From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
sarah.a.sharp@linux.intel.com, dan.j.williams@intel.com,
stable@vger.kernel.org,
David Cohen <david.a.cohen@linux.intel.com>
Subject: Re: [PATCH v3 1/1] xhci: Prevent runtime pm from autosuspending during initialization
Date: Tue, 04 Mar 2014 13:50:55 +0200 [thread overview]
Message-ID: <5315BE1F.8020100@linux.intel.com> (raw)
In-Reply-To: <20140303183733.GA13926@kroah.com>
On 03/03/2014 08:37 PM, Greg KH wrote:
> On Mon, Mar 03, 2014 at 07:30:17PM +0200, Mathias Nyman wrote:
>> xHCI driver has its own pci probe function that will call usb_hcd_pci_probe
>> to register its usb-2 bus, and then continue to manually register the
>> usb-3 bus. usb_hcd_pci_probe does a pm_runtime_put_noidle at the end and
>> might thus trigger a runtime suspend before the usb-3 bus is ready.
>
> What is the result if that happens?
Crashes. Null pointer dereference in xhci_suspend() when touching
xhci->shared_hcd before it's initialized. More info here:
http://marc.info/?l=linux-usb&m=138914518219334&w=2
>
> Is this a regression from 3.13? Or something new for 3.14?
>
According to reporter its been around since 3.7
commit 596d789a211d134dc5f94d1e5957248c204ef850
USB: set hub's default autosuspend delay as 0
But nobody else than the reporter is able to trigger it.
> What platform(s) are affected by this?
David, the reporter (added to cc), mentioned
"This bug happened in a platform with 1 usb3 host controller + 1 usb3
OTG controller" run by some Intel internal group
http://marc.info/?l=linux-usb&m=138915969822029&w=2
David, can you elaborate on the platform?
>> xhci-platform driver is not using usb_hcd_pci_probe to set up
>> busses and should not need to have it's usage count increased during probe.
>
> I didn't think we had any in-kernel users of the xhci-platform driver,
> has that changed and I missed a new platform being added?
>
Not that I'm aware of. I just wanted to point out that this issue is
only a matter on pci enumerated xhci hosts.
-Mathias
next prev parent reply other threads:[~2014-03-04 11:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-03 17:30 [PATCH 0/1] xhci: fixes for 3.14 Mathias Nyman
2014-03-03 17:30 ` [PATCH v3 1/1] xhci: Prevent runtime pm from autosuspending during initialization Mathias Nyman
[not found] ` <20140303183733.GA13926@kroah.com>
2014-03-04 11:50 ` Mathias Nyman [this message]
2014-03-04 17:04 ` Greg KH
2014-03-04 17:35 ` David Cohen
2014-03-04 22:44 ` Sarah Sharp
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