From 6776485deef32900c119a61d43faecb515d3b20b Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Mon, 20 Jun 2016 08:21:00 -0400
Subject: [PATCH] quagga: Allow compile time determination of v6 RR semantics

The patches to allow kernel v6 Route Replacement semantics
to work correctly are on a very recent kernel.  If you are
compiling on a linux kernel where it's broken, just
compile with --disable-rr-semantics.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
(cherry picked from commit 76981cd383e4bed69454bcc4151a0aae89e8ca84)
---
 configure.ac       | 6 ++++++
 zebra/rt_netlink.c | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/configure.ac b/configure.ac
index 8758d9d3c1..8338ad1462 100755
--- a/configure.ac
+++ b/configure.ac
@@ -304,6 +304,8 @@ AC_ARG_ENABLE(werror,
   AS_HELP_STRING([--enable-werror], [enable -Werror (recommended for developers only)]))
 AC_ARG_ENABLE(cumulus,
 [  --enable-cumulus     enable Cumulus Switch Special Extensions])
+AC_ARG_ENABLE(rr-semantics,
+  AS_HELP_STRING([--disable-rr-semantics], [disable the v6 Route Replace semantics]))
 
 if test x"${enable_gcc_ultra_verbose}" = x"yes" ; then
   CFLAGS="${CFLAGS} -W -Wcast-qual -Wstrict-prototypes"
@@ -345,6 +347,10 @@ case "${enable_systemd}" in
   "*") ;;
 esac
 
+if test "${enable_rr_semantics}" != "no" ; then
+  AC_DEFINE(HAVE_V6_RR_SEMANTICS,, Compile in v6 Route Replacement Semantics)
+fi
+
 if test "${enable_poll}" = "yes" ; then
   AC_DEFINE(HAVE_POLL,,Compile systemd support in)
 fi
diff --git a/zebra/rt_netlink.c b/zebra/rt_netlink.c
index e52fcd4342..1f7b1a9cff 100644
--- a/zebra/rt_netlink.c
+++ b/zebra/rt_netlink.c
@@ -2390,7 +2390,12 @@ kernel_add_ipv6 (struct prefix *p, struct rib *rib)
 int
 kernel_update_ipv6 (struct prefix *p, struct rib *rib)
 {
+#if defined (HAVE_V6_RR_SEMANTICS)
   return netlink_route_multipath (RTM_NEWROUTE, p, rib, AF_INET6, 1);
+#else
+  kernel_delete_ipv6 (p, rib);
+  return kernel_add_ipv6 (p, rib);
+#endif
 }
 
 int
-- 
2.39.5