Fix the torch version parsing logic (#15857)

vllm/utils.py

@@ -53,6 +53,7 @@ import torch.types
 import yaml
 import zmq
 import zmq.asyncio
+from packaging import version
 from packaging.version import Version
 from torch.library import Library
 from typing_extensions import Never, ParamSpec, TypeIs, assert_never
@@ -2580,3 +2581,20 @@ def sha256(input) -> int:
     input_bytes = pickle.dumps(input, protocol=pickle.HIGHEST_PROTOCOL)
     return int.from_bytes(hashlib.sha256(input_bytes).digest(),
                           byteorder="big")
+
+
+def is_torch_equal_or_newer(target: str) -> bool:
+    """Check if the installed torch version is >= the target version.
+
+    Args:
+        target: a version string, like "2.6.0".
+
+    Returns:
+        Whether the condition meets.
+    """
+    try:
+        torch_version = version.parse(str(torch.__version__))
+        return torch_version >= version.parse(target)
+    except Exception:
+        # Fallback to PKG-INFO to load the package info, needed by the doc gen.
+        return Version(importlib.metadata.version('torch')) >= Version(target)