Re: [PATCH] applicom: Prevent unsigned wrap in ac_interrupt()

[Jiri Slaby <jirislaby@gmail.com>]

On 08/08/2009 05:13 PM, Roel Kluin wrote:
> unsigned i wraps if this occurs in the first iteration.

Could you elaborate? I don't quite understand the point.

> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
> Or do we know this can't happen?

You mean the i--? It's followed by i++ in the for loop 3rd expression. Or?

> 
> diff --git a/drivers/char/applicom.c b/drivers/char/applicom.c
> index 73a0765..0df3e12 100644
> --- a/drivers/char/applicom.c
> +++ b/drivers/char/applicom.c
> @@ -670,7 +670,7 @@ static irqreturn_t ac_interrupt(int vec, void *dev_instance)
>  			}
>  			Dummy = readb(apbs[i].RamIO + VERS);
>  
> -			if(readb(apbs[i].RamIO + RAM_IT_TO_PC)) {
> +			if(i && readb(apbs[i].RamIO + RAM_IT_TO_PC)) {
>  				/* There's another int waiting on this card */
>  				spin_unlock(&apbs[i].mutex);
>  				i--;