* [PATCH bpf-next] libbpf: fix bail out from 'ringbuf_process_ring()' on error
@ 2021-03-25 15:01 Pedro Tammela
2021-03-26 4:31 ` Andrii Nakryiko
0 siblings, 1 reply; 2+ messages in thread
From: Pedro Tammela @ 2021-03-25 15:01 UTC (permalink / raw)
Cc: Pedro Tammela, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, netdev, bpf, linux-kernel
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@mojatatu.com>
---
tools/lib/bpf/ringbuf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH bpf-next] libbpf: fix bail out from 'ringbuf_process_ring()' on error
2021-03-25 15:01 [PATCH bpf-next] libbpf: fix bail out from 'ringbuf_process_ring()' on error Pedro Tammela
@ 2021-03-26 4:31 ` Andrii Nakryiko
0 siblings, 0 replies; 2+ messages in thread
From: Andrii Nakryiko @ 2021-03-26 4:31 UTC (permalink / raw)
To: Pedro Tammela
Cc: Pedro Tammela, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Networking, bpf, open list
On Thu, Mar 25, 2021 at 8:02 AM Pedro Tammela <pctammela@gmail.com> 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@mojatatu.com>
> ---
> 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
>
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