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Message-Id: <1377723829-22814-10-git-send-email-tj@kernel.org>
Date: Wed, 28 Aug 2013 17:03:49 -0400
From: Tejun Heo <tj@...nel.org>
To: lizefan@...wei.com
Cc: containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>
Subject: [PATCH 9/9] 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@...nel.org>
---
include/linux/cgroup.h | 10 ++--------
kernel/cgroup.c | 37 +++++++++++++++----------------------
2 files changed, 17 insertions(+), 30 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 3561d30..965548f 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -320,9 +320,6 @@ 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;
@@ -636,12 +633,9 @@ 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;
+
/* used when use_id == true */
struct idr idr;
spinlock_t id_lock;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 88684ce..66da7f8 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -331,10 +331,6 @@ 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)
@@ -1096,7 +1092,6 @@ 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));
@@ -1115,7 +1110,6 @@ 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);
@@ -1142,10 +1136,12 @@ 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)
@@ -1417,7 +1413,6 @@ 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;
@@ -4469,7 +4464,7 @@ 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;
@@ -4555,10 +4550,12 @@ 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);
@@ -4850,7 +4847,6 @@ 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 */
@@ -4940,7 +4936,6 @@ 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. */
@@ -5025,9 +5020,6 @@ 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
@@ -5202,11 +5194,12 @@ 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);
--
1.8.3.1
--
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