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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/marker.h>
#include <linux/ftrace.h>
#include "trace.h"
static struct trace_array *ctx_trace;
static int __read_mostly tracer_enabled;
static void notrace
ctx_switch_func(struct task_struct *prev, struct task_struct *next)
{
struct trace_array *tr = ctx_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
if (!tracer_enabled)
return;
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
tracing_sched_switch_trace(tr, data, prev, next, flags);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
void ftrace_ctx_switch(struct task_struct *prev, struct task_struct *next)
{
tracing_record_cmdline(prev);
/*
* If tracer_switch_func only points to the local
* switch func, it still needs the ptr passed to it.
*/
ctx_switch_func(prev, next);
/*
* Chain to the wakeup tracer (this is a NOP if disabled):
*/
wakeup_sched_switch(prev, next);
}
static notrace 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->data[cpu]);
}
static notrace void start_sched_trace(struct trace_array *tr)
{
sched_switch_reset(tr);
tracer_enabled = 1;
}
static notrace void stop_sched_trace(struct trace_array *tr)
{
tracer_enabled = 0;
}
static notrace void sched_switch_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
if (tr->ctrl)
start_sched_trace(tr);
}
static notrace 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)
{
return register_tracer(&sched_switch_trace);
}
device_initcall(init_sched_switch_trace);
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