From: Paolo Abeni Date: Tue, 28 Oct 2025 08:16:54 +0000 (+0100) Subject: mptcp: restore window probe X-Git-Tag: v6.18-rc4~24^2~10^2~1 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a824084b98d8a1dbd6e85d0842a8eb5e73467f59;p=thirdparty%2Fkernel%2Fstable.git mptcp: restore window probe Since commit 72377ab2d671 ("mptcp: more conservative check for zero probes") the MPTCP-level zero window probe check is always disabled, as the TCP-level write queue always contains at least the newly allocated skb. Refine the relevant check tacking in account that the above condition and that such skb can have zero length. Fixes: 72377ab2d671 ("mptcp: more conservative check for zero probes") Cc: stable@vger.kernel.org Reported-by: Geliang Tang Closes: https://lore.kernel.org/d0a814c364e744ca6b836ccd5b6e9146882e8d42.camel@kernel.org Reviewed-by: Mat Martineau Signed-off-by: Paolo Abeni Tested-by: Geliang Tang Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251028-net-mptcp-send-timeout-v1-3-38ffff5a9ec8@kernel.org Signed-off-by: Jakub Kicinski --- diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2535788569ab..5d8714adae6c 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1299,7 +1299,12 @@ alloc_skb: if (copy == 0) { u64 snd_una = READ_ONCE(msk->snd_una); - if (snd_una != msk->snd_nxt || tcp_write_queue_tail(ssk)) { + /* No need for zero probe if there are any data pending + * either at the msk or ssk level; skb is the current write + * queue tail and can be empty at this point. + */ + if (snd_una != msk->snd_nxt || skb->len || + skb != tcp_send_head(ssk)) { tcp_remove_empty_skb(ssk); return 0; }