From 32019e651c6fcee6bad6b6adb171feea5af0d16b Mon Sep 17 00:00:00 2001
From: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Date: Sun, 24 Jul 2011 11:44:34 +0000
Subject: [PATCH] ipv6: Do not leave router anycast address for /127 prefixes.
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Original commit 2bda8a0c8af... "Disable router anycast
address for /127 prefixes" says:

|   No need for matching code in addrconf_leave_anycast() as it
|   will silently ignore any attempt to leave an unknown anycast
|   address.

After analysis, because 1) we may add two or more prefixes on the
same interface, or 2)user may have manually joined that anycast,
we may hit chances to have anycast address which as if we had
generated one by /127 prefix and we should not leave from subnet-
router anycast address unconditionally.

CC: Bjørn Mork <bjorn@mork.no>
CC: Brian Haley <brian.haley@hp.com>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv6/addrconf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index a06c53c14d841..a55500cc0b29a 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1481,6 +1481,8 @@ static void addrconf_join_anycast(struct inet6_ifaddr *ifp)
 static void addrconf_leave_anycast(struct inet6_ifaddr *ifp)
 {
 	struct in6_addr addr;
+	if (ifp->prefix_len == 127) /* RFC 6164 */
+		return;
 	ipv6_addr_prefix(&addr, &ifp->addr, ifp->prefix_len);
 	if (ipv6_addr_any(&addr))
 		return;
-- 
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