From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Feng zhou <zhoufeng.zf@bytedance.com>
Cc: Networking <netdev@vger.kernel.org>,
Stephen Hemminger <stephen@networkplumber.org>,
kuznet@ms2.inr.ac.ru, duanxiongchun@bytedance.com,
Dongdong Wang <wangdongdong.6@bytedance.com>,
chenzhuowen.simon@bytedance.com
Subject: Re: [PATCH] lib/bpf: Fix btf_load error lead to enable debug log
Date: Fri, 30 Jul 2021 11:40:28 -0700 [thread overview]
Message-ID: <CAEf4BzY8_n9Yvd0Tpveca5-YRQYpqLgZHshHTWVUNOrAzUJfWw@mail.gmail.com> (raw)
In-Reply-To: <20210729045516.7373-1-zhoufeng.zf@bytedance.com>
On Wed, Jul 28, 2021 at 9:55 PM Feng zhou <zhoufeng.zf@bytedance.com> wrote:
>
> From: Feng Zhou <zhoufeng.zf@bytedance.com>
>
> Use tc with no verbose, when bpf_btf_attach fail,
> the conditions:
> "if (fd < 0 && (errno == ENOSPC || !ctx->log_size))"
> will make ctx->log_size != 0. And then, bpf_prog_attach,
> ctx->log_size != 0. so enable debug log.
> The verifier log sometimes is so chatty on larger programs.
> bpf_prog_attach is failed.
> "Log buffer too small to dump verifier log 16777215 bytes (9 tries)!"
>
> BTF load failure does not affect prog load. prog still work.
> So when BTF/PROG load fail, enlarge log_size and re-fail with
> having verbose.
>
> Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
> ---
This seems to be targeted against iproute2? It would be good to
specify that as [PATCH iproute2] or something.
> lib/bpf_legacy.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lib/bpf_legacy.c b/lib/bpf_legacy.c
> index 8a03b9c2..d824388c 100644
> --- a/lib/bpf_legacy.c
> +++ b/lib/bpf_legacy.c
> @@ -1531,7 +1531,7 @@ retry:
> * into our buffer. Still, try to give a debuggable error
> * log for the user, so enlarge it and re-fail.
> */
> - if (fd < 0 && (errno == ENOSPC || !ctx->log_size)) {
> + if (fd < 0 && errno == ENOSPC) {
> if (tries++ < 10 && !bpf_log_realloc(ctx))
> goto retry;
>
> @@ -2069,7 +2069,7 @@ retry:
> fd = bpf_btf_load(ctx->btf_data->d_buf, ctx->btf_data->d_size,
> ctx->log, ctx->log_size);
> if (fd < 0 || ctx->verbose) {
> - if (fd < 0 && (errno == ENOSPC || !ctx->log_size)) {
> + if (fd < 0 && errno == ENOSPC) {
> if (tries++ < 10 && !bpf_log_realloc(ctx))
> goto retry;
>
> --
> 2.11.0
>
next prev parent reply other threads:[~2021-07-30 18:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-29 4:55 [PATCH] lib/bpf: Fix btf_load error lead to enable debug log Feng zhou
2021-07-30 18:40 ` Andrii Nakryiko [this message]
2021-08-01 5:59 ` [External] " zhoufeng
-- strict thread matches above, loose matches on Subject: below --
2021-07-28 9:33 Feng zhou
2021-07-29 4:02 ` zhoufeng
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