lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

ftrace: add nop tracer

Browse Source 
A no-op tracer which can serve two purposes:

 1. A template for development of a new tracer.
 2. A convenient way to see ftrace_printk() calls without
    an irrelevant trace making the output messy.

[ mingo@elte.hu: resolved conflicts ]
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Noonan
2008-09-19 03:06:43 -07:00
committed by Ingo Molnar
parent 5bf9a1ee35
commit fb1b6d8b51
5 changed files with 89 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

65
kernel/trace/trace_nop.c Normal file
View File

@@ -0,0 +1,65 @@
/*
* 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 void nop_trace_init(struct trace_array *tr)
{
ctx_trace = tr;
if (tr->ctrl)
start_nop_trace(tr);
}
static void nop_trace_reset(struct trace_array *tr)
{
if (tr->ctrl)
stop_nop_trace(tr);
}
static void nop_trace_ctrl_update(struct trace_array *tr)
{
/* When starting a new trace, reset the buffers */
if (tr->ctrl)
start_nop_trace(tr);
else
stop_nop_trace(tr);
}
static struct tracer nop_trace __read_mostly =
{
.name = "nop",
.init = nop_trace_init,
.reset = nop_trace_reset,
.ctrl_update = nop_trace_ctrl_update,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_nop,
#endif
};
__init static int init_nop_trace(void)
{
return register_tracer(&nop_trace);
}
device_initcall(init_nop_trace);