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/*
* Common SMP CPU bringup/teardown functions
*/
#include <linux/err.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/percpu.h>
#include <linux/workqueue.h>
#include "smpboot.h"
#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
struct create_idle {
struct work_struct work;
struct task_struct *idle;
struct completion done;
unsigned int cpu;
};
static void __cpuinit do_fork_idle(struct work_struct *work)
{
struct create_idle *c = container_of(work, struct create_idle, work);
c->idle = fork_idle(c->cpu);
complete(&c->done);
}
static struct task_struct * __cpuinit idle_thread_create(unsigned int cpu)
{
struct create_idle c_idle = {
.cpu = cpu,
.done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
};
INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);
schedule_work(&c_idle.work);
wait_for_completion(&c_idle.done);
destroy_work_on_stack(&c_idle.work);
return c_idle.idle;
}
/*
* For the hotplug case we keep the task structs around and reuse
* them.
*/
static DEFINE_PER_CPU(struct task_struct *, idle_threads);
static inline struct task_struct *get_idle_for_cpu(unsigned int cpu)
{
struct task_struct *tsk = per_cpu(idle_threads, cpu);
if (!tsk)
return idle_thread_create(cpu);
init_idle(tsk, cpu);
return tsk;
}
struct task_struct * __cpuinit idle_thread_get(unsigned int cpu)
{
return per_cpu(idle_threads, cpu);
}
void __init idle_thread_set_boot_cpu(void)
{
per_cpu(idle_threads, smp_processor_id()) = current;
}
/**
* idle_thread_init - Initialize the idle thread for a cpu
* @cpu: The cpu for which the idle thread should be initialized
*
* Creates the thread if it does not exist.
*/
static int __cpuinit idle_thread_init(unsigned int cpu)
{
struct task_struct *idle = get_idle_for_cpu(cpu);
if (IS_ERR(idle)) {
printk(KERN_ERR "failed fork for CPU %u\n", cpu);
return PTR_ERR(idle);
}
per_cpu(idle_threads, cpu) = idle;
return 0;
}
#else
static inline int idle_thread_init(unsigned int cpu) { return 0; }
#endif
/**
* smpboot_prepare - generic smpboot preparation
*/
int __cpuinit smpboot_prepare(unsigned int cpu)
{
return idle_thread_init(cpu);
}
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