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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC2FEEE644B for ; Fri, 15 Sep 2023 09:26:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233633AbjIOJ0e (ORCPT ); Fri, 15 Sep 2023 05:26:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233680AbjIOJ0e (ORCPT ); Fri, 15 Sep 2023 05:26:34 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB80730DF; Fri, 15 Sep 2023 02:25:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694769910; x=1726305910; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=Dl5e9nvtvoay6nbLKFpX4/b6GOacVIKhsuZx+SNWBWA=; b=N7sWQtSCkRjss5ezN0UDBcSZh26zmb1rpPHA9sM1fLAeqjQxh7xxwCBr F/XdTUv8xhMksLRphCPx7YBwGMYLsjyVsI4ph2+zVTqrgH+RCPIn5c6CJ CTeRlbWaJPYflXd+Qd32Y3eZXAWqMJnurRsxmfpmJ9bDPuwf9cmJ9IMB7 SSDsTwflK0XjvgiEIuRhJbGa8ts10Oi6isZWu5gNypj4vRmsX/OsI3dm3 J59oXd4LMO7alA+/yZB/TmjYI6qCbgjERPSK6EfXfpwudM7dgqaTL34ZE zPyqHndZSO/P6bnGee0P/hEwKk+KvTsFvO0ihXJvl1E7YE5o5/nzThWd2 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10833"; a="465571244" X-IronPort-AV: E=Sophos;i="6.02,148,1688454000"; d="scan'208";a="465571244" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Sep 2023 02:24:58 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10833"; a="738264445" X-IronPort-AV: E=Sophos;i="6.02,148,1688454000"; d="scan'208";a="738264445" Received: from srdoo-mobl1.ger.corp.intel.com ([10.252.38.99]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Sep 2023 02:24:55 -0700 Date: Fri, 15 Sep 2023 12:24:52 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: John Ogness cc: Greg Kroah-Hartman , Jiri Slaby , linux-serial , Petr Mladek , Thomas Gleixner , LKML , Tony Lindgren , Andy Shevchenko , Florian Fainelli Subject: Re: [PATCH tty v1 06/74] serial: 8250: Use port lock wrappers In-Reply-To: <20230914183831.587273-7-john.ogness@linutronix.de> Message-ID: <4f44c64d-bd2-c10-8ae3-25f1b4594df@linux.intel.com> References: <20230914183831.587273-1-john.ogness@linutronix.de> <20230914183831.587273-7-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-1271593363-1694769897=:2347" Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1271593363-1694769897=:2347 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 8BIT On Thu, 14 Sep 2023, John Ogness wrote: > From: Thomas Gleixner > > When a serial port is used for kernel console output, then all > modifications to the UART registers which are done from other contexts, > e.g. getty, termios, are interference points for the kernel console. > > So far this has been ignored and the printk output is based on the > principle of hope. The rework of the console infrastructure which aims to > support threaded and atomic consoles, requires to mark sections which > modify the UART registers as unsafe. This allows the atomic write function > to make informed decisions and eventually to restore operational state. It > also allows to prevent the regular UART code from modifying UART registers > while printk output is in progress. > > All modifications of UART registers are guarded by the UART port lock, > which provides an obvious synchronization point with the console > infrastructure. > > To avoid adding this functionality to all UART drivers, wrap the > spin_[un]lock*() invocations for uart_port::lock into helper functions > which just contain the spin_[un]lock*() invocations for now. In a > subsequent step these helpers will gain the console synchronization > mechanisms. > > Converted with coccinelle. No functional change. > > Signed-off-by: Thomas Gleixner Reviewed-by: Ilpo Järvinen -- i. --8323329-1271593363-1694769897=:2347--