From nobody Sun Feb 8 08:42:46 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4140C2FF151; Thu, 18 Dec 2025 18:51:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766083878; cv=none; b=Bz3c84TghmoH0hjvLVjQNEVOtNxE3jqXmVKgdA8EH0gstYvcuc9TOeJ/QboHq6B8G9L1109f8Z26tmPMNy9gnm90ORtduQZBa2ba/+TzdUHj0GtOMrG5JHre74C9yULGPKyfkzgUSCcwYjieyEandb3ToPvS9LnRRz3yeDeNJy8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766083878; c=relaxed/simple; bh=exaDAmGfwhCHtzCgNSX0Gj1Y2mOtWbeMcXCXNwxDLyo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=fGNfsvLTwNd8Zx2pLVDuuo3rZrdEcc+0587kdK1tW1Zy5CuOaurLo8+wC8oO51xg42UyiC0ecykImUESIUJms/JPvS1qdsL8iRZ8657/JVLF/YaWmkbWlUQiFOipZqNmyLiNIDFzZIC5Jjp+OHaqHB5t0zgrU8MsgOS/Ys7TrQs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hkv1DLya; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hkv1DLya" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C11E8C113D0; Thu, 18 Dec 2025 18:51:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766083877; bh=exaDAmGfwhCHtzCgNSX0Gj1Y2mOtWbeMcXCXNwxDLyo=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Hkv1DLyatcAsPlTRs+4Xw1lfj5uiLRivczjAKo2QElFDeDj8qx31NBccRCSRn/mUd n17MZADFPRhePYovV4ZOWzYZM86ddnTIu7CUjejpPdXrrv6dEq2MLLwel9QI+HsfI7 F+01kRDyDlIaRDkDZhZ58iboR78cMZgGQsdZXNTLzBqXNLkIm1qVVzuD1qfwSAnN9T TDVV68hWOD4nzO9gnt5EfioLIGmIb+9fiH0tJaK4zZEcDlQhMCW8QJ9385UANoLGNM BG/IwE6jlSgTBf5dDUydnE+WjFrCtBaLYrEir2rlUBTJeCb+wlnpMFgGWjwtbIjC5m 7uDg0/fBwHGpw== From: Vincent Mailhol Date: Thu, 18 Dec 2025 19:50:01 +0100 Subject: [PATCH 1/2] kbuild: remove gcc's -Wtype-limits Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251218-remove_wtype-limits-v1-1-735417536787@kernel.org> References: <20251218-remove_wtype-limits-v1-0-735417536787@kernel.org> In-Reply-To: <20251218-remove_wtype-limits-v1-0-735417536787@kernel.org> To: Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Chris Mason , David Sterba Cc: Linus Torvalds , linux-kbuild@vger.kernel.org, linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-btrfs@vger.kernel.org, Vincent Mailhol X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3554; i=mailhol@kernel.org; h=from:subject:message-id; bh=exaDAmGfwhCHtzCgNSX0Gj1Y2mOtWbeMcXCXNwxDLyo=; b=owGbwMvMwCV2McXO4Xp97WbG02pJDJkuviKiT3NXWfh0WfVtbeAKVD/uLhp6XnFJwlG1vWf29 G+8b/SnYyILgxgXg6WYIsuyck5uhY5C77BDfy1h5rAygQyRFmlgAAIWBr7cxLxSIx0jPVNtQz1D Qx0gk4GLUwCmWj6XkWHlnwf52/b/2fb670nmUO7zWt0NAVMXpzKfzEtK3PHQxXsywz/lgKlhAd5 cVW/m7vqXukX3d2JP/X07NqbMOdMrQw5GFnIDAA== X-Developer-Key: i=mailhol@kernel.org; a=openpgp; fpr=ED8F700574E67F20E574E8E2AB5FEB886DBB99C2 W=3D2 builds are heavily polluted by the -Wtype-limits warning. Here are some W=3D12 statistics on Linux v6.19-rc1 for an x86_64 defconfig (with just CONFIG_WERROR set to "n") using gcc 14.3.1: Warning name count percent ------------------------------------------------- -Wlogical-op 2 0.00 % -Wmaybe-uninitialized 138 0.20 % -Wunused-macros 869 1.24 % -Wmissing-field-initializers 1418 2.02 % -Wshadow 2234 3.19 % -Wtype-limits 65378 93.35 % ------------------------------------------------- Total 70039 100.00 % As we can see, -Wtype-limits represents the vast majority of all warnings. The reason behind this is that these warnings appear in some common header files, meaning that some unique warnings are repeated