Ejemplo n.º 1
0
/*
 * Pretty much the same than for the function tracer from which the selftest
 * has been borrowed.
 */
int
trace_selftest_startup_function_graph(struct tracer *trace,
					struct trace_array *tr)
{
	int ret;
	unsigned long count;

	/*
	 * Simulate the init() callback but we attach a watchdog callback
	 * to detect and recover from possible hangs
	 */
	tracing_reset_online_cpus(tr);
	ret = register_ftrace_graph(&trace_graph_return,
				    &trace_graph_entry_watchdog);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}
	tracing_start_cmdline_record();

	/* Sleep for a 1/10 of a second */
	msleep(100);

	/* Have we just recovered from a hang? */
	if (graph_hang_thresh > GRAPH_MAX_FUNC_TEST) {
		tracing_selftest_disabled = true;
		ret = -1;
		goto out;
	}

	tracing_stop();

	/* check the trace buffer */
	ret = trace_test_buffer(tr, &count);

	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

	/* Don't test dynamic tracing, the function tracer already did */

out:
	/* Stop it if we failed */
	if (ret)
		ftrace_graph_stop();

	return ret;
}
Ejemplo n.º 2
0
/*
 * Simple verification test of ftrace function tracer.
 * Enable ftrace, sleep 1/10 second, and then read the trace
 * buffer to see if all is in order.
 */
int
trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
{
	int save_ftrace_enabled = ftrace_enabled;
	int save_tracer_enabled = tracer_enabled;
	unsigned long count;
	int ret;

	/* make sure msleep has been recorded */
	msleep(1);

	/* start the tracing */
	ftrace_enabled = 1;
	tracer_enabled = 1;

	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}

	/* Sleep for a 1/10 of a second */
	msleep(100);
	/* stop the tracing. */
	tracing_stop();
	ftrace_enabled = 0;

	/* check the trace buffer */
	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

	ret = trace_selftest_startup_dynamic_tracing(trace, tr,
						     DYN_FTRACE_TEST_NAME);

 out:
	ftrace_enabled = save_ftrace_enabled;
	tracer_enabled = save_tracer_enabled;

	/* kill ftrace totally if we failed */
	if (ret)
		ftrace_kill();

	return ret;
}
Ejemplo n.º 3
0
int
trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tracing_max_latency;
	unsigned long count;
	int ret;

	/*
	 * Now that the big kernel lock is no longer preemptable,
	 * and this is called with the BKL held, it will always
	 * fail. If preemption is already disabled, simply
	 * pass the test. When the BKL is removed, or becomes
	 * preemptible again, we will once again test this,
	 * so keep it in.
	 */
	if (preempt_count()) {
		printk(KERN_CONT "can not test ... force ");
		return 0;
	}

	/* start the tracing */
	ret = trace->init(tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	/* reset the max latency */
	tracing_max_latency = 0;
	/* disable preemption for a bit */
	preempt_disable();
	udelay(100);
	preempt_enable();
	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
		ret = trace_test_buffer(&max_tr, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	tracing_max_latency = save_max;

	return ret;
}
Ejemplo n.º 4
0
int
trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
{
	int save_ftrace_enabled = ftrace_enabled;
	int save_tracer_enabled = tracer_enabled;
	unsigned long count;
	int ret;

	
	msleep(1);

	
	ftrace_enabled = 1;
	tracer_enabled = 1;

	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}

	
	msleep(100);
	
	tracing_stop();
	ftrace_enabled = 0;

