can: slcan: do not sleep with a spin lock held

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@intel.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index d9bf75a25988e400472cf82481e2387f5e069937..057b211f3e7f4275747b0a78c8156368bb7ed3fa 100644 (file)
--- 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;
 }