netdev - Re: [PATCH bpf-next] bpftool: fix build failure

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Date:   Mon, 14 Sep 2020 10:43:59 -0700
From:   Yonghong Song <yhs@...com>
To:     Quentin Monnet <quentin@...valent.com>, <bpf@...r.kernel.org>,
        <netdev@...r.kernel.org>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        Andrii Nakryiko <andriin@...com>
Subject: Re: [PATCH bpf-next] bpftool: fix build failure



On 9/14/20 10:23 AM, Quentin Monnet wrote:
> On 14/09/2020 17:54, Yonghong Song wrote:
>>
>>
>> On 9/14/20 9:46 AM, Yonghong Song wrote:
>>>
>>>
>>> On 9/14/20 1:16 AM, Quentin Monnet wrote:
>>>> On 14/09/2020 07:12, Yonghong Song wrote:
>>>>> When building bpf selftests like
>>>>>     make -C tools/testing/selftests/bpf -j20
>>>>> I hit the following errors:
>>>>>     ...
>>>>>     GEN
>>>>> /net-next/tools/testing/selftests/bpf/tools/build/bpftool/Documentation/bpftool-gen.8
>>>>>
>>>>>     <stdin>:75: (WARNING/2) Block quote ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:71: (WARNING/2) Literal block ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:85: (WARNING/2) Literal block ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:57: (WARNING/2) Block quote ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:66: (WARNING/2) Literal block ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:109: (WARNING/2) Literal block ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:175: (WARNING/2) Literal block ends without a blank line;
>>>>> unexpected unindent.
>>>>>     <stdin>:273: (WARNING/2) Literal block ends without a blank line;
>>>>> unexpected unindent.
>>>>>     make[1]: ***
>>>>> [/net-next/tools/testing/selftests/bpf/tools/build/bpftool/Documentation/bpftool-perf.8]
>>>>> Error 12
>>>>>     make[1]: *** Waiting for unfinished jobs....
>>>>>     make[1]: ***
>>>>> [/net-next/tools/testing/selftests/bpf/tools/build/bpftool/Documentation/bpftool-iter.8]
>>>>> Error 12
>>>>>     make[1]: ***
>>>>> [/net-next/tools/testing/selftests/bpf/tools/build/bpftool/Documentation/bpftool-struct_ops.8]
>>>>> Error 12
>>>>>     ...
>>>>>
>>>>> I am using:
>>>>>     -bash-4.4$ rst2man --version
>>>>>     rst2man (Docutils 0.11 [repository], Python 2.7.5, on linux2)
>>>>>     -bash-4.4$
>>>>>
>>>>> Looks like that particular version of rst2man prefers to have a
>>>>> blank line
>>>>> after literal blocks. This patch added block lines in related .rst
>>>>> files
>>>>> and compilation can then pass.
>>>>>
>>>>> Cc: Quentin Monnet <quentin@...valent.com>
>>>>> Fixes: 18841da98100 ("tools: bpftool: Automate generation for "SEE
>>>>> ALSO" sections in man pages")
>>>>> Signed-off-by: Yonghong Song <yhs@...com>
>>>>
>>>>
>>>> Hi Yonghong, thanks for the fix! I didn't see those warnings on my
>>>> setup. For the record my rst2man version is:
>>>>
>>>>      rst2man (Docutils 0.16 [release], Python 3.8.2, on linux)
>>>>
>>>> Your patch looks good, but instead of having blank lines at the end of
>>>> most files, could you please check if the following works?
>>>
>>> Thanks for the tip! I looked at the generated output again. My above
>>> fix can silent the warning, but certainly not correct.
>>>
>>> With the following change, I captured the intermediate result of the
>>> .rst file.
>>>
>>>    ifndef RST2MAN_DEP
>>>           $(error "rst2man not found, but required to generate man pages")
>>>    endif
>>> -       $(QUIET_GEN)( cat $< ; echo -n $(call see_also,$<) ) | rst2man
