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authorChristoph Lameter <cl@linux.com>2010-12-08 16:22:55 +0100
committerTejun Heo <tj@kernel.org>2010-12-17 15:07:19 +0100
commit909ea96468096b07fbb41aaf69be060d92bd9271 (patch)
treea7e015edd96b5f674874fe78cdd889769e130a2a /kernel/softirq.c
parent780f36d8b3fa9572f731d4fb85067b2e45e6f993 (diff)
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>
Diffstat (limited to 'kernel/softirq.c')
-rw-r--r--kernel/softirq.c42
1 files changed, 21 insertions, 21 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 18f4be0d5fe..d0a0dda52c1 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;
}