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/*
* Out of line spinlock code.
*
* Copyright IBM Corp. 2004, 2006
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*/
#include <linux/types.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <asm/io.h>
int spin_retry = 1000;
/**
* spin_retry= parameter
*/
static int __init spin_retry_setup(char *str)
{
spin_retry = simple_strtoul(str, &str, 0);
return 1;
}
__setup("spin_retry=", spin_retry_setup);
void arch_spin_lock_wait(arch_spinlock_t *lp)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
unsigned int owner;
while (1) {
owner = lp->owner_cpu;
if (!owner || smp_vcpu_scheduled(~owner)) {
for (count = spin_retry; count > 0; count--) {
if (arch_spin_is_locked(lp))
continue;
if (_raw_compare_and_swap(&lp->owner_cpu, 0,
cpu) == 0)
return;
}
if (MACHINE_IS_LPAR)
continue;
}
owner = lp->owner_cpu;
if (owner)
smp_yield_cpu(~owner);
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
return;
}
}
EXPORT_SYMBOL(arch_spin_lock_wait);
void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
{
int count = spin_retry;
unsigned int cpu = ~smp_processor_id();
unsigned int owner;
local_irq_restore(flags);
while (1) {
owner = lp->owner_cpu;
if (!owner || smp_vcpu_scheduled(~owner)) {
for (count = spin_retry; count > 0; count--) {
if (arch_spin_is_locked(lp))
continue;
local_irq_disable();
if (_raw_compare_and_swap(&lp->owner_cpu, 0,
cpu) == 0)
return;
local_irq_restore(flags);
}
if (MACHINE_IS_LPAR)
continue;
}
owner = lp->owner_cpu;
if (owner)
smp_yield_cpu(~owner);
local_irq_disable();
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
return;
local_irq_restore(flags);
}
}
EXPORT_SYMBOL(arch_spin_lock_wait_flags);
int arch_spin_trylock_retry(arch_spinlock_t *lp)
{
unsigned int cpu = ~smp_processor_id();
int count;
for (count = spin_retry; count > 0; count--) {
if (arch_spin_is_locked(lp))
continue;
if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
return 1;
}
return 0;
}
EXPORT_SYMBOL(arch_spin_trylock_retry);
void arch_spin_relax(arch_spinlock_t *lock)
{
unsigned int cpu = lock->owner_cpu;
if (cpu != 0) {
if (MACHINE_IS_VM || MACHINE_IS_KVM ||
!smp_vcpu_scheduled(~cpu))
smp_yield_cpu(~cpu);
}
}
EXPORT_SYMBOL(arch_spin_relax);
void _raw_read_lock_wait(arch_rwlock_t *rw)
{
unsigned int old;
int count = spin_retry;
while (1) {
if (count-- <= 0) {
smp_yield();
count = spin_retry;
}
if (!arch_read_can_lock(rw))
continue;
old = rw->lock & 0x7fffffffU;
if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
return;
}
}
EXPORT_SYMBOL(_raw_read_lock_wait);
void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
{
unsigned int old;
int count = spin_retry;
local_irq_restore(flags);
while (1) {
if (count-- <= 0) {
smp_yield();
count = spin_retry;
}
if (!arch_read_can_lock(rw))
continue;
old = rw->lock & 0x7fffffffU;
local_irq_disable();
if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
return;
}
}
EXPORT_SYMBOL(_raw_read_lock_wait_flags);
int _raw_read_trylock_retry(arch_rwlock_t *rw)
{
unsigned int old;
int count = spin_retry;
while (count-- > 0) {
if (!arch_read_can_lock(rw))
continue;
old = rw->lock & 0x7fffffffU;
if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
return 1;
}
return 0;
}
EXPORT_SYMBOL(_raw_read_trylock_retry);
void _raw_write_lock_wait(arch_rwlock_t *rw)
{
int count = spin_retry;
while (1) {
if (count-- <= 0) {
smp_yield();
count = spin_retry;
}
if (!arch_write_can_lock(rw))
continue;
if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
return;
}
}
EXPORT_SYMBOL(_raw_write_lock_wait);
void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
{
int count = spin_retry;
local_irq_restore(flags);
while (1) {
if (count-- <= 0) {
smp_yield();
count = spin_retry;
}
if (!arch_write_can_lock(rw))
continue;
local_irq_disable();
if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
return;
}
}
EXPORT_SYMBOL(_raw_write_lock_wait_flags);
int _raw_write_trylock_retry(arch_rwlock_t *rw)
{
int count = spin_retry;
while (count-- > 0) {
if (!arch_write_can_lock(rw))
continue;
if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
return 1;
}
return 0;
}
EXPORT_SYMBOL(_raw_write_trylock_retry);
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