Commit 97c8f9dd authored by Roberto Sassu's avatar Roberto Sassu Committed by Andrii Nakryiko
Browse files

libbpf: Introduce bpf_link_get_fd_by_id_opts() 



Introduce bpf_link_get_fd_by_id_opts(), for symmetry with
bpf_map_get_fd_by_id_opts(), to let the caller pass the newly introduced
data structure bpf_get_fd_by_id_opts. Keep the existing
bpf_link_get_fd_by_id(), and call bpf_link_get_fd_by_id_opts() with NULL as
opts argument, to prevent setting open_flags.

Currently, the kernel does not support non-zero open_flags for
bpf_link_get_fd_by_id_opts(), and a call with them will result in an error
returned by the bpf() system call. The caller should always pass zero
open_flags.

Signed-off-by: default avatarRoberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221006110736.84253-6-roberto.sassu@huaweicloud.com
parent 2ce7cbf2

tools/lib/bpf/bpf.c

+11 −1
Original line number Diff line number Diff line
@@ -1004,19 +1004,29 @@ int bpf_btf_get_fd_by_id(__u32 id) 
	return bpf_btf_get_fd_by_id_opts(id, NULL);

}



int bpf_link_get_fd_by_id(__u32 id)

int bpf_link_get_fd_by_id_opts(__u32 id,

			       const struct bpf_get_fd_by_id_opts *opts)

{

	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);

	union bpf_attr attr;

	int fd;



	if (!OPTS_VALID(opts, bpf_get_fd_by_id_opts))

		return libbpf_err(-EINVAL);



	memset(&attr, 0, attr_sz);

	attr.link_id = id;

	attr.open_flags = OPTS_GET(opts, open_flags, 0);



	fd = sys_bpf_fd(BPF_LINK_GET_FD_BY_ID, &attr, attr_sz);

	return libbpf_err_errno(fd);

}



int bpf_link_get_fd_by_id(__u32 id)

{

	return bpf_link_get_fd_by_id_opts(id, NULL);

}



int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)

{

	const size_t attr_sz = offsetofend(union bpf_attr, info);

tools/lib/bpf/bpf.h

+2 −0
Original line number Diff line number Diff line
@@ -383,6 +383,8 @@ LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id); 
LIBBPF_API int bpf_btf_get_fd_by_id_opts(__u32 id,

				const struct bpf_get_fd_by_id_opts *opts);

LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_link_get_fd_by_id_opts(__u32 id,

				const struct bpf_get_fd_by_id_opts *opts);

LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);



struct bpf_prog_query_opts {

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -372,6 +372,7 @@ LIBBPF_1.0.0 { 
LIBBPF_1.1.0 {

	global:

		bpf_btf_get_fd_by_id_opts;

		bpf_link_get_fd_by_id_opts;

		bpf_map_get_fd_by_id_opts;

		bpf_prog_get_fd_by_id_opts;

		user_ring_buffer__discard;