From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: David Cohen <david.a.cohen@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Greg KH <gregkh@linuxfoundation.org>,
sarah.a.sharp@linux.intel.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, jianqian <jianqiang.tang@intel.com>
Subject: Re: [RFC/PATCH] usb/xhci: avoid kernel panic on xhci_suspend()
Date: Fri, 21 Feb 2014 15:29:34 +0200 [thread overview]
Message-ID: <530754BE.5090301@linux.intel.com> (raw)
In-Reply-To: <20140108195334.GB27907@psi-dev26.jf.intel.com>
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 <jianqiang.tang@intel.com>
>>>>
>>>> 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
next prev parent reply other threads:[~2014-02-21 13:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-08 1:44 [RFC/PATCH] usb/xhci: avoid kernel panic on xhci_suspend() David Cohen
2014-01-08 1:45 ` Greg KH
2014-01-08 15:48 ` Alan Stern
2014-01-08 19:53 ` David Cohen
2014-02-21 13:29 ` Mathias Nyman [this message]
2014-01-08 1:46 ` Greg KH
2014-01-08 3:49 ` Tang, Jianqiang
2014-01-08 4:16 ` Greg KH
2014-01-08 5:45 ` David Cohen
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