Re: [PATCH v4 4/4] platform/x86: ideapad-laptop: add a mutex to synchronize VPC commands

[Ilpo Järvinen]

On Tue, 30 Jul 2024, Gergo Koteles wrote:
> On Tue, 2024-07-30 at 16:37 +0300, Ilpo Järvinen wrote:
> > On Thu, 25 Jul 2024, Gergo Koteles wrote:
> > 
> > > Calling VPC commands consists of several VPCW and VPCR ACPI calls.
> > > These calls and their results can get mixed up if they are called
> > > simultaneously from different threads, like acpi notify handler,
> > > sysfs, debugfs, notification chain.
> > > 
> > > Add a mutex to synchronize VPC commands.
> > > 
> > > Signed-off-by: Gergo Koteles <soyer@xxxxxx>
> > 
> > What commit does this fix? I was going to add a Fixes tag myself while 
> > applying this but wasn't sure if it should be the ACPI concurrency commit 
> > e2ffcda16290 or the change introducing lenovo-ymc driver?
> > 
> 
> YMC triggering works in 6.7, but not reliably in 6.8. So I assume the
> culprit is e2ffcda16290.
>
> But in theory debugfs, sysfs, acpi notify handler can race with each
> other in the same way for 10+ years. Technically, probably not.

Okay, I decided to put both commits then as the ACPI thing made it much 
worse so it's proper to assign some "blame" to it for the additional 
problems it caused ;-). I also wrote an additional paragraph about it
into the commit message.

> > Also, I'd prefer to not take the move patch (PATCH 3/4) now so I could 
> > take this through fixes branch since it causes a real issue if I remember 
> > the earlier discussions right? Do you think there's any issue if I take 
> > only patches 1, 2, and 4? They seemed to apply without conflicts when I 
> > tried to apply the entire series and then cherrypicked the last patch 
> > dropping the third patch.
> > 
> 
> Yes, this is a real issue.
> 
> You can skip the third patch. The series compiles and works fine
> without it.
> 
> > The code movement patch could go through for-next fixes branch is then 
> > merged into it (or after one kernel cycle).
> > 
> > 
> 
> Fine.

I've taken patches 1, 2, and 4 into review-ilpo and will propagate them 
into fixes branch once LKP has build tested the branch.

Thanks for the patches!


As mentioned patch 3 should go to for-next which is handled by Hans in 
this cycle. It requires merging the fixes branch (or the fixes PR tag) 
into for-next once the other commits have migrated into fixes. I'll 
reassign patch 3 to Hans in patchwork once I've tagged the PR to Linus.

-- 
 i.