Commit 888a5c53 authored Aug 27, 2019 by Willem de Bruijn Committed by David S. Miller Aug 28, 2019

tcp: inherit timestamp on mtu probe

TCP associates tx timestamp requests with a byte in the bytestream.
If merging skbs in tcp_mtu_probe, migrate the tstamp request.

Similar to MSG_EOR, do not allow moving a timestamp from any segment
in the probe but the last. This to avoid merging multiple timestamps.

Tested with the packetdrill script at
https://github.com/wdebruij/packetdrill/commits/mtu_probe-1

Link: http://patchwork.ozlabs.org/patch/1143278/#2232897


Fixes: 4ed2d765 ("net-timestamp: TCP timestamping")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent dbf47a2a

net/ipv4/tcp_output.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2053,7 +2053,7 @@ static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len)
		if (len <= skb->len)
		break;

		if (unlikely(TCP_SKB_CB(skb)->eor))
		if (unlikely(TCP_SKB_CB(skb)->eor) \|\| tcp_has_tx_tstamp(skb))
		return false;

		len -= skb->len;
		@@ -2170,6 +2170,7 @@ static int tcp_mtu_probe(struct sock *sk)
		* we need to propagate it to the new skb.
		*/
		TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor;
		tcp_skb_collapse_tstamp(nskb, skb);
		tcp_unlink_write_queue(skb, sk);
		sk_wmem_free_skb(sk, skb);
		} else {

Admin message