tests: Fix d2c test

Cache attach operation is not supposed to complete unless all the d2c
requests are completed, thus need to handle it asynchronously.

Signed-off-by: Robert Baldyga <robert.baldyga@huawei.com>

tests/functional/pyocf/types/cache.py

@@ -569,7 +569,7 @@ class Cache:
     def free_device_config(self, cfg):
         lib = OcfLib.getInstance().ocf_volume_destroy(cfg._volume)
 
-    def attach_device(
+    def attach_device_async(
         self,
         device,
         force=False,
@@ -593,15 +593,40 @@ class Cache:
 
         self.write_lock()
 
-        c = OcfCompletion([("cache", c_void_p), ("priv", c_void_p), ("error", c_int)])
+        def callback(c):
+            self.write_unlock()
+            self.free_device_config(device_config)
+
+        c = OcfCompletion(
+            [("cache", c_void_p), ("priv", c_void_p), ("error", c_int)],
+            callback=callback
+        )
 
         self.owner.lib.ocf_mngt_cache_attach(self.cache_handle, byref(attach_cfg), c, None)
+
+        return c
+
+    def attach_device(
+        self,
+        device,
+        force=False,
+        perform_test=False,
+        cache_line_size=None,
+        open_cores=False,
+        disable_cleaner=False,
+    ):
+
+        c = self.attach_device_async(
+            device,
+            force,
+            perform_test,
+            cache_line_size,
+            open_cores,
+            disable_cleaner
+        )
+
         c.wait()
 
-        self.write_unlock()
-
-        self.free_device_config(device_config)
-
         if c.results["error"]:
             raise OcfError(
                 f"Attaching cache device failed",

tests/functional/pyocf/types/shared.py

@@ -83,7 +83,7 @@ class OcfCompletion:
             except KeyError:
                 raise KeyError(f"No completion argument {key} specified")
 
-    def __init__(self, completion_args: list, context=None):
+    def __init__(self, completion_args: list, context=None, callback=None):
         """
         Provide ctypes arg list, and optionally index of status argument in
         completion function which will be extracted (default - last argument).
@@ -95,6 +95,7 @@ class OcfCompletion:
         self.results = OcfCompletion.CompletionResult(completion_args)
         self._as_parameter_ = self.callback
         self.context = context
+        self.user_callback = callback
 
     @property
     def callback(self):
@@ -102,6 +103,8 @@ class OcfCompletion:
         def complete(*args):
             self.results.results = args
             self.e.set()
+            if self.user_callback:
+                self.user_callback(self)
 
         return complete