netlink: specs: support generating code for genl socket priv

The family struct is auto-generated for new families, support
use of the sock_priv_* mechanism added in commit a731132424ad
("genetlink: introduce per-sock family private storage").

For example if the family wants to use struct sk_buff as its
private struct (unrealistic but just for illustration), it would
add to its spec:

  kernel-family:
    headers: [ "linux/skbuff.h" ]
    sock-priv: struct sk_buff

ynl-gen-c will declare the appropriate priv size and hook
in function prototypes to be implemented by the family.

Link: https://lore.kernel.org/r/20240308190319.2523704-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 12 insertions, 0 deletions

diff --git a/tools/net/ynl/lib/nlspec.py b/tools/net/ynl/lib/nlspec.py
index fbce52395b3b31..6d08ab9e213fbf 100644
--- a/tools/net/ynl/lib/nlspec.py
+++ b/tools/net/ynl/lib/nlspec.py
@@ -418,6 +418,7 @@ class SpecFamily(SpecElement):
         consts     dict of all constants/enums
         fixed_header  string, optional name of family default fixed header struct
         mcast_groups  dict of all multicast groups (index by name)
+        kernel_family   dict of kernel family attributes
     """
     def __init__(self, spec_path, schema_path=None, exclude_ops=None):
         with open(spec_path, "r") as stream:
@@ -461,6 +462,7 @@ class SpecFamily(SpecElement):
         self.ntfs = collections.OrderedDict()
         self.consts = collections.OrderedDict()
         self.mcast_groups = collections.OrderedDict()
+        self.kernel_family = collections.OrderedDict(self.yaml.get('kernel-family', {}))
 
         last_exception = None
         while len(self._resolution_list) > 0:
diff --git a/tools/net/ynl/ynl-gen-c.py b/tools/net/ynl/ynl-gen-c.py
index 5bb7ca01fe510d..6b7eb2d2aaf188 100755
--- a/tools/net/ynl/ynl-gen-c.py
+++ b/tools/net/ynl/ynl-gen-c.py
@@ -2342,6 +2342,10 @@ def print_kernel_family_struct_hdr(family, cw):
 
     cw.p(f"extern struct genl_family {family.c_name}_nl_family;")
     cw.nl()
+    if 'sock-priv' in family.kernel_family:
+        cw.p(f'void {family.c_name}_nl_sock_priv_init({family.kernel_family["sock-priv"]} *priv);')
+        cw.p(f'void {family.c_name}_nl_sock_priv_destroy({family.kernel_family["sock-priv"]} *priv);')
+        cw.nl()
 
 
 def print_kernel_family_struct_src(family, cw):
@@ -2363,6 +2367,11 @@ def print_kernel_family_struct_src(family, cw):
     if family.mcgrps['list']:
         cw.p(f'.mcgrps\t\t= {family.c_name}_nl_mcgrps,')
         cw.p(f'.n_mcgrps\t= ARRAY_SIZE({family.c_name}_nl_mcgrps),')
+    if 'sock-priv' in family.kernel_family:
+        cw.p(f'.sock_priv_size\t= sizeof({family.kernel_family["sock-priv"]}),')
+        # Force cast here, actual helpers take pointer to the real type.
+        cw.p(f'.sock_priv_init\t= (void *){family.c_name}_nl_sock_priv_init,')
+        cw.p(f'.sock_priv_destroy = (void *){family.c_name}_nl_sock_priv_destroy,')
     cw.block_end(';')
 
 
@@ -2659,6 +2668,7 @@ def main():
                 cw.p(f'#include "{os.path.basename(args.out_file[:-2])}.h"')
             cw.nl()
         headers = ['uapi/' + parsed.uapi_header]
+        headers += parsed.kernel_family.get('headers', [])
     else:
         cw.p('#include <stdlib.h>')
         cw.p('#include <string.h>')