linux-kernel - Re: [RFC] memblock; Properly handle overlaps

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Message-ID: <1299372594.8833.966.camel@pasglop>
Date:	Sun, 06 Mar 2011 11:49:54 +1100
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>, linux-mm@...ck.org,
	Russell King <linux@....linux.org.uk>
Subject: Re: [RFC] memblock; Properly handle overlaps

On Sat, 2011-03-05 at 15:20 -0800, Yinghai Lu wrote:
> 
> maybe we can omit rgn->size == 0 checking here.
> with that case, dummy array will go though to some extra checking.
> 
> if (rgn->base <= base && rend >= end)
> if (base < rgn->base && end >= rgn->base) {
> if (base <= rend && end >= rend) {
> 
> but we can spare more checking regarding
>         rgn->size == 0

Well, the array can be collasped to dummy by the removal of the last
block when doing a top overlap, then on the next loop around, we can
potentially hit the if (base <= rend && end >= rend) test, and loop
again no ?

I'd rather keep the test in .. won't hurt.

Cheers,
Ben.

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