sched: make plist a library facility

Ingo Molnar wrote:

> here's a new build failure with tip/sched/rt:
>
>   LD      .tmp_vmlinux1
> kernel/built-in.o: In function `set_curr_task_rt':
> sched.c:(.text+0x3675): undefined reference to `plist_del'
> kernel/built-in.o: In function `pick_next_task_rt':
> sched.c:(.text+0x37ce): undefined reference to `plist_del'
> kernel/built-in.o: In function `enqueue_pushable_task':
> sched.c:(.text+0x381c): undefined reference to `plist_del'

Eliminate the plist library kconfig and make it available
unconditionally.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

init/Kconfig

@@ -874,7 +874,6 @@ config SLABINFO
 
 config RT_MUTEXES
 	boolean
-	select PLIST
 
 config BASE_SMALL
 	int

kernel/sched_rt.c

@@ -114,14 +114,23 @@ static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
 
 #else
 
+static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
+{
+}
+
+static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
+{
+}
+
 static inline
-void enqueue_pushable_task(struct rq *rq, struct task_struct *p) {}
-static inline
-void dequeue_pushable_task(struct rq *rq, struct task_struct *p) {}
-static inline
-void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
+void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
+{
+}
+
 static inline
-void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
+void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
+{
+}
 
 #endif /* CONFIG_SMP */
 

lib/Kconfig

@@ -136,12 +136,6 @@ config TEXTSEARCH_BM
 config TEXTSEARCH_FSM
 	tristate
 
-#
-# plist support is select#ed if needed
-#
-config PLIST
-	boolean
-
 config HAS_IOMEM
 	boolean
 	depends on !NO_IOMEM

lib/Makefile

@@ -11,7 +11,8 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 rbtree.o radix-tree.o dump_stack.o \
 	 idr.o int_sqrt.o extable.o prio_tree.o \
 	 sha1.o irq_regs.o reciprocal_div.o argv_split.o \
-	 proportions.o prio_heap.o ratelimit.o show_mem.o is_single_threaded.o
+	 proportions.o prio_heap.o ratelimit.o show_mem.o \
+	 is_single_threaded.o plist.o
 
 lib-$(CONFIG_MMU) += ioremap.o
 lib-$(CONFIG_SMP) += cpumask.o
@@ -40,7 +41,6 @@ lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o
 lib-$(CONFIG_GENERIC_FIND_LAST_BIT) += find_last_bit.o
 obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
 obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o
-obj-$(CONFIG_PLIST) += plist.o
 obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
 obj-$(CONFIG_DEBUG_LIST) += list_debug.o
 obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o