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Date:   Mon, 12 Jun 2023 15:56:10 -0600
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Subject: Re: [PATCH v2] selftests: prctl: Add new prctl test for PR_SET_NAME
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To:     Osama Muhammad <osmtendev@gmail.com>
Cc:     shuah@kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org,
        Shuah Khan <skhan@linuxfoundation.org>
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From:   Shuah Khan <skhan@linuxfoundation.org>
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On 6/10/23 07:01, Osama Muhammad wrote:
> Hi all,
> 
> I looked into it and tried to use TASK_COMM_LEN in the test. Even
> though I included "linux/sched.h '', I was not able to compile the
> test because it couldn't find it in the header file.
> I dived deep into the issue and turns out header file mapped in
> /usr/include/linux/sched.h is actually mapped to
> /include/uapi/linux/sched.h[1] in linux source,
> where TASK_COMM_LEN is not even defined. Instead TASK_COMM_LEN is
> defined in /include/linux/sched.h which is not mapped to any header
> files in
> userspace(/(/usr/include/linux).
> I also tried to find the TASK_COM_LEN in /usr/include/linux/ but I
> couldn't find it. Following are the search results.
> grep -rnw '/usr/include/linux/' -e 'TASK_COMM_LEN"
> RESULTS OF COMMAND :- /usr/include/linux/taskstats.h:38:#define
> TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
> Based on this information, I have two questions:
> 1. Would this require a fix to move 'TASK_COMM_LEN' macro from
> /include/linux/sched.h to UAPI headers /include/uapi/linux/sched.h.
> 2. Is there any other way to access TASK_COMM_LEN in the selftest that
> I'm not aware of?
> 
> [1]:-https://elixir.bootlin.com/linux/v5.15.116/source/include/uapi/linux/sched.h
> 

The best source is Linux mainline.

Take a look at test files that include linux/sched.h

arm64/abi/tpidr2.c is one of them.

Did you install headers before compiling the test?
  make headers_install

thanks,
-- Shuah