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From: Michael Buesch <mb@bu3sch.de>
To: Mariusz Kozlowski <m.kozlowski@tuxland.pl>
Subject: Re: orinoco driver question
Date: Sat, 4 Nov 2006 22:04:57 +0100
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On Friday 03 November 2006 16:13, Mariusz Kozlowski wrote:
> Hi there,
> 
> 	Hope that's not a problem to ask some 'newbie' kernel coding stuff here. Here 
> it goes:
> 
> There are those two orinoco ioctl's
> 
> - orinoco_ioctl_setport3
> - orinoco_ioctl_getport3
> 
> Both take 'char *extra' as an argument to set/get 'priv->prefer_port3'. The 
> argument value to orinoco_ioctl_setport3 can be either 0 (IEEE ad-hoc mode) 
> or 1 (Lucent proprietary ad-hoc mode) the rest is -EINVAL. I don't get why 
> there is a need for an extra 'int' variable and casts in the code. 
> Using 'char *extra' seems to be fine there. To visualize what I mean here is 
> the patch:
> 
> --- linux-2.6.19-rc4-orig/drivers/net/wireless/orinoco.c        2006-11-02 
> 23:52:39.000000000 +0100
> +++ linux-2.6.19-rc4/drivers/net/wireless/orinoco.c     2006-11-03 
> 16:02:45.000000000 +0100
> @@ -3658,14 +3658,13 @@ static int orinoco_ioctl_setport3(struct
>                                   char *extra)
>  {
>         struct orinoco_private *priv = netdev_priv(dev);
> -       int val = *( (int *) extra );
>         int err = 0;
>         unsigned long flags;
>  
>         if (orinoco_lock(priv, &flags) != 0)
>                 return -EBUSY;
>  
> -       switch (val) {
> +       switch (*extra) {
>         case 0: /* Try to do IEEE ad-hoc mode */
>                 if (! priv->has_ibss) {
>                         err = -EINVAL;
> @@ -3704,9 +3703,8 @@ static int orinoco_ioctl_getport3(struct
>                                   char *extra)
>  {
>         struct orinoco_private *priv = netdev_priv(dev);
> -       int *val = (int *) extra;
>  
> -       *val = priv->prefer_port3;
> +       *extra = (char)priv->prefer_port3;
>         return 0;
>  }
> 
> I don't think this patch decreases code readability. This is just an example 
> but if there are more functions like this doesn't removing 'redundant' (?) 
> variables make the code better?

This breaks on bigendian systems.

-- 
Greetings Michael.