can: slcan: Fix spinlock variant
authorAlexander Stein <alexander.stein@systec-electronic.com>
Tue, 15 Apr 2014 14:51:04 +0000 (16:51 +0200)
committerMarc Kleine-Budde <mkl@pengutronix.de>
Thu, 24 Apr 2014 20:32:41 +0000 (22:32 +0200)
slc_xmit is called within softirq context and locks sl->lock, but
slcan_write_wakeup is not softirq context, so we need to use
spin_[un]lock_bh!
Detected using kernel lock debugging mechanism.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
drivers/net/can/slcan.c

index f5b16e0e3a125f4e38a93408e92b8218808339af..dcf9196f63164b0db099e17a8d1208d9ac158ac4 100644 (file)
@@ -322,13 +322,13 @@ static void slcan_write_wakeup(struct tty_struct *tty)
        if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
                return;
 
-       spin_lock(&sl->lock);
+       spin_lock_bh(&sl->lock);
        if (sl->xleft <= 0)  {
                /* Now serial buffer is almost free & we can start
                 * transmission of another packet */
                sl->dev->stats.tx_packets++;
                clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-               spin_unlock(&sl->lock);
+               spin_unlock_bh(&sl->lock);
                netif_wake_queue(sl->dev);
                return;
        }
@@ -336,7 +336,7 @@ static void slcan_write_wakeup(struct tty_struct *tty)
        actual = tty->ops->write(tty, sl->xhead, sl->xleft);
        sl->xleft -= actual;
        sl->xhead += actual;
-       spin_unlock(&sl->lock);
+       spin_unlock_bh(&sl->lock);
 }
 
 /* Send a can_frame to a TTY queue. */