2.6.24-rc8

 kernel

diff --git a/kernel/user.c b/kernel/user.c
index 9ca2848..8320a87 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -44,34 +44,36 @@ struct user_struct root_user = {
    .processes   = ATOMIC_INIT(1),
    .files      = ATOMIC_INIT(0),
    .sigpending   = ATOMIC_INIT(0),
-   .mq_bytes   = 0,
    .locked_shm     = 0,
 #ifdef CONFIG_KEYS
    .uid_keyring   = &root_user_keyring,
    .session_keyring = &root_session_keyring,
 #endif
+#ifdef CONFIG_FAIR_USER_SCHED
+   .tg      = &init_task_group,
+#endif
 };
 
 /*
  * These routines must be called with the uidhash spinlock held!
  */
-static inline void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
+static void uid_hash_insert(struct user_struct *up, struct hlist_head *hashent)
 {
    hlist_add_head(&up->uidhash_node, hashent);
 }
 
-static inline void uid_hash_remove(struct user_struct *up)
+static void uid_hash_remove(struct user_struct *up)
 {
    hlist_del_init(&up->uidhash_node);
 }
 
-static inline struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
+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) {
+      if (user->uid == uid) {
          atomic_inc(&user->__count);
          return user;
       }
@@ -80,6 +82,211 @@ static inline struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *ha
    return NULL;
 }
 
+#ifdef CONFIG_FAIR_USER_SCHED
+
+static void sched_destroy_user(struct user_struct *up)
+{
+   sched_destroy_group(up->tg);
+}
+
+static int sched_create_user(struct user_struct *up)
+{
+   int rc = 0;
+
+   up->tg = sched_create_group();
+   if (IS_ERR(up->tg))
+      rc = -ENOMEM;
+
+   return rc;
+}
+
+static void sched_switch_user(struct task_struct *p)
+{
+   sched_move_task(p);
+}
+
+#else   /* CONFIG_FAIR_USER_SCHED */
+
+static void sched_destroy_user(struct user_struct *up) { }
+static int sched_create_user(struct user_struct *up) { return 0; }
+static void sched_switch_user(struct task_struct *p) { }
+
+#endif   /* CONFIG_FAIR_USER_SCHED */
+
+#if defined(CONFIG_FAIR_USER_SCHED) && defined(CONFIG_SYSFS)
+
+static struct kobject uids_kobject; /* represents /sys/kernel/uids directory */
+static DEFINE_MUTEX(uids_mutex);
+
+static inline void uids_mutex_lock(void)
+{
+   mutex_lock(&uids_mutex);
+}
+
+static inline void uids_mutex_unlock(void)
+{
+   mutex_unlock(&uids_mutex);
+}
+
+/* return cpu shares held by the user */
+static ssize_t cpu_shares_show(struct kset *kset, char *buffer)
+{
+   struct user_struct *up = container_of(kset, struct user_struct, kset);
+
+   return sprintf(buffer, "%lu\n", sched_group_shares(up->tg));
+}
+
+/* modify cpu shares held by the user */
+static ssize_t cpu_shares_store(struct kset *kset, const char *buffer,
+            size_t size)
+{
+   struct user_struct *up = container_of(kset, struct user_struct, kset);
+   unsigned long shares;
+   int rc;
+
+   sscanf(buffer, "%lu", &shares);
+
+   rc = sched_group_set_shares(up->tg, shares);
+
+   return (rc ? rc : size);
+}
+
+static void user_attr_init(struct subsys_attribute *sa, char *name, int mode)
+{
+   sa->attr.name = name;
+   sa->attr.mode = mode;
+   sa->show = cpu_shares_show;
+   sa->store = cpu_shares_store;
+}
+
+/* Create "/sys/kernel/uids/<uid>" directory and
+ *  "/sys/kernel/uids/<uid>/cpu_share" file for this user.
+ */
+static int user_kobject_create(struct user_struct *up)
+{
+   struct kset *kset = &up->kset;
+   struct kobject *kobj = &kset->kobj;
+   int error;
+
+   memset(kset, 0, sizeof(struct kset));
+   kobj->parent = &uids_kobject;   /* create under /sys/kernel/uids dir */
+   kobject_set_name(kobj, "%d", up->uid);
+   kset_init(kset);
+   user_attr_init(&up->user_attr, "cpu_share", 0644);
+
+   error = kobject_add(kobj);
+   if (error)
+      goto done;
+
+   error = sysfs_create_file(kobj, &up->user_attr.attr);
+   if (error)
+      kobject_del(kobj);
+
+   kobject_uevent(kobj, KOBJ_ADD);
+
+done:
+   return error;
+}
+
+/* create these in sysfs filesystem:
+ *    "/sys/kernel/uids" directory
+ *    "/sys/kernel/uids/0" directory (for root user)
+ *    "/sys/kernel/uids/0/cpu_share" file (for root user)
+ */
+int __init uids_kobject_init(void)
+{
+   int error;
+
+   /* create under /sys/kernel dir */
+   uids_kobject.parent = &kernel_subsys.kobj;
+   uids_kobject.kset = &kernel_subsys;
+   kobject_set_name(&uids_kobject, "uids");
+   kobject_init(&uids_kobject);
+
+   error = kobject_add(&uids_kobject);
+   if (!error)
+      error = user_kobject_create(&root_user);
+
+   return error;
+}
+
+/* work function to remove sysfs directory for a user and free up
+ * corresponding structures.
+ */
+static void remove_user_sysfs_dir(struct work_struct *w)
+{
+   struct user_struct *up = container_of(w, struct user_struct, work);
+   struct kobject *kobj = &up->kset.kobj;
+   unsigned long flags;
+   int remove_user = 0;
+
+   /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
+    * atomic.
+    */
+   uids_mutex_lock();
+
+   local_irq_save(flags);
+
+   if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
+      uid_hash_remove(up);
+      remove_user = 1;
+      spin_unlock_irqrestore(&uidhash_lock, flags);
+   } else {
+      local_irq_restore(flags);
+   }
+
+   if (!remove_user)
+      goto done;
+
+   sysfs_remove_file(kobj, &up->user_attr.attr);
+   kobject_uevent(kobj, KOBJ_REMOVE);
+   kobject_del(kobj);
+
+   sched_destroy_user(up);
+   key_put(up->uid_keyring);
+   key_put(up->session_keyring);
+   kmem_cache_free(uid_cachep, up);
+
+done:
+   uids_mutex_unlock();
+}
+
+/* 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.
+ */
+static inline void free_user(struct user_struct *up, unsigned long flags)
+{
+   /* restore back the count */
+   atomic_inc(&up->__count);
+   spin_unlock_irqrestore(&uidhash_lock, flags);
+
+   INIT_WORK(&up->work, remove_user_sysfs_dir);
+   schedule_work(&up->work);
+}
+
+#else   /* CONFIG_FAIR_USER_SCHED && CONFIG_SYSFS */
+
+static inline int user_kobject_create(struct user_struct *up) { return 0; }
+static inline void uids_mutex_lock(void) { }
+static inline void uids_mutex_unlock(void) { }
+
+/* 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.
+ */
+static inline void free_user(struct user_struct *up, unsigned long flags)
+{
+   uid_hash_remove(up);
+   spin_unlock_irqrestore(&uidhash_lock, flags);
+   sched_destroy_user(up);
+   key_put(up->uid_keyring);
+   key_put(up->session_keyring);
+   kmem_cache_free(uid_cachep, up);
+}
+
+#endif
+
 /*
  * Locate the user_struct for the passed UID.  If found, take a ref on it.  The
  * caller must undo that ref with free_uid().
@@ -106,15 +313,10 @@ void free_uid(struct user_struct *up)
       return;
 
