libbpf: Streamline error reporting for high-level APIs

Implement changes to error reporting for high-level libbpf APIs to make them
less surprising and less error-prone to users:
- in all the cases when error happens, errno is set to an appropriate error
value;
- in libbpf 1.0 mode, all pointer-returning APIs return NULL on error and
error code is communicated through errno; this applies both to APIs that
already returned NULL before (so now they communicate more detailed error
codes), as well as for many APIs that used ERR_PTR() macro and encoded
error numbers as fake pointers.
- in legacy (default) mode, those APIs that were returning ERR_PTR(err),
continue doing so, but still set errno.

With these changes, errno can be always used to extract actual error,
regardless of legacy or libbpf 1.0 modes. This is utilized internally in
libbpf in places where libbpf uses it's own high-level APIs.
libbpf_get_error() is adapted to handle both cases completely transparently to
end-users (and is used by libbpf consistently as well).

More context, justification, and discussion can be found in "Libbpf: the road
to v1.0" document ([0]).

[0] https://docs.google.com/document/d/1UyjTZuPFWiPFyKk1tV5an11_iaRuec6U-ZESZ54nNTY

Signed-off-by: Andrii Nakryiko <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Acked-by: John Fastabend <[e-mail]>
Acked-by: Toke Høiland-Jørgensen <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/lib/bpf/bpf_prog_linfo.c

···
 	nr_linfo = info->nr_line_info;
 
 	if (!nr_linfo)
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	/*
 	 * The min size that bpf_prog_linfo has to access for
···
 	 */
 	if (info->line_info_rec_size <
 	    offsetof(struct bpf_line_info, file_name_off))
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	prog_linfo = calloc(1, sizeof(*prog_linfo));
 	if (!prog_linfo)
-		return NULL;
+		return errno = ENOMEM, NULL;
 
 	/* Copy xlated line_info */
 	prog_linfo->nr_linfo = nr_linfo;
···
 
 err_free:
 	bpf_prog_linfo__free(prog_linfo);
-	return NULL;
+	return errno = EINVAL, NULL;
 }
 
 const struct bpf_line_info *
···
 	const __u64 *jited_linfo;
 
 	if (func_idx >= prog_linfo->nr_jited_func)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	nr_linfo = prog_linfo->nr_jited_linfo_per_func[func_idx];
 	if (nr_skip >= nr_linfo)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	start = prog_linfo->jited_linfo_func_idx[func_idx] + nr_skip;
 	jited_rec_size = prog_linfo->jited_rec_size;
···
 		(start * jited_rec_size);
 	jited_linfo = raw_jited_linfo;
 	if (addr < *jited_linfo)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	nr_linfo -= nr_skip;
 	rec_size = prog_linfo->rec_size;
···
 
 	nr_linfo = prog_linfo->nr_linfo;
 	if (nr_skip >= nr_linfo)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	rec_size = prog_linfo->rec_size;
 	raw_linfo = prog_linfo->raw_linfo + (nr_skip * rec_size);
 	linfo = raw_linfo;
 	if (insn_off < linfo->insn_off)
-		return NULL;
+		return errno = ENOENT, NULL;
 
 	nr_linfo -= nr_skip;
 	for (i = 0; i < nr_linfo; i++) {

tools/lib/bpf/btf.c

···
 const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
 {
 	if (type_id >= btf->start_id + btf->nr_types)
-		return NULL;
+		return errno = EINVAL, NULL;
 	return btf_type_by_id((struct btf *)btf, type_id);
 }
 
···
 int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
 {
 	if (ptr_sz != 4 && ptr_sz != 8)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	btf->ptr_sz = ptr_sz;
 	return 0;
 }
···
 int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
 {
 	if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
 	if (!btf->swapped_endian) {
···
 	int i;
 
 	t = btf__type_by_id(btf, type_id);
-	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
-	     i++) {
+	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) {
 		switch (btf_kind(t)) {
 		case BTF_KIND_INT:
 		case BTF_KIND_STRUCT:
···
 		case BTF_KIND_ARRAY:
 			array = btf_array(t);
 			if (nelems && array->nelems > UINT32_MAX / nelems)
-				return -E2BIG;
+				return libbpf_err(-E2BIG);
 			nelems *= array->nelems;
 			type_id = array->type;
 			break;
 		default:
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		}
 
 		t = btf__type_by_id(btf, type_id);
···
 
 done:
 	if (size < 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (nelems && size > UINT32_MAX / nelems)
-		return -E2BIG;
+		return libbpf_err(-E2BIG);
 
 	return nelems * size;
 }
···
 		for (i = 0; i < vlen; i++, m++) {
 			align = btf__align_of(btf, m->type);
 			if (align <= 0)
-				return align;
+				return libbpf_err(align);
 			max_align = max(max_align, align);
 		}
 
···
 	}
 	default:
 		pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
-		return 0;
+		return errno = EINVAL, 0;
 	}
 }
 
···
 	}
 
 	if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	return type_id;
 }
···
 			return i;
 	}
 
-	return -ENOENT;
+	return libbpf_err(-ENOENT);
 }
 
 __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
···
 			return i;
 	}
 
-	return -ENOENT;
+	return libbpf_err(-ENOENT);
 }
 
 static bool btf_is_modifiable(const struct btf *btf)
···
 
 struct btf *btf__new_empty(void)
 {
-	return btf_new_empty(NULL);
+	return libbpf_ptr(btf_new_empty(NULL));
 }
 
 struct btf *btf__new_empty_split(struct btf *base_btf)
 {
-	return btf_new_empty(base_btf);
+	return libbpf_ptr(btf_new_empty(base_btf));
 }
 
 static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
···
 
 struct btf *btf__new(const void *data, __u32 size)
 {
-	return btf_new(data, size, NULL);
+	return libbpf_ptr(btf_new(data, size, NULL));
 }
 
 static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
···
 		goto done;
 	}
 	btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
-	if (IS_ERR(btf))
+	err = libbpf_get_error(btf);
+	if (err)
 		goto done;
 
 	switch (gelf_getclass(elf)) {
···
 	}
 
 	if (btf_ext && btf_ext_data) {
-		*btf_ext = btf_ext__new(btf_ext_data->d_buf,
-					btf_ext_data->d_size);
-		if (IS_ERR(*btf_ext))
+		*btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
+		err = libbpf_get_error(*btf_ext);
+		if (err)
 			goto done;
 	} else if (btf_ext) {
 		*btf_ext = NULL;
···
 		elf_end(elf);
 	close(fd);
 
-	if (err)
-		return ERR_PTR(err);
-	/*
-	 * btf is always parsed before btf_ext, so no need to clean up
-	 * btf_ext, if btf loading failed
-	 */
-	if (IS_ERR(btf))
+	if (!err)
 		return btf;
-	if (btf_ext && IS_ERR(*btf_ext)) {
-		btf__free(btf);
-		err = PTR_ERR(*btf_ext);
-		return ERR_PTR(err);
-	}
-	return btf;
+
+	if (btf_ext)
+		btf_ext__free(*btf_ext);
+	btf__free(btf);
+
+	return ERR_PTR(err);
 }
 
 struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
 {
-	return btf_parse_elf(path, NULL, btf_ext);
+	return libbpf_ptr(btf_parse_elf(path, NULL, btf_ext));
 }
 
 struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
 {
-	return btf_parse_elf(path, base_btf, NULL);
+	return libbpf_ptr(btf_parse_elf(path, base_btf, NULL));
 }
 
 static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
···
 
 struct btf *btf__parse_raw(const char *path)
 {
-	return btf_parse_raw(path, NULL);
+	return libbpf_ptr(btf_parse_raw(path, NULL));
 }
 
 struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
 {
-	return btf_parse_raw(path, base_btf);
+	return libbpf_ptr(btf_parse_raw(path, base_btf));
 }
 
 static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
 {
 	struct btf *btf;
+	int err;
 
 	if (btf_ext)
 		*btf_ext = NULL;
 
 	btf = btf_parse_raw(path, base_btf);
-	if (!IS_ERR(btf) || PTR_ERR(btf) != -EPROTO)
+	err = libbpf_get_error(btf);
+	if (!err)
 		return btf;
-
+	if (err != -EPROTO)
+		return ERR_PTR(err);
 	return btf_parse_elf(path, base_btf, btf_ext);
 }
 
 struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
 {
-	return btf_parse(path, NULL, btf_ext);
+	return libbpf_ptr(btf_parse(path, NULL, btf_ext));
 }
 
 struct btf *btf__parse_split(const char *path, struct btf *base_btf)
 {
-	return btf_parse(path, base_btf, NULL);
+	return libbpf_ptr(btf_parse(path, base_btf, NULL));
 }
 
 static int compare_vsi_off(const void *_a, const void *_b)
···
 		}
 	}
 
-	return err;
+	return libbpf_err(err);
 }
 
 static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
···
 	int err = 0;
 
 	if (btf->fd >= 0)
-		return -EEXIST;
+		return libbpf_err(-EEXIST);
 
 retry_load:
 	if (log_buf_size) {
 		log_buf = malloc(log_buf_size);
 		if (!log_buf)
-			return -ENOMEM;
+			return libbpf_err(-ENOMEM);
 
