libbpf: Update a bpf_link with another struct_ops.

Introduce bpf_link__update_map(), which allows to atomically update
underlying struct_ops implementation for given struct_ops BPF link.

Also add old_map_fd to struct bpf_link_update_opts to handle
BPF_F_REPLACE feature.

Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Link: https://lore.kernel.org/r/20230323032405.3735486-7-kuifeng@meta.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Kui-Feng Lee
2023-03-22 20:24:03 -07:00
committed by Andrii Nakryiko
parent 055cbdcc9f
commit e51cdaaca0
5 changed files with 46 additions and 2 deletions

View File

@@ -794,11 +794,17 @@ int bpf_link_update(int link_fd, int new_prog_fd,
if (!OPTS_VALID(opts, bpf_link_update_opts))
return libbpf_err(-EINVAL);
if (OPTS_GET(opts, old_prog_fd, 0) && OPTS_GET(opts, old_map_fd, 0))
return libbpf_err(-EINVAL);
memset(&attr, 0, attr_sz);
attr.link_update.link_fd = link_fd;
attr.link_update.new_prog_fd = new_prog_fd;
attr.link_update.flags = OPTS_GET(opts, flags, 0);
attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0);
if (OPTS_GET(opts, old_prog_fd, 0))
attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0);
else if (OPTS_GET(opts, old_map_fd, 0))
attr.link_update.old_map_fd = OPTS_GET(opts, old_map_fd, 0);
ret = sys_bpf(BPF_LINK_UPDATE, &attr, attr_sz);
return libbpf_err_errno(ret);