Re: [PATCH 3/4] tracing: Add stack_tracer_disable/enable() functions

Steven Rostedt
2017-04-06T23:58:01Z

On Thu, 6 Apr 2017 15:08:21 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:

> On Thu, Apr 06, 2017 at 05:23:48PM -0400, Steven Rostedt wrote:
> > On Thu, 6 Apr 2017 13:21:17 -0700
> > "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> >
> > > > My worry is that we add another caller that doesn't disable interrupts
> > > > or preemption.
> > > >
> > > > I could add a __stack_trace_disable() that skips the disabling of
> > > > preemption, as the "__" usually denotes the call is "special".
> > >
> > > Given that interrupts are disabled at that point, and given also that
> > > NMI skips stack tracing if growth is required, could we just leave
> > > out the stack_tracer_disable() and stack_tracer_enable()?
> >
> > There may be other use cases. Hmm, maybe I'll just have it do a check
> > to make sure preemption is disabled. Something like:
> >
> > if (IS_ENABLED(CONFIG_DEBUG_PREEMPT))
> > WARN_ON_ONCE(!preempt_count());
>
> This in the include/linux/ftrace.h file so that it can be inlined?
> That makes sense to me.
>

Hah, I already had that part (inlining) written. It's a separate patch
though. I'll post another series tomorrow.

-- Steve