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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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2013-12-06 15:11:57 -05:00
parent 1c6727af4b
commit b85d20404c
2 changed files with 16 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/cgroup.h
View File

@ -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;

37
kernel/cgroup.c
View File

@ -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);
@ -1079,10 +1073,12 @@ 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)
seq_printf(seq, ",%s", ss->name);
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");
if (root->flags & CGRP_ROOT_NOPREFIX)
@ -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;
@ -4237,10 +4232,12 @@ 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) {
err = create_css(cgrp, ss);
if (err)
goto err_destroy;
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);
@ -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
@ -4901,11 +4893,12 @@ 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)
seq_printf(m, "%s%s", count++ ? "," : "", ss->name);
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 ? "," : "",
root->name);