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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * nop tracer
4 *
5 * Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net>
6 *
7 */
8
9#include <linux/module.h>
10#include <linux/ftrace.h>
11
12#include "trace.h"
13
14/* Our two options */
15enum {
16 TRACE_NOP_OPT_ACCEPT = 0x1,
17 TRACE_NOP_OPT_REFUSE = 0x2
18};
19
20/* Options for the tracer (see trace_options file) */
21static struct tracer_opt nop_opts[] = {
22 /* Option that will be accepted by set_flag callback */
23 { TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
24 /* Option that will be refused by set_flag callback */
25 { TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
26 { } /* Always set a last empty entry */
27};
28
29static struct tracer_flags nop_flags = {
30 /* You can check your flags value here when you want. */
31 .val = 0, /* By default: all flags disabled */
32 .opts = nop_opts
33};
34
35static struct trace_array *ctx_trace;
36
37static void start_nop_trace(struct trace_array *tr)
38{
39 /* Nothing to do! */
40}
41
42static void stop_nop_trace(struct trace_array *tr)
43{
44 /* Nothing to do! */
45}
46
47static int nop_trace_init(struct trace_array *tr)
48{
49 ctx_trace = tr;
50 start_nop_trace(tr);
51 return 0;
52}
53
54static void nop_trace_reset(struct trace_array *tr)
55{
56 stop_nop_trace(tr);
57}
58
59/* It only serves as a signal handler and a callback to
60 * accept or refuse the setting of a flag.
61 * If you don't implement it, then the flag setting will be
62 * automatically accepted.
63 */
64static int nop_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
65{
66 /*
67 * Note that you don't need to update nop_flags.val yourself.
68 * The tracing Api will do it automatically if you return 0
69 */
70 if (bit == TRACE_NOP_OPT_ACCEPT) {
71 printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
72 " Now cat trace_options to see the result\n",
73 set);
74 return 0;
75 }
76
77 if (bit == TRACE_NOP_OPT_REFUSE) {
78 printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
79 " Now cat trace_options to see the result\n",
80 set);
81 return -EINVAL;
82 }
83
84 return 0;
85}
86
87
88struct tracer nop_trace __read_mostly =
89{
90 .name = "nop",
91 .init = nop_trace_init,
92 .reset = nop_trace_reset,
93#ifdef CONFIG_FTRACE_SELFTEST
94 .selftest = trace_selftest_startup_nop,
95#endif
96 .flags = &nop_flags,
97 .set_flag = nop_set_flag,
98 .allow_instances = true,
99};
100
1/*
2 * nop tracer
3 *
4 * Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net>
5 *
6 */
7
8#include <linux/module.h>
9#include <linux/ftrace.h>
10
11#include "trace.h"
12
13/* Our two options */
14enum {
15 TRACE_NOP_OPT_ACCEPT = 0x1,
16 TRACE_NOP_OPT_REFUSE = 0x2
17};
18
19/* Options for the tracer (see trace_options file) */
20static struct tracer_opt nop_opts[] = {
21 /* Option that will be accepted by set_flag callback */
22 { TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
23 /* Option that will be refused by set_flag callback */
24 { TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
25 { } /* Always set a last empty entry */
26};
27
28static struct tracer_flags nop_flags = {
29 /* You can check your flags value here when you want. */
30 .val = 0, /* By default: all flags disabled */
31 .opts = nop_opts
32};
33
34static struct trace_array *ctx_trace;
35
36static void start_nop_trace(struct trace_array *tr)
37{
38 /* Nothing to do! */
39}
40
41static void stop_nop_trace(struct trace_array *tr)
42{
43 /* Nothing to do! */
44}
45
46static int nop_trace_init(struct trace_array *tr)
47{
48 ctx_trace = tr;
49 start_nop_trace(tr);
50 return 0;
51}
52
53static void nop_trace_reset(struct trace_array *tr)
54{
55 stop_nop_trace(tr);
56}
57
58/* It only serves as a signal handler and a callback to
59 * accept or refuse the setting of a flag.
60 * If you don't implement it, then the flag setting will be
61 * automatically accepted.
62 */
63static int nop_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
64{
65 /*
66 * Note that you don't need to update nop_flags.val yourself.
67 * The tracing Api will do it automatically if you return 0
68 */
69 if (bit == TRACE_NOP_OPT_ACCEPT) {
70 printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
71 " Now cat trace_options to see the result\n",
72 set);
73 return 0;
74 }
75
76 if (bit == TRACE_NOP_OPT_REFUSE) {
77 printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
78 " Now cat trace_options to see the result\n",
79 set);
80 return -EINVAL;
81 }
82
83 return 0;
84}
85
86
87struct tracer nop_trace __read_mostly =
88{
89 .name = "nop",
90 .init = nop_trace_init,
91 .reset = nop_trace_reset,
92#ifdef CONFIG_FTRACE_SELFTEST
93 .selftest = trace_selftest_startup_nop,
94#endif
95 .flags = &nop_flags,
96 .set_flag = nop_set_flag,
97 .allow_instances = true,
98};
99