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From: Yoann Padioleau <padator@wanadoo.fr>
To: kernel-janitors@vger.kernel.org
Subject: Re: [KJ] question on double cast
Date: Tue, 22 May 2007 12:15:13 +0000	[thread overview]
Message-ID: <873b1p2gxa.fsf@wanadoo.fr> (raw)
In-Reply-To: <87y7jh4669.fsf@wanadoo.fr>

"John Anthony Kazos Jr." <jakj@j-a-k-j.com> writes:

>> In drivers/infiniband/hw/amso1100/c2_cm.c", line 321
>> there is
>> 
>>  	wr->ep_handle = (u32) (unsigned long) cm_id->provider_data;
>> 
>> What is the goal of this double cast ? There are plenty of
>> such double cast in the kernel.
>
> provider_data is type "void *", so presumably the object it points to is 
> of type [un]signed long (meaning its size differs on different 
> architectures). It is being cast to unsigned long to set it to that size 
> with no sign bits, and then the low-order 32 bits are being chopped off.

But isn't it equivalent to directly do 

  wr->ep_handle = (u32) cm_id->provider_data;

? 




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  parent reply	other threads:[~2007-05-22 12:15 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-22  8:24 [KJ] question on double cast Yoann Padioleau
2007-05-22 11:44 ` John Anthony Kazos Jr.
2007-05-22 12:15 ` Yoann Padioleau [this message]
2007-05-22 12:52 ` John Anthony Kazos Jr.
2007-05-22 12:54 ` Matthew Wilcox
2007-05-22 13:44 ` Matthew Wilcox

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