tens of thousands of times (once per header inclusion). Add to this the fact that each warning is coupled with a dozen lines detailing some macro expansion. The end result is that the W=3D2 output is just too bloated and painful to use. Three years ago, I proposed in [1] modifying one such header to silence that noise. Because the code was not faulty, Linus rejected the idea and instead suggested simply removing that warning. At that time, I could not bring myself to send such a patch because, despite its problems, -Wtype-limits would still catch the below bug: unsigned int ret; ret =3D check(); if (ret < 0) error(); Meanwhile, based on another suggestion from Linus, I added a new check to sparse [2] that would catch the above bug without the useless spam. With this, remove gcc's -Wtype-limits. People who still want to catch incorrect comparisons between unsigned integers and zero can now use sparse instead. On a side note, clang also has a -Wtype-limits warning but: * it is not enabled in the kernel at the moment because, contrary to gcc, clang did not include it under -Wextra. * it does not warn if the code results from a macro expansion. So, if activated, it would not cause as much spam as gcc does. * -Wtype-limits is split into four sub-warnings [3] meaning that if it were to be activated, we could select which one to keep. So there is no present need to explicitly disable -Wtype-limits in clang. [1] linux/bits.h: GENMASK_INPUT_CHECK: reduce W=3D2 noise by 31% treewide Link: https://lore.kernel.org/all/20220308141201.2343757-1-mailhol.vincent@= wanadoo.fr/ [2] Warn about "unsigned value that used to be signed against zero" Link: https://lore.kernel.org/all/20250921061337.3047616-1-mailhol@kernel.o= rg/ [3] clang's -Wtype-limits Link: https://clang.llvm.org/docs/DiagnosticsReference.html#wtype-limits Signed-off-by: Vincent Mailhol Reviewed-by: Nicolas Schier --- scripts/Makefile.warn | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/scripts/Makefile.warn b/scripts/Makefile.warn index 68e6fafcb80c..c593ab1257de 100644 --- a/scripts/Makefile.warn +++ b/scripts/Makefile.warn @@ -55,6 +55,9 @@ else KBUILD_CFLAGS +=3D -Wno-main endif =20 +# Too noisy on range checks and in macros handling both signed and unsigne= d. +KBUILD_CFLAGS +=3D -Wno-type-limits + # These result in bogus false positives KBUILD_CFLAGS +=3D $(call cc-option, -Wno-dangling-pointer) =20 @@ -174,7 +177,6 @@ else =20 # The following turn off the warnings enabled by -Wextra KBUILD_CFLAGS +=3D -Wno-missing-field-initializers -KBUILD_CFLAGS +=3D -Wno-type-limits KBUILD_CFLAGS +=3D -Wno-shift-negative-value =20 ifdef CONFIG_CC_IS_CLANG --=20 2.51.2 From nobody Sun Feb 8 08:42:46 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C37CF308F38; Thu, 18 Dec 2025 18:51:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766083883; cv=none; b=Rpldvei83KOyAasnSZZQbAY/foC5hsdV2wfi+Wf2JaLPDbXWrZvTNiBSnk+h4UbP756ZMHI7sSHLKBFGonS4AfvlhHl5A6RUJbay893HKBEXJRRQToYfruW+m6EYqKNe3AQGQdXwEjQSoOf6imtOJGE7Ejt9fx6S0fLj0vWkTao= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766083883; c=relaxed/simple; bh=thjKrci90DOEocQ/rS1/i+0kk0jw1nCk4eiI3odlwtM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=PbTH14HJHEC6yQzhbHsb2W8JneSZsi5o1hI7fktO7+3k9Wh/BqObP/oIT7OlGKXt7ahNXxALgAyz884fVbcwTAXnNsArtdAvCvF1IIu5G3tf1BjYkHfv8SXqsQaoPKU1jf7Mj6V+6R4Q726x0rCqZXaOxHGULoxeRGWLzfKAqe8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E3yxV3VY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="E3yxV3VY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E00DC4CEFB; Thu, 