1 files changed, 448 insertions, 0 deletions
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
new file mode 100644
index 00000000000..3c8d61df447
--- /dev/null
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -0,0 +1,448 @@
+/*
+ * trace task wakeup timings
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *
+ *  Copyright (C) 2004-2006 Ingo Molnar
+ *  Copyright (C) 2004 William Lee Irwin III
+ */
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/marker.h>
+
+#include "trace.h"
+
+static struct trace_array	*wakeup_trace;
+static int __read_mostly	tracer_enabled;
+
+static struct task_struct	*wakeup_task;
+static int			wakeup_cpu;
+static unsigned			wakeup_prio = -1;
+
+static DEFINE_SPINLOCK(wakeup_lock);
+
+static void __wakeup_reset(struct trace_array *tr);
+
+#ifdef CONFIG_FTRACE
+/*
+ * irqsoff uses its own tracer function to keep the overhead down:
+ */
+static void
+wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
+{
+	struct trace_array *tr = wakeup_trace;
+	struct trace_array_cpu *data;
+	unsigned long flags;
+	long disabled;
+	int resched;
+	int cpu;
+
+	if (likely(!wakeup_task))
+		return;
+
+	resched = need_resched();
+	preempt_disable_notrace();
+
+	cpu = raw_smp_processor_id();
+	data = tr->data[cpu];
+	disabled = atomic_inc_return(&data->disabled);
+	if (unlikely(disabled != 1))
+		goto out;
+
+	spin_lock_irqsave(&wakeup_lock, flags);
+
+	if (unlikely(!wakeup_task))
+		goto unlock;
+
+	/*
+	 * The task can't disappear because it needs to
+	 * wake up first, and we have the wakeup_lock.
+	 */
+	if (task_cpu(wakeup_task) != cpu)
+		goto unlock;
+
+	trace_function(tr, data, ip, parent_ip, flags);
+
+ unlock:
+	spin_unlock_irqrestore(&wakeup_lock, flags);
+
+ out:
+	atomic_dec(&data->disabled);
+
+	/*
+	 * To prevent recursion from the scheduler, if the
+	 * resched flag was set before we entered, then
+	 * don't reschedule.
+	 */
+	if (resched)
+		preempt_enable_no_resched_notrace();
+	else
+		preempt_enable_notrace();
+}
+
+static struct ftrace_ops trace_ops __read_mostly =
+{
+	.func = wakeup_tracer_call,
+};
+#endif /* CONFIG_FTRACE */
+
+/*
+ * Should this new latency be reported/recorded?
+ */
+static int report_latency(cycle_t delta)
+{
+	if (tracing_thresh) {
+		if (delta < tracing_thresh)
+			return 0;
+	} else {
+		if (delta <= tracing_max_latency)
+			return 0;
+	}
+	return 1;
+}
+
+static void notrace
+wakeup_sched_switch(void *private, void *rq, struct task_struct *prev,
+	struct task_struct *next)
+{
+	unsigned long latency = 0, t0 = 0, t1 = 0;
+	struct trace_array **ptr = private;
+	struct trace_array *tr = *ptr;
+	struct trace_array_cpu *data;
+	cycle_t T0, T1, delta;
+	unsigned long flags;
+	long disabled;
+	int cpu;
+
+	if (unlikely(!tracer_enabled))
+		return;
+
+	/*
+	 * When we start a new trace, we set wakeup_task to NULL
+	 * and then set tracer_enabled = 1. We want to make sure
+	 * that another CPU does not see the tracer_enabled = 1
+	 * and the wakeup_task with an older task, that might
+	 * actually be the same as next.
