l2tp: create tunnel sockets in the right namespace
l2tp: create tunnel sockets in the right namespace

When creating unmanaged tunnel sockets we should honour the network namespace
passed to l2tp_tunnel_create.  Furthermore, unmanaged tunnel sockets should
not hold a reference to the network namespace lest they accidentally keep
alive a namespace which should otherwise have been released.

Unmanaged tunnel sockets now drop their namespace reference via sk_change_net,
and are released in a new pernet exit callback, l2tp_exit_net.

Signed-off-by: Tom Parkin <ea112d67cab4b46373b4d6536b035de78635308d@katalix.com>
Signed-off-by: James Chapman <d87d459960487ecb1b999dfc309f5d5f521df082@katalix.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas