drivers: Replace __get_cpu_var with __this_cpu_read if not used for an address.

__get_cpu_var() can be replaced with this_cpu_read and will then use a single
read instruction with implied address calculation to access the correct per cpu
instance.

However, the address of a per cpu variable passed to __this_cpu_read() cannot be
determed (since its an implied address conversion through segment prefixes).
Therefore apply this only to uses of __get_cpu_var where the addres of the
variable is not used.

V3->V4:
	- Move one instance of this_cpu_inc_return to a later patch
	  so that this one can go in without percpu infrastructrure
	  changes.

Sedat: fixed compile failure caused by an extra ')'.

Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

drivers/acpi/processor_idle.c

@@ -746,7 +746,7 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
 	struct acpi_processor *pr;
 	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
 
-	pr = __get_cpu_var(processors);
+	pr = __this_cpu_read(processors);
 
 	if (unlikely(!pr))
 		return 0;
@@ -787,7 +787,7 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
 	s64 idle_time_ns;
 	s64 idle_time;
 
-	pr = __get_cpu_var(processors);
+	pr = __this_cpu_read(processors);
 
 	if (unlikely(!pr))
 		return 0;
@@ -864,7 +864,7 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
 	s64 idle_time;
 
 
-	pr = __get_cpu_var(processors);
+	pr = __this_cpu_read(processors);
 
 	if (unlikely(!pr))
 		return 0;

drivers/cpuidle/cpuidle.c

@@ -49,7 +49,7 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
  */
 static void cpuidle_idle_call(void)
 {
-	struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
+	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
 	struct cpuidle_state *target_state;
 	int next_state;
 

drivers/s390/cio/cio.c

@@ -619,7 +619,7 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
 	s390_idle_check(regs, S390_lowcore.int_clock,
 			S390_lowcore.async_enter_timer);
 	irq_enter();
-	__get_cpu_var(s390_idle).nohz_delay = 1;
+	__this_cpu_write(s390_idle.nohz_delay, 1);
 	if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
 		/* Serve timer interrupts first. */
 		clock_comparator_work();

drivers/staging/speakup/fakekey.c

@@ -78,10 +78,10 @@ void speakup_fake_down_arrow(void)
 	/* don't change CPU */
 	preempt_disable();
 
-	__get_cpu_var(reporting_keystroke) = true;
+	__this_cpu_write(reporting_keystroke, true);
 	input_report_key(virt_keyboard, KEY_DOWN, PRESSED);
 	input_report_key(virt_keyboard, KEY_DOWN, RELEASED);
-	__get_cpu_var(reporting_keystroke) = false;
+	__this_cpu_write(reporting_keystroke, false);
 
 	/* reenable preemption */
 	preempt_enable();