/*
   * 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 <trace/events/sched.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 int			wakeup_current_cpu;

  static unsigned			wakeup_prio = -1;

  static int			wakeup_rt;

  static arch_spinlock_t wakeup_lock =

  	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;

  static void wakeup_reset(struct trace_array *tr);

  static void __wakeup_reset(struct trace_array *tr);

  static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
  static void wakeup_graph_return(struct ftrace_graph_ret *trace);

  static int save_lat_flag;

  #define TRACE_DISPLAY_GRAPH     1
  
  static struct tracer_opt trace_opts[] = {
  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  	/* display latency trace as call graph */
  	{ TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
  #endif
  	{ } /* Empty entry */
  };
  
  static struct tracer_flags tracer_flags = {
  	.val  = 0,
  	.opts = trace_opts,
  };
  
  #define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)

  #ifdef CONFIG_FUNCTION_TRACER

  /*

   * Prologue for the wakeup function tracers.
   *
   * Returns 1 if it is OK to continue, and preemption
   *            is disabled and data->disabled is incremented.
   *         0 if the trace is to be ignored, and preemption
   *            is not disabled and data->disabled is
   *            kept the same.
   *
   * Note, this function is also used outside this ifdef but
   *  inside the #ifdef of the function graph tracer below.
   *  This is OK, since the function graph tracer is
   *  dependent on the function tracer.

   */

  static int
  func_prolog_preempt_disable(struct trace_array *tr,
  			    struct trace_array_cpu **data,
  			    int *pc)

  {

  	long disabled;

  	int cpu;
  
  	if (likely(!wakeup_task))

  		return 0;

  	*pc = preempt_count();

  	preempt_disable_notrace();

  
  	cpu = raw_smp_processor_id();

  	if (cpu != wakeup_current_cpu)
  		goto out_enable;

  	*data = tr->data[cpu];
  	disabled = atomic_inc_return(&(*data)->disabled);

  	if (unlikely(disabled != 1))
  		goto out;

  	return 1;

  out:
  	atomic_dec(&(*data)->disabled);

  out_enable:
  	preempt_enable_notrace();
  	return 0;
  }
  
  /*
   * wakeup 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;
  	int pc;
  
  	if (!func_prolog_preempt_disable(tr, &data, &pc))
  		return;
  
  	local_irq_save(flags);
  	trace_function(tr, ip, parent_ip, flags, pc);

  	local_irq_restore(flags);

  	atomic_dec(&data->disabled);

  	preempt_enable_notrace();

  }
  
  static struct ftrace_ops trace_ops __read_mostly =
  {
  	.func = wakeup_tracer_call,
  };

  #endif /* CONFIG_FUNCTION_TRACER */

  
  static int start_func_tracer(int graph)
  {
  	int ret;
  
  	if (!graph)
  		ret = register_ftrace_function(&trace_ops);
  	else
  		ret = register_ftrace_graph(&wakeup_graph_return,
  					    &wakeup_graph_entry);
  
  	if (!ret && tracing_is_enabled())
  		tracer_enabled = 1;
  	else
  		tracer_enabled = 0;
  
  	return ret;
  }
  
  static void stop_func_tracer(int graph)
  {
  	tracer_enabled = 0;
  
  	if (!graph)
  		unregister_ftrace_function(&trace_ops);
  	else
  		unregister_ftrace_graph();
  }

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
  {
  
  	if (!(bit & TRACE_DISPLAY_GRAPH))
  		return -EINVAL;
  
  	if (!(is_graph() ^ set))
  		return 0;
  
  	stop_func_tracer(!set);
  
  	wakeup_reset(wakeup_trace);
  	tracing_max_latency = 0;
  
  	return start_func_tracer(set);
  }
  
  static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
  {
  	struct trace_array *tr = wakeup_trace;
  	struct trace_array_cpu *data;
  	unsigned long flags;

  	int pc, ret = 0;

  	if (!func_prolog_preempt_disable(tr, &data, &pc))

  		return 0;

  	local_save_flags(flags);
  	ret = __trace_graph_entry(tr, trace, flags, pc);

  	atomic_dec(&data->disabled);

  	preempt_enable_notrace();

  	return ret;
  }
  
  static void wakeup_graph_return(struct ftrace_graph_ret *trace)
  {
  	struct trace_array *tr = wakeup_trace;
  	struct trace_array_cpu *data;
  	unsigned long flags;

  	int pc;

  	if (!func_prolog_preempt_disable(tr, &data, &pc))

  		return;

  	local_save_flags(flags);
  	__trace_graph_return(tr, trace, flags, pc);

  	atomic_dec(&data->disabled);

  	preempt_enable_notrace();
  	return;
  }
  
  static void wakeup_trace_open(struct trace_iterator *iter)
  {
  	if (is_graph())
  		graph_trace_open(iter);
  }
  
  static void wakeup_trace_close(struct trace_iterator *iter)
  {
  	if (iter->private)
  		graph_trace_close(iter);
  }
  
