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Steven Rostedt9cfe06f2009-04-14 21:37:03 -04001/*
Steven Rostedt9cfe06f2009-04-14 21:37:03 -04002 * If TRACE_SYSTEM is defined, that will be the directory created
GeunSik Lim088a4ee2009-09-07 21:37:37 +09003 * in the ftrace directory under /sys/kernel/debug/tracing/events/<system>
Steven Rostedt9cfe06f2009-04-14 21:37:03 -04004 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -04005 * The define_trace.h below will also look for a file name of
Steven Rostedt9cfe06f2009-04-14 21:37:03 -04006 * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here.
Steven Rostedt44ad18e2009-06-16 19:53:07 -04007 * In this case, it would look for sample.h
Steven Rostedt9cfe06f2009-04-14 21:37:03 -04008 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -04009 * If the header name will be different than the system name
10 * (as in this case), then you can override the header name that
11 * define_trace.h will look up by defining TRACE_INCLUDE_FILE
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040012 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -040013 * This file is called trace-events-sample.h but we want the system
14 * to be called "sample". Therefore we must define the name of this
15 * file:
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040016 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -040017 * #define TRACE_INCLUDE_FILE trace-events-sample
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040018 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -040019 * As we do an the bottom of this file.
Li Zefand0b6e042009-07-13 10:33:21 +080020 *
21 * Notice that TRACE_SYSTEM should be defined outside of #if
22 * protection, just like TRACE_INCLUDE_FILE.
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040023 */
24#undef TRACE_SYSTEM
Steven Rostedt71e1c8a2009-05-06 21:20:39 -040025#define TRACE_SYSTEM sample
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040026
27/*
Li Zefand0b6e042009-07-13 10:33:21 +080028 * Notice that this file is not protected like a normal header.
29 * We also must allow for rereading of this file. The
30 *
31 * || defined(TRACE_HEADER_MULTI_READ)
32 *
33 * serves this purpose.
34 */
35#if !defined(_TRACE_EVENT_SAMPLE_H) || defined(TRACE_HEADER_MULTI_READ)
36#define _TRACE_EVENT_SAMPLE_H
37
38/*
39 * All trace headers should include tracepoint.h, until we finally
40 * make it into a standard header.
41 */
42#include <linux/tracepoint.h>
43
44/*
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040045 * The TRACE_EVENT macro is broken up into 5 parts.
46 *
47 * name: name of the trace point. This is also how to enable the tracepoint.
48 * A function called trace_foo_bar() will be created.
49 *
50 * proto: the prototype of the function trace_foo_bar()
51 * Here it is trace_foo_bar(char *foo, int bar).
52 *
53 * args: must match the arguments in the prototype.
54 * Here it is simply "foo, bar".
55 *
56 * struct: This defines the way the data will be stored in the ring buffer.
57 * There are currently two types of elements. __field and __array.
58 * a __field is broken up into (type, name). Where type can be any
Steven Rostedt4d4c9cc2014-06-17 08:59:16 -040059 * primitive type (integer, long or pointer). __field_struct() can
60 * be any static complex data value (struct, union, but not an array).
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040061 * For an array. there are three fields. (type, name, size). The
62 * type of elements in the array, the name of the field and the size
63 * of the array.
64 *
65 * __array( char, foo, 10) is the same as saying char foo[10].
66 *
67 * fast_assign: This is a C like function that is used to store the items
68 * into the ring buffer.
69 *
70 * printk: This is a way to print out the data in pretty print. This is
71 * useful if the system crashes and you are logging via a serial line,
72 * the data can be printed to the console using this "printk" method.
73 *
74 * Note, that for both the assign and the printk, __entry is the handler
75 * to the data structure in the ring buffer, and is defined by the
76 * TP_STRUCT__entry.
77 */
78TRACE_EVENT(foo_bar,
79
80 TP_PROTO(char *foo, int bar),
81
82 TP_ARGS(foo, bar),
83
84 TP_STRUCT__entry(
85 __array( char, foo, 10 )
86 __field( int, bar )
87 ),
88
89 TP_fast_assign(
Zhao Hongjiangd8fae2f2013-06-20 19:05:40 +080090 strlcpy(__entry->foo, foo, 10);
Steven Rostedt9cfe06f2009-04-14 21:37:03 -040091 __entry->bar = bar;
92 ),
93
94 TP_printk("foo %s %d", __entry->foo, __entry->bar)
95);
96#endif
97
98/***** NOTICE! The #if protection ends here. *****/
99
100
101/*
102 * There are several ways I could have done this. If I left out the
103 * TRACE_INCLUDE_PATH, then it would default to the kernel source
104 * include/trace/events directory.
105 *
106 * I could specify a path from the define_trace.h file back to this
107 * file.
108 *
109 * #define TRACE_INCLUDE_PATH ../../samples/trace_events
110 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -0400111 * But the safest and easiest way to simply make it use the directory
112 * that the file is in is to add in the Makefile:
Steven Rostedt9cfe06f2009-04-14 21:37:03 -0400113 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -0400114 * CFLAGS_trace-events-sample.o := -I$(src)
Steven Rostedt9cfe06f2009-04-14 21:37:03 -0400115 *
116 * This will make sure the current path is part of the include
Steven Rostedt44ad18e2009-06-16 19:53:07 -0400117 * structure for our file so that define_trace.h can find it.
Steven Rostedt9cfe06f2009-04-14 21:37:03 -0400118 *
119 * I could have made only the top level directory the include:
120 *
121 * CFLAGS_trace-events-sample.o := -I$(PWD)
122 *
123 * And then let the path to this directory be the TRACE_INCLUDE_PATH:
124 *
125 * #define TRACE_INCLUDE_PATH samples/trace_events
126 *
Steven Rostedt44ad18e2009-06-16 19:53:07 -0400127 * But then if something defines "samples" or "trace_events" as a macro
128 * then we could risk that being converted too, and give us an unexpected
Steven Rostedt9cfe06f2009-04-14 21:37:03 -0400129 * result.
130 */
131#undef TRACE_INCLUDE_PATH
Steven Rostedt71e1c8a2009-05-06 21:20:39 -0400132#undef TRACE_INCLUDE_FILE
Steven Rostedt9cfe06f2009-04-14 21:37:03 -0400133#define TRACE_INCLUDE_PATH .
Steven Rostedt71e1c8a2009-05-06 21:20:39 -0400134/*
135 * TRACE_INCLUDE_FILE is not needed if the filename and TRACE_SYSTEM are equal
136 */
137#define TRACE_INCLUDE_FILE trace-events-sample
Steven Rostedt9cfe06f2009-04-14 21:37:03 -0400138#include <trace/define_trace.h>