linux-kernel - Re: [PATCH 1/2] btree: Fix tree corruption in btree_get

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Message-ID: <CAG4TOxNwVYPPP_AL=YZ6LnZZWyp8FUa50aGtgqGjTwnu598-Lw@mail.gmail.com>
Date:	Wed, 6 Jun 2012 17:44:20 -0700
From:	Roland Dreier <roland@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Joern Engel <joern@...fs.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] btree: Fix tree corruption in btree_get_prev()

On Wed, Jun 6, 2012 at 4:36 PM, Roland Dreier <roland@...nel.org> wrote:
> On the other hand, your change makes me think we don't
> even need a separate iterator (and we can avoid the variable
> length array declaration)

FWIW with that change on top of my patch, I see

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-123 (-123)
function                                     old     new   delta
btree_get_prev                               646     523    -123

on x86-64, so avoiding the variable length array is definitely
worth something.

So the issue for me is whether messing with the caller's
__key storage is OK, or if it's worth having a temporary
local variable.

 - R.
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