tree 81b9fa941a3293f6d5fa4e32aa311988bb3bf985
parent 0a01f2cc390e10633a54f72c608cc3fe19a50c3d
author Eric W. Biederman <ebiederm@xmission.com> 1278985825 -0700
committer Eric W. Biederman <ebiederm@xmission.com> 1353333551 -0800

pidns: Don't allow new processes in a dead pid namespace.

Set nr_hashed to -1 just before we schedule the work to cleanup proc.
Test nr_hashed just before we hash a new pid and if nr_hashed is < 0
fail.

This guaranteees that processes never enter a pid namespaces after we
have cleaned up the state to support processes in a pid namespace.

Currently sending SIGKILL to all of the process in a pid namespace as
init exists gives us this guarantee but we need something a little
stronger to support unsharing and joining a pid namespace.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>