From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 B9DEE3B27D1 for ; Thu, 13 Aug 2026 09:46:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786614417; cv=none; b=s9HQKzUAYfyW7IdsNw66tci01iw1m+mbluLDLpbsh+/PApu4wujYblmzOKPvJ+jzHqytXmF19Et1MAbffn3cHWpex/SY+TNVRG/rywKK/caurRy9bYI/DYsD+elt2mOTdBNgtoeKGOw/eBcaPL0/kcwiDOwb7cScTNQoftKqcK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786614417; c=relaxed/simple; bh=5nfvL6oqTb5ccNUG29bRHjrcb3h8C+i7+qZh8Tih7ts=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=uS1A8Atsmx3KGn5tPgWX8ficjr4AJAFKesg3ivSD+lNLebs4k6KYG4KYiRbnBpdvJvXcimXvD+na7FpgFe2qFU5bedNh8pvauj3YBj/dTs/7Si4CkzFOE3PaniR9SPM3+vMklTQZmf6Bhu5LjM2jjhuKn6Z+js1u4N+ha770cBc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MzQXAUGS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MzQXAUGS" 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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