On Fri, Mar 20, 2026 at 04:41:55PM +0800, Menglong Dong wrote:
> Add the testing to access the bpf_ringbuf with the map pointer.
> "consumer_pos" and "producer_pos" is accessed in this testing. We reserve
> 128 bytes in the ringbuf to test the producer_pos, which should be
> "128 + 8", and the "8" is BPF_RINGBUF_HDR_SZ.
>
> It will be helpful if we want to evaluate the usage of the ringbuf in bpf
> prog with the consumer and producer position.
>
> Signed-off-by: Menglong Dong <[email protected]>
> ---
> .../testing/selftests/bpf/progs/map_ptr_kern.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/map_ptr_kern.c
> b/tools/testing/selftests/bpf/progs/map_ptr_kern.c
> index efaf622c28dd..c3fa57ec430b 100644
> --- a/tools/testing/selftests/bpf/progs/map_ptr_kern.c
> +++ b/tools/testing/selftests/bpf/progs/map_ptr_kern.c
> @@ -647,21 +647,39 @@ static inline int check_devmap_hash(void)
> return 1;
> }
>
> +struct bpf_ringbuf {
> + unsigned long consumer_pos;
> + unsigned long producer_pos;
> +} __attribute__((preserve_access_index));
> +
> struct bpf_ringbuf_map {
> struct bpf_map map;
> + struct bpf_ringbuf *rb;
> } __attribute__((preserve_access_index));
>
> struct {
> __uint(type, BPF_MAP_TYPE_RINGBUF);
> + __uint(max_entries, 1 << 10);
do you need to set max_entries? there's already check below
making sure it's 4096
jirka
> } m_ringbuf SEC(".maps");
>
> static inline int check_ringbuf(void)
> {
> struct bpf_ringbuf_map *ringbuf = (struct bpf_ringbuf_map *)&m_ringbuf;
> struct bpf_map *map = (struct bpf_map *)&m_ringbuf;
> + struct bpf_ringbuf *rb;
> + void *ptr;
>
> VERIFY(check(&ringbuf->map, map, 0, 0, page_size));
>
> + ptr = bpf_ringbuf_reserve(&m_ringbuf, 128, 0);
> + VERIFY(ptr);
> +
> + bpf_ringbuf_discard(ptr, 0);
> + rb = ringbuf->rb;
> + VERIFY(rb);
> + VERIFY(rb->consumer_pos == 0);
> + VERIFY(rb->producer_pos == 128 + 8);
> +
> return 1;
> }
>
> --
> 2.53.0
>
