linux-kernel - Re: [PATCH v3 1/4] irq: export kstat

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Message-ID: <87lfeahakt.fsf@redhat.com>
Date:   Sun, 06 Dec 2020 14:46:26 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        kernel test robot <lkp@...el.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Peter Huewe <peterhuewe@....de>,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        Matthew Garrett <mjg59@...gle.com>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v3 1/4] irq: export kstat_irqs


Thomas Gleixner @ 2020-12-06 10:54 MST:

> Jerry,
>
> On Fri, Dec 04 2020 at 18:43, Jerry Snitselaar wrote:
>
> The proper prefix is 'genirq:' git log kernel/irq/irqdesc.c would have
> told you. 
>
>> To try and detect potential interrupt storms that
>> have been occurring with tpm_tis devices it was suggested
>> to use kstat_irqs() to get the number of interrupts.
>> Since tpm_tis can be built as a module it needs kstat_irqs
>> exported.
>
> I'm not really enthused about exporting this without making it at least
> safe. Using it from an interrupt handler is obviously safe vs. concurrent
> removal, but the next driver writer who thinks this is cool is going to
> get it wrong for sure.
>
> Though I still have to figure out what the advantage of invoking a
> function which needs to do a radix tree lookup over a device local
> counter is just to keep track of this.
>
> I'll reply on the TPM part of this as well.
>
> Thanks,
>
>         tglx

I can rework it to use a device local counter.