On Fri, Jan 17, 2014 at 01:11:54PM -0500, Tejun Heo wrote:

cgroup_subsys is a bit messier than it needs to be.

* The name of a subsys can be different from its internal identifier
  defined in cgroup_subsys.h.  Most subsystems use the matching name
  but three - cpu, memory and perf_event - use different ones.

* cgroup_subsys_id enums are postfixed with _subsys_id and each
  cgroup_subsys is postfixed with _subsys.  cgroup.h is widely
  included throughout various subsystems, it doesn't and shouldn't
  have claim on such generic names which don't have any qualifier
  indicating that they belong to cgroup.

* cgroup_subsys->subsys_id should always equal the matching
  cgroup_subsys_id enum; however, we require each controller to
  initialize it and then BUG if they don't match, which is a bit
  silly.

This patch cleans up cgroup_subsys names and initialization by doing
the followings.

* cgroup_subsys_id enums are now postfixed with _cgrp_id, and each
  cgroup_subsys with _cgrp_subsys.

* With the above, renaming subsys identifiers to match the userland
  visible names doesn't cause any naming conflicts.  All non-matching
  identifiers are renamed to match the official names.

  cpu_cgroup -> cpu
  mem_cgroup -> memory
  perf -> perf_event

* controllers no longer need to initialize ->subsys_id and ->name.
  They're generated in cgroup core and set automatically during boot.

* Redundant cgroup_subsys declarations removed.

* While updating BUG_ON()s in cgroup_init_early(), convert them to
  WARN()s.  BUGging that early during boot is stupid - the kernel
  can't print anything, even through serial console and the trap
  handler doesn't even link stack frame properly for back-tracing.

This patch doesn't introduce any behavior changes.

Signed-off-by: Tejun Heo <redacted>
Cc: Ingo Molnar <redacted>
Cc: Peter Zijlstra <redacted>
Cc: Li Zefan <redacted>
Cc: Johannes Weiner <redacted>
Cc: Michal Hocko <redacted>
Cc: Balbir Singh <redacted>
Cc: KAMEZAWA Hiroyuki <redacted>
Cc: Aristeu Rozanski <redacted>
Cc: Serge E. Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
Cc: "Rafael J. Wysocki" <redacted>
Cc: Vivek Goyal <redacted>
Cc: Neil Horman <redacted>
Cc: Thomas Graf <tgraf-G/eBtMaohhA@public.gmane.org>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>

For the netprio and net_cls bits
Acked-by: Neil Horman <redacted>