3 files changed, 37 insertions, 14 deletions

diff --git a/kernel/user.c b/kernel/user.c
index e7d11cef699..9ca2848fc35 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -55,25 +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_init(&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 list_head *up;
-
-	list_for_each(up, hashent) {
-		struct user_struct *user;
-
-		user = list_entry(up, struct user_struct, uidhash_list);
+	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;
@@ -122,7 +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);
@@ -202,6 +199,30 @@ void switch_uid(struct user_struct *new_user)
 	suid_keys(current);
 }
 
+void release_uids(struct user_namespace *ns)
+{
+	int i;
+	unsigned long flags;
+	struct hlist_head *head;
+	struct hlist_node *nd;
+
+	spin_lock_irqsave(&uidhash_lock, flags);
+	/*
+	 * collapse the chains so that the user_struct-s will
+	 * be still alive, but not in hashes. subsequent free_uid()
+	 * will free them.
+	 */
+	for (i = 0; i < UIDHASH_SZ; i++) {
+		head = ns->uidhash_table + i;
+		while (!hlist_empty(head)) {
+			nd = head->first;
+			hlist_del_init(nd);
+		}
+	}
+	spin_unlock_irqrestore(&uidhash_lock, flags);
+
+	free_uid(ns->root_user);
+}
 
 static int __init uid_cache_init(void)
 {
@@ -211,7 +232,7 @@ 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 85af9422ea6..7af90fc4f0f 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);
@@ -81,7 +81,7 @@ void free_user_ns(struct kref *kref)
 	struct user_namespace *ns;
 
 	ns = container_of(kref, struct user_namespace, kref);
-	free_uid(ns->root_user);
+	release_uids(ns);
 	kfree(ns);
 }
 
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 9d8180a0f0d..816d7b24fa0 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -28,7 +28,9 @@ static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
 	if (!ns)
 		return ERR_PTR(-ENOMEM);
 
+	down_read(&uts_sem);
 	memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+	up_read(&uts_sem);
 	kref_init(&ns->kref);
 	return ns;
 }