ipv6: ignore dst hint for multipath routes

Route hints when the nexthop is part of a multipath group causes packets
in the same receive batch to be sent to the same nexthop irrespective of
the multipath hash of the packet. So, do not extract route hint for
packets whose destination is part of a multipath group.

A new SKB flag IP6SKB_MULTIPATH is introduced for this purpose, set the
flag when route is looked up in fib6_select_path() and use it in
ip6_can_use_hint() to check for the existence of the flag.

Fixes: 197dbf24e360 ("ipv6: introduce and uses route look hints for list input.")
Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 5883551b1ee874b8c217bbefa5cb5feeb8e894c1..af8a771a053c51eed297516f927a5fd003315ef4 100644 (file)
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -147,6 +147,7 @@ struct inet6_skb_parm {
 #define IP6SKB_JUMBOGRAM      128
 #define IP6SKB_SEG6          256
 #define IP6SKB_FAKEJUMBO      512
+#define IP6SKB_MULTIPATH      1024
 };
 
 #if defined(CONFIG_NET_L3_MASTER_DEV)

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index d94041bb42872f02eaaa5bd2f64ae2301a8a48a4..b8378814532cead0275e8b7a656f78450993f619 100644 (file)
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -99,7 +99,8 @@ static bool ip6_can_use_hint(const struct sk_buff *skb,
 static struct sk_buff *ip6_extract_route_hint(const struct net *net,
                                              struct sk_buff *skb)
 {
-       if (fib6_routes_require_src(net) || fib6_has_custom_rules(net))
+       if (fib6_routes_require_src(net) || fib6_has_custom_rules(net) ||
+           IP6CB(skb)->flags & IP6SKB_MULTIPATH)
                return NULL;
 
        return skb;

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 846aec8e00933e9d87444b292d797dbf1a5375fa..01d6d352850ad4a2ecabc5ac3e6390b98a221866 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -423,6 +423,9 @@ void fib6_select_path(const struct net *net, struct fib6_result *res,
        if (match->nh && have_oif_match && res->nh)
                return;
 
+       if (skb)
+               IP6CB(skb)->flags |= IP6SKB_MULTIPATH;
+
        /* We might have already computed the hash for ICMPv6 errors. In such
         * case it will always be non-zero. Otherwise now is the time to do it.
         */