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mptcp: use fastclose on more edge scenarios

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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: Matthieu Baerts <matthieu.baerts@tessares.net>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2022-09-30 08:59:32 -07:00 committed by David S. Miller
parent 69800e516e
commit d21f834855
1 changed files with 44 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
net/mptcp/protocol.c
View File

@ -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);
@ -2605,11 +2621,15 @@ 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)) {
inet_sk_state_store(sk, TCP_CLOSE);
__mptcp_destroy_sock(sk);
goto unlock;
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))
@ -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;