tools: ynl: make user space policies const

Dan, who's working on C++ YNL, pointed out that the C code
does not make policies const. Sprinkle some 'const's around.
Reported-by: Dan Melnic <dmm@meta.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/net/ynl/lib/ynl-priv.h

@@ -45,17 +45,17 @@ struct ynl_policy_attr {
 	enum ynl_policy_type type;
 	unsigned int len;
 	const char *name;
-	struct ynl_policy_nest *nest;
+	const struct ynl_policy_nest *nest;
 };
 
 struct ynl_policy_nest {
 	unsigned int max_attr;
-	struct ynl_policy_attr *table;
+	const struct ynl_policy_attr *table;
 };
 
 struct ynl_parse_arg {
 	struct ynl_sock *ys;
-	struct ynl_policy_nest *rsp_policy;
+	const struct ynl_policy_nest *rsp_policy;
 	void *data;
 };
 
@@ -119,7 +119,7 @@ struct ynl_dump_state {
 };
 
 struct ynl_ntf_info {
-	struct ynl_policy_nest *policy;
+	const struct ynl_policy_nest *policy;
 	ynl_parse_cb_t cb;
 	size_t alloc_sz;
 	void (*free)(struct ynl_ntf_base_type *ntf);

tools/net/ynl/lib/ynl.c

@@ -46,7 +46,7 @@
 
 /* -- Netlink boiler plate */
 static int
-ynl_err_walk_report_one(struct ynl_policy_nest *policy, unsigned int type,
+ynl_err_walk_report_one(const struct ynl_policy_nest *policy, unsigned int type,
 			char *str, int str_sz, int *n)
 {
 	if (!policy) {
@@ -75,8 +75,8 @@ ynl_err_walk_report_one(struct ynl_policy_nest *policy, unsigned int type,
 
 static int
 ynl_err_walk(struct ynl_sock *ys, void *start, void *end, unsigned int off,
-	     struct ynl_policy_nest *policy, char *str, int str_sz,
-	     struct ynl_policy_nest **nest_pol)
+	     const struct ynl_policy_nest *policy, char *str, int str_sz,
+	     const struct ynl_policy_nest **nest_pol)
 {
 	unsigned int astart_off, aend_off;
 	const struct nlattr *attr;
@@ -206,7 +206,7 @@ ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
 		bad_attr[n] = '\0';
 	}
 	if (tb[NLMSGERR_ATTR_MISS_TYPE]) {
-		struct ynl_policy_nest *nest_pol = NULL;
+		const struct ynl_policy_nest *nest_pol = NULL;
 		unsigned int n, off, type;
 		void *start, *end;
 		int n2;
@@ -296,7 +296,7 @@ static int ynl_cb_done(const struct nlmsghdr *nlh, struct ynl_parse_arg *yarg)
 
 int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr)
 {
-	struct ynl_policy_attr *policy;
+	const struct ynl_policy_attr *policy;
 	unsigned int type, len;
 	unsigned char *data;
 

tools/net/ynl/lib/ynl.h

@@ -76,7 +76,7 @@ struct ynl_sock {
 	struct ynl_ntf_base_type **ntf_last_next;
 
 	struct nlmsghdr *nlh;
-	struct ynl_policy_nest *req_policy;
+	const struct ynl_policy_nest *req_policy;
 	unsigned char *tx_buf;
 	unsigned char *rx_buf;
 	unsigned char raw_buf[];

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

@@ -1507,12 +1507,12 @@ def print_dump_prototype(ri):
 
 
 def put_typol_fwd(cw, struct):
-    cw.p(f'extern struct ynl_policy_nest {struct.render_name}_nest;')
+    cw.p(f'extern const struct ynl_policy_nest {struct.render_name}_nest;')
 
 
 def put_typol(cw, struct):
     type_max = struct.attr_set.max_name
-    cw.block_start(line=f'struct ynl_policy_attr {struct.render_name}_policy[{type_max} + 1] =')
+    cw.block_start(line=f'const struct ynl_policy_attr {struct.render_name}_policy[{type_max} + 1] =')
 
     for _, arg in struct.member_list():
         arg.attr_typol(cw)
@@ -1520,7 +1520,7 @@ def put_typol(cw, struct):
     cw.block_end(line=';')
     cw.nl()
 
-    cw.block_start(line=f'struct ynl_policy_nest {struct.render_name}_nest =')
+    cw.block_start(line=f'const struct ynl_policy_nest {struct.render_name}_nest =')
     cw.p(f'.max_attr = {type_max},')
     cw.p(f'.table = {struct.render_name}_policy,')
     cw.block_end(line=';')