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>

9 files changed, 49 insertions, 49 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 676149a4ac5f..89c74861a3da 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -69,7 +69,7 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
 
                 list_del_rcu(&p->tasks);
                 list_del_init(&p->sibling);
-                __get_cpu_var(process_counts)--;
+                __this_cpu_dec(process_counts);
         }
         list_del_rcu(&p->thread_group);
 }
diff --git a/kernel/fork.c b/kernel/fork.c
index 3b159c5991b7..e05e27de67df 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1282,7 +1282,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                         attach_pid(p, PIDTYPE_SID, task_session(current));
                         list_add_tail(&p->sibling, &p->real_parent->children);
                         list_add_tail_rcu(&p->tasks, &init_task.tasks);
-                        __get_cpu_var(process_counts)++;
+                        __this_cpu_inc(process_counts);
                 }
                 attach_pid(p, PIDTYPE_PID, pid);
                 nr_threads++;
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 72206cf5c6cf..29de5ae4ca95 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -497,7 +497,7 @@ static inline int hrtimer_is_hres_enabled(void)
  */
 static inline int hrtimer_hres_active(void)
 {
-        return __get_cpu_var(hrtimer_bases).hres_active;
+        return __this_cpu_read(hrtimer_bases.hres_active);
 }
 
 /*
diff --git a/kernel/printk.c b/kernel/printk.c
index 9a2264fc42ca..b032317f9964 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1074,8 +1074,8 @@ static DEFINE_PER_CPU(int, printk_pending);
 
 void printk_tick(void)
 {
-        if (__get_cpu_var(printk_pending)) {
-                __get_cpu_var(printk_pending) = 0;
+        if (__this_cpu_read(printk_pending)) {
+                __this_cpu_write(printk_pending, 0);
                 wake_up_interruptible(&log_wait);
         }
 }
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index ccdc04c47981..aeebf772d6a2 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -367,8 +367,8 @@ void rcu_irq_exit(void)
         WARN_ON_ONCE(rdtp->dynticks & 0x1);
 
         /* If the interrupt queued a callback, get out of dyntick mode. */
-        if (__get_cpu_var(rcu_sched_data).nxtlist ||
-            __get_cpu_var(rcu_bh_data).nxtlist)
+        if (__this_cpu_read(rcu_sched_data.nxtlist) ||
+            __this_cpu_read(rcu_bh_data.nxtlist))
                 set_need_resched();
 }
 
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 18f4be0d5fe0..d0a0dda52c1a 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -70,7 +70,7 @@ char *softirq_to_name[NR_SOFTIRQS] = {
 static void wakeup_softirqd(void)
 {
         /* Interrupts are disabled: no need to stop preemption */
-        struct task_struct *tsk = __get_cpu_var(ksoftirqd);
+        struct task_struct *tsk = __this_cpu_read(ksoftirqd);
 
         if (tsk && tsk->state != TASK_RUNNING)
                 wake_up_process(tsk);
@@ -388,8 +388,8 @@ void __tasklet_schedule(struct tasklet_struct *t)
 
         local_irq_save(flags);
         t->next = NULL;
-        *__get_cpu_var(tasklet_vec).tail = t;
-        __get_cpu_var(tasklet_vec).tail = &(t->next);
+        *__this_cpu_read(tasklet_vec.tail) = t;
+        __this_cpu_write(tasklet_vec.tail, &(t->next));
         raise_softirq_irqoff(TASKLET_SOFTIRQ);
         local_irq_restore(flags);
 }
@@ -402,8 +402,8 @@ void __tasklet_hi_schedule(struct tasklet_struct *t)
 
         local_irq_save(flags);
         t->next = NULL;
-        *__get_cpu_var(tasklet_hi_vec).tail = t;
-        __get_cpu_var(tasklet_hi_vec).tail = &(t->next);
+        *__this_cpu_read(tasklet_hi_vec.tail) = t;
+        __this_cpu_write(tasklet_hi_vec.tail,  &(t->next));
         raise_softirq_irqoff(HI_SOFTIRQ);
         local_irq_restore(flags);
 }
@@ -414,8 +414,8 @@ void __tasklet_hi_schedule_first(struct tasklet_struct *t)
 {
         BUG_ON(!irqs_disabled());
 
-        t->next = __get_cpu_var(tasklet_hi_vec).head;
-        __get_cpu_var(tasklet_hi_vec).head = t;
+        t->next = __this_cpu_read(tasklet_hi_vec.head);
+        __this_cpu_write(tasklet_hi_vec.head, t);
         __raise_softirq_irqoff(HI_SOFTIRQ);
 }
 
