Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933903AbYBTQWc (ORCPT ); Wed, 20 Feb 2008 11:22:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765416AbYBTQLP (ORCPT ); Wed, 20 Feb 2008 11:11:15 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:47140 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1765057AbYBTQKE (ORCPT ); Wed, 20 Feb 2008 11:10:04 -0500 Date: Wed, 20 Feb 2008 11:10:01 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: David Brownell cc: David Miller , , , Subject: Re: USB OOPS 2.6.25-rc2-git1 In-Reply-To: <200802191619.55207.david-b@pacbell.net> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 43 On Tue, 19 Feb 2008, David Brownell wrote: > Please try that diagnostic patch I sent ... with CONFIG_USB_DEBUG. > > Near as I can tell this is caused by some hardware oddity that needs > to be worked around. We seem to be at stage where we've fixed some > problems, nudging code paths around so another one shows up, and have > incidentally had a new silicion-specific hardware erratum reported > in this area. So more info is needed... > > A quick anti-oops patch is appended, it should work OK on top of that > diagnostic patch, but won't necessarily resolve the underlying problem. > > - Dave > > > --- g26.orig/drivers/usb/host/ehci-q.c 2008-02-19 16:15:04.000000000 -0800 > +++ g26/drivers/usb/host/ehci-q.c 2008-02-19 16:15:59.000000000 -0800 > @@ -993,6 +993,11 @@ static void end_unlink_async (struct ehc > > iaa_watchdog_done(ehci); > > + if (!qh) { > + WARN_ON(1); > + return; > + } > + It will be interesting to see the stack dump. As far as I can tell, there are two pathways which could lead qh being NULL. One is the IAA hardware peculiarity (setting the status bit very late, after the watchdog timer has already expired), and the other is in unlink_async() if the controller isn't running. That second one may be just a simple bug -- I doubt it would show up unless the controller got a fatal error and stopped. Alan Stern -- 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/