netdev - [PATCH] slip: fix spinlock variant

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Date:	Sat, 26 Apr 2014 21:18:32 +0200
From:	Oliver Hartkopp <socketcan@...tkopp.net>
To:	David Miller <davem@...emloft.net>
CC:	Andre Naujoks <nautsch2@...il.com>,
	Linux Netdev List <netdev@...r.kernel.org>,
	linux-can@...r.kernel.org,
	Alexander Stein <alexander.stein@...tec-electronic.com>
Subject: [PATCH] slip: fix spinlock variant

With commit cc9fa74e2a ("slip/slcan: added locking in wakeup function") a
formerly missing locking was added to slip.c and slcan.c by Andre Naujoks.

Alexander Stein contributed the fix 367525c8c2 ("can: slcan: Fix spinlock
variant") as the kernel lock debugging advised to use spin_lock_bh() instead
of just using spin_lock().

This fix has to be applied to the same code section in slip.c for the same
reason too.

Signed-off-by: Oliver Hartkopp <socketcan@...tkopp.net>

---

diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index cc70ecf..ad4a94e 100644
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -429,13 +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);
+	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);
 		sl_unlock(sl);
 		return;
 	}
@@ -443,7 +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);
+	spin_unlock_bh(&sl->lock);
 }
 
 static void sl_tx_timeout(struct net_device *dev)



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