From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793585859; b=hD5w7MJZfgsexSBxKvxtAQOEu5A7Xgcp9YwJTfSymbzsjbBn2nRTdZ32sT2spBzLps1N OwYiifevgcAdhbySi17ZsQxkBkAyADep+g2vYUFWVxy9nPsrcZzt95IqSdul8UB6ZrQJM CiPWwOsE8GSWNwnLWoBmZch3GEHLUt1zpAqMxbj52qPPIi4+CEKNLbbNR/rbfKyyPQoKA yMp3bYpEUKaYQUGDlBkNWVcMQ5WjFvCzi+vQ5R+7CfDaAKkt2TFhOXpW9hvNOhGXGOr4O sAed9P3kPyJiH1UWooT4q6wXPOQhAgTH4bvzFWeCVe/MdBSdMwqRsXU0ET959+Rp42A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793585859; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=n6Qbek9LA5EmGsWJy4g+zEUBaCCV0A3uVN7HKVa0vZ4=; b=ynntxB2BM+Xz3nxSE3ql4vB3h67xc8s3fbPV8gbdfzTXj2mWsBK2Hvn6q4nRiBQDp4ML 6jK2mjbOzBUesOlzfbdGTJ/nkMo7QUgMT4g01qKcJDWa2zfZUGKr0Vp3itRyHGfMW31qL IXl10Jt008wtn3kGhIhNQtIpagOFRt3HnfSCWoWcFGM4bfRIFRoG8q2QZ/cGwbnMXxyxB 0vkaGK8RZwpWCbinQPNj/wUZKwUEIhPczTK9+N+0Dx5qcTu4kwFwOBwMQ/BfPUHovBFs8 YYJSJM7xDpQl7YpejfMPpV/Xcpw/r96uY+i5q8pKjyLmUiroiX+UJTre7YwLXA40vwg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="R/jU1d6F"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA2B4606A324 for ; Mon, 2 Nov 2026 02:17:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=R/jU1d6F Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56C641F000C1; Mon, 2 Nov 2026 02:17:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793585858; bh=n6Qbek9LA5EmGsWJy4g+zEUBaCCV0A3uVN7HKVa0vZ4=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=R/jU1d6F3jrSebr69oqkyU1C8CClWgpwwHKO/bOlV/OE3sWQrt9BriAcsf7q2m968 qLkDqvjfEVjxtbotwFU1faky/vqL9kbh+oXRKJQASp2D7557UKMcdsnyklb2mT89oz j95mn9igTWhXz8KyxCq5FQHBMxPMb3iYG6lrn19EiLz4AA4SKS914iaL9JFiX9y6Y8 EWjRWIsKmM8uRSa1Ww/2J6wGagmjoGEPkmXNsMPvmeHbTVtbkgFmM7s5SKiiRTY/9Q mlZNqRhc4rHFx7Co45Q1CLQPZG+qLIblCWorXFP14XT1lTzr/GRcWv8a1YQq+/TGBs WFvxTwW2FFIgA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 04/10] leds: rgb: ktd202x: Fix a division by zero with long blinks Reply-To: sashiko-reviews@lists.linux.dev To: "Joseph Telaak" Cc: linux-leds@vger.kernel.org, lee@kernel.org In-Reply-To: <20261101-ktd202x-et6326-v1-4-eb51eddad08c@telaak.dev> References: <20261101-ktd202x-et6326-v1-0-eb51eddad08c@telaak.dev> <20261101-ktd202x-et6326-v1-4-eb51eddad08c@telaak.dev> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 02 Nov 2026 02:17:37 +0000 X-Mailing-List: linux-leds@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > From: Joseph Telaak >=20 > blink_set() works out the on time as delay_on * 256 / (delay_on + > delay_off) in unsigned long, with delays straight from the timer > trigger's sysfs files: >=20 > - when the two delays add up to exactly 2^32 on 32 bit, or 2^64 on > 64 bit, the sum wraps to 0 and the kernel divides by zero, for > example with "echo 2147483648" into both delay_on and delay_off. > That oopses on x86 and gives an arbitrary result on MIPS and arm64. > - on 32 bit the product already overflows once delay_on is above about > 4.6 hours, and a sum that wraps sets the wrong period, so long blinks > get an arbitrary duty cycle >=20 > Saturate the sum, and compute the on time with mul_u64_u64_div_u64(). >=20 > Fixes: 0ebdb7210943 ("leds: Add ktd202x driver") > Cc: stable@vger.kernel.org > Assisted-by: Claude:claude-opus-5-5 > Signed-off-by: Joseph Telaak Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261101-ktd202x-et= 6326-v1-0-eb51eddad08c@telaak.dev?part=3D4