tools: ynl: don't use genlmsghdr in classic netlink

Make sure the codegen calls the right YNL lib helper to start
the request based on family type. Classic netlink request must
not include the genl header.

Conversely don't expect genl headers in the responses.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://patch.msgid.link/20250410014658.782120-10-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 22 insertions, 8 deletions

diff --git a/tools/net/ynl/lib/ynl-priv.h b/tools/net/ynl/lib/ynl-priv.h
index 3c09a7bbfba5..634eb16548b9 100644
--- a/tools/net/ynl/lib/ynl-priv.h
+++ b/tools/net/ynl/lib/ynl-priv.h
@@ -94,6 +94,9 @@ struct ynl_ntf_base_type {
 	unsigned char data[] __attribute__((aligned(8)));
 };
 
+struct nlmsghdr *ynl_msg_start_req(struct ynl_sock *ys, __u32 id);
+struct nlmsghdr *ynl_msg_start_dump(struct ynl_sock *ys, __u32 id);
+
 struct nlmsghdr *
 ynl_gemsg_start_req(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version);
 struct nlmsghdr *
diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c
index b9fda1a99453..70f899a54007 100644
--- a/tools/net/ynl/lib/ynl.c
+++ b/tools/net/ynl/lib/ynl.c
@@ -451,14 +451,14 @@ ynl_gemsg_start(struct ynl_sock *ys, __u32 id, __u16 flags,
 	return nlh;
 }
 
-void ynl_msg_start_req(struct ynl_sock *ys, __u32 id)
+struct nlmsghdr *ynl_msg_start_req(struct ynl_sock *ys, __u32 id)
 {
-	ynl_msg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK);
+	return ynl_msg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK);
 }
 
-void ynl_msg_start_dump(struct ynl_sock *ys, __u32 id)
+struct nlmsghdr *ynl_msg_start_dump(struct ynl_sock *ys, __u32 id)
 {
-	ynl_msg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP);
+	return ynl_msg_start(ys, id, NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP);
 }
 
 struct nlmsghdr *
diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index 04f1ac62cb01..b0b47a493a86 100755
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -1710,7 +1710,10 @@ def _multi_parse(ri, struct, init_lines, local_vars):
         ri.cw.p(f'dst->{arg} = {arg};')
 
     if ri.fixed_hdr:
-        ri.cw.p('hdr = ynl_nlmsg_data_offset(nlh, sizeof(struct genlmsghdr));')
+        if ri.family.is_classic():
+            ri.cw.p('hdr = ynl_nlmsg_data(nlh);')
+        else:
+            ri.cw.p('hdr = ynl_nlmsg_data_offset(nlh, sizeof(struct genlmsghdr));')
         ri.cw.p(f"memcpy(&dst->_hdr, hdr, sizeof({ri.fixed_hdr}));")
     for anest in sorted(all_multi):
         aspec = struct[anest]
@@ -1857,7 +1860,10 @@ def print_req(ri):
     ri.cw.block_start()
     ri.cw.write_func_lvar(local_vars)
 
-    ri.cw.p(f"nlh = ynl_gemsg_start_req(ys, {ri.nl.get_family_id()}, {ri.op.enum_name}, 1);")
+    if ri.family.is_classic():
+        ri.cw.p(f"nlh = ynl_msg_start_req(ys, {ri.op.enum_name});")
+    else:
+        ri.cw.p(f"nlh = ynl_gemsg_start_req(ys, {ri.nl.get_family_id()}, {ri.op.enum_name}, 1);")
 
     ri.cw.p(f"ys->req_policy = &{ri.struct['request'].render_name}_nest;")
     if 'reply' in ri.op[ri.op_mode]:
@@ -1926,7 +1932,10 @@ def print_dump(ri):
     else:
         ri.cw.p(f'yds.rsp_cmd = {ri.op.rsp_value};')
     ri.cw.nl()
-    ri.cw.p(f"nlh = ynl_gemsg_start_dump(ys, {ri.nl.get_family_id()}, {ri.op.enum_name}, 1);")
+    if ri.family.is_classic():
+        ri.cw.p(f"nlh = ynl_msg_start_dump(ys, {ri.op.enum_name});")
+    else:
+        ri.cw.p(f"nlh = ynl_gemsg_start_dump(ys, {ri.nl.get_family_id()}, {ri.op.enum_name}, 1);")
 
     if ri.fixed_hdr:
         ri.cw.p("hdr_len = sizeof(req->_hdr);")
@@ -2736,7 +2745,9 @@ def render_user_family(family, cw, prototype):
     if family.is_classic():
         cw.p(f'.is_classic\t= true,')
         cw.p(f'.classic_id\t= {family.get("protonum")},')
-    if family.fixed_header:
+    if family.is_classic():
+        cw.p(f'.hdr_len\t= sizeof(struct {c_lower(family.fixed_header)}),')
+    elif family.fixed_header:
         cw.p(f'.hdr_len\t= sizeof(struct genlmsghdr) + sizeof(struct {c_lower(family.fixed_header)}),')
     else:
         cw.p('.hdr_len\t= sizeof(struct genlmsghdr),')