Re: [PATCH bpf-next v4 03/16] bpf: Add verifier diagnostic event log
Eduard Zingerman <[email protected]>
| Newsgroups | org.kernel.vger.bpf |
|---|---|
| Message-ID | <[email protected]> |
On Thu, 2026-08-13 at 01:33 +0200, Kumar Kartikeya Dwivedi wrote:
...
> kernel/bpf/diagnostics.c | 108 +++++++++++++++++++++++++++++++++++++++
> kernel/bpf/diagnostics.h | 3 ++
> kernel/bpf/verifier.c | 21 ++++++++
> 3 files changed, 132 insertions(+)
>
> diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
> index 77dcffb9adee..0e0aa3a7106c 100644
> --- a/kernel/bpf/diagnostics.c
> +++ b/kernel/bpf/diagnostics.c
> @@ -34,8 +34,24 @@
> #define BPF_DIAG_REG_TMP_LEN 192
> #define BPF_DIAG_FMT_CHUNK_SIZE 1024
> #define BPF_DIAG_FMT_BUF_SIZE 256
> +#define BPF_DIAG_EVENT_LOG_MAX_SIZE (1U << 20)
Q: did you observe the drops in practice?
I'm curious what would be a practical limit here.
As it stands the events buffer is 7K entries, seem to be low.
...
> +void bpf_diag_event_log_reset(struct bpf_verifier_env *env, u32 pos)
> +{
> + struct bpf_diag *diag = env->diag;
> + struct bpf_diag_log *log;
> + u32 end;
> +
> + if (!diag)
> + return;
> +
> + log = &diag->log;
> + end = log->cnt;
> + if (WARN_ON_ONCE(pos > end))
> + pos = end;
> +
> + log->cnt = pos;
Should this reset 'dropped' as well? 'capped'?
If not, do we need an exact count for 'dropped'?
> +}
> +
...