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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 B7F20ECDFB1 for ; Fri, 13 Jul 2018 09:28:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C2482087C for ; Fri, 13 Jul 2018 09:28:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7C2482087C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.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 S1728187AbeGMJmV (ORCPT ); Fri, 13 Jul 2018 05:42:21 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59600 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726789AbeGMJmV (ORCPT ); Fri, 13 Jul 2018 05:42:21 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 6CE4DBB3; Fri, 13 Jul 2018 09:28:31 +0000 (UTC) Date: Fri, 13 Jul 2018 11:28:28 +0200 From: Greg Kroah-Hartman To: Tycho Andersen Cc: Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, "Serge E . Hallyn" Subject: Re: [PATCH v4] uart: fix race between uart_put_char() and uart_shutdown() Message-ID: <20180713092828.GA6589@kroah.com> References: <20180706212220.GC3583@cisco.lan> <20180711160744.32074-1-tycho@tycho.ws> <20180712150438.GF22502@kroah.com> <20180712150822.GC13192@cisco.cisco.com> <20180712154015.GC13114@kroah.com> <20180712181846.GD13192@cisco.cisco.com> <20180712182545.GA30099@kroah.com> <20180712183001.GE13192@cisco.cisco.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180712183001.GE13192@cisco.cisco.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 12:30:01PM -0600, Tycho Andersen wrote: > On Thu, Jul 12, 2018 at 08:25:45PM +0200, Greg Kroah-Hartman wrote: > > On Thu, Jul 12, 2018 at 12:18:46PM -0600, Tycho Andersen wrote: > > > On Thu, Jul 12, 2018 at 05:40:15PM +0200, Greg Kroah-Hartman wrote: > > > > On Thu, Jul 12, 2018 at 09:08:22AM -0600, Tycho Andersen wrote: > > > > > On Thu, Jul 12, 2018 at 05:04:38PM +0200, Greg Kroah-Hartman wrote: > > > > > > On Wed, Jul 11, 2018 at 10:07:44AM -0600, Tycho Andersen wrote: > > > > > > > + if (uport) > > > > > > > + spin_lock_irqsave(&uport->lock, flags); > > > > > > > > > > > > That's the same thing as just calling uart_port_lock(), why aren't you > > > > > > doing that? > > > > > > > > > > Because the compiler can't seem to "see" through the macros/ref calls, > > > > > and I get the warning I mentioned here if I use them: > > > > > > > > > > https://lkml.org/lkml/2018/7/6/840 > > > > > > > > What horrible version of gcc are you using that give you that? Don't > > > > open-code things just because of a broken compiler. > > > > > > I've tried with both 7.3.0 and 5.4.0. I think the reason we see this > > > here but not elsewhere in the file is because there's an actual > > > function call (free_page()) in the critical section. > > > > > > If we move that out, something like the below patch, it all works for > > > me. > > > > Ick. Which version of this series had the problem? Let me test it out > > here... > > v3, if you remove the initialization of flags from both functions you > should see it. Ok, I tried v3 out and yes, you are right, removing the "= 0" causes gcc to complain. The compiler is being dumb here, so I'll just leave it as-is. I've queued up the v3 version now, thanks for sticking with this. greg k-h