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Commit 073219e9 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: clean up cgroup_subsys names and initialization 



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.

v2: Rebased on top of fe1217c4 ("net: net_cls: move cgroupfs
    classid handling into core").

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Acked-by: default avatar"David S. Miller" <davem@davemloft.net>
Acked-by: default avatar"Rafael J. Wysocki" <rjw@rjwysocki.net>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarAristeu Rozanski <aris@redhat.com>
Acked-by: default avatarIngo Molnar <mingo@redhat.com>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Thomas Graf <tgraf@suug.ch>
parent 3ed80a62

block/blk-cgroup.c

+3 −5
Original line number Diff line number Diff line
@@ -906,16 +906,14 @@ static int blkcg_can_attach(struct cgroup_subsys_state *css, 
	return ret;

}



struct cgroup_subsys blkio_subsys = {

	.name = "blkio",

struct cgroup_subsys blkio_cgrp_subsys = {

	.css_alloc = blkcg_css_alloc,

	.css_offline = blkcg_css_offline,

	.css_free = blkcg_css_free,

	.can_attach = blkcg_can_attach,

	.subsys_id = blkio_subsys_id,

	.base_cftypes = blkcg_files,

};

EXPORT_SYMBOL_GPL(blkio_subsys);

EXPORT_SYMBOL_GPL(blkio_cgrp_subsys);



/**

 * blkcg_activate_policy - activate a blkcg policy on a request_queue
@@ -1105,7 +1103,7 @@ int blkcg_policy_register(struct blkcg_policy *pol) 


	/* everything is in place, add intf files for the new policy */

	if (pol->cftypes)

		WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes));

		WARN_ON(cgroup_add_cftypes(&blkio_cgrp_subsys, pol->cftypes));

	ret = 0;

out_unlock:

	mutex_unlock(&blkcg_pol_mutex);

block/blk-cgroup.h

+1 −1
Original line number Diff line number Diff line
@@ -186,7 +186,7 @@ static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css) 


static inline struct blkcg *task_blkcg(struct task_struct *tsk)

{

	return css_to_blkcg(task_css(tsk, blkio_subsys_id));

	return css_to_blkcg(task_css(tsk, blkio_cgrp_id));

}



static inline struct blkcg *bio_blkcg(struct bio *bio)

fs/bio.c

+1 −1
Original line number Diff line number Diff line
@@ -1965,7 +1965,7 @@ int bio_associate_current(struct bio *bio) 


	/* associate blkcg if exists */

	rcu_read_lock();

	css = task_css(current, blkio_subsys_id);

	css = task_css(current, blkio_cgrp_id);

	if (css && css_tryget(css))

		bio->bi_css = css;

	rcu_read_unlock();

include/linux/cgroup.h

+4 −3
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ extern int cgroupstats_build(struct cgroupstats *stats, 
extern int proc_cgroup_show(struct seq_file *, void *);



/* define the enumeration of all cgroup subsystems */

#define SUBSYS(_x) _x ## _subsys_id,

#define SUBSYS(_x) _x ## _cgrp_id,

enum cgroup_subsys_id {

#include <linux/cgroup_subsys.h>

	CGROUP_SUBSYS_COUNT,
@@ -573,7 +573,6 @@ struct cgroup_subsys { 
		     struct task_struct *task);

	void (*bind)(struct cgroup_subsys_state *root_css);



	int subsys_id;

	int disabled;

	int early_init;
@@ -592,6 +591,8 @@ struct cgroup_subsys { 
	bool broken_hierarchy;

	bool warned_broken_hierarchy;



	/* the following two fields are initialized automtically during boot */

	int subsys_id;

#define MAX_CGROUP_TYPE_NAMELEN 32

	const char *name;
@@ -606,7 +607,7 @@ struct cgroup_subsys { 
	struct cftype_set base_cftset;

};



#define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys;

#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;

#include <linux/cgroup_subsys.h>

#undef SUBSYS

include/linux/cgroup_subsys.h

+3 −3
Original line number Diff line number Diff line
@@ -12,7 +12,7 @@ SUBSYS(debug) 
#endif



#if IS_ENABLED(CONFIG_CGROUP_SCHED)

SUBSYS(cpu_cgroup)

SUBSYS(cpu)

#endif



#if IS_ENABLED(CONFIG_CGROUP_CPUACCT)
@@ -20,7 +20,7 @@ SUBSYS(cpuacct) 
#endif



#if IS_ENABLED(CONFIG_MEMCG)

SUBSYS(mem_cgroup)

SUBSYS(memory)

#endif



#if IS_ENABLED(CONFIG_CGROUP_DEVICE)
@@ -40,7 +40,7 @@ SUBSYS(blkio) 
#endif



#if IS_ENABLED(CONFIG_CGROUP_PERF)

SUBSYS(perf)

SUBSYS(perf_event)

#endif



#if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)