Re: [PATCH][RFC] tracing: Enable tracepoints via module parameters

[Williams, Dan J]

[ drop Rusty, add Jessica and Emmanuel ]

On Wed, 2013-08-14 at 23:32 -0400, Steven Rostedt wrote:
> On Thu, 15 Aug 2013 11:32:10 +0930
> Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote:
> 
> > Steven Rostedt <rostedt@xxxxxxxxxxx> writes:
> > > But the thing about this that bothers me is that there's no way
> > > to say,
> > > "Enable all tracepoints in this module on load". I would like a
> > > way to
> > > do that, but I don't know of a way to do that without modifying
> > > the
> > > module code. Have any ideas? Basically, I would love to have:
> > > 
> > > insmod foo tracepoints=all
> > > 
> > > or something and have all tracepoints enabled.
> > 
> > "without modifying the module code"?  Why?  The code isn't that
> > scary,
> > and this seems useful.
> 
> I'm not afraid of the code, I'm afraid of you ;-) I hear you have
> killer puppies.
> 
> 
> OK, then when I get some time, I may cook something up.
> 
> Thanks,
> 
> -- Steve

Revive an old thread...

Steven, did you ever end up with a solution to the "enable tracing at
module load" problem?

I see some people getting admonished to use ftrace over dev_dbg() [1],
but one of the features that keeps dev_dbg() proliferating is its
generic "$mod_name.dyndbg=" module parameter support for selective
debug enabling at boot / module-load.

It would be useful to be able to do
/sys/kernel/debug/dynamic_debug/control enabling for tracepoints, but
also module::function_name patterns for "got here" style debugging. I'd
be happy to help with this, but wanted to understand where you left
things.

[1]: https://lore.kernel.org/linux-wireless/YHRFy3aq%2FgB7Vde6@xxxxxxxxx/