Merge branch 'netlink-specs-add-ynl-spec-for-ovs_flow'

Donald Hunter says:

====================
netlink: specs: add ynl spec for ovs_flow

Add a ynl specification for ovs_flow. The spec is sufficient to dump ovs
flows but some attrs have been left as binary blobs because ynl doesn't
support C arrays in struct definitions yet.

Patches 1-3 add features for genetlink-legacy specs
Patch 4 is the ovs_flow netlink spec
====================

Link: https://lore.kernel.org/r/20230527133107.68161-1-donald.hunter@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/genetlink-legacy.yaml

@@ -124,6 +124,12 @@ properties:
                 $ref: '#/$defs/len-or-define'
               byte-order:
                 enum: [ little-endian, big-endian ]
+              doc:
+                description: Documentation for the struct member attribute.
+                type: string
+              enum:
+                description: Name of the enum type used for the attribute.
+                type: string
         # End genetlink-legacy
 
   attribute-sets:

tools/net/ynl/lib/nlspec.py

@@ -228,11 +228,13 @@ class SpecStructMember(SpecElement):
     Attributes:
         type        string, type of the member attribute
         byte_order  string or None for native byte order
+        enum        string, name of the enum definition
     """
     def __init__(self, family, yaml):
         super().__init__(family, yaml)
         self.type = yaml['type']
         self.byte_order = yaml.get('byte-order')
+        self.enum = yaml.get('enum')
 
 
 class SpecStruct(SpecElement):

tools/net/ynl/lib/ynl.py

@@ -412,7 +412,11 @@ class YnlFamily(SpecFamily):
 
     def _decode_binary(self, attr, attr_spec):
         if attr_spec.struct_name:
-            decoded = attr.as_struct(self.consts[attr_spec.struct_name])
+            members = self.consts[attr_spec.struct_name]
+            decoded = attr.as_struct(members)
+            for m in members:
+                if m.enum:
+                    self._decode_enum(decoded, m)
         elif attr_spec.sub_type:
             decoded = attr.as_c_array(attr_spec.sub_type)
         else:
@@ -541,7 +545,7 @@ class YnlFamily(SpecFamily):
         if op.fixed_header:
             fixed_header_members = self.consts[op.fixed_header].members
             for m in fixed_header_members:
-                value = vals.pop(m.name)
+                value = vals.pop(m.name) if m.name in vals else 0
                 format = NlAttr.get_format(m.type, m.byte_order)
                 msg += format.pack(value)
         for name, value in vals.items():