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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 CF82FC43441 for ; Mon, 12 Nov 2018 14:07:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87F6B223DD for ; Mon, 12 Nov 2018 14:07:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="a+ql0PFF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 87F6B223DD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=efficios.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 S1729749AbeKMABS (ORCPT ); Mon, 12 Nov 2018 19:01:18 -0500 Received: from mail.efficios.com ([167.114.142.138]:47998 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727103AbeKMABS (ORCPT ); Mon, 12 Nov 2018 19:01:18 -0500 Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 827CB238972; Mon, 12 Nov 2018 09:07:51 -0500 (EST) Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10032) with ESMTP id BpKjrrEUl27O; Mon, 12 Nov 2018 09:07:50 -0500 (EST) Received: from localhost (ip6-localhost [IPv6:::1]) by mail.efficios.com (Postfix) with ESMTP id 8C526238969; Mon, 12 Nov 2018 09:07:50 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 8C526238969 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1542031670; bh=X7AGNmctA5QMRd+GNzVJIazoxttgMWPkCHXlyaGPfFY=; h=Date:From:To:Message-ID:MIME-Version; b=a+ql0PFF1nYBBF6avk0paPYNZ2ZWSmePUHARoyKkdbHZtFF66Su6DFgpF7R1QhwNf k7KtlzypICUoM7DpT/FVpNXFPBu7EI19u9b57VIgItLrDxofUaHl7pj+3ldkt46DZy K6sgJoKZSzXrCLVejOu33p2auQzElLsCpffdSmagCL/FyVz8gizVZVCDTKJ68xWdm0 jzhnlVYrmmPI0vcQ5ZyKILVRLm8WYBH5OYOq6grbX0lVh2gDIrn0Syzn6naqTyYkSn Xe9C3iyzD4Wav9HTTW0oLTQKif3WozI/yrBhZAvU75yqNwy6IXjr6SKOxebooBYmXL Kb1dfWt4U3ysQ== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([IPv6:::1]) by localhost (mail02.efficios.com [IPv6:::1]) (amavisd-new, port 10026) with ESMTP id LRjxCb_-ZzGM; Mon, 12 Nov 2018 09:07:50 -0500 (EST) Received: from mail02.efficios.com (mail02.efficios.com [167.114.142.138]) by mail.efficios.com (Postfix) with ESMTP id 6D730238962; Mon, 12 Nov 2018 09:07:50 -0500 (EST) Date: Mon, 12 Nov 2018 09:07:50 -0500 (EST) From: Mathieu Desnoyers To: paulmck Cc: linux-kernel , Ingo Molnar , Lai Jiangshan , dipankar , Andrew Morton , Josh Triplett , Thomas Gleixner , Peter Zijlstra , rostedt , David Howells , Eric Dumazet , fweisbec , Oleg Nesterov , "Joel Fernandes, Google" , kernel-team Message-ID: <2113574714.3779.1542031670315.JavaMail.zimbra@efficios.com> In-Reply-To: <20181111194104.GA4787@linux.ibm.com> References: <20181111194104.GA4787@linux.ibm.com> Subject: Re: [PATCH tip/core/rcu 0/41] More RCU flavor consolidation cleanup for v4.21/v5.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.142.138] X-Mailer: Zimbra 8.8.10_GA_3047 (ZimbraWebClient - FF52 (Linux)/8.8.10_GA_3041) Thread-Topic: More RCU flavor consolidation cleanup for v4.21/v5.0 Thread-Index: wSthxDOTXtMSC6VgWohpPZMvbxkGKQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Nov 11, 2018, at 2:41 PM, paulmck paulmck@linux.ibm.com wrote: > Hello! > > This series does additional cleanup for the RCU flavor consolidation, > focusing primarily on uses of old API members, for example, so that > call_rcu_bh() becomes call_rcu(). There are also a few straggling > internal-to-RCU cleanups. > > 1. Remove unused rcu_state externs, courtesy of Joel Fernandes. > > 2. Fix rcu_{node,data} comments about gp_seq_needed, courtesy of > Joel Fernandes. > > 3. Eliminate synchronize_rcu_mult() and its sole caller. > > 4. Consolidate the RCU update functions invoked by sync.c. > > 5-41. Replace old flavorful RCU API calls with the corresponding > vanilla calls. Hi Paul, Just a heads up: we might want to spell out warnings in very big letters for anyone trying to backport code using RCU from post-4.21 kernels back to older kernels. I fear that newer code will build just fine on older kernels, but will spectacularly fail in hard-to-debug ways at runtime. Renaming synchronize_rcu() and call_rcu() to something that did not exist in prior kernels would prevent that. It may not be as pretty though. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com