linux-kernel - Re: [PATCH] kfifo: remove unnecessary type check

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Date:	Fri, 26 Oct 2012 07:38:31 +0200
From:	Stefani Seibold <stefani@...bold.net>
To:	Yuanhan Liu <yliu.null@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	Yuanhan Liu <yuanhan.liu@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Wei Yang <weiyang@...ux.vnet.ibm.com>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH] kfifo: remove unnecessary type check

Am Freitag, den 26.10.2012, 09:46 +0800 schrieb Yuanhan Liu:
> From: Yuanhan Liu <yuanhan.liu@...ux.intel.com>
> 
> Firstly, this kind of type check doesn't work. It does something similay
> like following:
> 	void * __dummy = NULL;
> 	__buf = __dummy;
> 
> __dummy is defined as void *. Thus it will not trigger warnings as
> expected.
> 
> Second, we don't need that kind of check. Since the prototype
> of __kfifo_out is:
> 	unsigned int __kfifo_out(struct __kfifo *fifo,  void *buf, unsigned int len)
> 
> buf is defined as void *, so we don't need do the type check. Remove it.
> 
> LINK: https://lkml.org/lkml/2012/10/25/386
> LINK: https://lkml.org/lkml/2012/10/25/584
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Wei Yang <weiyang@...ux.vnet.ibm.com>
> Cc: Stefani Seibold <stefani@...bold.net>
> Cc: Fengguang Wu <fengguang.wu@...el.com>
> Cc: Stephen Rothwell <sfr@...b.auug.org.au>
> Signed-off-by: Yuanhan Liu <yuanhan.liu@...ux.intel.com>
> ---
>  include/linux/kfifo.h | 20 --------------------
>  1 file changed, 20 deletions(-)
> 
> diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h
> index 10308c6..b8c1d03 100644
> --- a/include/linux/kfifo.h
> +++ b/include/linux/kfifo.h
> @@ -390,10 +390,6 @@ __kfifo_int_must_check_helper( \
>  	unsigned int __ret; \
>  	const size_t __recsize = sizeof(*__tmp->rectype); \
>  	struct __kfifo *__kfifo = &__tmp->kfifo; \
> -	if (0) { \
> -		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
> -		__dummy = (typeof(__val))NULL; \
> -	} \
>  	if (__recsize) \
>  		__ret = __kfifo_in_r(__kfifo, __val, sizeof(*__val), \
>  			__recsize); \
> @@ -432,8 +428,6 @@ __kfifo_uint_must_check_helper( \
>  	unsigned int __ret; \
>  	const size_t __recsize = sizeof(*__tmp->rectype); \
>  	struct __kfifo *__kfifo = &__tmp->kfifo; \
> -	if (0) \
> -		__val = (typeof(__tmp->ptr))0; \
>  	if (__recsize) \
>  		__ret = __kfifo_out_r(__kfifo, __val, sizeof(*__val), \
>  			__recsize); \
> @@ -473,8 +467,6 @@ __kfifo_uint_must_check_helper( \
>  	unsigned int __ret; \
>  	const size_t __recsize = sizeof(*__tmp->rectype); \
>  	struct __kfifo *__kfifo = &__tmp->kfifo; \
> -	if (0) \
> -		__val = (typeof(__tmp->ptr))NULL; \
>  	if (__recsize) \
>  		__ret = __kfifo_out_peek_r(__kfifo, __val, sizeof(*__val), \
>  			__recsize); \
> @@ -512,10 +504,6 @@ __kfifo_uint_must_check_helper( \
>  	unsigned long __n = (n); \
>  	const size_t __recsize = sizeof(*__tmp->rectype); \
>  	struct __kfifo *__kfifo = &__tmp->kfifo; \
> -	if (0) { \
> -		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
> -		__dummy = (typeof(__buf))NULL; \
> -	} \
>  	(__recsize) ?\
>  	__kfifo_in_r(__kfifo, __buf, __n, __recsize) : \
>  	__kfifo_in(__kfifo, __buf, __n); \
> @@ -565,10 +553,6 @@ __kfifo_uint_must_check_helper( \
>  	unsigned long __n = (n); \
>  	const size_t __recsize = sizeof(*__tmp->rectype); \
>  	struct __kfifo *__kfifo = &__tmp->kfifo; \
> -	if (0) { \
> -		typeof(__tmp->ptr) __dummy = NULL; \
> -		__buf = __dummy; \
> -	} \
>  	(__recsize) ?\
>  	__kfifo_out_r(__kfifo, __buf, __n, __recsize) : \
>  	__kfifo_out(__kfifo, __buf, __n); \
> @@ -777,10 +761,6 @@ __kfifo_uint_must_check_helper( \
>  	unsigned long __n = (n); \
>  	const size_t __recsize = sizeof(*__tmp->rectype); \
>  	struct __kfifo *__kfifo = &__tmp->kfifo; \
> -	if (0) { \
> -		typeof(__tmp->ptr) __dummy __attribute__ ((unused)) = NULL; \
> -		__buf = __dummy; \
> -	} \
>  	(__recsize) ? \
>  	__kfifo_out_peek_r(__kfifo, __buf, __n, __recsize) : \
>  	__kfifo_out_peek(__kfifo, __buf, __n); \

Did you tried to compile the whole kernel including all the drivers with
your patch?


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