From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932334AbWGDTls (ORCPT ); Tue, 4 Jul 2006 15:41:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932338AbWGDTls (ORCPT ); Tue, 4 Jul 2006 15:41:48 -0400 Received: from perninha.conectiva.com.br ([200.140.247.100]:21137 "EHLO perninha.conectiva.com.br") by vger.kernel.org with ESMTP id S932334AbWGDTls (ORCPT ); Tue, 4 Jul 2006 15:41:48 -0400 Date: Tue, 4 Jul 2006 16:41:38 -0300 From: "Luiz Fernando N. Capitulino" To: akpm@osdl.org Cc: LKML , Paul Fulghum , Greg KH , Russell King , Pete Zaitcev , linux-usb-devel@lists.sourceforge.net Subject: [PATCH] Serial-Core: adds atomic context debug code. Message-ID: <20060704164138.0bfd6e27@doriath.conectiva> Organization: Mandriva X-Mailer: Sylpheed-Claws 2.4.0-rc2 (GTK+ 2.9.4; i586-mandriva-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew, While porting the USB-Serial layer to the Serial Core API [1], we found that usb-serial devices must be able to sleep in the get_mctrl() and set_mctrl() callbacks [2]. But, unfortunately, those callbacks are called with a spinlock held. The solution is to switch from the spinlock to a mutex. But turns out that we have no sure whether uart_update_mctrl(), uart_startup() and uart_configure_port() (which calls {get,set}_mctrl()) are called from atomic context or not. This patch adds might_sleep() calls to them in order to help us to find the answer. Please, note that this is just a debug patch to stay in -mm for a while, ie, it's not a submission for mainline kernel. [1] http://marc.theaimsgroup.com/?l=linux-usb-devel&m=114921742628790&w=2 [2] http://lkml.org/lkml/2006/6/13/242 Signed-off-by: Luiz Fernando N. Capitulino diff -purN linux-2.6.17.orig/drivers/serial/serial_core.c linux-2.6.17/drivers/serial/serial_core.c --- linux-2.6.17.orig/drivers/serial/serial_core.c 2006-07-04 16:35:47.796329000 -0300 +++ linux-2.6.17/drivers/serial/serial_core.c 2006-07-04 16:35:47.820333205 -0300 @@ -128,6 +128,8 @@ uart_update_mctrl(struct uart_port *port unsigned long flags; unsigned int old; + might_sleep(); + spin_lock_irqsave(&port->lock, flags); old = port->mctrl; port->mctrl = (old & ~clear) | set; @@ -150,6 +152,8 @@ static int uart_startup(struct uart_stat unsigned long page; int retval = 0; + might_sleep(); + if (info->flags & UIF_INITIALIZED) return 0; @@ -2055,6 +2059,8 @@ uart_configure_port(struct uart_driver * { unsigned int flags; + might_sleep(); + /* * If there isn't a port here, don't do anything further. */ -- Luiz Fernando N. Capitulino