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authorDuoming Zhou <duoming@zju.edu.cn>2022-04-25 12:24:00 +0800
committerMarc Kleine-Budde <mkl@pengutronix.de>2022-04-29 12:09:19 +0200
commit47f070a63e735bcc8d481de31be1b5a1aa62b31c (patch)
treef385a5fbed2d7b79da328eedd6c8ddcea9522ee7
parent72ed3ee9fa0b461ad086403a8b5336154bd82234 (diff)
downloadlinux-47f070a63e735bcc8d481de31be1b5a1aa62b31c.tar.bz2
can: grcan: grcan_close(): fix deadlock
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 <duoming@zju.edu.cn> Reviewed-by: Andreas Larsson <andreas@gaisler.com> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
-rw-r--r--drivers/net/can/grcan.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c
index d0c5a7a60daf..1189057b5d68 100644
--- a/drivers/net/can/grcan.c
+++ b/drivers/net/can/grcan.c
@@ -1102,8 +1102,10 @@ 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);