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/*
* 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/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;
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 (!sched_ref || sched_stopped)
return;
tracing_record_cmdline(prev);
tracing_record_cmdline(next);
if (!tracer_enabled)
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);
}
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 (!likely(tracer_enabled))
return;
pc = preempt_count();
tracing_record_cmdline(current);
if (sched_stopped)
return;
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);
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