linux-kernel - Re: [PATCH 13/30] net: Don't do pointless kmalloc return value casts in zd1211 driver

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Message-Id: <E1IR2pW-0007T2-00@gondolin.me.apana.org.au>
Date:	Fri, 31 Aug 2007 17:30:18 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	jesper.juhl@...il.com (Jesper Juhl),
	Al Viro <viro@....linux.org.uk>
Cc:	dsd@...too.org, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, davem@...emloft.net, kune@...ne-taler.de,
	linux-wireless@...r.kernel.org
Subject: Re: [PATCH 13/30] net: Don't do pointless kmalloc return value casts in zd1211 driver

Jesper Juhl <jesper.juhl@...il.com> wrote:
> On 30/08/2007, Daniel Drake <dsd@...too.org> wrote:
>> Jesper Juhl wrote:
>> > Since kmalloc() returns a void pointer there is no reason to cast
>> > its return value.
>> > This patch also removes a pointless initialization of a variable.
>>
>> NAK: adds a sparse warning
>> zd_chip.c:116:15: warning: implicit cast to nocast type
>>
> 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?
> 
> I see it's defined as
>  typedef u32 __nocast zd_addr_t;
> in drivers/net/wireless/zd1211rw/zd_types.h , but why the __nocast ?

Nevermind the __nocast, this looks like a bug in sparse.  Just
because a base type is __nocast, sparse shouldn't infer that a
pointer to it should also be __nocast.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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