diff options
| author | Gang Yan <yangang@kylinos.cn> | 2026-04-20 19:19:23 +0300 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2026-04-23 14:20:17 +0300 |
| commit | fcf04b14334641f4b0b8647824480935e9416d52 (patch) | |
| tree | d47544f63428f1660e8622984a3191145c76f328 | |
| parent | 1cb36e252211506f51095fe7ced8286cc77b4c80 (diff) | |
| download | linux-fcf04b14334641f4b0b8647824480935e9416d52.tar.xz | |
mptcp: sync the msk->sndbuf at accept() time
On passive MPTCP connections, the msk sndbuf is not updated correctly.
The root cause is an order issue in the accept path:
- tcp_check_req() -> subflow_syn_recv_sock() -> mptcp_sk_clone_init()
calls __mptcp_propagate_sndbuf() to copy the ssk sndbuf into msk
- Later, tcp_child_process() -> tcp_init_transfer() ->
tcp_sndbuf_expand() grows the ssk sndbuf.
So __mptcp_propagate_sndbuf() runs before the ssk sndbuf has been
expanded and the msk ends up with a much smaller sndbuf than the
subflow:
MPTCP: msk->sndbuf:20480, msk->first->sndbuf:2626560
Fix this by moving the __mptcp_propagate_sndbuf() call from
mptcp_sk_clone_init() -- the ssk sndbuf is not yet finalized there -- to
__mptcp_propagate_sndbuf() at accept() time, when the ssk sndbuf has
been fully expanded by tcp_sndbuf_expand().
Fixes: 8005184fd1ca ("mptcp: refactor sndbuf auto-tuning")
Cc: stable@vger.kernel.org
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/602
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260420-net-mptcp-sync-sndbuf-accept-v1-1-e3523e3aeb44@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | net/mptcp/protocol.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index fbffd3a43fe8..718e910ff23f 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3594,7 +3594,6 @@ struct sock *mptcp_sk_clone_init(const struct sock *sk, * uses the correct data */ mptcp_copy_inaddrs(nsk, ssk); - __mptcp_propagate_sndbuf(nsk, ssk); mptcp_rcv_space_init(msk, ssk); msk->rcvq_space.time = mptcp_stamp(); @@ -4252,6 +4251,7 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock, mptcp_graft_subflows(newsk); mptcp_rps_record_subflows(msk); + __mptcp_propagate_sndbuf(newsk, mptcp_subflow_tcp_sock(subflow)); /* Do late cleanup for the first subflow as necessary. Also * deal with bad peers not doing a complete shutdown. |