 		*log_buf = 0;
 	}
···
 
 done:
 	free(log_buf);
-	return err;
+	return libbpf_err(err);
 }
 
 int btf__fd(const struct btf *btf)
···
 
 	data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
 	if (!data)
-		return NULL;
+		return errno = -ENOMEM, NULL;
 
 	btf->raw_size = data_sz;
 	if (btf->swapped_endian)
···
 	else if (offset - btf->start_str_off < btf->hdr->str_len)
 		return btf_strs_data(btf) + (offset - btf->start_str_off);
 	else
-		return NULL;
+		return errno = EINVAL, NULL;
 }
 
 const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
···
 int btf__get_from_id(__u32 id, struct btf **btf)
 {
 	struct btf *res;
-	int btf_fd;
+	int err, btf_fd;
 
 	*btf = NULL;
 	btf_fd = bpf_btf_get_fd_by_id(id);
 	if (btf_fd < 0)
-		return -errno;
+		return libbpf_err(-errno);
 
 	res = btf_get_from_fd(btf_fd, NULL);
+	err = libbpf_get_error(res);
+
 	close(btf_fd);
-	if (IS_ERR(res))
-		return PTR_ERR(res);
+
+	if (err)
+		return libbpf_err(err);
 
 	*btf = res;
 	return 0;
···
 	__s64 key_size, value_size;
 	__s32 container_id;
 
-	if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
-	    max_name) {
+	if (snprintf(container_name, max_name, "____btf_map_%s", map_name) == max_name) {
 		pr_warn("map:%s length of '____btf_map_%s' is too long\n",
 			map_name, map_name);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	container_id = btf__find_by_name(btf, container_name);
 	if (container_id < 0) {
 		pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
 			 map_name, container_name);
-		return container_id;
+		return libbpf_err(container_id);
 	}
 
 	container_type = btf__type_by_id(btf, container_id);
 	if (!container_type) {
 		pr_warn("map:%s cannot find BTF type for container_id:%u\n",
 			map_name, container_id);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
 		pr_warn("map:%s container_name:%s is an invalid container struct\n",
 			map_name, container_name);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	key = btf_members(container_type);
···
 	key_size = btf__resolve_size(btf, key->type);
 	if (key_size < 0) {
 		pr_warn("map:%s invalid BTF key_type_size\n", map_name);
-		return key_size;
+		return libbpf_err(key_size);
 	}
 
 	if (expected_key_size != key_size) {
 		pr_warn("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
 			map_name, (__u32)key_size, expected_key_size);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	value_size = btf__resolve_size(btf, value->type);
 	if (value_size < 0) {
 		pr_warn("map:%s invalid BTF value_type_size\n", map_name);
-		return value_size;
+		return libbpf_err(value_size);
 	}
 
 	if (expected_value_size != value_size) {
 		pr_warn("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
 			map_name, (__u32)value_size, expected_value_size);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	*key_type_id = key->type;
···
 
 	/* BTF needs to be in a modifiable state to build string lookup index */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	off = strset__find_str(btf->strs_set, s);
 	if (off < 0)
-		return off;
+		return libbpf_err(off);
 
 	return btf->start_str_off + off;
 }
···
 	}
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	off = strset__add_str(btf->strs_set, s);
 	if (off < 0)
-		return off;
+		return libbpf_err(off);
 
 	btf->hdr->str_len = strset__data_size(btf->strs_set);
 
···
 
 	err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	btf->hdr->type_len += data_sz;
 	btf->hdr->str_off += data_sz;
···
 
 	sz = btf_type_size(src_type);
 	if (sz < 0)
-		return sz;
+		return libbpf_err(sz);
 
 	/* deconstruct BTF, if necessary, and invalidate raw_data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	memcpy(t, src_type, sz);
 
 	err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	return btf_commit_type(btf, sz);
 }
···
 
 	/* non-empty name */
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	/* byte_sz must be power of 2 */
 	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* deconstruct BTF, if necessary, and invalidate raw_data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type) + sizeof(int);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	/* if something goes wrong later, we might end up with an extra string,
 	 * but that shouldn't be a problem, because BTF can't be constructed
···
 
 	/* non-empty name */
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* byte_sz must be one of the explicitly allowed values */
 	if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
 	    byte_sz != 16)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	name_off = btf__add_str(btf, name);
 	if (name_off < 0)
···
 	int sz, name_off = 0;
 
 	if (validate_type_id(ref_type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	if (name && name[0]) {
 		name_off = btf__add_str(btf, name);
···
 	int sz;
 
 	if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type) + sizeof(struct btf_array);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	t->name_off = 0;
 	t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
···
 	int sz, name_off = 0;
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	if (name && name[0]) {
 		name_off = btf__add_str(btf, name);
···
 
 	/* last type should be union/struct */
 	if (btf->nr_types == 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	t = btf_last_type(btf);
 	if (!btf_is_composite(t))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (validate_type_id(type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	/* best-effort bit field offset/size enforcement */
 	is_bitfield = bit_size || (bit_offset % 8 != 0);
 	if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* only offset 0 is allowed for unions */
 	if (btf_is_union(t) && bit_offset)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* decompose and invalidate raw data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_member);
 	m = btf_add_type_mem(btf, sz);
 	if (!m)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	if (name && name[0]) {
 		name_off = btf__add_str(btf, name);
···
 
 	/* byte_sz must be power of 2 */
 	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	if (name && name[0]) {
 		name_off = btf__add_str(btf, name);
···
 
 	/* last type should be BTF_KIND_ENUM */
 	if (btf->nr_types == 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	t = btf_last_type(btf);
 	if (!btf_is_enum(t))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* non-empty name */
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (value < INT_MIN || value > UINT_MAX)
-		return -E2BIG;
+		return libbpf_err(-E2BIG);
 
 	/* decompose and invalidate raw data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_enum);
 	v = btf_add_type_mem(btf, sz);
 	if (!v)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	name_off = btf__add_str(btf, name);
 	if (name_off < 0)
···
 int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
 {
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	switch (fwd_kind) {
 	case BTF_FWD_STRUCT:
···
 		 */
 		return btf__add_enum(btf, name, sizeof(int));
 	default:
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 }
 
···
 int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
 {
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
 }
···
 	int id;
 
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
 	    linkage != BTF_FUNC_EXTERN)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
 	if (id > 0) {
···
 
 		t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
 	}
-	return id;
+	return libbpf_err(id);
 }
 
 /*
···
 	int sz;
 
 	if (validate_type_id(ret_type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	/* start out with vlen=0; this will be adjusted when adding enum
 	 * values, if necessary
···
 	int sz, name_off = 0;
 
 	if (validate_type_id(type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* last type should be BTF_KIND_FUNC_PROTO */
 	if (btf->nr_types == 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	t = btf_last_type(btf);
 	if (!btf_is_func_proto(t))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* decompose and invalidate raw data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_param);
 	p = btf_add_type_mem(btf, sz);
 	if (!p)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	if (name && name[0]) {
 		name_off = btf__add_str(btf, name);
···
 
 	/* non-empty name */
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
 	    linkage != BTF_VAR_GLOBAL_EXTERN)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (validate_type_id(type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* deconstruct BTF, if necessary, and invalidate raw_data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type) + sizeof(struct btf_var);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	name_off = btf__add_str(btf, name);
 	if (name_off < 0)
···
 
 	/* non-empty name */
 	if (!name || !name[0])
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_type);
 	t = btf_add_type_mem(btf, sz);
 	if (!t)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	name_off = btf__add_str(btf, name);
 	if (name_off < 0)
···
 
 	/* last type should be BTF_KIND_DATASEC */
 	if (btf->nr_types == 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	t = btf_last_type(btf);
 	if (!btf_is_datasec(t))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (validate_type_id(var_type_id))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* decompose and invalidate raw data */
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	sz = sizeof(struct btf_var_secinfo);
 	v = btf_add_type_mem(btf, sz);
 	if (!v)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	v->type = var_type_id;
 	v->offset = offset;
···
 
 	err = btf_ext_parse_hdr(data, size);
 	if (err)
-		return ERR_PTR(err);
+		return libbpf_err_ptr(err);
 
 	btf_ext = calloc(1, sizeof(struct btf_ext));
 	if (!btf_ext)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 
 	btf_ext->data_size = size;
 	btf_ext->data = malloc(size);
···
 	}
 	memcpy(btf_ext->data, data, size);
 
-	if (btf_ext->hdr->hdr_len <
-	    offsetofend(struct btf_ext_header, line_info_len))
+	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
+		err = -EINVAL;
 		goto done;
+	}
+
 	err = btf_ext_setup_func_info(btf_ext);
 	if (err)
 		goto done;
···
 	if (err)
 		goto done;
 