>>> $(RST2MAN_OPTS) > $@
>>> +       $(QUIET_GEN)( cat $< ; echo -n $(call see_also,$<) ) | tee
>>> /tmp/tt | rst2man $(RST2MAN_OPTS) > $@
>>>
>>> With below command,
>>>      make clean && make bpftool-cgroup.8
>>> I can get the new .rst file for bpftool-cgroup.
>>>
>>> At the end of file /tmp/tt (changed bpftool-cgroup.rst), I see
>>>
>>>       ID       AttachType      AttachFlags     Name
>>> \n SEE ALSO\n========\n\t**bpf**\ (2),\n\t**bpf-helpers**\
>>> (7),\n\t**bpftool**\ (8),\n\t**bpftool-btf**\
>>> (8),\n\t**bpftool-feature**\ (8),\n\t**bpftool-gen**\
>>> (8),\n\t**bpftool-iter**\ (8),\n\t**bpftool-link**\
>>> (8),\n\t**bpftool-map**\ (8),\n\t**bpftool-net**\
>>> (8),\n\t**bpftool-perf**\ (8),\n\t**bpftool-prog**\
>>> (8),\n\t**bpftool-struct_ops**\ (8)\n
>>>
>>> This sounds correct if we rst2man can successfully transforms '\n'
>>> or '\t' to proper encoding in the man page.
>>>
>>> Unfortunately, with my version of rst2man, I got
>>>
>>> .IP "System Message: WARNING/2 (<stdin>:, line 146)"
>>> Literal block ends without a blank line; unexpected unindent.
>>> .sp
>>> n SEE
>>> ALSOn========nt**bpf**(2),nt**bpf\-helpers**(7),nt**bpftool**(8),nt**bpftool\-btf**(8),nt**bpftool\-feature**(8),nt**bpftool\-gen**(8),nt**bpftool\-iter**(8),nt**bpftool\-link**(8),nt**bpftool\-map**(8),nt**bpftool\-net**(8),nt**bpftool\-perf**(8),nt**bpftool\-prog**(8),nt**bpftool\-struct_ops**(8)n
>>>
>>> .\" Generated by docutils manpage writer.
>>>
>>> The rst2man simply considered \n as 'n'. The same for '\t' and
>>> this caused the issue.
>>>
>>> I did not find a way to fix the problem https://urldefense.proofpoint.com/v2/url?u=https-3A__www.google.com_url-3Fq-3Dhttps-3A__zoom.us_j_94864957378-3Fpwd-253DbXFRL1ZaRUxTbDVKcm9uRitpTXgyUT09-26sa-3DD-26source-3Dcalendar-26ust-3D1600532408208000-26usg-3DAOvVaw3SJ0i8oz4ZM-2DGRb7hYkrYlyet&d=DwIDaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=DA8e1B5r073vIqRrFz7MRA&m=kEK7ScPMF-y-i8dli-or8wWEGREW5V4qPB7UqHqDnkg&s=Br0g0MFXxL_pJuDVTOY5UrmvfD2ru_6Uf_X_8Nr2Rhk&e= .
>>
>> The following change works for me.
>>
>> @@ -44,7 +44,7 @@ $(OUTPUT)%.8: %.rst
>>   ifndef RST2MAN_DEP
>>          $(error "rst2man not found, but required to generate man pages")
>>   endif
>> -       $(QUIET_GEN)( cat $< ; echo -n $(call see_also,$<) ) | rst2man
>> $(RST2MAN_OPTS) > $@
>> +       $(QUIET_GEN)( cat $< ; echo -e $(call see_also,$<) ) | rst2man
>> $(RST2MAN_OPTS) > $@
>>
>>   clean: helpers-clean
>>          $(call QUIET_CLEAN, Documentation)
>> -bash-4.4$
>>
>> I will send revision 2 shortly.
> 
> Thanks Yonghong, but this does not work on my setup :/. The version of
> echo which is called on my machine from the Makefile does not seem to
> interpret the "-e" option and writes something like "-e\nSEE ALSO",
> which causes rst2man to complain.
> 
> I suspect the portable option here would be printf, even though Andrii
> had some concerns that we could pass a format specifier through the file
> names [0].
> 
> Would this work on your setup?
> 
> 	$(QUIET_GEN)( cat $< ; printf $(call see_also,$<) ) | rst2man...
> 
> Would that be acceptable?

It works for me. Andrii originally suggested `echo -e`, but since `echo 
-e` does not work in your environment let us use printf then. I will add
a comment about '%' in the bpftool man page name.

> 
> [0]
> https://lore.kernel.org/bpf/ca595fd6-e807-ac8e-f15f-68bfc7b7dbc4@isovalent.com/T/#m01bb298fd512121edd5e77a26ed5382c0c53939e
> 
> Quentin
>