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Date: Wed, 24 Feb 2016 17:02:33 -0500
From: Tejun Heo <tj@...nel.org>
To: lizefan@...wei.com, hannes@...xchg.org
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
kernel-team@...com, Tejun Heo <tj@...nel.org>
Subject: [PATCH 01/16] cgroup: separate out interface file creation from css creation
Currently, interface files are created when a css is created depending
on whether @visible is set. This patch separates out the two into
separate steps to help code refactoring and eventually allow cgroups
which aren't visible through cgroup fs.
Move css_populate_dir() out of create_css() and drop @visible. While
at it, rename the function to css_create() for consistency.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
kernel/cgroup.c | 72 ++++++++++++++++++++++++++++++++++-----------------------
1 file changed, 43 insertions(+), 29 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ac5451e..3784f5a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -222,8 +222,8 @@ static struct cftype cgroup_legacy_base_files[];
static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
static void css_task_iter_advance(struct css_task_iter *it);
static int cgroup_destroy_locked(struct cgroup *cgrp);
-static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
- bool visible);
+static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
+ struct cgroup_subsys *ss);
static void css_release(struct percpu_ref *ref);
static void kill_css(struct cgroup_subsys_state *css);
static int cgroup_addrm_files(struct cgroup_subsys_state *css,
@@ -3081,14 +3081,26 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
*/
do_each_subsys_mask(ss, ssid, enable) {
cgroup_for_each_live_child(child, cgrp) {
- if (css_enable & (1 << ssid))
- ret = create_css(child, ss,
- cgrp->subtree_control & (1 << ssid));
- else
+ if (css_enable & (1 << ssid)) {
+ struct cgroup_subsys_state *css;
+
+ css = css_create(child, ss);
+ if (IS_ERR(css)) {
+ ret = PTR_ERR(css);
+ goto err_undo_css;
+ }
+
+ if (cgrp->subtree_control & (1 << ssid)) {
+ ret = css_populate_dir(css, NULL);
+ if (ret)
+ goto err_undo_css;
+ }
+ } else {
ret = css_populate_dir(cgroup_css(child, ss),
NULL);
- if (ret)
- goto err_undo_css;
+ if (ret)
+ goto err_undo_css;
+ }
}
} while_each_subsys_mask();
@@ -4716,7 +4728,9 @@ static void css_release_work_fn(struct work_struct *work)
* Those are supported by RCU protecting clearing of
* cgrp->kn->priv backpointer.
*/
- RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL);
+ if (cgrp->kn)
+ RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
+ NULL);
}
mutex_unlock(&cgroup_mutex);
@@ -4797,17 +4811,16 @@ static void offline_css(struct cgroup_subsys_state *css)
}
/**
- * create_css - create a cgroup_subsys_state
+ * css_create - create a cgroup_subsys_state
* @cgrp: the cgroup new css will be associated with
* @ss: the subsys of new css
- * @visible: whether to create control knobs for the new css or not
*
* 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 if
- * @visible. Returns 0 on success, -errno on failure.
+ * css is online and installed in @cgrp. This function doesn't create the
+ * interface files. Returns 0 on success, -errno on failure.
*/
-static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
- bool visible)
+static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
{
struct cgroup *parent = cgroup_parent(cgrp);
struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
@@ -4818,7 +4831,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
css = ss->css_alloc(parent_css);
if (IS_ERR(css))
- return PTR_ERR(css);
+ return css;
init_and_link_css(css, ss, cgrp);
@@ -4831,12 +4844,6 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
goto err_free_percpu_ref;
css->id = err;
- if (visible) {
- err = css_populate_dir(css, NULL);
- if (err)
- goto err_free_id;
- }
-
/* @css is ready to be brought online now, make it visible */
list_add_tail_rcu(&css->sibling, &parent_css->children);
cgroup_idr_replace(&ss->css_idr, css, css->id);
@@ -4854,18 +4861,16 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
ss->warned_broken_hierarchy = true;
}
- return 0;
+ return css;
err_list_del:
list_del_rcu(&css->sibling);
- css_clear_dir(css, NULL);
-err_free_id:
cgroup_idr_remove(&ss->css_idr, css->id);
err_free_percpu_ref:
percpu_ref_exit(&css->refcnt);
err_free_css:
call_rcu(&css->rcu_head, css_free_rcu_fn);
- return err;
+ return ERR_PTR(err);
}
static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
@@ -4962,10 +4967,19 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
/* let's create and online css's */
do_each_subsys_mask(ss, ssid, parent->subtree_ss_mask) {
- ret = create_css(cgrp, ss,
- parent->subtree_control & (1 << ssid));
- if (ret)
+ struct cgroup_subsys_state *css;
+
+ css = css_create(cgrp, ss);
+ if (IS_ERR(css)) {
+ ret = PTR_ERR(css);
goto out_destroy;
+ }
+
+ if (parent->subtree_control & (1 << ssid)) {
+ ret = css_populate_dir(css, NULL);
+ if (ret)
+ goto out_destroy;
+ }
} while_each_subsys_mask();
/*
--
2.5.0
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