linux/kernel/smpboot.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Common SMP CPU bringup/teardown functions
 */
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/smp.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/export.h>
#include <linux/percpu.h>
#include <linux/kthread.h>
#include <linux/smpboot.h>

#include "smpboot.h"

#ifdef CONFIG_SMP

#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
/*
 * For the hotplug case we keep the task structs around and reuse
 * them.
 */
static DEFINE_PER_CPU(struct task_struct *, idle_threads);

struct task_struct *idle_thread_get(unsigned int cpu)
{ … }

void __init idle_thread_set_boot_cpu(void)
{ … }

/**
 * idle_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 __always_inline void idle_init(unsigned int cpu)
{ … }

/**
 * idle_threads_init - Initialize idle threads for all cpus
 */
void __init idle_threads_init(void)
{ … }
#endif

#endif /* #ifdef CONFIG_SMP */

static LIST_HEAD(hotplug_threads);
static DEFINE_MUTEX(smpboot_threads_lock);

struct smpboot_thread_data { … };

enum { … };

/**
 * smpboot_thread_fn - percpu hotplug thread loop function
 * @data:	thread data pointer
 *
 * Checks for thread stop and park conditions. Calls the necessary
 * setup, cleanup, park and unpark functions for the registered
 * thread.
 *
 * Returns 1 when the thread should exit, 0 otherwise.
 */
static int smpboot_thread_fn(void *data)
{ … }

static int
__smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
{ … }

int smpboot_create_threads(unsigned int cpu)
{ … }

static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
{ … }

int smpboot_unpark_threads(unsigned int cpu)
{ … }

static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
{ … }

int smpboot_park_threads(unsigned int cpu)
{ … }

static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
{ … }

/**
 * smpboot_register_percpu_thread - Register a per_cpu thread related
 * 					    to hotplug
 * @plug_thread:	Hotplug thread descriptor
 *
 * Creates and starts the threads on all online cpus.
 */
int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * smpboot_unregister_percpu_thread - Unregister a per_cpu thread related to hotplug
 * @plug_thread:	Hotplug thread descriptor
 *
 * Stops all threads on all possible cpus.
 */
void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread)
{ … }
EXPORT_SYMBOL_GPL(…);