netdev - Re: [Patch net-next] ipv6: separate out procfs code from mcast.c

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Date:	Tue, 23 Apr 2013 13:26:27 -0400
From:	David Stevens <dlstevens@...ibm.com>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	Cong Wang <amwang@...hat.com>, David Miller <davem@...emloft.net>,
	netdev@...r.kernel.org, netdev-owner@...r.kernel.org,
	yoshfuji@...ux-ipv6.org
Subject: Re: [Patch net-next] ipv6: separate out procfs code from mcast.c

netdev-owner@...r.kernel.org wrote on 04/23/2013 08:33:57 AM:

> From: Bjørn Mork <bjorn@...k.no>
 
> Cong Wang <amwang@...hat.com> writes:

> I note that vxlan_init_net requires a successful sock_create_kern().
> That implies a request_module("net-pf-...") followed by try_module_get.
> 
> So if the sock_create_kern(PF_INET6, ..) succeeds then you *know* you
> have IPv6. If it fails with -EAFNOSUPPORT, then you could fall back to
> sock_create_kern(PF_INET, ..) and set a flag indicating that runtime
> IPv6 support is disabled.  Then use this flag to allow/deny configuring
> any IPv6 destinations.

BTW, another thing I thought of after I sent my patch comments -- you
also need to consider the state of net.ipv6.bindv6only. When v6 is
enabled, you use one socket for v4 and v6, but if bindv6only=1, you
actually need a separate socket for v4 receives. If you want to support
both v4 and v6 with bindv6only=1, you need two sockets. Or even if you
want to support v4-only VXLAN and the sysadmin has set bindv6only=1.

                                                                +-DLS

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