From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3D9CC43142 for ; Tue, 31 Jul 2018 05:27:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 829F3208A2 for ; Tue, 31 Jul 2018 05:27:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 829F3208A2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lge.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728035AbeGaHE1 (ORCPT ); Tue, 31 Jul 2018 03:04:27 -0400 Received: from lgeamrelo13.lge.com ([156.147.23.53]:50872 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726917AbeGaHE1 (ORCPT ); Tue, 31 Jul 2018 03:04:27 -0400 Received: from unknown (HELO lgeamrelo04.lge.com) (156.147.1.127) by 156.147.23.53 with ESMTP; 31 Jul 2018 14:25:58 +0900 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: byungchul.park@lge.com Received: from unknown (HELO X58A-UD3R) (10.177.222.33) by 156.147.1.127 with ESMTP; 31 Jul 2018 14:25:58 +0900 X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Tue, 31 Jul 2018 14:25:51 +0900 From: Byungchul Park To: "Huang, Ying" Cc: linux-kernel@vger.kernel.org, kernel-team@lge.com, peterz@infradead.org, mingo@kernel.org, jiangshanlai@gmail.com, paulmck@linux.vnet.ibm.com, josh@joshtriplett.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, joel@joelfernandes.org, len.brown@intel.com, glider@google.com, peter@hurleysoftware.com, aik@ozlabs.ru Subject: Re: [QUESTION] llist: Comment releasing 'must delete' restriction before traversing Message-ID: <20180731052551.GA12241@X58A-UD3R> References: <1532998716-5037-1-git-send-email-byungchul.park@lge.com> <87d0v4mbgx.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d0v4mbgx.fsf@yhuang-dev.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 31, 2018 at 09:37:50AM +0800, Huang, Ying wrote: > Byungchul Park writes: > > > Hello folks, > > > > I'm careful in saying.. and curious about.. > > > > In restrictive cases like only addtions happen but never deletion, can't > > we safely traverse a llist? I believe llist can be more useful if we can > > release the restriction. Can't we? > > > > If yes, we may add another function traversing starting from a head. Or > > just use existing funtion with head->first. > > > > Thank a lot for your answers in advance :) > > What's the use case? I don't know how it is useful that items are never > deleted from the llist. > > Some other locks could be used to provide mutual exclusive between > > - llist add, llist traverse Hello Huang, In my use case, I only do adding and traversing on a llist. > > and > > - llist delete Of course, I will use a lock when deletion is needed. So.. in the case only adding into and traversing a llist is needed, can't we safely traverse a llist in the way I thought? Or am I missing something? Thank you. > Is this your use case? > > Best Regards, > Huang, Ying