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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 20 Nov 2019 10:08:50 +0100
Message-ID: <CAJZ5v0i1UqdQBvXm1cozOQeQ8YRdTxOAQPP9=RyZHHnsmuGHTw@mail.gmail.com>
Subject: Re: [RFT][PATCH 1/3] PM: QoS: Introduce frequency QoS
To:     Doug Smythies <dsmythies@telus.net>
Cc:     "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Linux ACPI <linux-acpi@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Dmitry Osipenko <digetx@gmail.com>
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On Wed, Nov 20, 2019 at 7:55 AM Doug Smythies <dsmythies@telus.net> wrote:
>
> On 2019.11.19 14:14 Rafael J. Wysocki wrote:
> > On Tuesday, November 19, 2019 8:17:05 PM CET Rafael J. Wysocki wrote:
>
> ...
>
> >> However, I now also see that freq_qos_remove_request() doesn't clear
> >> the qos field in req which is should do, so freq_qos_add_request()
> >> will complain and fail if the object pointed to by req is passed to it
> >> again.
> >>
> >> I'll send a patch to test for this later today.
> >>
> >
> > The patch is appended.  Please test it (on top of 5.4-rc8) and report back.
> >
> > ---
> > kernel/power/qos.c |    8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > Index: linux-pm/kernel/power/qos.c
> > ===================================================================
> > --- linux-pm.orig/kernel/power/qos.c
> > +++ linux-pm/kernel/power/qos.c
> > @@ -814,6 +814,8 @@ EXPORT_SYMBOL_GPL(freq_qos_update_reques
> >  */
> > int freq_qos_remove_request(struct freq_qos_request *req)
> > {
> > +     int ret;
> > +
> >       if (!req)
> >               return -EINVAL;
> >
> > @@ -821,7 +823,11 @@ int freq_qos_remove_request(struct freq_
> >                "%s() called for unknown object\n", __func__))
> >               return -EINVAL;
> >
> > -     return freq_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
> > +     ret = freq_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
> > +     req->qos = NULL;
> > +     req->type = 0;
> > +
> > +     return ret;
> >  }
> >  EXPORT_SYMBOL_GPL(freq_qos_remove_request);
>
> Yes the patch fixes the problem. Thanks.
>
> I tested several hundred times switching between
> passive and active modes with the intel_pstate driver,
> including with various CPUs disabled and re-enabled.

Thanks a lot!

Let me resend the patch with a changelog and tags.