From: Yafang Shao <laoar.shao@gmail.com>
To: davem@davemloft.net, edumazet@google.com
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Yafang Shao <laoar.shao@gmail.com>
Subject: [PATCH] tcp: do not update snd_una if it is same with ack_seq
Date: Sun, 4 Nov 2018 00:54:31 +0800 [thread overview]
Message-ID: <1541264071-9905-1-git-send-email-laoar.shao@gmail.com> (raw)
In the slow path, TCP_SKB_SB(skb)->ack_seq may be same with tp->snd_una,
and under this condition we don't need to update the snd_una.
Furthermore, tcp_ack_update_window() is only called in slow path,
so introducing this check won't affect the fast path processing.
By the way, '&' is a little faster than '-', so I replaced after() with
"flag & FLAG_SND_UNA_ADVANCED".
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
net/ipv4/tcp_input.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 2868ef2..db5a6b7 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3376,7 +3376,8 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32
}
}
- tcp_snd_una_update(tp, ack);
+ if (after(ack, tp->snd_una))
+ tcp_snd_una_update(tp, ack);
return flag;
}
@@ -3610,7 +3611,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (flag & FLAG_UPDATE_TS_RECENT)
tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
- if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) {
+ if (!(flag & FLAG_SLOWPATH) && flag & FLAG_SND_UNA_ADVANCED) {
/* Window is constant, pure forward advance.
* No more checks are required.
* Note, we use the fact that SND.UNA>=SND.WL2.
--
1.8.3.1
next reply other threads:[~2018-11-03 16:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-03 16:54 Yafang Shao [this message]
2018-11-03 17:04 ` [PATCH] tcp: do not update snd_una if it is same with ack_seq Joe Perches
2018-11-04 1:27 ` Yafang Shao
2018-11-04 0:40 ` Eric Dumazet
2018-11-04 1:26 ` Yafang Shao
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