Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756671AbaDWKdn (ORCPT ); Wed, 23 Apr 2014 06:33:43 -0400 Received: from mail.pcs.de ([145.253.69.50]:7738 "EHLO exchange5.pcs.ditec.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756171AbaDWKdk (ORCPT ); Wed, 23 Apr 2014 06:33:40 -0400 Date: Wed, 23 Apr 2014 12:33:22 +0200 From: Thomas Pfaff X-X-Sender: tpfaff@lxtpfaff.pcs.ditec.de To: , , CC: Subject: [PATCH v2] serial_core: fix uart PORT_UNKNOWN handling Message-ID: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-GFI-SMTP-Submission: 1 X-GFI-SMTP-Submission: 1 X-GFI-SMTP-HelloDomain: lxtpfaff.pcs.ditec.de X-GFI-SMTP-RemoteIP: 192.168.9.96 X-KSE-AntiSpam-Interceptor-Info: white sender email list X-GFIME-MASPAM: SPAM X-KSE-Antivirus-Interceptor-Info: scan successful X-KSE-Antivirus-Info: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Thomas Pfaff" While porting a RS485 driver from 2.6.29 to 3.14, i noticed that the serial tty driver could break it by using uart ports that it does not own : 1. uart_change_pm ist called during uart_open and calls the uart pm function without checking for PORT_UNKNOWN. The fix is to move uart_change_pm from uart_open to uart_port_startup. 2. The return code from the uart request_port call in uart_set_info is not handled properly, leading to the situation that the serial driver also thinks it owns the uart ports. This can triggered by doing following actions : setserial /dev/ttyS0 uart none # release the uart ports modprobe lirc-serial # or any other device that uses the uart setserial /dev/ttyS0 uart 16550 # gives no error and the uart tty driver # can use the ports as well Signed-off-by: Thomas Pfaff --- diff -urp linux-3.14.org/drivers/tty/serial/serial_core.c linux-3.14/drivers/tty/serial/serial_core.c --- linux-3.14.org/drivers/tty/serial/serial_core.c 2014-03-31 05:40:15.000000000 +0200 +++ linux-3.14/drivers/tty/serial/serial_core.c 2014-04-09 16:41:03.940046814 +0200 @@ -138,6 +138,11 @@ static int uart_port_startup(struct tty_ return 1; /* + * Make sure the device is in D0 state. + */ + uart_change_pm(state, UART_PM_STATE_ON); + + /* * Initialise and allocate the transmit and temporary * buffer. */ @@ -826,25 +831,29 @@ static int uart_set_info(struct tty_stru * If we fail to request resources for the * new port, try to restore the old settings. */ - if (retval && old_type != PORT_UNKNOWN) { + if (retval) { uport->iobase = old_iobase; uport->type = old_type; uport->hub6 = old_hub6; uport->iotype = old_iotype; uport->regshift = old_shift; uport->mapbase = old_mapbase; - retval = uport->ops->request_port(uport); - /* - * If we failed to restore the old settings, - * we fail like this. - */ - if (retval) - uport->type = PORT_UNKNOWN; - /* - * We failed anyway. - */ - retval = -EBUSY; + if (old_type != PORT_UNKNOWN) { + retval = uport->ops->request_port(uport); + /* + * If we failed to restore the old settings, + * we fail like this. + */ + if (retval) + uport->type = PORT_UNKNOWN; + + /* + * We failed anyway. + */ + retval = -EBUSY; + } + /* Added to return the correct error -Ram Gupta */ goto exit; } @@ -1570,12 +1579,6 @@ static int uart_open(struct tty_struct * } /* - * Make sure the device is in D0 state. - */ - if (port->count == 1) - uart_change_pm(state, UART_PM_STATE_ON); - - /* * Start up the serial port. */ retval = uart_startup(tty, state, 0); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/