From: Paolo Abeni pabeni@redhat.com
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 geliang@kernel.org Closes: https://lore.kernel.org/d0a814c364e744ca6b836ccd5b6e9146882e8d42.camel@kerne... Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Tested-by: Geliang Tang geliang@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- net/mptcp/protocol.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index d6d1553fbd61..2feaf7afba49 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1290,7 +1290,12 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, 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; }