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From: Jiri Benc <jbenc@redhat•com>
To: Andrii Nakryiko <andriin@fb•com>
Cc: <bpf@vger•kernel.org>, <netdev@vger•kernel.org>, <ast@fb•com>,
	<daniel@iogearbox•net>, <andrii.nakryiko@gmail•com>,
	<kernel-team@fb•com>
Subject: Re: [PATCH v3 bpf-next] bpf: make verifier log more relevant by default
Date: Thu, 5 Nov 2020 17:02:02 +0100	[thread overview]
Message-ID: <20201105170202.5bb47fef@redhat.com> (raw)
In-Reply-To: <20200423195850.1259827-1-andriin@fb.com>

On Thu, 23 Apr 2020 12:58:50 -0700, Andrii Nakryiko wrote:
> To make BPF verifier verbose log more releavant and easier to use to debug
> verification failures, "pop" parts of log that were successfully verified.
> This has effect of leaving only verifier logs that correspond to code branches
> that lead to verification failure, which in practice should result in much
> shorter and more relevant verifier log dumps. This behavior is made the
> default behavior and can be overriden to do exhaustive logging by specifying
> BPF_LOG_LEVEL2 log level.

This patch broke the test_offload.py selftest:

[...]
Test TC offloads work...
FAIL: Missing or incorrect message from netdevsim in verifier log
[...]

The selftest expects to receive "[netdevsim] Hello from netdevsim!" in
the log (coming from nsim_bpf_verify_insn) but that part of the log is
cleared by bpf_vlog_reset added by this patch.

How can this be fixed? The log level 1 comes from the "verbose" keyword
passed to tc, I don't think it should be increased to 2.

On a related note, the selftest had to start failing after this commit.
It's a bit surprising it did not get caught, is there a bug somewhere
in the test matrix?

Thanks,

 Jiri


  parent reply	other threads:[~2020-11-05 16:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-23 19:58 [PATCH v3 bpf-next] bpf: make verifier log more relevant by default Andrii Nakryiko
2020-04-26 16:57 ` Alexei Starovoitov
2020-04-28  4:55   ` Andrii Nakryiko
2020-11-05 16:02 ` Jiri Benc [this message]
2020-11-05 21:22   ` Andrii Nakryiko
2020-11-05 21:53     ` Jakub Kicinski
2020-11-05 22:41       ` Andrii Nakryiko
2020-11-05 22:57         ` Jakub Kicinski
2020-11-06  8:24           ` Jiri Benc
2020-11-06 18:52             ` Jakub Kicinski
2020-11-06  8:26     ` Jiri Benc

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