linux-kernel - Re: [PATCH] PCI: set correct value for iov device before device

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Date:	Fri, 31 May 2013 09:29:12 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Xudong Hao <xudong.hao@...el.com>,
	Jiang Liu <jiang.liu@...wei.com>,
	Yijing Wang <wangyijing@...wei.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH] PCI: set correct value for iov device before device

On Fri 31 May 2013 08:54:24 AM CST, Yinghai Lu wrote:
> On Thu, May 30, 2013 at 4:22 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
>> On Thu, May 30, 2013 at 2:27 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>>> On Wed, May 29, 2013 at 11:04 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>>>> On Wed, May 29, 2013 at 10:45 PM, Xudong Hao <xudong.hao@...el.com> wrote:
>>>>> Since device registering is put into pci_device_add(), it must set value of
>>>>> Virtual Function device's member before the pci_dev is put to device tree. Or
>>>>> some relevant subsystem of driver model such as xen will report a incorrect
>>>>> IOV device to Xen hypervior.
>>>>>
>>>>> Signed-off-by: Xudong Hao <xudong.hao@...el.com>
>>>>> ---
>>>>>  drivers/pci/iov.c | 6 +++---
>>>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>>>>> index c93071d..43d3de9 100644
>>>>> --- a/drivers/pci/iov.c
>>>>> +++ b/drivers/pci/iov.c
>>>>> @@ -110,12 +110,12 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
>>>>>         if (reset)
>>>>>                 __pci_reset_function(virtfn);
>>>>>
>>>>> -       pci_device_add(virtfn, virtfn->bus);
>>>>> -       mutex_unlock(&iov->dev->sriov->lock);
>>>>> -
>>>>>         virtfn->physfn = pci_dev_get(dev);
>>>>>         virtfn->is_virtfn = 1;
>>>>>
>>>>> +       pci_device_add(virtfn, virtfn->bus);
>>>>> +       mutex_unlock(&iov->dev->sriov->lock);
>>>>> +
>>>>>         rc = pci_bus_add_device(virtfn);
>>>>>         sprintf(buf, "virtfn%u", id);
>>>>>         rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
>>>>
>>>> I have similar patch at
>>>> https://patchwork.kernel.org/patch/2562551/
>>>>    [5/7] PCI, ACPI: Don't glue ACPI dev with pci VFs
>>>>
>>>> and Jiang has another one
>>>> https://patchwork.kernel.org/patch/2613481/
>>>>    [v3,part1,10/10] PCI, IOV: hide remove and rescan sysfs interfaces
>>>> for SR-IOV virtual functions
>>>
>>> Bjorn,
>>>
>>> I double check this one, we should split the patch from me or Jiang.
>>
>> I don't know what the sentence above means.
>
> I mean half of patch
> https://patchwork.kernel.org/patch/2562551/
> or half of patch
> https://patchwork.kernel.org/patch/2613481/
>
> just like what Xudong extracted.
>
>>
>>> and the one about set virtfn=1 should be -stable material.
>>
>> I assume you mean that Jiang's "[v3,part1,10/10] PCI, IOV: hide remove
>> and rescan sysfs interfaces for SR-IOV virtual functions" patch does
>> not need to be in v3.10, but it should be marked for -stable.
>
> no half of it, move set virtfn=1 two lines forward.
>
>>
>> How far back should it go?  v3.9+?
>
> yes. v3.9+
>
>>
>>> That will address another problem that is caused by
>>> moving device_add from pci_bus_add_device to pci_device_add.
>>
>> I assume you're talking about a problem caused by 4f535093 ("PCI: Put
>> pci_dev in device tree as early as possible").  That commit appeared
>> in v3.9.
>
> yes.
>
>>
>> If we're asking to add the "hide remove and rescan sysfs interfaces"
>> patch to the v3.9 stable series, we should have a description of
>> exactly what problem it fixes, and ideally, a bugzilla for it.  Can
>> you provide that?
>
> No. that is not what i mean.
>
> That problem have been there when sriov support was added.
>
>>
>> That patch appears to be the only one in the [v3,part1,0/10] series
>> that actually directly fixes an issue, so it would be nice to have
>> more specifics in that changelog to begin with.  The other patches in
>> that series appear to to be cleanups and preparation for the real
>> fixes that will come later.
>
> yes. even should be separated from that patchset.
>
> Yinghai
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Hi Bjorn and Yinghai,
       I think it's ok to separate out the bugfix part.
      We found this issue when implementing the mechanism to hide 
"remove"
sysfs entry for PCI virtual functions because it depends on "is_virtfn" 
flag to
hide "remove" sysfs entry. Actually I didn't realize it also fixes 
other issues
when making this change.
      Sorry for the inconvenience!
Gerry

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