  #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC)
  
  static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
  {
  	/*
  	 * In graph mode call the graph tracer output function,
  	 * otherwise go with the TRACE_FN event handler
  	 */
  	if (is_graph())
  		return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
  
  	return TRACE_TYPE_UNHANDLED;
  }
  
  static void wakeup_print_header(struct seq_file *s)
  {
  	if (is_graph())
  		print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
  	else
  		trace_default_header(s);
  }
  
  static void
  __trace_function(struct trace_array *tr,
  		 unsigned long ip, unsigned long parent_ip,
  		 unsigned long flags, int pc)
  {
  	if (is_graph())
  		trace_graph_function(tr, ip, parent_ip, flags, pc);
  	else
  		trace_function(tr, ip, parent_ip, flags, pc);
  }
  #else
  #define __trace_function trace_function
  
  static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
  {
  	return -EINVAL;
  }
  
  static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
  {
  	return -1;
  }
  
  static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
  {
  	return TRACE_TYPE_UNHANDLED;
  }
  
  static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
  static void wakeup_print_header(struct seq_file *s) { }
  static void wakeup_trace_open(struct trace_iterator *iter) { }
  static void wakeup_trace_close(struct trace_iterator *iter) { }
  #endif /* CONFIG_FUNCTION_GRAPH_TRACER */

  /*
   * 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
  probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)

  {
  	if (task != wakeup_task)
  		return;
  
  	wakeup_current_cpu = cpu;
  }

  static void notrace

  probe_wakeup_sched_switch(void *ignore,
  			  struct task_struct *prev, struct task_struct *next)

  {

  	struct trace_array_cpu *data;
  	cycle_t T0, T1, delta;
  	unsigned long flags;
  	long disabled;
  	int cpu;

  	int pc;

  	tracing_record_cmdline(prev);

  	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;

  	pc = preempt_count();

  	/* disable local data, not wakeup_cpu data */
  	cpu = raw_smp_processor_id();

  	disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);

  	if (likely(disabled != 1))
  		goto out;

  	local_irq_save(flags);

  	arch_spin_lock(&wakeup_lock);

  
  	/* We could race with grabbing wakeup_lock */
  	if (unlikely(!tracer_enabled || next != wakeup_task))
  		goto out_unlock;

  	/* The task we are waiting for is waking up */
  	data = wakeup_trace->data[wakeup_cpu];

  	__trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);

  	tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);

  	T0 = data->preempt_timestamp;

  	T1 = ftrace_now(cpu);

  	delta = T1-T0;
  
  	if (!report_latency(delta))
  		goto out_unlock;

  	if (likely(!is_tracing_stopped())) {
  		tracing_max_latency = delta;
  		update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
  	}

  out_unlock:

  	__wakeup_reset(wakeup_trace);

  	arch_spin_unlock(&wakeup_lock);

  	local_irq_restore(flags);

  out:

  	atomic_dec(&wakeup_trace->data[cpu]->disabled);

  }

  static void __wakeup_reset(struct trace_array *tr)

  {

  	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;

  	tracing_reset_online_cpus(tr);

  	local_irq_save(flags);

  	arch_spin_lock(&wakeup_lock);

  	__wakeup_reset(tr);

  	arch_spin_unlock(&wakeup_lock);

  	local_irq_restore(flags);

  }

  static void

  probe_wakeup(void *ignore, struct task_struct *p, int success)

  {

  	struct trace_array_cpu *data;

  	int cpu = smp_processor_id();
  	unsigned long flags;
  	long disabled;

  	int pc;

  	if (likely(!tracer_enabled))
  		return;
  
  	tracing_record_cmdline(p);
  	tracing_record_cmdline(current);

  	if ((wakeup_rt && !rt_task(p)) ||

  			p->prio >= wakeup_prio ||

  			p->prio >= current->prio)

  		return;

  	pc = preempt_count();

  	disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);

  	if (unlikely(disabled != 1))
  		goto out;
  
  	/* interrupts should be off from try_to_wake_up */

  	arch_spin_lock(&wakeup_lock);

  
  	/* check for races. */
  	if (!tracer_enabled || p->prio >= wakeup_prio)
  		goto out_locked;
  
  	/* reset the trace */

  	__wakeup_reset(wakeup_trace);

  
  	wakeup_cpu = task_cpu(p);

  	wakeup_current_cpu = wakeup_cpu;

  	wakeup_prio = p->prio;
  
  	wakeup_task = p;
  	get_task_struct(wakeup_task);
  
  	local_save_flags(flags);

  	data = wakeup_trace->data[wakeup_cpu];
  	data->preempt_timestamp = ftrace_now(cpu);

  	tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);

  
  	/*
  	 * We must be careful in using CALLER_ADDR2. But since wake_up
  	 * is not called by an assembly function  (where as schedule is)
  	 * it should be safe to use it here.
  	 */

