Introduce a new API to consume items from a ring buffer, limited to a specified amount, and return to the caller the actual number of items consumed. Link: https://lore.kernel.org/lkml/20240310154726.734289-1-andrea.righi@xxxxxxxxxxxxx/T Signed-off-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx> --- tools/lib/bpf/libbpf.h | 13 +++++++++++++ tools/lib/bpf/libbpf.map | 2 ++ tools/lib/bpf/ringbuf.c | 35 +++++++++++++++++++++++++++++++++-- 3 files changed, 48 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index f88ab50c0229..85161889efd4 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -1293,6 +1293,8 @@ 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__consume_max(struct ring_buffer *rb, + size_t max_items); LIBBPF_API int ring_buffer__epoll_fd(const struct ring_buffer *rb); /** @@ -1367,6 +1369,17 @@ LIBBPF_API int ring__map_fd(const struct ring *r); */ LIBBPF_API int ring__consume(struct ring *r); +/** + * @brief **ring__consume_max()** consumes up to a certain amount of items from + * a ringbuffer without event polling. + * + * @param r A ringbuffer object. + * @param max_items Maximum amount of items to consume. + * @return The number of items consumed (or max_items, whichever is less), or a + * negative number if any of the callbacks return an error. + */ +LIBBPF_API int ring__consume_max(struct ring *r, size_t max_items); + 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 51732ecb1385..bb3ed905119d 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -415,4 +415,6 @@ LIBBPF_1.4.0 { bpf_token_create; btf__new_split; btf_ext__raw_data; + ring__consume_max; + ring_buffer__consume_max; } LIBBPF_1.3.0; diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index 81df535040d1..c8123e326b1a 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -281,6 +281,32 @@ static int64_t ringbuf_process_ring(struct ring *r, int64_t max_items) return cnt; } +/* Consume available ring buffer(s) data without event polling up to max_items. + * + * Returns number of records consumed across all registered ring buffers (or + * max_items, whichever is less), or negative number if any of the callbacks + * return error. + */ +int ring_buffer__consume_max(struct ring_buffer *rb, size_t max_items) +{ + int64_t err, res = 0; + int i; + + for (i = 0; i < rb->ring_cnt; i++) { + struct ring *ring = rb->rings[i]; + + err = ringbuf_process_ring(ring, max_items); + if (err < 0) + return libbpf_err(err); + res += err; + max_items -= err; + + if (!max_items) + break; + } + return res; +} + /* Consume available ring buffer(s) data without event polling. * Returns number of records consumed across all registered ring buffers (or * INT_MAX, whichever is less), or negative number if any of the callbacks @@ -376,17 +402,22 @@ int ring__map_fd(const struct ring *r) return r->map_fd; } -int ring__consume(struct ring *r) +int ring__consume_max(struct ring *r, size_t max_items) { int64_t res; - res = ringbuf_process_ring(r, INT_MAX); + res = ringbuf_process_ring(r, max_items); if (res < 0) return libbpf_err(res); return res; } +int ring__consume(struct ring *r) +{ + return ring__consume_max(r, INT_MAX); +} + static void user_ringbuf_unmap_ring(struct user_ring_buffer *rb) { if (rb->consumer_pos) { -- 2.43.0
