Re: linux-next: build failure after merge of the net-next tree

[Andrii Nakryiko]

On Thu, Sep 5, 2019 at 7:53 PM Masahiro Yamada
<yamada.masahiro@xxxxxxxxxxxxx> wrote:
>
> On Fri, Sep 6, 2019 at 4:26 AM Andrii Nakryiko
> <andrii.nakryiko@xxxxxxxxx> wrote:
> >
> > On Tue, Sep 3, 2019 at 11:20 PM Masahiro Yamada
> > <yamada.masahiro@xxxxxxxxxxxxx> wrote:
> > >
> > > On Wed, Sep 4, 2019 at 3:00 PM Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> 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!
>
> I could have pointed it out if I had noticed
> it in the review process.
>
> I actually noticed your patch by Stephen's
> former email.  (i.e. when it appeared in linux-next)
>
> (I try my best to check kbuild ML, and also search for
> my name in LKML in case I am explicitly addressed,
> but a large number of emails fall off my filter)
>
> It was somewhat too late when I noticed it.
> Of course, I still could email you afterward, or even send a patch to btf ML,
> but I did not fix a particular instance of breakage
> because there are already the same type of breakages in code base.
>
> Then, I applied the all-or-nothing checker because I thought it was
> the only way to address the root cause of the problems.
>
> I admit I could have done the process better.
> Sorry if I made people uncomfortable and waste time.

No worries. Thanks for candid answer. I just wanted to make sure there
are no hard feelings and I can engage your expertise effectively in
the future for kbuild stuff to ensure issues like this don't slip
through, if we ever have to do anything like this for BPF-related
things again. I'll keep CC'ing you and will add kbuild ML as well.
Thanks!

>
> 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@xxxxxxxxxxxxxxxx>
> > > > 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@xxxxxxxxxxxxxxxx>
> > > > ---
> > > >  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
>
>
>
> --
> Best Regards
> Masahiro Yamada