bonding: IGMP handling cleanup

Instead of iterating in_dev->mc_list from bonding driver, its better
to call a helper function provided by igmp.c
Details of implementation (locking) are private to igmp code.

ip_mc_rejoin_group(struct ip_mc_list *im) becomes
ip_mc_rejoin_groups(struct in_device *in_dev);
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -873,15 +873,11 @@ static void bond_mc_del(struct bonding *bond, void *addr)
 static void __bond_resend_igmp_join_requests(struct net_device *dev)
 {
 	struct in_device *in_dev;
-	struct ip_mc_list *im;
 
 	rcu_read_lock();
 	in_dev = __in_dev_get_rcu(dev);
-	if (in_dev) {
-		for (im = in_dev->mc_list; im; im = im->next)
-			ip_mc_rejoin_group(im);
-	}
-
+	if (in_dev)
+			ip_mc_rejoin_groups(in_dev);
 	rcu_read_unlock();
 }
 

include/linux/igmp.h

@@ -238,7 +238,7 @@ extern void ip_mc_unmap(struct in_device *);
 extern void ip_mc_remap(struct in_device *);
 extern void ip_mc_dec_group(struct in_device *in_dev, __be32 addr);
 extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);
-extern void ip_mc_rejoin_group(struct ip_mc_list *im);
+extern void ip_mc_rejoin_groups(struct in_device *in_dev);
 
 #endif
 #endif

net/ipv4/igmp.c

@@ -1267,26 +1267,32 @@ EXPORT_SYMBOL(ip_mc_inc_group);
 
 /*
  *	Resend IGMP JOIN report; used for bonding.
+ *	Called with rcu_read_lock()
  */
-void ip_mc_rejoin_group(struct ip_mc_list *im)
+void ip_mc_rejoin_groups(struct in_device *in_dev)
 {
 #ifdef CONFIG_IP_MULTICAST
-	struct in_device *in_dev = im->interface;
+	struct ip_mc_list *im;
+	int type;
 
-	if (im->multiaddr == IGMP_ALL_HOSTS)
-		return;
+	for_each_pmc_rcu(in_dev, im) {
+		if (im->multiaddr == IGMP_ALL_HOSTS)
+			continue;
 
-	/* 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);
+		/* a failover is happening and switches
+		 * must be notified immediately
+		 */
+		if (IGMP_V1_SEEN(in_dev))
+			type = IGMP_HOST_MEMBERSHIP_REPORT;
+		else if (IGMP_V2_SEEN(in_dev))
+			type = IGMPV2_HOST_MEMBERSHIP_REPORT;
+		else
+			type = IGMPV3_HOST_MEMBERSHIP_REPORT;
+		igmp_send_report(in_dev, im, type);
+	}
 #endif
 }
-EXPORT_SYMBOL(ip_mc_rejoin_group);
+EXPORT_SYMBOL(ip_mc_rejoin_groups);
 
 /*
  *	A socket has left a multicast group on device dev