mptcp: Skip unnecessary skb extension allocation for bare acks

Bare TCP ack skbs are freed right after MPTCP sees them, so the work to
allocate, zero, and populate the MPTCP skb extension is wasted. Detect
these skbs and do not add skb extensions to them.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mat Martineau 2020-07-28 15:12:08 -07:00 committed by David S. Miller
parent 067a0b3dc5
commit 06827b348b

View File

@ -868,15 +868,18 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
if (mp_opt.use_ack)
update_una(msk, &mp_opt);
/* Zero-length packets, like bare ACKs carrying a DATA_FIN, are
* dropped by the caller and not propagated to the MPTCP layer.
* Copy the DATA_FIN information now.
/* Zero-data-length packets are dropped by the caller and not
* propagated to the MPTCP layer, so the skb extension does not
* need to be allocated or populated. DATA_FIN information, if
* present, needs to be updated here before the skb is freed.
*/
if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
if (mp_opt.data_fin && mp_opt.data_len == 1 &&
mptcp_update_rcv_data_fin(msk, mp_opt.data_seq) &&
schedule_work(&msk->work))
sock_hold(subflow->conn);
return;
}
mpext = skb_ext_add(skb, SKB_EXT_MPTCP);