Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966696AbXJSVG5 (ORCPT ); Fri, 19 Oct 2007 17:06:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966586AbXJSVGf (ORCPT ); Fri, 19 Oct 2007 17:06:35 -0400 Received: from twin.jikos.cz ([213.151.79.26]:54692 "EHLO twin.jikos.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765206AbXJSVGe (ORCPT ); Fri, 19 Oct 2007 17:06:34 -0400 Date: Fri, 19 Oct 2007 23:06:18 +0200 (CEST) From: Jiri Kosina To: Larry Finger cc: LKML , Greg Kroah-Hartman , linux-usb-devel@lists.sourceforge.net Subject: Re: Locking problem in usbserial with 2.6.23-git 5a34417f In-Reply-To: <4718D469.2080606@lwfinger.net> Message-ID: References: <4718D469.2080606@lwfinger.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1821 Lines: 49 On Fri, 19 Oct 2007, Larry Finger wrote: > While attempting to configure a new USB modem, the following locking > problem occurred. In addition, shortly after this problem occurred, the > computer froze. The log data starts at the point that usbserial was > loaded and contains everything that was written to disk before the > machine locked up. Some info may be missing from the end of the stack > dump. I guess this one is needed. From: Jiri Kosina USB: usbserial - fix potential deadlock between write() and irq usb_serial_generic_write() doesn't disable interrupts when taking port->lock, and could therefore deadlock with usb_serial_generic_read_bulk_callback() being called from interrupt, taking the same lock. Fix it. Signed-off-by: Jiri Kosina diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index 88a2c7d..6f8d712 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -208,14 +208,15 @@ int usb_serial_generic_write(struct usb_serial_port *port, const unsigned char * /* only do something if we have a bulk out endpoint */ if (serial->num_bulk_out) { - spin_lock_bh(&port->lock); + unsigned long flags; + spin_lock_irqsave(&port->lock, flags); if (port->write_urb_busy) { spin_unlock_bh(&port->lock); dbg("%s - already writing", __FUNCTION__); return 0; } port->write_urb_busy = 1; - spin_unlock_bh(&port->lock); + spin_unlock_irqrestore(&port->lock, flags); count = (count > port->bulk_out_size) ? port->bulk_out_size : count; - 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/