	
	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

	ret = trace_selftest_startup_dynamic_tracing(trace, tr,
						     DYN_FTRACE_TEST_NAME);

 out:
	ftrace_enabled = save_ftrace_enabled;
	tracer_enabled = save_tracer_enabled;

	
	if (ret)
		ftrace_kill();

	return ret;
}
Ejemplo n.º 5
0
int
trace_selftest_startup_function_graph(struct tracer *trace,
					struct trace_array *tr)
{
	int ret;
	unsigned long count;

	
	tracing_reset_online_cpus(tr);
	set_graph_array(tr);
	ret = register_ftrace_graph(&trace_graph_return,
				    &trace_graph_entry_watchdog);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}
	tracing_start_cmdline_record();

	
	msleep(100);

	
	if (graph_hang_thresh > GRAPH_MAX_FUNC_TEST) {
		tracing_selftest_disabled = true;
		ret = -1;
		goto out;
	}

	tracing_stop();

	
	ret = trace_test_buffer(tr, &count);

	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

	

out:
	
	if (ret)
		ftrace_graph_stop();

	return ret;
}
Ejemplo n.º 6
0
int
trace_selftest_startup_hw_branches(struct tracer *trace,
				   struct trace_array *tr)
{
	struct trace_iterator *iter;
	struct tracer tracer;
	unsigned long count;
	int ret;

	if (!trace->open) {
		printk(KERN_CONT "missing open function...");
		return -1;
	}

	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	
	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
	if (!iter)
		return -ENOMEM;

	memcpy(&tracer, trace, sizeof(tracer));

	iter->trace = &tracer;
	iter->tr = tr;
	iter->pos = -1;
	mutex_init(&iter->mutex);

	trace->open(iter);

	mutex_destroy(&iter->mutex);
	kfree(iter);

	tracing_stop();

	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT "no entries found..");
		ret = -1;
	}

	return ret;
}
Ejemplo n.º 7
0
int
trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tracing_max_latency;
	unsigned long count;
	int ret;

	
	if (preempt_count()) {
		printk(KERN_CONT "can not test ... force ");
		return 0;
	}

	
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	
	tracing_max_latency = 0;
	
	preempt_disable();
	udelay(100);
	preempt_enable();

	
	trace->stop(tr);
	
	tracing_stop();
	
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
		ret = trace_test_buffer(&max_tr, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	tracing_max_latency = save_max;

	return ret;
}
int
trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tracing_max_latency;
	unsigned long count;
	int ret;

	/*                   */
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	/*                       */
	tracing_max_latency = 0;
	/*                              */
	local_irq_disable();
	udelay(100);
	local_irq_enable();

	/*
                                                 
                                                     
                                                               
                                                
  */
	trace->stop(tr);
	/*                   */
	tracing_stop();
	/*                          */
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
		ret = trace_test_buffer(&max_tr, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	tracing_max_latency = save_max;

	return ret;
}
Ejemplo n.º 9
0
int
trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tr->max_latency;
	unsigned long count;
	int ret;

	/* start the tracing */
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	/* reset the max latency */
	tr->max_latency = 0;
	/* disable interrupts for a bit */
	local_irq_disable();
	udelay(100);
	local_irq_enable();

	/*
	 * Stop the tracer to avoid a warning subsequent
	 * to buffer flipping failure because tracing_stop()
	 * disables the tr and max buffers, making flipping impossible
	 * in case of parallels max irqs off latencies.
	 */
	trace->stop(tr);
	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(&tr->trace_buffer, NULL);
	if (!ret)
		ret = trace_test_buffer(&tr->max_buffer, &count);
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	tr->max_latency = save_max;

	return ret;
}
Ejemplo n.º 10
0
int
trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr)
{
	unsigned long count;
	int ret;

	/* start the tracing */
	ret = trace->init(tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	/* Sleep for a 1/10 of a second */
	msleep(100);
	/* stop the tracing. */
	tracing_stop();
	/* check the trace buffer */
	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);
	tracing_start();

	return ret;
}
Ejemplo n.º 11
0
int
trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tr->max_latency;
	unsigned long count;
	int ret;

	/*
	 * Now that the big kernel lock is no longer preemptable,
	 * and this is called with the BKL held, it will always
	 * fail. If preemption is already disabled, simply
	 * pass the test. When the BKL is removed, or becomes
	 * preemptible again, we will once again test this,
	 * so keep it in.
	 */
	if (preempt_count()) {
		printk(KERN_CONT "can not test ... force ");
		return 0;
	}

