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Date: Thu, 26 Feb 2026 13:26:48 -0700
From: Nathan Chancellor <nathan@kernel.org>
To: sun jian <sun.jian.kdev@gmail.com>
Cc: Nicolas Schier <nsc@kernel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	Florian Westphal <fw@strlen.de>, linux-kernel@vger.kernel.org,
	linux-kbuild@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH] genksyms: Fix parsing a declarator with a preceding
 attribute
Message-ID: <20260226202648.GA3196155@ax162>
References: <20260225-genksyms-fix-attribute-declarator-v1-1-1b21478663fb@kernel.org>
 <CABFUUZGgnKF+C7f7yPkXybFq1KBOJNj3s73R41ru1+aGUGYUQw@mail.gmail.com>
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On Thu, Feb 26, 2026 at 12:36:00PM +0800, sun jian wrote:
> On Thu, Feb 26, 2026 at 6:07 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > After commit 07919126ecfc ("netfilter: annotate NAT helper hook pointers
> > with __rcu"), genksyms fails to parse the __rcu annotation when building
> > with CONFIG_DEBUG_INFO_BTF=y, CONFIG_PAHOLE_HAS_BTF_TAG=y, and a version
> > of clang that supports btf_type_tag.
> 
> Hi Nathan,
> 
> Thanks for tracking this down and for the minimal reproducer.
> 
> I've noticed the same thing while building on my laptop during MODPOST
> Module.symvers:
> 
> WARNING: modpost: EXPORT symbol "nf_nat_ftp_hook" [vmlinux] version
> generation failed, symbol will not be versioned.
> Is "nf_nat_ftp_hook" prototyped in <asm/asm-prototypes.h>?
> WARNING: modpost: EXPORT symbol "nf_nat_irc_hook" [vmlinux] version
> generation failed, symbol will not be versioned.
> Is "nf_nat_irc_hook" prototyped in <asm/asm-prototypes.h>?
> 
> >
> > diff --git a/scripts/genksyms/parse.y b/scripts/genksyms/parse.y
> > index efdcf07c4eb6..cabcd146f3aa 100644
> > --- a/scripts/genksyms/parse.y
> > +++ b/scripts/genksyms/parse.y
> > @@ -325,8 +325,8 @@ direct_declarator:
> >                 { $$ = $4; }
> >         | direct_declarator BRACKET_PHRASE
> >                 { $$ = $2; }
> > -       | '(' declarator ')'
> > -               { $$ = $3; }
> > +       | '(' attribute_opt declarator ')'
> > +               { $$ = $4; }
> >         ;
> >
> 
> Your grammar tweak to allow an optional attribute before the nested
> declarator looks correct to me.

Thanks a lot for taking a look!

Cheers,
Nathan