kernel/trace/trace_selftest.c - arm/linux-arm64-legacy - Git at Google

 /* Include in trace.c */

 #include <linux/kthread.h>
 #include <linux/delay.h>

 static inline int trace_valid_entry(struct trace_entry *entry)
 {
 	switch (entry->type) {
 	case TRACE_FN:
 	case TRACE_CTX:
 	case TRACE_WAKE:
 	case TRACE_STACK:
 	case TRACE_SPECIAL:
 		return 1;
 	}
 	return 0;
 }

 static int
 trace_test_buffer_cpu(struct trace_array *tr, struct trace_array_cpu *data)
 {
 	struct trace_entry *entries;
 	struct page *page;
 	int idx = 0;
 	int i;

 	BUG_ON(list_empty(&data->trace_pages));
 	page = list_entry(data->trace_pages.next, struct page, lru);
 	entries = page_address(page);

 	check_pages(data);
 	if (head_page(data) != entries)
 		goto failed;

 	/*
 	 * The starting trace buffer always has valid elements,
 	 * if any element exists.
 	 */
 	entries = head_page(data);

 	for (i = 0; i < tr->entries; i++) {

 		if (i < data->trace_idx && !trace_valid_entry(&entries[idx])) {
 			printk(KERN_CONT ".. invalid entry %d ",
 				entries[idx].type);
 			goto failed;
 		}

 		idx++;
 		if (idx >= ENTRIES_PER_PAGE) {
 			page = virt_to_page(entries);
 			if (page->lru.next == &data->trace_pages) {
 				if (i != tr->entries - 1) {
 					printk(KERN_CONT ".. entries buffer mismatch");
 					goto failed;
 				}
 			} else {
 				page = list_entry(page->lru.next, struct page, lru);
 				entries = page_address(page);
 			}
 			idx = 0;
 		}
 	}

 	page = virt_to_page(entries);
 	if (page->lru.next != &data->trace_pages) {
 		printk(KERN_CONT ".. too many entries");
 		goto failed;
 	}

 	return 0;

  failed:
 	/* disable tracing */
 	tracing_disabled = 1;
 	printk(KERN_CONT ".. corrupted trace buffer .. ");
 	return -1;
 }

 /*
  * Test the trace buffer to see if all the elements
  * are still sane.
  */
 static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
 {
 	unsigned long flags, cnt = 0;
 	int cpu, ret = 0;

 	/* Don't allow flipping of max traces now */
 	raw_local_irq_save(flags);
 	__raw_spin_lock(&ftrace_max_lock);
 	for_each_possible_cpu(cpu) {
 		if (!head_page(tr->data[cpu]))
 			continue;

 		cnt += tr->data[cpu]->trace_idx;

 		ret = trace_test_buffer_cpu(tr, tr->data[cpu]);
 		if (ret)
 			break;
 	}
 	__raw_spin_unlock(&ftrace_max_lock);
 	raw_local_irq_restore(flags);

 	if (count)
 		*count = cnt;

 	return ret;
 }

 #ifdef CONFIG_FTRACE

 #ifdef CONFIG_DYNAMIC_FTRACE

 #define __STR(x) #x
 #define STR(x) __STR(x)

 /* Test dynamic code modification and ftrace filters */
 int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
 					   struct trace_array *tr,
 					   int (*func)(void))
 {
 	unsigned long count;
 	int ret;
 	int save_ftrace_enabled = ftrace_enabled;
 	int save_tracer_enabled = tracer_enabled;
 	char *func_name;

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

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

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

 	/* update the records */
 	ret = ftrace_force_update();
 	if (ret) {
 		printk(KERN_CONT ".. ftraced failed .. ");
 		return ret;
 	}

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

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

 	/* enable tracing */
 	tr->ctrl = 1;
 	trace->init(tr);
 	/* Sleep for a 1/10 of a second */
 	msleep(100);

 	/* we should have nothing in the buffer */
 	ret = trace_test_buffer(tr, &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. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	ftrace_enabled = 0;

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

 	/* we should only have one item */
 	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;

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

 	return ret;
 }
 #else
 # define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })
 #endif /* CONFIG_DYNAMIC_FTRACE */
 /*
  * 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)
 {
 	unsigned long count;
 	int ret;
 	int save_ftrace_enabled = ftrace_enabled;
 	int save_tracer_enabled = tracer_enabled;

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

 	/* force the recorded functions to be traced */
 	ret = ftrace_force_update();
 	if (ret) {
 		printk(KERN_CONT ".. ftraced failed .. ");
 		return ret;
 	}

