bpf: refactory struct_ops type initialization to a function.

Move the majority of the code to bpf_struct_ops_init_one(), which can then
be utilized for the initialization of newly registered dynamically
allocated struct_ops types in the following patches.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-2-thinker.li@gmail.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

include/linux/btf.h

@@ -137,6 +137,7 @@ struct btf_struct_metas {
 
 extern const struct file_operations btf_fops;
 
+const char *btf_get_name(const struct btf *btf);
 void btf_get(struct btf *btf);
 void btf_put(struct btf *btf);
 int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_sz);

kernel/bpf/bpf_struct_ops.c

@@ -110,62 +110,48 @@ const struct bpf_prog_ops bpf_struct_ops_prog_ops = {
 
 static const struct btf_type *module_type;
 
-void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
+static void bpf_struct_ops_init_one(struct bpf_struct_ops *st_ops,
+				    struct btf *btf,
+				    struct bpf_verifier_log *log)
 {
-	s32 type_id, value_id, module_id;
 	const struct btf_member *member;
-	struct bpf_struct_ops *st_ops;
 	const struct btf_type *t;
+	s32 type_id, value_id;
 	char value_name[128];
 	const char *mname;
-	u32 i, j;
-
-	/* Ensure BTF type is emitted for "struct bpf_struct_ops_##_name" */
-#define BPF_STRUCT_OPS_TYPE(_name) BTF_TYPE_EMIT(struct bpf_struct_ops_##_name);
-#include "bpf_struct_ops_types.h"
-#undef BPF_STRUCT_OPS_TYPE
-
-	module_id = btf_find_by_name_kind(btf, "module", BTF_KIND_STRUCT);
-	if (module_id < 0) {
-		pr_warn("Cannot find struct module in btf_vmlinux\n");
-		return;
-	}
-	module_type = btf_type_by_id(btf, module_id);
-
-	for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
-		st_ops = bpf_struct_ops[i];
+	int i;
 
 	if (strlen(st_ops->name) + VALUE_PREFIX_LEN >=
 	    sizeof(value_name)) {
 		pr_warn("struct_ops name %s is too long\n",
 			st_ops->name);
-			continue;
+		return;
 	}
 	sprintf(value_name, "%s%s", VALUE_PREFIX, st_ops->name);
 
 	value_id = btf_find_by_name_kind(btf, value_name,
 					 BTF_KIND_STRUCT);
 	if (value_id < 0) {
-			pr_warn("Cannot find struct %s in btf_vmlinux\n",
-				value_name);
-			continue;
+		pr_warn("Cannot find struct %s in %s\n",
+			value_name, btf_get_name(btf));
+		return;
 	}
 
 	type_id = btf_find_by_name_kind(btf, st_ops->name,
 					BTF_KIND_STRUCT);
 	if (type_id < 0) {
-			pr_warn("Cannot find struct %s in btf_vmlinux\n",
-				st_ops->name);
-			continue;
+		pr_warn("Cannot find struct %s in %s\n",
+			st_ops->name, btf_get_name(btf));
+		return;
 	}
 	t = btf_type_by_id(btf, type_id);
 	if (btf_type_vlen(t) > BPF_STRUCT_OPS_MAX_NR_MEMBERS) {
 		pr_warn("Cannot support #%u members in struct %s\n",
 			btf_type_vlen(t), st_ops->name);
-			continue;
+		return;
 	}
 
-		for_each_member(j, t, member) {
+	for_each_member(i, t, member) {
 		const struct btf_type *func_proto;
 
 		mname = btf_name_by_offset(btf, member->name_off);
@@ -187,14 +173,14 @@ void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
 		if (func_proto &&
 		    btf_distill_func_proto(log, btf,
 					   func_proto, mname,
-						   &st_ops->func_models[j])) {
+					   &st_ops->func_models[i])) {
 			pr_warn("Error in parsing func ptr %s in struct %s\n",
 				mname, st_ops->name);
 			break;
 		}
 	}
 
-		if (j == btf_type_vlen(t)) {
+	if (i == btf_type_vlen(t)) {
 		if (st_ops->init(btf)) {
 			pr_warn("Error in init bpf_struct_ops %s\n",
 				st_ops->name);
@@ -206,6 +192,29 @@ void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
 							    value_id);
 		}
 	}
+}
+
+void bpf_struct_ops_init(struct btf *btf, struct bpf_verifier_log *log)
+{
+	struct bpf_struct_ops *st_ops;
+	s32 module_id;
+	u32 i;
+
+	/* Ensure BTF type is emitted for "struct bpf_struct_ops_##_name" */
+#define BPF_STRUCT_OPS_TYPE(_name) BTF_TYPE_EMIT(struct bpf_struct_ops_##_name);
+#include "bpf_struct_ops_types.h"
+#undef BPF_STRUCT_OPS_TYPE
+
+	module_id = btf_find_by_name_kind(btf, "module", BTF_KIND_STRUCT);
+	if (module_id < 0) {
+		pr_warn("Cannot find struct module in %s\n", btf_get_name(btf));
+		return;
+	}
+	module_type = btf_type_by_id(btf, module_id);
+
+	for (i = 0; i < ARRAY_SIZE(bpf_struct_ops); i++) {
+		st_ops = bpf_struct_ops[i];
+		bpf_struct_ops_init_one(st_ops, btf, log);
 	}
 }
 

kernel/bpf/btf.c

@@ -1707,6 +1707,11 @@ static void btf_free_rcu(struct rcu_head *rcu)
 	btf_free(btf);
 }
 
+const char *btf_get_name(const struct btf *btf)
+{
+	return btf->name;
+}
+
 void btf_get(struct btf *btf)
 {
 	refcount_inc(&btf->refcnt);