stopmachine: semaphore to mutex

static enum stopmachine_state stopmachine_state;

static unsigned int stopmachine_num_threads;

static atomic_t stopmachine_thread_ack;

static DECLARE_MUTEX(stopmachine_mutex);

static int stopmachine(void *cpu)

{

struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,

				       unsigned int cpu)

{

	static DEFINE_MUTEX(stopmachine_mutex);

	struct stop_machine_data smdata;

	struct task_struct *p;

	smdata.data = data;

	init_completion(&smdata.done);

	down(&stopmachine_mutex);

	mutex_lock(&stopmachine_mutex);

	/* If they don't care which CPU fn runs on, bind to any online one. */

	if (cpu == NR_CPUS)

		wake_up_process(p);

		wait_for_completion(&smdata.done);

	}

	up(&stopmachine_mutex);

	mutex_unlock(&stopmachine_mutex);

	return p;

}