tree f7bf95a77788ee4ef2e8c07b5029232c6b48ecfe
parent 4b5c41aad4f6a4f9d723b8b5aea8c01264bd0763
author Eric W. Biederman <ebiederm@xmission.com> 1278985825 -0700
committer Eric W. Biederman <ebiederm@aristanetworks.com> 1312884014 -0500

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

By adding a flag to track when a pid namespace is dead, and
by testing that flag just before a process attaches to the
pid namespace, it is possible to guarantee that processes
never enter a dead pid namespace.  Currently sending SIGKILL
to all of the process in a dead pid namespace gives us this
guarantee but we need something a little strong to support
unsharing and joining a pid namespace.

To ensure that this does not slow down the common case I
tested this code with lat_proc from lm_bench and I did
not see any increase in the fork overhead.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>