Hristo Venev [off-list ref] writes:

This patch adds an initial YNL specification for NBD. The specification
can be used to produce a UAPI header that is equivalent to the one
currently shipped in the kernel.

The spec appears to be accurate enough so that commands can be issued
with pyynl.

Signed-off-by: Hristo Venev <redacted>
---
 Documentation/netlink/specs/nbd.yaml | 206 +++++++++++++++++++++++++++
 1 file changed, 206 insertions(+)
 create mode 100644 Documentation/netlink/specs/nbd.yaml

There are yamllint errors:

make -C tools/net/ynl lint
make: Entering directory '/home/donaldh/net-next/tools/net/ynl'
yamllint ../../../Documentation/netlink/specs
../../../Documentation/netlink/specs/nbd.yaml
  159:81    error    line too long (104 > 80 characters)  (line-length)
  169:6     error    syntax error: expected <block end>, but found '<block mapping start>' (syntax)
  170:7     error    wrong indentation: expected 5 but found 6  (indentation)

Prefer to see a meaningful doc string here.

+
+c-family-name: nbd-genl-family-name
+c-version-name: nbd-genl-version
+max-by-define: true
+
+attribute-sets:
+  -
+    name: nbd-attrs
+    name-prefix: nbd-attr-
+    doc: Configuration policy attributes, used for CONNECT
+    attributes:
+      -
+        name: unspec
+        value: 0
+        type: unused

No need for unspec in the attribute list, ynl codegen does the right thing.

+      -
+        name: index
+        type: u32
+      -
+        name: size-bytes
+        type: u64
+      -
+        name: block-size-bytes
+        type: u64
+      -
+        name: timeout
+        type: u64
+      -
+        name: server-flags
+        type: u64
+      -
+        name: client-flags
+        type: u64
+      -
+        name: sockets
+        type: nest
+        nested-attributes: sock-item-attrs
+      -
+        name: dead-conn-timeout
+        type: u64
+      -
+        name: device-list
+        type: nest
+        nested-attributes: device-item-attrs
+      -
+        name: backend-identifier
+        type: string
+  -
+    name: device-item-attrs
+    name-prefix: nbd-device-item-
+    doc: |
+      This is the format for multiple devices with :code:`NBD_ATTR_DEVICE_LIST`
+
+      .. code-block::
+
+        [NBD_ATTR_DEVICE_LIST]
+          [NBD_DEVICE_ITEM]
+            [NBD_DEVICE_INDEX]
+            [NBD_DEVICE_CONNECTED]
+    attributes:
+      -
+        name: unspec
+        value: 0
+        type: unused

Not required.

+      -
+        name: item
+        name-prefix: nbd-device-
+        type: nest
+        nested-attributes: device-attrs
+        multi-attr: true
+  -
+    name: device-attrs
+    name-prefix: nbd-device-
+    attr-max-name: nbd-device-attr-max
+    attributes:
+      -
+        name: unspec
+        value: 0
+        type: unused

Not required.

+      -
+        name: index
+        type: u32
+      -
+        name: connected
+        type: u8
+  -
+    name: sock-item-attrs
+    name-prefix: nbd-sock-item-
+    doc: |
+      This is the format for multiple sockets with :code:`NBD_ATTR_SOCKETS`
+
+      .. code-block::
+
+        [NBD_ATTR_SOCKETS]
+          [NBD_SOCK_ITEM]
+            [NBD_SOCK_FD]
+          [NBD_SOCK_ITEM]
+            [NBD_SOCK_FD]
+    attributes:
+      -
+        name: unspec
+        value: 0
+        type: unused

Not required.

+      -
+        name: item
+        name-prefix: nbd-sock-
+        type: nest
+        nested-attributes: sock-attrs
+        multi-attr: true
+  -
+    name: sock-attrs
+    name-prefix: nbd-sock-
+    attributes:
+      -
+        name: unspec
+        value: 0
+        type: unused

Not required.

+      -
+        name: fd
+        type: u32
+
+operations:
+  enum-model: unified
+  name-prefix: nbd-cmd-
+  list:
+    -
+      name: unspec
+      value: 0
+      doc: NBD_CMD_UNSPEC

Not required.

+    -
+      name: connect
+      doc: See :file:`drivers/block/nbd.c`, :code:`nbd_genl_connect()`

Prefer to see meaningful doc string (same for other ops)

+      attribute-set: nbd-attrs
+      dont-validate: [strict]

nbd.c has strict & dump, should this be [strict, dump] ? (same for other ops)

+      do:
+        request:
+          attributes:
+            - index
+            - size-bytes
+            - block-size-bytes
+            - timeout
+            - server-flags
+            - client-flags
+            - sockets
+            - dead-conn-timeout
+            - backend-identifier
+        reply:
+          attributes:
+            - index
+    -
+      name: disconnect
+      doc: See :file:`drivers/block/nbd.c`, :code:`nbd_genl_disconnect()`
+      attribute-set: nbd-attrs
+      dont-validate: [strict]
+      do:
+        request:
+          attributes:
+            - index
+    -
+      name: reconfigure
+      doc: See :file:`drivers/block/nbd.c`, :code:`nbd_genl_reconfigure()`
+      attribute-set: nbd-attrs
+      dont-validate: [strict]
+      do:
+        request:
+          attributes:
+            - index
+            - size-bytes
+            - block-size-bytes
+            - timeout
+            - client-flags
+            - sockets
+            - dead-conn-timeout
+            - backend-identifier
+    -
+      name: link-dead
+      doc: See :file:`drivers/block/nbd.c`, :code:`nbd_mark_nsock_dead()` / :code:`nbd_dead_link_work()`
+      attribute-set: nbd-attrs
+      event:
+        attributes:
+          - index
+      mcgrp: nbd_mc_group
+    -
+      name: status
+      doc: See :file:`drivers/block/nbd.c`, :code:`nbd_genl_status()`
+      attribute-set: nbd-attrs
+      dont-validate: [strict]
+      do:
+        request:
+          attributes:
+            - index
+        reply:
+          attributes:
+            - device-list
+
+mcast-groups:
+  list:
+    -
+      name: nbd_mc_group
+      c-define-name: nbd-genl-mcast-group-name