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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 atomic_t sched_ref;
static void
probe_sched_switch(struct rq *__rq, struct task_struct *prev,
struct task_struct *next)
{
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
if (!atomic_read(&sched_ref))
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];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static void
probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
{
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu, pc;
if (!likely(tracer_enabled))
return;
pc = preempt_count();
tracing_record_cmdline(current);
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = ctx_trace->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
flags, pc);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
static void sched_switch_reset(struct trace_array *tr)
{
int cpu;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
}
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_schedule\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)
{
long ref;
ref = atomic_inc_return(&sched_ref);
if (ref == 1)
tracing_sched_register();
}
static void tracing_stop_sched_switch(void)
{
long ref;
ref = atomic_dec_and_test(&sched_ref);
if (ref)
tracing_sched_unregister();
}
void tracing_start_cmdline_record(void)
{
tracing_start_sched_switch();
}
void tracing_stop_cmdline_record(void)
{
tracing_stop_sched_switch();
}
static void start_sched_trace(struct trace_array *tr)
{
sched_switch_reset(tr);
tracing_start_cmdline_record();
tracer_enabled = 1;
}
static void stop_sched_trace(struct trace_array *tr)
{
tracer_enabled = 0;
tracing_stop_cmdline_record();
}
static void sched_switch_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
if (tr->ctrl)
start_sched_trace(tr);
}
static void sched_switch_trace_reset(struct trace_array *tr)
{
if (tr->ctrl)
stop_sched_trace(tr);
}
static void sched_switch_trace_ctrl_update(struct trace_array *tr)
{
/* When starting a new trace, reset the buffers */
if (tr->ctrl)
start_sched_trace(tr);
else
stop_sched_trace(tr);
}
static struct tracer sched_switch_trace __read_mostly =
{
.name = "sched_switch",
.init = sched_switch_trace_init,
.reset = sched_switch_trace_reset,
.ctrl_update = sched_switch_trace_ctrl_update,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_sched_switch,
#endif
};
__init static int init_sched_switch_trace(void)
{
int ret = 0;
if (atomic_read(&sched_ref))
ret = tracing_sched_register();
if (ret) {
pr_info("error registering scheduler trace\n");
return ret;
}
return register_tracer(&sched_switch_trace);
}
device_initcall(init_sched_switch_trace);
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