[PATCH v6 0/3] cgroups: add pids subsystem

[Aleksa Sarai <cyphar@cyphar.com>]

This is a revised version of the pids v5 patchset, modified to deal with
several stylistic and correctness issues put forward by Tejun Heo. The
main changes include:

* Add bitmask filtering of for_each_subsys() in the form of
  for_each_subsys_which().

* Revert all succeeded can_fork() callbacks if any one of them fails
  inside cgroup_can_fork().

* Move revert/reapply code to a reapply_fork() callback provided by each
  cgroup controller. It is only run if the association for the specific
  subsystem changed during the interlude between cgroup_can_fork() and
  cgroup_post_fork().

* Pass an opaque pointer between cgroup_*_fork(), which holds the
  "current" task css_set. The css_set is pinned by bumping the refcount
  in cgroup_can_fork() and later unpinned in
  cgroup_{cancel,post}_fork().

* A whole bunch of userland API and stylistic fixes.

Aleksa Sarai (3):
  cgroups: use bitmask to filter for_each_subsys
  cgroups: allow a cgroup subsystem to reject a fork
  cgroups: add a pids subsystem

 include/linux/cgroup.h        |  13 +-
 include/linux/cgroup_subsys.h |   4 +
 init/Kconfig                  |  11 ++
 kernel/Makefile               |   1 +
 kernel/cgroup.c               | 132 +++++++++++++++---
 kernel/cgroup_pids.c          | 301 ++++++++++++++++++++++++++++++++++++++++++
 kernel/fork.c                 |  18 ++-
 7 files changed, 459 insertions(+), 21 deletions(-)
 create mode 100644 kernel/cgroup_pids.c

-- 
2.3.2