Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968413AbXJSWFo (ORCPT ); Fri, 19 Oct 2007 18:05:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S968361AbXJSWFa (ORCPT ); Fri, 19 Oct 2007 18:05:30 -0400 Received: from twin.jikos.cz ([213.151.79.26]:60561 "EHLO twin.jikos.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968362AbXJSWF3 (ORCPT ); Fri, 19 Oct 2007 18:05:29 -0400 Date: Sat, 20 Oct 2007 00:05:19 +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: <4719235E.9030507@lwfinger.net> Message-ID: References: <4718D469.2080606@lwfinger.net> <4719235E.9030507@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: 1655 Lines: 48 On Fri, 19 Oct 2007, Larry Finger wrote: > As I said earlier, the lock problem went away; however, I get the > following two kernel warnings: That's because I messed up the patch, sorry. The one below should work better. 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..9eb4a65 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); + spin_unlock_irqrestore(&port->lock, flags); 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/