linux-kernel - Re: [PATCH 8/9] staging: panel: Remove more magic number comparison

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Message-ID: <20141118212523.GK26514@1wt.eu>
Date:	Tue, 18 Nov 2014 22:25:23 +0100
From:	Willy Tarreau <w@....eu>
To:	Mariusz Gorski <marius.gorski@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/9] staging: panel: Remove more magic number comparison

On Tue, Nov 18, 2014 at 09:56:13PM +0100, Mariusz Gorski wrote:
> Use a macro instead of magic number comparison for checking
> whether a module param value has been set.
> 
> Signed-off-by: Mariusz Gorski <marius.gorski@...il.com>
> ---
>  drivers/staging/panel/panel.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/staging/panel/panel.c b/drivers/staging/panel/panel.c
> index ee48bca..268ad2e 100644
> --- a/drivers/staging/panel/panel.c
> +++ b/drivers/staging/panel/panel.c
> @@ -136,6 +136,7 @@
>  #define NOT_SET			-1
>  
>  #define IS_NOT_SET(x)	(x == NOT_SET)
> +#define IS_SET(x)		(x > NOT_SET)
>  
>  /* macros to simplify use of the parallel port */
>  #define r_ctr(x)        (parport_read_control((x)->port))
> @@ -1496,17 +1497,17 @@ static void lcd_init(void)
>  	}
>  
>  	/* Overwrite with module params set on loading */
> -	if (lcd_height > -1)
> +	if (IS_SET(lcd_height))
>  		lcd.height = lcd_height;
> -	if (lcd_width > -1)
> +	if (IS_SET(lcd_width))
>  		lcd.width = lcd_width;

(...)

Same as for the other patch, better open-code the test for readability :

-	if (lcd_height > -1)
+	if (lcd_height != NOT_SET)
 		lcd.height = lcd_height;

Note that we take the freedom to change the operator since we only want
to check equality and not sign in practice.

Willy

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