2 files changed, 40 insertions, 5 deletions

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index d97268e8ff10..ab64d9f2eef9 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1559,21 +1559,45 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
 }
 
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
+static bool fib_good_nh(const struct fib_nh *nh)
+{
+        int state = NUD_REACHABLE;
+
+        if (nh->nh_scope == RT_SCOPE_LINK) {
+                struct neighbour *n;
+
+                rcu_read_lock_bh();
+
+                n = __ipv4_neigh_lookup_noref(nh->nh_dev, nh->nh_gw);
+                if (n)
+                        state = n->nud_state;
+
+                rcu_read_unlock_bh();
+        }
+
+        return !!(state & NUD_VALID);
+}
 
 void fib_select_multipath(struct fib_result *res, int hash)
 {
         struct fib_info *fi = res->fi;
+        struct net *net = fi->fib_net;
+        bool first = false;
 
         for_nexthops(fi) {
                 if (hash > atomic_read(&nh->nh_upper_bound))
                         continue;
 
-                res->nh_sel = nhsel;
-                return;
+                if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
+                    fib_good_nh(nh)) {
+                        res->nh_sel = nhsel;
+                        return;
+                }
+                if (!first) {
+                        res->nh_sel = nhsel;
+                        first = true;
+                }
         } endfor_nexthops(fi);
-
-        /* Race condition: route has just become dead. */
-        res->nh_sel = 0;
 }
 #endif
 
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1e1fe6086dd9..bb0419582b8d 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -960,6 +960,17 @@ static struct ctl_table ipv4_net_table[] = {
                 .mode           = 0644,
                 .proc_handler   = proc_dointvec,
         },
+#ifdef CONFIG_IP_ROUTE_MULTIPATH
+        {
+                .procname       = "fib_multipath_use_neigh",
+                .data           = &init_net.ipv4.sysctl_fib_multipath_use_neigh,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &zero,
+                .extra2         = &one,
+        },
+#endif
         { }
 };