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From: Li Zefan <lizf@cn.fujitsu.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: linuxppc-dev@ozlabs.org,
	Andrew Morton <akpm@linux-foundation.org>,
	paulus@samba.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] POWERPC: don't cast a pointer to pointer of list_head
Date: Fri, 07 Dec 2007 13:05:30 +0800	[thread overview]
Message-ID: <4758D49A.8090908@cn.fujitsu.com> (raw)
In-Reply-To: <200712071507.10161.nickpiggin@yahoo.com.au>

Nick Piggin 写道:
> On Thursday 06 December 2007 20:33, Li Zefan wrote:
>> The casting is safe only when the list_head member is the
>> first member of the structure.
> 
> Even so, I don't think too safe :) It might technically work,
> but it could break more easily.
> 
> So even if you find places where list_head is the first member of
> a structure, it would be nice to explicitly use the list_head member
> and avoid casts IMO.
> 

This is exactly what I think. Those patches actually fix no bugs, but
avoid this kind of technically and currently correct casting.

> 
>> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
>>
>> ---
>>  arch/ppc/syslib/ocp.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/ppc/syslib/ocp.c b/arch/ppc/syslib/ocp.c
>> index 3f5be2c..d42d408 100644
>> --- a/arch/ppc/syslib/ocp.c
>> +++ b/arch/ppc/syslib/ocp.c
>> @@ -376,7 +376,7 @@ ocp_remove_one_device(unsigned int vendor, unsigned int
>> function, int index)
>>
>>  	down_write(&ocp_devices_sem);
>>  	dev = __ocp_find_device(vendor, function, index);
>> -	list_del((struct list_head *)dev);
>> +	list_del(&dev->link);
>>  	up_write(&ocp_devices_sem);
>>
>>  	DBG(("ocp: ocp_remove_one_device(vendor: %x, function: %x, index: %d)...
>> done.\n", vendor, function, index));
> 
> 

WARNING: multiple messages have this Message-ID (diff)
From: Li Zefan <lizf@cn.fujitsu.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: paulus@samba.org, LKML <linux-kernel@vger.kernel.org>,
	linuxppc-dev@ozlabs.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/3] POWERPC: don't cast a pointer to pointer of list_head
Date: Fri, 07 Dec 2007 13:05:30 +0800	[thread overview]
Message-ID: <4758D49A.8090908@cn.fujitsu.com> (raw)
In-Reply-To: <200712071507.10161.nickpiggin@yahoo.com.au>

Nick Piggin 写道:
> On Thursday 06 December 2007 20:33, Li Zefan wrote:
>> The casting is safe only when the list_head member is the
>> first member of the structure.
> 
> Even so, I don't think too safe :) It might technically work,
> but it could break more easily.
> 
> So even if you find places where list_head is the first member of
> a structure, it would be nice to explicitly use the list_head member
> and avoid casts IMO.
> 

This is exactly what I think. Those patches actually fix no bugs, but
avoid this kind of technically and currently correct casting.

> 
>> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
>>
>> ---
>>  arch/ppc/syslib/ocp.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/ppc/syslib/ocp.c b/arch/ppc/syslib/ocp.c
>> index 3f5be2c..d42d408 100644
>> --- a/arch/ppc/syslib/ocp.c
>> +++ b/arch/ppc/syslib/ocp.c
>> @@ -376,7 +376,7 @@ ocp_remove_one_device(unsigned int vendor, unsigned int
>> function, int index)
>>
>>  	down_write(&ocp_devices_sem);
>>  	dev = __ocp_find_device(vendor, function, index);
>> -	list_del((struct list_head *)dev);
>> +	list_del(&dev->link);
>>  	up_write(&ocp_devices_sem);
>>
>>  	DBG(("ocp: ocp_remove_one_device(vendor: %x, function: %x, index: %d)...
>> done.\n", vendor, function, index));
> 
> 



  reply	other threads:[~2007-12-07  5:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-06  9:33 [PATCH 1/3] POWERPC: don't cast a pointer to pointer of list_head Li Zefan
2007-12-06  9:33 ` Li Zefan
2007-12-07  4:07 ` Nick Piggin
2007-12-07  4:07   ` Nick Piggin
2007-12-07  5:05   ` Li Zefan [this message]
2007-12-07  5:05     ` Li Zefan

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