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Subject: Re: [PATCH 1/1] net: ipv4: refine the logic for determining daddr
 in ip_queue_xmit.
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Harvey Yang <harvey.huawei.yang@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        James Morris <jmorris@namei.org>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Date: Mon, 14 Jan 2013 20:57:09 -0800
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On Tue, 2013-01-15 at 12:47 +0800, Harvey Yang wrote:
> The destination address daddr is faddr if source route option is set, otherwise it is inet_daddr. So use if-else to assign the value.
> 
> Signed-off-by: Harvey Yang <harvey.huawei.yang@gmail.com>
> ---
>  net/ipv4/ip_output.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 3e98ed2..22b738c 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -349,10 +349,10 @@ int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
>  		__be32 daddr;
>  
>  		/* Use correct destination address if we have options. */
> -		daddr = inet->inet_daddr;
>  		if (inet_opt && inet_opt->opt.srr)
>  			daddr = inet_opt->opt.faddr;
> -
> +		else
> +			daddr = inet->inet_daddr;
>  		/* If this fails, retransmit mechanism of transport layer will
>  		 * keep trying until route appears or the connection times
>  		 * itself out.

Current code is faster, srr is not often used.