	/* start the tracing */
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out_no_start;
	}

	/* reset the max latency */
	tr->max_latency = 0;

	/* disable preemption and interrupts for a bit */
	preempt_disable();
	local_irq_disable();
	udelay(100);
	preempt_enable();
	/* reverse the order of preempt vs irqs */
	local_irq_enable();

	/*
	 * Stop the tracer to avoid a warning subsequent
	 * to buffer flipping failure because tracing_stop()
	 * disables the tr and max buffers, making flipping impossible
	 * in case of parallels max irqs/preempt off latencies.
	 */
	trace->stop(tr);
	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(&tr->trace_buffer, NULL);
	if (ret)
		goto out;

	ret = trace_test_buffer(&tr->max_buffer, &count);
	if (ret)
		goto out;

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

	/* do the test by disabling interrupts first this time */
	tr->max_latency = 0;
	tracing_start();
	trace->start(tr);

	preempt_disable();
	local_irq_disable();
	udelay(100);
	preempt_enable();
	/* reverse the order of preempt vs irqs */
	local_irq_enable();

	trace->stop(tr);
	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(&tr->trace_buffer, NULL);
	if (ret)
		goto out;

	ret = trace_test_buffer(&tr->max_buffer, &count);

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

out:
	tracing_start();
out_no_start:
	trace->reset(tr);
	tr->max_latency = save_max;

	return ret;
}
Ejemplo n.º 12
0
/*
 * Simple verification test of ftrace function tracer.
 * Enable ftrace, sleep 1/10 second, and then read the trace
 * buffer to see if all is in order.
 */
__init int
trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
{
	int save_ftrace_enabled = ftrace_enabled;
	unsigned long count;
	int ret;

#ifdef CONFIG_DYNAMIC_FTRACE
	if (ftrace_filter_param) {
		printk(KERN_CONT " ... kernel command line filter set: force PASS ... ");
		return 0;
	}
#endif

	/* make sure msleep has been recorded */
	msleep(1);

	/* start the tracing */
	ftrace_enabled = 1;

	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}

	/* Sleep for a 1/10 of a second */
	msleep(100);
	/* stop the tracing. */
	tracing_stop();
	ftrace_enabled = 0;

	/* check the trace buffer */
	ret = trace_test_buffer(&tr->trace_buffer, &count);

	ftrace_enabled = 1;
	trace->reset(tr);
	tracing_start();

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
		goto out;
	}

	ret = trace_selftest_startup_dynamic_tracing(trace, tr,
						     DYN_FTRACE_TEST_NAME);
	if (ret)
		goto out;

	ret = trace_selftest_function_recursion();
	if (ret)
		goto out;

	ret = trace_selftest_function_regs();
 out:
	ftrace_enabled = save_ftrace_enabled;

	/* kill ftrace totally if we failed */
	if (ret)
		ftrace_kill();

	return ret;
}
Ejemplo n.º 13
0
/* Test dynamic code modification and ftrace filters */
static int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
						  struct trace_array *tr,
						  int (*func)(void))
{
	int save_ftrace_enabled = ftrace_enabled;
	unsigned long count;
	char *func_name;
	int ret;

	/* The ftrace test PASSED */
	printk(KERN_CONT "PASSED\n");
	pr_info("Testing dynamic ftrace: ");

	/* enable tracing, and record the filter function */
	ftrace_enabled = 1;

	/* passed in by parameter to fool gcc from optimizing */
	func();

	/*
	 * Some archs *cough*PowerPC*cough* add characters to the
	 * start of the function names. We simply put a '*' to
	 * accommodate them.
	 */
	func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);

	/* filter only on our function */
	ftrace_set_global_filter(func_name, strlen(func_name), 1);

	/* enable tracing */
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}

	/* Sleep for a 1/10 of a second */
	msleep(100);

