Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756245AbaBUNUO (ORCPT ); Fri, 21 Feb 2014 08:20:14 -0500 Received: from mga02.intel.com ([134.134.136.20]:24096 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756230AbaBUNUL (ORCPT ); Fri, 21 Feb 2014 08:20:11 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,519,1389772800"; d="scan'208";a="479129626" Message-ID: <530754BE.5090301@linux.intel.com> Date: Fri, 21 Feb 2014 15:29:34 +0200 From: Mathias Nyman User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: David Cohen CC: Alan Stern , Greg KH , sarah.a.sharp@linux.intel.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, jianqian Subject: Re: [RFC/PATCH] usb/xhci: avoid kernel panic on xhci_suspend() References: <20140108014550.GA7823@kroah.com> <20140108195334.GB27907@psi-dev26.jf.intel.com> In-Reply-To: <20140108195334.GB27907@psi-dev26.jf.intel.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/08/2014 09:53 PM, David Cohen wrote: > On Wed, Jan 08, 2014 at 10:48:06AM -0500, Alan Stern wrote: >> On Tue, 7 Jan 2014, Greg KH wrote: >> >>> On Tue, Jan 07, 2014 at 05:44:26PM -0800, David Cohen wrote: >>>> From: jianqian >>>> >>>> There is a possible kernel panic faced on xhci_suspend(). >>>> Due to kernel modified the hub autosupend_delay to 0s, after usb1 root >>>> hub finishes initialization, it will trigger runtime_suspend and then >>>> it will trigger xhci runtime suspend. But at that time, if >>>> xhci->shared_hcd is still doing initialization, it is possible to face >>>> null pointer kernel panic in xhci_suspend() function. >>>> >>>> This patch checks if xhci->shared_hcd is null to avoid panic. >>> >>> That sounds like this is a race that should be fixed properly, not just >>> papered over, right? >> >> That was my reaction too. The best way to solve the problem is to >> prevent the USB-2 root hub from suspending until after the USB-3 root >> hub has been registered. > > That makes sense. Thanks for the feedback. > I'll check for a new approach. > Could you check if this patch works for you?: http://marc.info/?l=linux-usb&m=139298822514995&w=2 I'm not able to reproduce the original issue myself -Mathias -- 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/