On Fri, Oct 11, 2019 at 06:11:33PM +0100, Dr. David Alan Gilbert wrote:
* Jens Freimann (jfreim...@redhat.com) wrote:
This patch adds a new migration state called wait-unplug. It is entered
after the SETUP state and will transition into ACTIVE once all devices
were succesfully unplugged from the guest.
So if a guest doesn't respond or takes long to honor the unplug request
the user will see the migration state 'wait-unplug'.
In the migration thread we query failover devices if they're are still
pending the guest unplug. When all are unplugged the migration
continues. We give it a defined number of iterations including small
waiting periods before we proceed.
Signed-off-by: Jens Freimann <jfreim...@redhat.com>
[..]
@@ -3260,6 +3271,27 @@ static void *migration_thread(void *opaque)
qemu_savevm_state_setup(s->to_dst_file);
+ migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
+ MIGRATION_STATUS_WAIT_UNPLUG);
I think I'd prefer if you only went into this state if you had any
devices that were going to need unplugging.
Sure, that makes sense. I'll change it.
+ while (i < FAILOVER_UNPLUG_RETRIES &&
+ s->state == MIGRATION_STATUS_WAIT_UNPLUG) {
+ i++;
+ qemu_sem_timedwait(&s->wait_unplug_sem, FAILOVER_GUEST_UNPLUG_WAIT);
+ all_unplugged = qemu_savevm_state_guest_unplug_pending();
+ if (all_unplugged) {
+ break;
+ }
+ }
+
+ if (all_unplugged) {
+ migrate_set_state(&s->state, MIGRATION_STATUS_WAIT_UNPLUG,
+ MIGRATION_STATUS_ACTIVE);
+ } else {
+ migrate_set_state(&s->state, MIGRATION_STATUS_WAIT_UNPLUG,
+ MIGRATION_STATUS_CANCELLING);
+ }
I think you can get rid of both the timeout and the count and just make
sure that migrate_cancel works at this point.
I see, I need to add the new state to migration_is_setup_or_active() or
a cancel won't work.
This pushes the problem up a layer, which I think is fine.
Seems good to me. To be clear, you're saying I should just poll on
the device unplugged state? Like
while (s->state == MIGRATION_STATUS_WAIT_UNPLUG &&
!qemu_savevm_state_guest_unplug_pending()) {
_ /* This block intentionally left blank */
}
regards,
Jens