+	 */
+	smp_rmb();
+
+	if (next != wakeup_task)
+		return;
+
+	/* The task we are waiting for is waking up */
+	data = tr->data[wakeup_cpu];
+
+	/* disable local data, not wakeup_cpu data */
+	cpu = raw_smp_processor_id();
+	disabled = atomic_inc_return(&tr->data[cpu]->disabled);
+	if (likely(disabled != 1))
+		goto out;
+
+	spin_lock_irqsave(&wakeup_lock, flags);
+
+	/* We could race with grabbing wakeup_lock */
+	if (unlikely(!tracer_enabled || next != wakeup_task))
+		goto out_unlock;
+
+	trace_function(tr, data, CALLER_ADDR1, CALLER_ADDR2, flags);
+
+	/*
+	 * usecs conversion is slow so we try to delay the conversion
+	 * as long as possible:
+	 */
+	T0 = data->preempt_timestamp;
+	T1 = ftrace_now(cpu);
+	delta = T1-T0;
+
+	if (!report_latency(delta))
+		goto out_unlock;
+
+	latency = nsecs_to_usecs(delta);
+
+	tracing_max_latency = delta;
+	t0 = nsecs_to_usecs(T0);
+	t1 = nsecs_to_usecs(T1);
+
+	update_max_tr(tr, wakeup_task, wakeup_cpu);
+
+out_unlock:
+	__wakeup_reset(tr);
+	spin_unlock_irqrestore(&wakeup_lock, flags);
+out:
+	atomic_dec(&tr->data[cpu]->disabled);
+}
+
+static notrace void
+sched_switch_callback(void *probe_data, void *call_data,
+		      const char *format, va_list *args)
+{
+	struct task_struct *prev;
+	struct task_struct *next;
+	struct rq *__rq;
+
+	/* skip prev_pid %d next_pid %d prev_state %ld */
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, long);
+	__rq = va_arg(*args, typeof(__rq));
+	prev = va_arg(*args, typeof(prev));
+	next = va_arg(*args, typeof(next));
+
+	tracing_record_cmdline(prev);
+
+	/*
+	 * If tracer_switch_func only points to the local
+	 * switch func, it still needs the ptr passed to it.
+	 */
+	wakeup_sched_switch(probe_data, __rq, prev, next);
+}
+
+static void __wakeup_reset(struct trace_array *tr)
+{
+	struct trace_array_cpu *data;
+	int cpu;
+
+	assert_spin_locked(&wakeup_lock);
+
+	for_each_possible_cpu(cpu) {
+		data = tr->data[cpu];
+		tracing_reset(data);
+	}
+
+	wakeup_cpu = -1;
+	wakeup_prio = -1;
+
+	if (wakeup_task)
+		put_task_struct(wakeup_task);
+
+	wakeup_task = NULL;
+}
+
+static void wakeup_reset(struct trace_array *tr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&wakeup_lock, flags);
+	__wakeup_reset(tr);
+	spin_unlock_irqrestore(&wakeup_lock, flags);
+}
+
+static void
+wakeup_check_start(struct trace_array *tr, struct task_struct *p,
+		   struct task_struct *curr)
+{
+	int cpu = smp_processor_id();
+	unsigned long flags;
+	long disabled;
+
+	if (likely(!rt_task(p)) ||
+			p->prio >= wakeup_prio ||
+			p->prio >= curr->prio)
+		return;
+
+	disabled = atomic_inc_return(&tr->data[cpu]->disabled);
+	if (unlikely(disabled != 1))
+		goto out;
+
+	/* interrupts should be off from try_to_wake_up */
+	spin_lock(&wakeup_lock);
+
+	/* check for races. */
+	if (!tracer_enabled || p->prio >= wakeup_prio)
+		goto out_locked;
+
+	/* reset the trace */
+	__wakeup_reset(tr);
+
+	wakeup_cpu = task_cpu(p);
+	wakeup_prio = p->prio;
+
+	wakeup_task = p;
+	get_task_struct(wakeup_task);
+
+	local_save_flags(flags);
+
+	tr->data[wakeup_cpu]->preempt_timestamp = ftrace_now(cpu);
+	trace_function(tr, tr->data[wakeup_cpu],
+		       CALLER_ADDR1, CALLER_ADDR2, flags);
+
+out_locked:
+	spin_unlock(&wakeup_lock);
+out:
+	atomic_dec(&tr->data[cpu]->disabled);
+}
+
+static notrace void
+wake_up_callback(void *probe_data, void *call_data,
+		 const char *format, va_list *args)
+{
+	struct trace_array **ptr = probe_data;
+	struct trace_array *tr = *ptr;
+	struct task_struct *curr;
+	struct task_struct *task;
+	struct rq *__rq;
+
+	if (likely(!tracer_enabled))
+		return;
+
+	/* Skip pid %d state %ld */
+	(void)va_arg(*args, int);
