Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Fri, 7 Apr 2023 21:07:00 +0200
From:   Andrea Righi <andrea.righi@canonical.com>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>, Tom Rix <trix@redhat.com>,
        Eric Curtin <ecurtin@redhat.com>,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Neal Gompa <neal@gompa.dev>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org,
        llvm@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] scripts: rust: drop is_rust_module.sh
Message-ID: <ZDBp1PaVL7KoqOdD@righiandr-XPS-13-7390>
References: <20230407070517.204676-1-andrea.righi@canonical.com>
 <20230407175318.GA1018455@dev-arch.thelio-3990X>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230407175318.GA1018455@dev-arch.thelio-3990X>
Precedence: bulk

On Fri, Apr 07, 2023 at 10:53:18AM -0700, Nathan Chancellor wrote:
> On Fri, Apr 07, 2023 at 09:05:17AM +0200, Andrea Righi wrote:
> > Commit c1177979af9c ("btf, scripts: Exclude Rust CUs with pahole")
> > introduced the constraint "!DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE"
> > to enable RUST.
> > 
> > With this constraint we don't need is_rust_module.sh anymore, because
> > 'pahole --lang_exclude=rust' already has the capability to exclude Rust
> > CUs. If pahole isn't recent enough (< 1.24) to support --lang_exclude,
> > then DEBUG_INFO_BTF can't be enabled with RUST and is_rust_module.sh
> > isn't used as well.
> > 
> > In any case is_rust_module.sh is obsolete and we can just drop it.
> > 
> > Link: https://lore.kernel.org/lkml/Y+p2xKIN6TJnQinK@righiandr-XPS-13-7390/
> > Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
> 
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> 
> > ---
> >  rust/macros/module.rs     |  2 +-
> >  scripts/Makefile.modfinal |  2 --
> >  scripts/is_rust_module.sh | 16 ----------------
> >  3 files changed, 1 insertion(+), 19 deletions(-)
> >  delete mode 100755 scripts/is_rust_module.sh
> > 
> > diff --git a/rust/macros/module.rs b/rust/macros/module.rs
> > index a7e363c2b044..608406f33a70 100644
> > --- a/rust/macros/module.rs
> > +++ b/rust/macros/module.rs
> > @@ -179,7 +179,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
> >              /// Used by the printing macros, e.g. [`info!`].
> >              const __LOG_PREFIX: &[u8] = b\"{name}\\0\";
> >  
> > -            /// The \"Rust loadable module\" mark, for `scripts/is_rust_module.sh`.
> > +            /// The \"Rust loadable module\" mark.
> >              //
> >              // This may be best done another way later on, e.g. as a new modinfo
> >              // key or a new section. For the moment, keep it simple.
> 
> It seems like this whole section can be dropped? I only see
> __IS_RUST_MODULE used in scripts/is_rust_module.sh, as the comment
> states.

In the scope of the kernel, yes, only is_rust_module.sh used that, but
outside the kernel "something" may still rely on this section. Keeping
it seems safer for now, to avoid potential user-space breakage.

Thanks,
-Andrea