Re: [PATCH v12 3/3] tracing: Centralize preemptirq tracepoints and unify their usage

From: Paul E. McKenney
Date: Wed Aug 08 2018 - 13:21:11 EST

On Wed, Aug 08, 2018 at 12:24:04PM -0400, Steven Rostedt wrote:
> On Wed, 8 Aug 2018 09:02:43 -0700
> "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> > > Which leaves us with sparc, arm, mips, sh and powerpc.
> > >
> > > sh is almost dead, and powerpc can be fixed, which I guess leaves us
> > > with sparc, arm and mips.
> >
> > If we want to stick with the current srcu_read_lock() and srcu_read_unlock(),
> > you mean? I would like that sort of outcome, at least assuming we are not
> > hammering any of the architectures.
> I would go with the local_inc approach, and even add a
> srcu_read_un/lock_nmi() that does that if you want. Probably should add
> lockdep to detect if the _nmi calls is ever used along with non _nmi
> calls and complain about that.

Would it be reasonable to also add a check for non-_nmi calls being
used in both NMI and non-NMI contexts?

> But this will be something for the next merge window, not the one
> coming up.

Completely agreed!

Thanx, Paul