18 Dec 2025 18:51:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766083883; bh=thjKrci90DOEocQ/rS1/i+0kk0jw1nCk4eiI3odlwtM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=E3yxV3VY4hw24X9BzuHN50F7estKLZMSBxdEf8vkYlsezUev+K71iClCx9ajSj89D vXuo0DpMtnBT2r6/NaQponQBdWM7rkpFr5Y9J6hAhuWl8Fpykr7Ak6MvYdoJ7qZ9R2 o8VZKhrsbvrCNbQ865dfDYKgoADMYzlttAFfF484rqgyMrOxvIne8H9PIEMxTNe2yN gfTTDHJd0LhEA2cxkEfydKG/XLAU790laxmMMmMu1bGCWeA/X1uYGli3K0vfAQW57m CL2EHISIf+epUVFJWnLT3cfwfnV3wpH2VmdXsXuL8uTCfx1mWfTBvU8EQ/cJe1/1ob KC6nMh8XtzM2Q== From: Vincent Mailhol Date: Thu, 18 Dec 2025 19:50:02 +0100 Subject: [PATCH 2/2] kbuild: cleanup local -Wno-type-limits exceptions Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251218-remove_wtype-limits-v1-2-735417536787@kernel.org> References: <20251218-remove_wtype-limits-v1-0-735417536787@kernel.org> In-Reply-To: <20251218-remove_wtype-limits-v1-0-735417536787@kernel.org> To: Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Chris Mason , David Sterba Cc: Linus Torvalds , linux-kbuild@vger.kernel.org, linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, dri-devel@lists.freedesktop.org, linux-btrfs@vger.kernel.org, Vincent Mailhol X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1306; i=mailhol@kernel.org; h=from:subject:message-id; bh=thjKrci90DOEocQ/rS1/i+0kk0jw1nCk4eiI3odlwtM=; b=owGbwMvMwCV2McXO4Xp97WbG02pJDJkuvuJ8x/mLPlRs/htqPvPzRfW4F6uZr5fOYqyt/lSva l7HZqHWMZGFQYyLwVJMkWVZOSe3Qkehd9ihv5Ywc1iZQIZIizQwAAELA19uYl6pkY6Rnqm2oZ6h oQ6QycDFKQBTfaiLkWHiwaMMpQddj6e7v/h6JG8Ca3m+bHoTB2/1tRbpJ2ucF0owMny+teOPMsP BbUsmcqQ9nLXVYcqjdI1lrFqLr8/UczhkYM4IAA== X-Developer-Key: i=mailhol@kernel.org; a=openpgp; fpr=ED8F700574E67F20E574E8E2AB5FEB886DBB99C2 Now that -Wno-type-limits is globally deactivated, there is no need for local exceptions anymore. Signed-off-by: Vincent Mailhol Acked-by: David Sterba Reviewed-by: Nicolas Schier --- drivers/gpu/drm/Makefile | 1 - fs/btrfs/Makefile | 1 - 2 files changed, 2 deletions(-) diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 0e1c668b46d2..b879a60ca79a 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -22,7 +22,6 @@ subdir-ccflags-y +=3D $(call cc-option, -Wstringop-trunca= tion) # The following turn off the warnings enabled by -Wextra ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),) subdir-ccflags-y +=3D -Wno-missing-field-initializers -subdir-ccflags-y +=3D -Wno-type-limits subdir-ccflags-y +=3D -Wno-shift-negative-value endif ifeq ($(findstring 3, $(KBUILD_EXTRA_WARN)),) diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile index 743d7677b175..40bc2f7e6f6b 100644 --- a/fs/btrfs/Makefile +++ b/fs/btrfs/Makefile @@ -17,7 +17,6 @@ subdir-ccflags-y +=3D $(condflags) # The following turn off the warnings enabled by -Wextra subdir-ccflags-y +=3D -Wno-missing-field-initializers subdir-ccflags-y +=3D -Wno-sign-compare -subdir-ccflags-y +=3D -Wno-type-limits subdir-ccflags-y +=3D -Wno-shift-negative-value =20 obj-$(CONFIG_BTRFS_FS) :=3D btrfs.o --=20 2.51.2