  	__trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);

  
  out_locked:

  	arch_spin_unlock(&wakeup_lock);

  out:

  	atomic_dec(&wakeup_trace->data[cpu]->disabled);

  }

  static void start_wakeup_tracer(struct trace_array *tr)

  {

  	int ret;

  	ret = register_trace_sched_wakeup(probe_wakeup, NULL);

  	if (ret) {

  		pr_info("wakeup trace: Couldn't activate tracepoint"

  			" probe to kernel_sched_wakeup
  ");
  		return;
  	}

  	ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);

  	if (ret) {

  		pr_info("wakeup trace: Couldn't activate tracepoint"

  			" probe to kernel_sched_wakeup_new
  ");
  		goto fail_deprobe;
  	}

  	ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);

  	if (ret) {

  		pr_info("sched trace: Couldn't activate tracepoint"

  			" probe to kernel_sched_switch
  ");

  		goto fail_deprobe_wake_new;
  	}

  	ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);

  	if (ret) {
  		pr_info("wakeup trace: Couldn't activate tracepoint"
  			" probe to kernel_sched_migrate_task
  ");
  		return;
  	}

  	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();

  	if (start_func_tracer(is_graph()))
  		printk(KERN_ERR "failed to start wakeup tracer
  ");

  	return;

  fail_deprobe_wake_new:

  	unregister_trace_sched_wakeup_new(probe_wakeup, NULL);

  fail_deprobe:

  	unregister_trace_sched_wakeup(probe_wakeup, NULL);

  }

  static void stop_wakeup_tracer(struct trace_array *tr)

  {
  	tracer_enabled = 0;

  	stop_func_tracer(is_graph());

  	unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
  	unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
  	unregister_trace_sched_wakeup(probe_wakeup, NULL);
  	unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);

  }

  static int __wakeup_tracer_init(struct trace_array *tr)

  {

  	save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
  	trace_flags |= TRACE_ITER_LATENCY_FMT;

  	tracing_max_latency = 0;

  	wakeup_trace = tr;

  	start_wakeup_tracer(tr);

  	return 0;

  }

  static int wakeup_tracer_init(struct trace_array *tr)
  {
  	wakeup_rt = 0;
  	return __wakeup_tracer_init(tr);
  }
  
  static int wakeup_rt_tracer_init(struct trace_array *tr)
  {
  	wakeup_rt = 1;
  	return __wakeup_tracer_init(tr);
  }

  static void wakeup_tracer_reset(struct trace_array *tr)

  {

  	stop_wakeup_tracer(tr);
  	/* make sure we put back any tasks we are tracing */
  	wakeup_reset(tr);

  
  	if (!save_lat_flag)
  		trace_flags &= ~TRACE_ITER_LATENCY_FMT;

  }

  static void wakeup_tracer_start(struct trace_array *tr)
  {
  	wakeup_reset(tr);
  	tracer_enabled = 1;

  }
  
  static void wakeup_tracer_stop(struct trace_array *tr)
  {
  	tracer_enabled = 0;

  }
  
  static struct tracer wakeup_tracer __read_mostly =
  {
  	.name		= "wakeup",
  	.init		= wakeup_tracer_init,
  	.reset		= wakeup_tracer_reset,

  	.start		= wakeup_tracer_start,
  	.stop		= wakeup_tracer_stop,

  	.print_max	= 1,

  	.print_header	= wakeup_print_header,
  	.print_line	= wakeup_print_line,
  	.flags		= &tracer_flags,
  	.set_flag	= wakeup_set_flag,

  #ifdef CONFIG_FTRACE_SELFTEST
  	.selftest    = trace_selftest_startup_wakeup,
  #endif

  	.open		= wakeup_trace_open,
  	.close		= wakeup_trace_close,

  	.use_max_tr	= 1,

  };

  static struct tracer wakeup_rt_tracer __read_mostly =
  {
  	.name		= "wakeup_rt",
  	.init		= wakeup_rt_tracer_init,
  	.reset		= wakeup_tracer_reset,
  	.start		= wakeup_tracer_start,
  	.stop		= wakeup_tracer_stop,

  	.wait_pipe	= poll_wait_pipe,

  	.print_max	= 1,

  	.print_header	= wakeup_print_header,
  	.print_line	= wakeup_print_line,
  	.flags		= &tracer_flags,
  	.set_flag	= wakeup_set_flag,

  #ifdef CONFIG_FTRACE_SELFTEST
  	.selftest    = trace_selftest_startup_wakeup,
  #endif

  	.open		= wakeup_trace_open,
  	.close		= wakeup_trace_close,

  	.use_max_tr	= 1,

  };

  __init static int init_wakeup_tracer(void)
  {
  	int ret;
  
  	ret = register_tracer(&wakeup_tracer);
  	if (ret)
  		return ret;

  	ret = register_tracer(&wakeup_rt_tracer);
  	if (ret)
  		return ret;

  	return 0;
  }
  device_initcall(init_wakeup_tracer);