linux-kernel - Re: [PATCH RESEND] powerpc/tools: drop `-o pipefail` in gcc check scripts

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Message-ID: <d3e78669-409f-4041-b194-864019bdd7fc@linux.ibm.com>
Date: Tue, 9 Dec 2025 09:31:11 +0530
From: Madhavan Srinivasan <maddy@...ux.ibm.com>
To: Naveen N Rao <naveen@...nel.org>, Jan Stancek <jstancek@...hat.com>,
        Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org, npiggin@...il.com,
        christophe.leroy@...roup.eu, linux-kernel@...r.kernel.org,
        joe.lawrence@...hat.com
Subject: Re: [PATCH RESEND] powerpc/tools: drop `-o pipefail` in gcc check
 scripts


On 12/3/25 9:29 AM, Naveen N Rao wrote:
> On Tue, Sep 23, 2025 at 05:32:16PM +0200, Jan Stancek wrote:
>> We've been observing rare non-deterministic kconfig failures during
>> olddefconfig, where ARCH_USING_PATCHABLE_FUNCTION_ENTRY was getting
>> disabled and with it number of other config options that depend on it.
>>
>> The reason is that gcc-check-fpatchable-function-entry.sh can fail
>> if `grep -q` (or scripts/dummy-tools/gcc) is fast enough to exit while
>> there is still someone writing on other side of pipe. `pipefail`
>> propagates that error up to kconfig.
>>
>> This can be seen for example with:
>>    # (set -e; set -o pipefail; yes | grep -q y); echo $?
>>    141
>>
>> or by running the actual check script in loop extensively:
>>    ----------------------------- 8< -------------------------------
>>    function kconfig()
>>    {
>>      for i in `seq 1 100`; do
>>        arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh \
>>          ./scripts/dummy-tools/gcc -mlittle-endian \
>>          || { echo "Oops"; exit 1; }
>>      done
>>    }
>>
>>    for ((i=0; i<$(nproc); i++)); do kconfig & done
>>    wait; echo "Done"
>>    ----------------------------- >8 -------------------------------
>>
>> Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry")
>> Fixes: b71c9ffb1405 ("powerpc: Add arch/powerpc/tools directory")
> The latter fixes tag should probably tag one of the below commits which
> actually introduced pipefail, or introduced it in Kconfig:
> Fixes: 8c50b72a3b4f ("powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel")
>    or:
> Fixes: abba759796f9 ("powerpc/kbuild: move -mprofile-kernel check to Kconfig")
>
>> Reported-by: Joe Lawrence <joe.lawrence@...hat.com>
>> Acked-by: Joe Lawrence <joe.lawrence@...hat.com>
>> Signed-off-by: Jan Stancek <jstancek@...hat.com>
>> ---
>>   arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh | 1 -
>>   arch/powerpc/tools/gcc-check-mprofile-kernel.sh           | 1 -
>>   2 files changed, 2 deletions(-)
> Other than that, thanks for fixing this. This LGTM.
> Reviewed-by: Naveen N Rao (AMD) <naveen@...nel.org>
>
> Maddy/Michael,
> Can you please pick this up?
Thanks naveen. Will put it in one of the -rc

Maddy
>
>
> Thanks,
> Naveen
>