linux-kernel - Re: [PATCH v2 1/2] tools/resolve_btfids: Add --fatal-warnings option

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Message-ID: <CAEf4BzZqeo00C5a9QO6Ah3i-doWRbg7v_2y=y9Kfg3=JyrA=zQ@mail.gmail.com>
Date: Tue, 3 Dec 2024 18:06:26 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Thomas Weißschuh <linux@...ssschuh.net>
Cc: Masahiro Yamada <masahiroy@...nel.org>, Nathan Chancellor <nathan@...nel.org>, 
	Nicolas Schier <nicolas@...sle.eu>, Alexei Starovoitov <ast@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, linux-kbuild@...r.kernel.org, 
	linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v2 1/2] tools/resolve_btfids: Add --fatal-warnings option

On Tue, Dec 3, 2024 at 3:09 PM Thomas Weißschuh <linux@...ssschuh.net> wrote:
>
> On 2024-12-03 14:31:01-0800, Andrii Nakryiko wrote:
> > On Tue, Nov 26, 2024 at 1:17 PM Thomas Weißschuh <linux@...ssschuh.net> wrote:
> > >
> > > Currently warnings emitted by resolve_btfids are buried in the build log
> > > and are slipping into mainline frequently.
> > > Add an option to elevate warnings to hard errors so the CI bots can
> > > catch any new warnings.
> > >
> > > Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> > > Acked-by: Jiri Olsa <jolsa@...nel.org>
> > > ---
> > >  tools/bpf/resolve_btfids/main.c | 12 ++++++++++--
> > >  1 file changed, 10 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> > > index bd9f960bce3d5b74dc34159b35af1e0b33524d2d..571d29d2da97fea75e5f9c544a95b9ac65f9e579 100644
> > > --- a/tools/bpf/resolve_btfids/main.c
> > > +++ b/tools/bpf/resolve_btfids/main.c
> > > @@ -141,6 +141,7 @@ struct object {
> > >  };
> > >
> > >  static int verbose;
> > > +static int warnings;
> > >
> > >  static int eprintf(int level, int var, const char *fmt, ...)
> > >  {
> > > @@ -604,6 +605,7 @@ static int symbols_resolve(struct object *obj)
> > >                         if (id->id) {
> > >                                 pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",
> > >                                         str, id->id, type_id, id->id);
> > > +                               warnings++;
> > >                         } else {
> > >                                 id->id = type_id;
> > >                                 (*nr)--;
> > > @@ -625,8 +627,10 @@ static int id_patch(struct object *obj, struct btf_id *id)
> > >         int i;
> > >
> > >         /* For set, set8, id->id may be 0 */
> > > -       if (!id->id && !id->is_set && !id->is_set8)
> > > +       if (!id->id && !id->is_set && !id->is_set8) {
> > >                 pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
> > > +               warnings++;
> > > +       }
> > >
> > >         for (i = 0; i < id->addr_cnt; i++) {
> > >                 unsigned long addr = id->addr[i];
> > > @@ -782,6 +786,7 @@ int main(int argc, const char **argv)
> > >                 .funcs    = RB_ROOT,
> > >                 .sets     = RB_ROOT,
> > >         };
> > > +       bool fatal_warnings = false;
> > >         struct option btfid_options[] = {
> > >                 OPT_INCR('v', "verbose", &verbose,
> > >                          "be more verbose (show errors, etc)"),
> > > @@ -789,6 +794,8 @@ int main(int argc, const char **argv)
> > >                            "BTF data"),
> > >                 OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
> > >                            "path of file providing base BTF"),
> > > +               OPT_BOOLEAN(0, "fatal-warnings", &fatal_warnings,
> > > +                           "turn warnings into errors"),
> >
> > We are mixing naming styles here: we have "btf_base" with underscore
> > separator, and you are adding "fatal-warnings" with dash separator. I
> > personally like dashes, but whichever way we should stay consistent.
> > So let's fix it, otherwise it looks a bit sloppy.
>
> Ack.
>
> >
> > Please also use [PATCH bpf-next v3] subject prefix to make it explicit
> > that this should go through bpf-next tree.
>
> Ack.
>
> >
> > pw-bot: cr
> >
> > >                 OPT_END()
> > >         };
> > >         int err = -1;
> > > @@ -823,7 +830,8 @@ int main(int argc, const char **argv)
> > >         if (symbols_patch(&obj))
> > >                 goto out;
> > >
> > > -       err = 0;
> > > +       if (!(fatal_warnings && warnings))
> > > +               err = 0;
> >
> > nit: just
> >
> > if (!fatal_warnings)
> >     err = 0;
> >
> > ?
>
> This seems wrong. Now the actual warning counter is never evaluated.
> And --fatal_warnings will always lead to an error exit code.

Ah, I missed that you are using default -1 value here. I wonder if we
should make it a bit more explicit?

if (fatal_warnings)
    err = warnings ? -1 : 0;
else
    err = 0;

Something like that?

>
> > >  out:
> > >         if (obj.efile.elf) {
> > >                 elf_end(obj.efile.elf);
> > >
> > > --
> > > 2.47.1
> > >