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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 77A4DC43331 for ; Tue, 24 Mar 2020 16:51:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F94D206F6 for ; Tue, 24 Mar 2020 16:51:42 +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="SWI87RLR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727600AbgCXQvl (ORCPT ); Tue, 24 Mar 2020 12:51:41 -0400 Received: from merlin.infradead.org ([205.233.59.134]:42084 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725767AbgCXQvl (ORCPT ); Tue, 24 Mar 2020 12:51:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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; bh=N4GZ7+M1eRD8an5K8OELlYenKfDSxyisShOnVR18rRU=; b=SWI87RLREq1G8eS1Z3UkgbOL0p bNHNo+3m3jDy6NqaD6lgk6E9M55IYXv9cfhQ4U/m3TXNeU0F2KlTX53PnObUuMNeVlJ1gkH2u2N6R D5gvmeidJjwsqgsFdXisT18Q7t5TQ6VhFQ+3m90HRTger2cxdygkelqCgubtTt9c2XQU43UDatsqN hT8WBbB2aFRGRhmAq8BnWOkIGcld4281RMuTyMKV6/G+s23GqR12lnGg03FVfw+8bRTXRnLGqVMJw 75U0QGdWL580574YY2M7/tE8Nr4hP6vt2L8s/nVucP+OSxxOC3HSp8eXiqjwLmRlNWv8r6tfkBn+f oXqZY5kw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jGmm3-0007dt-99; Tue, 24 Mar 2020 16:51:31 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3FDB6306118; Tue, 24 Mar 2020 17:51:28 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2057920200A0F; Tue, 24 Mar 2020 17:51:28 +0100 (CET) Date: Tue, 24 Mar 2020 17:51:28 +0100 From: Peter Zijlstra To: Will Deacon Cc: linux-kernel@vger.kernel.org, Eric Dumazet , Jann Horn , Kees Cook , Maddie Stone , Marco Elver , "Paul E . McKenney" , Thomas Gleixner , kernel-team@android.com, kernel-hardening@lists.openwall.com, Oleg Nesterov Subject: Re: [RFC PATCH 03/21] list: Annotate lockless list primitives with data_race() Message-ID: <20200324165128.GS20696@hirez.programming.kicks-ass.net> References: <20200324153643.15527-1-will@kernel.org> <20200324153643.15527-4-will@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200324153643.15527-4-will@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 24, 2020 at 03:36:25PM +0000, Will Deacon wrote: > diff --git a/include/linux/list.h b/include/linux/list.h > index 4fed5a0f9b77..4d9f5f9ed1a8 100644 > --- a/include/linux/list.h > +++ b/include/linux/list.h > @@ -279,7 +279,7 @@ static inline int list_is_last(const struct list_head *list, > */ > static inline int list_empty(const struct list_head *head) > { > - return READ_ONCE(head->next) == head; > + return data_race(READ_ONCE(head->next) == head); > } list_empty() isn't lockless safe, that's what we have list_empty_careful() for.