Commit 14e568e7 authored by Thomas Gleixner's avatar Thomas Gleixner

stop_machine: Use smpboot threads

Use the smpboot thread infrastructure. Mark the stopper thread
selfparking and park it after it has finished the take_cpu_down()
work.
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Arjan van de Veen <arjan@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Weinberger <rw@linutronix.de>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130131120741.686315164@linutronix.deSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 860a0ffa
......@@ -254,6 +254,8 @@ static int __ref take_cpu_down(void *_param)
return err;
cpu_notify(CPU_DYING | param->mod, param->hcpu);
/* Park the stopper thread */
kthread_park(current);
return 0;
}
......
......@@ -18,7 +18,7 @@
#include <linux/stop_machine.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/smpboot.h>
#include <linux/atomic.h>
/*
......@@ -245,20 +245,25 @@ int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
return ret;
}
static int cpu_stopper_thread(void *data)
static int cpu_stop_should_run(unsigned int cpu)
{
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
unsigned long flags;
int run;
spin_lock_irqsave(&stopper->lock, flags);
run = !list_empty(&stopper->works);
spin_unlock_irqrestore(&stopper->lock, flags);
return run;
}
static void cpu_stopper_thread(unsigned int cpu)
{
struct cpu_stopper *stopper = data;
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
struct cpu_stop_work *work;
int ret;
repeat:
set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
if (kthread_should_stop()) {
__set_current_state(TASK_RUNNING);
return 0;
}
work = NULL;
spin_lock_irq(&stopper->lock);
if (!list_empty(&stopper->works)) {
......@@ -274,8 +279,6 @@ repeat:
struct cpu_stop_done *done = work->done;
char ksym_buf[KSYM_NAME_LEN] __maybe_unused;
__set_current_state(TASK_RUNNING);
/* cpu stop callbacks are not allowed to sleep */
preempt_disable();
......@@ -291,87 +294,55 @@ repeat:
ksym_buf), arg);
cpu_stop_signal_done(done, true);
} else
schedule();
goto repeat;
goto repeat;
}
}
extern void sched_set_stop_task(int cpu, struct task_struct *stop);
/* manage stopper for a cpu, mostly lifted from sched migration thread mgmt */
static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
static void cpu_stop_create(unsigned int cpu)
{
sched_set_stop_task(cpu, per_cpu(cpu_stopper_task, cpu));
}
static void cpu_stop_park(unsigned int cpu)
{
unsigned int cpu = (unsigned long)hcpu;
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
struct cpu_stop_work *work;
unsigned long flags;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
BUG_ON(p || stopper->enabled || !list_empty(&stopper->works));
p = kthread_create_on_node(cpu_stopper_thread,
stopper,
cpu_to_node(cpu),
"migration/%d", cpu);
if (IS_ERR(p))
return notifier_from_errno(PTR_ERR(p));
get_task_struct(p);
kthread_bind(p, cpu);
sched_set_stop_task(cpu, p);
per_cpu(cpu_stopper_task, cpu) = p;
break;
case CPU_ONLINE:
/* strictly unnecessary, as first user will wake it */
wake_up_process(p);
/* mark enabled */
spin_lock_irq(&stopper->lock);
stopper->enabled = true;
spin_unlock_irq(&stopper->lock);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
case CPU_POST_DEAD:
{
struct cpu_stop_work *work;
sched_set_stop_task(cpu, NULL);
/* kill the stopper */
kthread_stop(p);
/* drain remaining works */
spin_lock_irq(&stopper->lock);
list_for_each_entry(work, &stopper->works, list)
cpu_stop_signal_done(work->done, false);
stopper->enabled = false;
spin_unlock_irq(&stopper->lock);
/* release the stopper */
put_task_struct(p);
per_cpu(cpu_stopper_task, cpu) = NULL;
break;
}
#endif
}
/* drain remaining works */
spin_lock_irqsave(&stopper->lock, flags);
list_for_each_entry(work, &stopper->works, list)
cpu_stop_signal_done(work->done, false);
stopper->enabled = false;
spin_unlock_irqrestore(&stopper->lock, flags);
}
return NOTIFY_OK;
static void cpu_stop_unpark(unsigned int cpu)
{
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
spin_lock_irq(&stopper->lock);
stopper->enabled = true;
spin_unlock_irq(&stopper->lock);
}
/*
* Give it a higher priority so that cpu stopper is available to other
* cpu notifiers. It currently shares the same priority as sched
* migration_notifier.
*/
static struct notifier_block __cpuinitdata cpu_stop_cpu_notifier = {
.notifier_call = cpu_stop_cpu_callback,
.priority = 10,
static struct smp_hotplug_thread cpu_stop_threads = {
.store = &cpu_stopper_task,
.thread_should_run = cpu_stop_should_run,
.thread_fn = cpu_stopper_thread,
.thread_comm = "migration/%u",
.create = cpu_stop_create,
.setup = cpu_stop_unpark,
.park = cpu_stop_park,
.unpark = cpu_stop_unpark,
.selfparking = true,
};
static int __init cpu_stop_init(void)
{
void *bcpu = (void *)(long)smp_processor_id();
unsigned int cpu;
int err;
for_each_possible_cpu(cpu) {
struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
......@@ -380,15 +351,8 @@ static int __init cpu_stop_init(void)
INIT_LIST_HEAD(&stopper->works);
}
/* start one for the boot cpu */
err = cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_UP_PREPARE,
bcpu);
BUG_ON(err != NOTIFY_OK);
cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu);
register_cpu_notifier(&cpu_stop_cpu_notifier);
BUG_ON(smpboot_register_percpu_thread(&cpu_stop_threads));
stop_machine_initialized = true;
return 0;
}
early_initcall(cpu_stop_init);
......
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