From mboxrd@z Thu Jan 1 00:00:00 1970 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 144342D0607; Thu, 1 Jan 2026 15:10:44 +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=1767280245; cv=none; b=M3yQ5+MRD7swcLQ8s+V2thOGVHoEO9O9w5oTaZ83oi5j8J2QgVbwx9pPW/XTTUBcaMRbPdAXeqfLF2Yi1dhjRS0G7Olq+3vICVPT0kAcdmppVtXRj+hRyIM3lXgW7Av+xhmPXgSeAyOMwS+p/DmwqBpu9Tz57CqeN5e9ByVzRDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767280245; c=relaxed/simple; bh=Hsig7qMqvEeHA2BrqJU8yUjptGfEzJylfzi+6cxd0ug=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UAhNo7V/rG0WLtdds9TziWGsIBNfm26Du0BEaHk95s+qRD0vbLhfKhKrUO741IFoYWS9J9h7hc+3lFlyQBGLEyqVGO4KWruzjqPyw6/3ubyQiQfkLwyynhzi4G+2jIVzJwqDHM4tRY/cj+zCuNHxVbKZZovK7Dbl02mRvZGILJU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qPtWOjyC; 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="qPtWOjyC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79F6FC4CEF7; Thu, 1 Jan 2026 15:10:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767280244; bh=Hsig7qMqvEeHA2BrqJU8yUjptGfEzJylfzi+6cxd0ug=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=qPtWOjyCCVoSbrgS2By+iC+tj/ZvF1ekBhMhWNic+UdxunQzjzXupcVisCiQw0WRF NfSFKZz3L6tMfm8jaTLqv9GRWlQOL6xHpYie5zd8kkt+JMjfhzXY1jmpw/Q4DpBLlP LExnq3NxIvOMw1FV0XWjOJzHC+6/SZimsEdhk6znVGM2FLupF4/j+R3Zfb/gRIGx6m cHTfRSzxvhQlZZ/JDvl7RU+A01rNwqRhEzPduJideLi32KeSMEyc6JOB+VeSwoe2GU cORzzmAL15U743KQLWeY8vsDe6JTTeSrK8tHZY16Q/5hg8/0vTkrOJyxvGwfccZQqF Qyd0UTVRBtdog== Message-ID: Date: Thu, 1 Jan 2026 16:10:36 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/3] overflow: Remove is_non_negative() and is_negative() 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 , Kees Cook , "Gustavo A. R. Silva" 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, linux-hardening@vger.kernel.org, kernel test robot References: <20251220-remove_wtype-limits-v3-0-24b170af700e@kernel.org> <20251220-remove_wtype-limits-v3-3-24b170af700e@kernel.org> From: Vincent Mailhol Content-Language: en-US Autocrypt: addr=mailhol@kernel.org; keydata= xjMEZluomRYJKwYBBAHaRw8BAQdAf+/PnQvy9LCWNSJLbhc+AOUsR2cNVonvxhDk/KcW7FvN JFZpbmNlbnQgTWFpbGhvbCA8bWFpbGhvbEBrZXJuZWwub3JnPsKZBBMWCgBBFiEE7Y9wBXTm fyDldOjiq1/riG27mcIFAmdfB/kCGwMFCQp/CJcFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcC F4AACgkQq1/riG27mcKBHgEAygbvORJOfMHGlq5lQhZkDnaUXbpZhxirxkAHwTypHr4A/joI 2wLjgTCm5I2Z3zB8hqJu+OeFPXZFWGTuk0e2wT4JzjgEZx4y8xIKKwYBBAGXVQEFAQEHQJrb YZzu0JG5w8gxE6EtQe6LmxKMqP6EyR33sA+BR9pLAwEIB8J+BBgWCgAmFiEE7Y9wBXTmfyDl dOjiq1/riG27mcIFAmceMvMCGwwFCQPCZwAACgkQq1/riG27mcJU7QEA+LmpFhfQ1aij/L8V zsZwr/S44HCzcz5+jkxnVVQ5LZ4BANOCpYEY+CYrld5XZvM8h2EntNnzxHHuhjfDOQ3MAkEK In-Reply-To: <20251220-remove_wtype-limits-v3-3-24b170af700e@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 20/12/2025 at 12:02, Vincent Mailhol wrote: > The is_non_negative() and is_negative() function-like macros just > exist as a workaround to silence the -Wtype-limits warning. Now that > this warning is disabled, those two macros have lost their raison > d'être. Remove them. > > This reverts commit dc7fe518b049 ("overflow: Fix -Wtype-limits > compilation warnings"). > > Suggested-by: Nicolas Schier > Link: https://lore.kernel.org/all/aUT_yWin_xslnOFh@derry.ads.avm.de > Signed-off-by: Vincent Mailhol So at the end, this patch got five kernel test robot reports: https://lore.kernel.org/all/202512221735.mRV4BZqB-lkp@intel.com/ https://lore.kernel.org/all/202512230342.Lgha2HGH-lkp@intel.com/ https://lore.kernel.org/all/202512251340.UApIFw9R-lkp@intel.com/ https://lore.kernel.org/all/202512271618.33YepxDC-lkp@intel.com/ https://lore.kernel.org/all/202512280906.wt7UNpya-lkp@intel.com/ All these are the same smatch warning just triggered from a different place. I think it is still too early to undo that workaround in include/linux/overflow.h, otherwise developers would be getting that smatch report too often. I will send a v4 in which I will drop this patch. This basically means that the v4 is a revert to v1... > --- > Changelog: > > v1 -> v2: new patch > --- > include/linux/overflow.h | 10 ++-------- > 1 file changed, 2 insertions(+), 8 deletions(-) > > diff --git a/include/linux/overflow.h b/include/linux/overflow.h > index 736f633b2d5f..ab142d60c6b5 100644 > --- a/include/linux/overflow.h > +++ b/include/linux/overflow.h > @@ -36,12 +36,6 @@ > #define __type_min(T) ((T)((T)-type_max(T)-(T)1)) > #define type_min(t) __type_min(typeof(t)) > > -/* > - * Avoids triggering -Wtype-limits compilation warning, > - * while using unsigned data types to check a < 0. > - */ > -#define is_non_negative(a) ((a) > 0 || (a) == 0) > -#define is_negative(a) (!(is_non_negative(a))) > > /* > * Allows for effectively applying __must_check to a macro so we can have > @@ -201,9 +195,9 @@ static inline bool __must_check __must_check_overflow(bool overflow) > typeof(d) _d = d; \ > unsigned long long _a_full = _a; \ > unsigned int _to_shift = \ > - is_non_negative(_s) && _s < 8 * sizeof(*d) ? _s : 0; \ > + _s >= 0 && _s < 8 * sizeof(*d) ? _s : 0; \ > *_d = (_a_full << _to_shift); \ > - (_to_shift != _s || is_negative(*_d) || is_negative(_a) || \ > + (_to_shift != _s || *_d < 0 || _a < 0 || \ > (*_d >> _to_shift) != _a); \ > })) > > Yours sincerely, Vincent Mailhol