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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 6F346EAA899 for ; Thu, 12 Jul 2018 18:05:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 248CD208E9 for ; Thu, 12 Jul 2018 18:05:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="q/VUDUBe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 248CD208E9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1726809AbeGLSQF (ORCPT ); Thu, 12 Jul 2018 14:16:05 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:44852 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725967AbeGLSQF (ORCPT ); Thu, 12 Jul 2018 14:16:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=nfspCBSPNkp7AFlPObQwbxQ9nI7MwCFsjprgoBrrrD8=; b=q/VUDUBe7Cz55Qip/EB9UzcGn l/5PvJx6q6BxwtdTvnB2SBFIRO7XNVhWApqdBtA0ebDnNB14UtEQeCvg3+tjaoy6PImoBhOqRXwR+ 4m7lKMCtlg31FEqdVCjFyYbAEZ25ZAEHOZamxTPqLEmlkM4ewILdlm63wBvn23/hS9SfUkHvnR6EG Y1qvle8bdgLPn1/iorOHzmFp8F5Y5lHFTGF7mlBof0MlCUNfF+bT78FiauAogmFfe7YYtbd8tS5EM +Me3xxjqUV10GOT0mteGS7pdV/66MGTQdvOM75nGJ+39w8lHLTapWTeXJg2ba74FgyWWhIDZN7iNt E8x6De89w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fdfxp-0003eV-Ue; Thu, 12 Jul 2018 18:05:14 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C85C220289331; Thu, 12 Jul 2018 20:05:11 +0200 (CEST) Date: Thu, 12 Jul 2018 20:05:11 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Alan Stern , Andrea Parri , Will Deacon , LKMM Maintainers -- Akira Yokosawa , Boqun Feng , Daniel Lustig , David Howells , Jade Alglave , Luc Maranget , Nicholas Piggin , Kernel development list , Linus Torvalds Subject: Re: [PATCH v2] tools/memory-model: Add extra ordering for locks and remove it for ordinary release/acquire Message-ID: <20180712180511.GP2476@hirez.programming.kicks-ass.net> References: <20180712134821.GT2494@hirez.programming.kicks-ass.net> <20180712172838.GU3593@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180712172838.GU3593@linux.vnet.ibm.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 12, 2018 at 10:28:38AM -0700, Paul E. McKenney wrote: > Look for the uses of raw_spin_lock_irq_rcu_node() and friends in > kernel/rcu and include/linux/*rcu*, along with the explanation in > Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html > > I must confess that I am not following exactly what Peter is calling > out as the failure. My best guess is that he is leading up to his > call for RCsc locks, but I might have missed a turn. Yes, it is part of my call for RCsc locks. The locking pattern is fairly simple and shows where RCpc comes apart from expectation real nice. Yes I helped clean up the barrier usage, but as always it'd be even cleaner if we could just do away with the special barrier entirely.