[PATCH 0/16] Pid namespaces

[sukadev at us.ibm.com]

Pavel Emelianov [xemul at openvz.org] wrote:
| This is "submition for inclusion" of hierarchical, not kconfig
| configurable, zero overheaded ;) pid namespaces.
| 
| The overall idea is the following:
| 
| The namespace are organized as a tree - once a task is cloned
| with CLONE_NEWPIDS (yes, I've also switched to it :) the new

Can you really clone() a pid namespace all by itself ?
copy_namespaces() has the following:


        if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC | CLONE_NEWUSER)))
                return 0;

doesn't it mean you cannot create a pid namespace using clone() unless
one of the above flags are also specified ?

unshare_nsproxy_namespaces() has the following correct check:

        if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
                               CLONE_NEWUSER | CLONE_NEWPIDS)))
                return 0;

BTW, why not use CLONE_NEWPID and drop the 'S' ? We don't have 'S' with
other namespaces.

Suka