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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
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/fs.h>
10#include <linux/debugfs.h>
11#include <linux/ftrace.h>
12
13#include "trace.h"
14
15/* Our two options */
16enum {
17 TRACE_NOP_OPT_ACCEPT = 0x1,
18 TRACE_NOP_OPT_REFUSE = 0x2
19};
20
21/* Options for the tracer (see trace_options file) */
22static struct tracer_opt nop_opts[] = {
23 /* Option that will be accepted by set_flag callback */
24 { TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) },
25 /* Option that will be refused by set_flag callback */
26 { TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) },
27 { } /* Always set a last empty entry */
28};
29
30static struct tracer_flags nop_flags = {
31 /* You can check your flags value here when you want. */
32 .val = 0, /* By default: all flags disabled */
33 .opts = nop_opts
34};
35
36static struct trace_array *ctx_trace;
37
38static void start_nop_trace(struct trace_array *tr)
39{
40 /* Nothing to do! */
41}
42
43static void stop_nop_trace(struct trace_array *tr)
44{
45 /* Nothing to do! */
46}
47
48static int nop_trace_init(struct trace_array *tr)
49{
50 ctx_trace = tr;
51 start_nop_trace(tr);
52 return 0;
53}
54
55static void nop_trace_reset(struct trace_array *tr)
56{
57 stop_nop_trace(tr);
58}
59
60/* It only serves as a signal handler and a callback to
61 * accept or refuse tthe setting of a flag.
62 * If you don't implement it, then the flag setting will be
63 * automatically accepted.
64 */
65static int nop_set_flag(u32 old_flags, u32 bit, int set)
66{
67 /*
68 * Note that you don't need to update nop_flags.val yourself.
69 * The tracing Api will do it automatically if you return 0
70 */
71 if (bit == TRACE_NOP_OPT_ACCEPT) {
72 printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept."
73 " Now cat trace_options to see the result\n",
74 set);
75 return 0;
76 }
77
78 if (bit == TRACE_NOP_OPT_REFUSE) {
79 printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse."
80 "Now cat trace_options to see the result\n",
81 set);
82 return -EINVAL;
83 }
84
85 return 0;
86}
87
88
89struct tracer nop_trace __read_mostly =
90{
91 .name = "nop",
92 .init = nop_trace_init,
93 .reset = nop_trace_reset,
94 .wait_pipe = poll_wait_pipe,
95#ifdef CONFIG_FTRACE_SELFTEST
96 .selftest = trace_selftest_startup_nop,
97#endif
98 .flags = &nop_flags,
99 .set_flag = nop_set_flag
100};
101