Date:   Thu, 6 Jan 2022 16:48:41 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Ian Rogers <irogers@google.com>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc:     Song Liu <songliubraving@fb.com>, Jiri Olsa <jolsa@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, bpf@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: perf build broken seemingly due to libbpf changes, checking...
Message-ID: <YddHmYhvtVvgqZb/@kernel.org>
References: <YddEVgNKBJiqcV6Y@kernel.org>
 <YddGjjmlMZzxUZbN@kernel.org>
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Em Thu, Jan 06, 2022 at 04:44:14PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Jan 06, 2022 at 04:34:46PM -0300, Arnaldo Carvalho de Melo escreveu:
> > After merging torvalds/master to perf/urgent I'm getting this:
> > 
> > util/bpf-event.c:25:21: error: no previous prototype for ‘btf__load_from_kernel_by_id’ [-Werror=missing-prototypes]
> >    25 | struct btf * __weak btf__load_from_kernel_by_id(__u32 id)
> >       |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > util/bpf-event.c:37:1: error: no previous prototype for ‘bpf_object__next_program’ [-Werror=missing-prototypes]
> >    37 | bpf_object__next_program(const struct bpf_object *obj, struct bpf_program *prev)
> >       | ^~~~~~~~~~~~~~~~~~~~~~~~
> > util/bpf-event.c:46:1: error: no previous prototype for ‘bpf_object__next_map’ [-Werror=missing-prototypes]
> >    46 | bpf_object__next_map(const struct bpf_object *obj, const struct bpf_map *prev)
> >       | ^~~~~~~~~~~~~~~~~~~~
> > util/bpf-event.c:55:1: error: no previous prototype for ‘btf__raw_data’ [-Werror=missing-prototypes]
> >    55 | btf__raw_data(const struct btf *btf_ro, __u32 *size)
> >       | ^~~~~~~~~~~~~
> > cc1: all warnings being treated as errors
> > make[4]: *** [/var/home/acme/git/perf/tools/build/Makefile.build:96: /tmp/build/perf/util/bpf-event.o] Error 1
> > make[4]: *** Waiting for unfinished jobs....
> > util/bpf_counter.c: In function ‘bpf_target_prog_name’:
> > util/bpf_counter.c:82:15: error: implicit declaration of function ‘btf__load_from_kernel_by_id’ [-Werror=implicit-function-declaration]
> >    82 |         btf = btf__load_from_kernel_by_id(info_linear->info.btf_id);
> >       |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > util/bpf_counter.c:82:13: error: assignment to ‘struct btf *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion]
> >    82 |         btf = btf__load_from_kernel_by_id(info_linear->info.btf_id);
> >       |             ^
> > cc1: all warnings being treated as errors
> > make[4]: *** [/var/home/acme/git/perf/tools/build/Makefile.build:96: /tmp/build/perf/util/bpf_counter.o] Error 1
> > 
> > I'm checking now...
> > 
> > BTW I test perf builds with:
> > 
> > make -k BUILD_BPF_SKEL=1 CORESIGHT=1 PYTHON=python3 O=/tmp/build/perf -C tools/perf install-bin && git status && perf test python
> 
> Nevermind, this was due to a patch by Ian Rogers I was testing,
> bisecting get up to the last patch, since I had merged torvalds/master
> today it got me to a wrong correlation, sorry for the disturbance.
> 
> For reference, this is the patch:
> 
> http://lore.kernel.org/lkml/20220106072627.476524-1-irogers@google.com

Ian, I have libbpf-devel installed:

⬢[acme@toolbox perf]$ rpm -qa | grep libbpf
libbpf-0.4.0-1.fc34.x86_64
libbpf-devel-0.4.0-1.fc34.x86_64
⬢[acme@toolbox perf]$

But I'm not using LIBBPF_DYNAMIC=1, so you can't just give precedence to
system headers for all of the homies in tools/lib/.

I bet that if I remove the libbpf-devel package it works, yeah, just
tested. So we need to make those overrides dependent on using
LIBBPF_DYNAMIC=1, LIBTRACEEVENT_DYNAMIC=1, etc and avoid the big hammer
that is -Itools/lib/, using a more finegrained approach, right?

- Arnaldo