From: Thomas Gleixner <tglx@linutronix.de>
To: Jerry Snitselaar <jsnitsel@redhat.com>, linux-kernel@vger.kernel.org
Cc: linux-integrity@vger.kernel.org, intel-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org,
Jani Nikula <jani.nikula@linux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Jarkko Sakkinen <jarkko@kernel.org>,
Jason Gunthorpe <jgg@ziepe.ca>, Peter Huewe <peterhuewe@gmx.de>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
Matthew Garrett <mjg59@google.com>,
Hans de Goede <hdegoede@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 2/4] drm/i915/pmu: Use kstat_irqs to get interrupt count
Date: Sun, 06 Dec 2020 22:33:09 +0100 [thread overview]
Message-ID: <87o8j67h7u.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <875z5e99ez.fsf@nanos.tec.linutronix.de>
On Sun, Dec 06 2020 at 17:38, Thomas Gleixner wrote:
> On Fri, Dec 04 2020 at 18:43, Jerry Snitselaar wrote:
>> Now that kstat_irqs is exported, get rid of count_interrupts in
>> i915_pmu.c
>
> May I ask why this has been merged in the first place?
>
> Nothing in a driver has ever to fiddle with the internals of an irq
> descriptor. We have functions for properly accessing them. Just because
> C allows to fiddle with everything is not a justification. If the
> required function is not exported then adding the export with a proper
> explanation is not asked too much.
>
> Also this lacks protection or at least a comment why this can be called
> safely and is not subject to a concurrent removal of the irq descriptor.
> The same problem exists when calling kstat_irqs(). It's even documented
> at the top of the function.
And as pointed out vs. that TPM thing this really could have been a
trivial
i915->irqs++;
in the interrupt handler and a read of that instead of iterating over
all possible cpus and summing it up. Oh well...
Thanks,
tglx
next prev parent reply other threads:[~2020-12-06 21:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-05 1:43 [PATCH v3 0/4] tpm_tis: Detect interrupt storms Jerry Snitselaar
2020-12-05 1:43 ` [PATCH v3 1/4] irq: export kstat_irqs Jerry Snitselaar
2020-12-05 10:39 ` Jarkko Sakkinen
2020-12-06 16:40 ` Thomas Gleixner
2020-12-06 17:40 ` James Bottomley
2020-12-06 19:29 ` Thomas Gleixner
2020-12-06 17:54 ` Thomas Gleixner
2020-12-06 21:46 ` Jerry Snitselaar
2020-12-05 1:43 ` [PATCH v3 2/4] drm/i915/pmu: Use kstat_irqs to get interrupt count Jerry Snitselaar
2020-12-06 16:38 ` Thomas Gleixner
2020-12-06 21:33 ` Thomas Gleixner [this message]
2020-12-08 9:54 ` Jarkko Sakkinen
2020-12-06 21:47 ` Jerry Snitselaar
2020-12-06 23:38 ` Thomas Gleixner
2020-12-10 7:53 ` [Intel-gfx] " Joonas Lahtinen
2020-12-10 10:45 ` Tvrtko Ursulin
2020-12-10 16:35 ` Thomas Gleixner
2020-12-10 17:09 ` Tvrtko Ursulin
2020-12-10 17:44 ` Thomas Gleixner
2020-12-10 17:51 ` Tvrtko Ursulin
2020-12-05 1:43 ` [PATCH v3 3/4] tpm_tis: Disable interrupts if interrupt storm detected Jerry Snitselaar
2020-12-06 19:26 ` Thomas Gleixner
2020-12-07 19:28 ` Jason Gunthorpe
2020-12-07 19:58 ` James Bottomley
2020-12-08 17:43 ` Jarkko Sakkinen
2020-12-08 17:42 ` Jarkko Sakkinen
2020-12-05 1:43 ` [PATCH v3 4/4] tpm_tis: Disable Interrupts on the ThinkPad L490 Jerry Snitselaar
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