[DLPACK] fix flaky ctypes support (#2759)

python/tvm/_ffi/_ctypes/ndarray.py

@@ -24,6 +24,8 @@ def _from_dlpack(dltensor):
     dltensor = ctypes.py_object(dltensor)
     if ctypes.pythonapi.PyCapsule_IsValid(dltensor, _c_str_dltensor):
         ptr = ctypes.pythonapi.PyCapsule_GetPointer(dltensor, _c_str_dltensor)
+        # enforce type to make sure it works for all ctypes
+        ptr = ctypes.cast(ptr, ctypes.c_void_p)
         handle = TVMArrayHandle()
         check_call(_LIB.TVMArrayFromDLPack(ptr, ctypes.byref(handle)))
         ctypes.pythonapi.PyCapsule_SetName(dltensor, _c_str_used_dltensor)
@@ -36,6 +38,8 @@ def _dlpack_deleter(pycapsule):
     pycapsule = ctypes.cast(pycapsule, ctypes.py_object)
     if ctypes.pythonapi.PyCapsule_IsValid(pycapsule, _c_str_dltensor):
         ptr = ctypes.pythonapi.PyCapsule_GetPointer(pycapsule, _c_str_dltensor)
+        # enforce type to make sure it works for all ctypes
+        ptr = ctypes.cast(ctypes.c_void_p, ptr)
         _LIB.TVMDLManagedTensorCallDeleter(ptr)
         ctypes.pythonapi.PyCapsule_SetDestructor(dltensor, TVMPyCapsuleDestructor(0))