linux-kernel - Re: [PATCH 1/2] gpio: Fix crash in gpiod_set

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Date:	Tue, 03 Sep 2013 14:25:52 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Thierry Reding <thierry.reding@...il.com>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] gpio: Fix crash in gpiod_set_debounce()

On 09/03/2013 04:39 AM, Thierry Reding wrote:
> Return an error if neither the ->set() nor the ->set_debounce() function
> is implemented by the chip. Furthermore move locking further down so the
> lock doesn't have to be unlocked on error. This is safe to do because at
> this point the lock doesn't protect anything.

> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c

>  	chip = desc->chip;
>  	if (!chip->set || !chip->set_debounce) {
>  	  pr_warn("%s: missing set() or set_debounce() operations\n",
>  		  __func__);
> +		return -EIO;
>  	}

BTW, I'm not sure that error-path should pr_warn(). For example, if this
error-patch is taken due to a call from
gpio_keys.c:gpio_keys_setup_key(), then a timer will be used for
debounce instead, which is all perfectly valid, and probably not
something that should be spewed to the kernel log.
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