migration: failover: continue to wait card unplug on error

If the user cancels the migration in the unplug-wait state,
QEMU will try to plug back the card and this fails because the card
is partially unplugged.
To avoid the problem, continue to wait the card unplug, but to
allow the migration to be canceled if the card never finishes to unplug
use a timeout.

Bug: https://bugzilla.redhat.com/show_bug.cgi?id=1976852
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210629155007.629086-3-lvivier@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/migration/migration.c b/migration/migration.c
index dbc484c802f9eab4c6dae64e7142a09cadd9d0f8..5ff7ba9d5c1f9192d0474469dce348e9eec91331 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3691,6 +3691,17 @@ static void qemu_savevm_wait_unplug(MigrationState *s, int old_state,
                qemu_savevm_state_guest_unplug_pending()) {
             qemu_sem_timedwait(&s->wait_unplug_sem, 250);
         }
+        if (s->state != MIGRATION_STATUS_WAIT_UNPLUG) {
+            int timeout = 120; /* 30 seconds */
+            /*
+             * migration has been canceled
+             * but as we have started an unplug we must wait the end
+             * to be able to plug back the card
+             */
+            while (timeout-- && qemu_savevm_state_guest_unplug_pending()) {
+                qemu_sem_timedwait(&s->wait_unplug_sem, 250);
+            }
+        }
 
         migrate_set_state(&s->state, MIGRATION_STATUS_WAIT_UNPLUG, new_state);
     } else {