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authorSteven Rostedt <srostedt@redhat.com>2009-06-16 19:53:07 -0400
committerSteven Rostedt <rostedt@goodmis.org>2009-06-16 19:53:07 -0400
commit44ad18e0a65e296b2e68a1452509f6222cdce743 (patch)
tree6828a8d5508ba9c93f8d094e78adead19d28aaa3 /samples
parent00e95830a4d6e49f764fdb19896a89199bc0aa3b (diff)
tracing: update sample event documentation
The comments in the sample code is a bit confusing. This patch cleans them up a little. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'samples')
-rw-r--r--samples/trace_events/Makefile8
-rw-r--r--samples/trace_events/trace-events-sample.h27
2 files changed, 24 insertions, 11 deletions
diff --git a/samples/trace_events/Makefile b/samples/trace_events/Makefile
index 0d428dc67283..0f8d92120c4e 100644
--- a/samples/trace_events/Makefile
+++ b/samples/trace_events/Makefile
@@ -1,6 +1,14 @@
1# builds the trace events example kernel modules; 1# builds the trace events example kernel modules;
2# then to use one (as root): insmod <module_name.ko> 2# then to use one (as root): insmod <module_name.ko>
3 3
4# If you include a trace header outside of include/trace/events
5# then the file that does the #define CREATE_TRACE_POINTS must
6# have that tracer file in its main search path. This is because
7# define_trace.h will include it, and must be able to find it from
8# the include/trace directory.
9#
10# Here trace-events-sample.c does the CREATE_TRACE_POINTS.
11#
4CFLAGS_trace-events-sample.o := -I$(src) 12CFLAGS_trace-events-sample.o := -I$(src)
5 13
6obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace-events-sample.o 14obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace-events-sample.o
diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h
index 128a897687c5..9977a756fb32 100644
--- a/samples/trace_events/trace-events-sample.h
+++ b/samples/trace_events/trace-events-sample.h
@@ -19,16 +19,21 @@
19 * If TRACE_SYSTEM is defined, that will be the directory created 19 * If TRACE_SYSTEM is defined, that will be the directory created
20 * in the ftrace directory under /debugfs/tracing/events/<system> 20 * in the ftrace directory under /debugfs/tracing/events/<system>
21 * 21 *
22 * The define_trace.h belowe will also look for a file name of 22 * The define_trace.h below will also look for a file name of
23 * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here. 23 * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here.
24 * In this case, it would look for sample.h
24 * 25 *
25 * If you want a different system than file name, you can override 26 * If the header name will be different than the system name
26 * the header name by defining TRACE_INCLUDE_FILE 27 * (as in this case), then you can override the header name that
28 * define_trace.h will look up by defining TRACE_INCLUDE_FILE
27 * 29 *
28 * If this file was called, goofy.h, then we would define: 30 * This file is called trace-events-sample.h but we want the system
31 * to be called "sample". Therefore we must define the name of this
32 * file:
29 * 33 *
30 * #define TRACE_INCLUDE_FILE goofy 34 * #define TRACE_INCLUDE_FILE trace-events-sample
31 * 35 *
36 * As we do an the bottom of this file.
32 */ 37 */
33#undef TRACE_SYSTEM 38#undef TRACE_SYSTEM
34#define TRACE_SYSTEM sample 39#define TRACE_SYSTEM sample
@@ -99,13 +104,13 @@ TRACE_EVENT(foo_bar,
99 * 104 *
100 * #define TRACE_INCLUDE_PATH ../../samples/trace_events 105 * #define TRACE_INCLUDE_PATH ../../samples/trace_events
101 * 106 *
102 * But I chose to simply make it use the current directory and then in 107 * But the safest and easiest way to simply make it use the directory
103 * the Makefile I added: 108 * that the file is in is to add in the Makefile:
104 * 109 *
105 * CFLAGS_trace-events-sample.o := -I$(PWD)/samples/trace_events/ 110 * CFLAGS_trace-events-sample.o := -I$(src)
106 * 111 *
107 * This will make sure the current path is part of the include 112 * This will make sure the current path is part of the include
108 * structure for our file so that we can find it. 113 * structure for our file so that define_trace.h can find it.
109 * 114 *
110 * I could have made only the top level directory the include: 115 * I could have made only the top level directory the include:
111 * 116 *
@@ -115,8 +120,8 @@ TRACE_EVENT(foo_bar,
115 * 120 *
116 * #define TRACE_INCLUDE_PATH samples/trace_events 121 * #define TRACE_INCLUDE_PATH samples/trace_events
117 * 122 *
118 * But then if something defines "samples" or "trace_events" then we 123 * But then if something defines "samples" or "trace_events" as a macro
119 * could risk that being converted too, and give us an unexpected 124 * then we could risk that being converted too, and give us an unexpected
120 * result. 125 * result.
121 */ 126 */
122#undef TRACE_INCLUDE_PATH 127#undef TRACE_INCLUDE_PATH