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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_MED, 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 C762AECDFB1 for ; Fri, 13 Jul 2018 14:01:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 811FF208A4 for ; Fri, 13 Jul 2018 14:01:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=tycho-ws.20150623.gappssmtp.com header.i=@tycho-ws.20150623.gappssmtp.com header.b="JR78PE3Z" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 811FF208A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=tycho.ws 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 S1730339AbeGMOQb (ORCPT ); Fri, 13 Jul 2018 10:16:31 -0400 Received: from mail-io0-f196.google.com ([209.85.223.196]:35503 "EHLO mail-io0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729739AbeGMOQb (ORCPT ); Fri, 13 Jul 2018 10:16:31 -0400 Received: by mail-io0-f196.google.com with SMTP id q4-v6so31414435iob.2 for ; Fri, 13 Jul 2018 07:01:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tycho-ws.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=pko1GoJ1pOfD30f/OdemZYk91HK9FJtw+53DRjEwbB4=; b=JR78PE3ZNOpwsECWWZIY9D4vFDLJdSL1E47mJT38ZbGAC/6STPgRA+MEDISv6FuvxL tWHCA5uL1ppOIYD7Weks1CpjNKRY1Lo9KnOaLUeHvxQiJKK1Dyrawn3KPMXXnYEiYgtj +lWGxK1Vc1UxsWPy9+balxcm/pJwvxATNxWsInlPN9flri/0cY6f+A4VLqpoOUS6eyUZ qKUFynl5WYpHobFsPWigYeR/U+/H3VVKlKXjPlm7nxdX5wP6lIjZagIMUSnLG7yDTRTV 5iudr4gNW+nR2hzaCsdGL7ybKgaFtSjwY3yGMxDRsD7H8CnPJLh+uN23yJ9IZilOty1B rrQA== 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=pko1GoJ1pOfD30f/OdemZYk91HK9FJtw+53DRjEwbB4=; b=RD2GIVj/CroDuf/niV+CrQ7qrfvusleAYl3KdEhbFkEPtbdjqR7Alx3uZqcSlVqUJd 9ZDNiiwomsEOk+YveDlidGAYbtmDw2I64Oq4SRLGtm9LidRuPHBmDHHn6wlADSHIqCjs KUNWzpt2ojz6QWyVMKq7n/OOIg0wcy63pzXD4InVe/dxXHN7sNRTyviToyL0IHniYU9j fhaZ8im/CggC+86AzFK1nfmKSy61FZn31bHl3vD5wX6tlhKuv3A8JA0nf2+vTIwNR0mA cV1JlVB+VrO5m0NlXlSbQqwgn+cnPtHX4Ca+EbMvYvQEuL4xg+9czw2dmpkw6fP+yfRC D7Kg== X-Gm-Message-State: APt69E2TKdp6y3gDlZ2DazgeqsbiM1havZVzW7R/Gn2Uew5R7e0sa4u8 sUH0PL1vHOnIJn0kiQqnBLEmy7bF X-Google-Smtp-Source: AAOMgpcK+RyWShvonZcKF/GSgMIvVQ9d24RFIvW+8kifGojaloZ3LIHS6VO2Xlg7eGOF4kktELf6cA== X-Received: by 2002:a6b:97c6:: with SMTP id z189-v6mr29537268iod.41.1531490504120; Fri, 13 Jul 2018 07:01:44 -0700 (PDT) Received: from cisco.cisco.com ([8.24.24.129]) by smtp.gmail.com with ESMTPSA id u15-v6sm10784200iog.62.2018.07.13.07.01.42 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 13 Jul 2018 07:01:43 -0700 (PDT) Date: Fri, 13 Jul 2018 08:01:42 -0600 From: Tycho Andersen To: Greg Kroah-Hartman 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: <20180713140142.GH13192@cisco.cisco.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> <20180713092828.GA6589@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180713092828.GA6589@kroah.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 13, 2018 at 11:28:28AM +0200, Greg Kroah-Hartman wrote: > 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. Great, thanks! Tycho