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: Thomas 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.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner
Родитель
860a0ffaa3
Коммит
14e568e78f
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@ -254,6 +254,8 @@ static int __ref take_cpu_down(void *_param)
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return err;
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cpu_notify(CPU_DYING | param->mod, param->hcpu);
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/* Park the stopper thread */
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kthread_park(current);
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return 0;
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}
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@ -18,7 +18,7 @@
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#include <linux/stop_machine.h>
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#include <linux/interrupt.h>
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#include <linux/kallsyms.h>
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#include <linux/smpboot.h>
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#include <linux/atomic.h>
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/*
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@ -245,20 +245,25 @@ int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg)
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return ret;
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}
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static int cpu_stopper_thread(void *data)
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static int cpu_stop_should_run(unsigned int cpu)
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{
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struct cpu_stopper *stopper = data;
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struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
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unsigned long flags;
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int run;
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spin_lock_irqsave(&stopper->lock, flags);
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run = !list_empty(&stopper->works);
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spin_unlock_irqrestore(&stopper->lock, flags);
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return run;
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}
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static void cpu_stopper_thread(unsigned int cpu)
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{
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struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
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struct cpu_stop_work *work;
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int ret;
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repeat:
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set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
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if (kthread_should_stop()) {
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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work = NULL;
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spin_lock_irq(&stopper->lock);
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if (!list_empty(&stopper->works)) {
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@ -274,8 +279,6 @@ repeat:
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struct cpu_stop_done *done = work->done;
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char ksym_buf[KSYM_NAME_LEN] __maybe_unused;
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__set_current_state(TASK_RUNNING);
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/* cpu stop callbacks are not allowed to sleep */
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preempt_disable();
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@ -291,87 +294,55 @@ repeat:
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ksym_buf), arg);
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cpu_stop_signal_done(done, true);
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} else
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schedule();
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goto repeat;
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goto repeat;
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}
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}
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extern void sched_set_stop_task(int cpu, struct task_struct *stop);
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/* manage stopper for a cpu, mostly lifted from sched migration thread mgmt */
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static int __cpuinit cpu_stop_cpu_callback(struct notifier_block *nfb,
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unsigned long action, void *hcpu)
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static void cpu_stop_create(unsigned int cpu)
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{
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unsigned int cpu = (unsigned long)hcpu;
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struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
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struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
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switch (action & ~CPU_TASKS_FROZEN) {
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case CPU_UP_PREPARE:
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BUG_ON(p || stopper->enabled || !list_empty(&stopper->works));
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p = kthread_create_on_node(cpu_stopper_thread,
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stopper,
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cpu_to_node(cpu),
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"migration/%d", cpu);
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if (IS_ERR(p))
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return notifier_from_errno(PTR_ERR(p));
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get_task_struct(p);
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kthread_bind(p, cpu);
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sched_set_stop_task(cpu, p);
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per_cpu(cpu_stopper_task, cpu) = p;
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break;
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case CPU_ONLINE:
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/* strictly unnecessary, as first user will wake it */
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wake_up_process(p);
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/* mark enabled */
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spin_lock_irq(&stopper->lock);
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stopper->enabled = true;
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spin_unlock_irq(&stopper->lock);
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break;
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#ifdef CONFIG_HOTPLUG_CPU
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case CPU_UP_CANCELED:
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case CPU_POST_DEAD:
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{
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struct cpu_stop_work *work;
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sched_set_stop_task(cpu, NULL);
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/* kill the stopper */
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kthread_stop(p);
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/* drain remaining works */
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spin_lock_irq(&stopper->lock);
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list_for_each_entry(work, &stopper->works, list)
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cpu_stop_signal_done(work->done, false);
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stopper->enabled = false;
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spin_unlock_irq(&stopper->lock);
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/* release the stopper */
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put_task_struct(p);
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per_cpu(cpu_stopper_task, cpu) = NULL;
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break;
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}
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#endif
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}
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return NOTIFY_OK;
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sched_set_stop_task(cpu, per_cpu(cpu_stopper_task, cpu));
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}
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/*
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* Give it a higher priority so that cpu stopper is available to other
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* cpu notifiers. It currently shares the same priority as sched
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* migration_notifier.
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*/
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static struct notifier_block __cpuinitdata cpu_stop_cpu_notifier = {
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.notifier_call = cpu_stop_cpu_callback,
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.priority = 10,
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static void cpu_stop_park(unsigned int cpu)
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{
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struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
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struct cpu_stop_work *work;
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unsigned long flags;
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/* drain remaining works */
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spin_lock_irqsave(&stopper->lock, flags);
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list_for_each_entry(work, &stopper->works, list)
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cpu_stop_signal_done(work->done, false);
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stopper->enabled = false;
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spin_unlock_irqrestore(&stopper->lock, flags);
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}
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static void cpu_stop_unpark(unsigned int cpu)
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{
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struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
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spin_lock_irq(&stopper->lock);
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stopper->enabled = true;
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spin_unlock_irq(&stopper->lock);
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}
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static struct smp_hotplug_thread cpu_stop_threads = {
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.store = &cpu_stopper_task,
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.thread_should_run = cpu_stop_should_run,
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.thread_fn = cpu_stopper_thread,
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.thread_comm = "migration/%u",
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.create = cpu_stop_create,
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.setup = cpu_stop_unpark,
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.park = cpu_stop_park,
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.unpark = cpu_stop_unpark,
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.selfparking = true,
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};
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static int __init cpu_stop_init(void)
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{
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void *bcpu = (void *)(long)smp_processor_id();
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unsigned int cpu;
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int err;
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for_each_possible_cpu(cpu) {
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struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
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@ -380,15 +351,8 @@ static int __init cpu_stop_init(void)
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INIT_LIST_HEAD(&stopper->works);
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}
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/* start one for the boot cpu */
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err = cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_UP_PREPARE,
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bcpu);
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BUG_ON(err != NOTIFY_OK);
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cpu_stop_cpu_callback(&cpu_stop_cpu_notifier, CPU_ONLINE, bcpu);
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register_cpu_notifier(&cpu_stop_cpu_notifier);
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BUG_ON(smpboot_register_percpu_thread(&cpu_stop_threads));
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stop_machine_initialized = true;
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return 0;
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}
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early_initcall(cpu_stop_init);
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