sched: Remove USER_SCHED

Remove the USER_SCHED feature. It has been scheduled to be removed in
2.6.34 as per http://marc.info/?l=linux-kernel&m=125728479022976&w=2

Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1263990378.24844.3.camel@localhost>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

7 files changed, 38 insertions, 504 deletions

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 870d190fe617..04a3fc3d139b 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -6,21 +6,6 @@ be removed from this file.
 
 ---------------------------
 
-What:   USER_SCHED
-When:   2.6.34
-
-Why:    USER_SCHED was implemented as a proof of concept for group scheduling.
-        The effect of USER_SCHED can already be achieved from userspace with
-        the help of libcgroup. The removal of USER_SCHED will also simplify
-        the scheduler code with the removal of one major ifdef. There are also
-        issues USER_SCHED has with USER_NS. A decision was taken not to fix
-        those and instead remove USER_SCHED. Also new group scheduling
-        features will not be implemented for USER_SCHED.
-
-Who:    Dhaval Giani <dhaval@linux.vnet.ibm.com>
-
----------------------------
-
 What:   PRISM54
 When:   2.6.34
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 50d685cde70e..8b079735ae5f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -731,14 +731,6 @@ struct user_struct {
         uid_t uid;
         struct user_namespace *user_ns;
 
-#ifdef CONFIG_USER_SCHED
-        struct task_group *tg;
-#ifdef CONFIG_SYSFS
-        struct kobject kobj;
-        struct delayed_work work;
-#endif
-#endif
-
 #ifdef CONFIG_PERF_EVENTS
         atomic_long_t locked_vm;
 #endif
@@ -2502,13 +2494,9 @@ extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
 
 extern void normalize_rt_tasks(void);
 
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
 
 extern struct task_group init_task_group;
-#ifdef CONFIG_USER_SCHED
-extern struct task_group root_task_group;
-extern void set_tg_uid(struct user_struct *user);
-#endif
 
 extern struct task_group *sched_create_group(struct task_group *parent);
 extern void sched_destroy_group(struct task_group *tg);
diff --git a/init/Kconfig b/init/Kconfig
index a23da9f01803..e9fa3007a6fc 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -435,57 +435,6 @@ config LOG_BUF_SHIFT
 config HAVE_UNSTABLE_SCHED_CLOCK
         bool
 
-config GROUP_SCHED
-        bool "Group CPU scheduler"
-        depends on EXPERIMENTAL
-        default n
-        help
-          This feature lets CPU scheduler recognize task groups and control CPU
-          bandwidth allocation to such task groups.
-          In order to create a group from arbitrary set of processes, use
-          CONFIG_CGROUPS. (See Control Group support.)
-
-config FAIR_GROUP_SCHED
-        bool "Group scheduling for SCHED_OTHER"
-        depends on GROUP_SCHED
-        default GROUP_SCHED
-
-config RT_GROUP_SCHED
-        bool "Group scheduling for SCHED_RR/FIFO"
-        depends on EXPERIMENTAL
-        depends on GROUP_SCHED
-        default n
-        help
-          This feature lets you explicitly allocate real CPU bandwidth
-          to users or control groups (depending on the "Basis for grouping tasks"
-          setting below. If enabled, it will also make it impossible to
-          schedule realtime tasks for non-root users until you allocate
-          realtime bandwidth for them.
-          See Documentation/scheduler/sched-rt-group.txt for more information.
-
-choice
-        depends on GROUP_SCHED
-        prompt "Basis for grouping tasks"
-        default USER_SCHED
-
-config USER_SCHED
-        bool "user id"
-        help
-          This option will choose userid as the basis for grouping
-          tasks, thus providing equal CPU bandwidth to each user.
-
-config CGROUP_SCHED
-        bool "Control groups"
-        depends on CGROUPS
-        help
-          This option allows you to create arbitrary task groups
-          using the "cgroup" pseudo filesystem and control
-          the cpu bandwidth allocated to each such task group.
-          Refer to Documentation/cgroups/cgroups.txt for more
-          information on "cgroup" pseudo filesystem.
-
-endchoice
-
 menuconfig CGROUPS
         boolean "Control Group support"
         help
@@ -606,6 +555,36 @@ config CGROUP_MEM_RES_CTLR_SWAP
           Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
           size is 4096bytes, 512k per 1Gbytes of swap.
 
