mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 07:40:53 +07:00
0619faf657
Impact: give an example on how to use specific tracer flags
This patch propose to use the nop tracer to provide an
example for using the tracer's custom flags implementation.
V2: replace structures and defines just after the headers includes for
cleanliness.
V3: replace defines by enum values.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Noonan <steven@uplinklabs.net>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
106 lines
2.2 KiB
C
106 lines
2.2 KiB
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"
|
|
|
|
/* Our two options */
|
|
enum {
|
|
TRACE_NOP_OPT_ACCEPT = 0x1,
|
|
TRACE_NOP_OPT_REFUSE = 0x2
|
|
};
|
|
|
|
/* Options for the tracer (see trace_options file) */
|
|
static struct tracer_opt nop_opts[] = {
|
|
/* Option that will be accepted by set_flag callback */
|
|
{ TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
|
|
/* Option that will be refused by set_flag callback */
|
|
{ TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
|
|
{ } /* Always set a last empty entry */
|
|
};
|
|
|
|
static struct tracer_flags nop_flags = {
|
|
/* You can check your flags value here when you want. */
|
|
.val = 0, /* By default: all flags disabled */
|
|
.opts = nop_opts
|
|
};
|
|
|
|
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);
|
|
}
|
|
|
|
/* It only serves as a signal handler and a callback to
|
|
* accept or refuse tthe setting of a flag.
|
|
* If you don't implement it, then the flag setting will be
|
|
* automatically accepted.
|
|
*/
|
|
static int nop_set_flag(u32 old_flags, u32 bit, int set)
|
|
{
|
|
/*
|
|
* Note that you don't need to update nop_flags.val yourself.
|
|
* The tracing Api will do it automatically if you return 0
|
|
*/
|
|
if (bit == TRACE_NOP_OPT_ACCEPT) {
|
|
printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
|
|
" Now cat trace_options to see the result\n",
|
|
set);
|
|
return 0;
|
|
}
|
|
|
|
if (bit == TRACE_NOP_OPT_REFUSE) {
|
|
printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
|
|
"Now cat trace_options to see the result\n",
|
|
set);
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
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
|
|
.flags = &nop_flags,
|
|
.set_flag = nop_set_flag
|
|
};
|
|
|