	/* we should have nothing in the buffer */
	ret = trace_test_buffer(&tr->trace_buffer, &count);
	if (ret)
		goto out;

	if (count) {
		ret = -1;
		printk(KERN_CONT ".. filter did not filter .. ");
		goto out;
	}

	/* call our function again */
	func();

	/* sleep again */
	msleep(100);

	/* stop the tracing. */
	tracing_stop();
	ftrace_enabled = 0;

	/* check the trace buffer */
	ret = trace_test_buffer(&tr->trace_buffer, &count);

	ftrace_enabled = 1;
	tracing_start();

	/* we should only have one item */
	if (!ret && count != 1) {
		trace->reset(tr);
		printk(KERN_CONT ".. filter failed count=%ld ..", count);
		ret = -1;
		goto out;
	}

	/* Test the ops with global tracing running */
	ret = trace_selftest_ops(tr, 1);
	trace->reset(tr);

 out:
	ftrace_enabled = save_ftrace_enabled;

	/* Enable tracing on all functions again */
	ftrace_set_global_filter(NULL, 0, 1);

	/* Test the ops with global tracing off */
	if (!ret)
		ret = trace_selftest_ops(tr, 2);

	return ret;
}
Ejemplo n.º 14
0
int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
					   struct trace_array *tr,
					   int (*func)(void))
{
	int save_ftrace_enabled = ftrace_enabled;
	int save_tracer_enabled = tracer_enabled;
	unsigned long count;
	char *func_name;
	int ret;

	
	printk(KERN_CONT "PASSED\n");
	pr_info("Testing dynamic ftrace: ");

	
	ftrace_enabled = 1;
	tracer_enabled = 1;

	
	func();

	
	func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);

	
	ftrace_set_filter(func_name, strlen(func_name), 1);

	
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		goto out;
	}

	
	msleep(100);

	
	ret = trace_test_buffer(tr, &count);
	if (ret)
		goto out;

	if (count) {
		ret = -1;
		printk(KERN_CONT ".. filter did not filter .. ");
		goto out;
	}

	
	func();

	
	msleep(100);

	
	tracing_stop();
	ftrace_enabled = 0;

	
	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);
	tracing_start();

	
	if (!ret && count != 1) {
		printk(KERN_CONT ".. filter failed count=%ld ..", count);
		ret = -1;
		goto out;
	}

 out:
	ftrace_enabled = save_ftrace_enabled;
	tracer_enabled = save_tracer_enabled;

	
	ftrace_set_filter(NULL, 0, 1);

	return ret;
}
Ejemplo n.º 15
0
static int trace_wakeup_test_thread(void *data)
{
	/* Make this a RT thread, doesn't need to be too high */
	static const struct sched_param param = { .sched_priority = 5 };
	struct completion *x = data;

	sched_setscheduler(current, SCHED_FIFO, &param);

	/* Make it know we have a new prio */
	complete(x);

	/* now go to sleep and let the test wake us up */
	set_current_state(TASK_INTERRUPTIBLE);
	schedule();

	complete(x);

	/* we are awake, now wait to disappear */
	while (!kthread_should_stop()) {
		/*
		 * This is an RT task, do short sleeps to let
		 * others run.
		 */
		msleep(100);
	}

	return 0;
}

int
trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tracing_max_latency;
	struct task_struct *p;
	struct completion isrt;
	unsigned long count;
	int ret;

	init_completion(&isrt);

	/* create a high prio thread */
	p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
	if (IS_ERR(p)) {
		printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
		return -1;
	}

	/* make sure the thread is running at an RT prio */
	wait_for_completion(&isrt);

	/* start the tracing */
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	/* reset the max latency */
	tracing_max_latency = 0;

	while (p->on_rq) {
		/*
		 * Sleep to make sure the RT thread is asleep too.
		 * On virtual machines we can't rely on timings,
		 * but we want to make sure this test still works.
		 */
		msleep(100);
	}

	init_completion(&isrt);

	wake_up_process(p);

