linux-kernel - Re: [PATCH 03/23] gpio: sysfs: drop redundant lock-as-irq

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Date:	Thu, 30 Apr 2015 11:07:58 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Johan Hovold <johan@...nel.org>,
	Alexandre Courbot <gnurou@...il.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/23] gpio: sysfs: drop redundant lock-as-irq

On Wed, Apr 29, 2015 at 11:48:57PM +0200, Linus Walleij wrote:
> On Tue, Apr 21, 2015 at 5:42 PM, Johan Hovold <johan@...nel.org> wrote:
> 
> > Drop redundant lock-as-irq in gpio_setup_irq, which has already been
> > handled when requesting and releasing the irq (i.e. in the irq chip
> > irq_request_resources and irq_release_resources callbacks).
> 
> Well we would hope they all do that. And I hope for the vast majority
> that is true, but there is a TODO to go over all gpiochip drivers
> (some which are elsewhere in the kernel than drivers/gpio) and
> make sure they actually do so.
> 
> Right now it's a bit arbitrary if so happens, and in not marked by
> the driver as IRQ then this kicks in and provides an additional
> protection.
> 
> But maybe that's overzealous, what do people say?

No, you're right. The drivers that fail to do this needs to be fixed,
but the "redundant" lock-as-irq in the sysfs interface should not be
removed before that.

I'll respin the series and add it back with a comment explaining why
gpiochip_lock_as_irq is currently called twice.

Thanks,
Johan
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