+menuconfig CGROUP_SCHED
+        bool "Group CPU scheduler"
+        depends on EXPERIMENTAL && CGROUPS
+        default n
+        help
+          This feature lets CPU scheduler recognize task groups and control CPU
+          bandwidth allocation to such task groups. It uses cgroups to group
+          tasks.
+
+if CGROUP_SCHED
+config FAIR_GROUP_SCHED
+        bool "Group scheduling for SCHED_OTHER"
+        depends on CGROUP_SCHED
+        default CGROUP_SCHED
+
+config RT_GROUP_SCHED
+        bool "Group scheduling for SCHED_RR/FIFO"
+        depends on EXPERIMENTAL
+        depends on CGROUP_SCHED
+        default n
+        help
+          This feature lets you explicitly allocate real CPU bandwidth
+          to users or control groups (depending on the "Basis for grouping tasks"
+          setting below. If enabled, it will also make it impossible to
+          schedule realtime tasks for non-root users until you allocate
+          realtime bandwidth for them.
+          See Documentation/scheduler/sched-rt-group.txt for more information.
+
+endif #CGROUP_SCHED
+
 endif # CGROUPS
 
 config MM_OWNER
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 3feaf5a74514..6b1ccc3f0205 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -197,16 +197,8 @@ static int __init ksysfs_init(void)
                         goto group_exit;
         }
 
-        /* create the /sys/kernel/uids/ directory */
-        error = uids_sysfs_init();
-        if (error)
-                goto notes_exit;
-
         return 0;
 
-notes_exit:
-        if (notes_size > 0)
-                sysfs_remove_bin_file(kernel_kobj, &notes_attr);
 group_exit:
         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 kset_exit:
diff --git a/kernel/sched.c b/kernel/sched.c
index c0be07932a8d..41e76d325648 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -233,7 +233,7 @@ static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
  */
 static DEFINE_MUTEX(sched_domains_mutex);
 
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
 
 #include <linux/cgroup.h>
 
@@ -243,13 +243,7 @@ static LIST_HEAD(task_groups);
 
 /* task group related information */
 struct task_group {
-#ifdef CONFIG_CGROUP_SCHED
         struct cgroup_subsys_state css;
-#endif
-
-#ifdef CONFIG_USER_SCHED
-        uid_t uid;
-#endif
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
         /* schedulable entities of this group on each cpu */
@@ -274,35 +268,7 @@ struct task_group {
         struct list_head children;
 };
 
-#ifdef CONFIG_USER_SCHED
-
-/* Helper function to pass uid information to create_sched_user() */
-void set_tg_uid(struct user_struct *user)
-{
-        user->tg->uid = user->uid;
-}
-
-/*
- * Root task group.
- *      Every UID task group (including init_task_group aka UID-0) will
- *      be a child to this group.
- */
-struct task_group root_task_group;
-
-#ifdef CONFIG_FAIR_GROUP_SCHED
-/* Default task group's sched entity on each cpu */
-static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
-/* Default task group's cfs_rq on each cpu */
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct cfs_rq, init_tg_cfs_rq);
-#endif /* CONFIG_FAIR_GROUP_SCHED */
-
-#ifdef CONFIG_RT_GROUP_SCHED
-static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
-static DEFINE_PER_CPU_SHARED_ALIGNED(struct rt_rq, init_rt_rq_var);
-#endif /* CONFIG_RT_GROUP_SCHED */
-#else /* !CONFIG_USER_SCHED */
 #define root_task_group init_task_group
-#endif /* CONFIG_USER_SCHED */
 
 /* task_group_lock serializes add/remove of task groups and also changes to
  * a task group's cpu shares.
@@ -318,11 +284,7 @@ static int root_task_group_empty(void)
 }
 #endif
 
