Re: [PATCH] lib/bpf: Fix btf_load error lead to enable debug log
From: Andrii Nakryiko <hidden>
Date: 2021-07-30 18:40:43
On Wed, Jul 28, 2021 at 9:55 PM Feng zhou [off-list ref] wrote:
From: Feng Zhou <redacted> 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 <redacted> ---
This seems to be targeted against iproute2? It would be good to specify that as [PATCH iproute2] or something.
quoted hunk ↗ jump to hunk
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