On Wed, 23 Jan 2019 11:54:41 +0100
Daniel Borkmann <dan...@iogearbox.net> wrote:
> On 01/21/2019 10:10 AM, Maciej Fijalkowski wrote:
> > XDP samples are mostly cooperating with eBPF maps through their file
> > descriptors. In case of a eBPF program that contains multiple maps it
> > might be tiresome to iterate through them and call bpf_map__fd for each
> > one. Add a helper mostly based on bpf_object__find_map_by_name, but
> > instead of returning the struct bpf_map pointer, return map fd.
> >
> > Bump libbpf ABI version to 0.0.2.
> >
> > Suggested-by: Jakub Kicinski <jakub.kicin...@netronome.com>
> > Signed-off-by: Maciej Fijalkowski <maciejromanfijalkow...@gmail.com>
> > Reviewed-by: Jakub Kicinski <jakub.kicin...@netronome.com>
> > ---
> > tools/lib/bpf/libbpf.c | 12 ++++++++++++
> > tools/lib/bpf/libbpf.h | 3 +++
> > tools/lib/bpf/libbpf.map | 4 ++++
> > 3 files changed, 19 insertions(+)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index 169e347c76f6..dc838bea403f 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -2840,6 +2840,18 @@ bpf_object__find_map_by_name(struct bpf_object *obj,
> > const char *name)
> > return NULL;
> > }
>
> Application could just do: bpf_map__fd(bpf_object__find_map_by_name(...)) or
> bpf_object__find_map_by_name(...)->fd as both are exposed via library, though
> I guess it may be okay to have a helper for it as it feels this might be
> needed
> in many cases.
>
> > +int
> > +bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
> > +{
> > + struct bpf_map *pos;
> > +
> > + bpf_map__for_each(pos, obj) {
> > + if (pos->name && !strcmp(pos->name, name))
> > + return bpf_map__fd(pos);
> > + }
> > + return -ENOENT;
>
> Can we instead just do:
>
> int
> bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name)
> {
> return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
> }
>
Yes of course, I will send v3 once we figure out what's the best way to supply
the prog section name for xdp_redirect_cpu.
> > +}
> > +
> > struct bpf_map *
> > bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
> > {
> > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> > index 5f68d7b75215..7f10d36abdde 100644
> > --- a/tools/lib/bpf/libbpf.h
> > +++ b/tools/lib/bpf/libbpf.h
> > @@ -264,6 +264,9 @@ struct bpf_map;
> > LIBBPF_API struct bpf_map *
> > bpf_object__find_map_by_name(struct bpf_object *obj, const char *name);
> >
> > +LIBBPF_API int
> > +bpf_object__find_map_fd_by_name(struct bpf_object *obj, const char *name);
> > +
> > /*
> > * Get bpf_map through the offset of corresponding struct bpf_map_def
> > * in the BPF object file.
> > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> > index cd02cd4e2cc3..7c59e4f64082 100644
> > --- a/tools/lib/bpf/libbpf.map
> > +++ b/tools/lib/bpf/libbpf.map
> > @@ -124,3 +124,7 @@ LIBBPF_0.0.1 {
> > local:
> > *;
> > };
> > +LIBBPF_0.0.2 {
> > + global:
> > + bpf_object__find_map_fd_by_name;
> > +} LIBBPF_0.0.1;
> >
>