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

 	tr->ctrl = 1;
 	trace->init(tr);
 	/* Sleep for a 1/10 of a second */
 	msleep(100);
 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	ftrace_enabled = 0;

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

 	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;
 }
 #endif /* CONFIG_FTRACE */

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

 	/* start the tracing */
 	tr->ctrl = 1;
 	trace->init(tr);
 	/* reset the max latency */
 	tracing_max_latency = 0;
 	/* disable interrupts for a bit */
 	local_irq_disable();
 	udelay(100);
 	local_irq_enable();
 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check both trace buffers */
 	ret = trace_test_buffer(tr, NULL);
 	if (!ret)
 		ret = trace_test_buffer(&max_tr, &count);
 	trace->reset(tr);

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

 	tracing_max_latency = save_max;

 	return ret;
 }
 #endif /* CONFIG_IRQSOFF_TRACER */

 #ifdef CONFIG_PREEMPT_TRACER
 int
 trace_selftest_startup_preemptoff(struct tracer *trace, struct trace_array *tr)
 {
 	unsigned long save_max = tracing_max_latency;
 	unsigned long count;
 	int ret;

 	/* start the tracing */
 	tr->ctrl = 1;
 	trace->init(tr);
 	/* reset the max latency */
 	tracing_max_latency = 0;
 	/* disable preemption for a bit */
 	preempt_disable();
 	udelay(100);
 	preempt_enable();
 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check both trace buffers */
 	ret = trace_test_buffer(tr, NULL);
 	if (!ret)
 		ret = trace_test_buffer(&max_tr, &count);
 	trace->reset(tr);

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

 	tracing_max_latency = save_max;

 	return ret;
 }
 #endif /* CONFIG_PREEMPT_TRACER */

 #if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
 int
 trace_selftest_startup_preemptirqsoff(struct tracer *trace, struct trace_array *tr)
 {
 	unsigned long save_max = tracing_max_latency;
 	unsigned long count;
 	int ret;

 	/* start the tracing */
 	tr->ctrl = 1;
 	trace->init(tr);

 	/* reset the max latency */
 	tracing_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 tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check both trace buffers */
 	ret = trace_test_buffer(tr, NULL);
 	if (ret)
 		goto out;

 	ret = trace_test_buffer(&max_tr, &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 */
 	tracing_max_latency = 0;
 	tr->ctrl = 1;
 	trace->ctrl_update(tr);
 	preempt_disable();
 	local_irq_disable();
 	udelay(100);
 	preempt_enable();
 	/* reverse the order of preempt vs irqs */
 	local_irq_enable();

 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check both trace buffers */
 	ret = trace_test_buffer(tr, NULL);
 	if (ret)
 		goto out;

 	ret = trace_test_buffer(&max_tr, &count);

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

  out:
 	trace->reset(tr);
 	tracing_max_latency = save_max;

 	return ret;
 }
 #endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */

 #ifdef CONFIG_SCHED_TRACER
 static int trace_wakeup_test_thread(void *data)
 {
 	/* Make this a RT thread, doesn't need to be too high */
 	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 */
 	tr->ctrl = 1;
 	trace->init(tr);
 	/* 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);

 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check both trace buffers */
 	ret = trace_test_buffer(tr, NULL);
 	if (!ret)
 		ret = trace_test_buffer(&max_tr, &count);


 	trace->reset(tr);

 	tracing_max_latency = save_max;

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

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

 	return ret;
 }
 #endif /* CONFIG_SCHED_TRACER */

 #ifdef CONFIG_CONTEXT_SWITCH_TRACER
 int
 trace_selftest_startup_sched_switch(struct tracer *trace, struct trace_array *tr)
 {
 	unsigned long count;
 	int ret;

 	/* start the tracing */
 	tr->ctrl = 1;
 	trace->init(tr);
 	/* Sleep for a 1/10 of a second */
 	msleep(100);
 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check the trace buffer */
 	ret = trace_test_buffer(tr, &count);
 	trace->reset(tr);

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

 	return ret;
 }
 #endif /* CONFIG_CONTEXT_SWITCH_TRACER */

 #ifdef CONFIG_SYSPROF_TRACER
 int
 trace_selftest_startup_sysprof(struct tracer *trace, struct trace_array *tr)
 {
 	unsigned long count;
 	int ret;

