ynl: rename array-nest to indexed-array

Some implementations, like bonding, has nest array with same attr type.
To support all kinds of entries under one nest array. As discussed[1],
let's rename array-nest to indexed-array, and assuming the value is
a nest by passing the type via sub-type.

[1] https://lore.kernel.org/netdev/20240312100105.16a59086@kernel.org/

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20240404063114.1221532-2-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/genetlink-c.yaml

@@ -158,7 +158,7 @@ properties:
               type: &attr-type
                 enum: [ unused, pad, flag, binary,
                         uint, sint, u8, u16, u32, u64, s32, s64,
-                        string, nest, array-nest, nest-type-value ]
+                        string, nest, indexed-array, nest-type-value ]
               doc:
                 description: Documentation of the attribute.
                 type: string

Documentation/netlink/genetlink-legacy.yaml

@@ -201,7 +201,7 @@ properties:
                 description: The netlink attribute type
                 enum: [ unused, pad, flag, binary, bitfield32,
                         uint, sint, u8, u16, u32, u64, s32, s64,
-                        string, nest, array-nest, nest-type-value ]
+                        string, nest, indexed-array, nest-type-value ]
               doc:
                 description: Documentation of the attribute.
                 type: string

Documentation/netlink/genetlink.yaml

@@ -124,7 +124,7 @@ properties:
               type: &attr-type
                 enum: [ unused, pad, flag, binary,
                         uint, sint, u8, u16, u32, u64, s32, s64,
-                        string, nest, array-nest, nest-type-value ]
+                        string, nest, indexed-array, nest-type-value ]
               doc:
                 description: Documentation of the attribute.
                 type: string

Documentation/netlink/netlink-raw.yaml

@@ -222,7 +222,7 @@ properties:
                 description: The netlink attribute type
                 enum: [ unused, pad, flag, binary, bitfield32,
                         u8, u16, u32, u64, s8, s16, s32, s64,
-                        string, nest, array-nest, nest-type-value,
+                        string, nest, indexed-array, nest-type-value,
                         sub-message ]
               doc:
                 description: Documentation of the attribute.

Documentation/netlink/specs/nlctrl.yaml

@@ -65,11 +65,13 @@ attribute-sets:
         type: u32
       -
         name: ops
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: op-attrs
       -
         name: mcast-groups
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: mcast-group-attrs
       -
         name: policy

Documentation/netlink/specs/rt_link.yaml

@@ -1690,7 +1690,8 @@ attribute-sets:
         type: binary
       -
         name: hw-s-info
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: hw-s-info-one
       -
         name: l3-stats

Documentation/netlink/specs/tc.yaml

@@ -1988,7 +1988,8 @@ attribute-sets:
         nested-attributes: tc-ematch-attrs
       -
         name: act
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-act-attrs
       -
         name: police
@@ -2128,7 +2129,8 @@ attribute-sets:
         type: u32
       -
         name: tin-stats
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-cake-tin-stats-attrs
       -
         name: deficit
@@ -2348,7 +2350,8 @@ attribute-sets:
         type: string
       -
         name: act
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-act-attrs
       -
         name: key-eth-dst
@@ -2849,7 +2852,8 @@ attribute-sets:
         type: string
       -
         name: act
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-act-attrs
       -
         name: mask
@@ -3002,7 +3006,8 @@ attribute-sets:
         type: u32
       -
         name: act
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-act-attrs
       -
         name: flags
@@ -3375,7 +3380,8 @@ attribute-sets:
         nested-attributes: tc-police-attrs
       -
         name: act
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-act-attrs
   -
     name: tc-taprio-attrs
@@ -3593,7 +3599,8 @@ attribute-sets:
         nested-attributes: tc-police-attrs
       -
         name: act
-        type: array-nest
+        type: indexed-array
+        sub-type: nest
         nested-attributes: tc-act-attrs
       -
         name: indev

Documentation/userspace-api/netlink/genetlink-legacy.rst

@@ -46,10 +46,16 @@ For reference the ``multi-attr`` array may look like this::
 
 where ``ARRAY-ATTR`` is the array entry type.
 
