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cgroup: reorganize css init / exit paths

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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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2013-08-13 11:01:55 -04:00
parent 73e80ed800
commit 623f926b05
1 changed files with 23 additions and 27 deletions
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50
kernel/cgroup.c
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@ -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)
{
@ -4308,9 +4307,8 @@ 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,
struct cgroup *cgrp)
static void init_css(struct cgroup_subsys_state *css, struct cgroup_subsys *ss,
struct cgroup *cgrp)
{
css->cgroup = cgrp;
css->ss = ss;
@ -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);