linux-kernel - Re: [PATCH] /dev/mem: Fix wrong error on accessing beyond valid memory addresses.

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Message-ID: <4EC19253.6080201@zytor.com>
Date:	Mon, 14 Nov 2011 14:12:35 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andrei Warkentin <awarkentin@...are.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] /dev/mem: Fix wrong error on accessing beyond valid memory
 addresses.

On 11/14/2011 02:11 PM, Andrei Warkentin wrote:
>>
>> EOF seems wrong to me (not as bad as EFAULT, but still wrong).
>
> Although that was what we had discussed, I do not return -EOF in the patch. As you
> mention - that would be wrong. I played around with other devices (block, actually),
> and if you attempt to read(2) beyond the end, read(2) simply returns 0, as in
> zero bytes read out. Of course, lseek(2) beyond the end should return -EINVAL, as
> well, so that is what that patch I CCd you on accomplishes.
>

0 is EOF.

This is not a block device -- comparing to block devices is pointless. 
There is no "end" to /dev/mem, so this is a totally meaningless comparison.

	-hpa

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