[Qemu-devel] [Bug 1779120] [NEW] disk missing in the guest contingently when hotplug several virtio scsi disks consecutively

[贞贵李]

Public bug reported:

Hi, I found a bug that disk missing (not all disks missing ) in the
guest contingently when hotplug several virtio scsi disks consecutively.
After rebooting the guest,the missing disks appear again.

The guest is centos7.3 running on a centos7.3 host and the scsi
controllers are configed with iothread.  The scsi controller xml is
below:

    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver iothread='26'/>
      <alias name='scsi0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' 
function='0x0'/>
    </controller>

If the scsi controllers are configed without iothread,  disks are all
can be seen in the guest when hotplug several virtio scsi disks
consecutively.

I think the biggest difference between them is that scsi controllers
with iothread call virtio_notify_irqfd to notify guest and scsi
controllers without iothread call virtio_notify instead.  What make it
difference? Will interrupts are lost when call virtio_notify_irqfd  due
to  race condition for some unknow reasons? Maybe guys more familiar
with scsi dataplane can help. Thanks for your reply!

** Affects: qemu
     Importance: Undecided
         Status: New

** Description changed:

  Hi, I found a bug that disk missing (not all disks missing ) in the
  guest contingently when hotplug several virtio scsi disks consecutively.
  After rebooting the guest,the missing disks appear again.
  
  The guest is centos7.3 running on a centos7.3 host and the scsi
  controllers are configed with iothread.  The scsi controller xml is
  below:
  
-     <controller type='scsi' index='0' model='virtio-scsi'>
-       <driver iothread='26'/>
-       <alias name='scsi0'/>
-       <address type='pci' domain='0x0000' bus='0x00' slot='0x07' 
function='0x0'/>
-     </controller>
+     <controller type='scsi' index='0' model='virtio-scsi'>
+       <driver iothread='26'/>
+       <alias name='scsi0'/>
+       <address type='pci' domain='0x0000' bus='0x00' slot='0x07' 
function='0x0'/>
+     </controller>
  
- 
- If the scsi controllers are configed without iothread,  disks are all can be 
seen in the guest when hotplug several virtio scsi disks consecutively.
+ If the scsi controllers are configed without iothread,  disks are all
+ can be seen in the guest when hotplug several virtio scsi disks
+ consecutively.
  
  I think the biggest difference between them is that scsi controllers
  with iothread call virtio_notify_irqfd to notify guest and scsi
- controllers without
- 
- iothread call virtio_notify instead.  What make it difference? Will
- interrupts are lost when call virtio_notify_irqfd  due to  race
- condition for some unknow reasons? Maybe guys more familiar with scsi
- dataplane can help. Thanks for your reply!
+ controllers without iothread call virtio_notify instead.  What make it
+ difference? Will interrupts are lost when call virtio_notify_irqfd  due
+ to  race condition for some unknow reasons? Maybe guys more familiar
+ with scsi dataplane can help. Thanks for your reply!

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https://bugs.launchpad.net/bugs/1779120

Title:
  disk missing in the guest contingently when hotplug several virtio
  scsi disks consecutively

Status in QEMU:
  New

Bug description:
  Hi, I found a bug that disk missing (not all disks missing ) in the
  guest contingently when hotplug several virtio scsi disks
  consecutively.  After rebooting the guest,the missing disks appear
  again.

  The guest is centos7.3 running on a centos7.3 host and the scsi
  controllers are configed with iothread.  The scsi controller xml is
  below:

      <controller type='scsi' index='0' model='virtio-scsi'>
        <driver iothread='26'/>
        <alias name='scsi0'/>
        <address type='pci' domain='0x0000' bus='0x00' slot='0x07' 
function='0x0'/>
      </controller>

  If the scsi controllers are configed without iothread,  disks are all
  can be seen in the guest when hotplug several virtio scsi disks
  consecutively.

  I think the biggest difference between them is that scsi controllers
  with iothread call virtio_notify_irqfd to notify guest and scsi
  controllers without iothread call virtio_notify instead.  What make it
  difference? Will interrupts are lost when call virtio_notify_irqfd
  due to  race condition for some unknow reasons? Maybe guys more
  familiar with scsi dataplane can help. Thanks for your reply!

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