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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429c13e03d0sm4429347f8f.26.2025.10.31.09.17.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 09:17:10 -0700 (PDT) Date: Fri, 31 Oct 2025 16:17:08 +0000 From: David Laight To: Oleg Nesterov Cc: Andrew Morton , linux-kernel@vger.kernel.org, u.kleine-koenig@baylibre.com, Nicolas Pitre , Peter Zijlstra , Biju Das , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Li RongQing , Yu Kuai , Khazhismel Kumykov , Jens Axboe , x86@kernel.org Subject: Re: [PATCH v4 next 0/9] Implement mul_u64_u64_div_u64_roundup() Message-ID: <20251031161708.312343f8@pumpkin> In-Reply-To: <20251031135255.GA22251@redhat.com> References: <20251029173828.3682-1-david.laight.linux@gmail.com> <20251031135255.GA22251@redhat.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 Fri, 31 Oct 2025 14:52:56 +0100 Oleg Nesterov wrote: > On 10/29, David Laight wrote: > > > > The pwm-stm32.c code wants a 'rounding up' version of mul_u64_u64_div_u64(). > > This can be done simply by adding 'divisor - 1' to the 128bit product. > > Implement mul_u64_add_u64_div_u64(a, b, c, d) = (a * b + c)/d based on the > > existing code. > > Define mul_u64_u64_div_u64(a, b, d) as mul_u64_add_u64_div_u64(a, b, 0, d) and > > mul_u64_u64_div_u64_roundup(a, b, d) as mul_u64_add_u64_div_u64(a, b, d-1, d). > > Sorry for the noise. Can't review due to the lack of knowledge. > But this reminds me... What about > > [PATCH v3 1/2] x86/math64: handle #DE in mul_u64_u64_div_u64() > https://lore.kernel.org/all/20250815164055.GA13444@redhat.com > > ? > > should I resend it once again or we don't care? I'd remembered that as well. I'll do a new version of that on top as a separate patch. Probably when this set has been merged further. David