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Subject: Re: [PATCH] net: Add default_advmss() methods to blackhole dst_ops
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Changli Gao <xiaosuo@gmail.com>
Cc: George Spelvin <linux@horizon.com>, David Miller <davem@davemloft.net>,
        linux-kernel@vger.kernel.org, netdev <netdev@vger.kernel.org>,
        Roland Dreier <roland@purestorage.com>
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Date: Fri, 18 Feb 2011 14:33:25 +0100
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Le vendredi 18 février 2011 à 21:29 +0800, Changli Gao a écrit :
> On Fri, Feb 18, 2011 at 9:24 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > Le vendredi 18 février 2011 à 21:16 +0800, Changli Gao a écrit :
> >
> >> I am wondering why magic number 256 is used here. Is there a special
> >> reason? Thanks.
> >>
> >
> > It really doesnt matter. SYN message will be dropped anyway.
> >
> > 256 happens to be the default value
> > of /proc/sys/net/ipv4/route/min_adv_mss
> >
> 
> Thanks for your explaining. IMHO, ip_rt_min_advmss is better than a
> magic number, here.
> 

I had this exact idea but found we need struct net pointer to get this
value, not provided in parameters, so I falled back to the 256 value.