From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Fri, 15 Nov 2013 14:26:53 +0000 Subject: [Cluster-devel] [PATCH 0/6] list: introduce list_last_entry_or_null() In-Reply-To: <20131115141100.GA17659@infradead.org> References: <5285A33C.4040808@oracle.com> <20131115141100.GA17659@infradead.org> Message-ID: <1384525613.2747.60.camel@menhir> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, On Fri, 2013-11-15 at 06:11 -0800, Christoph Hellwig wrote: > On Fri, Nov 15, 2013 at 12:29:48PM +0800, Jeff Liu wrote: > > Hi Folks, > > > > This patch is trying to introduce a new list helper to retrieve the > > last entry or return NULL if the list is empty corresponding to it, > > which is inspired by Jiri Pirko's list_first_entry_or_null(). > > How did we end up with the stupid _or_null prefix there? I think the > functionality is useful, but the naming is way to verbose, especially > given that a list_first_entry or list_last_entry that optimizes away > that one check doesn't seem useful. > > Instead of encoding detailed semantics in the name a good kerneldoc > comment is way better. > Also, in two of the cases (patch 3 and patch 6) we don't want NULL in the case that the list is empty, and instead want another pointer which, after the patches, requires an extra "if". Now I suspect that the optimizer will sort that out (I've not checked) so its probably not too big an issue. However, if instead of returning NULL for list empty, we had an extra argument to the function, then it could return whatever pointer was required for each case, whether NULL or otherwise, Steve. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com ([209.132.183.28]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VhKNW-0000sw-Pt for linux-mtd@lists.infradead.org; Fri, 15 Nov 2013 14:28:11 +0000 Subject: Re: [Cluster-devel] [PATCH 0/6] list: introduce list_last_entry_or_null() From: Steven Whitehouse To: Christoph Hellwig In-Reply-To: <20131115141100.GA17659@infradead.org> References: <5285A33C.4040808@oracle.com> <20131115141100.GA17659@infradead.org> Content-Type: text/plain; charset="UTF-8" Date: Fri, 15 Nov 2013 14:26:53 +0000 Message-ID: <1384525613.2747.60.camel@menhir> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: jfs-discussion@lists.sourceforge.net, jiri@resnulli.us, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, "xfs@oss.sgi.com" , cluster-devel@redhat.com, Jeff Liu , linux-mtd@lists.infradead.org, oleg@redhat.com, akpm@linux-foundation.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, On Fri, 2013-11-15 at 06:11 -0800, Christoph Hellwig wrote: > On Fri, Nov 15, 2013 at 12:29:48PM +0800, Jeff Liu wrote: > > Hi Folks, > > > > This patch is trying to introduce a new list helper to retrieve the > > last entry or return NULL if the list is empty corresponding to it, > > which is inspired by Jiri Pirko's list_first_entry_or_null(). > > How did we end up with the stupid _or_null prefix there? I think the > functionality is useful, but the naming is way to verbose, especially > given that a list_first_entry or list_last_entry that optimizes away > that one check doesn't seem useful. > > Instead of encoding detailed semantics in the name a good kerneldoc > comment is way better. > Also, in two of the cases (patch 3 and patch 6) we don't want NULL in the case that the list is empty, and instead want another pointer which, after the patches, requires an extra "if". Now I suspect that the optimizer will sort that out (I've not checked) so its probably not too big an issue. However, if instead of returning NULL for list empty, we had an extra argument to the function, then it could return whatever pointer was required for each case, whether NULL or otherwise, Steve. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 79F367F7B for ; Fri, 15 Nov 2013 08:28:20 -0600 (CST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay1.corp.sgi.com (Postfix) with ESMTP id 462058F8064 for ; Fri, 15 Nov 2013 06:28:20 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id ifg5zeURrhTPxiZB for ; Fri, 15 Nov 2013 06:28:19 -0800 (PST) Subject: Re: [Cluster-devel] [PATCH 0/6] list: introduce list_last_entry_or_null() From: Steven Whitehouse In-Reply-To: <20131115141100.GA17659@infradead.org> References: <5285A33C.4040808@oracle.com> <20131115141100.GA17659@infradead.org> Date: Fri, 15 Nov 2013 14:26:53 +0000 Message-ID: <1384525613.2747.60.camel@menhir> Mime-Version: 1.0 List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: jfs-discussion@lists.sourceforge.net, jiri@resnulli.us, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, "xfs@oss.sgi.com" , cluster-devel@redhat.com, Jeff Liu , linux-mtd@lists.infradead.org, oleg@redhat.com, akpm@linux-foundation.org Hi, On Fri, 2013-11-15 at 06:11 -0800, Christoph Hellwig wrote: > On Fri, Nov 15, 2013 at 12:29:48PM +0800, Jeff Liu wrote: > > Hi Folks, > > > > This patch is trying to introduce a new list helper to retrieve the > > last entry or return NULL if the list is empty corresponding to it, > > which is inspired by Jiri Pirko's list_first_entry_or_null(). > > How did we end up with the stupid _or_null prefix there? I think the > functionality is useful, but the naming is way to verbose, especially > given that a list_first_entry or list_last_entry that optimizes away > that one check doesn't seem useful. > > Instead of encoding detailed semantics in the name a good kerneldoc > comment is way better. > Also, in two of the cases (patch 3 and patch 6) we don't want NULL in the case that the list is empty, and instead want another pointer which, after the patches, requires an extra "if". Now I suspect that the optimizer will sort that out (I've not checked) so its probably not too big an issue. However, if instead of returning NULL for list empty, we had an extra argument to the function, then it could return whatever pointer was required for each case, whether NULL or otherwise, Steve. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752983Ab3KOO20 (ORCPT ); Fri, 15 Nov 2013 09:28:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:65438 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751626Ab3KOO2U (ORCPT ); Fri, 15 Nov 2013 09:28:20 -0500 Subject: Re: [Cluster-devel] [PATCH 0/6] list: introduce list_last_entry_or_null() From: Steven Whitehouse To: Christoph Hellwig Cc: Jeff Liu , jfs-discussion@lists.sourceforge.net, jiri@resnulli.us, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, "xfs@oss.sgi.com" , cluster-devel@redhat.com, linux-mtd@lists.infradead.org, oleg@redhat.com, akpm@linux-foundation.org In-Reply-To: <20131115141100.GA17659@infradead.org> References: <5285A33C.4040808@oracle.com> <20131115141100.GA17659@infradead.org> Content-Type: text/plain; charset="UTF-8" Organization: Red Hat UK Ltd Date: Fri, 15 Nov 2013 14:26:53 +0000 Message-ID: <1384525613.2747.60.camel@menhir> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, 2013-11-15 at 06:11 -0800, Christoph Hellwig wrote: > On Fri, Nov 15, 2013 at 12:29:48PM +0800, Jeff Liu wrote: > > Hi Folks, > > > > This patch is trying to introduce a new list helper to retrieve the > > last entry or return NULL if the list is empty corresponding to it, > > which is inspired by Jiri Pirko's list_first_entry_or_null(). > > How did we end up with the stupid _or_null prefix there? I think the > functionality is useful, but the naming is way to verbose, especially > given that a list_first_entry or list_last_entry that optimizes away > that one check doesn't seem useful. > > Instead of encoding detailed semantics in the name a good kerneldoc > comment is way better. > Also, in two of the cases (patch 3 and patch 6) we don't want NULL in the case that the list is empty, and instead want another pointer which, after the patches, requires an extra "if". Now I suspect that the optimizer will sort that out (I've not checked) so its probably not too big an issue. However, if instead of returning NULL for list empty, we had an extra argument to the function, then it could return whatever pointer was required for each case, whether NULL or otherwise, Steve.