-	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
+	if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) {
+		err = -EINVAL;
 		goto done;
+	}
+
 	err = btf_ext_setup_core_relos(btf_ext);
 	if (err)
 		goto done;
···
 done:
 	if (err) {
 		btf_ext__free(btf_ext);
-		return ERR_PTR(err);
+		return libbpf_err_ptr(err);
 	}
 
 	return btf_ext;
···
 		existing_len = (*cnt) * record_size;
 		data = realloc(*info, existing_len + records_len);
 		if (!data)
-			return -ENOMEM;
+			return libbpf_err(-ENOMEM);
 
 		memcpy(data + existing_len, sinfo->data, records_len);
 		/* adjust insn_off only, the rest data will be passed
···
 			__u32 *insn_off;
 
 			insn_off = data + existing_len + (i * record_size);
-			*insn_off = *insn_off / sizeof(struct bpf_insn) +
-				insns_cnt;
+			*insn_off = *insn_off / sizeof(struct bpf_insn) + insns_cnt;
 		}
 		*info = data;
 		*cnt += sinfo->num_info;
 		return 0;
 	}
 
-	return -ENOENT;
+	return libbpf_err(-ENOENT);
 }
 
 int btf_ext__reloc_func_info(const struct btf *btf,
···
 
 	if (IS_ERR(d)) {
 		pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (btf_ensure_modifiable(btf))
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	err = btf_dedup_prep(d);
 	if (err) {
···
 
 done:
 	btf_dedup_free(d);
-	return err;
+	return libbpf_err(err);
 }
 
 #define BTF_UNPROCESSED_ID ((__u32)-1)
···
 	char path[PATH_MAX + 1];
 	struct utsname buf;
 	struct btf *btf;
-	int i;
+	int i, err;
 
 	uname(&buf);
 
···
 			btf = btf__parse_raw(path);
 		else
 			btf = btf__parse_elf(path, NULL);
-
-		pr_debug("loading kernel BTF '%s': %ld\n",
-			 path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
-		if (IS_ERR(btf))
+		err = libbpf_get_error(btf);
+		pr_debug("loading kernel BTF '%s': %d\n", path, err);
+		if (err)
 			continue;
 
 		return btf;
 	}
 
 	pr_warn("failed to find valid kernel BTF\n");
-	return ERR_PTR(-ESRCH);
+	return libbpf_err_ptr(-ESRCH);
 }
 
 int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)

tools/lib/bpf/btf_dump.c

···
 
 	d = calloc(1, sizeof(struct btf_dump));
 	if (!d)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 
 	d->btf = btf;
 	d->btf_ext = btf_ext;
···
 	return d;
 err:
 	btf_dump__free(d);
-	return ERR_PTR(err);
+	return libbpf_err_ptr(err);
 }
 
 static int btf_dump_resize(struct btf_dump *d)
···
 	int err, i;
 
 	if (id > btf__get_nr_types(d->btf))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	err = btf_dump_resize(d);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	d->emit_queue_cnt = 0;
 	err = btf_dump_order_type(d, id, false);
 	if (err < 0)
-		return err;
+		return libbpf_err(err);
 
 	for (i = 0; i < d->emit_queue_cnt; i++)
 		btf_dump_emit_type(d, d->emit_queue[i], 0 /*top-level*/);
···
 	int lvl, err;
 
 	if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	err = btf_dump_resize(d);
 	if (err)
-		return -EINVAL;
+		return libbpf_err(err);
 
 	fname = OPTS_GET(opts, field_name, "");
 	lvl = OPTS_GET(opts, indent_level, 0);

tools/lib/bpf/libbpf.c

···
 
 	if (btf_data) {
 		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
-		if (IS_ERR(obj->btf)) {
-			err = PTR_ERR(obj->btf);
+		err = libbpf_get_error(obj->btf);
+		if (err) {
 			obj->btf = NULL;
-			pr_warn("Error loading ELF section %s: %d.\n",
-				BTF_ELF_SEC, err);
+			pr_warn("Error loading ELF section %s: %d.\n", BTF_ELF_SEC, err);
 			goto out;
 		}
 		/* enforce 8-byte pointers for BPF-targeted BTFs */
 		btf__set_pointer_size(obj->btf, 8);
-		err = 0;
 	}
 	if (btf_ext_data) {
 		if (!obj->btf) {
···
 				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
 			goto out;
 		}
-		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
-					    btf_ext_data->d_size);
-		if (IS_ERR(obj->btf_ext)) {
-			pr_warn("Error loading ELF section %s: %ld. Ignored and continue.\n",
-				BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
+		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
+		err = libbpf_get_error(obj->btf_ext);
+		if (err) {
+			pr_warn("Error loading ELF section %s: %d. Ignored and continue.\n",
+				BTF_EXT_ELF_SEC, err);
 			obj->btf_ext = NULL;
 			goto out;
 		}
···
 		return 0;
 
 	obj->btf_vmlinux = libbpf_find_kernel_btf();
-	if (IS_ERR(obj->btf_vmlinux)) {
-		err = PTR_ERR(obj->btf_vmlinux);
+	err = libbpf_get_error(obj->btf_vmlinux);
+	if (err) {
 		pr_warn("Error loading vmlinux BTF: %d\n", err);
 		obj->btf_vmlinux = NULL;
 		return err;
···
 		/* clone BTF to sanitize a copy and leave the original intact */
 		raw_data = btf__get_raw_data(obj->btf, &sz);
 		kern_btf = btf__new(raw_data, sz);
-		if (IS_ERR(kern_btf))
-			return PTR_ERR(kern_btf);
+		err = libbpf_get_error(kern_btf);
+		if (err)
+			return err;
 
 		/* enforce 8-byte pointers for BPF-targeted BTFs */
 		btf__set_pointer_size(obj->btf, 8);
···
 		if (pos->sec_name && !strcmp(pos->sec_name, title))
 			return pos;
 	}
-	return NULL;
+	return errno = ENOENT, NULL;
 }
 
 static bool prog_is_subprog(const struct bpf_object *obj,
···
 		if (!strcmp(prog->name, name))
 			return prog;
 	}
-	return NULL;
+	return errno = ENOENT, NULL;
 }
 
 static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
···
 
 	err = bpf_obj_get_info_by_fd(fd, &info, &len);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	new_name = strdup(info.name);
 	if (!new_name)
-		return -errno;
+		return libbpf_err(-errno);
 
 	new_fd = open("/", O_RDONLY | O_CLOEXEC);
 	if (new_fd < 0) {
···
 	close(new_fd);
 err_free_new_name:
 	free(new_name);
-	return err;
+	return libbpf_err(err);
 }
 
 __u32 bpf_map__max_entries(const struct bpf_map *map)
···
 struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
 {
 	if (!bpf_map_type__is_map_in_map(map->def.type))
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	return map->inner_map;
 }
···
 int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->def.max_entries = max_entries;
 	return 0;
 }
···
 int bpf_map__resize(struct bpf_map *map, __u32 max_entries)
 {
 	if (!map || !max_entries)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	return bpf_map__set_max_entries(map, max_entries);
 }
···
 		}
 
 		btf = btf_get_from_fd(fd, obj->btf_vmlinux);
-		if (IS_ERR(btf)) {
-			pr_warn("failed to load module [%s]'s BTF object #%d: %ld\n",
-				name, id, PTR_ERR(btf));
-			err = PTR_ERR(btf);
+		err = libbpf_get_error(btf);
+		if (err) {
+			pr_warn("failed to load module [%s]'s BTF object #%d: %d\n",
+				name, id, err);
 			goto err_out;
 		}
 
···
 
 	if (targ_btf_path) {
 		obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
-		if (IS_ERR_OR_NULL(obj->btf_vmlinux_override)) {
-			err = PTR_ERR(obj->btf_vmlinux_override);
+		err = libbpf_get_error(obj->btf_vmlinux_override);
+		if (err) {
 			pr_warn("failed to parse target BTF: %d\n", err);
 			return err;
 		}
···
 
 	if (prog->obj->loaded) {
 		pr_warn("prog '%s': can't load after object was loaded\n", prog->name);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if ((prog->type == BPF_PROG_TYPE_TRACING ||
···
 
 		err = libbpf_find_attach_btf_id(prog, &btf_obj_fd, &btf_type_id);
 		if (err)
-			return err;
+			return libbpf_err(err);
 
 		prog->attach_btf_obj_fd = btf_obj_fd;
 		prog->attach_btf_id = btf_type_id;
···
 		if (prog->preprocessor) {
 			pr_warn("Internal error: can't load program '%s'\n",
 				prog->name);
-			return -LIBBPF_ERRNO__INTERNAL;
+			return libbpf_err(-LIBBPF_ERRNO__INTERNAL);
 		}
 
 		prog->instances.fds = malloc(sizeof(int));
 		if (!prog->instances.fds) {
 			pr_warn("Not enough memory for BPF fds\n");
-			return -ENOMEM;
+			return libbpf_err(-ENOMEM);
 		}
 		prog->instances.nr = 1;
 		prog->instances.fds[0] = -1;
···
 		pr_warn("failed to load program '%s'\n", prog->name);
 	zfree(&prog->insns);
 	prog->insns_cnt = 0;
-	return err;
+	return libbpf_err(err);
 }
 
 static int
···
 
 struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr)
 {
-	return __bpf_object__open_xattr(attr, 0);
+	return libbpf_ptr(__bpf_object__open_xattr(attr, 0));
 }
 
 struct bpf_object *bpf_object__open(const char *path)
···
 		.prog_type	= BPF_PROG_TYPE_UNSPEC,
 	};
 
