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>
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index aaac68c..95d178c 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -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 @@
return ret;
}
-static int cpu_stopper_thread(void *data)
+static int cpu_stop_should_run(unsigned int cpu)
{
- struct cpu_stopper *stopper = data;
+ 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 = &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 @@
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 @@
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)
{
- 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);
-
- 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
- }
-
- return NOTIFY_OK;
+ sched_set_stop_task(cpu, per_cpu(cpu_stopper_task, cpu));
}
-/*
- * 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_park(unsigned int cpu)
+{
+ struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
+ struct cpu_stop_work *work;
+ unsigned long flags;
+
+ /* 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);
+}
+
+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);
@@ -380,15 +351,8 @@
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);
