[PATCH 3.16 181/328] igmp: fix incorrect unsolicit report count after link down and up

[Ben Hutchings]

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Hangbin Liu <liuhangbin@xxxxxxxxx>

commit ff06525fcb8ae3c302ac1319bf6c07c026dea964 upstream.

After link down and up, i.e. when call ip_mc_up(), we doesn't init
im->unsolicit_count. So after igmp_timer_expire(), we will not start
timer again and only send one unsolicit report at last.

Fix it by initializing im->unsolicit_count in igmp_group_added(), so
we can respect igmp robustness value.

Fixes: 24803f38a5c0b ("igmp: do not remove igmp souce list info when set link down")
Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16:
 - Keep using constant IGMP_Unsolicited_Report_Count
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1256,6 +1256,8 @@ static void igmp_group_added(struct ip_m
 
 	if (in_dev->dead)
 		return;
+
+	im->unsolicit_count = IGMP_Unsolicited_Report_Count;
 	if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev)) {
 		spin_lock_bh(&im->lock);
 		igmp_start_timer(im, IGMP_Initial_Report_Delay);
@@ -1360,7 +1362,6 @@ void ip_mc_inc_group(struct in_device *i
 	spin_lock_init(&im->lock);
 #ifdef CONFIG_IP_MULTICAST
 	setup_timer(&im->timer, &igmp_timer_expire, (unsigned long)im);
-	im->unsolicit_count = IGMP_Unsolicited_Report_Count;
 #endif
 
 	im->next_rcu = in_dev->mc_list;