Xen devel - Mar 2009 - [PATCH] Test tap devices in testDeviceComplete()

Hi,

XendDomainInfo.testDeviceComplete() should check block devices have shutdown
correctly but it only considers vbd class devices and ignores tap devices. The
attached patch changes testDeviceComplete() to wait for both vbd and tap
devices to be shutdown correctly.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>


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On Tuesday 10 March 2009 10:19:23 Jiri Denemark wrote:
> Hi,
>
> XendDomainInfo.testDeviceComplete() should check block devices have
> shutdown correctly but it only considers vbd class devices and ignores tap
> devices. The attached patch changes testDeviceComplete() to wait for both
> vbd and tap devices to be shutdown correctly.
Has this also been tested with PV guests ?  In that case, there are no tap 
devices to shutdown.

Christoph

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> > XendDomainInfo.testDeviceComplete() should check block devices have
> > shutdown correctly but it only considers vbd class devices and ignores
tap
> > devices. The attached patch changes testDeviceComplete() to wait for
both
> > vbd and tap devices to be shutdown correctly.
> 
> Has this also been tested with PV guests ?  In that case, there are no tap 
> devices to shutdown.
Hmm, testDeviceComplete() is called after _releaseDevices(), which destroys
all devices. And even for a PV guest, I can see tap devices in
/vm/UUID/device/tap tree in xenstore.

vm = ""
 0829a755-d2ed-607e-5847-ce9ec19e7422 = ""
  image = "(linux (kernel ) (videoram 4) (notes..."
   ostype = "linux"
   kernel = "/var/run/xend/boot/boot_kernel.QsXCO7"
   cmdline = "ro root=LABEL=/ selinux=0"
   ramdisk = "/var/run/xend/boot/boot_ramdisk.UzyMl2"
  device = ""
   tap = ""
    51712 = ""
     frontend = "/local/domain/2/device/vbd/51712"
     frontend-id = "2"
     backend-id = "0"
     backend = "/local/domain/0/backend/tap/2/51712"

That is, that device will be destroyed by _releaseDevices although not tested
by testDeviceComplete to be completed.

Anyway, this is a bit hard to test, as this code patch is only used when
guest''s kernel lacks SUSPEND_CANCEL feature, which is present in
current Xen
kernels. While, I have a kernel without this feature, it also lacks some other
parts and the guest crashes...

On the other hand, I tested this on older Xen tools which match the kernel.
This code path hasn''t really changed since than.

Jirka

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On 10/03/2009 09:31, "Christoph Egger" <Christoph.Egger@amd.com>
wrote:
>> XendDomainInfo.testDeviceComplete() should check block devices have
>> shutdown correctly but it only considers vbd class devices and ignores
tap
>> devices. The attached patch changes testDeviceComplete() to wait for
both
>> vbd and tap devices to be shutdown correctly.
> 
> Has this also been tested with PV guests ?  In that case, there are no tap
> devices to shutdown.
Tap vs vbd is orthogional to PV vs HVM. Either type of guest can use either
type of storage backend. This detail is hidden from blkfront.

 -- Keir



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