-	return bpf_object__open_xattr(&attr);
+	return libbpf_ptr(__bpf_object__open_xattr(&attr, 0));
 }
 
 struct bpf_object *
 bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
 {
 	if (!path)
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 
 	pr_debug("loading %s\n", path);
 
-	return __bpf_object__open(path, NULL, 0, opts);
+	return libbpf_ptr(__bpf_object__open(path, NULL, 0, opts));
 }
 
 struct bpf_object *
···
 		     const struct bpf_object_open_opts *opts)
 {
 	if (!obj_buf || obj_buf_sz == 0)
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 
-	return __bpf_object__open(NULL, obj_buf, obj_buf_sz, opts);
+	return libbpf_ptr(__bpf_object__open(NULL, obj_buf, obj_buf_sz, opts));
 }
 
 struct bpf_object *
···
 
 	/* returning NULL is wrong, but backwards-compatible */
 	if (!obj_buf || obj_buf_sz == 0)
-		return NULL;
+		return errno = EINVAL, NULL;
 
-	return bpf_object__open_mem(obj_buf, obj_buf_sz, &opts);
+	return libbpf_ptr(__bpf_object__open(NULL, obj_buf, obj_buf_sz, &opts));
 }
 
 int bpf_object__unload(struct bpf_object *obj)
···
 	size_t i;
 
 	if (!obj)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	for (i = 0; i < obj->nr_maps; i++) {
 		zclose(obj->maps[i].fd);
···
 	int err, i;
 
 	if (!attr)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	obj = attr->obj;
 	if (!obj)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (obj->loaded) {
 		pr_warn("object '%s': load can't be attempted twice\n", obj->name);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (obj->gen_loader)
···
 
 	bpf_object__unload(obj);
 	pr_warn("failed to load object '%s'\n", obj->path);
-	return err;
+	return libbpf_err(err);
 }
 
 int bpf_object__load(struct bpf_object *obj)
···
 
 	err = make_parent_dir(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	err = check_path(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	if (prog == NULL) {
 		pr_warn("invalid program pointer\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (instance < 0 || instance >= prog->instances.nr) {
 		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
 			instance, prog->name, prog->instances.nr);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (bpf_obj_pin(prog->instances.fds[instance], path)) {
 		err = -errno;
 		cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
 		pr_warn("failed to pin program: %s\n", cp);
-		return err;
+		return libbpf_err(err);
 	}
 	pr_debug("pinned program '%s'\n", path);
 
···
 
 	err = check_path(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	if (prog == NULL) {
 		pr_warn("invalid program pointer\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (instance < 0 || instance >= prog->instances.nr) {
 		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
 			instance, prog->name, prog->instances.nr);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	err = unlink(path);
 	if (err != 0)
-		return -errno;
+		return libbpf_err(-errno);
+
 	pr_debug("unpinned program '%s'\n", path);
 
 	return 0;
···
 
 	err = make_parent_dir(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	err = check_path(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	if (prog == NULL) {
 		pr_warn("invalid program pointer\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (prog->instances.nr <= 0) {
 		pr_warn("no instances of prog %s to pin\n", prog->name);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (prog->instances.nr == 1) {
···
 
 	rmdir(path);
 
-	return err;
+	return libbpf_err(err);
 }
 
 int bpf_program__unpin(struct bpf_program *prog, const char *path)
···
 
 	err = check_path(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	if (prog == NULL) {
 		pr_warn("invalid program pointer\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (prog->instances.nr <= 0) {
 		pr_warn("no instances of prog %s to pin\n", prog->name);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (prog->instances.nr == 1) {
···
 
 		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
 		if (len < 0)
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		else if (len >= PATH_MAX)
-			return -ENAMETOOLONG;
+			return libbpf_err(-ENAMETOOLONG);
 
 		err = bpf_program__unpin_instance(prog, buf, i);
 		if (err)
···
 
 	err = rmdir(path);
 	if (err)
-		return -errno;
+		return libbpf_err(-errno);
 
 	return 0;
 }
···
 
 	if (map == NULL) {
 		pr_warn("invalid map pointer\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (map->pin_path) {
 		if (path && strcmp(path, map->pin_path)) {
 			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
 				bpf_map__name(map), map->pin_path, path);
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		} else if (map->pinned) {
 			pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
 				 bpf_map__name(map), map->pin_path);
···
 		if (!path) {
 			pr_warn("missing a path to pin map '%s' at\n",
 				bpf_map__name(map));
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		} else if (map->pinned) {
 			pr_warn("map '%s' already pinned\n", bpf_map__name(map));
-			return -EEXIST;
+			return libbpf_err(-EEXIST);
 		}
 
 		map->pin_path = strdup(path);
···
 
 	err = make_parent_dir(map->pin_path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	err = check_path(map->pin_path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	if (bpf_obj_pin(map->fd, map->pin_path)) {
 		err = -errno;
···
 out_err:
 	cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
 	pr_warn("failed to pin map: %s\n", cp);
-	return err;
+	return libbpf_err(err);
 }
 
 int bpf_map__unpin(struct bpf_map *map, const char *path)
···
 
 	if (map == NULL) {
 		pr_warn("invalid map pointer\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	if (map->pin_path) {
 		if (path && strcmp(path, map->pin_path)) {
 			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
 				bpf_map__name(map), map->pin_path, path);
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		}
 		path = map->pin_path;
 	} else if (!path) {
 		pr_warn("no path to unpin map '%s' from\n",
 			bpf_map__name(map));
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	err = check_path(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	err = unlink(path);
 	if (err != 0)
-		return -errno;
+		return libbpf_err(-errno);
 
 	map->pinned = false;
 	pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
···
 	if (path) {
 		new = strdup(path);
 		if (!new)
-			return -errno;
+			return libbpf_err(-errno);
 	}
 
 	free(map->pin_path);
···
 	int err;
 
 	if (!obj)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 
 	if (!obj->loaded) {
 		pr_warn("object not yet loaded; load it first\n");
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 	}
 
 	bpf_object__for_each_map(map, obj) {
···
 		bpf_map__unpin(map, NULL);
 	}
 
-	return err;
+	return libbpf_err(err);
 }
 
 int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
···
 	int err;
 
 	if (!obj)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 
 	bpf_object__for_each_map(map, obj) {
 		char *pin_path = NULL;
···
 			len = snprintf(buf, PATH_MAX, "%s/%s", path,
 				       bpf_map__name(map));
 			if (len < 0)
-				return -EINVAL;
+				return libbpf_err(-EINVAL);
 			else if (len >= PATH_MAX)
-				return -ENAMETOOLONG;
+				return libbpf_err(-ENAMETOOLONG);
 			sanitize_pin_path(buf);
 			pin_path = buf;
 		} else if (!map->pin_path) {
···
 
 		err = bpf_map__unpin(map, pin_path);
 		if (err)
-			return err;
+			return libbpf_err(err);
 	}
 
 	return 0;
···
 	int err;
 
 	if (!obj)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 
 	if (!obj->loaded) {
 		pr_warn("object not yet loaded; load it first\n");
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 	}
 
 	bpf_object__for_each_program(prog, obj) {
···
 		bpf_program__unpin(prog, buf);
 	}
 
-	return err;
+	return libbpf_err(err);
 }
 
 int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
···
 	int err;
 
 	if (!obj)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 
 	bpf_object__for_each_program(prog, obj) {
 		char buf[PATH_MAX];
···
 		len = snprintf(buf, PATH_MAX, "%s/%s", path,
 			       prog->pin_name);
 		if (len < 0)
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		else if (len >= PATH_MAX)
-			return -ENAMETOOLONG;
+			return libbpf_err(-ENAMETOOLONG);
 
 		err = bpf_program__unpin(prog, buf);
 		if (err)
-			return err;
+			return libbpf_err(err);
 	}
 
 	return 0;
···
 
 	err = bpf_object__pin_maps(obj, path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	err = bpf_object__pin_programs(obj, path);
 	if (err) {
 		bpf_object__unpin_maps(obj, path);
-		return err;
+		return libbpf_err(err);
 	}
 
 	return 0;
···
 
 const char *bpf_object__name(const struct bpf_object *obj)
 {
-	return obj ? obj->name : ERR_PTR(-EINVAL);
+	return obj ? obj->name : libbpf_err_ptr(-EINVAL);
 }
 
 unsigned int bpf_object__kversion(const struct bpf_object *obj)
···
 int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version)
 {
 	if (obj->loaded)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	obj->kern_version = kern_version;
 
