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Commit 217fc829 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by Greg Kroah-Hartman
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tcp: inherit timestamp on mtu probe 

[ Upstream commit 888a5c53c0d8be6e98bc85b677f179f77a647873 ]

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: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9e208ccf

net/ipv4/tcp_output.c

+2 −1
Original line number Diff line number Diff line
@@ -1943,7 +1943,7 @@ 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;
@@ -2066,6 +2066,7 @@ 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 {