linux-kernel - Re: [PATCH v7 1/4] x86/smp: Allow calling mwait_play

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Message-ID: <CAJZ5v0i=_wNubB8_yQtBZYLYJ+f==c9OVMpxbtYHfFCJR+nsng@mail.gmail.com>
Date: Tue, 17 Dec 2024 21:45:44 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Patryk Wlazlyn <patryk.wlazlyn@...ux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, x86@...nel.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org, rafael.j.wysocki@...el.com, peterz@...radead.org, 
	dave.hansen@...ux.intel.com, gautham.shenoy@....com, tglx@...utronix.de, 
	len.brown@...el.com, artem.bityutskiy@...ux.intel.com
Subject: Re: [PATCH v7 1/4] x86/smp: Allow calling mwait_play_dead with an
 arbitrary hint

On Tue, Dec 17, 2024 at 9:09 PM Patryk Wlazlyn
<patryk.wlazlyn@...ux.intel.com> wrote:
>
> > And honestly I'm wondering why adding a parameter to mwait_play_dead()
> > is better than introducing mwait_play_dead_with_hint(), in analogy
> > with the existing mwait_idle_with_hints()?
> >
> > The latter option would allow you to avoid introducing a function that
> > is deleted in the same patch series (in patch 4).
>
> We need to be able to call part of the old mwait_play_dead() code,
> but without the hint calculation.
>
> mwait_idle_with_hints() doesn't have the "kexec hack" logic.

Well, "in analogy" doesn't mean to use mwait_idle_with_hints() instead
of the new function.

Just the name of the new function could be similar to
mwait_idle_with_hints() (which is the name of an existing function),
that is mwait_play_dead_with_hint().

> We also need to leave the old code working and on top of that introduce
> the acpi_idle and intel_idle patches that use the new API.

Sure.  If the name of the new function is mwait_play_dead_with_hint(),
that will still work.