87 lines
2.3 KiB
C
87 lines
2.3 KiB
C
/*
|
|
* Spin and read/write lock operations.
|
|
*
|
|
* Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
|
|
* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
|
|
* Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
|
|
* Rework to support virtual processors
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/export.h>
|
|
#include <linux/stringify.h>
|
|
#include <linux/smp.h>
|
|
|
|
/* waiting for a spinlock... */
|
|
#if defined(CONFIG_PPC_SPLPAR)
|
|
#include <asm/hvcall.h>
|
|
#include <asm/smp.h>
|
|
|
|
void __spin_yield(arch_spinlock_t *lock)
|
|
{
|
|
unsigned int lock_value, holder_cpu, yield_count;
|
|
|
|
lock_value = lock->slock;
|
|
if (lock_value == 0)
|
|
return;
|
|
holder_cpu = lock_value & 0xffff;
|
|
BUG_ON(holder_cpu >= NR_CPUS);
|
|
yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
|
|
if ((yield_count & 1) == 0)
|
|
return; /* virtual cpu is currently running */
|
|
rmb();
|
|
if (lock->slock != lock_value)
|
|
return; /* something has changed */
|
|
plpar_hcall_norets(H_CONFER,
|
|
get_hard_smp_processor_id(holder_cpu), yield_count);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__spin_yield);
|
|
|
|
/*
|
|
* Waiting for a read lock or a write lock on a rwlock...
|
|
* This turns out to be the same for read and write locks, since
|
|
* we only know the holder if it is write-locked.
|
|
*/
|
|
void __rw_yield(arch_rwlock_t *rw)
|
|
{
|
|
int lock_value;
|
|
unsigned int holder_cpu, yield_count;
|
|
|
|
lock_value = rw->lock;
|
|
if (lock_value >= 0)
|
|
return; /* no write lock at present */
|
|
holder_cpu = lock_value & 0xffff;
|
|
BUG_ON(holder_cpu >= NR_CPUS);
|
|
yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
|
|
if ((yield_count & 1) == 0)
|
|
return; /* virtual cpu is currently running */
|
|
rmb();
|
|
if (rw->lock != lock_value)
|
|
return; /* something has changed */
|
|
plpar_hcall_norets(H_CONFER,
|
|
get_hard_smp_processor_id(holder_cpu), yield_count);
|
|
}
|
|
#endif
|
|
|
|
void arch_spin_unlock_wait(arch_spinlock_t *lock)
|
|
{
|
|
smp_mb();
|
|
|
|
while (lock->slock) {
|
|
HMT_low();
|
|
if (SHARED_PROCESSOR)
|
|
__spin_yield(lock);
|
|
}
|
|
HMT_medium();
|
|
|
|
smp_mb();
|
|
}
|
|
|
|
EXPORT_SYMBOL(arch_spin_unlock_wait);
|