@@ -426,9 +426,9 @@ static void tasklet_action(struct softirq_action *a)
         struct tasklet_struct *list;
 
         local_irq_disable();
-        list = __get_cpu_var(tasklet_vec).head;
-        __get_cpu_var(tasklet_vec).head = NULL;
-        __get_cpu_var(tasklet_vec).tail = &__get_cpu_var(tasklet_vec).head;
+        list = __this_cpu_read(tasklet_vec.head);
+        __this_cpu_write(tasklet_vec.head, NULL);
+        __this_cpu_write(tasklet_vec.tail, &__get_cpu_var(tasklet_vec).head);
         local_irq_enable();
 
         while (list) {
@@ -449,8 +449,8 @@ static void tasklet_action(struct softirq_action *a)
 
                 local_irq_disable();
                 t->next = NULL;
-                *__get_cpu_var(tasklet_vec).tail = t;
-                __get_cpu_var(tasklet_vec).tail = &(t->next);
+                *__this_cpu_read(tasklet_vec.tail) = t;
+                __this_cpu_write(tasklet_vec.tail, &(t->next));
                 __raise_softirq_irqoff(TASKLET_SOFTIRQ);
                 local_irq_enable();
         }
@@ -461,9 +461,9 @@ static void tasklet_hi_action(struct softirq_action *a)
         struct tasklet_struct *list;
 
         local_irq_disable();
-        list = __get_cpu_var(tasklet_hi_vec).head;
-        __get_cpu_var(tasklet_hi_vec).head = NULL;
-        __get_cpu_var(tasklet_hi_vec).tail = &__get_cpu_var(tasklet_hi_vec).head;
+        list = __this_cpu_read(tasklet_hi_vec.head);
+        __this_cpu_write(tasklet_hi_vec.head, NULL);
+        __this_cpu_write(tasklet_hi_vec.tail, &__get_cpu_var(tasklet_hi_vec).head);
         local_irq_enable();
 
         while (list) {
@@ -484,8 +484,8 @@ static void tasklet_hi_action(struct softirq_action *a)
 
                 local_irq_disable();
                 t->next = NULL;
-                *__get_cpu_var(tasklet_hi_vec).tail = t;
-                __get_cpu_var(tasklet_hi_vec).tail = &(t->next);
+                *__this_cpu_read(tasklet_hi_vec.tail) = t;
+                __this_cpu_write(tasklet_hi_vec.tail, &(t->next));
                 __raise_softirq_irqoff(HI_SOFTIRQ);
                 local_irq_enable();
         }
@@ -802,16 +802,16 @@ static void takeover_tasklets(unsigned int cpu)
 
         /* Find end, append list for that CPU. */
         if (&per_cpu(tasklet_vec, cpu).head != per_cpu(tasklet_vec, cpu).tail) {
-                *(__get_cpu_var(tasklet_vec).tail) = per_cpu(tasklet_vec, cpu).head;
-                __get_cpu_var(tasklet_vec).tail = per_cpu(tasklet_vec, cpu).tail;
+                *__this_cpu_read(tasklet_vec.tail) = per_cpu(tasklet_vec, cpu).head;
+                this_cpu_write(tasklet_vec.tail, per_cpu(tasklet_vec, cpu).tail);
                 per_cpu(tasklet_vec, cpu).head = NULL;
                 per_cpu(tasklet_vec, cpu).tail = &per_cpu(tasklet_vec, cpu).head;
         }
         raise_softirq_irqoff(TASKLET_SOFTIRQ);
 
         if (&per_cpu(tasklet_hi_vec, cpu).head != per_cpu(tasklet_hi_vec, cpu).tail) {
-                *__get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).head;
-                __get_cpu_var(tasklet_hi_vec).tail = per_cpu(tasklet_hi_vec, cpu).tail;
+                *__this_cpu_read(tasklet_hi_vec.tail) = per_cpu(tasklet_hi_vec, cpu).head;
+                __this_cpu_write(tasklet_hi_vec.tail, per_cpu(tasklet_hi_vec, cpu).tail);
                 per_cpu(tasklet_hi_vec, cpu).head = NULL;
                 per_cpu(tasklet_hi_vec, cpu).tail = &per_cpu(tasklet_hi_vec, cpu).head;
         }
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index b6b898d2eeef..051bc80a0c43 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -49,7 +49,7 @@ struct tick_device *tick_get_device(int cpu)
  */
 int tick_is_oneshot_available(void)
 {
-        struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+        struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 
         return dev && (dev->features & CLOCK_EVT_FEAT_ONESHOT);
 }
diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c
index aada0e52680a..5cbc101f908b 100644
--- a/kernel/time/tick-oneshot.c
+++ b/kernel/time/tick-oneshot.c
@@ -95,7 +95,7 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
  */
 int tick_program_event(ktime_t expires, int force)
 {
-        struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+        struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
 
         return tick_dev_program_event(dev, expires, force);
 }
@@ -167,7 +167,7 @@ int tick_oneshot_mode_active(void)
         int ret;
 
         local_irq_save(flags);
-        ret = __get_cpu_var(tick_cpu_device).mode == TICKDEV_MODE_ONESHOT;
+        ret = __this_cpu_read(tick_cpu_device.mode) == TICKDEV_MODE_ONESHOT;
         local_irq_restore(flags);
 
         return ret;
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 6e3c41a4024c..8037a86106ed 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;
 }