[3.13.y.z extended stable] Patch "slip: fix spinlock variant" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    slip: fix spinlock variant

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 57e9b3dcbc31003eee10dace44088eea3fb88454 Mon Sep 17 00:00:00 2001
From: Oliver Hartkopp <socketcan at hartkopp.net>
Date: Sat, 26 Apr 2014 21:18:32 +0200
Subject: slip: fix spinlock variant

[ Upstream commit ddcde142bed44490e338ed1124cb149976d355bb ]

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 at hartkopp.net>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/slip/slip.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

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)
--
1.9.1