fix: free resources when a suite run is done

Add missing code to free resources, not upon program exit, but when a suite is
done.

This allows running more than one suite in a row.

Also add a check to not attempt to free if there is nothing to be freed, to
avoid a regression test failure triggered when a suite exits without reserving
anything.

Change-Id: Ic017a1cf07052f5e48812c8553fba6f972d280f0
Related: OS#2301

src/osmo_gsm_tester/resource.py

@@ -494,7 +494,8 @@ class ReservedResources(log.Origin):
                     my_item.pop(USED_KEY)
 
     def free(self):
-        self.resources_pool.free(self.origin, self.reserved)
+        if self.reserved:
+            self.resources_pool.free(self.origin, self.reserved)
         self.reserved = None
 
     def counts(self):

src/osmo_gsm_tester/suite.py

@@ -248,6 +248,7 @@ class SuiteRun(log.Origin):
             # base exception is raised. Make sure to stop processes in this
             # finally section. Resources are automatically freed with 'atexit'.
             self.stop_processes()
+            self.free_resources()
         event_loop.unregister_poll_func(self.poll)
         self.duration = time.time() - self.start_timestamp
         if self.test_failed_ctr:
@@ -268,6 +269,11 @@ class SuiteRun(log.Origin):
         for process in self._processes:
             process.terminate()
 
+    def free_resources(self):
+        if self.reserved_resources is None:
+            return
+        self.reserved_resources.free()
+
     def ip_address(self):
         return self.reserved_resources.get(resource.R_IP_ADDRESS)