[RFC] Network namespaces a path to mergable code.

[ebiederm@xmission.com (Eric W. Biederman)]

Thinking about this I am going to suggest a slightly different direction
for get a patchset we can merge.

First we concentrate on the fundamentals.
- How we mark a device as belonging to a specific network namespace.
- How we mark a socket as belonging to a specific network namespace.

As part of the fundamentals we add a patch to the generic socket code
that by default will disable it for protocol families that do not indicate
support for handling network namespaces, on a non-default network namespace.

I think that gives us a path that will allow us to convert the network stack
one protocol family at a time instead of in one big lump.

Stubbing off the sysfs and sysctl interfaces in the first round for the
non-default namespaces as you have done should be good enough.

The reason for the suggestion is that most of the work for the protocol
stacks ipv4 ipv6 af_packet af_unix is largely noise, and simple
replacement without real design work happening.  Mostly it is just
tweaking the code to remove global variables, and doing a couple
lookups.

Eric