Andrii Nakryiko c016b68edc libbpf: Add bpf_link pinning/unpinning
With bpf_link abstraction supported by kernel explicitly, add
pinning/unpinning API for links. Also allow to create (open) bpf_link from BPF
FS file.

This API allows to have an "ephemeral" FD-based BPF links (like raw tracepoint
or fexit/freplace attachments) surviving user process exit, by pinning them in
a BPF FS, which is an important use case for long-running BPF programs.

As part of this, expose underlying FD for bpf_link. While legacy bpf_link's
might not have a FD associated with them (which will be expressed as
a bpf_link with fd=-1), kernel's abstraction is based around FD-based usage,
so match it closely. This, subsequently, allows to have a generic
pinning/unpinning API for generalized bpf_link. For some types of bpf_links
kernel might not support pinning, in which case bpf_link__pin() will return
error.

With FD being part of generic bpf_link, also get rid of bpf_link_fd in favor
of using vanialla bpf_link.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200303043159.323675-3-andriin@fb.com
2020-03-02 22:06:27 -08:00
..
2020-01-14 12:40:33 -03:00
2019-10-29 12:04:18 +00:00
2019-10-13 09:38:27 -04:00