/*
   * trace context switch
   *
   * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
   *
   */
  #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	*ctx_trace;
  static int __read_mostly	tracer_enabled;

  static int			sched_ref;
  static DEFINE_MUTEX(sched_register_mutex);

  static int			sched_stopped;

  
  void
  tracing_sched_switch_trace(struct trace_array *tr,
  			   struct task_struct *prev,
  			   struct task_struct *next,
  			   unsigned long flags, int pc)
  {
  	struct ftrace_event_call *call = &event_context_switch;

  	struct ring_buffer *buffer = tr->buffer;

  	struct ring_buffer_event *event;
  	struct ctx_switch_entry *entry;

  	event = trace_buffer_lock_reserve(buffer, TRACE_CTX,

  					  sizeof(*entry), flags, pc);
  	if (!event)
  		return;
  	entry	= ring_buffer_event_data(event);
  	entry->prev_pid			= prev->pid;
  	entry->prev_prio		= prev->prio;
  	entry->prev_state		= prev->state;
  	entry->next_pid			= next->pid;
  	entry->next_prio		= next->prio;
  	entry->next_state		= next->state;
  	entry->next_cpu	= task_cpu(next);

  	if (!filter_check_discard(call, entry, buffer, event))
  		trace_buffer_unlock_commit(buffer, event, flags, pc);

  }

  static void

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

  {

  	struct trace_array_cpu *data;
  	unsigned long flags;

  	int cpu;

  	int pc;

  	if (unlikely(!sched_ref))

  		return;

  	tracing_record_cmdline(prev);
  	tracing_record_cmdline(next);

  	if (!tracer_enabled || sched_stopped)

  		return;

  	pc = preempt_count();

  	local_irq_save(flags);

  	cpu = raw_smp_processor_id();

  	data = ctx_trace->data[cpu];

  	if (likely(!atomic_read(&data->disabled)))

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

  	local_irq_restore(flags);

  }

  void
  tracing_sched_wakeup_trace(struct trace_array *tr,
  			   struct task_struct *wakee,
  			   struct task_struct *curr,
  			   unsigned long flags, int pc)
  {
  	struct ftrace_event_call *call = &event_wakeup;
  	struct ring_buffer_event *event;
  	struct ctx_switch_entry *entry;

  	struct ring_buffer *buffer = tr->buffer;

  	event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,

  					  sizeof(*entry), flags, pc);
  	if (!event)
  		return;
  	entry	= ring_buffer_event_data(event);
  	entry->prev_pid			= curr->pid;
  	entry->prev_prio		= curr->prio;
  	entry->prev_state		= curr->state;
  	entry->next_pid			= wakee->pid;
  	entry->next_prio		= wakee->prio;
  	entry->next_state		= wakee->state;
  	entry->next_cpu			= task_cpu(wakee);

  	if (!filter_check_discard(call, entry, buffer, event))
  		ring_buffer_unlock_commit(buffer, event);
  	ftrace_trace_stack(tr->buffer, flags, 6, pc);
  	ftrace_trace_userstack(tr->buffer, flags, pc);

  }

  static void

  probe_sched_wakeup(void *ignore, struct task_struct *wakee, int success)

  {

  	struct trace_array_cpu *data;
  	unsigned long flags;

  	int cpu, pc;

  	if (unlikely(!sched_ref))

  		return;

  	tracing_record_cmdline(current);

  	if (!tracer_enabled || sched_stopped)

  		return;

  	pc = preempt_count();

  	local_irq_save(flags);
  	cpu = raw_smp_processor_id();

  	data = ctx_trace->data[cpu];

  	if (likely(!atomic_read(&data->disabled)))

  		tracing_sched_wakeup_trace(ctx_trace, wakee, current,

  					   flags, pc);

  	local_irq_restore(flags);
  }

  static int tracing_sched_register(void)
  {
  	int ret;

  	ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);

  	if (ret) {

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

  			" probe to kernel_sched_wakeup
  ");
  		return ret;
  	}

  	ret = register_trace_sched_wakeup_new(probe_sched_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_sched_switch, NULL);

  	if (ret) {

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

  			" probe to kernel_sched_switch
  ");

  		goto fail_deprobe_wake_new;
  	}
  
  	return ret;
  fail_deprobe_wake_new:

  	unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);

  fail_deprobe:

  	unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);

  	return ret;
  }
  
  static void tracing_sched_unregister(void)
  {

  	unregister_trace_sched_switch(probe_sched_switch, NULL);
  	unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  	unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);

  }

  static void tracing_start_sched_switch(void)

  {

  	mutex_lock(&sched_register_mutex);

  	if (!(sched_ref++))

  		tracing_sched_register();

  	mutex_unlock(&sched_register_mutex);

  }

  static void tracing_stop_sched_switch(void)

  {

  	mutex_lock(&sched_register_mutex);

  	if (!(--sched_ref))

  		tracing_sched_unregister();

  	mutex_unlock(&sched_register_mutex);

  }

  void tracing_start_cmdline_record(void)
  {
  	tracing_start_sched_switch();
  }
  
  void tracing_stop_cmdline_record(void)
  {
  	tracing_stop_sched_switch();
  }

  /**

   * tracing_start_sched_switch_record - start tracing context switches
   *
   * Turns on context switch tracing for a tracer.
   */
  void tracing_start_sched_switch_record(void)
  {
  	if (unlikely(!ctx_trace)) {
  		WARN_ON(1);
  		return;
  	}
  
  	tracing_start_sched_switch();
  
  	mutex_lock(&sched_register_mutex);
  	tracer_enabled++;
  	mutex_unlock(&sched_register_mutex);
  }
  
  /**
   * tracing_stop_sched_switch_record - start tracing context switches
   *
   * Turns off context switch tracing for a tracer.
   */
  void tracing_stop_sched_switch_record(void)
  {
  	mutex_lock(&sched_register_mutex);
  	tracer_enabled--;
  	WARN_ON(tracer_enabled < 0);
  	mutex_unlock(&sched_register_mutex);
  
  	tracing_stop_sched_switch();
  }
  
  /**
   * tracing_sched_switch_assign_trace - assign a trace array for ctx switch

   * @tr: trace array pointer to assign
   *
   * Some tracers might want to record the context switches in their
   * trace. This function lets those tracers assign the trace array
   * to use.
   */

  void tracing_sched_switch_assign_trace(struct trace_array *tr)

  {
  	ctx_trace = tr;
  }