	/* Wait for the task to wake up */
	wait_for_completion(&isrt);

	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	printk("ret = %d\n", ret);
	if (!ret)
		ret = trace_test_buffer(&max_tr, &count);


	trace->reset(tr);
	tracing_start();

	tracing_max_latency = save_max;

	/* kill the thread */
	kthread_stop(p);

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	return ret;
}
Ejemplo n.º 16
0
static int trace_wakeup_test_thread(void *data)
{
	
	struct sched_param param = { .sched_priority = 5 };
	struct completion *x = data;

	sched_setscheduler(current, SCHED_FIFO, &param);

	
	complete(x);

	
	set_current_state(TASK_INTERRUPTIBLE);
	schedule();

	
	while (!kthread_should_stop()) {
		
		msleep(100);
	}

	return 0;
}

int
trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tracing_max_latency;
	struct task_struct *p;
	struct completion isrt;
	unsigned long count;
	int ret;

	init_completion(&isrt);

	
	p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
	if (IS_ERR(p)) {
		printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
		return -1;
	}

	
	wait_for_completion(&isrt);

	
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	
	tracing_max_latency = 0;

	
	msleep(100);

	

	wake_up_process(p);

	
	msleep(100);

	
	tracing_stop();
	
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
		ret = trace_test_buffer(&max_tr, &count);


	trace->reset(tr);
	tracing_start();

	tracing_max_latency = save_max;

	
	kthread_stop(p);

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	return ret;
}
Ejemplo n.º 17
0
static int trace_wakeup_test_thread(void *data)
{
	/* Make this a RT thread, doesn't need to be too high */
	static const struct sched_param param = { .sched_priority = 5 };
	struct completion *x = data;

	sched_setscheduler(current, SCHED_FIFO, &param);

	/* Make it know we have a new prio */
	complete(x);

	/* now go to sleep and let the test wake us up */
	set_current_state(TASK_INTERRUPTIBLE);
	schedule();

	/* we are awake, now wait to disappear */
	while (!kthread_should_stop()) {
		/*
		 * This is an RT task, do short sleeps to let
		 * others run.
		 */
		msleep(100);
	}

	return 0;
}

int
trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
{
	unsigned long save_max = tracing_max_latency;
	struct task_struct *p;
	struct completion isrt;
	unsigned long count;
	int ret;

	init_completion(&isrt);

	/* create a high prio thread */
	p = kthread_run(trace_wakeup_test_thread, &isrt, "ftrace-test");
	if (IS_ERR(p)) {
		printk(KERN_CONT "Failed to create ftrace wakeup test thread ");
		return -1;
	}

	/* make sure the thread is running at an RT prio */
	wait_for_completion(&isrt);

	/* start the tracing */
	ret = tracer_init(trace, tr);
	if (ret) {
		warn_failed_init_tracer(trace, ret);
		return ret;
	}

	/* reset the max latency */
	tracing_max_latency = 0;

	/* sleep to let the RT thread sleep too */
	msleep(100);

	/*
	 * Yes this is slightly racy. It is possible that for some
	 * strange reason that the RT thread we created, did not
	 * call schedule for 100ms after doing the completion,
	 * and we do a wakeup on a task that already is awake.
	 * But that is extremely unlikely, and the worst thing that
	 * happens in such a case, is that we disable tracing.
	 * Honestly, if this race does happen something is horrible
	 * wrong with the system.
	 */

	wake_up_process(p);

	/* give a little time to let the thread wake up */
	msleep(100);

	/* stop the tracing. */
	tracing_stop();
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
		ret = trace_test_buffer(&max_tr, &count);


	trace->reset(tr);
	tracing_start();

	tracing_max_latency = save_max;

	/* kill the thread */
	kthread_stop(p);

	if (!ret && !count) {
		printk(KERN_CONT ".. no entries found ..");
		ret = -1;
	}

	return ret;
}