The nipa CI is reporting frequent failures in the mptcp_connect self-tests. In the failing scenarios (TCP -> MPTCP) the involved sockets are actually plain TCP ones, as fallback for passive socket at 2whs time cause the MPTCP listener to actually create a TCP socket. The transfer is stuck due to the receiver buffer being zero. With the stronger check in place, tcp_clamp_window() can be invoked while the TCP socket has sk_rmem_alloc == 0, and the receive buffer will be zeroed, too. Pass to tcp_clamp_window() even the current skb truesize, so that such helper could compute and use the actual limit enforced by the stack. Fixes: 1d2fbaad7cd8 ("tcp: stronger sk_rcvbuf checks") Signed-off-by: Paolo Abeni --- net/ipv4/tcp_input.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 672cbfbdcec1..c98de02a3c57 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -610,24 +610,24 @@ static void tcp_init_buffer_space(struct sock *sk) } /* 4. Recalculate window clamp after socket hit its memory bounds. */ -static void tcp_clamp_window(struct sock *sk) +static void tcp_clamp_window(struct sock *sk, int truesize) { struct tcp_sock *tp = tcp_sk(sk); struct inet_connection_sock *icsk = inet_csk(sk); struct net *net = sock_net(sk); - int rmem2; + int rmem2, needed; icsk->icsk_ack.quick = 0; rmem2 = READ_ONCE(net->ipv4.sysctl_tcp_rmem[2]); + needed = atomic_read(&sk->sk_rmem_alloc) + truesize; if (sk->sk_rcvbuf < rmem2 && !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) && !tcp_under_memory_pressure(sk) && sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)) { - WRITE_ONCE(sk->sk_rcvbuf, - min(atomic_read(&sk->sk_rmem_alloc), rmem2)); + WRITE_ONCE(sk->sk_rcvbuf, min(needed, rmem2)); } - if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) + if (needed > sk->sk_rcvbuf) tp->rcv_ssthresh = min(tp->window_clamp, 2U * tp->advmss); } @@ -5552,7 +5552,7 @@ static int tcp_prune_queue(struct sock *sk, const struct sk_buff *in_skb) NET_INC_STATS(sock_net(sk), LINUX_MIB_PRUNECALLED); if (!tcp_can_ingest(sk, in_skb)) - tcp_clamp_window(sk); + tcp_clamp_window(sk, in_skb->truesize); else if (tcp_under_memory_pressure(sk)) tcp_adjust_rcv_ssthresh(sk); -- 2.50.0