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=-5.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 0127DC43331 for ; Tue, 31 Mar 2020 13:12:18 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 50F70206F5 for ; Tue, 31 Mar 2020 13:12:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="WDyMaOIu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50F70206F5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18335-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 18332 invoked by uid 550); 31 Mar 2020 13:12:11 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 18298 invoked from network); 31 Mar 2020 13:12:10 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585660319; bh=C4z6bLsgCUsUXpNs+07nkuMCLbbtGzUm2/UZT5f2VDA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WDyMaOIuFYL2OPYRlanpB+zCrBj+VAdJdLyumi/WLOjuNjpmicwMmy761XmmzOuUf w4tbemfSc178iooJo7SYmeCJalI49A0bXwz9TscqfPkHfEjkkga+X8QtcIMfvR2iCm zQCjNN2n3yGIWKd8NdX9ZXfk+TOiL/vDYVSyf0O8= Date: Tue, 31 Mar 2020 14:11:54 +0100 From: Will Deacon To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, Eric Dumazet , Jann Horn , Kees Cook , Maddie Stone , Marco Elver , Peter Zijlstra , Thomas Gleixner , kernel-team@android.com, kernel-hardening@lists.openwall.com Subject: Re: [RFC PATCH 08/21] Revert "list: Use WRITE_ONCE() when initializing list_head structures" Message-ID: <20200331131153.GB30975@willie-the-truck> References: <20200324153643.15527-1-will@kernel.org> <20200324153643.15527-9-will@kernel.org> <20200330232505.GD19865@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200330232505.GD19865@paulmck-ThinkPad-P72> User-Agent: Mutt/1.10.1 (2018-07-13) On Mon, Mar 30, 2020 at 04:25:05PM -0700, Paul E. McKenney wrote: > On Tue, Mar 24, 2020 at 03:36:30PM +0000, Will Deacon wrote: > > This reverts commit 2f073848c3cc8aff2655ab7c46d8c0de90cf4e50. > > > > There is no need to use WRITE_ONCE() to initialise a non-RCU 'list_head'. > > > > Cc: Paul E. McKenney > > Cc: Peter Zijlstra > > Signed-off-by: Will Deacon > > And attention to lockless uses of list_empty() here, correct? > > Depending on the outcome of discussions on 3/21, I should have added in > all three cases. Yes, patch 3 is where this will get sorted. It looks like we'll have to disable KCSAN around the READ_ONCE() over there, but I also need to finish wrapping my head around list_empty_careful() because I'm deeply suspicious! Will