-#ifdef CONFIG_USER_SCHED
-# define INIT_TASK_GROUP_LOAD   (2*NICE_0_LOAD)
-#else /* !CONFIG_USER_SCHED */
 # define INIT_TASK_GROUP_LOAD   NICE_0_LOAD
-#endif /* CONFIG_USER_SCHED */
 
 /*
  * A weight of 0 or 1 can cause arithmetics problems.
@@ -348,11 +310,7 @@ static inline struct task_group *task_group(struct task_struct *p)
 {
         struct task_group *tg;
 
-#ifdef CONFIG_USER_SCHED
-        rcu_read_lock();
-        tg = __task_cred(p)->user->tg;
-        rcu_read_unlock();
-#elif defined(CONFIG_CGROUP_SCHED)
+#ifdef CONFIG_CGROUP_SCHED
         tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
                                 struct task_group, css);
 #else
@@ -383,7 +341,7 @@ static inline struct task_group *task_group(struct task_struct *p)
         return NULL;
 }
 
-#endif  /* CONFIG_GROUP_SCHED */
+#endif  /* CONFIG_CGROUP_SCHED */
 
 /* CFS-related fields in a runqueue */
 struct cfs_rq {
@@ -7678,9 +7636,6 @@ void __init sched_init(void)
 #ifdef CONFIG_RT_GROUP_SCHED
         alloc_size += 2 * nr_cpu_ids * sizeof(void **);
 #endif
-#ifdef CONFIG_USER_SCHED
-        alloc_size *= 2;
-#endif
 #ifdef CONFIG_CPUMASK_OFFSTACK
         alloc_size += num_possible_cpus() * cpumask_size();
 #endif
@@ -7694,13 +7649,6 @@ void __init sched_init(void)
                 init_task_group.cfs_rq = (struct cfs_rq **)ptr;
                 ptr += nr_cpu_ids * sizeof(void **);
 
-#ifdef CONFIG_USER_SCHED
-                root_task_group.se = (struct sched_entity **)ptr;
-                ptr += nr_cpu_ids * sizeof(void **);
-
-                root_task_group.cfs_rq = (struct cfs_rq **)ptr;
-                ptr += nr_cpu_ids * sizeof(void **);
-#endif /* CONFIG_USER_SCHED */
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 #ifdef CONFIG_RT_GROUP_SCHED
                 init_task_group.rt_se = (struct sched_rt_entity **)ptr;
@@ -7709,13 +7657,6 @@ void __init sched_init(void)
                 init_task_group.rt_rq = (struct rt_rq **)ptr;
                 ptr += nr_cpu_ids * sizeof(void **);
 
-#ifdef CONFIG_USER_SCHED
-                root_task_group.rt_se = (struct sched_rt_entity **)ptr;
-                ptr += nr_cpu_ids * sizeof(void **);
-
-                root_task_group.rt_rq = (struct rt_rq **)ptr;
-                ptr += nr_cpu_ids * sizeof(void **);
-#endif /* CONFIG_USER_SCHED */
 #endif /* CONFIG_RT_GROUP_SCHED */
 #ifdef CONFIG_CPUMASK_OFFSTACK
                 for_each_possible_cpu(i) {
@@ -7735,22 +7676,13 @@ void __init sched_init(void)
 #ifdef CONFIG_RT_GROUP_SCHED
         init_rt_bandwidth(&init_task_group.rt_bandwidth,
                         global_rt_period(), global_rt_runtime());
-#ifdef CONFIG_USER_SCHED
-        init_rt_bandwidth(&root_task_group.rt_bandwidth,
-                        global_rt_period(), RUNTIME_INF);
-#endif /* CONFIG_USER_SCHED */
 #endif /* CONFIG_RT_GROUP_SCHED */
 
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
         list_add(&init_task_group.list, &task_groups);
         INIT_LIST_HEAD(&init_task_group.children);
 
-#ifdef CONFIG_USER_SCHED
-        INIT_LIST_HEAD(&root_task_group.children);
-        init_task_group.parent = &root_task_group;
-        list_add(&init_task_group.siblings, &root_task_group.children);
-#endif /* CONFIG_USER_SCHED */
-#endif /* CONFIG_GROUP_SCHED */
+#endif /* CONFIG_CGROUP_SCHED */
 
