2020-12-14 20:49:52

by Daniel Borkmann

Subject: Re: [PATCH bpf-next v2] libbpf: Expose libbpf ringbufer epoll_fd

On 12/14/20 12:38 PM, Brendan Jackman wrote:
> This provides a convenient perf ringbuf -> libbpf ringbuf migration
> path for users of external polling systems. It is analogous to
> perf_buffer__epoll_fd.
>
> Signed-off-by: Brendan Jackman <[email protected]>
> ---
> Difference from v1: Added entry to libbpf.map.
>
> tools/lib/bpf/libbpf.h | 1 +
> tools/lib/bpf/libbpf.map | 1 +
> tools/lib/bpf/ringbuf.c | 6 ++++++
> 3 files changed, 8 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 6909ee81113a..cde07f64771e 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -536,6 +536,7 @@ LIBBPF_API int ring_buffer__add(struct ring_buffer *rb, int map_fd,
> ring_buffer_sample_fn sample_cb, void *ctx);
> LIBBPF_API int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms);
> LIBBPF_API int ring_buffer__consume(struct ring_buffer *rb);
> +LIBBPF_API int ring_buffer__epoll_fd(struct ring_buffer *rb);
>
> /* Perf buffer APIs */
> struct perf_buffer;
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 7c4126542e2b..7be850271be6 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -348,4 +348,5 @@ LIBBPF_0.3.0 {
> btf__new_split;
> xsk_setup_xdp_prog;
> xsk_socket__update_xskmap;
> + ring_buffer__epoll_fd;

Fyi, this had a whitespace issue, Andrii fixed it up while applying.

> } LIBBPF_0.2.0;
> diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
> index 5c6522c89af1..45a36648b403 100644
> --- a/tools/lib/bpf/ringbuf.c
> +++ b/tools/lib/bpf/ringbuf.c
> @@ -282,3 +282,9 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms)
> }
> return cnt < 0 ? -errno : res;
> }
> +
> +/* Get an fd that can be used to sleep until data is available in the ring(s) */
> +int ring_buffer__epoll_fd(struct ring_buffer *rb)
> +{
> + return rb->epoll_fd;
> +}
>
> base-commit: b4fe9fec51ef48011f11c2da4099f0b530449c92
> --
> 2.29.2.576.ga3fc446d84-goog
>

2020-12-15 10:31:08

by Brendan Jackman

Subject: Re: [PATCH bpf-next v2] libbpf: Expose libbpf ringbufer epoll_fd

On Mon, 14 Dec 2020 at 21:46, Daniel Borkmann <[email protected]> wrote:
>
> On 12/14/20 12:38 PM, Brendan Jackman wrote:
[...]
> > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> > index 7c4126542e2b..7be850271be6 100644
> > --- a/tools/lib/bpf/libbpf.map
> > +++ b/tools/lib/bpf/libbpf.map
> > @@ -348,4 +348,5 @@ LIBBPF_0.3.0 {
> > btf__new_split;
> > xsk_setup_xdp_prog;
> > xsk_socket__update_xskmap;
> > + ring_buffer__epoll_fd;
>
> Fyi, this had a whitespace issue, Andrii fixed it up while applying.

Sorry about that.