ipv4: Add helper inet_csk_update_pmtu().

This abstracts away the call to dst_ops->update_pmtu() so that we can
transparently handle the fact that, in the future, the dst itself can
be invalidated by the PMTU update (when we have non-host routes cached
in sockets).

So we try to rebuild the socket cached route after the method
invocation if necessary.

This isn't used by SCTP because it needs to cache dsts per-transport,
and thus will need it's own local version of this helper.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 291e7cee14e73a720331870ef41d9417c5b2f926..2cf44b4ed2e6cf1ad4aedbebb30c3b802c9bfa33 100644 (file)
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -337,4 +337,6 @@ extern int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
                                      char __user *optval, int __user *optlen);
 extern int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
                                      char __user *optval, unsigned int optlen);
+
+extern struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu);
 #endif /* _INET_CONNECTION_SOCK_H */

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 129ed8f74138d62bc495569ffbcc73eb5cd82537..683902fcc8ed746f431bd372a57cccdb694adb32 100644 (file)
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -161,17 +161,10 @@ static inline void dccp_do_pmtu_discovery(struct sock *sk,
        if (sk->sk_state == DCCP_LISTEN)
                return;
 
-       /* We don't check in the destentry if pmtu discovery is forbidden
-        * on this route. We just assume that no packet_to_big packets
-        * are send back when pmtu discovery is not active.
-        * There is a small race when the user changes this flag in the
-        * route, but I think that's acceptable.
-        */
-       if ((dst = __sk_dst_check(sk, 0)) == NULL)
+       dst = inet_csk_update_pmtu(sk, mtu);
+       if (!dst)
                return;
 
-       dst->ops->update_pmtu(dst, mtu);
-
        /* Something is about to be wrong... Remember soft error
         * for the case, if this connection will not able to recover.
         */

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 76825be3b64341635fd57a63efae5f40445fc646..200d2180937940505df6feab85c08cd128f68128 100644 (file)
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -803,3 +803,49 @@ int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
 }
 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
 #endif
+
+static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
+{
+       struct inet_sock *inet = inet_sk(sk);
+       struct ip_options_rcu *inet_opt;
+       __be32 daddr = inet->inet_daddr;
+       struct flowi4 *fl4;
+       struct rtable *rt;
+
+       rcu_read_lock();
+       inet_opt = rcu_dereference(inet->inet_opt);
+       if (inet_opt && inet_opt->opt.srr)
+               daddr = inet_opt->opt.faddr;
+       fl4 = &fl->u.ip4;
+       rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
+                                  inet->inet_saddr, inet->inet_dport,
+                                  inet->inet_sport, sk->sk_protocol,
+                                  RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
+       if (IS_ERR(rt))
+               rt = NULL;
+       if (rt)
+               sk_setup_caps(sk, &rt->dst);
+       rcu_read_unlock();
+
+       return &rt->dst;
+}
+
+struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
+{
+       struct dst_entry *dst = __sk_dst_check(sk, 0);
+       struct inet_sock *inet = inet_sk(sk);
+
+       if (!dst) {
+               dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
+               if (!dst)
+                       goto out;
+       }
+       dst->ops->update_pmtu(dst, mtu);
+
+       dst = __sk_dst_check(sk, 0);
+       if (!dst)
+               dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
+out:
+       return dst;
+}
+EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 7a0062cb4ed05a189c7ca775f35221097532dabe..b8e7e0595407a3e64a4f083f8d6d96ffd2b466ca 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -289,17 +289,10 @@ static void do_pmtu_discovery(struct sock *sk, const struct iphdr *iph, u32 mtu)
        if (sk->sk_state == TCP_LISTEN)
                return;
 
-       /* We don't check in the destentry if pmtu discovery is forbidden
-        * on this route. We just assume that no packet_to_big packets
-        * are send back when pmtu discovery is not active.
-        * There is a small race when the user changes this flag in the
-        * route, but I think that's acceptable.
-        */
-       if ((dst = __sk_dst_check(sk, 0)) == NULL)
+       dst = inet_csk_update_pmtu(sk, mtu);
+       if (!dst)
                return;
 
-       dst->ops->update_pmtu(dst, mtu);
-
        /* Something is about to be wrong... Remember soft error
         * for the case, if this connection will not able to recover.
         */