linux-kernel - Re: [PATCH v2 4/8] selftests/mm: Add -Wunused family of flags

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20250819155224.23fe3d79896e269bd9e27d04@linux-foundation.org>
Date: Tue, 19 Aug 2025 15:52:24 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Kevin Brodsky <kevin.brodsky@....com>
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>, David Hildenbrand
 <david@...hat.com>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka
 <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan
 <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, Jason Gunthorpe
 <jgg@...pe.ca>, John Hubbard <jhubbard@...dia.com>, Peter Xu
 <peterx@...hat.com>, Leon Romanovsky <leon@...nel.org>, Zi Yan
 <ziy@...dia.com>, Baolin Wang <baolin.wang@...ux.alibaba.com>, Nico Pache
 <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>, Dev Jain
 <dev.jain@....com>, Barry Song <baohua@...nel.org>, Paul Walmsley
 <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, Albert Ou
 <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, linux-riscv@...ts.infradead.org, Shuah Khan
 <shuah@...nel.org>, kernel@...labora.com
Subject: Re: [PATCH v2 4/8] selftests/mm: Add -Wunused family of flags

On Mon, 18 Aug 2025 10:16:35 +0200 Kevin Brodsky <kevin.brodsky@....com> wrote:

> >  # Avoid accidental wrong builds, due to built-in rules working just a little
> >  # bit too well--but not quite as well as required for our situation here.
> >  #
> > @@ -35,6 +34,7 @@ MAKEFLAGS += --no-builtin-rules
> >  
> >  CFLAGS = -Wall -O2 -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES)
> >  CFLAGS += -Wunreachable-code
> > +CFLAGS += -Wunused  -Wunused-parameter -Wunused-function -Wunused-label -Wunused-variable -Wunused-value
> 
> -Wall implies all of these except -Wunused-parameter (at least according
> to gcc(1)).
> 
> As to -Wunused-parameter I am frankly not convinced it's worth the
> hassle. We're getting 90 lines changed in patch 6-8 just to mark
> parameters as unused, in other words noise to keep the compiler happy.
> It is not enabled by default in the kernel proper precisely because it
> is so noisy when callbacks are involved.

Yeah, we rely upon unused parameters in a million places:

#else
static inline void some_stub_function(type1 arg2, type2 arg2)
{
}
#endif