From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B080DC5B572 for ; Thu, 13 Aug 2026 09:46:59 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C71C510F265; Thu, 13 Aug 2026 09:46:58 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="MzQXAUGS"; dkim-atps=neutral Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 096FD10F265 for ; Thu, 13 Aug 2026 09:46:57 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id BBB4C409EC; Thu, 13 Aug 2026 09:46:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3AE061F000E9; Thu, 13 Aug 2026 09:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786614416; bh=059QHVrIU4FvtBb6TgfpigWxRmhKDqWqWuoeJnk7aNw=; h=From:To:Cc:Subject:Date; b=MzQXAUGS1M2kFHVbkZrfMu73e9Riko+OO7Anz2PQlooQ8ze42jYGyGr8M5w66wB+U cYmYJ8+cTfCnjIdPT2SSx9nyy0C1W3ZsY6VVULIaZskN/HUM1HHMKrWsHKp+DSD9du uDtFp12fOn6dMtZA5MydOWzjMlA7DE5HyLflnnGIHpmCh+bNODtzHawtO91mLiPMuS 6V7uc+/p7lhqqXn5xbXI0BwbcsycTVvk/LkOAP/vbEd+V3RiOArol9pgo4n/nIpTyn 0cDuTExK9yBD5w1rRtQlPp327OIAHqggarvUg6B56XapgniNCI2y0436fGczTVbMYF TNhJ1f234u4bg== From: Philipp Stanner To: Matthew Brost , Danilo Krummrich , Philipp Stanner , =?UTF-8?q?Christian=20K=C3=B6nig?= , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH] drm/sched: Lock drm_sched_entity_is_idle() Date: Thu, 13 Aug 2026 11:45:40 +0200 Message-ID: <20260813094539.2407911-2-phasta@kernel.org> X-Mailer: git-send-email 2.55.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" drm_sched_entity_is_idle() contains a badly documented memory barrier and an invalid lockless access to entity->stopped. Moreover, it also accesses entity->list which is at all other places protected by entity->lock. This function is in no way performance critical, so it is safer, more readable and more maintainable to take the spinlock. Add locking to drm_sched_entity_is_idle(). Signed-off-by: Philipp Stanner --- drivers/gpu/drm/scheduler/sched_entity.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index c51101ec70c1..2d941b2b2861 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -179,14 +179,18 @@ EXPORT_SYMBOL(drm_sched_entity_modify_sched); static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity) { - rmb(); /* for list_empty to work without lock */ + bool idle = false; + + spin_lock(&entity->lock); if (list_empty(&entity->list) || spsc_queue_count(&entity->job_queue) == 0 || entity->stopped) - return true; + idle = true; - return false; + spin_unlock(&entity->lock); + + return idle; } /** base-commit: c9a2c8ddcd65e96e7f095a87c0cc0b3211f740ea -- 2.55.0