+	(void)va_arg(*args, long);
+	/* now get the meat: "rq %p task %p rq->curr %p" */
+	__rq = va_arg(*args, typeof(__rq));
+	task = va_arg(*args, typeof(task));
+	curr = va_arg(*args, typeof(curr));
+
+	tracing_record_cmdline(task);
+	tracing_record_cmdline(curr);
+
+	wakeup_check_start(tr, task, curr);
+}
+
+static void start_wakeup_tracer(struct trace_array *tr)
+{
+	int ret;
+
+	ret = marker_probe_register("kernel_sched_wakeup",
+			"pid %d state %ld ## rq %p task %p rq->curr %p",
+			wake_up_callback,
+			&wakeup_trace);
+	if (ret) {
+		pr_info("wakeup trace: Couldn't add marker"
+			" probe to kernel_sched_wakeup\n");
+		return;
+	}
+
+	ret = marker_probe_register("kernel_sched_wakeup_new",
+			"pid %d state %ld ## rq %p task %p rq->curr %p",
+			wake_up_callback,
+			&wakeup_trace);
+	if (ret) {
+		pr_info("wakeup trace: Couldn't add marker"
+			" probe to kernel_sched_wakeup_new\n");
+		goto fail_deprobe;
+	}
+
+	ret = marker_probe_register("kernel_sched_schedule",
+		"prev_pid %d next_pid %d prev_state %ld "
+		"## rq %p prev %p next %p",
+		sched_switch_callback,
+		&wakeup_trace);
+	if (ret) {
+		pr_info("sched trace: Couldn't add marker"
+			" probe to kernel_sched_schedule\n");
+		goto fail_deprobe_wake_new;
+	}
+
+	wakeup_reset(tr);
+
+	/*
+	 * Don't let the tracer_enabled = 1 show up before
+	 * the wakeup_task is reset. This may be overkill since
+	 * wakeup_reset does a spin_unlock after setting the
+	 * wakeup_task to NULL, but I want to be safe.
+	 * This is a slow path anyway.
+	 */
+	smp_wmb();
+
+	register_ftrace_function(&trace_ops);
+
+	tracer_enabled = 1;
+
+	return;
+fail_deprobe_wake_new:
+	marker_probe_unregister("kernel_sched_wakeup_new",
+				wake_up_callback,
+				&wakeup_trace);
+fail_deprobe:
+	marker_probe_unregister("kernel_sched_wakeup",
+				wake_up_callback,
+				&wakeup_trace);
+}
+
+static void stop_wakeup_tracer(struct trace_array *tr)
+{
+	tracer_enabled = 0;
+	unregister_ftrace_function(&trace_ops);
+	marker_probe_unregister("kernel_sched_schedule",
+				sched_switch_callback,
+				&wakeup_trace);
+	marker_probe_unregister("kernel_sched_wakeup_new",
+				wake_up_callback,
+				&wakeup_trace);
+	marker_probe_unregister("kernel_sched_wakeup",
+				wake_up_callback,
+				&wakeup_trace);
+}
+
+static void wakeup_tracer_init(struct trace_array *tr)
+{
+	wakeup_trace = tr;
+
+	if (tr->ctrl)
+		start_wakeup_tracer(tr);
+}
+
+static void wakeup_tracer_reset(struct trace_array *tr)
+{
+	if (tr->ctrl) {
+		stop_wakeup_tracer(tr);
+		/* make sure we put back any tasks we are tracing */
+		wakeup_reset(tr);
+	}
+}
+
+static void wakeup_tracer_ctrl_update(struct trace_array *tr)
+{
+	if (tr->ctrl)
+		start_wakeup_tracer(tr);
+	else
+		stop_wakeup_tracer(tr);
+}
+
+static void wakeup_tracer_open(struct trace_iterator *iter)
+{
+	/* stop the trace while dumping */
+	if (iter->tr->ctrl)
+		stop_wakeup_tracer(iter->tr);
+}
+
+static void wakeup_tracer_close(struct trace_iterator *iter)
+{
+	/* forget about any processes we were recording */
+	if (iter->tr->ctrl)
+		start_wakeup_tracer(iter->tr);
+}
+
+static struct tracer wakeup_tracer __read_mostly =
+{
+	.name		= "wakeup",
+	.init		= wakeup_tracer_init,
+	.reset		= wakeup_tracer_reset,
+	.open		= wakeup_tracer_open,
+	.close		= wakeup_tracer_close,
+	.ctrl_update	= wakeup_tracer_ctrl_update,
+	.print_max	= 1,
+#ifdef CONFIG_FTRACE_SELFTEST
+	.selftest    = trace_selftest_startup_wakeup,
+#endif
+};
+
+__init static int init_wakeup_tracer(void)
+{
+	int ret;
+
+	ret = register_tracer(&wakeup_tracer);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+device_initcall(init_wakeup_tracer);