[BART] generation_mode as a kwarg not a class attribute (#3278)

src/transformers/modeling_utils.py

@@ -846,7 +846,6 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin):
             attention_mask = attention_mask.contiguous().view(
                 effective_batch_size * num_beams, input_ids_len
             )  # shape: (batch_size * num_return_sequences * num_beams, cur_len)
-
         if self.config.is_encoder_decoder:
             assert bos_token_id is not None, "Encoder Decoder Models need to have a bos_token_id"
             # encoder decoder need to start with empty input_ids and copy the input_ids to encoder_inputs
@@ -859,9 +858,6 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin):
             )
             cur_len = 1
 
-            # put model in generation mode if it has one
-            if hasattr(self.model, "decoder") and hasattr(self.model.decoder, "generation_mode"):
-                self.model.decoder.generation_mode = True
         else:
             encoder_inputs = None
             cur_len = input_ids.shape[-1]