[PATCH net-next] ipv6: Restore RTF_ADDRCONF check in rt6_qualify_for_ecmp

[PATCH net-next] ipv6: Restore RTF_ADDRCONF check in rt6_qualify_for_ecmp

[David Ahern]

From: David Ahern <dsahern@gmail.com>

The RTF_ADDRCONF flag filters out routes added by RA's in determining
which routes can be appended to an existing one to create a multipath
route. Restore the flag check and add a comment to document the RA piece.

Fixes: 4e54507ab1a9 ("ipv6: Simplify rt6_qualify_for_ecmp")
Signed-off-by: David Ahern <dsahern@gmail.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
 include/net/ip6_route.h                               | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 34d9053e5cf0..8f31c2ddc538 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -4928,7 +4928,7 @@ static void mlxsw_sp_rt6_destroy(struct mlxsw_sp_rt6 *mlxsw_sp_rt6)
 static bool mlxsw_sp_fib6_rt_can_mp(const struct fib6_info *rt)
 {
 	/* RTF_CACHE routes are ignored */
-	return rt->fib6_nh.fib_nh_gw_family;
+	return !(rt->fib6_flags & RTF_ADDRCONF) && rt->fib6_nh.fib_nh_gw_family;
 }
 
 static struct fib6_info *
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 518d97fbe074..df9cebc2b20c 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -68,7 +68,9 @@ static inline bool rt6_need_strict(const struct in6_addr *daddr)
 
 static inline bool rt6_qualify_for_ecmp(const struct fib6_info *f6i)
 {
-	return f6i->fib6_nh.fib_nh_gw_family;
+	/* the RTF_ADDRCONF flag filters out RA's */
+	return !(f6i->fib6_flags & RTF_ADDRCONF) &&
+		f6i->fib6_nh.fib_nh_gw_family;
 }
 
 void ip6_route_input(struct sk_buff *skb);
-- 
2.11.0

Re: [PATCH net-next] ipv6: Restore RTF_ADDRCONF check in rt6_qualify_for_ecmp

[David Miller]

From: David Ahern <dsahern@kernel.org>
Date: Sun, 21 Apr 2019 17:39:18 -0700

> From: David Ahern <dsahern@gmail.com>
> 
> The RTF_ADDRCONF flag filters out routes added by RA's in determining
> which routes can be appended to an existing one to create a multipath
> route. Restore the flag check and add a comment to document the RA piece.
> 
> Fixes: 4e54507ab1a9 ("ipv6: Simplify rt6_qualify_for_ecmp")
> Signed-off-by: David Ahern <dsahern@gmail.com>

Applied.