7e9b42aeae0e1c8fc72d6bb21f1d2084cacf8889
[linux-2.6.git] / include / linux / tracepoint.h
1 #ifndef _LINUX_TRACEPOINT_H
2 #define _LINUX_TRACEPOINT_H
3
4 /*
5  * Kernel Tracepoint API.
6  *
7  * See Documentation/tracepoint.txt.
8  *
9  * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
10  *
11  * Heavily inspired from the Linux Kernel Markers.
12  *
13  * This file is released under the GPLv2.
14  * See the file COPYING for more details.
15  */
16
17 #include <linux/types.h>
18 #include <linux/rcupdate.h>
19
20 struct module;
21 struct tracepoint;
22
23 struct tracepoint {
24         const char *name;               /* Tracepoint name */
25         int state;                      /* State. */
26         void **funcs;
27 } __attribute__((aligned(8)));
28
29
30 #define TPPROTO(args...)        args
31 #define TPARGS(args...)         args
32
33 #ifdef CONFIG_TRACEPOINTS
34
35 /*
36  * it_func[0] is never NULL because there is at least one element in the array
37  * when the array itself is non NULL.
38  */
39 #define __DO_TRACE(tp, proto, args)                                     \
40         do {                                                            \
41                 void **it_func;                                         \
42                                                                         \
43                 rcu_read_lock_sched_notrace();                          \
44                 it_func = rcu_dereference((tp)->funcs);                 \
45                 if (it_func) {                                          \
46                         do {                                            \
47                                 ((void(*)(proto))(*it_func))(args);     \
48                         } while (*(++it_func));                         \
49                 }                                                       \
50                 rcu_read_unlock_sched_notrace();                        \
51         } while (0)
52
53 /*
54  * Make sure the alignment of the structure in the __tracepoints section will
55  * not add unwanted padding between the beginning of the section and the
56  * structure. Force alignment to the same alignment as the section start.
57  */
58 #define DEFINE_TRACE(name, proto, args)                                 \
59         static inline void trace_##name(proto)                          \
60         {                                                               \
61                 static const char __tpstrtab_##name[]                   \
62                 __attribute__((section("__tracepoints_strings")))       \
63                 = #name;                                                \
64                 static struct tracepoint __tracepoint_##name            \
65                 __attribute__((section("__tracepoints"), aligned(8))) = \
66                 { __tpstrtab_##name, 0, NULL };                         \
67                 if (unlikely(__tracepoint_##name.state))                \
68                         __DO_TRACE(&__tracepoint_##name,                \
69                                 TPPROTO(proto), TPARGS(args));          \
70         }                                                               \
71         static inline int register_trace_##name(void (*probe)(proto))   \
72         {                                                               \
73                 return tracepoint_probe_register(#name, (void *)probe); \
74         }                                                               \
75         static inline int unregister_trace_##name(void (*probe)(proto)) \
76         {                                                               \
77                 return tracepoint_probe_unregister(#name, (void *)probe);\
78         }
79
80 extern void tracepoint_update_probe_range(struct tracepoint *begin,
81         struct tracepoint *end);
82
83 #else /* !CONFIG_TRACEPOINTS */
84 #define DEFINE_TRACE(name, proto, args)                 \
85         static inline void _do_trace_##name(struct tracepoint *tp, proto) \
86         { }                                                             \
87         static inline void trace_##name(proto)                          \
88         { }                                                             \
89         static inline int register_trace_##name(void (*probe)(proto))   \
90         {                                                               \
91                 return -ENOSYS;                                         \
92         }                                                               \
93         static inline int unregister_trace_##name(void (*probe)(proto)) \
94         {                                                               \
95                 return -ENOSYS;                                         \
96         }
97
98 static inline void tracepoint_update_probe_range(struct tracepoint *begin,
99         struct tracepoint *end)
100 { }
101 #endif /* CONFIG_TRACEPOINTS */
102
103 /*
104  * Connect a probe to a tracepoint.
105  * Internal API, should not be used directly.
106  */
107 extern int tracepoint_probe_register(const char *name, void *probe);
108
109 /*
110  * Disconnect a probe from a tracepoint.
111  * Internal API, should not be used directly.
112  */
113 extern int tracepoint_probe_unregister(const char *name, void *probe);
114
115 extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
116 extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
117 extern void tracepoint_probe_update_all(void);
118
119 struct tracepoint_iter {
120         struct module *module;
121         struct tracepoint *tracepoint;
122 };
123
124 extern void tracepoint_iter_start(struct tracepoint_iter *iter);
125 extern void tracepoint_iter_next(struct tracepoint_iter *iter);
126 extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
127 extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
128 extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
129         struct tracepoint *begin, struct tracepoint *end);
130
131 /*
132  * tracepoint_synchronize_unregister must be called between the last tracepoint
133  * probe unregistration and the end of module exit to make sure there is no
134  * caller executing a probe when it is freed.
135  */
136 static inline void tracepoint_synchronize_unregister(void)
137 {
138         synchronize_sched();
139 }
140
141 #endif