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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2015-02-09 16:32:19 -0500
committerSteven Rostedt <rostedt@goodmis.org>2015-02-09 18:05:39 -0500
commit6adc13f8c096736957444ffa2aa11421b5671aef (patch)
tree705f6ba74c25d29405f80e339a6562c81d145018 /samples/trace_events/trace-events-sample.h
parentc4c7eb29382c456b9be9858c357a490ae0ccd0f6 (diff)
downloadlinux-6adc13f8c096736957444ffa2aa11421b5671aef.tar.gz
tracing: Add TRACE_EVENT_FN example
If a function should be called before a tracepoint is enabled and/or after it is disabled, the TRACE_EVENT_FN() serves this purpose. But it is not well documented. Having it as a sample would help developers to know how to use it. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'samples/trace_events/trace-events-sample.h')
-rw-r--r--samples/trace_events/trace-events-sample.h44
1 files changed, 44 insertions, 0 deletions
diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h
index c3232340914d..d0be8411b527 100644
--- a/samples/trace_events/trace-events-sample.h
+++ b/samples/trace_events/trace-events-sample.h
@@ -270,6 +270,50 @@ TRACE_EVENT_CONDITION(foo_bar_with_cond,
TP_printk("foo %s %d", __get_str(foo), __entry->bar)
);
+
+void foo_bar_reg(void);
+void foo_bar_unreg(void);
+
+/*
+ * Now in the case that some function needs to be called when the
+ * tracepoint is enabled and/or when it is disabled, the
+ * TRACE_EVENT_FN() serves this purpose. This is just like TRACE_EVENT()
+ * but adds two more parameters at the end:
+ *
+ * TRACE_EVENT_FN( name, proto, args, struct, assign, printk, reg, unreg)
+ *
+ * reg and unreg are functions with the prototype of:
+ *
+ * void reg(void)
+ *
+ * The reg function gets called before the tracepoint is enabled, and
+ * the unreg function gets called after the tracepoint is disabled.
+ *
+ * Note, reg and unreg are allowed to be NULL. If you only need to
+ * call a function before enabling, or after disabling, just set one
+ * function and pass in NULL for the other parameter.
+ */
+TRACE_EVENT_FN(foo_bar_with_fn,
+
+ TP_PROTO(const char *foo, int bar),
+
+ TP_ARGS(foo, bar),
+
+ TP_STRUCT__entry(
+ __string( foo, foo )
+ __field( int, bar )
+ ),
+
+ TP_fast_assign(
+ __assign_str(foo, foo);
+ __entry->bar = bar;
+ ),
+
+ TP_printk("foo %s %d", __get_str(foo), __entry->bar),
+
+ foo_bar_reg, foo_bar_unreg
+);
+
#endif
/***** NOTICE! The #if protection ends here. *****/