On Thu, Aug 28, 2025 at 3:32 PM Joe Lawrence <joe.lawre...@redhat.com> wrote:
>
> On 8/26/25 5:54 AM, 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")
> > Signed-off-by: Jan Stancek <jstan...@redhat.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(-)
> >
> > diff --git a/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
> > b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
> > index 06706903503b..baed467a016b 100755
> > --- a/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
> > +++ b/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh
> > @@ -2,7 +2,6 @@
> > # SPDX-License-Identifier: GPL-2.0
> >
> > set -e
> > -set -o pipefail
> >
> > # To debug, uncomment the following line
> > # set -x
> > diff --git a/arch/powerpc/tools/gcc-check-mprofile-kernel.sh
> > b/arch/powerpc/tools/gcc-check-mprofile-kernel.sh
> > index 73e331e7660e..6193b0ed0c77 100755
> > --- a/arch/powerpc/tools/gcc-check-mprofile-kernel.sh
> > +++ b/arch/powerpc/tools/gcc-check-mprofile-kernel.sh
> > @@ -2,7 +2,6 @@
> > # SPDX-License-Identifier: GPL-2.0
> >
> > set -e
> > -set -o pipefail
> >
> > # To debug, uncomment the following line
> > # set -x
>
> Acked-by: Joe Lawrence <joe.lawre...@redhat.com>
>
> This bug manifests when automated scripts expect to run a kernel build
> after `make olddefconfig`. I reported this to Jan when I found that
Right, maybe we can still add that too.
Reported-by: Joe Lawrence <joe.lawre...@redhat.com>
Would anyone else also care to review, please?
Thanks,
Jan
> kpatch-build [1] instances were hanging (expecting to hear from a user
> that would never answer :(
>
> [1] https://github.com/dynup/kpatch/blob/master/kpatch-build/kpatch-build
> --
> Joe
>
