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); } -- 2.39.2