Convert uid hash to hlist

Surprisingly, but (spotted by Alexey Dobriyan) the uid hash still uses
list_heads, thus occupying twice as much place as it could.  Convert it to
hlist_heads.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 11 insertions, 10 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f4e324ed2e44..6239bc2c2baa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -593,7 +593,7 @@ struct user_struct {
 #endif
 
         /* Hash table maintenance information */
-        struct list_head uidhash_list;
+        struct hlist_node uidhash_node;
         uid_t uid;
 };
 
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 1101b0ce878f..b5f41d4c2eec 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -11,7 +11,7 @@
 
 struct user_namespace {
         struct kref             kref;
-        struct list_head        uidhash_table[UIDHASH_SZ];
+        struct hlist_head       uidhash_table[UIDHASH_SZ];
         struct user_struct      *root_user;
 };
 
diff --git a/kernel/user.c b/kernel/user.c
index e080ba863ae3..add57c7e4c07 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -55,21 +55,22 @@ struct user_struct root_user = {
 /*
  * These routines must be called with the uidhash spinlock held!
  */
-static inline void uid_hash_insert(struct user_struct *up, struct list_head *hashent)
+static inline void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
 {
-        list_add(&up->uidhash_list, hashent);
+        hlist_add_head(&up->uidhash_node, hashent);
 }
 
 static inline void uid_hash_remove(struct user_struct *up)
 {
-        list_del(&up->uidhash_list);
+        hlist_del(&up->uidhash_node);
 }
 
-static inline struct user_struct *uid_hash_find(uid_t uid, struct list_head *hashent)
+static inline struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
 {
         struct user_struct *user;
+        struct hlist_node *h;
 
-        list_for_each_entry(user, hashent, uidhash_list) {
+        hlist_for_each_entry(user, h, hashent, uidhash_node) {
                 if(user->uid == uid) {
                         atomic_inc(&user->__count);
                         return user;
@@ -118,7 +119,7 @@ void free_uid(struct user_struct *up)
 
 struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
 {
-        struct list_head *hashent = uidhashentry(ns, uid);
+        struct hlist_head *hashent = uidhashentry(ns, uid);
         struct user_struct *up;
 
         spin_lock_irq(&uidhash_lock);
@@ -207,7 +208,7 @@ static int __init uid_cache_init(void)
                         0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
 
         for(n = 0; n < UIDHASH_SZ; ++n)
-                INIT_LIST_HEAD(init_user_ns.uidhash_table + n);
+                INIT_HLIST_HEAD(init_user_ns.uidhash_table + n);
 
         /* Insert the root user immediately (init already runs as root) */
         spin_lock_irq(&uidhash_lock);
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 85af9422ea6e..e7ba1bf8457c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -39,7 +39,7 @@ static struct user_namespace *clone_user_ns(struct user_namespace *old_ns)
         kref_init(&ns->kref);
 
         for (n = 0; n < UIDHASH_SZ; ++n)
-                INIT_LIST_HEAD(ns->uidhash_table + n);
+                INIT_HLIST_HEAD(ns->uidhash_table + n);
 
         /* Insert new root user.  */
         ns->root_user = alloc_uid(ns, 0);