ACK: [SRU][J][J:linux-bluefield][PATCH 0/1] scripts/pahole-flags.sh change return to exit 0

[Bartlomiej Zolnierkiewicz]

Acked-by: Bartlomiej Zolnierkiewicz <bartlomiej.zolnierkiewicz at canonical.com>

On Thu, Sep 28, 2023 at 4:25 AM Matthew Ruffell
<matthew.ruffell at canonical.com> wrote:
>
> BugLink: https://bugs.launchpad.net/bugs/2035123
>
> [Impact]
>
> When building the Jammy linux-bluefield kernel tree on a system without pahole
> installed, the following warning is emitted:
>
> ./scripts/pahole-flags.sh: line 7: return: can only `return' from a function or
> sourced script
>
> scripts/pahole-flags.sh attempts to return from an if statement that is not
> within a function, and generates a warning.
>
> The fix is straightforward, changing return to an exit 0.
>
> --- a/scripts/pahole-flags.sh
> +++ b/scripts/pahole-flags.sh
> @@ -4,7 +4,7 @@
>  extra_paholeopt=
>
>  if ! [ -x "$(command -v ${PAHOLE})" ]; then
> -       return
> +       exit 0
>  fi
>
> [Testcase]
>
> Clone the linux-bluefield kernel tree and build it on a arm64 system without
> pahole installed.
>
> A test kernel is available with the fix applied in:
>
> https://launchpad.net/~mruffell/+archive/ubuntu/sf368560-test
>
> Both linux-bluefield and ubuntu-jammy build correctly.
>
> [Fix]
>
> This was fixed by Linus Torvalds in the following merge commit:
>
> commit fc02cb2b37fe2cbf1d3334b9f0f0eab9431766c4
> Merge: bfc484fe6abb 84882cf72cd7
> Author: Linus Torvalds <torvalds at linux-foundation.org>
> Date:   Tue Nov 2 06:20:58 2021 -0700
> Subject: Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fc02cb2b37fe2cbf1d3334b9f0f0eab9431766c4
>
> Note, the original commit does not have the fix included:
>
> commit 9741e07ece7c247dd65e1aa01e16b683f01c05a8
> Author: Jiri Olsa <jolsa at redhat.com>
> Date:   Fri Oct 29 14:57:29 2021 +0200
> Subject: kbuild: Unify options for BTF generation for vmlinux and modules
> Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9741e07ece7c247dd65e1aa01e16b683f01c05a8
>
> The Ubuntu kernel cherry-picked the original commit and did not pick up the
> silent fix made in the merge commit. Submitting the silent fix as a SAUCE patch
> with changelog describing the change.
>
> Note: I know SAUCE patches are bad, but in this scenario, to revert the initial
> commit and re-apply the fixed version would require us to revert two additional
> dependency commits, making six patches to review, vs, a one line change in a
> SAUCE commit that has a real changelog entry.
>
> [Where problems could occur]
>
> The Ubuntu kernel is built with pahole enabled, and requires pahole to be
> installed as a build dependency. It is extremely unlikely that any users are
> disabling pahole at build time, apart from linux-bluefield engineers.
>
> If a regression were to occur, engineers would see errors during build time
> about scripts/pahole-flags.sh not executing properly.
>
> [Other info]
>
> Linus remarked about the issue in the following lkml discussion:
>
> https://lore.kernel.org/lkml/CAHk-=wgdE6=ob5nF60GvRYAG24MKaJBGJf3jPufMe1k_UPBQTA@mail.gmail.com/
> https://lore.kernel.org/lkml/CAHk-=wgPZM4bN=LUCrMkG3FX808QSLm6Uv6ixm5P350_7c=xUw@mail.gmail.com/
>
> This was silently Incorporated into the linux-stable commit:
>
> commit 0baced0e0938f2895ceba54038eaf15ed91032e7 5.15.y
> From: Jiri Olsa <jolsa at redhat.com>
> Date: Sun, 4 Sep 2022 15:19:00 +0200
> Subject: kbuild: Unify options for BTF generation for vmlinux and modules
> Link: https://github.com/gregkh/linux/commit/0baced0e0938f2895ceba54038eaf15ed91032e7
>
> Matthew Ruffell (1):
>   UBUNTU: SAUCE: scripts/pahole-flags.sh change return to exit 0
>
>  scripts/pahole-flags.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>