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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 11649C76195 for ; Fri, 19 Jul 2019 08:50:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC2BA2080D for ; Fri, 19 Jul 2019 08:50:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="ECe6NvFo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727177AbfGSIuF (ORCPT ); Fri, 19 Jul 2019 04:50:05 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:52717 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725798AbfGSIuF (ORCPT ); Fri, 19 Jul 2019 04:50:05 -0400 Received: by mail-wm1-f67.google.com with SMTP id s3so27999029wms.2 for ; Fri, 19 Jul 2019 01:50:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=x2r2aQ0QfHY0nbhB8cKUFwTSscENmMp03cfv/kAtz7Y=; b=ECe6NvFo9wxPW1KC/Bjj1V5Zw+hvSQIZC14D0c9t7qsZTaNWqBorE0RRdRjd9934XP 0WQBGEVDEE/bb+iIeZ2ue4n0IfJnstlHhCNdo1wVK/mX3ewodcNOk+d5AWKtmPKyzoZY wDlVBnqCglJtKov9IN6I+jKadOGEV8OFsVvpI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=x2r2aQ0QfHY0nbhB8cKUFwTSscENmMp03cfv/kAtz7Y=; b=kSl65j4jNQe6GHz9yyE0Re8L3/Er3G9BQWo9kDfimC0MSjk0T8cxJk+v9RXE9BpSlW AdUvDTh9DujAifHWO5VgpdOti7H4KkstjXS8rcwqyTcKF6YGAPTC2ySy0h+Zr368zRgu a8sOab+4NOhEO9YF+em/gBb7Hu0196i1o4q82SzVibZ5ik23bVnQ8xppRLYd6B4+DL/H R8uN3kDhRsi4doiLMzd0edeWlEBiOZF5DsBxoqrViMzhb5XWo2LyYNWRJcwYDXR5NNEY G4me4WDI3I4D72ZUms9bnvWsafFSakRmechO+V9zDwN6x0E1j3m7ifQtwIQTVDRytflF cvJA== X-Gm-Message-State: APjAAAXCvx9/i62mAkVNNJ2dSsCA15xAX3+pckL3FOFTFYHit76wql1u gGa7PwjMVXwyaAXA1Pz4cncCaH2lxTqaVg== X-Google-Smtp-Source: APXvYqw1JoWpLmH3YD/r76UHhkPwn+eK0Lt86eaNgA2NYQx2iNZXlwVsI/0LQEeSDJqlXMXeLFi1Mg== X-Received: by 2002:a7b:cc81:: with SMTP id p1mr44941846wma.107.1563526203377; Fri, 19 Jul 2019 01:50:03 -0700 (PDT) Received: from andrea (host234-214-static.12-87-b.business.telecomitalia.it. [87.12.214.234]) by smtp.gmail.com with ESMTPSA id e3sm26110515wrs.37.2019.07.19.01.50.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jul 2019 01:50:02 -0700 (PDT) Date: Fri, 19 Jul 2019 10:49:56 +0200 From: Andrea Parri To: Peter Zijlstra Cc: Will Deacon , linux-kernel@vger.kernel.org, Jan Stancek , Waiman Long , dbueso@suse.de, mingo@redhat.com, jade.alglave@arm.com, paulmck@linux.vnet.ibm.com Subject: Re: [PATCH 1/4] locking/rwsem: Add missing ACQUIRE to read_slowpath exit when queue is empty Message-ID: <20190719084956.GA6750@andrea> References: <20190718134954.496297975@infradead.org> <20190718135205.916241783@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190718135205.916241783@infradead.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > @@ -1032,6 +1032,8 @@ rwsem_down_read_slowpath(struct rw_semap > */ > if (adjustment && !(atomic_long_read(&sem->count) & > (RWSEM_WRITER_MASK | RWSEM_FLAG_HANDOFF))) { > + /* Provide lock ACQUIRE */ > + smp_acquire__after_ctrl_dep(); Does this also make the lock RCtso? Or maybe RCtso was already guaranteed (and I'm failing to see why)? Thanks, Andrea