From 6adc13f8c096736957444ffa2aa11421b5671aef Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Mon, 9 Feb 2015 16:32:19 -0500 Subject: 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 --- samples/trace_events/trace-events-sample.h | 44 ++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'samples/trace_events/trace-events-sample.h') 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. *****/ -- cgit v1.2.3-59-g8ed1b