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 9D089EE6447 for ; Fri, 15 Sep 2023 09:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233351AbjIOJQ6 (ORCPT ); Fri, 15 Sep 2023 05:16:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233467AbjIOJQ5 (ORCPT ); Fri, 15 Sep 2023 05:16:57 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E00D210C3; Fri, 15 Sep 2023 02:16:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1694769410; x=1726305410; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=vZq7A/gz70wd7tTFMBwNyA9QmwBFlSJ2HI2SHAFevfQ=; b=Z7z4EblfFpLzuVhAtM4TXs/Cu7Tx6ITDxkzIKPGQhzNxd8t8af8Kzo2e yic+wUwi+ujsR/zgtO6+MIQRD5cAber2/5hPbpyl42C+eRknY+CjOensX znots5p5k9+C9relZ3QhMsIXRg5JQpiVlYCrePLnNa4LXbUb801jNV+35 49RyBLMC13T2FxgdWcQ7popQL5HDP/xaGmLBW1ra6O2l8WyioEvP2CTn8 IRvbE3oVwNIP91viIhxs48aJ1G/TWizztXHtP/guYkSMB/Zdj6JAEofug J6xX8VhyzTbFiafzxrfjwXb6r+PrRRD7BC3HZn2OggPvxHWW0bVQMcq2Z Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10833"; a="443269597" X-IronPort-AV: E=Sophos;i="6.02,148,1688454000"; d="scan'208";a="443269597" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Sep 2023 02:16:50 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10833"; a="810452200" X-IronPort-AV: E=Sophos;i="6.02,148,1688454000"; d="scan'208";a="810452200" Received: from srdoo-mobl1.ger.corp.intel.com ([10.252.38.99]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Sep 2023 02:16:47 -0700 Date: Fri, 15 Sep 2023 12:16:45 +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 , Andy Shevchenko Subject: Re: [PATCH tty v1 08/74] serial: 8250_dw: Use port lock wrappers In-Reply-To: <20230914183831.587273-9-john.ogness@linutronix.de> Message-ID: References: <20230914183831.587273-1-john.ogness@linutronix.de> <20230914183831.587273-9-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-1284566438-1694769409=: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. --8323329-1284566438-1694769409=: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 > --- > drivers/tty/serial/8250/8250_dw.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c > index f4cafca1a7da..95d45dce0880 100644 > --- a/drivers/tty/serial/8250/8250_dw.c > +++ b/drivers/tty/serial/8250/8250_dw.c > @@ -263,20 +263,20 @@ static int dw8250_handle_irq(struct uart_port *p) > * so we limit the workaround only to non-DMA mode. > */ > if (!up->dma && rx_timeout) { > - spin_lock_irqsave(&p->lock, flags); > + uart_port_lock_irqsave(p, &flags); > status = serial_lsr_in(up); > > if (!(status & (UART_LSR_DR | UART_LSR_BI))) > (void) p->serial_in(p, UART_RX); > > - spin_unlock_irqrestore(&p->lock, flags); > + uart_port_unlock_irqrestore(p, flags); > } > > /* Manually stop the Rx DMA transfer when acting as flow controller */ > if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) { > - spin_lock_irqsave(&p->lock, flags); > + uart_port_lock_irqsave(p, &flags); > status = serial_lsr_in(up); > - spin_unlock_irqrestore(&p->lock, flags); > + uart_port_unlock_irqrestore(p, flags); > > if (status & (UART_LSR_DR | UART_LSR_BI)) { > dw8250_writel_ext(p, RZN1_UART_RDMACR, 0); > Reviewed-by: Ilpo Järvinen -- i. --8323329-1284566438-1694769409=:2347--