Re: [PATCH v7 00/16] tracing: probeevent: Improve fetcharg features

[Steven Rostedt]

On Sat, 5 May 2018 11:38:03 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> On Fri, 4 May 2018 12:06:42 -0400
> Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> 
> > On Sat, 5 May 2018 00:48:28 +0900
> > Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> >   
> > > So the syntax will be
> > > 
> > > p[:EVENT] SYM[(CAST)|+OFFS] [FETCHARG]
> > > 
> > > And here is an example;
> > > 
> > > p:myevent vfs_read(void *file, char *buf, size_t count, void *pos) $arg1 $arg2  
> > 
> > If we do this, why bother with $arg1 $arg2?  
> 
> User may want to trace only some of them. :)

Yes, and this is why I like my solution of the NULL parameter, and you
don't need to show anything after what you want.

 p:myevent vfs_read(void *file, NULL, size_t count)

would only trace file and count, and ignore buf and pos.

-- Steve