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cgroup: factor out cgroup_subsys_state creation into create_css()

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Now that all opertations to create a css (cgroup_subsys_state) are
collected into a single loop in cgroup_create(), it's easy to factor
it out into its own function.  Factor out css creation into
create_css().  This makes the code easier to follow and will enable
decoupling css creation from cgroup creation which is necessary for
the planned unified hierarchy.

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 15:11:56 -05:00
parent 9d403e9923
commit c81c925ad9
1 changed files with 57 additions and 38 deletions
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95
kernel/cgroup.c
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@ -4073,6 +4073,62 @@ static void offline_css(struct cgroup_subsys_state *css)
RCU_INIT_POINTER(css->cgroup->subsys[ss->subsys_id], css);
}
/**
* create_css - create a cgroup_subsys_state
* @cgrp: the cgroup new css will be associated with
* @ss: the subsys of new css
*
* Create a new css associated with @cgrp - @ss pair. On success, the new
* css is online and installed in @cgrp with all interface files created.
* Returns 0 on success, -errno on failure.
*/
static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
{
struct cgroup *parent = cgrp->parent;
struct cgroup_subsys_state *css;
int err;
lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
lockdep_assert_held(&cgroup_mutex);
css = ss->css_alloc(cgroup_css(parent, ss));
if (IS_ERR(css))
return PTR_ERR(css);
err = percpu_ref_init(&css->refcnt, css_release);
if (err)
goto err_free;
init_css(css, ss, cgrp);
err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);
if (err)
goto err_free;
err = online_css(css);
if (err)
goto err_free;
dget(cgrp->dentry);
css_get(css->parent);
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
parent->parent) {
pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
current->comm, current->pid, ss->name);
if (!strcmp(ss->name, "memory"))
pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
ss->warned_broken_hierarchy = true;
}
return 0;
err_free:
percpu_ref_cancel_init(&css->refcnt);
ss->css_free(css);
return err;
}
/*
* cgroup_create - create a cgroup
* @parent: cgroup that will be parent of the new cgroup
@ -4084,7 +4140,6 @@ static void offline_css(struct cgroup_subsys_state *css)
static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
umode_t mode)
{
struct cgroup_subsys_state *css = NULL;
struct cgroup *cgrp;
struct cgroup_name *name;
struct cgroupfs_root *root = parent->root;
@ -4175,41 +4230,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
/* let's create and online css's */
for_each_root_subsys(root, ss) {
css = ss->css_alloc(cgroup_css(parent, ss));
if (IS_ERR(css)) {
err = PTR_ERR(css);
css = NULL;
goto err_destroy;
}
err = percpu_ref_init(&css->refcnt, css_release);
err = create_css(cgrp, ss);
if (err)
goto err_destroy;
init_css(css, ss, cgrp);
err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);
if (err)
goto err_destroy;
err = online_css(css);
if (err)
goto err_destroy;
dget(dentry);
css_get(css->parent);
/* mark it consumed for error path */
css = NULL;
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
parent->parent) {
pr_warning("cgroup: %s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
current->comm, current->pid, ss->name);
if (!strcmp(ss->name, "memory"))
pr_warning("cgroup: \"memory\" requires setting use_hierarchy to 1 on the root.\n");
ss->warned_broken_hierarchy = true;
}
}
mutex_unlock(&cgroup_mutex);
@ -4230,10 +4253,6 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
return err;
err_destroy:
if (css) {
percpu_ref_cancel_init(&css->refcnt);
css->ss->css_free(css);
}
cgroup_destroy_locked(cgrp);
mutex_unlock(&cgroup_mutex);
mutex_unlock(&dentry->d_inode->i_mutex);