netdev - Re: [PATCH] Don't needlessly initialize variable to NULL in zd_chip (was: Re: [PATCH 13/30] net: Don't do pointless kmalloc return value casts in zd1211 driver)

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Message-Id: <20070830154255.6a146c21.randy.dunlap@oracle.com>
Date:	Thu, 30 Aug 2007 15:42:55 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	Jesper Juhl <jesper.juhl@...il.com>
Cc:	Joe Perches <joe@...ches.com>, Daniel Drake <dsd@...too.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Ulrich Kunitz <kune@...ne-taler.de>,
	linux-wireless@...r.kernel.org
Subject: Re: [PATCH] Don't needlessly initialize variable to NULL in zd_chip
   (was: Re: [PATCH 13/30] net: Don't do pointless kmalloc return value
 casts in zd1211 driver)

On Fri, 31 Aug 2007 00:30:31 +0200 Jesper Juhl wrote:

> On Friday 31 August 2007 00:19:53 Joe Perches wrote:
> > On Thu, 2007-08-30 at 22:20 +0200, Jesper Juhl wrote:
> > > Ok, I must admit I didn't check with sparse since it seemed pointless
> > > - we usually never cast void pointers to other pointer types,
> > > specifically because the C language nicely guarantees that the right
> > > thing will happen without the cast.  Sometimes we have to cast them to
> > > integer types, su sure we need the cast there.   But what on earth
> > > makes a "zd_addr_t *" so special that we have to explicitly cast a
> > > "void *" to that type?
> > 
> > http://marc.info/?l=linux-netdev&m=117113743902549&w=1
> > 
> 
> Thank you for that link Joe.
> 
> I'm not sure I agree with the __nocast, but I respect that this is 
> the maintainers choice.
> 
> But, I still think the first chunk of the patch that removes the 
> initial variable initialization makes sense. 
> Initializing the variable to NULL is pointless since it'll never be
> used before the kmalloc() call. So here's a revised patch that just
> gets rid of that little detail.


BTW:  http://marc.info/?l=linux-wireless&m=118831813500769&w=2


> No need to initialize to NULL when variable is never used before 
> it's assigned the return value of a kmalloc() call.
> 
> Signed-off-by: Jesper Juhl <jesper.juhl@...il.com>
> ---
> 
> diff --git a/drivers/net/wireless/zd1211rw/zd_chip.c b/drivers/net/wireless/zd1211rw/zd_chip.c
> index c39f198..30872fe 100644
> --- a/drivers/net/wireless/zd1211rw/zd_chip.c
> +++ b/drivers/net/wireless/zd1211rw/zd_chip.c
> @@ -106,7 +106,7 @@ int zd_ioread32v_locked(struct zd_chip *chip, u32 *values, const zd_addr_t *addr
>  {
>  	int r;
>  	int i;
> -	zd_addr_t *a16 = (zd_addr_t *)NULL;
> +	zd_addr_t *a16;
>  	u16 *v16;
>  	unsigned int count16;


---
~Randy
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