Subject: [PATCH net-next 4/5] tools: ynl-gen: support empty attribute lists

From: Jakub Kicinski <[email-masked]>
Date: Wed, 23 Aug 2023 17:30:55 -0700

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.

Signed-off-by: Jakub Kicinski <[email-masked]>
---
 tools/net/ynl/ynl-gen-c.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/net/ynl/ynl-gen-c.py b/tools/net/ynl/ynl-gen-c.py
index 13d06931c045..9209bdcca9c6 100755
--- a/tools/net/ynl/ynl-gen-c.py
+++ b/tools/net/ynl/ynl-gen-c.py
@@ -615,7 +615,7 @@ from lib import SpecFamily, SpecAttrSet, SpecAttr, SpecOperation, SpecEnumSet, S
 
         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 @@ _C_KW = {
 
     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):
-- 
2.41.0