core: 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 determined (since it's an implied address conversion through
segment prefixes).  Therefore apply this only to uses of __get_cpu_var
where the address of the variable is not used.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 18 insertions, 18 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 6e3c41a..8037a86 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -116,12 +116,12 @@ static void __touch_watchdog(void)
 {
 	int this_cpu = smp_processor_id();
 
-	__get_cpu_var(watchdog_touch_ts) = get_timestamp(this_cpu);
+	__this_cpu_write(watchdog_touch_ts, get_timestamp(this_cpu));
 }
 
 void touch_softlockup_watchdog(void)
 {
-	__raw_get_cpu_var(watchdog_touch_ts) = 0;
+	__this_cpu_write(watchdog_touch_ts, 0);
 }
 EXPORT_SYMBOL(touch_softlockup_watchdog);
 
@@ -165,12 +165,12 @@ void touch_softlockup_watchdog_sync(void)
 /* watchdog detector functions */
 static int is_hardlockup(void)
 {
-	unsigned long hrint = __get_cpu_var(hrtimer_interrupts);
+	unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
 
-	if (__get_cpu_var(hrtimer_interrupts_saved) == hrint)
+	if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
 		return 1;
 
-	__get_cpu_var(hrtimer_interrupts_saved) = hrint;
+	__this_cpu_write(hrtimer_interrupts_saved, hrint);
 	return 0;
 }
 #endif
@@ -203,8 +203,8 @@ static void watchdog_overflow_callback(struct perf_event *event, int nmi,
 	/* Ensure the watchdog never gets throttled */
 	event->hw.interrupts = 0;
 
-	if (__get_cpu_var(watchdog_nmi_touch) == true) {
-		__get_cpu_var(watchdog_nmi_touch) = false;
+	if (__this_cpu_read(watchdog_nmi_touch) == true) {
+		__this_cpu_write(watchdog_nmi_touch, false);
 		return;
 	}
 
@@ -218,7 +218,7 @@ static void watchdog_overflow_callback(struct perf_event *event, int nmi,
 		int this_cpu = smp_processor_id();
 
 		/* only print hardlockups once */
-		if (__get_cpu_var(hard_watchdog_warn) == true)
+		if (__this_cpu_read(hard_watchdog_warn) == true)
 			return;
 
 		if (hardlockup_panic)
@@ -226,16 +226,16 @@ static void watchdog_overflow_callback(struct perf_event *event, int nmi,
 		else
 			WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
 
-		__get_cpu_var(hard_watchdog_warn) = true;
+		__this_cpu_write(hard_watchdog_warn, true);
 		return;
 	}
 
-	__get_cpu_var(hard_watchdog_warn) = false;
+	__this_cpu_write(hard_watchdog_warn, false);
 	return;
 }
 static void watchdog_interrupt_count(void)
 {
-	__get_cpu_var(hrtimer_interrupts)++;
+	__this_cpu_inc(hrtimer_interrupts);
 }
 #else
 static inline void watchdog_interrupt_count(void) { return; }
@@ -244,7 +244,7 @@ static inline void watchdog_interrupt_count(void) { return; }
 /* watchdog kicker functions */
 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 {
-	unsigned long touch_ts = __get_cpu_var(watchdog_touch_ts);
+	unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
 	struct pt_regs *regs = get_irq_regs();
 	int duration;
 
@@ -252,18 +252,18 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 	watchdog_interrupt_count();
 
 	/* kick the softlockup detector */
-	wake_up_process(__get_cpu_var(softlockup_watchdog));
+	wake_up_process(__this_cpu_read(softlockup_watchdog));
 
 	/* .. and repeat */
 	hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
 
 	if (touch_ts == 0) {
-		if (unlikely(__get_cpu_var(softlockup_touch_sync))) {
+		if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
 			/*
 			 * If the time stamp was touched atomically
 			 * make sure the scheduler tick is up to date.
 			 */
-			__get_cpu_var(softlockup_touch_sync) = false;
+			__this_cpu_write(softlockup_touch_sync, false);
 			sched_clock_tick();
 		}
 		__touch_watchdog();
@@ -279,7 +279,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 	duration = is_softlockup(touch_ts);
 	if (unlikely(duration)) {
 		/* only warn once */
-		if (__get_cpu_var(soft_watchdog_warn) == true)
+		if (__this_cpu_read(soft_watchdog_warn) == true)
 			return HRTIMER_RESTART;
 
 		printk(KERN_ERR "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
@@ -294,9 +294,9 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 
 		if (softlockup_panic)
 			panic("softlockup: hung tasks");
-		__get_cpu_var(soft_watchdog_warn) = true;
+		__this_cpu_write(soft_watchdog_warn, true);
 	} else
-		__get_cpu_var(soft_watchdog_warn) = false;
+		__this_cpu_write(soft_watchdog_warn, false);
 
 	return HRTIMER_RESTART;
 }