    local_irq_save(flags);
-   if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
-      uid_hash_remove(up);
-      spin_unlock_irqrestore(&uidhash_lock, flags);
-      key_put(up->uid_keyring);
-      key_put(up->session_keyring);
-      kmem_cache_free(uid_cachep, up);
-   } else {
+   if (atomic_dec_and_lock(&up->__count, &uidhash_lock))
+      free_user(up, flags);
+   else
       local_irq_restore(flags);
-   }
 }
 
 struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
@@ -122,6 +324,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
    struct hlist_head *hashent = uidhashentry(ns, uid);
    struct user_struct *up;
 
+   /* Make uid_hash_find() + user_kobject_create() + uid_hash_insert()
+    * atomic.
+    */
+   uids_mutex_lock();
+
    spin_lock_irq(&uidhash_lock);
    up = uid_hash_find(uid, hashent);
    spin_unlock_irq(&uidhash_lock);
@@ -130,8 +337,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
       struct user_struct *new;
 
       new = kmem_cache_alloc(uid_cachep, GFP_KERNEL);
-      if (!new)
+      if (!new) {
+         uids_mutex_unlock();
          return NULL;
+      }
+
       new->uid = uid;
       atomic_set(&new->__count, 1);
       atomic_set(&new->processes, 0);
@@ -141,12 +351,31 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
       atomic_set(&new->inotify_watches, 0);
       atomic_set(&new->inotify_devs, 0);
 #endif
-
+#ifdef CONFIG_POSIX_MQUEUE
       new->mq_bytes = 0;
+#endif
       new->locked_shm = 0;
 
       if (alloc_uid_keyring(new, current) < 0) {
          kmem_cache_free(uid_cachep, new);
+         uids_mutex_unlock();
+         return NULL;
+      }
+
+      if (sched_create_user(new) < 0) {
+         key_put(new->uid_keyring);
+         key_put(new->session_keyring);
+         kmem_cache_free(uid_cachep, new);
+         uids_mutex_unlock();
+         return NULL;
+      }
+
+      if (user_kobject_create(new)) {
+         sched_destroy_user(new);
+         key_put(new->uid_keyring);
+         key_put(new->session_keyring);
+         kmem_cache_free(uid_cachep, new);
+         uids_mutex_unlock();
          return NULL;
       }
 
@@ -157,6 +386,11 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
       spin_lock_irq(&uidhash_lock);
       up = uid_hash_find(uid, hashent);
       if (up) {
+         /* This case is not possible when CONFIG_FAIR_USER_SCHED
+          * is defined, since we serialize alloc_uid() using
+          * uids_mutex. Hence no need to call
+          * sched_destroy_user() or remove_user_sysfs_dir().
+          */
          key_put(new->uid_keyring);
          key_put(new->session_keyring);
          kmem_cache_free(uid_cachep, new);
@@ -167,6 +401,9 @@ struct user_struct * alloc_uid(struct user_namespace *ns, uid_t uid)
       spin_unlock_irq(&uidhash_lock);
 
    }
+
+   uids_mutex_unlock();
+
    return up;
 }
 
@@ -184,6 +421,7 @@ void switch_uid(struct user_struct *new_user)
    atomic_dec(&old_user->processes);
    switch_uid_keyring(new_user);
    current->user = new_user;
+   sched_switch_user(current);
 
    /*
     * We need to synchronize with __sigqueue_alloc()