Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965793Ab2EOCVF (ORCPT ); Mon, 14 May 2012 22:21:05 -0400 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:58524 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965430Ab2EOCVB (ORCPT ); Mon, 14 May 2012 22:21:01 -0400 X-AuditID: 9c930197-b7be2ae000000ebb-26-4fb1bd8adda1 Message-ID: <4FB1BDAB.7090609@kernel.org> Date: Tue, 15 May 2012 11:21:31 +0900 From: Minchan Kim User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120410 Thunderbird/11.0.1 MIME-Version: 1.0 Newsgroups: gmane.linux.kernel.mm,gmane.linux.kernel To: Nitin Gupta CC: Konrad Rzeszutek Wilk , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] zsmalloc use zs_handle instead of void * References: <4FAB21E7.7020703@kernel.org> <20120510140215.GC26152@phenom.dumpdata.com> <4FABD503.4030808@vflare.org> <4FABDA9F.1000105@linux.vnet.ibm.com> <20120510151941.GA18302@kroah.com> <4FABECF5.8040602@vflare.org> <20120510164418.GC13964@kroah.com> <4FABF9D4.8080303@vflare.org> <20120510173322.GA30481@phenom.dumpdata.com> <4FAC4E3B.3030909@kernel.org> <20120511192831.GC3785@phenom.dumpdata.com> <4FB06B91.1080008@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1526 Lines: 47 On 05/15/2012 10:57 AM, Nitin Gupta wrote: >>> >>>> >>>> >>>>>> Its true that making it a real struct would prevent accidental casts >>>>>> to void * but due to the above problem, I think we have to stick >>>>>> with unsigned long. >>> >>> So the problem you are seeing is that you don't want 'struct zs_handle' >>> be present in the drivers/staging/zsmalloc/zsmalloc.h header file? >>> It looks like the proper place. >> >> >> No. What I want is to remove coupling zsallocator's handle with zram/zcache. >> They shouldn't know internal of handle and assume it's a pointer. >> >> If Nitin confirm zs_handle's format can never change in future, I prefer "unsigned long" Nitin suggested than (void *). >> It can prevent confusion that normal allocator's return value is pointer for address so the problem is easy. >> But I am not sure he can make sure it. >> > > zs_handle will always be an unsigned long so its better to just use > the same as return type. Okay. it makes problem very easy. > > Another alternative is to return 'struct zs_handle *' which can be > used as a 'void *' by zcache and as unsigned long by zsmalloc. > However, I see no good reason for preferring this over simple unsigned > long as the return type. Agreed. -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/