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-rw-r--r--Documentation/trace/tracepoints.txt19
1 files changed, 17 insertions, 2 deletions
diff --git a/Documentation/trace/tracepoints.txt b/Documentation/trace/tracepoints.txt
index da49437..ac4170d 100644
--- a/Documentation/trace/tracepoints.txt
+++ b/Documentation/trace/tracepoints.txt
@@ -40,7 +40,13 @@ Two elements are required for tracepoints :
In order to use tracepoints, you should include linux/tracepoint.h.
-In include/trace/subsys.h :
+In include/trace/events/subsys.h :
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM subsys
+
+#if !defined(_TRACE_SUBSYS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SUBSYS_H
#include <linux/tracepoint.h>
@@ -48,10 +54,16 @@ DECLARE_TRACE(subsys_eventname,
TP_PROTO(int firstarg, struct task_struct *p),
TP_ARGS(firstarg, p));
+#endif /* _TRACE_SUBSYS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
+
In subsys/file.c (where the tracing statement must be added) :
-#include <trace/subsys.h>
+#include <trace/events/subsys.h>
+#define CREATE_TRACE_POINTS
DEFINE_TRACE(subsys_eventname);
void somefct(void)
@@ -72,6 +84,9 @@ Where :
- TP_ARGS(firstarg, p) are the parameters names, same as found in the
prototype.
+- if you use the header in multiple source files, #define CREATE_TRACE_POINTS
+ should appear only in one source file.
+
Connecting a function (probe) to a tracepoint is done by providing a
probe (function to call) for the specific tracepoint through
register_trace_subsys_eventname(). Removing a probe is done through
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