About rawiobase_readall.patch: why do you use PyObject_Size() if you know chunks is a list? PyList_GET_SIZE is much more efficient.

About bufferedreader_readall.patch:

+            PyBytes_Concat(&data, all);
+            if (data == NULL)
+                return NULL;

You must Py_DECREF(all) first.

Also, you should check that "all" is either None or a bytes object.