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Date: Wed, 12 Jul 2006 00:22:55 -0700 (PDT)
Message-Id: <20060712.002255.45063957.davem@davemloft.net>
To: kaos@ocs.com.au
Cc: linux-kernel@vger.kernel.org
Subject: Re: sparse annotation question 
From: David Miller <davem@davemloft.net>
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From: Keith Owens <kaos@ocs.com.au>
Date: Wed, 12 Jul 2006 16:42:44 +1000

> I tried various combinations of __force, but kept getting this:
> 
> warning: incorrect type in argument 1 (different address spaces)
>    expected unsigned long *addr
>    got unsigned long [noderef] [force] *[addressable] bsp<asn:1>
> 
> What finally worked was
> 
>  	unsigned long i, *bsp, __user *ubsp;
> 	...
> 	ubsp = (unsigned long __user *) bsp;
> 	put_user(*contents, ubsp);
> 

Right, I guess if you try to do the cast in the put_user() macro
argument, you'll run into troubles because the __chk_user_ptr(ptr)
call wants an absolutely pure __user pointer, not one that is part of
a __force cast.