linux-kernel - [PATCH v3 0/3] kbuild: remove gcc's -Wtype-limits

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20251220-remove_wtype-limits-v3-0-24b170af700e@kernel.org>
Date: Sat, 20 Dec 2025 12:02:18 +0100
From: Vincent Mailhol <mailhol@...nel.org>
To: Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nsc@...nel.org>, 
 Nick Desaulniers <nick.desaulniers+lkml@...il.com>, 
 Bill Wendling <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Chris Mason <clm@...com>, David Sterba <dsterba@...e.com>, 
 Kees Cook <kees@...nel.org>, "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, 
 linux-kbuild@...r.kernel.org, linux-sparse@...r.kernel.org, 
 linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, 
 dri-devel@...ts.freedesktop.org, linux-btrfs@...r.kernel.org, 
 linux-hardening@...r.kernel.org, Vincent Mailhol <mailhol@...nel.org>
Subject: [PATCH v3 0/3] kbuild: remove gcc's -Wtype-limits

I often read on the mailing list people saying "who cares about W=2
builds anyway?". At least I do. Not that I want to fix all of them,
but on some occasions, such as new driver submissions, I have often
found a couple valid diagnostics in the W=2 output.

That said, the annoying thing is that W=2 is heavily polluted by one
warning: -Wtype-limits. Try a gcc W=2 build on any file and see the
results for yourself. I suspect this to be the reason why so few
people are using W=2.

This series removes gcc's -Wtype-limits in an attempt to make W=2 more
useful. Those who do not use W=2 can continue to not use it if they
want. Those who, like me, use it for time to time will get an improved
experience from the reduced spam.

Patch #1 deactivates -Wtype-limits.  Extra details on statistics, past
attempts and alternatives are given in the description.

Patch #2 clean-ups the local kbuild -Wno-type-limits exceptions, while
patch #3 undoes a local workaround which silenced that warning by
uglifying the code.

Signed-off-by: Vincent Mailhol <mailhol@...nel.org>
---
Changes in v3:

  - Remove patch #4.

Link to v2: https://lore.kernel.org/r/20251219-remove_wtype-limits-v2-0-2e92b3f566c5@kernel.org

Changes in v2:

  - Add two more patches to clean up some -Wtype-limits workarounds
  - Collect the Reviewed-by tags.

Link to v1: https://lore.kernel.org/r/20251218-remove_wtype-limits-v1-0-735417536787@kernel.org

---
Vincent Mailhol (3):
      kbuild: remove gcc's -Wtype-limits
      kbuild: cleanup local -Wno-type-limits exceptions
      overflow: Remove is_non_negative() and is_negative()

 drivers/gpu/drm/Makefile |  1 -
 fs/btrfs/Makefile        |  1 -
 include/linux/overflow.h | 10 ++--------
 scripts/Makefile.warn    |  4 +++-
 4 files changed, 5 insertions(+), 11 deletions(-)
---
base-commit: 3e7f562e20ee87a25e104ef4fce557d39d62fa85
change-id: 20251205-remove_wtype-limits-c77eb46d09c2

Best regards,
-- 
Vincent Mailhol <mailhol@...nel.org>