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

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Date:	Tue, 18 Dec 2012 15:30:23 +0100
From:	Roland Stigge <stigge@...com.de>
To:	Mark Rutland <mark.rutland@....com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"linus.walleij@...aro.org" <linus.walleij@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"w.sang@...gutronix.de" <w.sang@...gutronix.de>,
	"jbe@...gutronix.de" <jbe@...gutronix.de>,
	"plagnioj@...osoft.com" <plagnioj@...osoft.com>,
	"highguy@...il.com" <highguy@...il.com>,
	"broonie@...nsource.wolfsonmicro.com" 
	<broonie@...nsource.wolfsonmicro.com>,
	"daniel-gl@....net" <daniel-gl@....net>,
	"rmallon@...il.com" <rmallon@...il.com>, "sr@...x.de" <sr@...x.de>,
	"wg@...ndegger.com" <wg@...ndegger.com>
Subject: Re: [PATCH RESEND 5/6 v10] gpio: Add device tree support to block
 GPIO API

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.

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
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