/*
 * 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(struct rq *__rq, 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(struct rq *__rq, 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);
        if (ret) {
                pr_info("wakeup trace: Couldn't activate tracepoint"
                        " probe to kernel_sched_wakeup\n");
                return ret;
        }

        ret = register_trace_sched_wakeup_new(probe_sched_wakeup);
        if (ret) {
                pr_info("wakeup trace: Couldn't activate tracepoint"
                        " probe to kernel_sched_wakeup_new\n");
                goto fail_deprobe;
        }

        ret = register_trace_sched_switch(probe_sched_switch);
        if (ret) {
                pr_info("sched trace: Couldn't activate tracepoint"
                        " probe to kernel_sched_switch\n");
                goto fail_deprobe_wake_new;
        }

        return ret;
fail_deprobe_wake_new:
        unregister_trace_sched_wakeup_new(probe_sched_wakeup);
fail_deprobe:
        unregister_trace_sched_wakeup(probe_sched_wakeup);
        return ret;
}

static void tracing_sched_unregister(void)
{
        unregister_trace_sched_switch(probe_sched_switch);
        unregister_trace_sched_wakeup_new(probe_sched_wakeup);
        unregister_trace_sched_wakeup(probe_sched_wakeup);
}

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;
}

static void stop_sched_trace(struct trace_array *tr)
{
        tracing_stop_sched_switch_record();
}

static int sched_switch_trace_init(struct trace_array *tr)
{
        ctx_trace = tr;
        tracing_reset_online_cpus(tr);
        tracing_start_sched_switch_record();
        return 0;
}

static void sched_switch_trace_reset(struct trace_array *tr)
{
        if (sched_ref)
                stop_sched_trace(tr);
}

static void sched_switch_trace_start(struct trace_array *tr)
{
        sched_stopped = 0;
}

static void sched_switch_trace_stop(struct trace_array *tr)
{
        sched_stopped = 1;
}

static struct tracer sched_switch_trace __read_mostly =
{
        .name           = "sched_switch",
        .init           = sched_switch_trace_init,
        .reset          = sched_switch_trace_reset,
        .start          = sched_switch_trace_start,
        .stop           = sched_switch_trace_stop,
        .wait_pipe      = poll_wait_pipe,
#ifdef CONFIG_FTRACE_SELFTEST
        .selftest    = trace_selftest_startup_sched_switch,
#endif
};

__init static int init_sched_switch_trace(void)
{
        return register_tracer(&sched_switch_trace);
}
device_initcall(init_sched_switch_trace);