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fb1b6d8b SN |
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 | ||
0619faf6 FW |
15 | /* Our two options */ |
16 | enum { | |
17 | TRACE_NOP_OPT_ACCEPT = 0x1, | |
18 | TRACE_NOP_OPT_REFUSE = 0x2 | |
19 | }; | |
20 | ||
21 | /* Options for the tracer (see trace_options file) */ | |
22 | static 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 | ||
30 | static 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 | ||
fb1b6d8b SN |
36 | static struct trace_array *ctx_trace; |
37 | ||
38 | static void start_nop_trace(struct trace_array *tr) | |
39 | { | |
40 | /* Nothing to do! */ | |
41 | } | |
42 | ||
43 | static void stop_nop_trace(struct trace_array *tr) | |
44 | { | |
45 | /* Nothing to do! */ | |
46 | } | |
47 | ||
1c80025a | 48 | static int nop_trace_init(struct trace_array *tr) |
fb1b6d8b | 49 | { |
35cb5ed0 | 50 | int cpu; |
fb1b6d8b SN |
51 | ctx_trace = tr; |
52 | ||
35cb5ed0 | 53 | for_each_online_cpu(cpu) |
3928a8a2 | 54 | tracing_reset(tr, cpu); |
35cb5ed0 | 55 | |
c76f0694 | 56 | start_nop_trace(tr); |
1c80025a | 57 | return 0; |
fb1b6d8b SN |
58 | } |
59 | ||
60 | static void nop_trace_reset(struct trace_array *tr) | |
61 | { | |
c76f0694 | 62 | stop_nop_trace(tr); |
fb1b6d8b SN |
63 | } |
64 | ||
0619faf6 FW |
65 | /* It only serves as a signal handler and a callback to |
66 | * accept or refuse tthe setting of a flag. | |
67 | * If you don't implement it, then the flag setting will be | |
68 | * automatically accepted. | |
69 | */ | |
70 | static int nop_set_flag(u32 old_flags, u32 bit, int set) | |
71 | { | |
72 | /* | |
73 | * Note that you don't need to update nop_flags.val yourself. | |
74 | * The tracing Api will do it automatically if you return 0 | |
75 | */ | |
76 | if (bit == TRACE_NOP_OPT_ACCEPT) { | |
77 | printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept." | |
78 | " Now cat trace_options to see the result\n", | |
79 | set); | |
80 | return 0; | |
81 | } | |
82 | ||
83 | if (bit == TRACE_NOP_OPT_REFUSE) { | |
84 | printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse." | |
85 | "Now cat trace_options to see the result\n", | |
86 | set); | |
87 | return -EINVAL; | |
88 | } | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | ||
43a15386 | 94 | struct tracer nop_trace __read_mostly = |
fb1b6d8b SN |
95 | { |
96 | .name = "nop", | |
97 | .init = nop_trace_init, | |
98 | .reset = nop_trace_reset, | |
fb1b6d8b SN |
99 | #ifdef CONFIG_FTRACE_SELFTEST |
100 | .selftest = trace_selftest_startup_nop, | |
101 | #endif | |
0619faf6 FW |
102 | .flags = &nop_flags, |
103 | .set_flag = nop_set_flag | |
fb1b6d8b SN |
104 | }; |
105 |