···
 
 void *bpf_object__priv(const struct bpf_object *obj)
 {
-	return obj ? obj->priv : ERR_PTR(-EINVAL);
+	return obj ? obj->priv : libbpf_err_ptr(-EINVAL);
 }
 
 int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts)
···
 
 	if (p->obj != obj) {
 		pr_warn("error: program handler doesn't match object\n");
-		return NULL;
+		return errno = EINVAL, NULL;
 	}
 
 	idx = (p - obj->programs) + (forward ? 1 : -1);
···
 
 void *bpf_program__priv(const struct bpf_program *prog)
 {
-	return prog ? prog->priv : ERR_PTR(-EINVAL);
+	return prog ? prog->priv : libbpf_err_ptr(-EINVAL);
 }
 
 void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
···
 		title = strdup(title);
 		if (!title) {
 			pr_warn("failed to strdup program title\n");
-			return ERR_PTR(-ENOMEM);
+			return libbpf_err_ptr(-ENOMEM);
 		}
 	}
 
···
 int bpf_program__set_autoload(struct bpf_program *prog, bool autoload)
 {
 	if (prog->obj->loaded)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	prog->load = autoload;
 	return 0;
···
 	int *instances_fds;
 
 	if (nr_instances <= 0 || !prep)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (prog->instances.nr > 0 || prog->instances.fds) {
 		pr_warn("Can't set pre-processor after loading\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	instances_fds = malloc(sizeof(int) * nr_instances);
 	if (!instances_fds) {
 		pr_warn("alloc memory failed for fds\n");
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 	}
 
 	/* fill all fd with -1 */
···
 	int fd;
 
 	if (!prog)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (n >= prog->instances.nr || n < 0) {
 		pr_warn("Can't get the %dth fd from program %s: only %d instances\n",
 			n, prog->name, prog->instances.nr);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	fd = prog->instances.fds[n];
 	if (fd < 0) {
 		pr_warn("%dth instance of program '%s' is invalid\n",
 			n, prog->name);
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 	}
 
 	return fd;
···
 int bpf_program__set_##NAME(struct bpf_program *prog)		\
 {								\
 	if (!prog)						\
-		return -EINVAL;					\
+		return libbpf_err(-EINVAL);			\
 	bpf_program__set_type(prog, TYPE);			\
 	return 0;						\
 }								\
···
 	char *type_names;
 
 	if (!name)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	sec_def = find_sec_def(name);
 	if (sec_def) {
···
 		free(type_names);
 	}
 
-	return -ESRCH;
+	return libbpf_err(-ESRCH);
 }
 
 static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
···
 	int err;
 
 	btf = libbpf_find_kernel_btf();
-	if (IS_ERR(btf)) {
+	err = libbpf_get_error(btf);
+	if (err) {
 		pr_warn("vmlinux BTF is not found\n");
-		return -EINVAL;
+		return libbpf_err(err);
 	}
 
 	err = find_attach_btf_id(btf, name, attach_type);
···
 		pr_warn("%s is not found in vmlinux BTF\n", name);
 
 	btf__free(btf);
-	return err;
+	return libbpf_err(err);
 }
 
 static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
···
 	int err = -EINVAL;
 
 	info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
-	if (IS_ERR_OR_NULL(info_linear)) {
+	err = libbpf_get_error(info_linear);
+	if (err) {
 		pr_warn("failed get_prog_info_linear for FD %d\n",
 			attach_prog_fd);
-		return -EINVAL;
+		return err;
 	}
 	info = &info_linear->info;
 	if (!info->btf_id) {
···
 	int i;
 
 	if (!name)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
 		if (strncmp(name, section_defs[i].sec, section_defs[i].len))
 			continue;
 		if (!section_defs[i].is_attachable)
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		*attach_type = section_defs[i].expected_attach_type;
 		return 0;
 	}
···
 		free(type_names);
 	}
 
-	return -EINVAL;
+	return libbpf_err(-EINVAL);
 }
 
 int bpf_map__fd(const struct bpf_map *map)
 {
-	return map ? map->fd : -EINVAL;
+	return map ? map->fd : libbpf_err(-EINVAL);
 }
 
 const struct bpf_map_def *bpf_map__def(const struct bpf_map *map)
 {
-	return map ? &map->def : ERR_PTR(-EINVAL);
+	return map ? &map->def : libbpf_err_ptr(-EINVAL);
 }
 
 const char *bpf_map__name(const struct bpf_map *map)
···
 int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->def.type = type;
 	return 0;
 }
···
 int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->def.map_flags = flags;
 	return 0;
 }
···
 int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->numa_node = numa_node;
 	return 0;
 }
···
 int bpf_map__set_key_size(struct bpf_map *map, __u32 size)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->def.key_size = size;
 	return 0;
 }
···
 int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->def.value_size = size;
 	return 0;
 }
···
 		     bpf_map_clear_priv_t clear_priv)
 {
 	if (!map)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (map->priv) {
 		if (map->clear_priv)
···
 
 void *bpf_map__priv(const struct bpf_map *map)
 {
-	return map ? map->priv : ERR_PTR(-EINVAL);
+	return map ? map->priv : libbpf_err_ptr(-EINVAL);
 }
 
 int bpf_map__set_initial_value(struct bpf_map *map,
···
 {
 	if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG ||
 	    size != map->def.value_size || map->fd >= 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	memcpy(map->mmaped, data, size);
 	return 0;
···
 int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
 {
 	if (map->fd >= 0)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	map->map_ifindex = ifindex;
 	return 0;
 }
···
 {
 	if (!bpf_map_type__is_map_in_map(map->def.type)) {
 		pr_warn("error: unsupported map type\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 	if (map->inner_map_fd != -1) {
 		pr_warn("error: inner_map_fd already specified\n");
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 	zfree(&map->inner_map);
 	map->inner_map_fd = fd;
···
 	struct bpf_map *s, *e;
 
 	if (!obj || !obj->maps)
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	s = obj->maps;
 	e = obj->maps + obj->nr_maps;
···
 	if ((m < s) || (m >= e)) {
 		pr_warn("error in %s: map handler doesn't belong to object\n",
 			 __func__);
-		return NULL;
+		return errno = EINVAL, NULL;
 	}
 
 	idx = (m - obj->maps) + i;
···
 		if (pos->name && !strcmp(pos->name, name))
 			return pos;
 	}
-	return NULL;
+	return errno = ENOENT, NULL;
 }
 
 int
···
 struct bpf_map *
 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
 {
-	return ERR_PTR(-ENOTSUP);
+	return libbpf_err_ptr(-ENOTSUP);
 }
 
 long libbpf_get_error(const void *ptr)
 {
-	return PTR_ERR_OR_ZERO(ptr);
+	if (!IS_ERR_OR_NULL(ptr))
+		return 0;
+
+	if (IS_ERR(ptr))
+		errno = -PTR_ERR(ptr);
+
+	/* If ptr == NULL, then errno should be already set by the failing
+	 * API, because libbpf never returns NULL on success and it now always
+	 * sets errno on error. So no extra errno handling for ptr == NULL
+	 * case.
+	 */
+	return -errno;
 }
 
 int bpf_prog_load(const char *file, enum bpf_prog_type type,
···
 	int err;
 
 	if (!attr)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (!attr->file)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	open_attr.file = attr->file;
 	open_attr.prog_type = attr->prog_type;
 
 	obj = bpf_object__open_xattr(&open_attr);
-	if (IS_ERR_OR_NULL(obj))
-		return -ENOENT;
+	err = libbpf_get_error(obj);
+	if (err)
+		return libbpf_err(-ENOENT);
 
 	bpf_object__for_each_program(prog, obj) {
 		enum bpf_attach_type attach_type = attr->expected_attach_type;
···
 			 * didn't provide a fallback type, too bad...
 			 */
 			bpf_object__close(obj);
-			return -EINVAL;
+			return libbpf_err(-EINVAL);
 		}
 
 		prog->prog_ifindex = attr->ifindex;
···
 	if (!first_prog) {
 		pr_warn("object file doesn't contain bpf program\n");
 		bpf_object__close(obj);
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 	}
 
 	err = bpf_object__load(obj);
 	if (err) {
 		bpf_object__close(obj);
-		return err;
+		return libbpf_err(err);
 	}
 
 	*pobj = obj;
···
 /* Replace link's underlying BPF program with the new one */
 int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
 {
-	return bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
+	int ret;
+	
+	ret = bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
+	return libbpf_err_errno(ret);
 }
 
 /* Release "ownership" of underlying BPF resource (typically, BPF program
···
 		free(link->pin_path);
 	free(link);
 
