netdev - Re: [PATCH net-next 6/9] bpf: fix stack_depth usage by test

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Message-ID: <73af1b50-38b0-b7f3-5c74-e425d47209b6@fb.com>
Date:   Wed, 31 May 2017 11:39:37 -0700
From:   Alexei Starovoitov <ast@...com>
To:     David Miller <davem@...emloft.net>
CC:     <daniel@...earbox.net>, <netdev@...r.kernel.org>,
        <kernel-team@...com>
Subject: Re: [PATCH net-next 6/9] bpf: fix stack_depth usage by test_bpf.ko

On 5/31/17 11:15 AM, David Miller wrote:
> From: Alexei Starovoitov <ast@...com>
> Date: Tue, 30 May 2017 13:31:32 -0700
>
>> test_bpf.ko doesn't call verifier before selecting interpreter or JITing,
>> hence the tests need to manually specify the amount of stack they consume.
>>
>> Signed-off-by: Alexei Starovoitov <ast@...nel.org>
>> Acked-by: Daniel Borkmann <daniel@...earbox.net>
>
> I do not like this and the previous patch, it seems so error prone.

in what sense 'error prone' ?
we cannot call verifier from test_bpf.ko, since the test are written
in raw (post-verifier) format and not uapi format.
If we decide to rewrite them most of the large tests will not pass
due to hitting verifier limits.
test_bpf is a unit test to test JITs. It shouldn't test verifier
or other bpf components. It's a job of test_verifier, test_maps
and other tests.
Hence the only way is to manually set stack_depth here.