CFC4CEFB; Fri, 31 Oct 2025 12:00:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761912038; bh=5Y2K69DPuTxufr2/30uL7COrThaw9oWJXaibDgLkv3M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vEUTepPwhkQmpxfK8CEXqfwhXgYhIcPm7nNen+UsWtqrisuiz5Peyp5WXllkTGtLs J4Jc4g7fyHIII5OnqUtgmB/NFzNUsXHDAJuNR0PYwGMIiEogZz62hWd+xR42vFW02A HJbM29Zgy8cdeC3XtjFVcNCzum2H87VpT3TK/vA+7obu12IZgwJVD1mlqt8KyVisXJ wje2R340p3eZNFfpUfDsVdYqtRJzxgY65Me5QsT5tkygf3+zUxV+2CTHMHybHAK53V vMvkJNaaC4lwGb8NO1npdlC1mGOGwAntkZBZ0+BuGwum2RuqSrQvYxaMjuuRzV+REP Dbk+q+MujeA/g== From: Philipp Stanner To: David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Jonathan Corbet Cc: dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Philipp Stanner Subject: [PATCH 2/2] drm/todo: Add entry for unlocked drm/sched rq readers Date: Fri, 31 Oct 2025 13:00:15 +0100 Message-ID: <20251031120014.248416-4-phasta@kernel.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20251031120014.248416-2-phasta@kernel.org> References: <20251031120014.248416-2-phasta@kernel.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Runqueues are currently almost everywhere being read unlocked in drm/sched. At XDC 2025, the assembled developers were unsure whether that's legal and whether it can be fixed. Someone should find out. Add a todo entry for the unlocked runqueue reader problem. Signed-off-by: Philipp Stanner --- Documentation/gpu/todo.rst | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 835e799ddfe2..7d7e9e3741e9 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -909,6 +909,20 @@ Contact: Christian König Level: Advanced +Add locking for runqueues +------------------------- + +There is an old FIXME by Sima in include/drm/gpu_scheduler.h. It details 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 real, that should +probably be locked!). Check whether it's possible to add locks everywhere, and +do so if yes. + +Contact: Philipp Stanner + +Level: Intermediate + Outside DRM =========== -- 2.49.0