317 lines
7.0 KiB
C
317 lines
7.0 KiB
C
/*
|
|
* Common SMP CPU bringup/teardown functions
|
|
*/
|
|
#include <linux/cpu.h>
|
|
#include <linux/err.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/init.h>
|
|
#include <linux/list.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/sched.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)
|
|
{
|
|
struct task_struct *tsk = per_cpu(idle_threads, cpu);
|
|
|
|
if (!tsk)
|
|
return ERR_PTR(-ENOMEM);
|
|
init_idle(tsk, cpu);
|
|
return tsk;
|
|
}
|
|
|
|
void __init idle_thread_set_boot_cpu(void)
|
|
{
|
|
per_cpu(idle_threads, smp_processor_id()) = current;
|
|
}
|
|
|
|
/**
|
|
* 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 inline void idle_init(unsigned int cpu)
|
|
{
|
|
struct task_struct *tsk = per_cpu(idle_threads, cpu);
|
|
|
|
if (!tsk) {
|
|
tsk = fork_idle(cpu);
|
|
if (IS_ERR(tsk))
|
|
pr_err("SMP: fork_idle() failed for CPU %u\n", cpu);
|
|
else
|
|
per_cpu(idle_threads, cpu) = tsk;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* idle_threads_init - Initialize idle threads for all cpus
|
|
*/
|
|
void __init idle_threads_init(void)
|
|
{
|
|
unsigned int cpu, boot_cpu;
|
|
|
|
boot_cpu = smp_processor_id();
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
if (cpu != boot_cpu)
|
|
idle_init(cpu);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
#endif /* #ifdef CONFIG_SMP */
|
|
|
|
static LIST_HEAD(hotplug_threads);
|
|
static DEFINE_MUTEX(smpboot_threads_lock);
|
|
|
|
struct smpboot_thread_data {
|
|
unsigned int cpu;
|
|
unsigned int status;
|
|
struct smp_hotplug_thread *ht;
|
|
};
|
|
|
|
enum {
|
|
HP_THREAD_NONE = 0,
|
|
HP_THREAD_ACTIVE,
|
|
HP_THREAD_PARKED,
|
|
};
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
struct smpboot_thread_data *td = data;
|
|
struct smp_hotplug_thread *ht = td->ht;
|
|
|
|
while (1) {
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
preempt_disable();
|
|
if (kthread_should_stop()) {
|
|
__set_current_state(TASK_RUNNING);
|
|
preempt_enable();
|
|
if (ht->cleanup)
|
|
ht->cleanup(td->cpu, cpu_online(td->cpu));
|
|
kfree(td);
|
|
return 0;
|
|
}
|
|
|
|
if (kthread_should_park()) {
|
|
__set_current_state(TASK_RUNNING);
|
|
preempt_enable();
|
|
if (ht->park && td->status == HP_THREAD_ACTIVE) {
|
|
BUG_ON(td->cpu != smp_processor_id());
|
|
ht->park(td->cpu);
|
|
td->status = HP_THREAD_PARKED;
|
|
}
|
|
kthread_parkme();
|
|
/* We might have been woken for stop */
|
|
continue;
|
|
}
|
|
|
|
BUG_ON(td->cpu != smp_processor_id());
|
|
|
|
/* Check for state change setup */
|
|
switch (td->status) {
|
|
case HP_THREAD_NONE:
|
|
__set_current_state(TASK_RUNNING);
|
|
preempt_enable();
|
|
if (ht->setup)
|
|
ht->setup(td->cpu);
|
|
td->status = HP_THREAD_ACTIVE;
|
|
continue;
|
|
|
|
case HP_THREAD_PARKED:
|
|
__set_current_state(TASK_RUNNING);
|
|
preempt_enable();
|
|
if (ht->unpark)
|
|
ht->unpark(td->cpu);
|
|
td->status = HP_THREAD_ACTIVE;
|
|
continue;
|
|
}
|
|
|
|
if (!ht->thread_should_run(td->cpu)) {
|
|
preempt_enable_no_resched();
|
|
schedule();
|
|
} else {
|
|
__set_current_state(TASK_RUNNING);
|
|
preempt_enable();
|
|
ht->thread_fn(td->cpu);
|
|
}
|
|
}
|
|
}
|
|
|
|
static int
|
|
__smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
|
|
{
|
|
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
|
|
struct smpboot_thread_data *td;
|
|
|
|
if (tsk)
|
|
return 0;
|
|
|
|
td = kzalloc_node(sizeof(*td), GFP_KERNEL, cpu_to_node(cpu));
|
|
if (!td)
|
|
return -ENOMEM;
|
|
td->cpu = cpu;
|
|
td->ht = ht;
|
|
|
|
tsk = kthread_create_on_cpu(smpboot_thread_fn, td, cpu,
|
|
ht->thread_comm);
|
|
if (IS_ERR(tsk)) {
|
|
kfree(td);
|
|
return PTR_ERR(tsk);
|
|
}
|
|
get_task_struct(tsk);
|
|
*per_cpu_ptr(ht->store, cpu) = tsk;
|
|
if (ht->create) {
|
|
/*
|
|
* Make sure that the task has actually scheduled out
|
|
* into park position, before calling the create
|
|
* callback. At least the migration thread callback
|
|
* requires that the task is off the runqueue.
