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/*
* drivers/power/smp.c - Functions for stopping other CPUs.
*
* Copyright 2004 Pavel Machek <pavel@suse.cz>
* Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz>
*
* This file is released under the GPLv2.
*/
#undef DEBUG
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <asm/atomic.h>
#include <asm/tlbflush.h>
static atomic_t cpu_counter, freeze;
static void smp_pause(void * data)
{
struct saved_context ctxt;
__save_processor_state(&ctxt);
printk("Sleeping in:\n");
dump_stack();
atomic_inc(&cpu_counter);
while (atomic_read(&freeze)) {
/* FIXME: restore takes place at random piece inside this.
This should probably be written in assembly, and
preserve general-purpose registers, too
What about stack? We may need to move to new stack here.
This should better be ran with interrupts disabled.
*/
cpu_relax();
barrier();
}
atomic_dec(&cpu_counter);
__restore_processor_state(&ctxt);
}
static cpumask_t oldmask;
void disable_nonboot_cpus(void)
{
printk("Freezing CPUs (at %d)", smp_processor_id());
oldmask = current->cpus_allowed;
set_cpus_allowed(current, cpumask_of_cpu(0));
current->state = TASK_INTERRUPTIBLE;
schedule_timeout(HZ);
printk("...");
BUG_ON(smp_processor_id() != 0);
/* FIXME: for this to work, all the CPUs must be running
* "idle" thread (or we deadlock). Is that guaranteed? */
atomic_set(&cpu_counter, 0);
atomic_set(&freeze, 1);
smp_call_function(smp_pause, NULL, 0, 0);
while (atomic_read(&cpu_counter) < (num_online_cpus() - 1)) {
cpu_relax();
barrier();
}
printk("ok\n");
}
void enable_nonboot_cpus(void)
{
printk("Restarting CPUs");
atomic_set(&freeze, 0);
while (atomic_read(&cpu_counter)) {
cpu_relax();
barrier();
}
printk("...");
set_cpus_allowed(current, oldmask);
schedule();
printk("ok\n");
}
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