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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Thu, 5 Sep 2019 12:26:13 -0700
Message-ID: <CAEf4BzZLBV3o=t9+a4o4T7KZ_M04vddD0RMVs3s4JvDsvQ8onA@mail.gmail.com>
Subject: Re: linux-next: build failure after merge of the net-next tree
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     Stephen Rothwell <sfr@canb.auug.org.au>,
        David Miller <davem@davemloft.net>,
        Networking <netdev@vger.kernel.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Andrii Nakryiko <andriin@fb.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Alexei Starovoitov <ast@fb.com>
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On Tue, Sep 3, 2019 at 11:20 PM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> On Wed, Sep 4, 2019 at 3:00 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> >
> > Hi all,
> >
> > After merging the net-next tree, today's linux-next build (arm
> > multi_v7_defconfig) failed like this:
> >
> > scripts/link-vmlinux.sh: 74: Bad substitution
> >
> > Caused by commit
> >
> >   341dfcf8d78e ("btf: expose BTF info through sysfs")
> >
> > interacting with commit
> >
> >   1267f9d3047d ("kbuild: add $(BASH) to run scripts with bash-extension")
> >
> > from the kbuild tree.
>
>
> I knew that they were using bash-extension
> in the #!/bin/sh script.  :-D
>
> In fact, I wrote my patch in order to break their code
> and  make btf people realize that they were doing wrong.

Was there a specific reason to wait until this would break during
Stephen's merge, instead of giving me a heads up (or just replying on
original patch) and letting me fix it and save everyone's time and
efforts?

Either way, I've fixed the issue in
https://patchwork.ozlabs.org/patch/1158620/ and will pay way more
attention to BASH-specific features going forward (I found it pretty
hard to verify stuff like this, unfortunately). But again, code review
process is the best place to catch this and I really hope in the
future we can keep this process productive. Thanks!

>
>
>
> > The change in the net-next tree turned link-vmlinux.sh into a bash script
> > (I think).
> >
> > I have applied the following patch for today:
>
>
> But, this is a temporary fix only for linux-next.
>
> scripts/link-vmlinux.sh does not need to use the
> bash-extension ${@:2} in the first place.
>
> I hope btf people will write the correct code.

I replaced ${@:2} with shift and ${@}, I hope that's a correct fix,
but if you think it's not, please reply on the patch and let me know.


>
> Thanks.
>
>
>
>
> > From: Stephen Rothwell <sfr@canb.auug.org.au>
> > Date: Wed, 4 Sep 2019 15:43:41 +1000
> > Subject: [PATCH] link-vmlinux.sh is now a bash script
> >
> > Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> > ---
> >  Makefile                | 4 ++--
> >  scripts/link-vmlinux.sh | 2 +-
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index ac97fb282d99..523d12c5cebe 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -1087,7 +1087,7 @@ ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
> >
> >  # Final link of vmlinux with optional arch pass after final link
> >  cmd_link-vmlinux =                                                 \
> > -       $(CONFIG_SHELL) $< $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_vmlinux) ;    \
> > +       $(BASH) $< $(LD) $(KBUILD_LDFLAGS) $(LDFLAGS_vmlinux) ;    \
> >         $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
> >
> >  vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
> > @@ -1403,7 +1403,7 @@ clean: rm-files := $(CLEAN_FILES)
> >  PHONY += archclean vmlinuxclean
> >
> >  vmlinuxclean:
> > -       $(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean
> > +       $(Q)$(BASH) $(srctree)/scripts/link-vmlinux.sh clean
> >         $(Q)$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) clean)
> >
> >  clean: archclean vmlinuxclean
> > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> > index f7edb75f9806..ea1f8673869d 100755
> > --- a/scripts/link-vmlinux.sh
> > +++ b/scripts/link-vmlinux.sh
> > @@ -1,4 +1,4 @@
> > -#!/bin/sh
> > +#!/bin/bash
> >  # SPDX-License-Identifier: GPL-2.0
> >  #
> >  # link vmlinux
> > --
> > 2.23.0.rc1
> >
> > --
> > Cheers,
> > Stephen Rothwell
>
>
>
> --
> Best Regards
> Masahiro Yamada