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Commit 79578621 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: implement cgroup_rm_cftypes() 



Implement cgroup_rm_cftypes() which removes an array of cftypes from a
subsystem.  It can be called whether the target subsys is attached or
not.  cgroup core will remove the specified file from all existing
cgroups.

This will be used to improve sub-subsys modularity and will be helpful
for unified hierarchy.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
parent 05ef1d7c

include/linux/cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -406,6 +406,7 @@ struct cgroup_scanner { 
};



int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);

int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);



int cgroup_is_removed(const struct cgroup *cgrp);

kernel/cgroup.c

+44 −10
Original line number Diff line number Diff line
@@ -2690,17 +2690,20 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys, 
	return error;

}



static int cgroup_add_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,

			    const struct cftype cfts[])

static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,

			      const struct cftype cfts[], bool is_add)

{

	const struct cftype *cft;

	int err, ret = 0;



	for (cft = cfts; cft->name[0] != '\0'; cft++) {

		if (is_add)

			err = cgroup_add_file(cgrp, subsys, cft);

		else

			err = cgroup_rm_file(cgrp, cft);

		if (err) {

			pr_warning("cgroup_add_files: failed to create %s, err=%d\n",

				   cft->name, err);

			pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n",

				   is_add ? "add" : "remove", cft->name, err);

			ret = err;

		}

	}
@@ -2724,7 +2727,7 @@ static void cgroup_cfts_prepare(void) 
}



static void cgroup_cfts_commit(struct cgroup_subsys *ss,

			       const struct cftype *cfts)

			       const struct cftype *cfts, bool is_add)

	__releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)

{

	LIST_HEAD(pending);
@@ -2750,7 +2753,7 @@ static void cgroup_cfts_commit(struct cgroup_subsys *ss, 
		mutex_lock(&inode->i_mutex);

		mutex_lock(&cgroup_mutex);

		if (!cgroup_is_removed(cgrp))

			cgroup_add_files(cgrp, ss, cfts);

			cgroup_addrm_files(cgrp, ss, cfts, is_add);

		mutex_unlock(&cgroup_mutex);

		mutex_unlock(&inode->i_mutex);
@@ -2786,12 +2789,43 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts) 
	cgroup_cfts_prepare();

	set->cfts = cfts;

	list_add_tail(&set->node, &ss->cftsets);

	cgroup_cfts_commit(ss, cfts);

	cgroup_cfts_commit(ss, cfts, true);



	return 0;

}

EXPORT_SYMBOL_GPL(cgroup_add_cftypes);



/**

 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem

 * @ss: target cgroup subsystem

 * @cfts: zero-length name terminated array of cftypes

 *

 * Unregister @cfts from @ss.  Files described by @cfts are removed from

 * all existing cgroups to which @ss is attached and all future cgroups

 * won't have them either.  This function can be called anytime whether @ss

 * is attached or not.

 *

 * Returns 0 on successful unregistration, -ENOENT if @cfts is not

 * registered with @ss.

 */

int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)

{

	struct cftype_set *set;



	cgroup_cfts_prepare();



	list_for_each_entry(set, &ss->cftsets, node) {

		if (set->cfts == cfts) {

			list_del_init(&set->node);

			cgroup_cfts_commit(ss, cfts, false);

			return 0;

		}

	}



	cgroup_cfts_commit(ss, NULL, false);

	return -ENOENT;

}



/**

 * cgroup_task_count - count the number of tasks in a cgroup.

 * @cgrp: the cgroup in question
@@ -3784,7 +3818,7 @@ static int cgroup_populate_dir(struct cgroup *cgrp) 
	int err;

	struct cgroup_subsys *ss;



	err = cgroup_add_files(cgrp, NULL, files);

	err = cgroup_addrm_files(cgrp, NULL, files, true);

	if (err < 0)

		return err;
@@ -3796,7 +3830,7 @@ static int cgroup_populate_dir(struct cgroup *cgrp) 
			return err;



		list_for_each_entry(set, &ss->cftsets, node)

			cgroup_add_files(cgrp, ss, set->cfts);

			cgroup_addrm_files(cgrp, ss, set->cfts, true);

	}



	/* This cgroup is ready now */