 #if defined CONFIG_FAIR_GROUP_SCHED && defined CONFIG_SMP
         update_shares_data = __alloc_percpu(nr_cpu_ids * sizeof(unsigned long),
@@ -7790,25 +7722,6 @@ void __init sched_init(void)
                  * directly in rq->cfs (i.e init_task_group->se[] = NULL).
                  */
                 init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
-#elif defined CONFIG_USER_SCHED
-                root_task_group.shares = NICE_0_LOAD;
-                init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, 0, NULL);
-                /*
-                 * In case of task-groups formed thr' the user id of tasks,
-                 * init_task_group represents tasks belonging to root user.
-                 * Hence it forms a sibling of all subsequent groups formed.
-                 * In this case, init_task_group gets only a fraction of overall
-                 * system cpu resource, based on the weight assigned to root
-                 * user's cpu share (INIT_TASK_GROUP_LOAD). This is accomplished
-                 * by letting tasks of init_task_group sit in a separate cfs_rq
-                 * (init_tg_cfs_rq) and having one entity represent this group of
-                 * tasks in rq->cfs (i.e init_task_group->se[] != NULL).
-                 */
-                init_tg_cfs_entry(&init_task_group,
-                                &per_cpu(init_tg_cfs_rq, i),
-                                &per_cpu(init_sched_entity, i), i, 1,
-                                root_task_group.se[i]);
-
 #endif
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 
@@ -7817,12 +7730,6 @@ void __init sched_init(void)
                 INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
 #ifdef CONFIG_CGROUP_SCHED
                 init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
-#elif defined CONFIG_USER_SCHED
-                init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, 0, NULL);
-                init_tg_rt_entry(&init_task_group,
-                                &per_cpu(init_rt_rq_var, i),
-                                &per_cpu(init_sched_rt_entity, i), i, 1,
-                                root_task_group.rt_se[i]);
 #endif
 #endif
 
@@ -8218,7 +8125,7 @@ static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
 }
 #endif /* CONFIG_RT_GROUP_SCHED */
 
-#ifdef CONFIG_GROUP_SCHED
+#ifdef CONFIG_CGROUP_SCHED
 static void free_sched_group(struct task_group *tg)
 {
         free_fair_sched_group(tg);
@@ -8327,7 +8234,7 @@ void sched_move_task(struct task_struct *tsk)
 
         task_rq_unlock(rq, &flags);
 }
-#endif /* CONFIG_GROUP_SCHED */
+#endif /* CONFIG_CGROUP_SCHED */
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 static void __set_se_shares(struct sched_entity *se, unsigned long shares)
@@ -8469,13 +8376,6 @@ static int tg_schedulable(struct task_group *tg, void *data)
                 runtime = d->rt_runtime;
         }
 
-#ifdef CONFIG_USER_SCHED
-        if (tg == &root_task_group) {
-                period = global_rt_period();
-                runtime = global_rt_runtime();
-        }
-#endif
-
         /*
          * Cannot have more runtime than the period.
          */
diff --git a/kernel/sys.c b/kernel/sys.c
index 26a6b73a6b85..f75bf0936f47 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -569,11 +569,6 @@ static int set_user(struct cred *new)
         if (!new_user)
                 return -EAGAIN;
 
-        if (!task_can_switch_user(new_user, current)) {
-                free_uid(new_user);
-                return -EINVAL;
-        }
-
         if (atomic_read(&new_user->processes) >=
                                 current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
                         new_user != INIT_USER) {
diff --git a/kernel/user.c b/kernel/user.c
index 46d0165ca70c..766467b3bcb7 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -56,9 +56,6 @@ struct user_struct root_user = {
         .sigpending     = ATOMIC_INIT(0),
         .locked_shm     = 0,
         .user_ns        = &init_user_ns,
-#ifdef CONFIG_USER_SCHED
-        .tg             = &init_task_group,
-#endif
 };
 
 /*
@@ -75,268 +72,6 @@ static void uid_hash_remove(struct user_struct *up)
         put_user_ns(up->user_ns);
 }
 
