cgroup: use new hashtable implementation

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>

1 files changed, 39 insertions, 53 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 6643f7053454..54b39081ac04 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -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>
@@ -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
@@ -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,
@@ -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
@@ -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;
 
@@ -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 */
@@ -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);
 
@@ -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);
 
@@ -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);
@@ -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 ||
@@ -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);
 
@@ -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);
 
@@ -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);
 
@@ -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];
 
@@ -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)
@@ -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);