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cgroup: use new hashtable implementation
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Switch cgroup to use the new hashtable implementation. No functional changes.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Li Zefan authored and Tejun Heo committed Jan 10, 2013
1 parent 799105d commit 0ac801f
Showing 1 changed file with 39 additions and 53 deletions.
92 changes: 39 additions & 53 deletions kernel/cgroup.c
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@
#include <linux/module.h>
#include <linux/delayacct.h>
#include <linux/cgroupstats.h>
#include <linux/hash.h>
#include <linux/hashtable.h>
#include <linux/namei.h>
#include <linux/pid_namespace.h>
#include <linux/idr.h>
Expand Down Expand Up @@ -376,22 +376,18 @@ static int css_set_count;
* account cgroups in empty hierarchies.
*/
#define CSS_SET_HASH_BITS 7
#define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS)
static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE];
static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);

static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[])
static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
{
int i;
int index;
unsigned long tmp = 0UL;
unsigned long key = 0UL;

for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
tmp += (unsigned long)css[i];
tmp = (tmp >> 16) ^ tmp;
key += (unsigned long)css[i];
key = (key >> 16) ^ key;

index = hash_long(tmp, CSS_SET_HASH_BITS);

return &css_set_table[index];
return key;
}

/* We don't maintain the lists running through each css_set to its
Expand All @@ -418,7 +414,7 @@ static void __put_css_set(struct css_set *cg, int taskexit)
}

/* This css_set is dead. unlink it and release cgroup refcounts */
hlist_del(&cg->hlist);
hash_del(&cg->hlist);
css_set_count--;

list_for_each_entry_safe(link, saved_link, &cg->cg_links,
Expand Down Expand Up @@ -550,9 +546,9 @@ static struct css_set *find_existing_css_set(
{
int i;
struct cgroupfs_root *root = cgrp->root;
struct hlist_head *hhead;
struct hlist_node *node;
struct css_set *cg;
unsigned long key;

/*
* Build the set of subsystem state objects that we want to see in the
Expand All @@ -572,8 +568,8 @@ static struct css_set *find_existing_css_set(
}
}

hhead = css_set_hash(template);
hlist_for_each_entry(cg, node, hhead, hlist) {
key = css_set_hash(template);
hash_for_each_possible(css_set_table, cg, node, hlist, key) {
if (!compare_css_sets(cg, oldcg, cgrp, template))
continue;

Expand Down Expand Up @@ -657,8 +653,8 @@ static struct css_set *find_css_set(

struct list_head tmp_cg_links;

struct hlist_head *hhead;
struct cg_cgroup_link *link;
unsigned long key;

/* First see if we already have a cgroup group that matches
* the desired set */
Expand Down Expand Up @@ -704,8 +700,8 @@ static struct css_set *find_css_set(
css_set_count++;

/* Add this cgroup group to the hash table */
hhead = css_set_hash(res->subsys);
hlist_add_head(&res->hlist, hhead);
key = css_set_hash(res->subsys);
hash_add(css_set_table, &res->hlist, key);

write_unlock(&css_set_lock);

Expand Down Expand Up @@ -1597,6 +1593,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
struct cgroupfs_root *existing_root;
const struct cred *cred;
int i;
struct hlist_node *node;
struct css_set *cg;

BUG_ON(sb->s_root != NULL);

Expand Down Expand Up @@ -1650,14 +1648,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
/* Link the top cgroup in this hierarchy into all
* the css_set objects */
write_lock(&css_set_lock);
for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
struct hlist_head *hhead = &css_set_table[i];
struct hlist_node *node;
struct css_set *cg;

hlist_for_each_entry(cg, node, hhead, hlist)
link_css_set(&tmp_cg_links, cg, root_cgrp);
}
hash_for_each(css_set_table, i, node, cg, hlist)
link_css_set(&tmp_cg_links, cg, root_cgrp);
write_unlock(&css_set_lock);

free_cg_links(&tmp_cg_links);
Expand Down Expand Up @@ -4464,6 +4456,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
int i, ret;
struct hlist_node *node, *tmp;
struct css_set *cg;
unsigned long key;

/* check name and function validity */
if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
Expand Down Expand Up @@ -4529,23 +4524,17 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
* this is all done under the css_set_lock.
*/
write_lock(&css_set_lock);
for (i = 0; i < CSS_SET_TABLE_SIZE; i++) {
struct css_set *cg;
struct hlist_node *node, *tmp;
struct hlist_head *bucket = &css_set_table[i], *new_bucket;

hlist_for_each_entry_safe(cg, node, tmp, bucket, hlist) {
/* skip entries that we already rehashed */
if (cg->subsys[ss->subsys_id])
continue;
/* remove existing entry */
hlist_del(&cg->hlist);
/* set new value */
cg->subsys[ss->subsys_id] = css;
/* recompute hash and restore entry */
new_bucket = css_set_hash(cg->subsys);
hlist_add_head(&cg->hlist, new_bucket);
}
hash_for_each_safe(css_set_table, i, node, tmp, cg, hlist) {
/* skip entries that we already rehashed */
if (cg->subsys[ss->subsys_id])
continue;
/* remove existing entry */
hash_del(&cg->hlist);
/* set new value */
cg->subsys[ss->subsys_id] = css;
/* recompute hash and restore entry */
key = css_set_hash(cg->subsys);
hash_add(css_set_table, node, key);
}
write_unlock(&css_set_lock);

Expand Down Expand Up @@ -4577,7 +4566,6 @@ EXPORT_SYMBOL_GPL(cgroup_load_subsys);
void cgroup_unload_subsys(struct cgroup_subsys *ss)
{
struct cg_cgroup_link *link;
struct hlist_head *hhead;

BUG_ON(ss->module == NULL);

Expand Down Expand Up @@ -4611,11 +4599,12 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
write_lock(&css_set_lock);
list_for_each_entry(link, &dummytop->css_sets, cgrp_link_list) {
struct css_set *cg = link->cg;
unsigned long key;

hlist_del(&cg->hlist);
hash_del(&cg->hlist);
cg->subsys[ss->subsys_id] = NULL;
hhead = css_set_hash(cg->subsys);
hlist_add_head(&cg->hlist, hhead);
key = css_set_hash(cg->subsys);
hash_add(css_set_table, &cg->hlist, key);
}
write_unlock(&css_set_lock);

Expand Down Expand Up @@ -4657,9 +4646,6 @@ int __init cgroup_init_early(void)
list_add(&init_css_set_link.cg_link_list,
&init_css_set.cg_links);

for (i = 0; i < CSS_SET_TABLE_SIZE; i++)
INIT_HLIST_HEAD(&css_set_table[i]);

for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];

Expand Down Expand Up @@ -4693,7 +4679,7 @@ int __init cgroup_init(void)
{
int err;
int i;
struct hlist_head *hhead;
unsigned long key;

err = bdi_init(&cgroup_backing_dev_info);
if (err)
Expand All @@ -4712,8 +4698,8 @@ int __init cgroup_init(void)
}

/* Add init_css_set to the hash table */
hhead = css_set_hash(init_css_set.subsys);
hlist_add_head(&init_css_set.hlist, hhead);
key = css_set_hash(init_css_set.subsys);
hash_add(css_set_table, &init_css_set.hlist, key);
BUG_ON(!init_root_id(&rootnode));

cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
Expand Down

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