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[73.105.0.253]) by smtp.gmail.com with ESMTPSA id 00721157ae682-787b15d6379sm9121887b3.45.2025.11.06.08.01.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Nov 2025 08:01:40 -0800 (PST) Date: Thu, 6 Nov 2025 11:01:39 -0500 From: Yury Norov To: Andy Shevchenko Cc: Geert Uytterhoeven , Michael Turquette , Stephen Boyd , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Giovanni Cabiddu , Herbert Xu , David Miller , Linus Walleij , Bartosz Golaszewski , Joel Stanley , Andrew Jeffery , Crt Mori , Jonathan Cameron , Lars-Peter Clausen , Jacky Huang , Shan-Chun Hung , Rasmus Villemoes , Jaroslav Kysela , Takashi Iwai , Johannes Berg , Jakub Kicinski , Alex Elder , David Laight , Vincent Mailhol , Jason Baron , Borislav Petkov , Tony Luck , Michael Hennerich , Kim Seer Paller , David Lechner , Nuno =?iso-8859-1?Q?S=E1?= , Andy Shevchenko , Richard Genoud , Cosmin Tanislav , Biju Das , Jianping Shen , Nathan Chancellor , Nick Desaulniers , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-renesas-soc@vger.kernel.org, linux-crypto@vger.kernel.org, linux-edac@vger.kernel.org, qat-linux@intel.com, linux-gpio@vger.kernel.org, linux-aspeed@lists.ozlabs.org, linux-iio@vger.kernel.org, linux-sound@vger.kernel.org, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 12/26] bitfield: Add less-checking __FIELD_{GET,PREP}() Message-ID: References: Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu, Nov 06, 2025 at 04:44:31PM +0200, Andy Shevchenko wrote: > On Thu, Nov 06, 2025 at 02:34:00PM +0100, Geert Uytterhoeven wrote: > > The BUILD_BUG_ON_MSG() check against "~0ull" works only with "unsigned > > (long) long" _mask types. For constant masks, that condition is usually > > met, as GENMASK() yields an UL value. The few places where the > > constant mask is stored in an intermediate variable were fixed by > > changing the variable type to u64 (see e.g. [1] and [2]). > > > > However, for non-constant masks, smaller unsigned types should be valid, > > too, but currently lead to "result of comparison of constant > > 18446744073709551615 with expression of type ... is always > > false"-warnings with clang and W=1. > > > > Hence refactor the __BF_FIELD_CHECK() helper, and factor out > > __FIELD_{GET,PREP}(). The later lack the single problematic check, but > > are otherwise identical to FIELD_{GET,PREP}(), and are intended to be > > used in the fully non-const variants later. > > > > [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in > > HWM_FIELD_PREP()") > > [2] commit cfd6fb45cfaf46fa ("crypto: ccree - avoid out-of-range > > warnings from clang") > > > Also can be made as > > Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1] > > The positive effect that one may click that on Git Web. > Ideally, of course, would be an additional parses on Git Web kernel.org uses to > parse that standard "commit ...()" notation to add the respective HREF link. Those flying over Atlantic or cruising cross Caribbean would disagree. :) > > Signed-off-by: Geert Uytterhoeven > > ... > > > + BUILD_BUG_ON_MSG(__bf_cast_unsigned(mask, mask) > \ > > + __bf_cast_unsigned(reg, ~0ull), \ > > + pfx "type of reg too small for mask") > > Perhaps we may convert this (and others?) to static_assert():s at some point? > > > -- > With Best Regards, > Andy Shevchenko >