[PATCH 5.15.y] mailbox: altera: shut down RX polling timer on channel teardown

[Sasha Levin <sashal@kernel.org>]

From: Runyu Xiao <runyu.xiao@seu.edu.cn>

[ Upstream commit 0cf10e65639cba32d05994f85e6a8f08dd0ffe08 ]

The RX polling callback unconditionally rearms the timer after it
processes mailbox data.  altera_mbox_shutdown() uses
timer_delete_sync(), which waits for a running callback but does not
prevent that callback from rearming the timer after the deletion.

Use timer_shutdown_sync() for the final polling teardown so the timer
cannot be queued again while the mailbox channel is being released.
The timer is reinitialized with timer_setup() on a later channel startup,
so polling mode remains reusable.

Fixes: f62092f6d77d ("mailbox: Add Altera mailbox driver")
Cc: stable@vger.kernel.org
Assisted-by: Codex:GPT-5
Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>
[ sashal: replaced del_timer_sync() instead of timer_delete_sync() ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/mailbox/mailbox-altera.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mailbox/mailbox-altera.c b/drivers/mailbox/mailbox-altera.c
index 75282666fb06c..2b1be8828440e 100644
--- a/drivers/mailbox/mailbox-altera.c
+++ b/drivers/mailbox/mailbox-altera.c
@@ -270,7 +270,7 @@ static void altera_mbox_shutdown(struct mbox_chan *chan)
 		writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
 		free_irq(mbox->irq, chan);
 	} else if (!mbox->is_sender) {
-		del_timer_sync(&mbox->rxpoll_timer);
+		timer_shutdown_sync(&mbox->rxpoll_timer);
 	}
 }
 
-- 
2.53.0