273 lines
6.2 KiB
C
273 lines
6.2 KiB
C
#ifndef __ASM_SPINLOCK_H
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#define __ASM_SPINLOCK_H
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#ifdef __KERNEL__
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/*
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* Simple spin lock operations.
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*
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* Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
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* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
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* Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
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* Rework to support virtual processors
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*
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* Type of int is used as a full 64b word is not necessary.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* (the type definitions are in asm/spinlock_types.h)
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*/
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#ifdef CONFIG_PPC64
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#include <asm/paca.h>
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#include <asm/hvcall.h>
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#include <asm/iseries/hv_call.h>
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#endif
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#include <asm/asm-compat.h>
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#include <asm/synch.h>
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#define __raw_spin_is_locked(x) ((x)->slock != 0)
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#ifdef CONFIG_PPC64
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/* use 0x800000yy when locked, where yy == CPU number */
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#define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token))
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#else
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#define LOCK_TOKEN 1
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#endif
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/*
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* This returns the old value in the lock, so we succeeded
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* in getting the lock if the return value is 0.
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*/
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static __inline__ unsigned long __spin_trylock(raw_spinlock_t *lock)
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{
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unsigned long tmp, token;
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token = LOCK_TOKEN;
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__asm__ __volatile__(
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"1: lwarx %0,0,%2\n\
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cmpwi 0,%0,0\n\
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bne- 2f\n\
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stwcx. %1,0,%2\n\
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bne- 1b\n\
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isync\n\
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2:" : "=&r" (tmp)
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: "r" (token), "r" (&lock->slock)
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: "cr0", "memory");
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return tmp;
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}
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static int __inline__ __raw_spin_trylock(raw_spinlock_t *lock)
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{
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return __spin_trylock(lock) == 0;
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}
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/*
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* On a system with shared processors (that is, where a physical
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* processor is multiplexed between several virtual processors),
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* there is no point spinning on a lock if the holder of the lock
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* isn't currently scheduled on a physical processor. Instead
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* we detect this situation and ask the hypervisor to give the
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* rest of our timeslice to the lock holder.
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*
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* So that we can tell which virtual processor is holding a lock,
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* we put 0x80000000 | smp_processor_id() in the lock when it is
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* held. Conveniently, we have a word in the paca that holds this
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* value.
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*/
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#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
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/* We only yield to the hypervisor if we are in shared processor mode */
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#define SHARED_PROCESSOR (get_lppaca()->shared_proc)
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extern void __spin_yield(raw_spinlock_t *lock);
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extern void __rw_yield(raw_rwlock_t *lock);
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#else /* SPLPAR || ISERIES */
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#define __spin_yield(x) barrier()
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#define __rw_yield(x) barrier()
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#define SHARED_PROCESSOR 0
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#endif
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static void __inline__ __raw_spin_lock(raw_spinlock_t *lock)
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{
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while (1) {
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if (likely(__spin_trylock(lock) == 0))
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break;
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do {
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HMT_low();
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if (SHARED_PROCESSOR)
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__spin_yield(lock);
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} while (unlikely(lock->slock != 0));
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HMT_medium();
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}
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}
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static void __inline__ __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
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{
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unsigned long flags_dis;
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while (1) {
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if (likely(__spin_trylock(lock) == 0))
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break;
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local_save_flags(flags_dis);
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local_irq_restore(flags);
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do {
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HMT_low();
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if (SHARED_PROCESSOR)
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__spin_yield(lock);
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} while (unlikely(lock->slock != 0));
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HMT_medium();
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local_irq_restore(flags_dis);
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}
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}
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static __inline__ void __raw_spin_unlock(raw_spinlock_t *lock)
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{
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__asm__ __volatile__("# __raw_spin_unlock\n\t"
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LWSYNC_ON_SMP: : :"memory");
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lock->slock = 0;
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}
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#ifdef CONFIG_PPC64
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extern void __raw_spin_unlock_wait(raw_spinlock_t *lock);
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#else
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#define __raw_spin_unlock_wait(lock) \
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do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
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#endif
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/*
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* Read-write spinlocks, allowing multiple readers
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* but only one writer.
