Commit b85d2040 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: remove for_each_root_subsys() 



After the previous patch which introduced for_each_css(),
for_each_root_subsys() only has two users left.  This patch replaces
it with for_each_subsys() + explicit subsys_mask testing and remove
for_each_root_subsys() along with cgroupfs_root->subsys_list handling.

This patch doesn't introduce any behavior changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 1c6727af

include/linux/cgroup.h

+1 −8
Original line number Diff line number Diff line
@@ -319,9 +319,6 @@ struct cgroupfs_root { 
	/* Unique id for this hierarchy. */

	int hierarchy_id;



	/* A list running through the attached subsystems */

	struct list_head subsys_list;



	/* The root cgroup for this hierarchy */

	struct cgroup top_cgroup;
@@ -617,12 +614,8 @@ struct cgroup_subsys { 
#define MAX_CGROUP_TYPE_NAMELEN 32

	const char *name;



	/*

	 * Link to parent, and list entry in parent's children.

	 * Protected by cgroup_lock()

	 */

	/* link to parent, protected by cgroup_lock() */

	struct cgroupfs_root *root;

	struct list_head sibling;



	/* list of cftype_sets */

	struct list_head cftsets;

kernel/cgroup.c

+15 −22
Original line number Diff line number Diff line
@@ -283,10 +283,6 @@ static int notify_on_release(const struct cgroup *cgrp) 
	for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT &&		\

	     (((ss) = cgroup_subsys[i]) || true); (i)++)



/* iterate each subsystem attached to a hierarchy */

#define for_each_root_subsys(root, ss)					\

	list_for_each_entry((ss), &(root)->subsys_list, sibling)



/* iterate across the active hierarchies */

#define for_each_active_root(root)					\

	list_for_each_entry((root), &cgroup_roots, root_list)
@@ -1033,7 +1029,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, 
					   cgroup_css(cgroup_dummy_top, ss));

			cgroup_css(cgrp, ss)->cgroup = cgrp;



			list_move(&ss->sibling, &root->subsys_list);

			ss->root = root;

			if (ss->bind)

				ss->bind(cgroup_css(cgrp, ss));
@@ -1052,7 +1047,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, 
			RCU_INIT_POINTER(cgrp->subsys[i], NULL);



			cgroup_subsys[i]->root = &cgroup_dummy_root;

			list_move(&ss->sibling, &cgroup_dummy_root.subsys_list);



			/* subsystem is now free - drop reference on module */

			module_put(ss->module);
@@ -1079,9 +1073,11 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) 
{

	struct cgroupfs_root *root = dentry->d_sb->s_fs_info;

	struct cgroup_subsys *ss;

	int ssid;



	mutex_lock(&cgroup_root_mutex);

	for_each_root_subsys(root, ss)

	for_each_subsys(ss, ssid)

		if (root->subsys_mask & (1 << ssid))

			seq_printf(seq, ",%s", ss->name);

	if (root->flags & CGRP_ROOT_SANE_BEHAVIOR)

		seq_puts(seq, ",sane_behavior");
@@ -1352,7 +1348,6 @@ static void init_cgroup_root(struct cgroupfs_root *root) 
{

	struct cgroup *cgrp = &root->top_cgroup;



	INIT_LIST_HEAD(&root->subsys_list);

	INIT_LIST_HEAD(&root->root_list);

	root->number_of_cgroups = 1;

	cgrp->root = root;
@@ -4151,7 +4146,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 
	struct cgroup *cgrp;

	struct cgroup_name *name;

	struct cgroupfs_root *root = parent->root;

	int err = 0;

	int ssid, err = 0;

	struct cgroup_subsys *ss;

	struct super_block *sb = root->sb;
@@ -4237,11 +4232,13 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, 
		goto err_destroy;



	/* let's create and online css's */

	for_each_root_subsys(root, ss) {

	for_each_subsys(ss, ssid) {

		if (root->subsys_mask & (1 << ssid)) {

			err = create_css(cgrp, ss);

			if (err)

				goto err_destroy;

		}

	}



	mutex_unlock(&cgroup_mutex);

	mutex_unlock(&cgrp->dentry->d_inode->i_mutex);
@@ -4536,7 +4533,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) 
	cgroup_init_cftsets(ss);



	/* Create the top cgroup state for this subsystem */

	list_add(&ss->sibling, &cgroup_dummy_root.subsys_list);

	ss->root = &cgroup_dummy_root;

	css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss));

	/* We don't handle early failures gracefully */
@@ -4626,7 +4622,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) 
		return PTR_ERR(css);

	}



	list_add(&ss->sibling, &cgroup_dummy_root.subsys_list);

	ss->root = &cgroup_dummy_root;



	/* our new subsystem will be attached to the dummy hierarchy. */
@@ -4702,9 +4697,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) 
	/* deassign the subsys_id */

	cgroup_subsys[ss->subsys_id] = NULL;



	/* remove subsystem from the dummy root's list of subsystems */

	list_del_init(&ss->sibling);



	/*

	 * disentangle the css from all css_sets attached to the dummy

	 * top. as in loading, we need to pay our respects to the hashtable
@@ -4901,10 +4893,11 @@ int proc_cgroup_show(struct seq_file *m, void *v) 
	for_each_active_root(root) {

		struct cgroup_subsys *ss;

		struct cgroup *cgrp;

		int count = 0;

		int ssid, count = 0;



		seq_printf(m, "%d:", root->hierarchy_id);

		for_each_root_subsys(root, ss)

		for_each_subsys(ss, ssid)

			if (root->subsys_mask & (1 << ssid))

				seq_printf(m, "%s%s", count++ ? "," : "", ss->name);

		if (strlen(root->name))

			seq_printf(m, "%sname=%s", count ? "," : "",

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