Commit dccf4617 authored by Matthieu Baerts (NGI0)'s avatar Matthieu Baerts (NGI0) Committed by Jakub Kicinski
Browse files

mptcp: only reset subflow errors when propagated 



Some subflow socket errors need to be reported to the MPTCP socket: the
initial subflow connect (MP_CAPABLE), and the ones from the fallback
sockets. The others are not propagated.

The issue is that sock_error() was used to retrieve the error, which was
also resetting the sk_err field. Because of that, when notifying the
userspace about subflow close events later on from the MPTCP worker, the
ssk->sk_err field was always 0.

Now, the error (sk_err) is only reset when propagating it to the msk.

Fixes: 15cc1045 ("mptcp: deliver ssk errors to msk")
Cc: stable@vger.kernel.org
Reviewed-by: default avatarGeliang Tang <geliang@kernel.org>
Signed-off-by: default avatarMatthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-3-7f71e1bc4feb@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8467458d

net/mptcp/protocol.c

+5 −4
Original line number Diff line number Diff line
@@ -821,11 +821,8 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) 


static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk)

{

	int err = sock_error(ssk);

	int ssk_state;



	if (!err)

		return false;

	int err;



	/* only propagate errors on fallen-back sockets or

	 * on MPC connect
@@ -833,6 +830,10 @@ static bool __mptcp_subflow_error_report(struct sock *sk, struct sock *ssk) 
	if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(mptcp_sk(sk)))

		return false;



	err = sock_error(ssk);

	if (!err)

		return false;



	/* We need to propagate only transition to CLOSE state.

	 * Orphaned socket will see such state change via

	 * subflow_sched_work_if_closed() and that path will properly