[Devel] [PATCH 1/2] Convert uid hash to hlist

[Pavel Emelyanov]

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 at openvz.org>
Signed-off-by: Alexey Dobriyan <adobriyan at openvz.org>
Cc: Serge Hallyn <serue at us.ibm.com>

---

 include/linux/sched.h          |    2 +-
 include/linux/user_namespace.h |    2 +-
 kernel/user.c                  |   15 ++++++++-------
 kernel/user_namespace.c        |    2 +-
 4 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f6cf87e..a2afa88 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -535,7 +535,7 @@ 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 1101b0c..b5f41d4 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 e080ba8..add57c7 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 df1d2cf..7af90fc 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -39,7 +39,7 @@ static struct user_namespace *clone_user
 	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);