tools: ynl: add scope qualifier for definitions

Using definitions in kernel policies is awkward right now.
On one hand we want defines for max values and such.
On the other we don't have a way of adding kernel-only defines.
Adding unnecessary defines to uAPI is a bad idea, we won't
be able to delete them. And when it comes to policy user
space should just query it via the policy dump, not use
hard coded defines.

Add a "scope" property to definitions, which will let us tell
the codegen that a definition is for kernel use only. Support
following values:
  - uapi: render into the uAPI header (default, today's behavior)
  - kernel: render to kernel header only
  - user: same as kernel but for the user-side generated header

Definitions may have a header property (definition is "external",
provided by existing header). Extend the scope to headers, too.
If definition has both scope and header properties we will only
generate the includes in the right scope.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20260510192904.3987113-8-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

1 files changed, 29 insertions, 2 deletions

diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index 0e1e486c1185..cdc3646f2642 100755
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -3212,6 +3212,8 @@ def render_uapi(family, cw):
     for const in family['definitions']:
         if const.get('header'):
             continue
+        if const.get('scope', 'uapi') != 'uapi':
+            continue
 
         if const['type'] != 'const':
             cw.writes_defines(defines)
@@ -3339,6 +3341,25 @@ def render_uapi(family, cw):
     cw.p(f'#endif /* {hdr_prot} */')
 
 
+def render_scoped_consts(family, cw, scope):
+    defines = []
+    for const in family['definitions']:
+        if const['type'] != 'const':
+            continue
+        if const.get('header'):
+            continue
+        if const.get('scope') != scope:
+            continue
+        name_pfx = const.get('name-prefix', f"{family.ident_name}-")
+        defines.append([
+            c_upper(family.get('c-define-name',
+                               f"{name_pfx}{const['name']}")),
+            const['value']])
+    if defines:
+        cw.writes_defines(defines)
+        cw.nl()
+
+
 def _render_user_ntf_entry(ri, op):
     if not ri.family.is_classic():
         ri.cw.block_start(line=f"[{op.enum_name}] = ")
@@ -3504,8 +3525,12 @@ def main():
             cw.p('#include "ynl.h"')
         headers = []
     for definition in parsed['definitions'] + parsed['attribute-sets']:
-        if 'header' in definition:
-            headers.append(definition['header'])
+        if 'header' not in definition:
+            continue
+        scope = definition.get('scope', 'uapi')
+        if scope != 'uapi' and scope != args.mode:
+            continue
+        headers.append(definition['header'])
     if args.mode == 'user':
         headers.append(parsed.uapi_header)
     seen_header = []
@@ -3522,6 +3547,7 @@ def main():
             for one in args.user_header:
                 cw.p(f'#include "{one}"')
         else:
+            render_scoped_consts(parsed, cw, 'user')
             cw.p('struct ynl_sock;')
             cw.nl()
             render_user_family(parsed, cw, True)
@@ -3529,6 +3555,7 @@ def main():
 
     if args.mode == "kernel":
         if args.header:
+            render_scoped_consts(parsed, cw, 'kernel')
             for _, struct in sorted(parsed.pure_nested_structs.items()):
                 if struct.request:
                     cw.p('/* Common nested types */')