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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4324493fda5sm1364377f8f.17.2025.12.17.14.31.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 14:31:57 -0800 (PST) Date: Wed, 17 Dec 2025 22:31:55 +0000 From: David Laight To: Jonathan Cameron Cc: Yury Norov , Rasmus Villemoes , , , Geert Uytterhoeven , Alexandre Belloni , Crt Mori , Richard Genoud , "Andy Shevchenko" , Luo Jie , Peter Zijlstra , Jakub Kicinski , , "David S . Miller" , "Mika Westerberg" , Andreas Noever , Yehezkel Bernat , "Nicolas Frattaroli" Subject: Re: [PATCH v2 08/16] bitfield: Simplify __BF_FIELD_CHECK_REG() Message-ID: <20251217223155.52249236@pumpkin> In-Reply-To: <20251217102618.0000465f@huawei.com> References: <20251212193721.740055-1-david.laight.linux@gmail.com> <20251212193721.740055-9-david.laight.linux@gmail.com> <20251217102618.0000465f@huawei.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) 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=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 17 Dec 2025 10:26:18 +0000 Jonathan Cameron wrote: > On Fri, 12 Dec 2025 19:37:13 +0000 > david.laight.linux@gmail.com wrote: > > > From: David Laight > > > > Simplify the check for 'reg' being large enough to hold 'mask' using > > sizeof (reg) rather than a convoluted scheme to generate an unsigned > > type the same size as 'reg'. > > > > Signed-off-by: David Laight > Hi David, > > Just one really trivial comment inline. Feel free to ignore. > > Jonathan > > > --- > > @@ -75,8 +59,8 @@ > > }) > > > > #define __BF_FIELD_CHECK_REG(mask, reg, pfx) \ > > - BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) > \ > > - __bf_cast_unsigned(reg, ~0ull), \ > > + BUILD_BUG_ON_MSG((mask) + 0U + 0UL + 0ULL > \ > > + ~0ULL >> (64 - 8 * sizeof (reg)), \ > > Trivial. sizeof(reg) is much more comment syntax in kernel code. (common) Hmm. sizeof is an operator not a function. Its argument is either a variable/expression or a bracketed type (I don't usually put variables in brackets). So 'sizeof(reg)' is nearly as bad as 'return(reg)'. David > > > pfx "type of reg too small for mask") > > > > #define __BF_FIELD_CHECK(mask, reg, val, pfx) \ >