linux-kernel - RE: [PATCH 1/1] arm64: kexec: no need to do irq_chip->irq

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Date:   Thu, 6 Aug 2020 10:09:36 +0000
From:   Jason Liu <jason.hui.liu@....com>
To:     Sudeep Holla <sudeep.holla@....com>
CC:     Marc Zyngier <maz@...nel.org>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "sashal@...nel.org" <sashal@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH 1/1] arm64: kexec: no need to do irq_chip->irq_mask if it
 already masked



> -----Original Message-----
> From: Sudeep Holla <sudeep.holla@....com>
> Sent: Wednesday, August 5, 2020 4:48 PM
> To: Jason Liu <jason.hui.liu@....com>
> Cc: Marc Zyngier <maz@...nel.org>; catalin.marinas@....com;
> will@...nel.org; sashal@...nel.org; linux-kernel@...r.kernel.org; Sudeep
> Holla <sudeep.holla@....com>; linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH 1/1] arm64: kexec: no need to do irq_chip->irq_mask if it
> already masked
> 
> On Wed, Aug 05, 2020 at 06:31:20AM +0000, Jason Liu wrote:
> > >
> > > Indeed, the runtime PM ops in that driver looks dodgy. Any calls to
> > > mask_irq from drivers or anywhere with irqchip suspended with just
> > > blows up the system.
> >
> > If you look at the chip->irq_mask implementation on different
> > platforms, almost all with directly access the register of the irqchip including
> irqsteer.
> > There are fine due to driver will use the common mask_irq API.
> >
> 
> That still doesn't explain how you can prevent system from blowing up if
> chip->irq_mask gets called with irqchip suspended ?

Do you mean driver, the driver will not call chip->irq_mask when irqchip was in suspend.
if it does, it will be big BUG. I believe we don't do that in the driver.

> 
> --
> Regards,
> Sudeep