From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1D8DC352A4 for ; Mon, 10 Feb 2020 20:40:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B021F2082F for ; Mon, 10 Feb 2020 20:40:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727437AbgBJUkL (ORCPT ); Mon, 10 Feb 2020 15:40:11 -0500 Received: from mga09.intel.com ([134.134.136.24]:46762 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727331AbgBJUkK (ORCPT ); Mon, 10 Feb 2020 15:40:10 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Feb 2020 12:40:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,426,1574150400"; d="scan'208";a="347123723" Received: from tthayer-hp-z620.an.intel.com (HELO [10.122.105.146]) ([10.122.105.146]) by fmsmga001.fm.intel.com with ESMTP; 10 Feb 2020 12:40:09 -0800 Reply-To: thor.thayer@linux.intel.com Subject: Re: [PATCH] i2c: altera: Use 64-bit arithmetic instead of 32-bit To: "Gustavo A. R. Silva" Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200210192656.GA8412@embeddedor> From: Thor Thayer Message-ID: Date: Mon, 10 Feb 2020 14:42:16 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200210192656.GA8412@embeddedor> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/10/20 1:26 PM, Gustavo A. R. Silva wrote: > Add suffix ULL to constant 300 in order to avoid a potential integer > overflow and give the compiler complete information about the proper > arithmetic to use. Notice that this constant is being used in a context > that expects an expression of type u64, but it's currently evaluated > using 32-bit arithmetic. > > Addresses-Coverity: 1458369 ("Unintentional integer overflow") > Fixes: 0560ad576268 ("i2c: altera: Add Altera I2C Controller driver") > Signed-off-by: Gustavo A. R. Silva > --- > drivers/i2c/busses/i2c-altera.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-altera.c b/drivers/i2c/busses/i2c-altera.c > index 5255d3755411..526f453f0ff7 100644 > --- a/drivers/i2c/busses/i2c-altera.c > +++ b/drivers/i2c/busses/i2c-altera.c > @@ -171,7 +171,8 @@ static void altr_i2c_init(struct altr_i2c_dev *idev) > /* SCL Low Time */ > writel(t_low, idev->base + ALTR_I2C_SCL_LOW); > /* SDA Hold Time, 300ns */ > - writel(div_u64(300 * clk_mhz, 1000), idev->base + ALTR_I2C_SDA_HOLD); > + writel(div_u64(300ULL * clk_mhz, 1000), > + idev->base + ALTR_I2C_SDA_HOLD); > > /* Mask all master interrupt bits */ > altr_i2c_int_enable(idev, ALTR_I2C_ALL_IRQ, false); > Thank you. Reviewed-by: Thor Thayer