Index: sys/netinet/in.c
===================================================================
RCS file: /cvsroot/src/sys/netinet/in.c,v
retrieving revision 1.147
diff -p -u -r1.147 in.c
--- sys/netinet/in.c	1 Jul 2014 05:49:18 -0000	1.147
+++ sys/netinet/in.c	22 Aug 2014 16:38:57 -0000
@@ -1123,6 +1123,7 @@ in_addmulti(struct in_addr *ap, ifnet_t 
 	/*
 	 * See if address already in list.
 	 */
+	mutex_enter(softnet_lock);
 	rw_enter(&in_multilock, RW_WRITER);
 	inm = in_lookup_multi(*ap, ifp);
 	if (inm != NULL) {
@@ -1131,6 +1132,7 @@ in_addmulti(struct in_addr *ap, ifnet_t 
 		 */
 		inm->inm_refcount++;
 		rw_exit(&in_multilock);
+		mutex_exit(softnet_lock);
 		return inm;
 	}
 
@@ -1140,6 +1142,7 @@ in_addmulti(struct in_addr *ap, ifnet_t 
 	inm = pool_get(&inmulti_pool, PR_NOWAIT);
 	if (inm == NULL) {
 		rw_exit(&in_multilock);
+		mutex_exit(softnet_lock);
 		return NULL;
 	}
 	inm->inm_addr = *ap;
@@ -1153,6 +1156,7 @@ in_addmulti(struct in_addr *ap, ifnet_t 
 	sockaddr_in_init(&sin, ap, 0);
 	if (if_mcast_op(ifp, SIOCADDMULTI, sintosa(&sin)) != 0) {
 		rw_exit(&in_multilock);
+		mutex_exit(softnet_lock);
 		pool_put(&inmulti_pool, inm);
 		return NULL;
 	}
@@ -1162,6 +1166,7 @@ in_addmulti(struct in_addr *ap, ifnet_t 
 	 */
 	if (igmp_joingroup(inm) != 0) {
 		rw_exit(&in_multilock);
+		mutex_exit(softnet_lock);
 		pool_put(&inmulti_pool, inm);
 		return NULL;
 	}
@@ -1170,6 +1175,7 @@ in_addmulti(struct in_addr *ap, ifnet_t 
 	    inm, inm_list);
 	in_multientries++;
 	rw_exit(&in_multilock);
+	mutex_exit(softnet_lock);
 
 	return inm;
 }
Index: sys/netinet/igmp.c
===================================================================
RCS file: /cvsroot/src/sys/netinet/igmp.c,v
retrieving revision 1.55
diff -p -u -r1.55 igmp.c
--- sys/netinet/igmp.c	29 May 2014 23:02:48 -0000	1.55
+++ sys/netinet/igmp.c	22 Aug 2014 16:38:57 -0000
@@ -469,6 +469,8 @@ igmp_input(struct mbuf *m, ...)
 int
 igmp_joingroup(struct in_multi *inm)
 {
+
+	KASSERT(mutex_owned(softnet_lock));
 	KASSERT(in_multi_lock_held());
 	inm->inm_state = IGMP_IDLE_MEMBER;
 
@@ -494,6 +496,8 @@ igmp_joingroup(struct in_multi *inm)
 void
 igmp_leavegroup(struct in_multi *inm)
 {
+
+	KASSERT(mutex_owned(softnet_lock));
 	KASSERT(in_multi_lock_held());
 
 	switch (inm->inm_state) {