ipv4: add mc_count to in_device.

This patch add mc_count to struct in_device and updates
increment/decrement/initilaize of this field in IPv4 and in IPv6.

- Also printing the vfs /proc entry (/proc/net/igmp) is adjusted to
use the new mc_count.

Signed-off-by: Rami Rosen <ramirose@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index c6f51ad..06fcdb4 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -25,6 +25,7 @@
 	struct in_ifaddr	*ifa_list;	/* IP ifaddr chain		*/
 	rwlock_t		mc_list_lock;
 	struct ip_mc_list	*mc_list;	/* IP multicast filter chain    */
+	int			mc_count;	          /* Number of installed mcasts	*/
 	spinlock_t		mc_tomb_lock;
 	struct ip_mc_list	*mc_tomb;
 	unsigned long		mr_v1_seen;
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index f70fac6..7f9e337 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1234,6 +1234,7 @@
 	write_lock_bh(&in_dev->mc_list_lock);
 	im->next=in_dev->mc_list;
 	in_dev->mc_list=im;
+	in_dev->mc_count++;
 	write_unlock_bh(&in_dev->mc_list_lock);
 #ifdef CONFIG_IP_MULTICAST
 	igmpv3_del_delrec(in_dev, im->multiaddr);
@@ -1282,6 +1283,7 @@
 			if (--i->users == 0) {
 				write_lock_bh(&in_dev->mc_list_lock);
 				*ip = i->next;
+				in_dev->mc_count--;
 				write_unlock_bh(&in_dev->mc_list_lock);
 				igmp_group_dropped(i);
 
@@ -1330,6 +1332,7 @@
 	setup_timer(&in_dev->mr_gq_timer, igmp_gq_timer_expire,
 			(unsigned long)in_dev);
 	in_dev->mr_ifc_count = 0;
+	in_dev->mc_count     = 0;
 	setup_timer(&in_dev->mr_ifc_timer, igmp_ifc_timer_expire,
 			(unsigned long)in_dev);
 	in_dev->mr_qrv = IGMP_Unsolicited_Report_Count;
@@ -1369,8 +1372,8 @@
 	write_lock_bh(&in_dev->mc_list_lock);
 	while ((i = in_dev->mc_list) != NULL) {
 		in_dev->mc_list = i->next;
+		in_dev->mc_count--;
 		write_unlock_bh(&in_dev->mc_list_lock);
-
 		igmp_group_dropped(i);
 		ip_ma_put(i);
 
@@ -2383,7 +2386,7 @@
 
 		if (state->in_dev->mc_list == im) {
 			seq_printf(seq, "%d\t%-10s: %5d %7s\n",
-				   state->dev->ifindex, state->dev->name, state->dev->mc_count, querier);
+				   state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);
 		}
 
 		seq_printf(seq,