On Thu, Sep 14, 2023 at 4:12 PM Martin Kelly
<martin.kelly@xxxxxxxxxxxxxxx> wrote:
>
> Add ring__consume to consume a single ringbuffer, analogous to
> ring_buffer__consume.
>
> Signed-off-by: Martin Kelly <martin.kelly@xxxxxxxxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.h | 10 ++++++++++
> tools/lib/bpf/libbpf.map | 1 +
> tools/lib/bpf/ringbuf.c | 13 +++++++++++++
> 3 files changed, 24 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index d2a237086c2c..861f8b6795e9 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -1307,6 +1307,16 @@ LIBBPF_API size_t ring__size(const struct ring *r);
> */
> LIBBPF_API int ring__map_fd(const struct ring *r);
>
> +/**
> + * @brief **ring__consume()** consumes available ringbuffer data without event
> + * polling.
> + *
> + * @param r A ring object.
> + * @return The number of records consumed (or INT_MAX, whichever is less), or
> + * a negative number if any of the callbacks return an error.
> + */
> +LIBBPF_API int ring__consume(struct ring *r);
> +
> 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 13800b73c343..4b5124bb0e1a 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -402,6 +402,7 @@ LIBBPF_1.3.0 {
> bpf_program__attach_uprobe_multi;
> ring_buffer__ring;
> ring__avail_data_size;
> + ring__consume;
> ring__consumer_pos;
> ring__map_fd;
> ring__producer_pos;
> diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
> index 2dba2836d85b..b7ef003366d3 100644
> --- a/tools/lib/bpf/ringbuf.c
> +++ b/tools/lib/bpf/ringbuf.c
> @@ -365,6 +365,19 @@ int ring__map_fd(const struct ring *r)
> return r->map_fd;
> }
>
> +int ring__consume(struct ring *r)
> +{
> + int64_t res;
> +
> + res = ringbuf_process_ring(r);
> + if (res < 0)
> + res = libbpf_err(res);
it's a bit confusing to have libbpf_err() not within some return.
Let's do `return libbpf_err(res);` here as the only error path?
> + else if (res > INT_MAX)
> + res = INT_MAX;
> +
> + return res;
and here we can have `return res > INT_MAX ? INT_MAX : res;`
> +}
> +
> static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb)
> {
> if (rb->consumer_pos) {
> --
> 2.34.1
>
