[libvirt] [PATCH] fix the failure of nodedev-reattach caused by the variables from nodedev-attach

[Guannan Ren]

On 07/01/2011 11:30 PM, ghostwcy wrote:
> At 2011-7-1 18:24, Guannan Ren write:
>> the "virsh nodedev-reattch" command could return successfully, but 
>> the pci device is still
>> bound to pci-stub driver. The reason is noddev-reattach trys to use 
>> the variables set by
>> nodedev-dettach commands. Becuase these variables is not persistent, 
>> this is not we expected.
>> the patch try to fix it.
>
> I do not agree with this patch. You should read this mail:
> https://www.redhat.com/archives/libvir-list/2011-April/msg00315.html
>
> This patch will cause regression about hotpluging host pci device.
>
> I think the problem is that: the init value of these variables is wrong.
> We can fix this bug by modifing pciGetDevice() or its caller.
>
>>

        I read the patch, it introduced the mechanism to check whether 
the device is bound to
    pci-stub when we write dev-id to new_id if a new device with this ID 
is hotpluggged, or if
    a probe is triggered for such a device,  I think my patch kept it 
working.
        The overall idea is as follows:
             If the device is already bound to pci-stub, then do nothing.
             If not,  try to write dev-id to "new_id", then check the 
state of its driver(hotplug issue)
             Unbind from its original driver , then bind to pci-stub driver
             Anyway, we should write dev-id to "remove_id" to protect 
the device from causing
                  problems when reattaching it.
    About fixing the problem from pciGetDevice(),  unless we feedback 
the state of pci device to
    libvirtd  but I don't think it is easier.