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Date: Tue, 29 Apr 2008 16:04:56 +0800 (CST)
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To: Jeff Dike <jdike@addtoit.com>
cc: WANG Cong <xiyou.wangcong@gmail.com>, akpm@osdl.org,
       linux-kernel@vger.kernel.org,
       user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [PATCH 6/19] UML - hppfs fixes
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References: <20080425175608.GA11182@c2.user-mode-linux.org> <20080426.163132.194697674.xiyou.wangcong@gmail.com> <20080428152940.GA7465@c2.user-mode-linux.org>
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From: WANG Cong <xiyou.wangcong@gmail.com>
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On Mon, 28 Apr 2008, Jeff Dike wrote:

> On Sat, Apr 26, 2008 at 04:31:32PM +0800, WANG Cong wrote:
>> > +		rem = copy_to_user(buf, &data->contents[off], count);
>> > +		*ppos += count - rem;
>> > +		if (rem > 0)
>> > +			return -EFAULT;
>> 
>> Could you please explain why check 'rem' after using it here?
>
> Actually, this isn't as wrong as it looks. copy_to_user returns what
> hasn't been copied (rem == remaining).  So, I think the mistake is to
> return -EFAULT here.  Returning the short count would be right, unless
> rem == count, in which case we return -EFAULT.

Yes, thanks.

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