Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1945927Ab2EKSE2 (ORCPT ); Fri, 11 May 2012 14:04:28 -0400 Received: from mga14.intel.com ([143.182.124.37]:3592 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932096Ab2EKSEZ convert rfc822-to-8bit (ORCPT ); Fri, 11 May 2012 14:04:25 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="141975764" From: "Liu, Jinsong" To: Konrad Rzeszutek Wilk CC: "'xen-devel@lists.xensource.com'" , "'linux-kernel@vger.kernel.org'" Subject: RE: [PATCH 3/3] Xen physical cpus interface Thread-Topic: [PATCH 3/3] Xen physical cpus interface Thread-Index: AQHNLr1B1b8pDRiwSFiwkpXixs4X8JbDIYNQgAGHQueAADaqsA== Date: Fri, 11 May 2012 18:04:21 +0000 Message-ID: References: <20120420192439.GA32170@phenom.dumpdata.com> <20120510145745.GO26152@phenom.dumpdata.com> <20120511142758.GA29677@phenom.dumpdata.com> In-Reply-To: <20120511142758.GA29677@phenom.dumpdata.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2591 Lines: 76 Konrad Rzeszutek Wilk wrote: > On Fri, May 11, 2012 at 01:12:13PM +0000, Liu, Jinsong wrote: >> Liu, Jinsong wrote: >>> Just notice your reply (so quick :) >>> >>> Agree and will update later, except 1 concern below. >>> >>> Konrad Rzeszutek Wilk wrote: >>>>> >>>>> Hmm, it's good if it's convenient to do it automatically via >>>>> dev->release. However, dev container (pcpu) would be free at some >>>>> other error cases, so I prefer do it 'manually'. >>>> >>>> You could also call pcpu_release(..) to do it manually. >>>> >>> >>> that means kfree(pcpu) would be done twice at some error cases, do >>> you think it really good? >>> >> >> Ping. >> >> I think error recovery should be kept inside error logic level >> itself, if try to recover upper level error would bring trouble. >> >> In our example, there are 2 logic levels: >> pcpu level (as container), and dev level (subfield used for sys) > > So you need to untangle free_pcpu from doing both. Meaning one does > the SysFS and the other deals with free-ing the structure and > removing itself from the list. > free_cpu is very samll, just consist of the 2 parts your said: * pcpu_sys_remove() deal with sysfs * list_del/kfree(pcpu) deal with pcpu > >> dev->release should only recover error occurred at dev/sys level, >> and the pcpu error should be recovered at pcpu level. >> >> If dev->release try to recover its container pcpu level error, like >> list_del/kfree(pcpu), it would make confusing. i.e., considering >> pcpu_sys_create(), 2 error cases: device_register fail, and >> device_create_file fail --> how can the caller decide kfree(pcpu) or >> not? > > Then you should free it manually. But you can do this by a wrapper > function: > > __pcpu_release(..) { > .. > /* Does the removing itself from the list and kfree the pcpu */ > } > pcpu_release(..) { > struct pcpcu *p= container_of(..) > __pcpu_release(p); > } > > dev->release = &pcpu_release; > Too weird way. If we want to release dev itself it's good to use dev->release, but for pcpu I doubt it. (consider the example I gave --> why we create issue (it maybe solved in weird method I agree), just for using dev->release?) In kernel many dev->release keep NULL. An example of using dev->release is cpu/mcheck/mce.c --> mce_device_release(), it *just* deal dev itself. Thanks, Jinsong -- 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/