Commit d21f8348 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

mptcp: use fastclose on more edge scenarios 



Daire reported a user-space application hang-up when the
peer is forcibly closed before the data transfer completion.

The relevant application expects the peer to either
do an application-level clean shutdown or a transport-level
connection reset.

We can accommodate a such user by extending the fastclose
usage: at fd close time, if the msk socket has some unread
data, and at FIN_WAIT timeout.

Note that at MPTCP close time we must ensure that the TCP
subflows will reset: set the linger socket option to a suitable
value.

Reviewed-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 69800e51

net/mptcp/protocol.c

+44 −19
Original line number Diff line number Diff line
@@ -2313,8 +2313,14 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk, 


	lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);



	if (flags & MPTCP_CF_FASTCLOSE)

	if (flags & MPTCP_CF_FASTCLOSE) {

		/* be sure to force the tcp_disconnect() path,

		 * to generate the egress reset

		 */

		ssk->sk_lingertime = 0;

		sock_set_flag(ssk, SOCK_LINGER);

		subflow->send_fastclose = 1;

	}



	need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);

	if (!dispose_it) {
@@ -2577,6 +2583,16 @@ static void mptcp_mp_fail_no_response(struct mptcp_sock *msk) 
	mptcp_reset_timeout(msk, 0);

}



static void mptcp_do_fastclose(struct sock *sk)

{

	struct mptcp_subflow_context *subflow, *tmp;

	struct mptcp_sock *msk = mptcp_sk(sk);



	mptcp_for_each_subflow_safe(msk, subflow, tmp)

		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow),

				  subflow, MPTCP_CF_FASTCLOSE);

}



static void mptcp_worker(struct work_struct *work)

{

	struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
@@ -2605,12 +2621,16 @@ static void mptcp_worker(struct work_struct *work) 
	 * closed, but we need the msk around to reply to incoming DATA_FIN,

	 * even if it is orphaned and in FIN_WAIT2 state

	 */

	if (sock_flag(sk, SOCK_DEAD) &&

	    (mptcp_check_close_timeout(sk) || sk->sk_state == TCP_CLOSE)) {

	if (sock_flag(sk, SOCK_DEAD)) {

		if (mptcp_check_close_timeout(sk)) {

			inet_sk_state_store(sk, TCP_CLOSE);

			mptcp_do_fastclose(sk);

		}

		if (sk->sk_state == TCP_CLOSE) {

			__mptcp_destroy_sock(sk);

			goto unlock;

		}

	}



	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))

		__mptcp_close_subflow(msk);
@@ -2850,6 +2870,18 @@ static void __mptcp_destroy_sock(struct sock *sk) 
	sock_put(sk);

}



static __poll_t mptcp_check_readable(struct mptcp_sock *msk)

{

	/* Concurrent splices from sk_receive_queue into receive_queue will

	 * always show at least one non-empty queue when checked in this order.

	 */

	if (skb_queue_empty_lockless(&((struct sock *)msk)->sk_receive_queue) &&

	    skb_queue_empty_lockless(&msk->receive_queue))

		return 0;



	return EPOLLIN | EPOLLRDNORM;

}



bool __mptcp_close(struct sock *sk, long timeout)

{

	struct mptcp_subflow_context *subflow;
@@ -2863,8 +2895,13 @@ bool __mptcp_close(struct sock *sk, long timeout) 
		goto cleanup;

	}



	if (mptcp_close_state(sk))

	if (mptcp_check_readable(msk)) {

		/* the msk has read data, do the MPTCP equivalent of TCP reset */

		inet_sk_state_store(sk, TCP_CLOSE);

		mptcp_do_fastclose(sk);

	} else if (mptcp_close_state(sk)) {

		__mptcp_wr_shutdown(sk);

	}



	sk_stream_wait_close(sk, timeout);
@@ -3681,18 +3718,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, 
	return err;

}



static __poll_t mptcp_check_readable(struct mptcp_sock *msk)

{

	/* Concurrent splices from sk_receive_queue into receive_queue will

	 * always show at least one non-empty queue when checked in this order.

	 */

	if (skb_queue_empty_lockless(&((struct sock *)msk)->sk_receive_queue) &&

	    skb_queue_empty_lockless(&msk->receive_queue))

		return 0;



	return EPOLLIN | EPOLLRDNORM;

}



static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)

{

	struct sock *sk = (struct sock *)msk;