FAILED: patch "[PATCH] drm/vc4: Shut down BO cache timer before teardown" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 6273dd3ffb54ec581855b82ae77331b66028249c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026072902-wanted-profusely-73da@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6273dd3ffb54ec581855b82ae77331b66028249c Mon Sep 17 00:00:00 2001
From: Linmao Li <lilinmao@kylinos.cn>
Date: Mon, 20 Jul 2026 16:44:26 +0800
Subject: [PATCH] drm/vc4: Shut down BO cache timer before teardown
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The BO cache timer callback schedules time_work, and time_work can rearm
the timer through vc4_bo_cache_free_old().

vc4_bo_cache_destroy() deletes the timer and then cancels the work, which
does not break that cycle: the work being cancelled can rearm the timer,
and the timer then queues work again after teardown.

Use timer_shutdown_sync() instead, so the timer cannot be rearmed and the
cycle ends with cancel_work_sync().

Fixes: c826a6e10644 ("drm/vc4: Add a BO cache.")
Cc: stable@vger.kernel.org
Signed-off-by: Linmao Li <lilinmao@kylinos.cn>
Link: https://patch.msgid.link/20260720084426.1632508-1-lilinmao@kylinos.cn
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index 5e7c46dd7823..49ea2ed0996b 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -1048,7 +1048,7 @@ static void vc4_bo_cache_destroy(struct drm_device *dev, void *unused)
 	struct vc4_dev *vc4 = to_vc4_dev(dev);
 	int i;
 
-	timer_delete(&vc4->bo_cache.time_timer);
+	timer_shutdown_sync(&vc4->bo_cache.time_timer);
 	cancel_work_sync(&vc4->bo_cache.time_work);
 
 	vc4_bo_cache_purge(dev);