sched: fix !SYSFS build breakage

When CONFIG_SYSFS is not set, CONFIG_FAIR_USER_SCHED fails to build
with

kernel/built-in.o: In function `uids_kobject_init':
(.init.text+0x1488): undefined reference to `kernel_subsys'
kernel/built-in.o: In function `uids_kobject_init':
(.init.text+0x1490): undefined reference to `kernel_subsys'
kernel/built-in.o: In function `uids_kobject_init':
(.init.text+0x1480): undefined reference to `kernel_subsys'
kernel/built-in.o: In function `uids_kobject_init':
(.init.text+0x1494): undefined reference to `kernel_subsys'

This patch fixes this build error.
Signed-off-by: NSrivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: NDhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -530,10 +530,12 @@ struct user_struct {
 
 #ifdef CONFIG_FAIR_USER_SCHED
 	struct task_group *tg;
+#ifdef CONFIG_SYSFS
 	struct kset kset;
 	struct subsys_attribute user_attr;
 	struct work_struct work;
 #endif
+#endif
 };
 
 #ifdef CONFIG_FAIR_USER_SCHED

kernel/user.c

@@ -87,9 +87,6 @@ static inline struct user_struct *uid_hash_find(uid_t uid,
 
 #ifdef CONFIG_FAIR_USER_SCHED
 
-static struct kobject uids_kobject; /* represents /sys/kernel/uids directory */
-static DEFINE_MUTEX(uids_mutex);
-
 static void sched_destroy_user(struct user_struct *up)
 {
 	sched_destroy_group(up->tg);
@@ -111,6 +108,19 @@ 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);
@@ -257,11 +267,8 @@ static inline void free_user(struct user_struct *up, unsigned long flags)
 	schedule_work(&up->work);
 }
 
-#else	/* CONFIG_FAIR_USER_SCHED */
+#else	/* CONFIG_FAIR_USER_SCHED && CONFIG_SYSFS */
 
-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) { }
 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) { }
@@ -280,7 +287,7 @@ static inline void free_user(struct user_struct *up, unsigned long flags)
 	kmem_cache_free(uid_cachep, up);
 }
 
-#endif	/* CONFIG_FAIR_USER_SCHED */
+#endif
 
 /*
  * Locate the user_struct for the passed UID.  If found, take a ref on it.  The