From patchwork Mon Nov 23 12:22:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 332037 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 415B3C388F9 for ; Mon, 23 Nov 2020 13:34:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E69EB20639 for ; Mon, 23 Nov 2020 13:34:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0dolPQ8H" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730754AbgKWNdl (ORCPT ); Mon, 23 Nov 2020 08:33:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:35344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730040AbgKWMZp (ORCPT ); Mon, 23 Nov 2020 07:25:45 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BA11C208C3; Mon, 23 Nov 2020 12:25:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1606134343; bh=beepN1enpIkIqzm43BzJnt/q7Dpf/K7nNG/A2pLSkbo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0dolPQ8HoJ8FRjKrYrKf8j/MV8ecOpbKtQYTSmcqkGPVle3vybMTETD/iDZv/pv7H vZAoPTB2fk4LeXDQPWOrTk74SPPTf4rH7FsmCkgbq6N+ghtSuiden5EfTykndGFbHR FWMXffydJDCu7UkEDl/aHluXLWw2py+AdPZ76nbA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= , Fugang Duan Subject: [PATCH 4.9 37/47] tty: serial: imx: keep console clocks always on Date: Mon, 23 Nov 2020 13:22:23 +0100 Message-Id: <20201123121807.348822035@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201123121805.530891002@linuxfoundation.org> References: <20201123121805.530891002@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Fugang Duan commit e67c139c488e84e7eae6c333231e791f0e89b3fb upstream. For below code, there has chance to cause deadlock in SMP system: Thread 1: clk_enable_lock(); pr_info("debug message"); clk_enable_unlock(); Thread 2: imx_uart_console_write() clk_enable() clk_enable_lock(); Thread 1: Acuired clk enable_lock -> printk -> console_trylock_spinning Thread 2: console_unlock() -> imx_uart_console_write -> clk_disable -> Acquite clk enable_lock So the patch is to keep console port clocks always on like other console drivers. Fixes: 1cf93e0d5488 ("serial: imx: remove the uart_console() check") Acked-by: Uwe Kleine-König Signed-off-by: Fugang Duan Link: https://lore.kernel.org/r/20201111025136.29818-1-fugang.duan@nxp.com Cc: stable [fix up build warning - gregkh] Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 20 +++----------------- 1 file changed, 3 insertions(+), 17 deletions(-) --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1787,16 +1787,6 @@ imx_console_write(struct console *co, co unsigned int ucr1; unsigned long flags = 0; int locked = 1; - int retval; - - retval = clk_enable(sport->clk_per); - if (retval) - return; - retval = clk_enable(sport->clk_ipg); - if (retval) { - clk_disable(sport->clk_per); - return; - } if (sport->port.sysrq) locked = 0; @@ -1832,9 +1822,6 @@ imx_console_write(struct console *co, co if (locked) spin_unlock_irqrestore(&sport->port.lock, flags); - - clk_disable(sport->clk_ipg); - clk_disable(sport->clk_per); } /* @@ -1935,15 +1922,14 @@ imx_console_setup(struct console *co, ch retval = uart_set_options(&sport->port, co, baud, parity, bits, flow); - clk_disable(sport->clk_ipg); if (retval) { - clk_unprepare(sport->clk_ipg); + clk_disable_unprepare(sport->clk_ipg); goto error_console; } - retval = clk_prepare(sport->clk_per); + retval = clk_prepare_enable(sport->clk_per); if (retval) - clk_unprepare(sport->clk_ipg); + clk_disable_unprepare(sport->clk_ipg); error_console: return retval;