linux-kernel - Re: [PATCH 05/12] mm: alloc_contig

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Message-ID: <op.vs7umufd3l0zgt@mnazarewicz-glaptop>
Date:	Thu, 31 Mar 2011 18:26:45 +0200
From:	"Michal Nazarewicz" <mina86@...a86.com>
To:	"Marek Szyprowski" <m.szyprowski@...sung.com>,
	"Dave Hansen" <dave@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, linux-media@...r.kernel.org,
	linux-mm@...ck.org, "Kyungmin Park" <kyungmin.park@...sung.com>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>,
	"Ankita Garg" <ankita@...ibm.com>,
	"Daniel Walker" <dwalker@...eaurora.org>,
	"Johan MOSSBERG" <johan.xx.mossberg@...ricsson.com>,
	"Mel Gorman" <mel@....ul.ie>, "Pawel Osciak" <pawel@...iak.com>
Subject: Re: [PATCH 05/12] mm: alloc_contig_range() added

> On Thu, 2011-03-31 at 15:16 +0200, Marek Szyprowski wrote:
>> +       ret = 0;
>> +       while (!PageBuddy(pfn_to_page(start & (~0UL << ret))))
>> +               if (WARN_ON(++ret >= MAX_ORDER))
>> +                       return -EINVAL;

On Thu, 31 Mar 2011 18:02:41 +0200, Dave Hansen wrote:
> Holy cow, that's dense.  Is there really no more straightforward way to
> do that?

Which part exactly is dense?  What would be qualify as a more
straightforward way?

> In any case, please pull the ++ret bit out of the WARN_ON().  Some
> people like to do:
>
> #define WARN_ON(...) do{}while(0)
>
> to save space on some systems.

I don't think that's the case.  Even if WARN_ON() decides not to print
a warning, it will still return the value of the argument.  If not,
a lot of code will brake.

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michal "mina86" Nazarewicz    (o o)
ooo +-----<email/xmpp: mnazarewicz@...gle.com>-----ooO--(_)--Ooo--
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