-#ifdef CONFIG_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(&root_task_group);
-        if (IS_ERR(up->tg))
-                rc = -ENOMEM;
-
-        set_tg_uid(up);
-
-        return rc;
-}
-
-#else   /* CONFIG_USER_SCHED */
-
-static void sched_destroy_user(struct user_struct *up) { }
-static int sched_create_user(struct user_struct *up) { return 0; }
-
-#endif  /* CONFIG_USER_SCHED */
-
-#if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
-
-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) {
-                        /* possibly resurrect an "almost deleted" object */
-                        if (atomic_inc_return(&user->__count) == 1)
-                                cancel_delayed_work(&user->work);
-                        return user;
-                }
-        }
-
-        return NULL;
-}
-
-static struct kset *uids_kset; /* represents the /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);
-}
-
-/* uid directory attributes */
-#ifdef CONFIG_FAIR_GROUP_SCHED
-static ssize_t cpu_shares_show(struct kobject *kobj,
-                               struct kobj_attribute *attr,
-                               char *buf)
-{
-        struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-
-        return sprintf(buf, "%lu\n", sched_group_shares(up->tg));
-}
-
-static ssize_t cpu_shares_store(struct kobject *kobj,
-                                struct kobj_attribute *attr,
-                                const char *buf, size_t size)
-{
-        struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-        unsigned long shares;
-        int rc;
-
-        sscanf(buf, "%lu", &shares);
-
-        rc = sched_group_set_shares(up->tg, shares);
-
-        return (rc ? rc : size);
-}
-
-static struct kobj_attribute cpu_share_attr =
-        __ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store);
-#endif
-
-#ifdef CONFIG_RT_GROUP_SCHED
-static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
-                                   struct kobj_attribute *attr,
-                                   char *buf)
-{
-        struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-
-        return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg));
-}
-
-static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
-                                    struct kobj_attribute *attr,
-                                    const char *buf, size_t size)
-{
-        struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-        unsigned long rt_runtime;
-        int rc;
-
-        sscanf(buf, "%ld", &rt_runtime);
-
-        rc = sched_group_set_rt_runtime(up->tg, rt_runtime);
-
-        return (rc ? rc : size);
-}
-
-static struct kobj_attribute cpu_rt_runtime_attr =
-        __ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store);
-
-static ssize_t cpu_rt_period_show(struct kobject *kobj,
-                                   struct kobj_attribute *attr,
-                                   char *buf)
-{
-        struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-
-        return sprintf(buf, "%lu\n", sched_group_rt_period(up->tg));
-}
-
-static ssize_t cpu_rt_period_store(struct kobject *kobj,
-                                    struct kobj_attribute *attr,
-                                    const char *buf, size_t size)
-{
-        struct user_struct *up = container_of(kobj, struct user_struct, kobj);
-        unsigned long rt_period;
-        int rc;
-
-        sscanf(buf, "%lu", &rt_period);
-
-        rc = sched_group_set_rt_period(up->tg, rt_period);
-
-        return (rc ? rc : size);
-}
-
-static struct kobj_attribute cpu_rt_period_attr =
-        __ATTR(cpu_rt_period, 0644, cpu_rt_period_show, cpu_rt_period_store);
-#endif
-
-/* default attributes per uid directory */
-static struct attribute *uids_attributes[] = {
-#ifdef CONFIG_FAIR_GROUP_SCHED
-        &cpu_share_attr.attr,
-#endif
-#ifdef CONFIG_RT_GROUP_SCHED
-        &cpu_rt_runtime_attr.attr,
-        &cpu_rt_period_attr.attr,
-#endif
-        NULL
-};
-
-/* the lifetime of user_struct is not managed by the core (now) */
-static void uids_release(struct kobject *kobj)
-{
-        return;
-}
-
-static struct kobj_type uids_ktype = {
-        .sysfs_ops = &kobj_sysfs_ops,
-        .default_attrs = uids_attributes,
-        .release = uids_release,
-};
-
-/*
- * Create /sys/kernel/uids/<uid>/cpu_share file for this user
- * We do not create this file for users in a user namespace (until
- * sysfs tagging is implemented).
- *
- * See Documentation/scheduler/sched-design-CFS.txt for ramifications.
- */
-static int uids_user_create(struct user_struct *up)
-{
-        struct kobject *kobj = &up->kobj;
-        int error;
-
-        memset(kobj, 0, sizeof(struct kobject));
-        if (up->user_ns != &init_user_ns)
-                return 0;
-        kobj->kset = uids_kset;
-        error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
-        if (error) {
-                kobject_put(kobj);
-                goto done;
-        }
-
-        kobject_uevent(kobj, KOBJ_ADD);
-done:
-        return error;
-}
-
-/* create these entries in sysfs:
- *      "/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_sysfs_init(void)
-{
-        uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
-        if (!uids_kset)
-                return -ENOMEM;
-
-        return uids_user_create(&root_user);
-}
-
-/* delayed work function to remove sysfs directory for a user and free up
- * corresponding structures.
- */
-static void cleanup_user_struct(struct work_struct *w)
-{
-        struct user_struct *up = container_of(w, struct user_struct, work.work);
-        unsigned long flags;
-        int remove_user = 0;
-
-        /* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
-         * atomic.
-         */
-        uids_mutex_lock();
-
-        spin_lock_irqsave(&uidhash_lock, flags);
-        if (atomic_read(&up->__count) == 0) {
-                uid_hash_remove(up);
-                remove_user = 1;
-        }
-        spin_unlock_irqrestore(&uidhash_lock, flags);
-
-        if (!remove_user)
-                goto done;
-
-        if (up->user_ns == &init_user_ns) {
-                kobject_uevent(&up->kobj, KOBJ_REMOVE);
-                kobject_del(&up->kobj);
-                kobject_put(&up->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 void free_user(struct user_struct *up, unsigned long flags)
-{
-        INIT_DELAYED_WORK(&up->work, cleanup_user_struct);
-        schedule_delayed_work(&up->work, msecs_to_jiffies(1000));
-        spin_unlock_irqrestore(&uidhash_lock, flags);
-}
-
-#else   /* CONFIG_USER_SCHED && CONFIG_SYSFS */
-
 static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
 {
         struct user_struct *user;
@@ -352,11 +87,6 @@ static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
         return NULL;
 }
 
