Re: [PATCH] gpio: Fix test on unsigned in lnw_irq_type()

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 12 Oct 2009 16:12:40 +0200
Roel Kluin <roel.kluin@gmail.com> wrote:

> The wrong test was used, gpio is unsigned.
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
> diff --git a/drivers/gpio/langwell_gpio.c b/drivers/gpio/langwell_gpio.c
> index 5711ce5..0d0cbc0 100644
> --- a/drivers/gpio/langwell_gpio.c
> +++ b/drivers/gpio/langwell_gpio.c
> @@ -123,8 +123,11 @@ static int lnw_irq_type(unsigned irq, unsigned type)
>  	void __iomem *grer = (void __iomem *)(&lnw->reg_base->GRER[reg]);
>  	void __iomem *gfer = (void __iomem *)(&lnw->reg_base->GFER[reg]);
>  
> -	if (gpio < 0 || gpio > lnw->chip.ngpio)
> +	if (irq < lnw->irq_base || gpio > lnw->chip.ngpio ||
> +			reg >= ARRAY_SIZE(lnw->reg_base->GRER)
> +			reg >= ARRAY_SIZE(lnw->reg_base->GFER))
>  		return -EINVAL;
> +
>  	spin_lock_irqsave(&lnw->lock, flags);
>  	if (type & IRQ_TYPE_EDGE_RISING)
>  		value = readl(grer) | BIT(gpio % 32);

Makes the code unfortunately complex.  It'd be better to make `gpio' a
signed quantity, or even..

--- a/drivers/gpio/langwell_gpio.c~gpio-fix-test-on-unsigned-in-lnw_irq_type
+++ a/drivers/gpio/langwell_gpio.c
@@ -123,7 +123,7 @@ static int lnw_irq_type(unsigned irq, un
 	void __iomem *grer = (void __iomem *)(&lnw->reg_base->GRER[reg]);
 	void __iomem *gfer = (void __iomem *)(&lnw->reg_base->GFER[reg]);
 
-	if (gpio < 0 || gpio > lnw->chip.ngpio)
+	if ((s32)gpio < 0 || gpio > lnw->chip.ngpio)
 		return -EINVAL;
 	spin_lock_irqsave(&lnw->lock, flags);
 	if (type & IRQ_TYPE_EDGE_RISING)
_