stop_machine: Provide stop_machine_cpuslocked()

 * @fn() runs.

 *

 * This can be thought of as a very heavy write lock, equivalent to

 * grabbing every spinlock in the kernel. */

 * grabbing every spinlock in the kernel.

 *

 * Protects against CPU hotplug.

 */

int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);

/**

 * stop_machine_cpuslocked: freeze the machine on all CPUs and run this function

 * @fn: the function to run

 * @data: the data ptr for the @fn()

 * @cpus: the cpus to run the @fn() on (NULL = any online cpu)

 *

 * Same as above. Must be called from with in a cpus_read_lock() protected

 * region. Avoids nested calls to cpus_read_lock().

 */

int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);

int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,

				   const struct cpumask *cpus);

#else	/* CONFIG_SMP || CONFIG_HOTPLUG_CPU */

static inline int stop_machine(cpu_stop_fn_t fn, void *data,

static inline int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,

					  const struct cpumask *cpus)

{

	unsigned long flags;

	return ret;

}

static inline int stop_machine(cpu_stop_fn_t fn, void *data,

			       const struct cpumask *cpus)

{

	return stop_machine_cpuslocked(fn, data, cpus);

}

static inline int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,

						 const struct cpumask *cpus)

{

}

early_initcall(cpu_stop_init);

static int __stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus)

int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data,

			    const struct cpumask *cpus)

{

	struct multi_stop_data msdata = {

		.fn = fn,

		.active_cpus = cpus,

	};

	lockdep_assert_cpus_held();

	if (!stop_machine_initialized) {

		/*

		 * Handle the case where stop_machine() is called

	int ret;

	/* No CPUs can come up or down during this. */

	get_online_cpus();

	ret = __stop_machine(fn, data, cpus);

	put_online_cpus();

	cpus_read_lock();

	ret = stop_machine_cpuslocked(fn, data, cpus);

	cpus_read_unlock();

	return ret;

}

EXPORT_SYMBOL_GPL(stop_machine);