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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 E198AC41514 for ; Mon, 29 Jul 2019 19:41:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3F53205F4 for ; Mon, 29 Jul 2019 19:41:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429292; bh=ZBJ79+KNPR3qfgggcd1jIRFTHX+Nclci3drFihOHSog=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=BdPMcaVK4fxKcY9XB2JJXEtp9u894u0d+dIf3GVUjzqdVAdzWNgavDFN0kFZDz6F1 BiJVwxZPxtyMImvsM1heGOSpEv4AMOMgTeNVgfz35+3iNWVZ4Kv9fDUayhEbCCJVuc cXfidqwm6tG91KAN5U0AmhgUYhYS0XHAMK4vBApI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389366AbfG2Tlb (ORCPT ); Mon, 29 Jul 2019 15:41:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:56944 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389329AbfG2Tl2 (ORCPT ); Mon, 29 Jul 2019 15:41:28 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 9AF2D205F4; Mon, 29 Jul 2019 19:41:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564429287; bh=ZBJ79+KNPR3qfgggcd1jIRFTHX+Nclci3drFihOHSog=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jy+LOLsMpmLsZYF3BT9MsaJJ4wafl33Sm+hjsLEzJtbEOiX22Ac0Dm0AjCSvL0ccP bWq13itetPDqfp9Auo6SIo3dtD+laxkSSf1+2AHFj1ipcpdu/KUSyiXjNwBbblgh6v hi6ppYgHRNZ5Ec0I7UoSr8zC/yIkho646L6KtmK4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Serge Semin , Sasha Levin Subject: [PATCH 4.19 033/113] tty: serial_core: Set port active bit in uart_port_activate Date: Mon, 29 Jul 2019 21:22:00 +0200 Message-Id: <20190729190703.738844723@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190729190655.455345569@linuxfoundation.org> References: <20190729190655.455345569@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit 13b18d35909707571af9539f7731389fbf0feb31 ] A bug was introduced by commit b3b576461864 ("tty: serial_core: convert uart_open to use tty_port_open"). It caused a constant warning printed into the system log regarding the tty and port counter mismatch: [ 21.644197] ttyS ttySx: tty_port_close_start: tty->count = 1 port count = 2 in case if session hangup was detected so the warning is printed starting from the second open-close iteration. Particularly the problem was discovered in situation when there is a serial tty device without hardware back-end being setup. It is considered by the tty-serial subsystems as a hardware problem with session hang up. In this case uart_startup() will return a positive value with TTY_IO_ERROR flag set in corresponding tty_struct instance. The same value will get passed to be returned from the activate() callback and then being returned from tty_port_open(). But since in this case tty_port_block_til_ready() isn't called the TTY_PORT_ACTIVE flag isn't set (while the method had been called before tty_port_open conversion was introduced and the rest of the subsystem code expected the bit being set in this case), which prevents the uart_hangup() method to perform any cleanups including the tty port counter setting to zero. So the next attempt to open/close the tty device will discover the counters mismatch. In order to fix the problem we need to manually set the TTY_PORT_ACTIVE flag in case if uart_startup() returned a positive value. In this case the hang up procedure will perform a full set of cleanup actions including the port ref-counter resetting. Fixes: b3b576461864 "tty: serial_core: convert uart_open to use tty_port_open" Signed-off-by: Serge Semin Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/serial_core.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 8dbeb14a1e3a..fe9261ffe3db 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1738,6 +1738,7 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty) { struct uart_state *state = container_of(port, struct uart_state, port); struct uart_port *uport; + int ret; uport = uart_port_check(state); if (!uport || uport->flags & UPF_DEAD) @@ -1748,7 +1749,11 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty) /* * Start up the serial port. */ - return uart_startup(tty, state, 0); + ret = uart_startup(tty, state, 0); + if (ret > 0) + tty_port_set_active(port, 1); + + return ret; } static const char *uart_type(struct uart_port *port) -- 2.20.1