Date:   Mon, 14 Sep 2020 09:54:40 -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>
Subject: Re: [PATCH bpf-next] bpftool: fix build failure



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 yet.

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.

> 
>>
>> ------
>>
>> diff --git a/tools/bpf/bpftool/Documentation/Makefile
>> b/tools/bpf/bpftool/Documentation/Makefile
>> index 4c9dd1e45244..01b30ed86eac 100644
>> --- a/tools/bpf/bpftool/Documentation/Makefile
>> +++ b/tools/bpf/bpftool/Documentation/Makefile
>> @@ -32,7 +32,7 @@ RST2MAN_OPTS += --verbose
>>
>>   list_pages = $(sort $(basename $(filter-out $(1),$(MAN8_RST))))
>>   see_also = $(subst " ",, \
>> -       "\n" \
>> +       "\n\n" \
>>          "SEE ALSO\n" \
>>          "========\n" \
>>          "\t**bpf**\ (2),\n" \
>>

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