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1 | /* probe-example.c |
2 | * |
3 | * Connects a two functions to marker call sites. |
4 | * |
5 | * (C) Copyright 2007 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> |
6 | * |
7 | * This file is released under the GPLv2. |
8 | * See the file COPYING for more details. |
9 | */ |
10 | |
11 | #include <linux/sched.h> |
12 | #include <linux/kernel.h> |
13 | #include <linux/module.h> |
14 | #include <linux/marker.h> |
15 | #include <asm/atomic.h> |
16 | |
17 | #define NUM_PROBES (sizeof(probe_array) / sizeof(struct probe_data)) |
18 | |
19 | struct probe_data { |
20 | const char *name; |
21 | const char *format; |
22 | marker_probe_func *probe_func; |
23 | }; |
24 | |
25 | void probe_subsystem_event(const struct __mark_marker_c *mdata, |
26 | const char *format, ...) |
27 | { |
28 | va_list ap; |
29 | /* Declare args */ |
30 | unsigned int value; |
31 | const char *mystr; |
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32 | |
33 | /* Assign args */ |
34 | va_start(ap, format); |
35 | value = va_arg(ap, typeof(value)); |
36 | mystr = va_arg(ap, typeof(mystr)); |
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37 | |
38 | /* Call printk */ |
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39 | printk("Value %u, string %s\n", value, mystr); |
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40 | |
41 | /* or count, check rights, serialize data in a buffer */ |
42 | |
43 | va_end(ap); |
44 | } |
45 | |
46 | atomic_t eventb_count = ATOMIC_INIT(0); |
47 | |
48 | void probe_subsystem_eventb(const struct __mark_marker_c *mdata, |
49 | const char *format, ...) |
50 | { |
51 | /* Increment counter */ |
52 | atomic_inc(&eventb_count); |
53 | } |
54 | |
55 | static struct probe_data probe_array[] = |
56 | { |
57 | { .name = "subsystem_event", |
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58 | .format = "%d %s", |
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59 | .probe_func = probe_subsystem_event }, |
60 | { .name = "subsystem_eventb", |
61 | .format = MARK_NOARGS, |
62 | .probe_func = probe_subsystem_eventb }, |
63 | }; |
64 | |
65 | static int __init probe_init(void) |
66 | { |
67 | int result; |
68 | uint8_t eID; |
69 | |
70 | for (eID = 0; eID < NUM_PROBES; eID++) { |
71 | result = marker_set_probe(probe_array[eID].name, |
72 | probe_array[eID].format, |
73 | probe_array[eID].probe_func, &probe_array[eID]); |
74 | if (!result) |
75 | printk(KERN_INFO "Unable to register probe %s\n", |
76 | probe_array[eID].name); |
77 | } |
78 | return 0; |
79 | } |
80 | |
81 | static void __exit probe_fini(void) |
82 | { |
83 | uint8_t eID; |
84 | |
85 | for (eID = 0; eID < NUM_PROBES; eID++) { |
86 | marker_remove_probe(probe_array[eID].name); |
87 | } |
88 | synchronize_sched(); /* Wait for probes to finish */ |
89 | printk("Number of event b : %u\n", atomic_read(&eventb_count)); |
90 | } |
91 | |
92 | module_init(probe_init); |
93 | module_exit(probe_fini); |
94 | |
95 | MODULE_LICENSE("GPL"); |
96 | MODULE_AUTHOR("Mathieu Desnoyers"); |
97 | MODULE_DESCRIPTION("SUBSYSTEM Probe"); |