linux-kernel - Re: [PATCH v2 1/4] genirq: Walk the irq_data hierarchy when resending an interrupt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <878sdomv5i.wl-maz@kernel.org>
Date:   Sat, 05 Sep 2020 10:26:33 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Valentin Schneider <valentin.schneider@....com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Jason Cooper <jason@...edaemon.net>,
        Thomas Gleixner <tglx@...utronix.de>, kernel-team@...roid.com
Subject: Re: [PATCH v2 1/4] genirq: Walk the irq_data hierarchy when resending an interrupt

Hi Valentin,

On Fri, 04 Sep 2020 20:28:38 +0100,
Valentin Schneider <valentin.schneider@....com> wrote:
> 
> 
> Hi Marc,
> 
> On 03/09/20 19:32, Marc Zyngier wrote:
> > On resending an interrupt, we only check the topmost irqchip for
> > a irq_retrigger callback. However, this callback could be implemented
> > at a lower level. Use irq_chip_retrigger_hierarchy() in this case.
> >
> 
> Rookie wording question here; re-reading this I'm questioning which way is
> up.
> 
> From an irq_data hierarchy PoV, the topmost chip (i.e. last ->parent)
> should be the root irqchip. However, the irq_desc we get from irq_to_desc()
> ought to hold the irq_data for the lowermost irqchip in that irq_data
> hierarchy.
> 
> Is it that here by "topmost" you instead mean topmost of the irqchip stack
> on top of the root (IOW furthest away from the root)?

That's indeed what I mean, but I agree that the terminology is
confusing, and often used inconsistently (by me included).

<random>
Maybe considering the irqchip stack along a vertical axis is the wrong
thing to do, and that looking at it as a volume would be marginally
better?

How about innermost (close to the CPU) vs outermost (close to the
device)?
</random>

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.