[PATCH net v4 2/3] ipv6: allow to cache dst for a connected sk in ip6_sk_dst_lookup_flow()

[Alexey Kodanev]

Add 'connected' argument to ip6_sk_dst_lookup_flow() and update
the cache only if ip6_sk_dst_check() returns NULL and a socket
is connected.

The function is used as before, the new behavior for UDP sockets
in udpv6_sendmsg() will be enabled in the next patch.

Signed-off-by: Alexey Kodanev <alexey.koda...@oracle.com>
---
 include/net/ipv6.h    |  3 ++-
 net/ipv6/ip6_output.c | 15 ++++++++++++---
 net/ipv6/ping.c       |  2 +-
 net/ipv6/udp.c        |  2 +-
 4 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 1dd31ca..769550a 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -978,7 +978,8 @@ int ip6_dst_lookup(struct net *net, struct sock *sk, struct 
dst_entry **dst,
 struct dst_entry *ip6_dst_lookup_flow(const struct sock *sk, struct flowi6 
*fl6,
                                      const struct in6_addr *final_dst);
 struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
-                                        const struct in6_addr *final_dst);
+                                        const struct in6_addr *final_dst,
+                                        int connected);
 struct dst_entry *ip6_blackhole_route(struct net *net,
                                      struct dst_entry *orig_dst);
 
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ed87ce5..cdcdf37 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1122,23 +1122,32 @@ struct dst_entry *ip6_dst_lookup_flow(const struct sock 
*sk, struct flowi6 *fl6,
  *     @sk: socket which provides the dst cache and route info
  *     @fl6: flow to lookup
  *     @final_dst: final destination address for ipsec lookup
+ *     @connected: whether @sk is connected or not
  *
  *     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.
  *
+ *     In addition, for a connected socket, cache the dst in the socket
+ *     if the current cache is not valid.
+ *
  *     It returns a valid dst pointer on success, or a pointer encoded
  *     error code.
  */
 struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
-                                        const struct in6_addr *final_dst)
+                                        const struct in6_addr *final_dst,
+                                        int connected)
 {
        struct dst_entry *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
 
        dst = ip6_sk_dst_check(sk, dst, fl6);
-       if (!dst)
-               dst = ip6_dst_lookup_flow(sk, fl6, final_dst);
+       if (dst)
+               return dst;
+
+       dst = ip6_dst_lookup_flow(sk, fl6, final_dst);
+       if (connected && !IS_ERR(dst))
+               ip6_dst_store_flow(sk, dst_clone(dst), fl6);
 
        return dst;
 }
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index d12c55d..546f4a6 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -121,7 +121,7 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr 
*msg, size_t len)
        ipc6.tclass = np->tclass;
        fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 
-       dst = ip6_sk_dst_lookup_flow(sk, &fl6,  daddr);
+       dst = ip6_sk_dst_lookup_flow(sk, &fl6, daddr, 0);
        if (IS_ERR(dst))
                return PTR_ERR(dst);
        rt = (struct rt6_info *) dst;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 52e3ea0..e49dac4 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1289,7 +1289,7 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, 
size_t len)
 
        fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);
 
-       dst = ip6_sk_dst_lookup_flow(sk, &fl6, final_p);
+       dst = ip6_sk_dst_lookup_flow(sk, &fl6, final_p, 0);
        if (IS_ERR(dst)) {
                err = PTR_ERR(dst);
                dst = NULL;
-- 
1.8.3.1