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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 448AAC33CB3 for ; Tue, 28 Jan 2020 09:37:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10EC820CC7 for ; Tue, 28 Jan 2020 09:37:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="PGA10LSX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725974AbgA1Jha (ORCPT ); Tue, 28 Jan 2020 04:37:30 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:40358 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725271AbgA1Jh3 (ORCPT ); Tue, 28 Jan 2020 04:37:29 -0500 Received: by mail-pg1-f195.google.com with SMTP id k25so6675617pgt.7 for ; Tue, 28 Jan 2020 01:37:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=+cWPpo+JboGnintSd8zwFs8NMb29/E+sQ20smaqzcvA=; b=PGA10LSXyDmz2JOek4Re1Jt1c27N7Xn1opWiQHVC+oCL+YGlHWlQEmQGK9xOopi0a/ RCBDMO5u06EPDogTd8NLWuH412lPsX4/I6z3TFYlUAfw5oYKOGn5AOw1NlGtjmReXoNs 3lcrX5ANvY4IJVx5SMky+y2lOn0kLfANp7fzNzf0kCDp+/dTMG+2BEXRJ9+W69QykHNr hFRJpqy0ab/zBoDcKHR/lP4mXAiW2icCUVgM3050nyehzSfBXa1mce3J9igGmWAYakzs RjHsMOgxJszzArYpyxQfiGDnfH0thk8yc/RnjYXiTPthN21GlSXbqfpC//gg3qn4z4Af TWWQ== 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=+cWPpo+JboGnintSd8zwFs8NMb29/E+sQ20smaqzcvA=; b=QzCCCQzaE+6YvT/+ijxCmt6McRErGqo+guImShAP0hKTPecEVfel+6iQXNHL24bGqS 5mgYjcHfNOojghRL+GsYaMlKGCWzsKnwfEBiJrd4Nbh9DHuIAy7P5tX0cy1mRtbwLcX9 tXCxsqOdpbw1FujKoOKXmE5tOLwk2Y9jeajEWaA4t4yyHh3Hd4XwICg8UpeCowLUv2rK v+FH0xsbY56eDVsIQqYOj20AetkBtoBhVGoLLjtaVc1nJKMkxJ9Q4HjXqY0/TJzjeUnV VbP0dam5CMmaquMlIWPmYeUf+enLRrdeQKlhNCzwB11Idw+RqBnKlu8J3GH+vGQ3hblB 3e/A== X-Gm-Message-State: APjAAAVYz3JJRIr/qw6fe0IXVo66IOWYvu3Qz8Dno63NLcklL84rol2r oyEJs9LhM7ESmQfnzPDx6C4vRPC6 X-Google-Smtp-Source: APXvYqz7EI8uZApqRo9ucWVFVd9sQLcWFN3yQwep9F1+ZWwCJo0/RcYc+wUzrBeMRNpVRU09nKjjFw== X-Received: by 2002:a63:447:: with SMTP id 68mr25029230pge.364.1580204249251; Tue, 28 Jan 2020 01:37:29 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:5bbb:c872:f2b1:f53b]) by smtp.gmail.com with ESMTPSA id d22sm18955568pgg.52.2020.01.28.01.37.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jan 2020 01:37:28 -0800 (PST) Date: Tue, 28 Jan 2020 18:37:26 +0900 From: Sergey Senozhatsky To: Andy Shevchenko Cc: Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 4/5] console: Avoid positive return code from unregister_console() Message-ID: <20200128093726.GE115889@google.com> References: <20200127114719.69114-1-andriy.shevchenko@linux.intel.com> <20200127114719.69114-4-andriy.shevchenko@linux.intel.com> <20200128044332.GA115889@google.com> <20200128092235.GX32742@smile.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200128092235.GX32742@smile.fi.intel.com> 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 (20/01/28 11:22), Andy Shevchenko wrote: > On Tue, Jan 28, 2020 at 01:43:32PM +0900, Sergey Senozhatsky wrote: > > On (20/01/27 13:47), Andy Shevchenko wrote: > > [..] > > > res = _braille_unregister_console(console); > > > - if (res) > > > + if (res < 0) > > > return res; > > > + if (res > 0) > > > + return 0; > > > > > > - res = 1; > > > + res = -ENODEV; > > > console_lock(); > > > if (console_drivers == console) { > > > console_drivers=console->next; > > > @@ -2838,6 +2840,9 @@ int unregister_console(struct console *console) > > > if (!res && (console->flags & CON_EXTENDED)) > > > nr_ext_console_drivers--; > > > > > > + if (res && !(console->flags & CON_ENABLED)) > > > + res = 0; > > > > Console is not on the console_drivers list. Why does !ENABLED case > > require extra handling? > > It's mirroring (to some extend) the register_console() abort conditions. Could you please explain? I see the "newcon->flags & CON_ENABLED" error out path. I'm guessing, that the expectation is that this is how we filter out consoles which were not matched (there is that "newcon->flags |= CON_ENABLED" several lines earlier.) So this looks like the assumption is that consoles don't have CON_ENABLED bit set prior to register_console(), as far as I understand. Well, look at these ... drivers/net/netconsole.c: .flags = CON_ENABLED, drivers/tty/ehv_bytechan.c: .flags = CON_PRINTBUFFER | CON_ENABLED, drivers/tty/serial/mux.c: .flags = CON_ENABLED | CON_PRINTBUFFER, ... -ss