-	return err;
+	return libbpf_err(err);
 }
 
 int bpf_link__fd(const struct bpf_link *link)
···
 
 static int bpf_link__detach_fd(struct bpf_link *link)
 {
-	return close(link->fd);
+	return libbpf_err_errno(close(link->fd));
 }
 
 struct bpf_link *bpf_link__open(const char *path)
···
 	if (fd < 0) {
 		fd = -errno;
 		pr_warn("failed to open link at %s: %d\n", path, fd);
-		return ERR_PTR(fd);
+		return libbpf_err_ptr(fd);
 	}
 
 	link = calloc(1, sizeof(*link));
 	if (!link) {
 		close(fd);
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	}
 	link->detach = &bpf_link__detach_fd;
 	link->fd = fd;
···
 	link->pin_path = strdup(path);
 	if (!link->pin_path) {
 		bpf_link__destroy(link);
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	}
 
 	return link;
···
 	int err;
 
 	if (link->pin_path)
-		return -EBUSY;
+		return libbpf_err(-EBUSY);
 	err = make_parent_dir(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 	err = check_path(path);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	link->pin_path = strdup(path);
 	if (!link->pin_path)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 
 	if (bpf_obj_pin(link->fd, link->pin_path)) {
 		err = -errno;
 		zfree(&link->pin_path);
-		return err;
+		return libbpf_err(err);
 	}
 
 	pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
···
 	int err;
 
 	if (!link->pin_path)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	err = unlink(link->pin_path);
 	if (err != 0)
-		return -errno;
+		return libbpf_err_errno(err);
 
 	pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
 	zfree(&link->pin_path);
···
 		err = -errno;
 
 	close(link->fd);
-	return err;
+	return libbpf_err(err);
 }
 
-struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
-						int pfd)
+struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd)
 {
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
···
 	if (pfd < 0) {
 		pr_warn("prog '%s': invalid perf event FD %d\n",
 			prog->name, pfd);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
 		pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
 			prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	link = calloc(1, sizeof(*link));
 	if (!link)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	link->detach = &bpf_link__detach_perf_event;
 	link->fd = pfd;
 
···
 		if (err == -EPROTO)
 			pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
 				prog->name, pfd);
-		return ERR_PTR(err);
+		return libbpf_err_ptr(err);
 	}
 	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
 		err = -errno;
 		free(link);
 		pr_warn("prog '%s': failed to enable pfd %d: %s\n",
 			prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		return ERR_PTR(err);
+		return libbpf_err_ptr(err);
 	}
 	return link;
 }
···
 		pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n",
 			prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(pfd);
+		return libbpf_err_ptr(pfd);
 	}
 	link = bpf_program__attach_perf_event(prog, pfd);
-	if (IS_ERR(link)) {
+	err = libbpf_get_error(link);
+	if (err) {
 		close(pfd);
-		err = PTR_ERR(link);
 		pr_warn("prog '%s': failed to attach to %s '%s': %s\n",
 			prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		return link;
+		return libbpf_err_ptr(err);
 	}
 	return link;
 }
···
 			prog->name, retprobe ? "uretprobe" : "uprobe",
 			binary_path, func_offset,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(pfd);
+		return libbpf_err_ptr(pfd);
 	}
 	link = bpf_program__attach_perf_event(prog, pfd);
-	if (IS_ERR(link)) {
+	err = libbpf_get_error(link);
+	if (err) {
 		close(pfd);
-		err = PTR_ERR(link);
 		pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
 			prog->name, retprobe ? "uretprobe" : "uprobe",
 			binary_path, func_offset,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		return link;
+		return libbpf_err_ptr(err);
 	}
 	return link;
 }
···
 		pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
 			prog->name, tp_category, tp_name,
 			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(pfd);
+		return libbpf_err_ptr(pfd);
 	}
 	link = bpf_program__attach_perf_event(prog, pfd);
-	if (IS_ERR(link)) {
+	err = libbpf_get_error(link);
+	if (err) {
 		close(pfd);
-		err = PTR_ERR(link);
 		pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
 			prog->name, tp_category, tp_name,
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
-		return link;
+		return libbpf_err_ptr(err);
 	}
 	return link;
 }
···
 
 	sec_name = strdup(prog->sec_name);
 	if (!sec_name)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 
 	/* extract "tp/<category>/<name>" */
 	tp_cat = sec_name + sec->len;
 	tp_name = strchr(tp_cat, '/');
 	if (!tp_name) {
-		link = ERR_PTR(-EINVAL);
-		goto out;
+		free(sec_name);
+		return libbpf_err_ptr(-EINVAL);
 	}
 	*tp_name = '\0';
 	tp_name++;
 
 	link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
-out:
 	free(sec_name);
 	return link;
 }
···
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	link = calloc(1, sizeof(*link));
 	if (!link)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	link->detach = &bpf_link__detach_fd;
 
 	pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
···
 		free(link);
 		pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
 			prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(pfd);
+		return libbpf_err_ptr(pfd);
 	}
 	link->fd = pfd;
 	return link;
···
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	link = calloc(1, sizeof(*link));
 	if (!link)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	link->detach = &bpf_link__detach_fd;
 
 	pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
···
 		free(link);
 		pr_warn("prog '%s': failed to attach: %s\n",
 			prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(pfd);
+		return libbpf_err_ptr(pfd);
 	}
 	link->fd = pfd;
 	return (struct bpf_link *)link;
···
 	return bpf_program__attach_lsm(prog);
 }
 
-static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
-				    struct bpf_program *prog)
-{
-	return bpf_program__attach_iter(prog, NULL);
-}
-
 static struct bpf_link *
 bpf_program__attach_fd(struct bpf_program *prog, int target_fd, int btf_id,
 		       const char *target_name)
···
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	link = calloc(1, sizeof(*link));
 	if (!link)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	link->detach = &bpf_link__detach_fd;
 
 	attach_type = bpf_program__get_expected_attach_type(prog);
···
 		pr_warn("prog '%s': failed to attach to %s: %s\n",
 			prog->name, target_name,
 			libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(link_fd);
+		return libbpf_err_ptr(link_fd);
 	}
 	link->fd = link_fd;
 	return link;
···
 	if (!!target_fd != !!attach_func_name) {
 		pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
 			prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	if (prog->type != BPF_PROG_TYPE_EXT) {
 		pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",
 			prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	if (target_fd) {
 		btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
 		if (btf_id < 0)
-			return ERR_PTR(btf_id);
+			return libbpf_err_ptr(btf_id);
 
 		return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
 	} else {
···
 	__u32 target_fd = 0;
 
 	if (!OPTS_VALID(opts, bpf_iter_attach_opts))
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 
 	link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
 	link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
···
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 	}
 
 	link = calloc(1, sizeof(*link));
 	if (!link)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 	link->detach = &bpf_link__detach_fd;
 
 	link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
···
 		free(link);
 		pr_warn("prog '%s': failed to attach to iterator: %s\n",
 			prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
-		return ERR_PTR(link_fd);
+		return libbpf_err_ptr(link_fd);
 	}
 	link->fd = link_fd;
 	return link;
+}
+
+static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
+				    struct bpf_program *prog)
+{
+	return bpf_program__attach_iter(prog, NULL);
 }
 
 struct bpf_link *bpf_program__attach(struct bpf_program *prog)
···
 
 	sec_def = find_sec_def(prog->sec_name);
 	if (!sec_def || !sec_def->attach_fn)
-		return ERR_PTR(-ESRCH);
+		return libbpf_err_ptr(-ESRCH);
 
 	return sec_def->attach_fn(sec_def, prog);
 }
···
 	int err;
 
 	if (!bpf_map__is_struct_ops(map) || map->fd == -1)
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 
 	link = calloc(1, sizeof(*link));
 	if (!link)
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 
 	st_ops = map->st_ops;
 	for (i = 0; i < btf_vlen(st_ops->type); i++) {
···
 	if (err) {
 		err = -errno;
 		free(link);
-		return ERR_PTR(err);
+		return libbpf_err_ptr(err);
 	}
 
 	link->detach = bpf_link__detach_struct_ops;
···
 	}
 
 	ring_buffer_write_tail(header, data_tail);
-	return ret;
+	return libbpf_err(ret);
 }
 
 struct perf_buffer;
···
 	p.lost_cb = opts ? opts->lost_cb : NULL;
 	p.ctx = opts ? opts->ctx : NULL;
 
-	return __perf_buffer__new(map_fd, page_cnt, &p);
+	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
 }
 
 struct perf_buffer *
···
 	p.cpus = opts->cpus;
 	p.map_keys = opts->map_keys;
 
-	return __perf_buffer__new(map_fd, page_cnt, &p);
+	return libbpf_ptr(__perf_buffer__new(map_fd, page_cnt, &p));
 }
 
 static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
···
 	int i, cnt, err;
 
 	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
+	if (cnt < 0)
+		return libbpf_err_errno(cnt);
+
 	for (i = 0; i < cnt; i++) {
 		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
 
 		err = perf_buffer__process_records(pb, cpu_buf);
 		if (err) {
 			pr_warn("error while processing records: %d\n", err);
-			return err;
+			return libbpf_err(err);
 		}
 	}
-	return cnt < 0 ? -errno : cnt;
+	return cnt;
 }
 
