android_kernel_xiaomi_sm8350/kernel/trace/trace_nop.c
Frederic Weisbecker 1c80025a49 tracing/ftrace: change the type of the init() callback
Impact: extend the ->init() method with the ability to fail

This bring a way to know if the initialization of a tracer successed.
A tracer must return 0 on success and a traditional error (ie:
-ENOMEM) if it fails.

If a tracer fails to init, it is free to print a detailed warn. The
tracing api will not and switch to a new tracer will just return the
error from the init callback.

Note: this will be used for the return tracer.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-16 07:55:23 +01:00

54 lines
848 B
C

/*
* nop tracer
*
* Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net>
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/ftrace.h>
#include "trace.h"
static struct trace_array *ctx_trace;
static void start_nop_trace(struct trace_array *tr)
{
/* Nothing to do! */
}
static void stop_nop_trace(struct trace_array *tr)
{
/* Nothing to do! */
}
static int nop_trace_init(struct trace_array *tr)
{
int cpu;
ctx_trace = tr;
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
start_nop_trace(tr);
return 0;
}
static void nop_trace_reset(struct trace_array *tr)
{
stop_nop_trace(tr);
}
struct tracer nop_trace __read_mostly =
{
.name = "nop",
.init = nop_trace_init,
.reset = nop_trace_reset,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_nop,
#endif
};