Hi

When ifmcaddr6's mca_sources is not NULL, but none of the sources in the list can be included in report,
(For example: when filter mode is exclude and the only source in the list has include count greater than zero.)
add_grec(...) may returns without add any data to the sk_buff. So MLD2_CHANGE_TO_EXCLUDE or MLD2_MODE_IS_EXCLUDE
report may be eliminated.

You can check this bug by test1.c in attachments. You will notice that there is no MLD2_CHANGE_TO_EXCLUDE report.

Regards

Signed-off-by: Yan Zheng<yanzheng@21cn.com>

Index:net/ipv6/mcast.c
==============================================================
--- linux-2.6.14/net/ipv6/mcast.c	2005-11-09 16:00:48.000000000 +0800
+++ linux/net/ipv6/mcast.c	2005-11-09 19:47:50.000000000 +0800
@@ -1445,18 +1445,21 @@ static struct sk_buff *add_grec(struct s
 	struct mld2_report *pmr;
 	struct mld2_grec *pgr = NULL;
 	struct ip6_sf_list *psf, *psf_next, *psf_prev, **psf_list;
-	int scount, first, isquery, truncate;
+	int scount, first, isquery, ischange, truncate;
 
 	if (pmc->mca_flags & MAF_NOREPORT)
 		return skb;
 
 	isquery = type == MLD2_MODE_IS_INCLUDE ||
 		  type == MLD2_MODE_IS_EXCLUDE;
+	ischange = type == MLD2_CHANGE_TO_INCLUDE ||
+		   type == MLD2_CHANGE_TO_EXCLUDE; 
 	truncate = type == MLD2_MODE_IS_EXCLUDE ||
-		    type == MLD2_CHANGE_TO_EXCLUDE;
+		   type == MLD2_CHANGE_TO_EXCLUDE;
 
 	psf_list = sdeleted ? &pmc->mca_tomb : &pmc->mca_sources;
 
+#if 0
 	if (!*psf_list) {
 		if (type == MLD2_ALLOW_NEW_SOURCES ||
 		    type == MLD2_BLOCK_OLD_SOURCES)
@@ -1474,12 +1477,15 @@ static struct sk_buff *add_grec(struct s
 		}
 		return skb;
 	}
+#endif
 	pmr = skb ? (struct mld2_report *)skb->h.raw : NULL;
 
 	/* EX and TO_EX get a fresh packet, if needed */
-	if (truncate) {
-		if (pmr && pmr->ngrec &&
-		    AVAILABLE(skb) < grec_size(pmc, type, gdeleted, sdeleted)) {
+	if (truncate || ischange) {
+		int min_len;
+		min_len	= truncate ? grec_size(pmc, type, gdeleted, sdeleted) : 
+			  (sizeof(struct mld2_grec) + sizeof(struct in6_addr));
+		if (pmr && pmr->ngrec && AVAILABLE(skb) < min_len) {
 			if (skb)
 				mld_sendpack(skb);
 			skb = mld_newpack(dev, dev->mtu);
@@ -1488,6 +1494,10 @@ static struct sk_buff *add_grec(struct s
 	first = 1;
 	scount = 0;
 	psf_prev = NULL;
+	if (ischange || type == MLD2_MODE_IS_EXCLUDE) {
+		skb = add_grhead(skb, pmc, type, &pgr);
+		first = 0;
+	}
 	for (psf=*psf_list; psf; psf=psf_next) {
 		struct in6_addr *psrc;