tools: ynl: fix pylint global variable related warnings

Refactor to avoid using global variables to fix the following pylint
issues:

- invalid-name
- global-statement
- global-variable-not-assigned

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20260108161339.29166-7-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/pyynl/lib/nlspec.py

@@ -13,10 +13,6 @@ import os
 import yaml as pyyaml
 
 
-# To be loaded dynamically as needed
-jsonschema = None
-
-
 class SpecException(Exception):
     """Netlink spec exception.
     """
@@ -439,6 +435,10 @@ class SpecFamily(SpecElement):
         mcast_groups  dict of all multicast groups (index by name)
         kernel_family   dict of kernel family attributes
     """
+
+    # To be loaded dynamically as needed
+    jsonschema = None
+
     def __init__(self, spec_path, schema_path=None, exclude_ops=None):
         with open(spec_path, "r", encoding='utf-8') as stream:
             prefix = '# SPDX-License-Identifier: '
@@ -463,15 +463,13 @@ class SpecFamily(SpecElement):
         if schema_path is None:
             schema_path = os.path.dirname(os.path.dirname(spec_path)) + f'/{self.proto}.yaml'
         if schema_path:
-            global jsonschema
-
             with open(schema_path, "r", encoding='utf-8') as stream:
                 schema = pyyaml.safe_load(stream)
 
-            if jsonschema is None:
-                jsonschema = importlib.import_module("jsonschema")
+            if SpecFamily.jsonschema is None:
+                SpecFamily.jsonschema = importlib.import_module("jsonschema")
 
-            jsonschema.validate(self.yaml, schema)
+            SpecFamily.jsonschema.validate(self.yaml, schema)
 
         self.attr_sets = collections.OrderedDict()
         self.sub_msgs = collections.OrderedDict()

tools/net/ynl/pyynl/lib/ynl.py

@@ -320,9 +320,6 @@ class NlMsgs:
         yield from self.msgs
 
 
-genl_family_name_to_id = None
-
-
 def _genl_msg(nl_type, nl_flags, genl_cmd, genl_version, seq=None):
     # we prepend length in _genl_msg_finalize()
     if seq is None:
@@ -338,6 +335,8 @@ def _genl_msg_finalize(msg):
 
 # pylint: disable=too-many-nested-blocks
 def _genl_load_families():
+    genl_family_name_to_id = {}
+
     with socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, Netlink.NETLINK_GENERIC) as sock:
         sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
 
@@ -348,18 +347,14 @@ def _genl_load_families():
 
         sock.send(msg, 0)
 
-        global genl_family_name_to_id
-        genl_family_name_to_id = dict()
-
         while True:
             reply = sock.recv(128 * 1024)
             nms = NlMsgs(reply)
             for nl_msg in nms:
                 if nl_msg.error:
-                    print("Netlink error:", nl_msg.error)
-                    return
+                    raise YnlException(f"Netlink error: {nl_msg.error}")
                 if nl_msg.done:
-                    return
+                    return genl_family_name_to_id
 
                 gm = GenlMsg(nl_msg)
                 fam = {}
@@ -439,15 +434,16 @@ class NetlinkProtocol:
 
 
 class GenlProtocol(NetlinkProtocol):
+    genl_family_name_to_id = {}
+
     def __init__(self, family_name):
         super().__init__(family_name, Netlink.NETLINK_GENERIC)
 
-        global genl_family_name_to_id
-        if genl_family_name_to_id is None:
-            _genl_load_families()
+        if not GenlProtocol.genl_family_name_to_id:
+            GenlProtocol.genl_family_name_to_id = _genl_load_families()
 
-        self.genl_family = genl_family_name_to_id[family_name]
-        self.family_id = genl_family_name_to_id[family_name]['id']
+        self.genl_family = GenlProtocol.genl_family_name_to_id[family_name]
+        self.family_id = GenlProtocol.genl_family_name_to_id[family_name]['id']
 
     def message(self, flags, command, version, seq=None):
         nlmsg = self._message(self.family_id, flags, seq)