x86_32: clean up play_dead

The removal of the CPU from the various maps was redundant as it already
happened in cpu_disable.

After cleaning this up, cpu_uninit only resets the tlb state, so rename
it and create a noop version for the X86_64 case (so the two play_deads
can be unified later).

Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/common.c

@@ -714,14 +714,10 @@ void __cpuinit cpu_init(void)
 	mxcsr_feature_mask_init();
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-void __cpuinit cpu_uninit(void)
+void reset_lazy_tlbstate(void)
 {
 	int cpu = raw_smp_processor_id();
-	cpu_clear(cpu, cpu_initialized);
 
-	/* lazy TLB state */
 	per_cpu(cpu_tlbstate, cpu).state = 0;
 	per_cpu(cpu_tlbstate, cpu).active_mm = &init_mm;
 }
-#endif

arch/x86/kernel/process_32.c

@@ -75,26 +75,17 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
 #ifdef CONFIG_HOTPLUG_CPU
 #include <asm/nmi.h>
 
-static void cpu_exit_clear(void)
+/* We don't actually take CPU down, just spin without interrupts. */
+void native_play_dead(void)
 {
 	int cpu = raw_smp_processor_id();
 
 	idle_task_exit();
 
-	cpu_uninit();
-	irq_ctx_exit(cpu);
+	reset_lazy_tlbstate();
 
-	cpu_clear(cpu, cpu_callout_map);
-	cpu_clear(cpu, cpu_callin_map);
-
-	numa_remove_cpu(cpu);
-}
+	irq_ctx_exit(cpu);
 
-/* We don't actually take CPU down, just spin without interrupts. */
-void native_play_dead(void)
-{
-	/* This must be done before dead CPU ack */
-	cpu_exit_clear();
 	mb();
 	/* Ack it */
 	__get_cpu_var(cpu_state) = CPU_DEAD;

include/asm-x86/smp.h

@@ -221,7 +221,12 @@ static inline int hard_smp_processor_id(void)
 #endif /* CONFIG_X86_LOCAL_APIC */
 
 #ifdef CONFIG_HOTPLUG_CPU
-extern void cpu_uninit(void);
+#ifdef CONFIG_X86_32
+extern void reset_lazy_tlbstate(void);
+#else
+static inline void reset_lazy_tlbstate(void)
+{ }
+#endif /* CONFIG_X86_32 */
 #endif
 
 #endif /* __ASSEMBLY__ */