mptcp: avoid unneeded indirection in mptcp_stream_accept()

We are going to remove the first subflow socket soon, so avoid
the additional indirection at accept() time. Instead access
directly the first subflow sock, and update mptcp_accept() to
operate on it. This allows dropping a duplicated check in
mptcp_accept().

No functional changes intended.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e89d1bf..e5ebd17 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3174,25 +3174,17 @@ void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk)
        WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
 }
 
-static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
+static struct sock *mptcp_accept(struct sock *ssk, int flags, int *err,
                                 bool kern)
 {
-       struct mptcp_sock *msk = mptcp_sk(sk);
-       struct socket *listener;
        struct sock *newsk;
 
-       listener = READ_ONCE(msk->subflow);
-       if (WARN_ON_ONCE(!listener)) {
-               *err = -EINVAL;
-               return NULL;
-       }
-
-       pr_debug("msk=%p, listener=%p", msk, mptcp_subflow_ctx(listener->sk));
-       newsk = inet_csk_accept(listener->sk, flags, err, kern);
+       pr_debug("ssk=%p, listener=%p", ssk, mptcp_subflow_ctx(ssk));
+       newsk = inet_csk_accept(ssk, flags, err, kern);
        if (!newsk)
                return NULL;
 
-       pr_debug("msk=%p, subflow is mptcp=%d", msk, sk_is_mptcp(newsk));
+       pr_debug("newsk=%p, subflow is mptcp=%d", newsk, sk_is_mptcp(newsk));
        if (sk_is_mptcp(newsk)) {
                struct mptcp_subflow_context *subflow;
                struct sock *new_mptcp_sock;
@@ -3209,9 +3201,9 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
                }
 
                newsk = new_mptcp_sock;
-               MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
+               MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
        } else {
-               MPTCP_INC_STATS(sock_net(sk),
+               MPTCP_INC_STATS(sock_net(ssk),
                                MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
        }
 
@@ -3761,8 +3753,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
                               int flags, bool kern)
 {
        struct mptcp_sock *msk = mptcp_sk(sock->sk);
-       struct socket *ssock;
-       struct sock *newsk;
+       struct sock *ssk, *newsk;
        int err;
 
        pr_debug("msk=%p", msk);
@@ -3770,11 +3761,11 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
        /* Buggy applications can call accept on socket states other then LISTEN
         * but no need to allocate the first subflow just to error out.
         */
-       ssock = READ_ONCE(msk->subflow);
-       if (!ssock)
+       ssk = READ_ONCE(msk->first);
+       if (!ssk)
                return -EINVAL;
 
-       newsk = mptcp_accept(sock->sk, flags, &err, kern);
+       newsk = mptcp_accept(ssk, flags, &err, kern);
        if (!newsk)
                return err;