ipv4 igmp: use in_dev_put in timer handlers instead of __in_dev_put

[ Upstream commit e2401654 ]

It is possible for the timer handlers to run after the call to
ip_mc_down so use in_dev_put instead of __in_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 in_device 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@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/ipv4/igmp.c

@@ -705,7 +705,7 @@ static void igmp_gq_timer_expire(unsigned long data)
 
 	in_dev->mr_gq_running = 0;
 	igmpv3_send_report(in_dev, NULL);
-	__in_dev_put(in_dev);
+	in_dev_put(in_dev);
 }
 
 static void igmp_ifc_timer_expire(unsigned long data)
@@ -717,7 +717,7 @@ static void igmp_ifc_timer_expire(unsigned long data)
 		in_dev->mr_ifc_count--;
 		igmp_ifc_start_timer(in_dev, IGMP_Unsolicited_Report_Interval);
 	}
-	__in_dev_put(in_dev);
+	in_dev_put(in_dev);
 }
 
 static void igmp_ifc_event(struct in_device *in_dev)