netdev - [PATCH net-next 12/29] can: slcan: do not sleep with a spin lock held

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Date:   Wed, 20 Jul 2022 10:10:17 +0200
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
        kernel@...gutronix.de,
        Dario Binacchi <dario.binacchi@...rulasolutions.com>,
        kernel test robot <oliver.sang@...el.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net-next 12/29] can: slcan: do not sleep with a spin lock held

From: Dario Binacchi <dario.binacchi@...rulasolutions.com>

We can't call close_candev() with a spin lock held, so release the lock
before calling it. After calling close_candev(), we can update the
fields of the private `struct can_priv' without having to acquire the
lock.

Fixes: c4e54b063f42f ("can: slcan: use CAN network device driver API")
Link: https://lore.kernel.org/linux-kernel/Ysrf1Yc5DaRGN1WE@xsang-OptiPlex-9020/
Link: https://lore.kernel.org/all/20220715072951.859586-1-dario.binacchi@amarulasolutions.com
Reported-by: kernel test robot <oliver.sang@...el.com>
Signed-off-by: Dario Binacchi <dario.binacchi@...rulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/slcan/slcan-core.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index d9bf75a25988..057b211f3e7f 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -688,15 +688,14 @@ static int slc_close(struct net_device *dev)
 		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 	}
 	netif_stop_queue(dev);
+	sl->rcount   = 0;
+	sl->xleft    = 0;
+	spin_unlock_bh(&sl->lock);
 	close_candev(dev);
 	sl->can.state = CAN_STATE_STOPPED;
 	if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN)
 		sl->can.bittiming.bitrate = CAN_BITRATE_UNSET;
 
-	sl->rcount   = 0;
-	sl->xleft    = 0;
-	spin_unlock_bh(&sl->lock);
-
 	return 0;
 }
 
-- 
2.35.1