1 files changed, 56 insertions, 0 deletions

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 1bf6fb906cfc..b15857d2b77e 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1136,6 +1136,62 @@ int fib_sync_down_dev(struct net_device *dev, int force)
         return ret;
 }
 
+/* Must be invoked inside of an RCU protected region.  */
+void fib_select_default(struct fib_result *res)
+{
+        struct fib_info *fi = NULL, *last_resort = NULL;
+        struct list_head *fa_head = res->fa_head;
+        struct fib_table *tb = res->table;
+        int order = -1, last_idx = -1;
+        struct fib_alias *fa;
+
+        list_for_each_entry_rcu(fa, fa_head, fa_list) {
+                struct fib_info *next_fi = fa->fa_info;
+
+                if (fa->fa_scope != res->scope ||
+                    fa->fa_type != RTN_UNICAST)
+                        continue;
+
+                if (next_fi->fib_priority > res->fi->fib_priority)
+                        break;
+                if (!next_fi->fib_nh[0].nh_gw ||
+                    next_fi->fib_nh[0].nh_scope != RT_SCOPE_LINK)
+                        continue;
+
+                fib_alias_accessed(fa);
+
+                if (fi == NULL) {
+                        if (next_fi != res->fi)
+                                break;
+                } else if (!fib_detect_death(fi, order, &last_resort,
+                                             &last_idx, tb->tb_default)) {
+                        fib_result_assign(res, fi);
+                        tb->tb_default = order;
+                        goto out;
+                }
+                fi = next_fi;
+                order++;
+        }
+
+        if (order <= 0 || fi == NULL) {
+                tb->tb_default = -1;
+                goto out;
+        }
+
+        if (!fib_detect_death(fi, order, &last_resort, &last_idx,
+                                tb->tb_default)) {
+                fib_result_assign(res, fi);
+                tb->tb_default = order;
+                goto out;
+        }
+
+        if (last_idx >= 0)
+                fib_result_assign(res, last_resort);
+        tb->tb_default = last_idx;
+out:
+        rcu_read_unlock();
+}
+
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 
 /*