Messages in this thread | | | Subject | Re: [PATCH] tcp: do not update snd_una if it is same with ack_seq | From | Joe Perches <> | Date | Sat, 03 Nov 2018 10:04:03 -0700 |
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On Sun, 2018-11-04 at 00:54 +0800, Yafang Shao wrote: > 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. [] > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c [] > @@ -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) {
stylistic nit:
While the precedence is correct in any case, perhaps adding parentheses around flag & FLAG_SND_UNA_ADVANCED would make it more obvious.
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