On Thu, Sep 14, 2023 at 4:12 PM Martin Kelly
<martin.kelly@xxxxxxxxxxxxxxx> wrote:
>
> Add a new function ring_buffer__ring, which exposes struct ring * to the
> user, representing a single ringbuffer.
>
> Signed-off-by: Martin Kelly <martin.kelly@xxxxxxxxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.h | 14 ++++++++++++++
> tools/lib/bpf/libbpf.map | 1 +
> tools/lib/bpf/ringbuf.c | 8 ++++++++
> 3 files changed, 23 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 0e52621cba43..2d6c39e20863 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -1229,6 +1229,7 @@ LIBBPF_API int bpf_tc_query(const struct bpf_tc_hook *hook,
>
> /* Ring buffer APIs */
> struct ring_buffer;
> +struct ring;
> struct user_ring_buffer;
>
> typedef int (*ring_buffer_sample_fn)(void *ctx, void *data, size_t size);
> @@ -1249,6 +1250,19 @@ 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(const struct ring_buffer *rb);
>
> +/**
> + * @brief **ring_buffer__ring()** returns the ring object inside a given
> + * ringbuffer.
s/ringbuffer/ring buffer manager/
and I'd also add ", representing single BPF_MAP_TYPE_RINGBUF map instance"
> + *
> + * @param rb A ringbuffer object.
"ring buffer manager"?
> + * @param idx An index into the rings contained within the ringbuffer object.
> + * The index is 0-based and corresponds to the order in which ring_buffer__add
> + * was called.
> + * @return A ring object on success; NULL and errno set if the index is invalid.
> + */
> +LIBBPF_API struct ring *ring_buffer__ring(struct ring_buffer *rb,
> + unsigned int idx);
> +
> struct user_ring_buffer_opts {
> size_t sz; /* size of this struct, for forward/backward compatibility */
> };
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 57712321490f..7a7370c2bc25 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -400,4 +400,5 @@ LIBBPF_1.3.0 {
> bpf_program__attach_netfilter;
> bpf_program__attach_tcx;
> bpf_program__attach_uprobe_multi;
> + ring_buffer__ring;
> } LIBBPF_1.2.0;
> diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
> index c2c79e10cfea..2857df0f2d03 100644
> --- a/tools/lib/bpf/ringbuf.c
> +++ b/tools/lib/bpf/ringbuf.c
> @@ -328,6 +328,14 @@ int ring_buffer__epoll_fd(const struct ring_buffer *rb)
> return rb->epoll_fd;
> }
>
> +struct ring *ring_buffer__ring(struct ring_buffer *rb, unsigned int idx)
> +{
> + if (idx >= rb->ring_cnt)
> + return errno = ERANGE, NULL;
> +
> + return rb->rings[idx];
> +}
> +
> static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
> {
> if (rb->consumer_pos) {
> --
> 2.34.1
>