|
|
*/
|
|
if (!wait_task_inactive(tsk, TASK_PARKED))
|
|
WARN_ON(1);
|
|
else
|
|
ht->create(cpu);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int smpboot_create_threads(unsigned int cpu)
|
|
{
|
|
struct smp_hotplug_thread *cur;
|
|
int ret = 0;
|
|
|
|
mutex_lock(&smpboot_threads_lock);
|
|
list_for_each_entry(cur, &hotplug_threads, list) {
|
|
ret = __smpboot_create_thread(cur, cpu);
|
|
if (ret)
|
|
break;
|
|
}
|
|
mutex_unlock(&smpboot_threads_lock);
|
|
return ret;
|
|
}
|
|
|
|
static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
|
|
{
|
|
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
|
|
|
|
if (ht->pre_unpark)
|
|
ht->pre_unpark(cpu);
|
|
kthread_unpark(tsk);
|
|
}
|
|
|
|
void smpboot_unpark_threads(unsigned int cpu)
|
|
{
|
|
struct smp_hotplug_thread *cur;
|
|
|
|
mutex_lock(&smpboot_threads_lock);
|
|
list_for_each_entry(cur, &hotplug_threads, list)
|
|
smpboot_unpark_thread(cur, cpu);
|
|
mutex_unlock(&smpboot_threads_lock);
|
|
}
|
|
|
|
static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
|
|
{
|
|
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
|
|
|
|
if (tsk && !ht->selfparking)
|
|
kthread_park(tsk);
|
|
}
|
|
|
|
void smpboot_park_threads(unsigned int cpu)
|
|
{
|
|
struct smp_hotplug_thread *cur;
|
|
|
|
mutex_lock(&smpboot_threads_lock);
|
|
list_for_each_entry_reverse(cur, &hotplug_threads, list)
|
|
smpboot_park_thread(cur, cpu);
|
|
mutex_unlock(&smpboot_threads_lock);
|
|
}
|
|
|
|
static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
|
|
{
|
|
unsigned int cpu;
|
|
|
|
/* We need to destroy also the parked threads of offline cpus */
|
|
for_each_possible_cpu(cpu) {
|
|
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
|
|
|
|
if (tsk) {
|
|
kthread_stop(tsk);
|
|
put_task_struct(tsk);
|
|
*per_cpu_ptr(ht->store, cpu) = NULL;
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
unsigned int cpu;
|
|
int ret = 0;
|
|
|
|
get_online_cpus();
|
|
mutex_lock(&smpboot_threads_lock);
|
|
for_each_online_cpu(cpu) {
|
|
ret = __smpboot_create_thread(plug_thread, cpu);
|
|
if (ret) {
|
|
smpboot_destroy_threads(plug_thread);
|
|
goto out;
|
|
}
|
|
smpboot_unpark_thread(plug_thread, cpu);
|
|
}
|
|
list_add(&plug_thread->list, &hotplug_threads);
|
|
out:
|
|
mutex_unlock(&smpboot_threads_lock);
|
|
put_online_cpus();
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
get_online_cpus();
|
|
mutex_lock(&smpboot_threads_lock);
|
|
list_del(&plug_thread->list);
|
|
smpboot_destroy_threads(plug_thread);
|
|
mutex_unlock(&smpboot_threads_lock);
|
|
put_online_cpus();
|
|
}
|
|
EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread);
|