[PATCH RFC bpf-next 1/3] libbpf: Add new bpf_object__load2() using new-style opts

["Toke Høiland-Jørgensen" <toke@redhat.com>]

From: Toke Høiland-Jørgensen <toke@redhat.com>

Since we introduced DECLARE_LIBBPF_OPTS and related macros for declaring
function options, that is now the preferred way to extend APIs. Introduce a
variant of the bpf_object__load() function that uses this function, and
deprecate the _xattr variant. Since all the good function names were taken,
the new function is unimaginatively called bpf_object__load2().

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 tools/lib/bpf/libbpf.c   |   31 ++++++++++++++++++-------------
 tools/lib/bpf/libbpf.h   |   13 +++++++++++++
 tools/lib/bpf/libbpf.map |    1 +
 3 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index febbaac3daf4..266b725e444b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4844,15 +4844,12 @@ static int bpf_object__resolve_externs(struct bpf_object *obj,
 	return 0;
 }
 
-int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
+int bpf_object__load2(struct bpf_object *obj,
+		      const struct bpf_object_load_opts *opts)
 {
-	struct bpf_object *obj;
 	int err, i;
 
-	if (!attr)
-		return -EINVAL;
-	obj = attr->obj;
-	if (!obj)
+	if (!obj || !OPTS_VALID(opts, bpf_object_load_opts))
 		return -EINVAL;
 
 	if (obj->loaded) {
@@ -4867,8 +4864,10 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 	err = err ? : bpf_object__sanitize_and_load_btf(obj);
 	err = err ? : bpf_object__sanitize_maps(obj);
 	err = err ? : bpf_object__create_maps(obj);
-	err = err ? : bpf_object__relocate(obj, attr->target_btf_path);
-	err = err ? : bpf_object__load_progs(obj, attr->log_level);
+	err = err ? : bpf_object__relocate(obj,
+					   OPTS_GET(opts, target_btf_path, NULL));
+	err = err ? : bpf_object__load_progs(obj,
+					     OPTS_GET(opts, log_level, 0));
 	if (err)
 		goto out;
 
@@ -4884,13 +4883,19 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 	return err;
 }
 
-int bpf_object__load(struct bpf_object *obj)
+int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
 {
-	struct bpf_object_load_attr attr = {
-		.obj = obj,
-	};
+	DECLARE_LIBBPF_OPTS(bpf_object_load_opts, opts,
+	    .log_level = attr->log_level,
+	    .target_btf_path = attr->target_btf_path,
+	);
+
+	return bpf_object__load2(attr->obj, &opts);
+}
 
-	return bpf_object__load_xattr(&attr);
+int bpf_object__load(struct bpf_object *obj)
+{
+	return bpf_object__load2(obj, NULL);
 }
 
 static int make_parent_dir(const char *path)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index fe592ef48f1b..ce86277d7445 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -132,8 +132,21 @@ struct bpf_object_load_attr {
 	const char *target_btf_path;
 };
 
+struct bpf_object_load_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* log level on load */
+	int log_level;
+	/* BTF path (for CO-RE relocations) */
+	const char *target_btf_path;
+};
+#define bpf_object_load_opts__last_field target_btf_path
+
 /* Load/unload object into/from kernel */
 LIBBPF_API int bpf_object__load(struct bpf_object *obj);
+LIBBPF_API int bpf_object__load2(struct bpf_object *obj,
+				 const struct bpf_object_load_opts *opts);
+/* deprecated, use bpf_object__load2() instead */
 LIBBPF_API int bpf_object__load_xattr(struct bpf_object_load_attr *attr);
 LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
 
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index e3a471f38a71..d6cb860763d1 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -217,6 +217,7 @@ LIBBPF_0.0.7 {
 		bpf_object__attach_skeleton;
 		bpf_object__destroy_skeleton;
 		bpf_object__detach_skeleton;
+		bpf_object__load2;
 		bpf_object__load_skeleton;
 		bpf_object__open_skeleton;
 		bpf_program__attach;