bonding: fix to rejoin multicast groups immediately

The IGMP specs states that if the system receives a
membership report, it shouldn't send another for the
next minute. However, if a link failure happens right
after that, the backup slave and the switch connected
to this slave will not know about the multicast and
the traffic will hang for about a minute.

This patch fixes it to rejoin multicast groups immediately
after a failover restoring the multicast traffic.

Signed-off-by: Flavio Leitner <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/igmp.c

···
 	if (im->multiaddr == IGMP_ALL_HOSTS)
 		return;
 
-	if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev)) {
-		igmp_mod_timer(im, IGMP_Initial_Report_Delay);
-		return;
-	}
-	/* else, v3 */
-	im->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
-		IGMP_Unsolicited_Report_Count;
-	igmp_ifc_event(in_dev);
+	/* a failover is happening and switches
+	 * must be notified immediately */
+	if (IGMP_V1_SEEN(in_dev))
+		igmp_send_report(in_dev, im, IGMP_HOST_MEMBERSHIP_REPORT);
+	else if (IGMP_V2_SEEN(in_dev))
+		igmp_send_report(in_dev, im, IGMPV2_HOST_MEMBERSHIP_REPORT);
+	else
+		igmp_send_report(in_dev, im, IGMPV3_HOST_MEMBERSHIP_REPORT);
 #endif
 }
 EXPORT_SYMBOL(ip_mc_rejoin_group);