When cleaning up unaccepted mptcp socket still laying inside
the listener queue at listener close time, such sockets will
go through a regular close, waiting for a timeout before
shutting down the subflows.

There is no need to keep the kernel resources in use for
such a possibly long time: short-circuit to fast-close.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 net/mptcp/protocol.c | 7 +++++--
 net/mptcp/subflow.c  | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b867e3eec5b9..f742d558a1b8 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2977,10 +2977,13 @@ bool __mptcp_close(struct sock *sk, long timeout)
 		goto cleanup;
 	}
 
-	if (mptcp_check_readable(msk)) {
-		/* the msk has read data, do the MPTCP equivalent of TCP reset */
+	if (mptcp_check_readable(msk) || timeout < 0) {
+		/* If the msk has read data, or the caller explicitly ask it,
+		 * do the MPTCP equivalent of TCP reset, aka MTCP fastclose
+		 */
 		inet_sk_state_store(sk, TCP_CLOSE);
 		mptcp_do_fastclose(sk);
+		timeout = 0;
 	} else if (mptcp_close_state(sk)) {
 		__mptcp_wr_shutdown(sk);
 	}
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 6f198d6e1b22..a1f8bb745c1b 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1856,7 +1856,7 @@ void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_s
 		if (msk->first)
 			sock_hold(msk->first);
 
-		do_cancel_work = __mptcp_close(sk, 0);
+		do_cancel_work = __mptcp_close(sk, -1);
 		release_sock(sk);
 		if (do_cancel_work) {
 			/* lockdep will report a false positive ABBA deadlock
-- 
2.39.0

On 17/01/2023 08:36, Paolo Abeni wrote:
> When cleaning up unaccepted mptcp socket still laying inside
> the listener queue at listener close time, such sockets will
> go through a regular close, waiting for a timeout before
> shutting down the subflows.
> 
> There is no need to keep the kernel resources in use for
> such a possibly long time: short-circuit to fast-close.
> 
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
> ---
>  net/mptcp/protocol.c | 7 +++++--
>  net/mptcp/subflow.c  | 2 +-
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index b867e3eec5b9..f742d558a1b8 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -2977,10 +2977,13 @@ bool __mptcp_close(struct sock *sk, long timeout)
>  		goto cleanup;
>  	}
>  
> -	if (mptcp_check_readable(msk)) {
> -		/* the msk has read data, do the MPTCP equivalent of TCP reset */
> +	if (mptcp_check_readable(msk) || timeout < 0) {
> +		/* If the msk has read data, or the caller explicitly ask it,
> +		 * do the MPTCP equivalent of TCP reset, aka MTCP fastclose

(small typo here: s/MTCP/MPTCP/ -- I can fix it when applying the patch)

Cheers,
Matt
-- 
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