From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (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 B7D4C478E57; Thu, 6 Aug 2026 17:56:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786039016; cv=none; b=BWebRvoXun/H00aWZdfv5WfsazkD9wf/iCuPWvR6H2cU8ZXQACTEuvEf5Lhw3ZrQstchXoM9YCMTyrcRR4cYESL+i3W8InugHGed7Fm44nqXIFqonFUgES5Du3JQPJVTR+j8XvMSynpMH0TqDLahKlalpvF1dRL2BjE3XDAJfMY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786039016; c=relaxed/simple; bh=3RYQswQOUCpHxdifoM5pD2Uy/DDMtixSFygsWBINfwU=; h=From:To:Cc:MIME-Version:Content-Type:Subject:In-Reply-To: References:Date:Message-ID; b=ZmxDO2Xx/xqfES40qmlpxllzYl1/zhRFN6velW1y+DTXtv9AySWKyYV+nx+ZDuiAHG/kLb42YQJZ9yMUyrmFwdJzbce0iKj1vjX3boJnpMnLzh26wJRQSYN90wc0uOGUkTgMCEQqqoj6QcYEa6Y9s8xxcTi/EIPDb7RMZbt+GFE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=oDY4k7Cj; arc=none smtp.client-ip=198.175.65.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="oDY4k7Cj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1786039014; x=1817575014; h=from:to:cc:mime-version:subject:in-reply-to:references: date:message-id; bh=3RYQswQOUCpHxdifoM5pD2Uy/DDMtixSFygsWBINfwU=; b=oDY4k7Cj6AOexLz4SnlC7wRmzLKqiaLhFX4IkfsFTu50bx2aDJbcaD7f Ux5xgELB+qY4SLQcmmbiu5FOrgJeURM5plQgJs4wmws64U/pthdKGE4QJ U9ihH5NWVAw5d0thjUi7ssl8hxJHluyPq6aDIrHd7yU4m8/2CXn7tlYzx Am1pCDI+CJJlMeEefbK/4aTZwA5w8TBG8pymQ+WOKrZYoq/JRPHQoDbZP CxafVTtHPDLIVZQVKx+FmNDP9enQF1CR/kFgGfDwiyY2xeWXiCZqfQrqC Jv5luq2yb4WNPYwXd/hQ+eqmCO04QIG897B5KQLaK0NQyAaJ+gZf1Lk0Y g==; X-CSE-ConnectionGUID: mdtXtHdqQIKwb53X7JOwpw== X-CSE-MsgGUID: 0hNMY11SRTapLWUkiMZm5Q== X-IronPort-AV: E=McAfee;i="6800,10657,11867"; a="109437618" X-IronPort-AV: E=Sophos;i="6.25,208,1779174000"; d="scan'208";a="109437618" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Aug 2026 10:56:53 -0700 X-CSE-ConnectionGUID: mVgShsRsSvSs83sqrakKdQ== X-CSE-MsgGUID: YY53XFK6T+mQV6Wsj0e1UQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,208,1779174000"; d="scan'208";a="259558973" Received: from vcostago-desk1.jf.intel.com (HELO vcostago-desk1) ([10.88.27.144]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Aug 2026 10:56:53 -0700 From: Vinicius Costa Gomes To: Jack Wang <163wangjack@gmail.com>, Jamal Hadi Salim , Jiri Pirko , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org Cc: Jack Wang <163wangjack@gmail.com>, Simon Horman , linux-kernel@vger.kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCH] net/sched: cbs: perform rate conversions in signed 64-bit arithmetic In-Reply-To: <20260806155253.50252-1-163wangjack@gmail.com> References: <20260806155253.50252-1-163wangjack@gmail.com> Date: Thu, 06 Aug 2026 10:56:52 -0700 Message-ID: <87cxvv2kuz.fsf@intel.com> Jack Wang <163wangjack@gmail.com> writes: > cbs_set_port_rate() and cbs_change() multiply link rates and slope values > by BYTES_PER_KBIT, an unsigned long constant. On 32-bit architectures, > the multiplications therefore take place in 32-bit unsigned arithmetic > before the results are assigned to s64 fields. > > For port rates above approximately 34.36 Gbit/s this wraps port_rate. > The same conversion turns a negative sendslope into a large positive > value, reversing the CBS credit adjustment. This affects software CBS; > port_rate is also refreshed on NETDEV_UP and NETDEV_CHANGE notifications. > > Cast the first operand of each multiplication to s64 so all intermediate > operations use signed 64-bit arithmetic and preserve the value's sign on > every architecture. > > Fixes: 585d763af09c ("net/sched: Introduce Credit Based Shaper (CBS) qdisc") > Fixes: 397006ba5d918 ("net/sched: cbs: Fix integer overflow in cbs_set_port_rate()") > > Signed-off-by: Jack Wang <163wangjack@gmail.com> > --- Acked-by: Vinicius Costa Gomes Cheers, -- Vinicius