mptcp: always graft subflow socket to parent

Currently, incoming subflows link to the parent socket,
while outgoing ones link to a per subflow socket. The latter
is not really needed, except at the initial connect() time and
for the first subflow.

Always graft the outgoing subflow to the parent socket and
free the unneeded ones early.

This allows some code cleanup, reduces the amount of memory
used and will simplify the next patch

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f998a077c7dd04a319c1de11cb37a07fdbb3eb88..c5c80f9253832b4ecaf9ddfaa48205d340e9e213 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -114,11 +114,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk)
        list_add(&subflow->node, &msk->conn_list);
        sock_hold(ssock->sk);
        subflow->request_mptcp = 1;
-
-       /* accept() will wait on first subflow sk_wq, and we always wakes up
-        * via msk->sk_socket
-        */
-       RCU_INIT_POINTER(msk->first->sk_wq, &sk->sk_socket->wq);
+       mptcp_sock_graft(msk->first, sk->sk_socket);
 
        return 0;
 }
@@ -2116,9 +2112,6 @@ static struct sock *mptcp_subflow_get_retrans(const struct mptcp_sock *msk)
 void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
                       struct mptcp_subflow_context *subflow)
 {
-       bool dispose_socket = false;
-       struct socket *sock;
-
        list_del(&subflow->node);
 
        lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
@@ -2126,11 +2119,8 @@ void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
        /* if we are invoked by the msk cleanup code, the subflow is
         * already orphaned
         */
-       sock = ssk->sk_socket;
-       if (sock) {
-               dispose_socket = sock != sk->sk_socket;
+       if (ssk->sk_socket)
                sock_orphan(ssk);
-       }
 
        subflow->disposable = 1;
 
@@ -2148,8 +2138,6 @@ void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
                __sock_put(ssk);
        }
        release_sock(ssk);
-       if (dispose_socket)
-               iput(SOCK_INODE(sock));
 
        sock_put(ssk);
 }
@@ -2536,6 +2524,12 @@ static void __mptcp_destroy_sock(struct sock *sk)
 
        pr_debug("msk=%p", msk);
 
+       /* dispose the ancillatory tcp socket, if any */
+       if (msk->subflow) {
+               iput(SOCK_INODE(msk->subflow));
+               msk->subflow = NULL;
+       }
+
        /* be sure to always acquire the join list lock, to sync vs
         * mptcp_finish_join().
         */
@@ -2586,20 +2580,10 @@ cleanup:
        inet_csk(sk)->icsk_mtup.probe_timestamp = tcp_jiffies32;
        list_for_each_entry(subflow, &mptcp_sk(sk)->conn_list, node) {
                struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-               bool slow, dispose_socket;
-               struct socket *sock;
+               bool slow = lock_sock_fast(ssk);
 
-               slow = lock_sock_fast(ssk);
-               sock = ssk->sk_socket;
-               dispose_socket = sock && sock != sk->sk_socket;
                sock_orphan(ssk);
                unlock_sock_fast(ssk, slow);
-
-               /* for the outgoing subflows we additionally need to free
-                * the associated socket
-                */
-               if (dispose_socket)
-                       iput(SOCK_INODE(sock));
        }
        sock_orphan(sk);
 
@@ -3041,7 +3025,7 @@ void mptcp_finish_connect(struct sock *ssk)
        mptcp_rcv_space_init(msk, ssk);
 }
 
-static void mptcp_sock_graft(struct sock *sk, struct socket *parent)
+void mptcp_sock_graft(struct sock *sk, struct socket *parent)
 {
        write_lock_bh(&sk->sk_callback_lock);
        rcu_assign_pointer(sk->sk_wq, &parent->wq);

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index d6400ad2d61568a01862e74552877a0e154a5a9b..65d200a1072bfc95365815b810d585fb11ed3c24 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -473,6 +473,7 @@ void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how);
 void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
                       struct mptcp_subflow_context *subflow);
 void mptcp_subflow_reset(struct sock *ssk);
+void mptcp_sock_graft(struct sock *sk, struct socket *parent);
 
 /* called with sk socket lock held */
 int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 278cbe3e539ea1a4a4bb0603c1761bb42df3396f..22313710d7696057bde0db48ea185e26f62f5a13 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1159,6 +1159,9 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
        if (err && err != -EINPROGRESS)
                goto failed_unlink;
 
+       /* discard the subflow socket */
+       mptcp_sock_graft(ssk, sk->sk_socket);
+       iput(SOCK_INODE(sf));
        return err;
 
 failed_unlink: