Full quote below for reference.
Mark or Stephen could you please add the patch below to linux-next?
This solves a merge conflict between perf tree commit f7a858bffcdd ("tools:
Rename __fallthrough to fallthrough") and bpf-next tree commit 9fd496848b1c
("bpftool: Support inline annotations when dumping the CFG of a program").
FWIW, the perf tree commit also seems to have missed an additional
occurence of __fallthrough in samples/bpf/hbm.c.
Thanks!
On Wed, Apr 12, 2023 at 02:27:23PM +0100, Quentin Monnet wrote:
> 2023-04-12 14:36 UTC+0200 ~ Thomas Richter <tmricht@xxxxxxxxxxxxx>
> > Commit 9fd496848b1c ("bpftool: Support inline annotations when dumping the CFG of a program")
> > breaks the build of the perf tool on s390 in the linux-next repository.
> > Here is the make output:
> >
> > make -C tools/perf
> > ....
> > btf_dumper.c: In function 'dotlabel_puts':
> > DEBUG: btf_dumper.c:838:25: error: '__fallthrough' undeclared \
> > (first use in this function); did you mean 'fallthrough'?
> > DEBUG: 838 | __fallthrough;
> > DEBUG: | ^~~~~~~~~~~~~
> > DEBUG: | fallthrough
> > DEBUG: btf_dumper.c:838:25: note: each undeclared identifier is reported \
> > only once for each function it appears in
> > DEBUG: btf_dumper.c:837:25: warning: this statement may fall through \
> > [-Wimplicit-fallthrough=]
> > DEBUG: 837 | putchar('\\');
> > DEBUG: | ^~~~~~~~~~~~~
> > DEBUG: btf_dumper.c:839:17: note: here
> > DEBUG: 839 | default:
> > DEBUG: | ^~~~~~~
> > DEBUG: make[3]: *** [Makefile:247: /builddir/build/BUILD/kernel-6.2.fc37/\
> > linux-6.2/tools/perf/util/bpf_skel/ \
> > .tmp/bootstrap/btf_dumper.o] Error 1
> >
> > The compile fails because symbol __fallthrough unknown, but symbol
> > fallthrough is known and works fine.
> >
> > Fix this and replace __fallthrough by fallthrough.
> >
> > With this change, the compile works.
> >
> > Output after:
> >
> > # make -C tools/perf
> > ....
> > CC util/bpf-filter.o
> > CC util/bpf-filter-flex.o
> > LD util/perf-in.o
> > LD perf-in.o
> > LINK perf
> > make: Leaving directory '/root/mirror-linux-next/tools/perf'
> > #
> >
> > Fixes: 9fd496848b1c ("bpftool: Support inline annotations when dumping the CFG of a program")
> > Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
> > ---
> > tools/bpf/bpftool/btf_dumper.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
> > index 6c5e0e82da22..1b7f69714604 100644
> > --- a/tools/bpf/bpftool/btf_dumper.c
> > +++ b/tools/bpf/bpftool/btf_dumper.c
> > @@ -835,7 +835,7 @@ static void dotlabel_puts(const char *s)
> > case '|':
> > case ' ':
> > putchar('\\');
> > - __fallthrough;
> > + fallthrough;
> > default:
> > putchar(*s);
> > }
>
> Also reported by Sven Schnelle, and discussed at
> https://lore.kernel.org/all/yt9dttxlwal7.fsf@xxxxxxxxxxxxx/.
>
> This is for linux-next, it cannot go through bpf-next given that commit
> f7a858bffcdd ("tools: Rename __fallthrough to fallthrough") is not in
> there yet.
>
> Acked-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
>
> Thanks!
> Quentin
