linux-kernel - Re: [PATCH v4 6/6] arm64: Enable perf events based hard lockup detector

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Date:   Thu, 26 May 2022 17:35:40 +0800
From:   Lecopzer Chen <lecopzer.chen@...iatek.com>
To:     <pmladek@...e.com>
CC:     <acme@...nel.org>, <akpm@...ux-foundation.org>,
        <alexander.shishkin@...ux.intel.com>, <catalin.marinas@....com>,
        <davem@...emloft.net>, <jolsa@...hat.com>, <jthierry@...hat.com>,
        <keescook@...omium.org>, <kernelfans@...il.com>,
        <lecopzer.chen@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-perf-users@...r.kernel.org>, <mark.rutland@....com>,
        <masahiroy@...nel.org>, <matthias.bgg@...il.com>, <maz@...nel.org>,
        <mcgrof@...nel.org>, <mingo@...hat.com>, <namhyung@...nel.org>,
        <nixiaoming@...wei.com>, <peterz@...radead.org>,
        <sparclinux@...r.kernel.org>, <sumit.garg@...aro.org>,
        <wangqing@...o.com>, <will@...nel.org>, <yj.chiang@...iatek.com>
Subject: Re: [PATCH v4 6/6] arm64: Enable perf events based hard lockup detector

> > to re-initialize lockup detection once PMU has been initialized.
> > 
> > [1]: http://lore.kernel.org/linux-arm-kernel/1610712101-14929-1-git-send-email-sumit.garg@linaro.org
> > 
> > --- a/arch/arm64/kernel/perf_event.c
> > +++ b/arch/arm64/kernel/perf_event.c
> > @@ -1390,10 +1391,15 @@ static struct platform_driver armv8_pmu_driver = {
> >  
> >  static int __init armv8_pmu_driver_init(void)
> >  {
> > +	int ret;
> > +
> >  	if (acpi_disabled)
> > -		return platform_driver_register(&armv8_pmu_driver);
> > +		ret = platform_driver_register(&armv8_pmu_driver);
> >  	else
> > -		return arm_pmu_acpi_probe(armv8_pmuv3_pmu_init);
> > +		ret = arm_pmu_acpi_probe(armv8_pmuv3_pmu_init);
> > +
> > +	retry_lockup_detector_init();
> 
> Does it makes sense to call retry_lockup_detector_init() when
> the above returned an error? Should it be?
> 
> 	if (!ret)
> 		retry_lockup_detector_init();

Oh I think you're right, I'll add a checking here.
> 
> > +	return ret;
> >  }
> >  device_initcall(armv8_pmu_driver_init)
> 
> 
> I am not qualified to ack the arm-specific code. But otherwise
> the change looks reasonable.

Thanks for your help, I'l rebase on 5.19 -rc1 and seek reviewing for
ARM relative part.


thanks
BRs,
Lecopzer