From: Yijing Wang <wangyijing@huawei.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
Yinghai Lu <yinghai@kernel.org>,
Andreas Noever <andreas.noever@gmail.com>,
"Matthew Garrett" <mjg59@srcf.ucam.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [3.11.4] Thunderbolt/PCI unplug oops in pci_pme_list_scan
Date: Wed, 20 Nov 2013 09:39:05 +0800 [thread overview]
Message-ID: <528C12B9.60506@huawei.com> (raw)
In-Reply-To: <CAErSpo7nKXR9NBbjs8K__T2TCONW6N76ytevTH-bxcs-NH3+Zg@mail.gmail.com>
On 2013/11/20 9:20, Bjorn Helgaas wrote:
> On Tue, Nov 19, 2013 at 6:14 PM, Yijing Wang <wangyijing@huawei.com> wrote:
>>>>> [bhelgaas: changelog, tag for stable]
>>>>> Reported-by: David Bulkow <David.Bulkow@stratus.com>
>>>>> Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com>
>>>>> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
>>>>> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>>>>> CC: stable@vger.kernel.org # v2.6.32+
>>>>
>>>> Hi Bjorn,
>>>> This issue in X86 seems to be introduced after commit 928bea9 "PCI: Delay enabling bridges until they're needed"
>>>> So this patch needs to back port to 2.6.32+ ?
>>>
>>> 928bea9 might have made it more visible, but the underlying problem is that
>>> we enable the device once in the probe path, and disable it twice in the
>>> remove path. That problem exists in 2.6.32.61:
>>>
>>> pcie_portdrv_probe # .probe() method
>>> pcie_port_device_register
>>> pci_enable_device <-- enable
>>>
>>> pcie_portdrv_remove # .remove() method
>>> pcie_port_device_remove
>>> pci_disable_device <-- disable #1
>>> pci_disable_device <-- disable #2
>>
>> During assign unassigned resources, we also enable the port device,
>>
>> fs_initcall(pcibios_assign_resources);
>> pci_assign_unassigned_resources;
>> pci_enable_bridges()
>> pci_enable_device()
>>
>>
>> So I think before the commit 928bea9 , the pci bridge device enable and disable is symmetrical.
>> After the commit 928bea9, we only enable bridge once, but still remove twice.
>
> The port driver should be symmetrical, regardless of what happens
> outside it. We have to be able to bind/unbind/bind/unbind
> indefinitely.
>
> Do you think the patch is a problem for current upstream, or are you
> just saying it doesn't need to be backported as far as 2.6.32? I
> frankly don't care that much if those old kernels pick it up or not.
> All I'm saying is that the problem this fixes is present that far
> back.
>
> I'm not really interested in doing a lot more digging about ancient
> kernels, unless you think it's going to break something if applied to
> them.
As you said, this is not a big problem, it's ok for current upstream,
and for 3.4 3.5 3.10 stable tree, it seems just a enable and disable symmetry problem.
I don't find anything unsafe about this even though when we unbind pcie port driver,
the pcie port maybe still enable. I have no objection to backport it to ancient kernels. :)
Thanks!
Yijing.
>
> Bjorn
>
>
--
Thanks!
Yijing
next prev parent reply other threads:[~2013-11-20 1:40 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-14 22:47 [3.11.4] Thunderbolt/PCI unplug oops in pci_pme_list_scan Andreas Noever
2013-10-14 23:50 ` Bjorn Helgaas
2013-10-15 2:44 ` Matthew Garrett
2013-10-16 20:21 ` Bjorn Helgaas
2013-10-17 13:59 ` Andreas Noever
2013-10-23 3:32 ` Bjorn Helgaas
2013-10-24 5:53 ` Yinghai Lu
2013-10-25 3:33 ` Bjorn Helgaas
2013-10-25 5:13 ` Yinghai Lu
2013-10-25 5:28 ` Yinghai Lu
2013-10-25 23:01 ` Bjorn Helgaas
2013-10-27 0:39 ` Andreas Noever
2013-11-15 11:52 ` Mika Westerberg
2013-11-19 1:33 ` Bjorn Helgaas
2013-11-19 1:54 ` Yijing Wang
2013-11-19 17:18 ` Bjorn Helgaas
2013-11-20 1:14 ` Yijing Wang
2013-11-20 1:20 ` Bjorn Helgaas
2013-11-20 1:39 ` Yijing Wang [this message]
2013-11-19 10:06 ` Mika Westerberg
2013-10-30 7:57 ` Yijing Wang
2013-10-31 6:48 ` Yinghai Lu
2013-10-23 23:53 ` Bjorn Helgaas
2013-10-29 3:30 ` Bjorn Helgaas
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