#include <linux/stop_machine.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
-
+#include <linux/smpboot.h>
#include <linux/atomic.h>
/*
spinlock_t lock;
bool enabled; /* is this stopper enabled? */
struct list_head works; /* list of pending works */
- struct task_struct *thread; /* stopper thread */
};
static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper);
+static DEFINE_PER_CPU(struct task_struct *, cpu_stopper_task);
static bool stop_machine_initialized = false;
static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
}
/* queue @work to @stopper. if offline, @work is completed immediately */
-static void cpu_stop_queue_work(struct cpu_stopper *stopper,
- struct cpu_stop_work *work)
+static void cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
{
+ struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+ struct task_struct *p = per_cpu(cpu_stopper_task, cpu);
+
unsigned long flags;
spin_lock_irqsave(&stopper->lock, flags);
if (stopper->enabled) {
list_add_tail(&work->list, &stopper->works);
- wake_up_process(stopper->thread);
+ wake_up_process(p);
} else
cpu_stop_signal_done(work->done, false);
struct cpu_stop_work work = { .fn = fn, .arg = arg, .done = &done };
cpu_stop_init_done(&done, 1);
- cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), &work);
+ cpu_stop_queue_work(cpu, &work);
wait_for_completion(&done.completion);
return done.executed ? done.ret : -ENOENT;
}
struct cpu_stop_work *work_buf)
{
*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg, };
- cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu), work_buf);
+ cpu_stop_queue_work(cpu, work_buf);
}
/* static data for stop_cpus */
*/
preempt_disable();
for_each_cpu(cpu, cpumask)
- cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu),
- &per_cpu(stop_cpus_work, cpu));
+ cpu_stop_queue_work(cpu, &per_cpu(stop_cpus_work, cpu));
preempt_enable();
}
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)) {
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();
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;
-
- switch (action & ~CPU_TASKS_FROZEN) {
- case CPU_UP_PREPARE:
- BUG_ON(stopper->thread || 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);
- stopper->thread = p;
- break;
-
- case CPU_ONLINE:
- /* strictly unnecessary, as first user will wake it */
- wake_up_process(stopper->thread);
- /* 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(stopper->thread);
- /* 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(stopper->thread);
- stopper->thread = NULL;
- break;
- }
-#endif
- }
+ struct cpu_stop_work *work;
+ unsigned long flags;
- return NOTIFY_OK;
+ /* 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);
}
-/*
- * 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 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);
+}
+
+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);
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);
projects / firefly-linux-kernel-4.4.55.git / blobdiff