Re: [PATCH] cpufreq, store_scaling_governor requires policy->rwsem to be held for duration of changing governors [v2]

From: Rafael J. Wysocki
Date: Thu Jul 31 2014 - 12:18:18 EST


On Thursday, July 31, 2014 06:23:18 AM Prarit Bhargava wrote:
>
> On 07/30/2014 10:16 PM, Rafael J. Wysocki wrote:
> > On Wednesday, July 30, 2014 06:36:00 PM Saravana Kannan wrote:
> >> On 07/30/2014 02:40 PM, Rafael J. Wysocki wrote:
> >>> On Wednesday, July 30, 2014 10:18:25 AM Prarit Bhargava wrote:
> >>>>
> >>>> On 07/29/2014 08:03 PM, Rafael J. Wysocki wrote:
> >>>>> On Tuesday, July 29, 2014 07:46:02 AM Prarit Bhargava wrote:
> >>>
> >>> [cut]
> >>>
> >>>>>> This patch effectively reverts commit 955ef483.
> >>
> >> The issue reported in this patch is valid. We are seeing that internally
> >> too. I believe I reported it in another thread (within the past month).
> >>
> >> However, the original patch fixes a real deadlock issue (I'm too tired
> >> to look it up now). We can revet the original, but it's going to bring
> >> back the original issue. I just want to make sure Prarit and Raphael
> >> realize this before proceeding.
> >>
> >> I do have plans for a proper fix for the mainline (not stable branches),
> >> but plan to do that after the current set of suspend/hotplug patches go
> >> through. The fix would be easier to make after that.
> >>
> >>>>>
> >>>>> OK, I'm convinced by this.
> >>>>>
> >>>>> I suppose we should push it for -stable from 3.10 through 3.15.x, right?
> >>>>
> >>>> Rafael, I think that is a good idea. I'm not sure what the protocol is for
> >>>> adding stable@xxxxxxxxxx though ...
>
> Rafael, let me (again) re-write the patch description. I think Saravana has
> raised an important issue that I have not clearly identified why it is safe to
> remove this code in my patch description. Also, I want to clearly identify the
> appropriate -stable releases to push this out to.
>
> I'll submit a [v3] later today or tomorrow.

In any case that's too late for 3.16 final, unless there's an -rc8.

Thanks for doing that work!

Rafael

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