netdev - [PATCH net-next] tcp: handle EOR and FIN conditions the same in tcp_tso_should

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Date:   Mon, 10 Dec 2018 06:10:02 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Neal Cardwell <ncardwell@...gle.com>,
        Soheil Hassas Yeganeh <soheil@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next] tcp: handle EOR and FIN conditions the same in tcp_tso_should_defer()

In commit f9bfe4e6a9d0 ("tcp: lack of available data can also cause
TSO defer") we moved the test in tcp_tso_should_defer() for packets
with a FIN flag, and we mentioned that the same would be done
later for EOR flag.

Both flags should be handled at the same time, after all other
heuristics have been considered. They both mean that no more bytes
can be added to this skb by an application.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp_output.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index c31badfee806a70d5af6dc033cf9155adb1f9375..730bc44dbad9363814705b28c2f91a2253d91207 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1947,10 +1947,6 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 	if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
 		goto send_now;
 
-	/* If this packet won't get more data, do not wait. */
-	if (TCP_SKB_CB(skb)->eor)
-		goto send_now;
-
 	win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor);
 	if (win_divisor) {
 		u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache);
@@ -1999,7 +1995,8 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 	}
 
 	/* If this packet won't get more data, do not wait. */
-	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
+	if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) ||
+	    TCP_SKB_CB(skb)->eor)
 		goto send_now;
 
 	return true;
-- 
2.20.0.rc2.403.gdbc3b29805-goog