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
