linux-kernel - Re: [PATCH 6/19] UML

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Message-ID: <20080428152940.GA7465@c2.user-mode-linux.org>
Date:	Mon, 28 Apr 2008 11:29:40 -0400
From:	Jeff Dike <jdike@...toit.com>
To:	WANG Cong <xiyou.wangcong@...il.com>
Cc:	akpm@...l.org, linux-kernel@...r.kernel.org,
	user-mode-linux-devel@...ts.sourceforge.net
Subject: Re: [PATCH 6/19] UML - hppfs fixes

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.

       	      	 Jeff

-- 
Work email - jdike at linux dot intel dot com
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