1 files changed, 81 insertions, 39 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 3bc74ce78800..5e74a37695f7 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -723,48 +723,51 @@ fail:
         return err;
 }
 
-int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
+static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
+                                          struct dst_entry *dst,
+                                          struct flowi *fl)
 {
-        int err = 0;
+        struct ipv6_pinfo *np = inet6_sk(sk);
+        struct rt6_info *rt = (struct rt6_info *)dst;
 
-        *dst = NULL;
-        if (sk) {
-                struct ipv6_pinfo *np = inet6_sk(sk);
-        
-                *dst = sk_dst_check(sk, np->dst_cookie);
-                if (*dst) {
-                        struct rt6_info *rt = (struct rt6_info*)*dst;
-        
-                        /* Yes, checking route validity in not connected
-                         * case is not very simple. Take into account,
-                         * that we do not support routing by source, TOS,
-                         * and MSG_DONTROUTE            --ANK (980726)
-                         *
-                         * 1. If route was host route, check that
-                         *    cached destination is current.
-                         *    If it is network route, we still may
-                         *    check its validity using saved pointer
-                         *    to the last used address: daddr_cache.
-                         *    We do not want to save whole address now,
-                         *    (because main consumer of this service
-                         *    is tcp, which has not this problem),
-                         *    so that the last trick works only on connected
-                         *    sockets.
-                         * 2. oif also should be the same.
-                         */
-                        if (((rt->rt6i_dst.plen != 128 ||
-                              !ipv6_addr_equal(&fl->fl6_dst,
-                                               &rt->rt6i_dst.addr))
-                             && (np->daddr_cache == NULL ||
-                                 !ipv6_addr_equal(&fl->fl6_dst,
-                                                  np->daddr_cache)))
-                            || (fl->oif && fl->oif != (*dst)->dev->ifindex)) {
-                                dst_release(*dst);
-                                *dst = NULL;
-                        }
-                }
+        if (!dst)
+                goto out;
+
+        /* Yes, checking route validity in not connected
+         * case is not very simple. Take into account,
+         * that we do not support routing by source, TOS,
+         * and MSG_DONTROUTE            --ANK (980726)
+         *
+         * 1. If route was host route, check that
+         *    cached destination is current.
+         *    If it is network route, we still may
+         *    check its validity using saved pointer
+         *    to the last used address: daddr_cache.
+         *    We do not want to save whole address now,
+         *    (because main consumer of this service
+         *    is tcp, which has not this problem),
+         *    so that the last trick works only on connected
+         *    sockets.
+         * 2. oif also should be the same.
+         */
+        if (((rt->rt6i_dst.plen != 128 ||
+              !ipv6_addr_equal(&fl->fl6_dst, &rt->rt6i_dst.addr))
+             && (np->daddr_cache == NULL ||
+                 !ipv6_addr_equal(&fl->fl6_dst, np->daddr_cache)))
+            || (fl->oif && fl->oif != dst->dev->ifindex)) {
+                dst_release(dst);
+                dst = NULL;
         }
 
+out:
+        return dst;
+}
+
+static int ip6_dst_lookup_tail(struct sock *sk,
+                               struct dst_entry **dst, struct flowi *fl)
+{
+        int err;
+
         if (*dst == NULL)
                 *dst = ip6_route_output(sk, fl);
 
@@ -773,7 +776,6 @@ int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
 
         if (ipv6_addr_any(&fl->fl6_src)) {
                 err = ipv6_get_saddr(*dst, &fl->fl6_dst, &fl->fl6_src);
-
                 if (err)
                         goto out_err_release;
         }
@@ -786,8 +788,48 @@ out_err_release:
         return err;
 }
 
+/**
+ *      ip6_dst_lookup - perform route lookup on flow
+ *      @sk: socket which provides route info
+ *      @dst: pointer to dst_entry * for result
+ *      @fl: flow to lookup
+ *
+ *      This function performs a route lookup on the given flow.
+ *
+ *      It returns zero on success, or a standard errno code on error.
+ */
+int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
+{
+        *dst = NULL;
+        return ip6_dst_lookup_tail(sk, dst, fl);
+}
 EXPORT_SYMBOL_GPL(ip6_dst_lookup);
 
+/**
+ *      ip6_sk_dst_lookup - perform socket cached route lookup on flow
+ *      @sk: socket which provides the dst cache and route info
+ *      @dst: pointer to dst_entry * for result
+ *      @fl: flow to lookup
+ *
+ *      This function performs a route lookup on the given flow with the
+ *      possibility of using the cached route in the socket if it is valid.
+ *      It will take the socket dst lock when operating on the dst cache.
+ *      As a result, this function can only be used in process context.
+ *
+ *      It returns zero on success, or a standard errno code on error.
+ */
+int ip6_sk_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
+{
+        *dst = NULL;
+        if (sk) {
+                *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
+                *dst = ip6_sk_dst_check(sk, *dst, fl);
+        }
+
+        return ip6_dst_lookup_tail(sk, dst, fl);
+}
+EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup);
+
 static inline int ip6_ufo_append_data(struct sock *sk,
                         int getfrag(void *from, char *to, int offset, int len,
                         int odd, struct sk_buff *skb),