From a6f0459aadf1b41a9b9fae02006b1db024d60856 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 28 Oct 2025 12:57:59 +0100 Subject: [PATCH] mptcp: fix subflow rcvbuf adjust The mptcp PM can add subflow to the conn_list before tcp_init_transfer(). Calling tcp_rcvbuf_grow() on such subflow is not correct as later init will overwrite the update. Fix the issue calling tcp_rcvbuf_grow() only after init buffer initialization. Fixes: e118cdc34dd1 ("mptcp: rcvbuf auto-tuning improvement") Signed-off-by: Paolo Abeni Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251028-net-tcp-recv-autotune-v3-1-74b43ba4c84c@kernel.org Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 0292162a14ee..a8a3bdf95543 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2051,6 +2051,7 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied) msk->rcvq_space.space = msk->rcvq_space.copied; if (mptcp_rcvbuf_grow(sk)) { + int copied = msk->rcvq_space.copied; /* Make subflows follow along. If we do not do this, we * get drops at subflow level if skbs can't be moved to @@ -2063,8 +2064,11 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied) ssk = mptcp_subflow_tcp_sock(subflow); slow = lock_sock_fast(ssk); - tcp_sk(ssk)->rcvq_space.space = msk->rcvq_space.copied; - tcp_rcvbuf_grow(ssk); + /* subflows can be added before tcp_init_transfer() */ + if (tcp_sk(ssk)->rcvq_space.space) { + tcp_sk(ssk)->rcvq_space.space = copied; + tcp_rcvbuf_grow(ssk); + } unlock_sock_fast(ssk, slow); } } -- 2.47.3