[Spice-devel] [PATCH] migration: Don't assert() if MIGRATE_DATA comes before attaching the agent

[Uri Lublin]

This patch fixes an assert in spice-server code on the
destination side of migration, that happens when
the MIGRATE_DATA message of the main channel arrives
before the (qemu-kvm's) virtio-serial-port device state.
For a more detailed information look at the patch
log message.

Some comments/concerns about this patch:
1. Some more testing needs to be done.
   To test it, the MIGRATE_DATA message needs to arrive first.
   One way to achieve that is to make the migration socket
   between the two hosts slower.
   Another is to add some sleeps in the other path of the code, which
   is what I did.

2. I did encounter migration problems in my testing, with
   upstream code.
   Seems to me it is not due to this patch but to either
   a different migration problem or the code changes made
   to test the patch.
   
3. Theoretically, any virtual device attached to a 
   virtio-serial-bus port, which is a means of 
   communication between the client and the guest,
   should behave the same way. But the implementation
   of main channel (vdagent) is different than the
   implementation of other spice channels that use
   virtio-serial port.

Based on a patch by Christophe.

Uri Lublin (1):
  migration: Don't assert() if MIGRATE_DATA comes before attaching the
    agent

 server/reds.c | 39 ++++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

-- 
1.9.3