migration: store end_time in a local variable

Signed-off-by: NJuan Quintela <quintela@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NOrit Wasserman <owasserm@redhat.com>

migration.c

@@ -329,6 +329,7 @@ static void migrate_fd_put_ready(void *opaque)
         migrate_fd_error(s);
     } else if (ret == 1) {
         int old_vm_running = runstate_is_running();
+        int64_t end_time;
 
         DPRINTF("done iterating\n");
         qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
@@ -339,7 +340,8 @@ static void migrate_fd_put_ready(void *opaque)
         } else {
             migrate_fd_completed(s);
         }
-        s->total_time = qemu_get_clock_ms(rt_clock) - s->total_time;
+        end_time = qemu_get_clock_ms(rt_clock);
+        s->total_time = end_time - s->total_time;
         if (s->state != MIG_STATE_COMPLETED) {
             if (old_vm_running) {
                 vm_start();