Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210330080615.21938-1-lecopzer.chen@mediatek.com> <20210330083218.22285-1-lecopzer.chen@mediatek.com>
In-Reply-To: <20210330083218.22285-1-lecopzer.chen@mediatek.com>
From:   Sumit Garg <sumit.garg@linaro.org>
Date:   Tue, 30 Mar 2021 18:00:39 +0530
Message-ID: <CAFA6WYMqLMEG2s7OdNweQKkP0K2LZ575B1BVw-zfsg7_KBSM5Q@mail.gmail.com>
Subject: Re: [PATCH v5] arm64: Enable perf events based hard lockup detector
To:     Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc:     Alexandru Elisei <alexandru.elisei@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Douglas Anderson <dianders@chromium.org>,
        Lecopzer Chen <lecopzer@gmail.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Stephen Boyd <swboyd@chromium.org>,
        Will Deacon <will@kernel.org>, yj.chiang@mediatek.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, 30 Mar 2021 at 14:07, Lecopzer Chen <lecopzer.chen@mediatek.com> wrote:
>
> > > Hi Will, Mark,
> > >
> > > On Fri, 15 Jan 2021 at 17:32, Sumit Garg <sumit.garg@linaro.org> wrote:
> > > >
> > > > With the recent feature added to enable perf events to use pseudo NMIs
> > > > as interrupts on platforms which support GICv3 or later, its now been
> > > > possible to enable hard lockup detector (or NMI watchdog) on arm64
> > > > platforms. So enable corresponding support.
> > > >
> > > > One thing to note here is that normally lockup detector is initialized
> > > > just after the early initcalls but PMU on arm64 comes up much later as
> > > > device_initcall(). So we need to re-initialize lockup detection once
> > > > PMU has been initialized.
> > > >
> > > > Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> > > > ---
> > > >
> > > > Changes in v5:
> > > > - Fix lockup_detector_init() invocation to be rather invoked from CPU
> > > >   binded context as it makes heavy use of per-cpu variables and shouldn't
> > > >   be invoked from preemptible context.
> > > >
> > >
> > > Do you have any further comments on this?
> > >
> > > Lecopzer,
> > >
> > > Does this feature work fine for you now?
> >
> > This really fixes the warning, I have a real hardware for testing this now.

Thanks for the testing. I assume it as an implicit Tested-by.

> > but do we need to call lockup_detector_init() for each cpu?
> >
> > In init/main.c, it's only called by cpu 0 for once.
>
> Oh sorry, I just misread the code, please ignore previous mail.
>

No worries.

-Sumit

>
> BRs,
> Lecopzer