 	/* start the tracing */
 	tr->ctrl = 1;
 	trace->init(tr);
 	/* Sleep for a 1/10 of a second */
 	msleep(100);
 	/* stop the tracing. */
 	tr->ctrl = 0;
 	trace->ctrl_update(tr);
 	/* check the trace buffer */
 	ret = trace_test_buffer(tr, &count);
 	trace->reset(tr);

 	return ret;
 }
 #endif /* CONFIG_SYSPROF_TRACER */
	/* Include in trace.c */

	#include <linux/kthread.h>
	#include <linux/delay.h>

	static inline int trace_valid_entry(struct trace_entry *entry)
	{
	switch (entry->type) {
	case TRACE_FN:
	case TRACE_CTX:
	case TRACE_WAKE:
	case TRACE_STACK:
	case TRACE_SPECIAL:
	return 1;
	}
	return 0;
	}

	static int
	trace_test_buffer_cpu(struct trace_array tr, struct trace_array_cpu data)
	{
	struct trace_entry *entries;
	struct page *page;
	int idx = 0;
	int i;

	BUG_ON(list_empty(&data->trace_pages));
	page = list_entry(data->trace_pages.next, struct page, lru);
	entries = page_address(page);

	check_pages(data);
	if (head_page(data) != entries)
	goto failed;

	/*
	* The starting trace buffer always has valid elements,
	* if any element exists.
	*/
	entries = head_page(data);

	for (i = 0; i < tr->entries; i++) {

	if (i < data->trace_idx && !trace_valid_entry(&entries[idx])) {
	printk(KERN_CONT ".. invalid entry %d ",
	entries[idx].type);
	goto failed;
	}

	idx++;
	if (idx >= ENTRIES_PER_PAGE) {
	page = virt_to_page(entries);
	if (page->lru.next == &data->trace_pages) {
	if (i != tr->entries - 1) {
	printk(KERN_CONT ".. entries buffer mismatch");
	goto failed;
	}
	} else {
	page = list_entry(page->lru.next, struct page, lru);
	entries = page_address(page);
	}
	idx = 0;
	}
	}

	page = virt_to_page(entries);
	if (page->lru.next != &data->trace_pages) {
	printk(KERN_CONT ".. too many entries");
	goto failed;
	}

	return 0;

	failed:
	/* disable tracing */
	tracing_disabled = 1;
	printk(KERN_CONT ".. corrupted trace buffer .. ");
	return -1;
	}

	/*
	* Test the trace buffer to see if all the elements
	* are still sane.
	*/
	static int trace_test_buffer(struct trace_array tr, unsigned long count)
	{
	unsigned long flags, cnt = 0;
	int cpu, ret = 0;

	/* Don't allow flipping of max traces now */
	raw_local_irq_save(flags);
	__raw_spin_lock(&ftrace_max_lock);
	for_each_possible_cpu(cpu) {
	if (!head_page(tr->data[cpu]))
	continue;

	cnt += tr->data[cpu]->trace_idx;

	ret = trace_test_buffer_cpu(tr, tr->data[cpu]);
	if (ret)
	break;
	}
	__raw_spin_unlock(&ftrace_max_lock);
	raw_local_irq_restore(flags);

	if (count)
	*count = cnt;

	return ret;
	}

	#ifdef CONFIG_FTRACE

	#ifdef CONFIG_DYNAMIC_FTRACE

	#define __STR(x) #x
	#define STR(x) __STR(x)

	/* Test dynamic code modification and ftrace filters */
	int trace_selftest_startup_dynamic_tracing(struct tracer *trace,
	struct trace_array *tr,
	int (*func)(void))
	{
	unsigned long count;
	int ret;
	int save_ftrace_enabled = ftrace_enabled;
	int save_tracer_enabled = tracer_enabled;
	char *func_name;

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

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

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

	/* update the records */
	ret = ftrace_force_update();
	if (ret) {
	printk(KERN_CONT ".. ftraced failed .. ");
	return ret;
	}

	/*
	* Some archs coughPowerPCcough add charachters to the
	* start of the function names. We simply put a '*' to
	* accomodate them.
	*/
	func_name = "*" STR(DYN_FTRACE_TEST_NAME);

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

	/* enable tracing */
	tr->ctrl = 1;
	trace->init(tr);
	/* Sleep for a 1/10 of a second */
	msleep(100);

	/* we should have nothing in the buffer */
	ret = trace_test_buffer(tr, &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. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	ftrace_enabled = 0;

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

	/* we should only have one item */
	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;

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

	return ret;
	}
	#else
	# define trace_selftest_startup_dynamic_tracing(trace, tr, func) ({ 0; })
	#endif /* CONFIG_DYNAMIC_FTRACE */
	/*
	* 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)
	{
	unsigned long count;
	int ret;
	int save_ftrace_enabled = ftrace_enabled;
	int save_tracer_enabled = tracer_enabled;

