netdev - Re: [PATCH net] bpf: fix samples to add fake KBUILD

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Message-ID: <581054DC.5000904@iogearbox.net>
Date:   Wed, 26 Oct 2016 09:01:48 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
CC:     davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net] bpf: fix samples to add fake KBUILD_MODNAME

On 10/26/2016 03:17 AM, Alexei Starovoitov wrote:
> On Wed, Oct 26, 2016 at 12:37:53AM +0200, Daniel Borkmann wrote:
>> Some of the sample files are causing issues when they are loaded with tc
>> and cls_bpf, meaning tc bails out while trying to parse the resulting ELF
>> file as program/map/etc sections are not present, which can be easily
>> spotted with readelf(1).
>>
>> Currently, BPF samples are including some of the kernel headers and mid
>> term we should change them to refrain from this, really. When dynamic
>> debugging is enabled, we bail out due to undeclared KBUILD_MODNAME, which
>> is easily overlooked in the build as clang spills this along with other
>> noisy warnings from various header includes, and llc still generates an
>> ELF file with mentioned characteristics. For just playing around with BPF
>> examples, this can be a bit of a hurdle to take.
>>
>> Just add a fake KBUILD_MODNAME as a band-aid to fix the issue, same is
>> done in xdp*_kern samples already.
>>
>> Fixes: 65d472fb007d ("samples/bpf: add 'pointer to packet' tests")
>> Fixes: 6afb1e28b859 ("samples/bpf: Add tunnel set/get tests.")
>> Fixes: a3f74617340b ("cgroup: bpf: Add an example to do cgroup checking in BPF")
>> Reported-by: Chandrasekar Kannan <ckannan@...sole.to>
>> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
>> ---
>>   samples/bpf/parse_ldabs.c        | 1 +
>>   samples/bpf/parse_simple.c       | 1 +
>>   samples/bpf/parse_varlen.c       | 1 +
>>   samples/bpf/tcbpf1_kern.c        | 1 +
>>   samples/bpf/tcbpf2_kern.c        | 1 +
>>   samples/bpf/test_cgrp2_tc_kern.c | 1 +
>>   6 files changed, 6 insertions(+)
>
> It's also needed for all of tracex*_kern.c, right?

Rest compiles just fine for me and readelf output looks good on all
tracex*_kern.o, too.

I see just warnings coming from various kernel header inclusions (see
log), but no errors anymore.

View attachment "log" of type "text/plain" (19110 bytes)