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Subject: Re: [PATCH 4/4] selftests/bpf: fix compiling errors
To:     "Du, Changbin" <changbin.du@intel.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     shuah@kernel.org, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
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 <20180327022010.57u6rn73inbkrycn@intel.com>
 <20180327030229.txifuth2qmnjo3hy@ast-mbp>
 <20180327030613.hkp7hox3g4prnbsg@intel.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <2dd7c04a-eb10-e730-148e-3b04a18e9b44@iogearbox.net>
Date:   Tue, 27 Mar 2018 10:52:57 +0200
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On 03/27/2018 05:06 AM, Du, Changbin wrote:
> On Mon, Mar 26, 2018 at 08:02:30PM -0700, Alexei Starovoitov wrote:
>> On Tue, Mar 27, 2018 at 10:20:10AM +0800, Du, Changbin wrote:
>>> On Mon, Mar 26, 2018 at 07:55:13AM -0700, Alexei Starovoitov wrote:
>>>> On Mon, Mar 26, 2018 at 05:23:28PM +0800, changbin.du@intel.com wrote:
>>>>> Signed-off-by: Changbin Du <changbin.du@intel.com>
>>>>> ---
>>>>>  tools/testing/selftests/bpf/Makefile | 5 +++--
>>>>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
>>>>> index 5c43c18..dc0fdc8 100644
>>>>> --- a/tools/testing/selftests/bpf/Makefile
>>>>> +++ b/tools/testing/selftests/bpf/Makefile
>>>>> @@ -10,7 +10,8 @@ ifneq ($(wildcard $(GENHDR)),)
>>>>>    GENFLAGS := -DHAVE_GENHDR
>>>>>  endif
>>>>>  
>>>>> -CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include
>>>>> +CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) \
>>>>> +	  -I../../../include -I../../../../usr/include
>>>>>  LDLIBS += -lcap -lelf -lrt -lpthread
>>>>>  
>>>>>  # Order correspond to 'make run_tests' order
>>>>> @@ -62,7 +63,7 @@ else
>>>>>    CPU ?= generic
>>>>>  endif
>>>>>  
>>>>> -CLANG_FLAGS = -I. -I./include/uapi -I../../../include/uapi \
>>>>> +CLANG_FLAGS = -I. -I./include/uapi -I../../../include/uapi -I../../../../usr/include \
>>>>>  	      -Wno-compare-distinct-pointer-types
>>>>
>>>> Nack.
>>>> I suspect that will break the build for everyone else who's doing it in the directory
>>>> itself instead of the outer one.
>>>
>>> This one? But I didn't see any problem.
>>
>> because the build was lucky and additional path ../../../../usr/include didn't point
>> to a valid dir?

Agree.

> I am sorry but I don't understand why you mean *lucky*. Of cause, the path is valid.

The problem is that this suddenly requires users to do a 'make headers_install' in
order to populate usr/include/ directory in the first place. While it's annoying
enough for BPF samples where this is needed, I absolutely don't want to introduce
this for BPF kselftests. It's the wrong approach. Besides, in tools infra, there is
a tools/arch/*/include/uapi/asm/bitsperlong.h header copy already, so we really need
to use that instead. Please adapt your patch accordingly and respin. Please also Cc
us and netdev@vger.kernel.org for BPF kselftests changes.

Thanks,
Daniel