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Commit 623f926b authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: reorganize css init / exit paths 



css (cgroup_subsys_state) lifetime management is about to be
restructured.  In prepartion, make the following mostly trivial
changes.

* init_cgroup_css() is renamed to init_css() so that it's consistent
  with other css handling functions.

* alloc_css_id(), online_css() and offline_css() updated to take @css
  instead of cgroups and subsys IDs.

This patch doesn't make any functional changes.

v2: v1 merged two for_each_root_subsys() loops in cgroup_create() but
    Li Zefan pointed out that it breaks error path.  Dropped.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 73e80ed8

kernel/cgroup.c

+23 −27
Original line number Diff line number Diff line
@@ -838,8 +838,7 @@ static struct backing_dev_info cgroup_backing_dev_info = { 
	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,

};



static int alloc_css_id(struct cgroup_subsys *ss,

			struct cgroup *parent, struct cgroup *child);

static int alloc_css_id(struct cgroup_subsys_state *child_css);



static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb)

{
@@ -4308,8 +4307,7 @@ static void css_release(struct percpu_ref *ref) 
	schedule_work(&css->destroy_work);

}



static void init_cgroup_css(struct cgroup_subsys_state *css,

			       struct cgroup_subsys *ss,

static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss,

		     struct cgroup *cgrp)

{

	css->cgroup = cgrp;
@@ -4327,9 +4325,9 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, 
}



/* invoke ->css_online() on a new CSS and mark it online if successful */

static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp)

static int online_css(struct cgroup_subsys_state *css)

{

	struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);

	struct cgroup_subsys *ss = css->ss;

	int ret = 0;



	lockdep_assert_held(&cgroup_mutex);
@@ -4342,9 +4340,9 @@ static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp) 
}



/* if the CSS is online, invoke ->css_offline() on it and mark it offline */

static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)

static void offline_css(struct cgroup_subsys_state *css)

{

	struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);

	struct cgroup_subsys *ss = css->ss;



	lockdep_assert_held(&cgroup_mutex);
@@ -4442,10 +4440,10 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 
			goto err_free_all;

		}



		init_cgroup_css(css, ss, cgrp);

		init_css(css, ss, cgrp);



		if (ss->use_id) {

			err = alloc_css_id(ss, parent, cgrp);

			err = alloc_css_id(css);

			if (err)

				goto err_free_all;

		}
@@ -4480,7 +4478,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 


	/* creation succeeded, notify subsystems */

	for_each_root_subsys(root, ss) {

		err = online_css(ss, cgrp);

		struct cgroup_subsys_state *css = cgroup_css(cgrp, ss->subsys_id);



		err = online_css(css);

		if (err)

			goto err_destroy;
@@ -4700,7 +4700,7 @@ static void cgroup_offline_fn(struct work_struct *work) 
	 * initate destruction.

	 */

	for_each_root_subsys(cgrp->root, ss)

		offline_css(ss, cgrp);

		offline_css(cgroup_css(cgrp, ss->subsys_id));



	/*

	 * Put the css refs from cgroup_destroy_locked().  Each css holds
@@ -4778,7 +4778,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) 
	css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss->subsys_id));

	/* We don't handle early failures gracefully */

	BUG_ON(IS_ERR(css));

	init_cgroup_css(css, ss, cgroup_dummy_top);

	init_css(css, ss, cgroup_dummy_top);



	/* Update the init_css_set to contain a subsys

	 * pointer to this state - since the subsystem is
@@ -4793,7 +4793,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) 
	 * need to invoke fork callbacks here. */

	BUG_ON(!list_empty(&init_task.tasks));



	BUG_ON(online_css(ss, cgroup_dummy_top));

	BUG_ON(online_css(cgroup_css(cgroup_dummy_top, ss->subsys_id)));



	mutex_unlock(&cgroup_mutex);
@@ -4866,8 +4866,8 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) 
	ss->root = &cgroup_dummy_root;



	/* our new subsystem will be attached to the dummy hierarchy. */

	init_cgroup_css(css, ss, cgroup_dummy_top);

	/* init_idr must be after init_cgroup_css because it sets css->id. */

	init_css(css, ss, cgroup_dummy_top);

	/* init_idr must be after init_css() because it sets css->id. */

	if (ss->use_id) {

		ret = cgroup_init_idr(ss, css);

		if (ret)
@@ -4897,7 +4897,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) 
	}

	write_unlock(&css_set_lock);



	ret = online_css(ss, cgroup_dummy_top);

	ret = online_css(cgroup_css(cgroup_dummy_top, ss->subsys_id));

	if (ret)

		goto err_unload;
@@ -4936,7 +4936,7 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) 


	mutex_lock(&cgroup_mutex);



	offline_css(ss, cgroup_dummy_top);

	offline_css(cgroup_css(cgroup_dummy_top, ss->subsys_id));



	if (ss->use_id)

		idr_destroy(&ss->idr);
@@ -5588,20 +5588,16 @@ static int __init_or_module cgroup_init_idr(struct cgroup_subsys *ss, 
	return 0;

}



static int alloc_css_id(struct cgroup_subsys *ss, struct cgroup *parent,

			struct cgroup *child)

static int alloc_css_id(struct cgroup_subsys_state *child_css)

{

	int subsys_id, i, depth = 0;

	struct cgroup_subsys_state *parent_css, *child_css;

	struct cgroup_subsys_state *parent_css = css_parent(child_css);

	struct css_id *child_id, *parent_id;

	int i, depth;



	subsys_id = ss->subsys_id;

	parent_css = cgroup_css(parent, subsys_id);

	child_css = cgroup_css(child, subsys_id);

	parent_id = rcu_dereference_protected(parent_css->id, true);

	depth = parent_id->depth + 1;



	child_id = get_new_cssid(ss, depth);

	child_id = get_new_cssid(child_css->ss, depth);

	if (IS_ERR(child_id))

		return PTR_ERR(child_id);