Re: [PATCH net v5 2/3] ipv6: allow to cache dst for a connected sk in ip6_sk_dst_lookup_flow()

[David Miller]

From: Alexey Kodanev 
Date: Mon,  2 Apr 2018 17:00:34 +0300

> +++ b/net/ipv6/ip6_output.c
> @@ -1105,23 +1105,32 @@ 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
 ...
>  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)

Please use type 'bool' and true/false for this new parameter.

Thank you.

[PATCH net v5 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 
---
 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 8606c91..07e94dc 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -977,7 +977,8 @@ 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 a8a9195..15724e0 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1105,23 +1105,32 @@ 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_sk_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, ,  daddr);
+   dst = ip6_sk_dst_lookup_flow(sk, , 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, , final_p);
+   dst = ip6_sk_dst_lookup_flow(sk, , final_p, 0);
if (IS_ERR(dst)) {
err = PTR_ERR(dst);
dst = NULL;
-- 
1.8.3.1