-array-nest
+indexed-array
-~~~~~~~~~~
+~~~~~~~~~~~~~
 
-``array-nest`` creates the following structure::
+``indexed-array`` wraps the entire array in an extra attribute (hence
+limiting its size to 64kB). The ``ENTRY`` nests are special and have the
+index of the entry as their type instead of normal attribute type.
+
+A ``sub-type`` is needed to describe what type in the ``ENTRY``. A ``nest``
+``sub-type`` means there are nest arrays in the ``ENTRY``, with the structure
+looks like::
 
   [SOME-OTHER-ATTR]
   [ARRAY-ATTR]

tools/net/ynl/lib/ynl.py

@@ -631,15 +631,18 @@ class YnlFamily(SpecFamily):
                 decoded = self._formatted_string(decoded, attr_spec.display_hint)
         return decoded
 
-    def _decode_array_nest(self, attr, attr_spec):
+    def _decode_array_attr(self, attr, attr_spec):
         decoded = []
         offset = 0
         while offset < len(attr.raw):
             item = NlAttr(attr.raw, offset)
             offset += item.full_len
 
-            subattrs = self._decode(NlAttrs(item.raw), attr_spec['nested-attributes'])
+            if attr_spec["sub-type"] == 'nest':
-            decoded.append({ item.type: subattrs })
+                subattrs = self._decode(NlAttrs(item.raw), attr_spec['nested-attributes'])
+                decoded.append({ item.type: subattrs })
+            else:
+                raise Exception(f'Unknown {attr_spec["sub-type"]} with name {attr_spec["name"]}')
         return decoded
 
     def _decode_nest_type_value(self, attr, attr_spec):
@@ -733,8 +736,8 @@ class YnlFamily(SpecFamily):
                 decoded = attr.as_scalar(attr_spec['type'], attr_spec.byte_order)
                 if 'enum' in attr_spec:
                     decoded = self._decode_enum(decoded, attr_spec)
-            elif attr_spec["type"] == 'array-nest':
+            elif attr_spec["type"] == 'indexed-array':
-                decoded = self._decode_array_nest(attr, attr_spec)
+                decoded = self._decode_array_attr(attr, attr_spec)
             elif attr_spec["type"] == 'bitfield32':
                 value, selector = struct.unpack("II", attr.raw)
                 if 'enum' in attr_spec:

tools/net/ynl/ynl-gen-c.py

@@ -841,8 +841,11 @@ class AttrSet(SpecAttrSet):
             t = TypeBitfield32(self.family, self, elem, value)
         elif elem['type'] == 'nest':
             t = TypeNest(self.family, self, elem, value)
-        elif elem['type'] == 'array-nest':
+        elif elem['type'] == 'indexed-array' and 'sub-type' in elem:
-            t = TypeArrayNest(self.family, self, elem, value)
+            if elem["sub-type"] == 'nest':
+                t = TypeArrayNest(self.family, self, elem, value)
+            else:
+                raise Exception(f'new_attr: unsupported sub-type {elem["sub-type"]}')
         elif elem['type'] == 'nest-type-value':
             t = TypeNestTypeValue(self.family, self, elem, value)
         else:
@@ -1055,7 +1058,7 @@ class Family(SpecFamily):
                     if nested in self.root_sets:
                         raise Exception("Inheriting members to a space used as root not supported")
                     inherit.update(set(spec['type-value']))
-                elif spec['type'] == 'array-nest':
+                elif spec['type'] == 'indexed-array':
                     inherit.add('idx')
                 self.pure_nested_structs[nested].set_inherited(inherit)
 
@@ -1619,9 +1622,12 @@ def _multi_parse(ri, struct, init_lines, local_vars):
     multi_attrs = set()
     needs_parg = False
     for arg, aspec in struct.member_list():
-        if aspec['type'] == 'array-nest':
+        if aspec['type'] == 'indexed-array' and 'sub-type' in aspec:
-            local_vars.append(f'const struct nlattr *attr_{aspec.c_name};')
+            if aspec["sub-type"] == 'nest':
-            array_nests.add(arg)
+                local_vars.append(f'const struct nlattr *attr_{aspec.c_name};')
+                array_nests.add(arg)
+            else:
+                raise Exception(f'Not supported sub-type {aspec["sub-type"]}')
         if 'multi-attr' in aspec:
             multi_attrs.add(arg)
         needs_parg |= 'nested-attributes' in aspec