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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 9B827C2D0DB for ; Wed, 29 Jan 2020 18:49:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7416E20708 for ; Wed, 29 Jan 2020 18:49:46 +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="sr/jic7X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727244AbgA2Stp (ORCPT ); Wed, 29 Jan 2020 13:49:45 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:34396 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726203AbgA2Stp (ORCPT ); Wed, 29 Jan 2020 13:49:45 -0500 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=KUyQBoXhEovxNfF4eKqrkEbw0GAhd/ZaP73j2VawXbg=; b=sr/jic7XwIUCAb9Yov3R6yWJE fht2fWtsFqeDcJKhtdq/x0dZFk2IYPs7jmVXtwDLbH4Vxq4h/BdnO2mMywRD//nscDUXtfkLLex0u rFAN465ynySb1AMEJO6v7LGFzg0klNKhIw4RzCTUMZh1D+LPcPL8bWW4X8LyiDoW04dhqx6tcY09Z 8JcKEl5IRM4+ZDSUviHof0rjAe7yz2cfWkh66J6k4MhEhQ9tz119EAlqkr798g5iaBN6wXZTjFNZL Y6BCwObZx9vnanOuGcIshOpHej8PnQvimGAQXdqEaZPDAWh5i/S7BpumCTqyp3anwvw3BPdNCk713 nfCEs0qLQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iwsPB-00028n-UZ; Wed, 29 Jan 2020 18:49:40 +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 178F33035D4; Wed, 29 Jan 2020 19:47:53 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id F082D2B7A8620; Wed, 29 Jan 2020 19:49:35 +0100 (CET) Date: Wed, 29 Jan 2020 19:49:35 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Marco Elver , Qian Cai , Will Deacon , Ingo Molnar , Linux Kernel Mailing List , kasan-dev Subject: Re: [PATCH] locking/osq_lock: fix a data race in osq_wait_next Message-ID: <20200129184935.GU14879@hirez.programming.kicks-ass.net> References: <20200122165938.GA16974@willie-the-truck> <20200122223851.GA45602@google.com> <20200123093905.GU14914@hirez.programming.kicks-ass.net> <20200128165655.GM14914@hirez.programming.kicks-ass.net> <20200129002253.GT2935@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200129002253.GT2935@paulmck-ThinkPad-P72> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 28, 2020 at 04:22:53PM -0800, Paul E. McKenney wrote: > On Tue, Jan 28, 2020 at 05:56:55PM +0100, Peter Zijlstra wrote: > > On Tue, Jan 28, 2020 at 12:46:26PM +0100, Marco Elver wrote: > > > > > > Marco, any thought on improving KCSAN for this to reduce the false > > > > positives? > > > > > > Define 'false positive'. > > > > I'll use it where the code as written is correct while the tool > > complains about it. > > I could be wrong, but I would guess that Marco is looking for something > a little less subjective and a little more specific. ;-) How is that either? If any valid translation by a compile results in correct functionality, yet the tool complains, then surely we can speak of a objective fact.