Re: [PATCH] ftrace: trigger: Call traceoff trigger after event recorded

[Steven Rostedt]

On Fri, 23 Sep 2016 22:11:33 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> Ping?

Thanks for the ping. I've been hacking on other things lately that,
even though I marked this as "todo", it has falling in my INBOX abyss.

I'll take a look at this today.

-- Steve

> 
> On Fri,  9 Sep 2016 01:05:45 +0900
> Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> 
> > Call traceoff trigger after the event is recorded.
> > Since current traceoff trigger is called before recording
> > the event, we can not know when the trace is off by what event.
> > 
> > Typical usecase of traceoff/traceon trigger is tracing
> > function calls and trace events between a pair of events.
> > For example, trace function calls between syscall entry/exit.
> > In that case, it is useful if we can see the return code
> > of the target syscall.
> > 
> > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > ---
> >  kernel/trace/trace_events_trigger.c |    1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
> > index a975571..6721a1e8 100644
> > --- a/kernel/trace/trace_events_trigger.c
> > +++ b/kernel/trace/trace_events_trigger.c
> > @@ -1028,6 +1028,7 @@ static struct event_command trigger_traceon_cmd = {
> >  static struct event_command trigger_traceoff_cmd = {
> >  	.name			= "traceoff",
> >  	.trigger_type		= ETT_TRACE_ONOFF,
> > +	.flags			= EVENT_CMD_FL_POST_TRIGGER,
> >  	.func			= event_trigger_callback,
> >  	.reg			= register_trigger,
> >  	.unreg			= unregister_trigger,
> >   
> 
>