 /* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer
···
 	struct perf_cpu_buf *cpu_buf;
 
 	if (buf_idx >= pb->cpu_cnt)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	cpu_buf = pb->cpu_bufs[buf_idx];
 	if (!cpu_buf)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 
 	return cpu_buf->fd;
 }
···
 	struct perf_cpu_buf *cpu_buf;
 
 	if (buf_idx >= pb->cpu_cnt)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	cpu_buf = pb->cpu_bufs[buf_idx];
 	if (!cpu_buf)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 
 	return perf_buffer__process_records(pb, cpu_buf);
 }
···
 		err = perf_buffer__process_records(pb, cpu_buf);
 		if (err) {
 			pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err);
-			return err;
+			return libbpf_err(err);
 		}
 	}
 	return 0;
···
 	void *ptr;
 
 	if (arrays >> BPF_PROG_INFO_LAST_ARRAY)
-		return ERR_PTR(-EINVAL);
+		return libbpf_err_ptr(-EINVAL);
 
 	/* step 1: get array dimensions */
 	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
 	if (err) {
 		pr_debug("can't get prog info: %s", strerror(errno));
-		return ERR_PTR(-EFAULT);
+		return libbpf_err_ptr(-EFAULT);
 	}
 
 	/* step 2: calculate total size of all arrays */
···
 	data_len = roundup(data_len, sizeof(__u64));
 	info_linear = malloc(sizeof(struct bpf_prog_info_linear) + data_len);
 	if (!info_linear)
-		return ERR_PTR(-ENOMEM);
+		return libbpf_err_ptr(-ENOMEM);
 
 	/* step 4: fill data to info_linear->info */
 	info_linear->arrays = arrays;
···
 	if (err) {
 		pr_debug("can't get prog info: %s", strerror(errno));
 		free(info_linear);
-		return ERR_PTR(-EFAULT);
+		return libbpf_err_ptr(-EFAULT);
 	}
 
 	/* step 6: verify the data */
···
 	int btf_obj_fd = 0, btf_id = 0, err;
 
 	if (!prog || attach_prog_fd < 0 || !attach_func_name)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (prog->obj->loaded)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (attach_prog_fd) {
 		btf_id = libbpf_find_prog_btf_id(attach_func_name,
 						 attach_prog_fd);
 		if (btf_id < 0)
-			return btf_id;
+			return libbpf_err(btf_id);
 	} else {
 		/* load btf_vmlinux, if not yet */
 		err = bpf_object__load_vmlinux_btf(prog->obj, true);
 		if (err)
-			return err;
+			return libbpf_err(err);
 		err = find_kernel_btf_id(prog->obj, attach_func_name,
 					 prog->expected_attach_type,
 					 &btf_obj_fd, &btf_id);
 		if (err)
-			return err;
+			return libbpf_err(err);
 	}
 
 	prog->attach_btf_id = btf_id;
···
 
 	err = parse_cpu_mask_file(fcpu, &mask, &n);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	tmp_cpus = 0;
 	for (i = 0; i < n; i++) {
···
 		.object_name = s->name,
 	);
 	struct bpf_object *obj;
-	int i;
+	int i, err;
 
 	/* Attempt to preserve opts->object_name, unless overriden by user
 	 * explicitly. Overwriting object name for skeletons is discouraged,
···
 	}
 
 	obj = bpf_object__open_mem(s->data, s->data_sz, &skel_opts);
-	if (IS_ERR(obj)) {
-		pr_warn("failed to initialize skeleton BPF object '%s': %ld\n",
-			s->name, PTR_ERR(obj));
-		return PTR_ERR(obj);
+	err = libbpf_get_error(obj);
+	if (err) {
+		pr_warn("failed to initialize skeleton BPF object '%s': %d\n",
+			s->name, err);
+		return libbpf_err(err);
 	}
 
 	*s->obj = obj;
···
 		*map = bpf_object__find_map_by_name(obj, name);
 		if (!*map) {
 			pr_warn("failed to find skeleton map '%s'\n", name);
-			return -ESRCH;
+			return libbpf_err(-ESRCH);
 		}
 
 		/* externs shouldn't be pre-setup from user code */
···
 		*prog = bpf_object__find_program_by_name(obj, name);
 		if (!*prog) {
 			pr_warn("failed to find skeleton program '%s'\n", name);
-			return -ESRCH;
+			return libbpf_err(-ESRCH);
 		}
 	}
 
···
 	err = bpf_object__load(*s->obj);
 	if (err) {
 		pr_warn("failed to load BPF skeleton '%s': %d\n", s->name, err);
-		return err;
+		return libbpf_err(err);
 	}
 
 	for (i = 0; i < s->map_cnt; i++) {
···
 			*mmaped = NULL;
 			pr_warn("failed to re-mmap() map '%s': %d\n",
 				 bpf_map__name(map), err);
-			return err;
+			return libbpf_err(err);
 		}
 	}
 
···
 
 int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
 {
-	int i;
+	int i, err;
 
 	for (i = 0; i < s->prog_cnt; i++) {
 		struct bpf_program *prog = *s->progs[i].prog;
···
 			continue;
 
 		*link = sec_def->attach_fn(sec_def, prog);
-		if (IS_ERR(*link)) {
-			pr_warn("failed to auto-attach program '%s': %ld\n",
-				bpf_program__name(prog), PTR_ERR(*link));
-			return PTR_ERR(*link);
+		err = libbpf_get_error(*link);
+		if (err) {
+			pr_warn("failed to auto-attach program '%s': %d\n",
+				bpf_program__name(prog), err);
+			return libbpf_err(err);
 		}
 	}
 

tools/lib/bpf/libbpf_errno.c

···
 #include <string.h>
 
 #include "libbpf.h"
+#include "libbpf_internal.h"
 
 /* make sure libbpf doesn't use kernel-only integer typedefs */
 #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
···
 int libbpf_strerror(int err, char *buf, size_t size)
 {
 	if (!buf || !size)
-		return -1;
+		return libbpf_err(-EINVAL);
 
 	err = err > 0 ? err : -err;
 
···
 
 		ret = strerror_r(err, buf, size);
 		buf[size - 1] = '\0';
-		return ret;
+		return libbpf_err_errno(ret);
 	}
 
 	if (err < __LIBBPF_ERRNO__END) {
···
 
 	snprintf(buf, size, "Unknown libbpf error %d", err);
 	buf[size - 1] = '\0';
-	return -1;
+	return libbpf_err(-ENOENT);
 }

tools/lib/bpf/libbpf_internal.h

···
 	return ret;
 }
 
+/* handle error for pointer-returning APIs, err is assumed to be < 0 always */
+static inline void *libbpf_err_ptr(int err)
+{
+	/* set errno on error, this doesn't break anything */
+	errno = -err;
+
+	if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS)
+		return NULL;
+
+	/* legacy: encode err as ptr */
+	return ERR_PTR(err);
+}
+
+/* handle pointer-returning APIs' error handling */
+static inline void *libbpf_ptr(void *ret)
+{
+	/* set errno on error, this doesn't break anything */
+	if (IS_ERR(ret))
+		errno = -PTR_ERR(ret);
+
+	if (libbpf_mode & LIBBPF_STRICT_CLEAN_PTRS)
+		return IS_ERR(ret) ? NULL : ret;
+
+	/* legacy: pass-through original pointer */
+	return ret;
+}
+
 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */

tools/lib/bpf/linker.c

···
 	int err;
 
 	if (!OPTS_VALID(opts, bpf_linker_opts))
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	if (elf_version(EV_CURRENT) == EV_NONE) {
 		pr_warn_elf("libelf initialization failed");
-		return NULL;
+		return errno = EINVAL, NULL;
 	}
 
 	linker = calloc(1, sizeof(*linker));
 	if (!linker)
-		return NULL;
+		return errno = ENOMEM, NULL;
 
 	linker->fd = -1;
 
···
 
 err_out:
 	bpf_linker__free(linker);
-	return NULL;
+	return errno = -err, NULL;
 }
 
 static struct dst_sec *add_dst_sec(struct bpf_linker *linker, const char *sec_name)
···
 	int err = 0;
 
 	if (!OPTS_VALID(opts, bpf_linker_file_opts))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (!linker->elf)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	err = err ?: linker_load_obj_file(linker, filename, opts, &obj);
 	err = err ?: linker_append_sec_data(linker, &obj);
···
 	if (obj.fd >= 0)
 		close(obj.fd);
 
-	return err;
+	return libbpf_err(err);
 }
 
 static bool is_dwarf_sec_name(const char *name)
···
 	int err, i;
 
 	if (!linker->elf)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	err = finalize_btf(linker);
 	if (err)
-		return err;
+		return libbpf_err(err);
 
 	/* Finalize strings */
 	strs_sz = strset__data_size(linker->strtab_strs);
···
 	if (elf_update(linker->elf, ELF_C_NULL) < 0) {
 		err = -errno;
 		pr_warn_elf("failed to finalize ELF layout");
-		return err;
+		return libbpf_err(err);
 	}
 
