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[34.16.154.73]) by smtp.gmail.com with UTF8SMTPSA id 41be03b00d2f7-bf6a1306a8bsm2381263a12.18.2025.12.04.09.45.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Dec 2025 09:45:49 -0800 (PST) From: Chia-I Wu To: Boris Brezillon , Steven Price , Liviu Dudau , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Grant Likely , Heiko Stuebner , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, tvrtko.ursulin@igalia.com Subject: [PATCH v2] drm/panthor: fix for dma-fence safe access rules Date: Thu, 4 Dec 2025 09:45:45 -0800 Message-ID: <20251204174545.399059-1-olvaffe@gmail.com> X-Mailer: git-send-email 2.52.0.223.gf5cc29aaa4-goog 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" Commit 506aa8b02a8d6 ("dma-fence: Add safe access helpers and document the rules") details the dma-fence safe access rules. The most common culprit is that drm_sched_fence_get_timeline_name may race with group_free_queue. Signed-off-by: Chia-I Wu Reviewed-by: Boris Brezillon Reviewed-by: Liviu Dudau Reviewed-by: Steven Price --- v2: collect R-bs and drop misleading Fixes: tag --- drivers/gpu/drm/panthor/panthor_sched.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/pant= hor/panthor_sched.c index 33b9ef537e359..a8b1347e4da71 100644 --- a/drivers/gpu/drm/panthor/panthor_sched.c +++ b/drivers/gpu/drm/panthor/panthor_sched.c @@ -23,6 +23,7 @@ #include #include #include +#include =20 #include "panthor_devfreq.h" #include "panthor_device.h" @@ -923,6 +924,9 @@ static void group_release_work(struct work_struct *work) release_work); u32 i; =20 + /* dma-fences may still be accessing group->queues under rcu lock. */ + synchronize_rcu(); + for (i =3D 0; i < group->queue_count; i++) group_free_queue(group, group->queues[i]); =20 --=20 2.52.0.223.gf5cc29aaa4-goog