linux-kernel - Re: [PATCH RESEND 5/6 v10] gpio: Add device tree support to block GPIO API

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Message-ID: <20121218163502.GB32484@e106331-lin.cambridge.arm.com>
Date:	Tue, 18 Dec 2012 16:35:02 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Roland Stigge <stigge@...com.de>
Cc:	"rmallon@...il.com" <rmallon@...il.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
	"broonie@...nsource.wolfsonmicro.com" 
	<broonie@...nsource.wolfsonmicro.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"wg@...ndegger.com" <wg@...ndegger.com>,
	"w.sang@...gutronix.de" <w.sang@...gutronix.de>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"daniel-gl@....net" <daniel-gl@....net>, "sr@...x.de" <sr@...x.de>,
	"plagnioj@...osoft.com" <plagnioj@...osoft.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"highguy@...il.com" <highguy@...il.com>
Subject: Re: [PATCH RESEND 5/6 v10] gpio: Add device tree support to block
 GPIO API

On Tue, Dec 18, 2012 at 02:30:23PM +0000, Roland Stigge wrote:
> Hi Mark,
> 
> On 12/17/2012 04:51 PM, Mark Rutland wrote:
> >> +static int __devinit gpioblock_of_probe(struct platform_device *pdev)
> >> +{
> >> +	struct device_node *block;
> >> +	unsigned *gpios;
> >> +	int ngpio;
> >> +	int ret;
> >> +	struct gpio_block *gb;
> >> +
> >> +	for_each_available_child_of_node(pdev->dev.of_node, block) {
> >> +		int i;
> >> +
> >> +		ngpio = of_gpio_count(block);
> >> +		gpios = kzalloc(ngpio * sizeof(*gpios), GFP_KERNEL);
> > 
> > What if the block node is malformed? ngpio might be -ENOENT or -EINVAL.
> 
> AFAICS, of_gpio_count() always returns at least 0. Both if
> CONFIG_OF_GPIO is y, m or n. And called of_gpio_named_count() also
> currently doesn't return error values. Further, other drivers using
> of_gpio_count() don't expect or catch <0.

Whoops. I'd managed to misread the logic in of_gpio_named_count, sorry.

> However, it's reasonable to guard against of_gpio_count() < 1 since
> probing without provided blocks should be void.
> 
> Will change this for the next patch update together with your leakage
> findings.
> 
> Thanks for reporting!
> 
> Roland

Sounds good!

Thanks,
Mark.

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