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https://github.com/edk2-porting/linux-next.git
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59b6978745
This patch introduces a new function that checks the running status of a cpu in a hypervisor. This status is not virtualized, so the check is only correct if running in an LPAR. On acquiring a spinlock, if the cpu holding the lock is scheduled by the hypervisor, we do a busy wait on the lock. If it is not scheduled, we yield over to that cpu. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
234 lines
4.7 KiB
C
234 lines
4.7 KiB
C
/*
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* arch/s390/lib/spinlock.c
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* Out of line spinlock code.
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*
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* Copyright (C) IBM Corp. 2004, 2006
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
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*/
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/init.h>
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#include <asm/io.h>
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int spin_retry = 1000;
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/**
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* spin_retry= parameter
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*/
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static int __init spin_retry_setup(char *str)
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{
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spin_retry = simple_strtoul(str, &str, 0);
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return 1;
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}
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__setup("spin_retry=", spin_retry_setup);
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static inline void _raw_yield(void)
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{
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if (MACHINE_HAS_DIAG44)
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asm volatile("diag 0,0,0x44");
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}
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static inline void _raw_yield_cpu(int cpu)
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{
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if (MACHINE_HAS_DIAG9C)
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asm volatile("diag %0,0,0x9c"
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: : "d" (cpu_logical_map(cpu)));
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else
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_raw_yield();
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}
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void arch_spin_lock_wait(arch_spinlock_t *lp)
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{
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int count = spin_retry;
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unsigned int cpu = ~smp_processor_id();
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unsigned int owner;
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while (1) {
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owner = lp->owner_cpu;
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if (!owner || smp_vcpu_scheduled(~owner)) {
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for (count = spin_retry; count > 0; count--) {
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if (arch_spin_is_locked(lp))
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continue;
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if (_raw_compare_and_swap(&lp->owner_cpu, 0,
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cpu) == 0)
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return;
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}
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if (MACHINE_IS_LPAR)
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continue;
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}
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owner = lp->owner_cpu;
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if (owner)
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_raw_yield_cpu(~owner);
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if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
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return;
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}
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}
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EXPORT_SYMBOL(arch_spin_lock_wait);
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void arch_spin_lock_wait_flags(arch_spinlock_t *lp, unsigned long flags)
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{
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int count = spin_retry;
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unsigned int cpu = ~smp_processor_id();
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unsigned int owner;
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local_irq_restore(flags);
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while (1) {
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owner = lp->owner_cpu;
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if (!owner || smp_vcpu_scheduled(~owner)) {
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for (count = spin_retry; count > 0; count--) {
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if (arch_spin_is_locked(lp))
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continue;
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local_irq_disable();
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if (_raw_compare_and_swap(&lp->owner_cpu, 0,
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cpu) == 0)
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return;
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local_irq_restore(flags);
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}
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if (MACHINE_IS_LPAR)
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continue;
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}
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owner = lp->owner_cpu;
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if (owner)
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_raw_yield_cpu(~owner);
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local_irq_disable();
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if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
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return;
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local_irq_restore(flags);
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}
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}
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EXPORT_SYMBOL(arch_spin_lock_wait_flags);
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int arch_spin_trylock_retry(arch_spinlock_t *lp)
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{
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unsigned int cpu = ~smp_processor_id();
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int count;
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for (count = spin_retry; count > 0; count--) {
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if (arch_spin_is_locked(lp))
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continue;
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if (_raw_compare_and_swap(&lp->owner_cpu, 0, cpu) == 0)
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return 1;
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}
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return 0;
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}
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EXPORT_SYMBOL(arch_spin_trylock_retry);
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void arch_spin_relax(arch_spinlock_t *lock)
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{
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unsigned int cpu = lock->owner_cpu;
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if (cpu != 0) {
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if (MACHINE_IS_VM || MACHINE_IS_KVM ||
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!smp_vcpu_scheduled(~cpu))
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_raw_yield_cpu(~cpu);
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}
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}
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EXPORT_SYMBOL(arch_spin_relax);
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void _raw_read_lock_wait(arch_rwlock_t *rw)
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{
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unsigned int old;
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int count = spin_retry;
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while (1) {
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if (count-- <= 0) {
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_raw_yield();
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count = spin_retry;
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}
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if (!arch_read_can_lock(rw))
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continue;
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old = rw->lock & 0x7fffffffU;
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if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
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return;
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}
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}
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EXPORT_SYMBOL(_raw_read_lock_wait);
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void _raw_read_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
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{
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unsigned int old;
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int count = spin_retry;
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local_irq_restore(flags);
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while (1) {
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if (count-- <= 0) {
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_raw_yield();
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count = spin_retry;
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}
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if (!arch_read_can_lock(rw))
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continue;
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old = rw->lock & 0x7fffffffU;
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local_irq_disable();
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if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
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return;
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}
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}
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EXPORT_SYMBOL(_raw_read_lock_wait_flags);
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int _raw_read_trylock_retry(arch_rwlock_t *rw)
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{
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unsigned int old;
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int count = spin_retry;
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while (count-- > 0) {
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if (!arch_read_can_lock(rw))
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continue;
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old = rw->lock & 0x7fffffffU;
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if (_raw_compare_and_swap(&rw->lock, old, old + 1) == old)
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return 1;
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}
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return 0;
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}
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EXPORT_SYMBOL(_raw_read_trylock_retry);
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void _raw_write_lock_wait(arch_rwlock_t *rw)
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{
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int count = spin_retry;
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while (1) {
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if (count-- <= 0) {
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_raw_yield();
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count = spin_retry;
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}
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if (!arch_write_can_lock(rw))
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continue;
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if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
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return;
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}
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}
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EXPORT_SYMBOL(_raw_write_lock_wait);
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void _raw_write_lock_wait_flags(arch_rwlock_t *rw, unsigned long flags)
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{
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int count = spin_retry;
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local_irq_restore(flags);
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while (1) {
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if (count-- <= 0) {
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_raw_yield();
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count = spin_retry;
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}
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if (!arch_write_can_lock(rw))
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continue;
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local_irq_disable();
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if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
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return;
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}
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}
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EXPORT_SYMBOL(_raw_write_lock_wait_flags);
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int _raw_write_trylock_retry(arch_rwlock_t *rw)
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{
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int count = spin_retry;
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while (count-- > 0) {
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if (!arch_write_can_lock(rw))
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continue;
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if (_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)
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return 1;
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}
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return 0;
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}
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EXPORT_SYMBOL(_raw_write_trylock_retry);
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