From: Thomas Gleixner <tglx@linutronix.de>
To: "Herrenschmidt\, Benjamin" <benh@amazon.com>,
"maz\@kernel.org" <maz@kernel.org>, "Saidi\,
Ali" <alisaidi@amazon.com>
Cc: "jason\@lakedaemon.net" <jason@lakedaemon.net>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel\@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>, "Woodhouse\,
David" <dwmw@amazon.co.uk>, "Zilberman\, Zeev" <zeev@amazon.com>,
"Machulsky\, Zorik" <zorik@amazon.com>
Subject: Re: [PATCH] irqchip/gic-v3-its: Don't try to move a disabled irq
Date: Tue, 02 Jun 2020 22:54:14 +0200 [thread overview]
Message-ID: <87y2p5fatl.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <37e55e71faf76dc3db76d89c20c1bdfff942e380.camel@amazon.com>
"Herrenschmidt, Benjamin" <benh@amazon.com> writes:
> On Sun, 2020-05-31 at 12:09 +0100, Marc Zyngier wrote:
>> > The semantic of activate/deactivate (which maps to started/shutdown
>> > in the IRQ code) is that the HW resources for a given interrupt are
>> > only committed when the interrupt is activated. Trying to perform
>> > actions involving the HW on an interrupt that isn't active cannot be
>> > guaranteed to take effect.
>> >
>> > I'd rather address it in the core code, by preventing set_affinity (and
>> > potentially others) to take place when the interrupt is not in the
>> > STARTED state. Userspace would get an error, which is perfectly
>> > legitimate, and which it already has to deal with it for plenty of
>> > other
>> > reasons.
>
> So I finally found time to dig a bit in there :) Code has changed a bit
> since last I looked. But I have memories of the startup code messing
> around with the affinity, and here it is. In irq_startup() :
>
>
> switch (__irq_startup_managed(desc, aff, force)) {
> case IRQ_STARTUP_NORMAL:
> ret = __irq_startup(desc);
> irq_setup_affinity(desc);
> break;
> case IRQ_STARTUP_MANAGED:
> irq_do_set_affinity(d, aff, false);
> ret = __irq_startup(desc);
> break;
> case IRQ_STARTUP_ABORT:
> irqd_set_managed_shutdown(d);
> return 0;
>
> So we have two cases here. Normal and managed.
>
> In the managed case, we set the affinity before startup. I feel like your
> patch might break that or am I missing something ?
It will break stuff because the affinity is not stored in case that the
interrupt is not started.
I think we can fix this in the core code but that needs more thought.
__irq_can_set_affinity() is definitely the wrong place.
Thanks,
tglx
next prev parent reply other threads:[~2020-06-02 20:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-29 1:55 [PATCH] irqchip/gic-v3-its: Don't try to move a disabled irq Ali Saidi
2020-05-29 4:07 ` Zenghui Yu
2020-05-29 8:32 ` Marc Zyngier
2020-05-29 12:36 ` Saidi, Ali
2020-05-30 16:49 ` Marc Zyngier
2020-05-31 11:09 ` Marc Zyngier
2020-06-01 0:10 ` Saidi, Ali
2020-06-01 2:40 ` Herrenschmidt, Benjamin
2020-06-02 20:54 ` Thomas Gleixner [this message]
2020-06-03 12:44 ` Marc Zyngier
2020-05-31 2:53 ` kbuild test robot
2020-07-17 21:34 ` [tip: irq/urgent] genirq/affinity: Handle affinity setting on inactive interrupts correctly tip-bot2 for Thomas Gleixner
2020-06-02 18:47 [PATCH] irqchip/gic-v3-its: Don't try to move a disabled irq Saidi, Ali
2020-06-03 15:16 ` Marc Zyngier
2020-06-03 22:14 ` Herrenschmidt, Benjamin
2020-06-08 13:48 ` Thomas Gleixner
2020-06-08 21:59 ` Benjamin Herrenschmidt
2020-06-08 23:36 ` Thomas Gleixner
2020-06-11 17:44 Saidi, Ali
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87y2p5fatl.fsf@nanos.tec.linutronix.de \
--to=tglx@linutronix.de \
--cc=alisaidi@amazon.com \
--cc=benh@amazon.com \
--cc=dwmw@amazon.co.uk \
--cc=jason@lakedaemon.net \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=zeev@amazon.com \
--cc=zorik@amazon.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).