2874c5fd28
Based on 1 normalized pattern(s): 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 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 __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
|