Raise an OSError if a read is already pending

python/local/ovms_module/ovms/ptd/_vmsptd.pyx

@@ -364,5 +364,5 @@
     "status, res = readw(handler)"
     cdef int efn = EFN_C_ENF
     cdef unsigned short s
-    # if a read is already pending, wait for completion
+    # if a read is already pending, raise an Error
     if handler.handler.read_status != 0:
@@ -368,7 +368,5 @@
     if handler.handler.read_status != 0:
-        while handler.handler.read_status != 2:
-            s = sys_hiber()
-        s = SS__NORMAL
+        raise OSError("Read already active on this Ptd")
     handler.handler.read_status = 0
     (<ptd_buf *>(handler.handler.read_buf)).status = 0
     with nogil: