linux-kernel - Re: [PATCHv6 1/8] zsmalloc: add to mm/

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20130221144430.2d3d77fc.akpm@linux-foundation.org>
Date:	Thu, 21 Feb 2013 14:44:30 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Seth Jennings <sjenning@...ux.vnet.ibm.com>
Cc:	Cody P Schafer <cody@...ux.vnet.ibm.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Nitin Gupta <ngupta@...are.org>,
	Minchan Kim <minchan@...nel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Dan Magenheimer <dan.magenheimer@...cle.com>,
	Robert Jennings <rcj@...ux.vnet.ibm.com>,
	Jenifer Hopper <jhopper@...ibm.com>,
	Mel Gorman <mgorman@...e.de>,
	Johannes Weiner <jweiner@...hat.com>,
	Rik van Riel <riel@...hat.com>,
	Larry Woodman <lwoodman@...hat.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Joe Perches <joe@...ches.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org
Subject: Re: [PATCHv6 1/8] zsmalloc: add to mm/

On Thu, 21 Feb 2013 16:21:37 -0600
Seth Jennings <sjenning@...ux.vnet.ibm.com> wrote:

> On 02/21/2013 02:36 PM, Cody P Schafer wrote:
> > On Wed, Feb 20, 2013 at 04:04:41PM -0600, Seth Jennings wrote:
> >> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> >> +#define MAX(a, b) ((a) >= (b) ? (a) : (b))
> >> +/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
> >> +#define ZS_MIN_ALLOC_SIZE \
> >> +	MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
> > 
> > Could you use the max(a,b) defined in include/linux/kernel.h?
> > 
> 
> Andrew Morton made the same point.  We can't use max() or max_t()
> because the value of ZS_MIN_ALLOC_SIZE is used to derive the value of
> ZS_SIZE_CLASSES which is used to size an array in struct zs_pool.
> 
> So the expression must be completely evaluated to a number by the
> precompiler.

Well yes, but the kernel doesn't need eight(!) separate
implementations of

#define MAX(a, b) ((a) > (b) ? (a) : (b))
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/