From: Jakub Kicinski <kuba@kernel.org>
Date: Wed, 23 Aug 2023 17:30:55 -0700
Subject: tools: ynl-gen: support empty attribute lists
Patch-mainline: v6.6-rc1
Git-commit: 4c8c24e801e60a2b4a6f78401c9b7cb6cbf47cbf
References: jsc#PED-3311

Differentiate between empty list and None for member lists.
New families may want to create request responses with no attribute.
If we treat those the same as None we end up rendering
a full parsing policy in user space, instead of an empty one.

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20230824003056.1436637-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 tools/net/ynl/ynl-gen-c.py |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/tools/net/ynl/ynl-gen-c.py
+++ b/tools/net/ynl/ynl-gen-c.py
@@ -615,7 +615,7 @@ class Struct:
 
         self.attr_list = []
         self.attrs = dict()
-        if type_list:
+        if type_list is not None:
             for t in type_list:
                 self.attr_list.append((t, self.attr_set[t]),)
         else:
@@ -1543,7 +1543,14 @@ def parse_rsp_msg(ri, deref=False):
 
     ri.cw.write_func_prot('int', f'{op_prefix(ri, "reply", deref=deref)}_parse', func_args)
 
-    _multi_parse(ri, ri.struct["reply"], init_lines, local_vars)
+    if ri.struct["reply"].member_list():
+        _multi_parse(ri, ri.struct["reply"], init_lines, local_vars)
+    else:
+        # Empty reply
+        ri.cw.block_start()
+        ri.cw.p('return MNL_CB_OK;')
+        ri.cw.block_end()
+        ri.cw.nl()
 
 
 def print_req(ri):