Commit cc4de047 authored May 08, 2020 by Kelly Littlepage Committed by Jakub Kicinski May 08, 2020

net: tcp: fix rx timestamp behavior for tcp_recvmsg



The stated intent of the original commit is to is to "return the timestamp
corresponding to the highest sequence number data returned." The current
implementation returns the timestamp for the last byte of the last fully
read skb, which is not necessarily the last byte in the recv buffer. This
patch converts behavior to the original definition, and to the behavior of
the previous draft versions of commit 98aaa913 ("tcp: Extend
SOF_TIMESTAMPING_RX_SOFTWARE to TCP recvmsg") which also match this
behavior.

Fixes: 98aaa913 ("tcp: Extend SOF_TIMESTAMPING_RX_SOFTWARE to TCP recvmsg")
Co-developed-by: Iris Liu <iris@onechronos.com>
Signed-off-by: Iris Liu <iris@onechronos.com>
Signed-off-by: Kelly Littlepage <kelly@onechronos.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent dd912306

net/ipv4/tcp.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2154,13 +2154,15 @@ skip_copy:
		tp->urg_data = 0;
		tcp_fast_path_check(sk);
		}
		if (used + offset < skb->len)
		continue;

		if (TCP_SKB_CB(skb)->has_rxtstamp) {
		tcp_update_recv_tstamps(skb, &tss);
		cmsg_flags \|= 2;
		}

		if (used + offset < skb->len)
		continue;

		if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
		goto found_fin_ok;
		if (!(flags & MSG_PEEK))

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