netdev - Re: linux kernel's IPV6_MULTICAST_HOPS default is 64; should be 1?

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Message-Id: <20100504.005757.97355845.davem@davemloft.net>
Date:	Tue, 04 May 2010 00:57:57 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dlstevens@...ibm.com
Cc:	enh@...gle.com, brian.haley@...com, netdev@...r.kernel.org,
	netdev-owner@...r.kernel.org
Subject: Re: linux kernel's IPV6_MULTICAST_HOPS default is 64; should be 1?


From: David Stevens <dlstevens@...ibm.com>
Date: Tue, 4 May 2010 00:48:46 -0700

> It's set to -1 by default, but the common code for unicast and
> multicast in getsockopt is falling through to use the dst_entry.
> 
> I believe (though I haven't actually tried it recently) it actually
> uses "1" for the default value for multicast;

It doesn't, all of the uses in the ipv6 stack say something like:

	if (multicast)
		hlimit = np->mcast_hops;
	else
		hlimit = np->hop_limit;
	if (hlimit < 0)
		hlimit = ip6_dst_hoplimit(dst);

Therefore, the change suggested by Elliot and which I committed is the
way to get the correct behavior and fix this.
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