[Model] Update pooling model interface (#21058)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/model_executor/models/gpt2.py

@@ -40,9 +40,8 @@ from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.layers.vocab_parallel_embedding import (
     ParallelLMHead, VocabParallelEmbedding)
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
-from vllm.model_executor.pooling_metadata import PoolingMetadata
 from vllm.model_executor.sampling_metadata import SamplingMetadata
-from vllm.sequence import IntermediateTensors, PoolerOutput
+from vllm.sequence import IntermediateTensors
 
 from ..layers.pooler import Pooler, PoolingType
 from .interfaces import SupportsPP
@@ -332,6 +331,8 @@ class GPT2ForSequenceClassification(nn.Module):
         _pooler: An instance of Pooler used for pooling operations.
     """
 
+    is_pooling_model = True
+
     def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
         super().__init__()
         config = vllm_config.model_config.hf_config
@@ -339,7 +340,7 @@ class GPT2ForSequenceClassification(nn.Module):
                                      prefix=maybe_prefix(prefix, "gpt2"))
         self.score = nn.Linear(config.n_embd, config.num_labels, bias=False)
         pooler_config = vllm_config.model_config.pooler_config
-        self._pooler = Pooler.from_config_with_defaults(
+        self.pooler = Pooler.from_config_with_defaults(
             pooler_config,
             pooling_type=PoolingType.LAST,
             normalize=False,
@@ -349,13 +350,6 @@ class GPT2ForSequenceClassification(nn.Module):
         loader = AutoWeightsLoader(self)
         return loader.load_weights(weights)
 
-    def pooler(
-        self,
-        hidden_states: torch.Tensor,
-        pooling_metadata: PoolingMetadata,
-    ) -> Optional[PoolerOutput]:
-        return self._pooler(hidden_states, pooling_metadata)
-
     def forward(
         self,
         input_ids: torch.Tensor,