[PATCH v7 02/16] userns: use new hashtable implementation

Sasha Levin
2012-10-28T19:03:14Z

Switch to using the new hashtable implementation to store user structs.
This reduces the amount of generic unrelated code in kernel/user.c.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
kernel/user.c | 33 +++++++++++++--------------------
1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/kernel/user.c b/kernel/user.c
index 750acff..8cd922a 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -16,6 +16,7 @@
#include <linux/interrupt.h>
#include <linux/export.h>
#include <linux/user_namespace.h>
+#include <linux/hashtable.h>

/*
* userns count is 1 for root user, 1 for init_uts_ns,
@@ -60,13 +61,9 @@ EXPORT_SYMBOL_GPL(init_user_ns);
*/

#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
-#define UIDHASH_SZ (1 << UIDHASH_BITS)
-#define UIDHASH_MASK (UIDHASH_SZ - 1)
-#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
-#define uidhashentry(uid) (uidhash_table + __uidhashfn((__kuid_val(uid))))

static struct kmem_cache *uid_cachep;
-struct hlist_head uidhash_table[UIDHASH_SZ];
+static DEFINE_HASHTABLE(uidhash_table, UIDHASH_BITS);

/*
* The uidhash_lock is mostly taken from process context, but it is
@@ -92,22 +89,22 @@ struct user_struct root_user = {
/*
* These routines must be called with the uidhash spinlock held!
*/
-static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
+static void uid_hash_insert(struct user_struct *up)
{
- hlist_add_head(&up->uidhash_node, hashent);
+ hash_add(uidhash_table, &up->uidhash_node, __kuid_val(up->uid));
}

static void uid_hash_remove(struct user_struct *up)
{
- hlist_del_init(&up->uidhash_node);
+ hash_del(&up->uidhash_node);
}

-static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent)
+static struct user_struct *uid_hash_find(kuid_t uid)
{
struct user_struct *user;
struct hlist_node *h;

- hlist_for_each_entry(user, h, hashent, uidhash_node) {
+ hash_for_each_possible(uidhash_table, user, h, uidhash_node, __kuid_val(uid)) {
if (uid_eq(user->uid, uid)) {
atomic_inc(&user->__count);
return user;
@@ -143,7 +140,7 @@ struct user_struct *find_user(kuid_t uid)
unsigned long flags;

spin_lock_irqsave(&uidhash_lock, flags);
- ret = uid_hash_find(uid, uidhashentry(uid));
+ ret = uid_hash_find(uid);
spin_unlock_irqrestore(&uidhash_lock, flags);
return ret;
}
@@ -164,11 +161,10 @@ void free_uid(struct user_struct *up)

struct user_struct *alloc_uid(kuid_t uid)
{
- struct hlist_head *hashent = uidhashentry(uid);
struct user_struct *up, *new;

spin_lock_irq(&uidhash_lock);
- up = uid_hash_find(uid, hashent);
+ up = uid_hash_find(uid);
spin_unlock_irq(&uidhash_lock);

if (!up) {
@@ -184,13 +180,13 @@ struct user_struct *alloc_uid(kuid_t uid)
* on adding the same user already..
*/
spin_lock_irq(&uidhash_lock);
- up = uid_hash_find(uid, hashent);
+ up = uid_hash_find(uid);
if (up) {
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
} else {
- uid_hash_insert(new, hashent);
+ uid_hash_insert(new);
up = new;
}
spin_unlock_irq(&uidhash_lock);
@@ -204,17 +200,14 @@ out_unlock:

static int __init uid_cache_init(void)
{
- int n;
-
uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);

- for(n = 0; n < UIDHASH_SZ; ++n)
- INIT_HLIST_HEAD(uidhash_table + n);
+ hash_init(uidhash_table);

/* Insert the root user immediately (init already runs as root) */
spin_lock_irq(&uidhash_lock);
- uid_hash_insert(&root_user, uidhashentry(GLOBAL_ROOT_UID));
+ uid_hash_insert(&root_user);
spin_unlock_irq(&uidhash_lock);

return 0;
--
1.7.12.4