From: Duoming Zhou <duoming@xxxxxxxxxx>
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@xxxxxxxxxx
Fixes: 6cec9b07fe6a ("can: grcan: Add device driver for GRCAN and GRHCAN cores")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
Reviewed-by: Andreas Larsson <andreas@xxxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/can/grcan.c | 2 ++
1 file changed, 2 insertions(+)
--- a/drivers/net/can/grcan.c
+++ b/drivers/net/can/grcan.c
@@ -1117,8 +1117,10 @@ static int grcan_close(struct net_device
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);
