Linux GPIO subsystem development
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From: Kent Gibson <warthog618@gmail.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Adrian Ambrozewicz <aambrozewicz@nvidia.com>,
	Bartosz Golaszewski <brgl@kernel.org>,
	Linus Walleij <linusw@kernel.org>,
	Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Herve Codina <herve.codina@bootlin.com>,
	Jia Jia <physicalmtea@gmail.com>,
	linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2 6/6] gpiolib: let the character device free its IRQs first on chip removal
Date: Mon, 19 Oct 2026 17:00:13 +0800	[thread overview]
Message-ID: <20261019090013.GA29798@rigel> (raw)
In-Reply-To: <atXXi_EA6iROhK0C@ashevche-desk.local>

On Mon, Oct 19, 2026 at 11:40:43AM +0300, Andy Shevchenko wrote:
> On Fri, Oct 16, 2026 at 09:40:03PM +0800, Kent Gibson wrote:
> > On Fri, Oct 16, 2026 at 12:23:38PM +0300, Adrian Ambrozewicz wrote:
> 
> ...
> 
> > > +	/* Called with gdev->chip already NULL, so gpiod_to_irq() can't be used. */
> > > +	if (gc->to_irq)
> > > +		irq = gc->to_irq(gc, gpiod_hwgpio(desc));
> > > +	else
> > > +		irq = 0;
> > > +	if (irq <= 0)
> > > +		return;
> > 
> > Perhaps I'm channelling Andy here, but how about:
> 
> It was in the previous version and I suggested to move it to the above. Seems
> like we have an opposite comments. Can you provide a rationale behind your choice?
> 

Ha, so it was, though your suggestion was not quite the above - it
didn't allow for gc->to_irq() returning 0 and it set the irq to a
negative error code.

> > 	if (!gc->to_irq)
> >         return;
> > 	irq = gc->to_irq(gc, gpiod_hwgpio(desc));
> > 	if (irq <= 0)
> > 		return;
> 

This way is clearer given gc->to_irq() can return 0 - the <= condition
there is purely because of its possible return values.
Setting irq to either 0 or an negative error code, rather than just returning
on the spot, are both more confusing and pointless.

This is my preferred form, and I obviously expected that you would prefer the
shorter form as well, but apparently not.

Cheers,
Kent.


  reply	other threads:[~2026-10-19  9:01 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-16  9:23 [PATCH v2 0/6] gpiolib: fix chip removal with lines still requested from user space Adrian Ambrozewicz
2026-10-16  9:23 ` [PATCH v2 1/6] gpiolib: wait for pending label frees before cleaning up desc_srcu Adrian Ambrozewicz
2026-10-16  9:23 ` [PATCH v2 2/6] gpiolib: free the label of lines released after their chip was removed Adrian Ambrozewicz
2026-10-16 13:38   ` Andy Shevchenko
2026-10-20 12:59     ` Adrian Ambrozewicz
2026-10-16  9:23 ` [PATCH v2 3/6] gpiolib: cdev: do not free line IRQs again after the chip is removed Adrian Ambrozewicz
2026-10-16  9:23 ` [PATCH v2 4/6] gpiolib: cdev: don't sleep in the SRCU read section in read() Adrian Ambrozewicz
2026-10-16  9:23 ` [PATCH v2 5/6] gpiolib: cdev: don't leak the IRQ name when the chip is removed Adrian Ambrozewicz
2026-10-16 13:41   ` Andy Shevchenko
2026-10-20 12:59     ` Adrian Ambrozewicz
2026-10-16  9:23 ` [PATCH v2 6/6] gpiolib: let the character device free its IRQs first on chip removal Adrian Ambrozewicz
2026-10-16  9:45   ` sashiko-bot
2026-10-16 10:01     ` Adrian Ambrozewicz
2026-10-16 13:40   ` Kent Gibson
2026-10-19  8:40     ` Andy Shevchenko
2026-10-19  9:00       ` Kent Gibson [this message]
2026-10-20 12:59         ` Adrian Ambrozewicz

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