On 4/18/23 10:55 AM, Thomas Richter wrote:
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;
The problem is however for current bpf-next, where this change breaks CI:
https://github.com/kernel-patches/bpf/actions/runs/4737651765/jobs/8410684531
[...]
CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/bpftool/feature.o
CC /tmp/work/bpf/bpf/tools/testing/selftests/bpf/tools/build/bpftool/disasm.o
btf_dumper.c:838:4: error: use of undeclared identifier 'fallthrough'
fallthrough;
^
1 error generated.
[...]
I would suggest as a clean path that'll work for both to just change from
fallthrough; into /* fallthrough */ as done in objtool, then we can also
work around BPF CI issue and merge this change in time.
default:
putchar(*s);
}
