[Bug 1829380] Re: race condition between vhost_net_stop and CHR_EVENT_CLOSED on shutdown crashes qemu (fix regression)

[Dan Streetman]

ocata:

I was able to reproduce the regression by rebooting the guest - I could
not reproduce it any other way, by attaching/removing interface(s),
setting their link up/down from the host side or from the guest side,
adding/removing them to a bridge on the host, etc.  On reboot, with qemu
1:2.8+dfsg-3ubuntu2.9~cloud5.1, after 2 reboots I was able to reproduce
the guest being unable to use the interface.  I stopped the guest,
upgraded to 1:2.8+dfsg-3ubuntu2.9~cloud6, and repeated the test, and the
guest had no problems even after 10 reboots.

** Description changed:

  [impact]
  
  this bug is to track re-uploading the fix for bug 1823458 plus a patch
  to fix a regression it introduced.
  
  instead of copying the details from bug 1823458, please see that bug for
  impact and testcase.
  
  [test case]
  
- see bug 1823458
+ see bug 1823458 for the original bug test case
+ 
+ for the regression test case from bug 1829245, rebooting the guest will
+ result in the guest being unable to use the interface (possibly a couple
+ reboots are needed to reproduce if the interface still works after the
+ first reboot).
  
  [regression potential]
  
  see bug 1823458
  
  additionally, the regression from the last fix is in bug 1829245.
  
  the change is in code where this still has the regression potential of
  causing guest networking to fail.

** Tags removed: verification-ocata-needed
** Tags added: verification-ocata-done

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https://bugs.launchpad.net/bugs/1829380

Title:
  race condition between vhost_net_stop and CHR_EVENT_CLOSED on shutdown
  crashes qemu (fix regression)

Status in Ubuntu Cloud Archive:
  Invalid
Status in Ubuntu Cloud Archive mitaka series:
  Triaged
Status in Ubuntu Cloud Archive ocata series:
  Fix Released
Status in qemu package in Ubuntu:
  Invalid
Status in qemu source package in Xenial:
  In Progress

Bug description:
  [impact]

  this bug is to track re-uploading the fix for bug 1823458 plus a patch
  to fix a regression it introduced.

  instead of copying the details from bug 1823458, please see that bug
  for impact and testcase.

  [test case]

  see bug 1823458 for the original bug test case

  for the regression test case from bug 1829245, rebooting the guest
  will result in the guest being unable to use the interface (possibly a
  couple reboots are needed to reproduce if the interface still works
  after the first reboot).

  [regression potential]

  see bug 1823458

  additionally, the regression from the last fix is in bug 1829245.

  the change is in code where this still has the regression potential of
  causing guest networking to fail.

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