netdev - Re: [PATCH] fix pushed_seq in keepalive / zero window probe timer

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Date:	Mon, 22 Aug 2011 13:25:22 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Li Yu <raise.sail@...il.com>
Cc:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	davem@...emloft.net, ilpo.jarvinen@...sinki.fi
Subject: Re: [PATCH] fix pushed_seq in keepalive / zero window probe timer

Le lundi 22 août 2011 à 14:57 +0800, Li Yu a écrit :
> In tcp_write_wakeup(), we may split the probe segment since send window or mss is larger than it.
> so I think that we should update tp->pushed_seq after tcp_fragment(), is it right? thanks.
> 

I am not sure what you want to fix.

Fact is the skb has the TCPHDR_PSH, even if tcp_transmit_skb() (or
tcp_fragment()) is/are not able to clone/split it.


> Signed-off-by: Li Yu <raise.sail@...il.com>
> CC: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
> CC: David S. Miller <davem@...emloft.net>
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 882e0b0..659a71f 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -2784,9 +2784,6 @@ int tcp_write_wakeup(struct sock *sk)
>  		unsigned int mss = tcp_current_mss(sk);
>  		unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq;
>  
> -		if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq))
> -			tp->pushed_seq = TCP_SKB_CB(skb)->end_seq;
> -
>  		/* We are probing the opening of a window
>  		 * but the window size is != 0
>  		 * must have been a result SWS avoidance ( sender )
> @@ -2803,8 +2800,11 @@ int tcp_write_wakeup(struct sock *sk)
>  		TCP_SKB_CB(skb)->flags |= TCPHDR_PSH;
>  		TCP_SKB_CB(skb)->when = tcp_time_stamp;
>  		err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
> -		if (!err)
> +		if (!err) {
>  			tcp_event_new_data_sent(sk, skb);
> +			if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq))
> +				tp->pushed_seq = TCP_SKB_CB(skb)->end_seq;
> +		}
>  		return err;
>  	} else {
>  		if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF))
> 
> --
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