Re: [PATCH v2 0/9] Remove spin_unlock_wait()

From: Paul E. McKenney
Date: Sat Jul 08 2017 - 07:41:38 EST


On Sat, Jul 08, 2017 at 10:43:24AM +0200, Ingo Molnar wrote:
>
> * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
>
> > On Fri, Jul 07, 2017 at 10:31:28AM +0200, Ingo Molnar wrote:
> >
> > [ . . . ]
> >
> > > In fact I'd argue that any future high performance spin_unlock_wait() user is
> > > probably better off open coding the unlock-wait poll loop (and possibly thinking
> > > hard about eliminating it altogether). If such patterns pop up in the kernel we
> > > can think about consolidating them into a single read-only primitive again.
> >
> > I would like any reintroduction to include a header comment saying exactly
> > what the consolidated primitive actually does and does not do. ;-)
> >
> > > I.e. I think the proposed changes are doing no harm, and the unavailability of a
> > > generic primitive does not hinder future optimizations either in any significant
> > > fashion.
> >
> > I will have a v3 with updated comments from Manfred. Thoughts on when/where
> > to push this?
>
> Once everyone agrees I can apply it to the locking tree. I think PeterZ's was the
> only objection?

Oleg wasn't all that happy, either, but he did supply the relevant patch.

> > The reason I ask is if this does not go in during this merge window, I need
> > to fix the header comment on spin_unlock_wait().
>
> Can try it next week after some testing - let's see how busy things get for Linus
> in the merge window?

Sounds good! Either way is fine with me.

Thanx, Paul