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*
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* NOTE! it is quite common to have readers in interrupts
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* but no interrupt writers. For those circumstances we
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* can "mix" irq-safe locks - any writer needs to get a
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* irq-safe write-lock, but readers can get non-irqsafe
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* read-locks.
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*/
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#define __raw_read_can_lock(rw) ((rw)->lock >= 0)
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#define __raw_write_can_lock(rw) (!(rw)->lock)
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#ifdef CONFIG_PPC64
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#define __DO_SIGN_EXTEND "extsw %0,%0\n"
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#define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */
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#else
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#define __DO_SIGN_EXTEND
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#define WRLOCK_TOKEN (-1)
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#endif
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/*
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* This returns the old value in the lock + 1,
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* so we got a read lock if the return value is > 0.
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*/
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static long __inline__ __read_trylock(raw_rwlock_t *rw)
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{
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long tmp;
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__asm__ __volatile__(
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"1: lwarx %0,0,%1\n"
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__DO_SIGN_EXTEND
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" addic. %0,%0,1\n\
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ble- 2f\n"
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PPC405_ERR77(0,%1)
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" stwcx. %0,0,%1\n\
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bne- 1b\n\
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isync\n\
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2:" : "=&r" (tmp)
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: "r" (&rw->lock)
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: "cr0", "xer", "memory");
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return tmp;
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}
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/*
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* This returns the old value in the lock,
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* so we got the write lock if the return value is 0.
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*/
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static __inline__ long __write_trylock(raw_rwlock_t *rw)
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{
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long tmp, token;
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token = WRLOCK_TOKEN;
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__asm__ __volatile__(
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"1: lwarx %0,0,%2\n\
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cmpwi 0,%0,0\n\
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bne- 2f\n"
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PPC405_ERR77(0,%1)
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" stwcx. %1,0,%2\n\
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bne- 1b\n\
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isync\n\
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2:" : "=&r" (tmp)
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: "r" (token), "r" (&rw->lock)
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: "cr0", "memory");
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return tmp;
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}
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static void __inline__ __raw_read_lock(raw_rwlock_t *rw)
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{
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while (1) {
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if (likely(__read_trylock(rw) > 0))
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break;
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do {
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HMT_low();
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if (SHARED_PROCESSOR)
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__rw_yield(rw);
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} while (unlikely(rw->lock < 0));
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HMT_medium();
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}
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}
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static void __inline__ __raw_write_lock(raw_rwlock_t *rw)
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{
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while (1) {
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if (likely(__write_trylock(rw) == 0))
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break;
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do {
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HMT_low();
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if (SHARED_PROCESSOR)
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__rw_yield(rw);
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} while (unlikely(rw->lock != 0));
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HMT_medium();
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}
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}
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static int __inline__ __raw_read_trylock(raw_rwlock_t *rw)
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{
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return __read_trylock(rw) > 0;
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}
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static int __inline__ __raw_write_trylock(raw_rwlock_t *rw)
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{
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return __write_trylock(rw) == 0;
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}
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static void __inline__ __raw_read_unlock(raw_rwlock_t *rw)
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{
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long tmp;
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__asm__ __volatile__(
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"# read_unlock\n\t"
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LWSYNC_ON_SMP
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"1: lwarx %0,0,%1\n\
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addic %0,%0,-1\n"
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PPC405_ERR77(0,%1)
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" stwcx. %0,0,%1\n\
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bne- 1b"
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: "=&r"(tmp)
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: "r"(&rw->lock)
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: "cr0", "memory");
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}
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static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
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{
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__asm__ __volatile__("# write_unlock\n\t"
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LWSYNC_ON_SMP: : :"memory");
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rw->lock = 0;
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}
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#endif /* __KERNEL__ */
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#endif /* __ASM_SPINLOCK_H */
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