Re: [PATCH] gpiolib: Fix off by one errors

[David Brownell <david-b@pacbell.net>]

On Tuesday 20 May 2008, Trent Piepho wrote:
> The last gpio belonging to a chip is chip->base + chip->ngpios - 1.  Some
> places in the code, but not all, forgot the critical minus one.
> 
> Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>

Acked-by: David Brownell <dbrownell@users.sourceforge.net>

... should make it into 2.6.26-final, but this is evidently
not critical at this point or we'd have had complaints already!


> ---
>  drivers/gpio/gpiolib.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 7f138c6..beaf6b3 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -127,7 +127,7 @@ int __init gpiochip_reserve(int start, int ngpio)
>  	unsigned long flags;
>  	int i;
>  
> -	if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio))
> +	if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
>  		return -EINVAL;
>  
>  	spin_lock_irqsave(&gpio_lock, flags);
> @@ -170,7 +170,7 @@ int gpiochip_add(struct gpio_chip *chip)
>  	unsigned	id;
>  	int		base = chip->base;
>  
> -	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio))
> +	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
>  			&& base >= 0) {
>  		status = -EINVAL;
>  		goto fail;
> @@ -207,7 +207,7 @@ fail:
>  	/* failures here can mean systems won't boot... */
>  	if (status)
>  		pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
> -			chip->base, chip->base + chip->ngpio,
> +			chip->base, chip->base + chip->ngpio - 1,
>  			chip->label ? : "generic");
>  	return status;
>  }
> -- 
> 1.5.4.1
>