 	/* Write out final ELF contents */
 	if (elf_update(linker->elf, ELF_C_WRITE) < 0) {
 		err = -errno;
 		pr_warn_elf("failed to write ELF contents");
-		return err;
+		return libbpf_err(err);
 	}
 
 	elf_end(linker->elf);

tools/lib/bpf/netlink.c

···
 int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,
 			     const struct bpf_xdp_set_link_opts *opts)
 {
-	int old_fd = -1;
+	int old_fd = -1, ret;
 
 	if (!OPTS_VALID(opts, bpf_xdp_set_link_opts))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	if (OPTS_HAS(opts, old_fd)) {
 		old_fd = OPTS_GET(opts, old_fd, -1);
 		flags |= XDP_FLAGS_REPLACE;
 	}
 
-	return __bpf_set_link_xdp_fd_replace(ifindex, fd, old_fd, flags);
+	ret = __bpf_set_link_xdp_fd_replace(ifindex, fd, old_fd, flags);
+	return libbpf_err(ret);
 }
 
 int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 {
-	return __bpf_set_link_xdp_fd_replace(ifindex, fd, 0, flags);
+	int ret;
+
+	ret = __bpf_set_link_xdp_fd_replace(ifindex, fd, 0, flags);
+	return libbpf_err(ret);
 }
 
 static int __dump_link_nlmsg(struct nlmsghdr *nlh,
···
 	};
 
 	if (flags & ~XDP_FLAGS_MASK || !info_size)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	/* Check whether the single {HW,DRV,SKB} mode is set */
 	flags &= (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE);
 	mask = flags - 1;
 	if (flags && flags & mask)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	xdp_id.ifindex = ifindex;
 	xdp_id.flags = flags;
···
 		memset((void *) info + sz, 0, info_size - sz);
 	}
 
-	return ret;
+	return libbpf_err(ret);
 }
 
 static __u32 get_xdp_id(struct xdp_link_info *info, __u32 flags)
···
 	if (!ret)
 		*prog_id = get_xdp_id(&info, flags);
 
-	return ret;
+	return libbpf_err(ret);
 }
 
 typedef int (*qdisc_config_t)(struct nlmsghdr *nh, struct tcmsg *t,
···
 
 int bpf_tc_hook_create(struct bpf_tc_hook *hook)
 {
+	int ret;
+
 	if (!hook || !OPTS_VALID(hook, bpf_tc_hook) ||
 	    OPTS_GET(hook, ifindex, 0) <= 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
-	return tc_qdisc_create_excl(hook);
+	ret = tc_qdisc_create_excl(hook);
+	return libbpf_err(ret);
 }
 
 static int __bpf_tc_detach(const struct bpf_tc_hook *hook,
···
 {
 	if (!hook || !OPTS_VALID(hook, bpf_tc_hook) ||
 	    OPTS_GET(hook, ifindex, 0) <= 0)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	switch (OPTS_GET(hook, attach_point, 0)) {
 	case BPF_TC_INGRESS:
 	case BPF_TC_EGRESS:
-		return __bpf_tc_detach(hook, NULL, true);
+		return libbpf_err(__bpf_tc_detach(hook, NULL, true));
 	case BPF_TC_INGRESS | BPF_TC_EGRESS:
-		return tc_qdisc_delete(hook);
+		return libbpf_err(tc_qdisc_delete(hook));
 	case BPF_TC_CUSTOM:
-		return -EOPNOTSUPP;
+		return libbpf_err(-EOPNOTSUPP);
 	default:
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 }
 
···
 	if (!hook || !opts ||
 	    !OPTS_VALID(hook, bpf_tc_hook) ||
 	    !OPTS_VALID(opts, bpf_tc_opts))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	ifindex      = OPTS_GET(hook, ifindex, 0);
 	parent       = OPTS_GET(hook, parent, 0);
···
 	flags        = OPTS_GET(opts, flags, 0);
 
 	if (ifindex <= 0 || !prog_fd || prog_id)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (priority > UINT16_MAX)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (flags & ~BPF_TC_F_REPLACE)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	flags = (flags & BPF_TC_F_REPLACE) ? NLM_F_REPLACE : NLM_F_EXCL;
 	protocol = ETH_P_ALL;
···
 
 	ret = tc_get_tcm_parent(attach_point, &parent);
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	req.tc.tcm_parent = parent;
 
 	ret = nlattr_add(&req.nh, sizeof(req), TCA_KIND, "bpf", sizeof("bpf"));
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	nla = nlattr_begin_nested(&req.nh, sizeof(req), TCA_OPTIONS);
 	if (!nla)
-		return -EMSGSIZE;
+		return libbpf_err(-EMSGSIZE);
 	ret = tc_add_fd_and_name(&req.nh, sizeof(req), prog_fd);
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	bpf_flags = TCA_BPF_FLAG_ACT_DIRECT;
 	ret = nlattr_add(&req.nh, sizeof(req), TCA_BPF_FLAGS, &bpf_flags,
 			 sizeof(bpf_flags));
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	nlattr_end_nested(&req.nh, nla);
 
 	info.opts = opts;
 
 	ret = libbpf_netlink_send_recv(&req.nh, get_tc_info, NULL, &info);
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	if (!info.processed)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 	return ret;
 }
 
···
 int bpf_tc_detach(const struct bpf_tc_hook *hook,
 		  const struct bpf_tc_opts *opts)
 {
-	return !opts ? -EINVAL : __bpf_tc_detach(hook, opts, false);
+	int ret;
+
+	if (!opts)
+		return libbpf_err(-EINVAL);
+
+	ret = __bpf_tc_detach(hook, opts, false);
+	return libbpf_err(ret);
 }
 
 int bpf_tc_query(const struct bpf_tc_hook *hook, struct bpf_tc_opts *opts)
···
 	if (!hook || !opts ||
 	    !OPTS_VALID(hook, bpf_tc_hook) ||
 	    !OPTS_VALID(opts, bpf_tc_opts))
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	ifindex      = OPTS_GET(hook, ifindex, 0);
 	parent       = OPTS_GET(hook, parent, 0);
···
 
 	if (ifindex <= 0 || flags || prog_fd || prog_id ||
 	    !handle || !priority)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	if (priority > UINT16_MAX)
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 
 	protocol = ETH_P_ALL;
 
···
 
 	ret = tc_get_tcm_parent(attach_point, &parent);
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	req.tc.tcm_parent = parent;
 
 	ret = nlattr_add(&req.nh, sizeof(req), TCA_KIND, "bpf", sizeof("bpf"));
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 
 	info.opts = opts;
 
 	ret = libbpf_netlink_send_recv(&req.nh, get_tc_info, NULL, &info);
 	if (ret < 0)
-		return ret;
+		return libbpf_err(ret);
 	if (!info.processed)
-		return -ENOENT;
+		return libbpf_err(-ENOENT);
 	return ret;
 }

tools/lib/bpf/ringbuf.c

···
 		err = -errno;
 		pr_warn("ringbuf: failed to get map info for fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 
 	if (info.type != BPF_MAP_TYPE_RINGBUF) {
 		pr_warn("ringbuf: map fd=%d is not BPF_MAP_TYPE_RINGBUF\n",
 			map_fd);
-		return -EINVAL;
+		return libbpf_err(-EINVAL);
 	}
 
 	tmp = libbpf_reallocarray(rb->rings, rb->ring_cnt + 1, sizeof(*rb->rings));
 	if (!tmp)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 	rb->rings = tmp;
 
 	tmp = libbpf_reallocarray(rb->events, rb->ring_cnt + 1, sizeof(*rb->events));
 	if (!tmp)
-		return -ENOMEM;
+		return libbpf_err(-ENOMEM);
 	rb->events = tmp;
 
 	r = &rb->rings[rb->ring_cnt];
···
 		err = -errno;
 		pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 	r->consumer_pos = tmp;
 
···
 		ringbuf_unmap_ring(rb, r);
 		pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 	r->producer_pos = tmp;
 	r->data = tmp + rb->page_size;
···
 		ringbuf_unmap_ring(rb, r);
 		pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n",
 			map_fd, err);
-		return err;
+		return libbpf_err(err);
 	}
 
 	rb->ring_cnt++;
···
 	int err;
 
 	if (!OPTS_VALID(opts, ring_buffer_opts))
-		return NULL;
+		return errno = EINVAL, NULL;
 
 	rb = calloc(1, sizeof(*rb));
 	if (!rb)
-		return NULL;
+		return errno = ENOMEM, NULL;
 
 	rb->page_size = getpagesize();
 
···
 
 err_out:
 	ring_buffer__free(rb);
-	return NULL;
+	return errno = -err, NULL;
 }
 
 static inline int roundup_len(__u32 len)
···
 
 		err = ringbuf_process_ring(ring);
 		if (err < 0)
-			return err;
+			return libbpf_err(err);
 		res += err;
 	}
 	if (res > INT_MAX)
···
 
 	cnt = epoll_wait(rb->epoll_fd, rb->events, rb->ring_cnt, timeout_ms);
 	if (cnt < 0)
-		return -errno;
+		return libbpf_err(-errno);
 
 	for (i = 0; i < cnt; i++) {
 		__u32 ring_id = rb->events[i].data.fd;
···
 
 		err = ringbuf_process_ring(ring);
 		if (err < 0)
-			return err;
+			return libbpf_err(err);
 		res += err;
 	}
 	if (res > INT_MAX)