On Fri, Jun 28, 2019 at 9:02 AM Stanislav Fomichev <sdf@xxxxxxxxxxx> wrote:
>
> On 06/27, Andrii Nakryiko wrote:
> > bpf_link is and abstraction of an association of a BPF program and one
> > of many possible BPF attachment points (hooks). This allows to have
> > uniform interface for detaching BPF programs regardless of the nature of
> > link and how it was created. Details of creation and setting up of
> > a specific bpf_link is handled by corresponding attachment methods
> > (bpf_program__attach_xxx) added in subsequent commits. Once successfully
> > created, bpf_link has to be eventually destroyed with
> > bpf_link__destroy(), at which point BPF program is disassociated from
> > a hook and all the relevant resources are freed.
> >
> > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
> > ---
> > tools/lib/bpf/libbpf.c | 17 +++++++++++++++++
> > tools/lib/bpf/libbpf.h | 4 ++++
> > tools/lib/bpf/libbpf.map | 3 ++-
> > 3 files changed, 23 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index 6e6ebef11ba3..455795e6f8af 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -3941,6 +3941,23 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
> > return 0;
> > }
> >
> > +struct bpf_link {
> Maybe call it bpf_attachment? You call the bpf_program__attach_to_blah
> and you get an attachment?
I wanted to keep it as short as possible, bpf_attachment is way too
long (it's also why as an alternative I've proposed bpf_assoc, not
bpf_association, but bpf_attach isn't great shortening).
>
> > + int (*destroy)(struct bpf_link *link);
> > +};
> > +
> > +int bpf_link__destroy(struct bpf_link *link)
> > +{
> > + int err;
> > +
> > + if (!link)
> > + return 0;
> > +
> > + err = link->destroy(link);
> > + free(link);
> > +
> > + return err;
> > +}
> > +
> > enum bpf_perf_event_ret
> > bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
> > void **copy_mem, size_t *copy_size,
> > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> > index d639f47e3110..5082a5ebb0c2 100644
> > --- a/tools/lib/bpf/libbpf.h
> > +++ b/tools/lib/bpf/libbpf.h
> > @@ -165,6 +165,10 @@ LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path);
> > LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path);
> > LIBBPF_API void bpf_program__unload(struct bpf_program *prog);
> >
> > +struct bpf_link;
> > +
> > +LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
> > +
> > struct bpf_insn;
> >
> > /*
> > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> > index 2c6d835620d2..3cde850fc8da 100644
> > --- a/tools/lib/bpf/libbpf.map
> > +++ b/tools/lib/bpf/libbpf.map
> > @@ -167,10 +167,11 @@ LIBBPF_0.0.3 {
> >
> > LIBBPF_0.0.4 {
> > global:
> > + bpf_link__destroy;
> > + bpf_object__load_xattr;
> > btf_dump__dump_type;
> > btf_dump__free;
> > btf_dump__new;
> > btf__parse_elf;
> > - bpf_object__load_xattr;
> > libbpf_num_possible_cpus;
> > } LIBBPF_0.0.3;
> > --
> > 2.17.1
> >
