linux-kernel - Re: [PATCH v2 17/17] irq: remove handle_domain

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Message-ID: <20220511085741.GA6558@wunner.de>
Date:   Wed, 11 May 2022 10:57:41 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>, maz@...nel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        linux-gpio@...r.kernel.org,
        Octavian Purdila <octavian.purdila@....com>,
        linux-kernel@...r.kernel.org, aou@...s.berkeley.edu,
        catalin.marinas@....com, deanbo422@...il.com, green.hu@...il.com,
        guoren@...nel.org, jonas@...thpole.se, kernelfans@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux@...linux.org.uk,
        nickhu@...estech.com, palmer@...belt.com, paul.walmsley@...ive.com,
        shorne@...il.com, stefan.kristiansson@...nalahti.fi,
        tsbogend@...ha.franken.de, vgupta@...nel.org,
        vladimir.murzin@....com, will@...nel.org,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v2 17/17] irq: remove handle_domain_{irq,nmi}()

On Wed, May 11, 2022 at 09:23:56AM +0100, Mark Rutland wrote:
> On Wed, May 11, 2022 at 12:52:29AM +0200, Thomas Gleixner wrote:
> > +	/* USB interrupts are received in softirq (tasklet) context.
> > +	 * Switch to hardirq context to make genirq code happy.
> > +	 */
> > +	local_irq_save(flags);
> > +	__irq_enter_raw();
> > +
> >  	if (intdata & INT_ENP_PHY_INT_)
> > -		;
> > +		generic_handle_domain_irq(pdata->irqdomain, PHY_HWIRQ);
> 
> Agreed. IIUC everyone agrees the __irq_enter_raw() usage is a hack,
> but what's not clear is what we *should* do
> 
> I suspect that given we have generic_handle_irq_safe() for situations
> like this we should add a generic_handle_domain_irq_safe(), and use
> that in this driver?
> That way we can keep the `WARN_ON_ONCE(!in_hardirq())` in
> generic_handle_domain_irq().

Thomas applied 792ea6a074ae ("genirq: Remove WARN_ON_ONCE() in
generic_handle_domain_irq()") tonight:

http://git.kernel.org/tip/tip/c/792ea6a074ae

That allows me to drop the controversial __irq_enter_raw()
and thus unblock my smsc95xx series.

generic_handle_domain_irq_safe() would merely be a wrapper for
generic_handle_domain_irq() which disables local interrupts.
Then I wouldn't have to do that in smsc95xx.c.  IMHO that's a
cosmetic improvement, though I'll be happy to provide a patch
if desired?

Thanks,

Lukas