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

	/* force the recorded functions to be traced */
	ret = ftrace_force_update();
	if (ret) {
	printk(KERN_CONT ".. ftraced failed .. ");
	return ret;
	}

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

	tr->ctrl = 1;
	trace->init(tr);
	/* Sleep for a 1/10 of a second */
	msleep(100);
	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	ftrace_enabled = 0;

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

	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;
	}
	#endif /* CONFIG_FTRACE */

	#ifdef CONFIG_IRQSOFF_TRACER
	int
	trace_selftest_startup_irqsoff(struct tracer trace, struct trace_array tr)
	{
	unsigned long save_max = tracing_max_latency;
	unsigned long count;
	int ret;

	/* start the tracing */
	tr->ctrl = 1;
	trace->init(tr);
	/* reset the max latency */
	tracing_max_latency = 0;
	/* disable interrupts for a bit */
	local_irq_disable();
	udelay(100);
	local_irq_enable();
	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
	ret = trace_test_buffer(&max_tr, &count);
	trace->reset(tr);

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

	tracing_max_latency = save_max;

	return ret;
	}
	#endif /* CONFIG_IRQSOFF_TRACER */

	#ifdef CONFIG_PREEMPT_TRACER
	int
	trace_selftest_startup_preemptoff(struct tracer trace, struct trace_array tr)
	{
	unsigned long save_max = tracing_max_latency;
	unsigned long count;
	int ret;

	/* start the tracing */
	tr->ctrl = 1;
	trace->init(tr);
	/* reset the max latency */
	tracing_max_latency = 0;
	/* disable preemption for a bit */
	preempt_disable();
	udelay(100);
	preempt_enable();
	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
	ret = trace_test_buffer(&max_tr, &count);
	trace->reset(tr);

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

	tracing_max_latency = save_max;

	return ret;
	}
	#endif /* CONFIG_PREEMPT_TRACER */

	#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
	int
	trace_selftest_startup_preemptirqsoff(struct tracer trace, struct trace_array tr)
	{
	unsigned long save_max = tracing_max_latency;
	unsigned long count;
	int ret;

	/* start the tracing */
	tr->ctrl = 1;
	trace->init(tr);

	/* reset the max latency */
	tracing_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 tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (ret)
	goto out;

	ret = trace_test_buffer(&max_tr, &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 */
	tracing_max_latency = 0;
	tr->ctrl = 1;
	trace->ctrl_update(tr);
	preempt_disable();
	local_irq_disable();
	udelay(100);
	preempt_enable();
	/* reverse the order of preempt vs irqs */
	local_irq_enable();

	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (ret)
	goto out;

	ret = trace_test_buffer(&max_tr, &count);

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

	out:
	trace->reset(tr);
	tracing_max_latency = save_max;

	return ret;
	}
	#endif /* CONFIG_IRQSOFF_TRACER && CONFIG_PREEMPT_TRACER */

	#ifdef CONFIG_SCHED_TRACER
	static int trace_wakeup_test_thread(void *data)
	{
	/* Make this a RT thread, doesn't need to be too high */
	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 */
	tr->ctrl = 1;
	trace->init(tr);
	/* 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);

	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check both trace buffers */
	ret = trace_test_buffer(tr, NULL);
	if (!ret)
	ret = trace_test_buffer(&max_tr, &count);


	trace->reset(tr);

	tracing_max_latency = save_max;

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

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

	return ret;
	}
	#endif /* CONFIG_SCHED_TRACER */

	#ifdef CONFIG_CONTEXT_SWITCH_TRACER
	int
	trace_selftest_startup_sched_switch(struct tracer trace, struct trace_array tr)
	{
	unsigned long count;
	int ret;

	/* start the tracing */
	tr->ctrl = 1;
	trace->init(tr);
	/* Sleep for a 1/10 of a second */
	msleep(100);
	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check the trace buffer */
	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);

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

	return ret;
	}
	#endif /* CONFIG_CONTEXT_SWITCH_TRACER */

	#ifdef CONFIG_SYSPROF_TRACER
	int
	trace_selftest_startup_sysprof(struct tracer trace, struct trace_array tr)
	{
	unsigned long count;
	int ret;

	/* start the tracing */
	tr->ctrl = 1;
	trace->init(tr);
	/* Sleep for a 1/10 of a second */
	msleep(100);
	/* stop the tracing. */
	tr->ctrl = 0;
	trace->ctrl_update(tr);
	/* check the trace buffer */
	ret = trace_test_buffer(tr, &count);
	trace->reset(tr);

	return ret;
	}
	#endif /* CONFIG_SYSPROF_TRACER */