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Date: Tue, 31 Jul 2012 20:05:18 +0200
From: Sasha Levin <levinsasha928@...il.com>
To: torvalds@...ux-foundation.org
Cc: tj@...nel.org, akpm@...ux-foundation.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
paul.gortmaker@...driver.com, Sasha Levin <levinsasha928@...il.com>
Subject: [RFC 2/4] user_ns: use new hashtable implementation
Switch user_ns to use the new hashtable implementation. This reduces the amount of
generic unrelated code in user_ns.
Signed-off-by: Sasha Levin <levinsasha928@...il.com>
---
include/linux/user_namespace.h | 11 +++++---
kernel/user.c | 54 +++++++--------------------------------
kernel/user_namespace.c | 4 +--
3 files changed, 18 insertions(+), 51 deletions(-)
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index faf4679..cbbe342 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -5,13 +5,16 @@
#include <linux/nsproxy.h>
#include <linux/sched.h>
#include <linux/err.h>
+#include <linux/hashtable.h>
-#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
-#define UIDHASH_SZ (1 << UIDHASH_BITS)
-
+#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
+#define UIDHASH_CMP(obj, key) ((obj)->uid == (key))
+#define UIDHASH_ENTRY(ns, key) (HASH_GET((ns)->uidhash_table, key, \
+ struct user_struct, uidhash_node, \
+ UIDHASH_CMP))
struct user_namespace {
struct kref kref;
- struct hlist_head uidhash_table[UIDHASH_SZ];
+ DEFINE_HASHTABLE(uidhash_table, UIDHASH_BITS);
struct user_struct *creator;
struct work_struct destroyer;
};
diff --git a/kernel/user.c b/kernel/user.c
index 71dd236..3b8367c 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -34,10 +34,6 @@ EXPORT_SYMBOL_GPL(init_user_ns);
* when changing user ID's (ie setuid() and friends).
*/
-#define UIDHASH_MASK (UIDHASH_SZ - 1)
-#define __uidhashfn(uid) (((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
-#define uidhashentry(ns, uid) ((ns)->uidhash_table + __uidhashfn((uid)))
-
static struct kmem_cache *uid_cachep;
/*
@@ -61,35 +57,6 @@ struct user_struct root_user = {
.user_ns = &init_user_ns,
};
-/*
- * These routines must be called with the uidhash spinlock held!
- */
-static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
-{
- hlist_add_head(&up->uidhash_node, hashent);
-}
-
-static void uid_hash_remove(struct user_struct *up)
-{
- hlist_del_init(&up->uidhash_node);
- put_user_ns(up->user_ns);
-}
-
-static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
-{
- struct user_struct *user;
- struct hlist_node *h;
-
- hlist_for_each_entry(user, h, hashent, uidhash_node) {
- if (user->uid == uid) {
- atomic_inc(&user->__count);
- return user;
- }
- }
-
- return NULL;
-}
-
/* IRQs are disabled and uidhash_lock is held upon function entry.
* IRQ state (as stored in flags) is restored and uidhash_lock released
* upon function exit.
@@ -97,7 +64,8 @@ static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
static void free_user(struct user_struct *up, unsigned long flags)
__releases(&uidhash_lock)
{
- uid_hash_remove(up);
+ HASH_DEL(up, uidhash_node);
+ put_user_ns(up->user_ns);
spin_unlock_irqrestore(&uidhash_lock, flags);
key_put(up->uid_keyring);
key_put(up->session_keyring);
@@ -117,7 +85,9 @@ struct user_struct *find_user(uid_t uid)
struct user_namespace *ns = current_user_ns();
spin_lock_irqsave(&uidhash_lock, flags);
- ret = uid_hash_find(uid, uidhashentry(ns, uid));
+ ret = UIDHASH_ENTRY(ns, uid);
+ if (ret)
+ atomic_inc(&ret->__count);
spin_unlock_irqrestore(&uidhash_lock, flags);
return ret;
}
@@ -138,11 +108,10 @@ void free_uid(struct user_struct *up)
struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
{
- struct hlist_head *hashent = uidhashentry(ns, uid);
struct user_struct *up, *new;
spin_lock_irq(&uidhash_lock);
- up = uid_hash_find(uid, hashent);
+ up = UIDHASH_ENTRY(ns, uid);
spin_unlock_irq(&uidhash_lock);
if (!up) {
@@ -160,14 +129,14 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
* on adding the same user already..
*/
spin_lock_irq(&uidhash_lock);
- up = uid_hash_find(uid, hashent);
+ up = UIDHASH_ENTRY(ns, uid);
if (up) {
put_user_ns(ns);
key_put(new->uid_keyring);
key_put(new->session_keyring);
kmem_cache_free(uid_cachep, new);
} else {
- uid_hash_insert(new, hashent);
+ HASH_ADD(ns->uidhash_table, &new->uidhash_node, uid);
up = new;
}
spin_unlock_irq(&uidhash_lock);
@@ -181,17 +150,14 @@ 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(init_user_ns.uidhash_table + n);
+ HASH_INIT(init_user_ns.uidhash_table);
/* Insert the root user immediately (init already runs as root) */
spin_lock_irq(&uidhash_lock);
- uid_hash_insert(&root_user, uidhashentry(&init_user_ns, 0));
+ HASH_ADD(init_user_ns.uidhash_table, &root_user.uidhash_node, 0);
spin_unlock_irq(&uidhash_lock);
return 0;
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 3b906e9..914c8c5 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -26,7 +26,6 @@ int create_user_ns(struct cred *new)
{
struct user_namespace *ns;
struct user_struct *root_user;
- int n;
ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);
if (!ns)
@@ -34,8 +33,7 @@ int create_user_ns(struct cred *new)
kref_init(&ns->kref);
- for (n = 0; n < UIDHASH_SZ; ++n)
- INIT_HLIST_HEAD(ns->uidhash_table + n);
+ HASH_INIT(ns->uidhash_table);
/* Alloc new root user. */
root_user = alloc_uid(ns, 0);
--
1.7.8.6
--
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