From 8b451b7d7e95f133fdc3b9f84b9a60e7d1136ce2 Mon Sep 17 00:00:00 2001 From: Duoming Zhou Date: Mon, 25 Apr 2022 12:24:00 +0800 Subject: can: grcan: grcan_close(): fix deadlock commit 47f070a63e735bcc8d481de31be1b5a1aa62b31c upstream. There are deadlocks caused by del_timer_sync(&priv->hang_timer) and del_timer_sync(&priv->rr_timer) in grcan_close(), one of the deadlocks are shown below: (Thread 1) | (Thread 2) | grcan_reset_timer() grcan_close() | mod_timer() spin_lock_irqsave() //(1) | (wait a time) ... | grcan_initiate_running_reset() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold priv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need priv->lock in position (2) of thread 2. As a result, grcan_close() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irqsave(), which could let timer handler to obtain the needed lock. Link: https://lore.kernel.org/all/20220425042400.66517-1-duoming@zju.edu.cn Fixes: 6cec9b07fe6a ("can: grcan: Add device driver for GRCAN and GRHCAN cores") Cc: stable@vger.kernel.org Signed-off-by: Duoming Zhou Reviewed-by: Andreas Larsson Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/grcan.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c index b8f1f2b69dd3..08910f551a57 100644 --- a/drivers/net/can/grcan.c +++ b/drivers/net/can/grcan.c @@ -1113,8 +1113,10 @@ static int grcan_close(struct net_device *dev) priv->closing = true; if (priv->need_txbug_workaround) { + spin_unlock_irqrestore(&priv->lock, flags); del_timer_sync(&priv->hang_timer); del_timer_sync(&priv->rr_timer); + spin_lock_irqsave(&priv->lock, flags); } netif_stop_queue(dev); grcan_stop_hardware(dev); -- cgit v1.2.3