Quentin Monnet <quentin@xxxxxxxxxxxxx> writes:
> 2023-04-12 08:04 UTC+0200 ~ Sven Schnelle <svens@xxxxxxxxxxxxx>
>> Quentin Monnet <quentin@xxxxxxxxxxxxx> writes:
>>
>>> diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
>>> index e7f6ec3a8f35..583aa843df92 100644
>>> --- a/tools/bpf/bpftool/btf_dumper.c
>>> +++ b/tools/bpf/bpftool/btf_dumper.c
>>> @@ -821,3 +821,37 @@ void btf_dump_linfo_json(const struct btf *btf,
>>> BPF_LINE_INFO_LINE_COL(linfo->line_col));
>>> }
>>> }
>>> +
>>> +static void dotlabel_puts(const char *s)
>>> +{
>>> + for (; *s; ++s) {
>>> + switch (*s) {
>>> + case '\\':
>>> + case '"':
>>> + case '{':
>>> + case '}':
>>> + case '<':
>>> + case '>':
>>> + case '|':
>>> + case ' ':
>>> + putchar('\\');
>>> + __fallthrough;
>>
>> Is __fallthrough correct? I see the following compile error on s390 in
>> linux-next (20230412):
>>
>> CC btf_dumper.o
>> btf_dumper.c: In function ‘dotlabel_puts’:
>> btf_dumper.c:838:25: error: ‘__fallthrough’ undeclared (first use in this function); did you mean ‘fallthrough’?
>> 838 | __fallthrough;
>> | ^~~~~~~~~~~~~
>>
>> removing the two underscores fixes this.
>
> I thought so? Perf seems to use the double underscores as well. Just
> "fallthrough" does not seem to be the right fix anyway, it gives me an
> error similar to yours on x86_64 with "fallthrough" undeclared.
>
> The definition should be pulled from tools/include/linux/compiler.h (and
> .../compiler-gcc.h). I thought this file would be at least included from
> bpftool's main.h, in turn included in btf_dumper.c. Looking at the chain
> of inclusions, on my system I get the following path:
>
> $ CFLAGS=-H make btf_dumper.o
> [...]
> . /root/dev/linux/tools/include/linux/bitops.h
> [...]
> .. /root/dev/linux/tools/include/linux/bits.h
> [...]
> ... /root/dev/linux/tools/include/linux/build_bug.h
> .... /root/dev/linux/tools/include/linux/compiler.h
> ..... /root/dev/linux/tools/include/linux/compiler_types.h
> ...... /root/dev/linux/tools/include/linux/compiler-gcc.h
> [...]
>
> What do you get on your side?
>
> If you add "#include <linux/compiler.h>" to btf_dumper.c directly, does
> it fix the issue?
This seems to clash with:
commit f7a858bffcddaaf70c71b6b656e7cc21b6107cec
Author: Liam Howlett <liam.howlett@xxxxxxxxxx>
Date: Fri Nov 25 15:50:16 2022 +0000
tools: Rename __fallthrough to fallthrough
Rename the fallthrough attribute to better align with the kernel
version. Copy the definition from include/linux/compiler_attributes.h
including the #else clause. Adding the #else clause allows the tools
compiler.h header to drop the check for a definition entirely and keeps
both definitions together.
Change any __fallthrough statements to fallthrough anywhere it was used
within perf.
This allows other tools to use the same key word as the kernel.
Which was also merged in linux-next.
