[PATCH 063/100] ipv6 mcast: use in6_dev_put in timer handlers instead of __in6_dev_put

[Luis Henriques]

3.5.7.23 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Salam Noureddine <noureddine at aristanetworks.com>

commit 9260d3e1013701aa814d10c8fc6a9f92bd17d643 upstream.

It is possible for the timer handlers to run after the call to
ipv6_mc_down so use in6_dev_put instead of __in6_dev_put in the
handler function in order to do proper cleanup when the refcnt
reaches 0. Otherwise, the refcnt can reach zero without the
inet6_dev being destroyed and we end up leaking a reference to
the net_device and see messages like the following,

unregister_netdevice: waiting for eth0 to become free. Usage count = 1

Tested on linux-3.4.43.

Signed-off-by: Salam Noureddine <noureddine at aristanetworks.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ luis: backported to 3.5 (based on davem backport to 3.4):
  - dropped changes to mld_dad_timer_expire() ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/ipv6/mcast.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 2e97228..4441a0f 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -2149,7 +2149,7 @@ static void mld_gq_timer_expire(unsigned long data)
 
 	idev->mc_gq_running = 0;
 	mld_send_report(idev, NULL);
-	__in6_dev_put(idev);
+	in6_dev_put(idev);
 }
 
 static void mld_ifc_timer_expire(unsigned long data)
@@ -2162,7 +2162,7 @@ static void mld_ifc_timer_expire(unsigned long data)
 		if (idev->mc_ifc_count)
 			mld_ifc_start_timer(idev, idev->mc_maxdelay);
 	}
-	__in6_dev_put(idev);
+	in6_dev_put(idev);
 }
 
 static void mld_ifc_event(struct inet6_dev *idev)
-- 
1.8.3.2