-int uids_sysfs_init(void) { return 0; }
-static inline int uids_user_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.
@@ -365,32 +95,11 @@ static 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
-
-#if defined(CONFIG_RT_GROUP_SCHED) && defined(CONFIG_USER_SCHED)
-/*
- * We need to check if a setuid can take place. This function should be called
- * before successfully completing the setuid.
- */
-int task_can_switch_user(struct user_struct *up, struct task_struct *tsk)
-{
-
-        return sched_rt_can_attach(up->tg, tsk);
-
-}
-#else
-int task_can_switch_user(struct user_struct *up, struct task_struct *tsk)
-{
-        return 1;
-}
-#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().
@@ -431,8 +140,6 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
         /* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
          * atomic.
          */
-        uids_mutex_lock();
-
         spin_lock_irq(&uidhash_lock);
         up = uid_hash_find(uid, hashent);
         spin_unlock_irq(&uidhash_lock);
@@ -445,14 +152,8 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
                 new->uid = uid;
                 atomic_set(&new->__count, 1);
 
-                if (sched_create_user(new) < 0)
-                        goto out_free_user;
-
                 new->user_ns = get_user_ns(ns);
 
-                if (uids_user_create(new))
-                        goto out_destoy_sched;
-
                 /*
                  * Before adding this, check whether we raced
                  * on adding the same user already..
@@ -475,17 +176,11 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
                 spin_unlock_irq(&uidhash_lock);
         }
 
-        uids_mutex_unlock();
-
         return up;
 
-out_destoy_sched:
-        sched_destroy_user(new);
         put_user_ns(new->user_ns);
-out_free_user:
         kmem_cache_free(uid_cachep, new);
 out_unlock:
-        uids_mutex_unlock();
         return NULL;
 }