Introduce ring__consume_n() and ring_buffer__consume_n() API to partially consume items from one (or more) ringbuffer(s).
This can be useful, for example, to consume just a single item or when we need to copy multiple items to a limited user-space buffer from the ringbuffer callback.
Practical example (where this API can be used): https://github.com/sched-ext/scx/blob/b7c06b9ed9f72cad83c31e39e9c4e2cfd8683a...
See also: https://lore.kernel.org/lkml/20240310154726.734289-1-andrea.righi@canonical....
v4: - add a selftest to test the new API - open a new 1.5.0 cycle
v3: - rename ring__consume_max() -> ring__consume_n() and ring_buffer__consume_max() -> ring_buffer__consume_n() - add new API to a new 1.5.0 cycle - fixed minor nits / comments
v2: - introduce a new API instead of changing the callback's retcode behavior
Andrea Righi (4): libbpf: Start v1.5 development cycle libbpf: ringbuf: allow to consume up to a certain amount of items libbpf: Add ring__consume_n / ring_buffer__consume_n selftests/bpf: Add tests for ring__consume_n and ring_buffer__consume_n
tools/lib/bpf/libbpf.h | 12 +++++ tools/lib/bpf/libbpf.map | 6 +++ tools/lib/bpf/libbpf_version.h | 2 +- tools/lib/bpf/ringbuf.c | 59 ++++++++++++++++++++---- tools/testing/selftests/bpf/prog_tests/ringbuf.c | 8 ++++ 5 files changed, 76 insertions(+), 11 deletions(-)