[PATCH] tcp: provide tx timestamps for partial writes

[Soheil Hassas Yeganeh <soheil.kdev@gmail.com>]

From: Soheil Hassas Yeganeh <soheil@google.com>

For TCP sockets, tx timestamps are only captured when the user data
is successfully and fully written to the socket. In many cases,
however, TCP writes can be partial for which no timestamp is
collected.

Collect timestamps when the user data is partially copied into
the socket.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Martin KaFai Lau <kafai@fb.com>
---
 net/ipv4/tcp.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2e3807d..c207b16 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -992,8 +992,10 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
 	return copied;
 
 do_error:
-	if (copied)
+	if (copied) {
+		tcp_tx_timestamp(sk, sk->sk_tsflags, tcp_write_queue_tail(sk));
 		goto out;
+	}
 out_err:
 	/* make sure we wake any epoll edge trigger waiter */
 	if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 &&
@@ -1329,8 +1331,10 @@ int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 	}
 
 do_error:
-	if (copied + copied_syn)
+	if (copied + copied_syn) {
+		tcp_tx_timestamp(sk, sk->sk_tsflags, tcp_write_queue_tail(sk));
 		goto out;
+	}
 out_err:
 	err = sk_stream_error(sk, flags, err);
 	/* make sure we wake any epoll edge trigger waiter */
-- 
2.8.0.rc3.226.g39d4020