x86/bitops.h: Remove unused smp_mb__* macros

Signed-off-by: Keir Fraser <keir@xen.org>

xen/arch/x86/acpi/cpu_idle.c

@@ -220,12 +220,6 @@ static uint64_t acpi_pm_ticks_elapsed(uint64_t t1, uint64_t t2)
         return ((0xFFFFFFFF - t1) + t2 +1);
 }
 
-static void acpi_safe_halt(void)
-{
-    smp_mb__after_clear_bit();
-    safe_halt();
-}
-
 #define MWAIT_ECX_INTERRUPT_BREAK   (0x1)
 
 /*
@@ -296,7 +290,7 @@ static void acpi_idle_do_entry(struct acpi_processor_cx *cx)
         unused = inl(pmtmr_ioport);
         return;
     case ACPI_CSTATE_EM_HALT:
-        acpi_safe_halt();
+        safe_halt();
         local_irq_disable();
         return;
     }
@@ -402,7 +396,7 @@ static void acpi_processor_idle(void)
         if ( pm_idle_save )
             pm_idle_save();
         else
-            acpi_safe_halt();
+            safe_halt();
         return;
     }
 

xen/include/asm-x86/bitops.h

@@ -70,10 +70,7 @@ static inline void __set_bit(int nr, volatile void *addr)
  * @nr: Bit to clear
  * @addr: Address to start counting from
  *
- * clear_bit() is atomic and may not be reordered.  However, it does
- * not contain a memory barrier, so if it is used for locking purposes,
- * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
- * in order to ensure changes are visible on other processors.
+ * clear_bit() is atomic and may not be reordered.
  */
 static inline void clear_bit(int nr, volatile void *addr)
 {
@@ -108,9 +105,6 @@ static inline void __clear_bit(int nr, volatile void *addr)
     __clear_bit(nr, addr);                              \
 })
 
-#define smp_mb__before_clear_bit() ((void)0)
-#define smp_mb__after_clear_bit()  ((void)0)
-
 /**
  * __change_bit - Toggle a bit in memory
  * @nr: the bit to set