Re: [PATCH bpf-next] libbpf: fix bail out from 'ringbuf_process_ring()' on error

[Andrii Nakryiko]

On Thu, Mar 25, 2021 at 8:02 AM Pedro Tammela <pctammela@xxxxxxxxx> wrote:
>
> The current code bails out with negative and positive returns.
> If the callback returns a positive return code, 'ring_buffer__consume()'
> and 'ring_buffer__poll()' will return a spurious number of records
> consumed, but mostly important will continue the processing loop.
>
> This patch makes positive returns from the callback a no-op.
>
> Signed-off-by: Pedro Tammela <pctammela@xxxxxxxxxxxx>
> ---
>  tools/lib/bpf/ringbuf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>

Thanks. Applied to bpf tree and added:

Fixes: bf99c936f947 ("libbpf: Add BPF ring buffer support")


> diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
> index 8caaafe7e312..e7a8d847161f 100644
> --- a/tools/lib/bpf/ringbuf.c
> +++ b/tools/lib/bpf/ringbuf.c
> @@ -227,7 +227,7 @@ static int ringbuf_process_ring(struct ring* r)
>                         if ((len & BPF_RINGBUF_DISCARD_BIT) == 0) {
>                                 sample = (void *)len_ptr + BPF_RINGBUF_HDR_SZ;
>                                 err = r->sample_cb(r->ctx, sample, len);
> -                               if (err) {
> +                               if (err < 0) {
>                                         /* update consumer pos and bail out */
>                                         smp_store_release(r->consumer_pos,
>                                                           cons_pos);
> --
> 2.25.1
>