1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index a34d6bf5e43b..cc70ecfc7062 100644
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -429,11 +429,13 @@ static void slip_write_wakeup(struct tty_struct *tty)
         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
                 return;
 
+        spin_lock(&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);
                 sl_unlock(sl);
                 return;
         }
@@ -441,6 +443,7 @@ static void slip_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);
 }
 
 static void sl_tx_timeout(struct net_device *dev)