66 lines
1.8 KiB
C
66 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* 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
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/export.h>
|
|
#include <linux/smp.h>
|
|
|
|
/* waiting for a spinlock... */
|
|
#if defined(CONFIG_PPC_SPLPAR)
|
|
#include <asm/hvcall.h>
|
|
#include <asm/smp.h>
|
|
|
|
void splpar_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(splpar_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 splpar_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
|