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 <[email protected]>
> Acked-by: Joe Lawrence <[email protected]>
> Signed-off-by: Jan Stancek <[email protected]>
> ---
> 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) <[email protected]>
Maddy/Michael,
Can you please pick this up?
Thanks,
Naveen
