[BugFix][QWEN-VL]fix wrong apply_rotary_emb_torch selection introduced by #24642 (#26123)

Signed-off-by: Chendi Xue <Chendi.Xue@intel.com>
Signed-off-by: Chendi.Xue <chendi.xue@intel.com>
Co-authored-by: Roger Wang <hey@rogerw.io>

Author: xuechendi

vllm/model_executor/layers/rotary_embedding/common.py

@@ -4,7 +4,7 @@
 import math
 from functools import cache
 from importlib.util import find_spec
-from typing import Callable
+from typing import Callable, Optional
 
 import torch
 
@@ -72,7 +72,9 @@ def apply_rotary_emb_dispatch(x: torch.Tensor, cos: torch.Tensor,
 
 
 @cache
-def dispatch_rotary_emb_function() -> Callable[..., torch.Tensor]:
+def dispatch_rotary_emb_function(
+    default: Optional[Callable[..., torch.Tensor]] = None
+) -> Callable[..., torch.Tensor]:
     if current_platform.is_cuda():
         return apply_rotary_emb
 
@@ -85,7 +87,10 @@ def dispatch_rotary_emb_function() -> Callable[..., torch.Tensor]:
                 "flash_attn is not installed. Falling back to PyTorch "
                 "implementation for rotary embeddings.")
 
-    return apply_rotary_emb_torch
+    if default is not None:
+        return default
+    else:
+        return apply_rotary_emb_torch
 
 
 # yarn functions

vllm/model_executor/models/qwen2_vl.py

@@ -276,7 +276,8 @@ def apply_rotary_emb_torch(x: torch.Tensor,
 
 def apply_rotary_pos_emb_vision(t: torch.Tensor,
                                 freqs: torch.Tensor) -> torch.Tensor:
-    rotary_emb_function = dispatch_rotary_emb_function()
+    rotary_emb_function = dispatch_rotary_emb_function(
+        default=apply_rotary_emb_torch)
     t_ = t.float()
     cos = freqs.cos()
     sin = freqs.sin()