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From: Arnd Bergmann <arnd@arndb.de>
To: will_schmidt@vnet.ibm.com
Subject: Re: [PATCH 2/3] spufs: fix another off-by-one bug in mbox_read
Date: Tue, 24 Oct 2006 21:58:32 +0200
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Cc: linuxppc-dev@ozlabs.org, Pekka Enberg <penberg@cs.helsinki.fi>,
	Paul Mackerras <paulus@samba.org>, cbe-oss-dev@ozlabs.org,
	linux-kernel@vger.kernel.org
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On Tuesday 24 October 2006 21:53, Will Schmidt wrote:
> Hey Arnd,
> =C2=A0 =C2=A0just curiosity.. =C2=A0 What was the behavior before this pa=
tch? =C2=A0 just
> leaving a few (0 - 3) characters behind?

It transfers more bytes than requested on a read. If you asked for
four bytes, you got eight.

Note: one nasty property of this file in spufs is that you can only
read multiples of four bytes in the first place, there is no way to
atomically put back a few bytes into the hardware register, so reading
less than four bytes returns -EINVAL. Asking for more than four
should return the largest possible multiple of four.

	Arnd <><