From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.15]) (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 3AA2C5452A8; Wed, 16 Sep 2026 15:39:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789573200; cv=none; b=B2A6/808cQeUTMKu4ry4xVAJagOXa6RDSRjlx8+nCkjwlD1oq1lNBble4d90p8bW9nF6OoK0ANulhE6z5zY072Xlmg++EYRJAKGd/WXETPGeVdn+6pzIYQzVNZx385UzD0JhhQZkgg96LlbTUxBOYy9zUIAEXCbM0p8022mPMN0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789573200; c=relaxed/simple; bh=do7fs/RqIazZyqQPcXOJDXYuoCBird5b0yM0GMe8rv8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UpwOpO4XPVETn3Jqd+6W5rekrrGZuKG0WZERHKwZ5Dq2h6HpBwOmX9hSLODigtqL8Mlztx8T7hsffnFJu+hGIsol/neaKXlXWxgMDSLkl/inEdOPZd8WHwrVEghcSQp2aZtLq4IH3d+ULbHmEB22e+Igyr8aLMR89WhU6zZdAac= 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=K3IiCsvi; arc=none smtp.client-ip=198.175.65.15 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="K3IiCsvi" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1789573198; x=1821109198; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=do7fs/RqIazZyqQPcXOJDXYuoCBird5b0yM0GMe8rv8=; b=K3IiCsviL9TPrGqOrMwG7H+VOH3g32ZNcPCrNt8CPyhHi11m6EjtjEeu XXRfDswXa+OjO5cLSr5cp6rxtE2ydKGFj2JyPiQdT66u2xxYiDcU0YVBX PQbV26Pq4izWhUZqeYFcC8oQ+gLL6pq3rDAb7yvbz202/8FTGGNN14ezZ ldiTMnUmotE5P2c3l8tt2lw6ph/zV3rizZo3j9pFUuRVFYqQmLYLN6Rk4 amYohvHVf8BfaKZO0+HqCqVn5kphXGQogye0LhbRcqoVSCyP5Ou419rEj Aqpvfd1vpiK/laLyqL48Mj8rAxwfJrSMqKRId/qIyd24kUE5IRDPNCSdh A==; X-CSE-ConnectionGUID: CudlW9+xS6WQIl3ftGdkVQ== X-CSE-MsgGUID: YdWqhMKBQI6qpH+yz0aqng== X-IronPort-AV: E=McAfee;i="6800,10657,11905"; a="93656710" X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="93656710" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2026 08:39:57 -0700 X-CSE-ConnectionGUID: hKF6xc+KSeSiJwBW663bRQ== X-CSE-MsgGUID: 2yn5LcLKSd+cphrjWLOTJg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,103,1787036400"; d="scan'208";a="272903448" Received: from ettammin-mobl2.ger.corp.intel.com (HELO localhost) ([10.245.244.145]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2026 08:39:54 -0700 Date: Wed, 16 Sep 2026 18:39:52 +0300 From: Andy Shevchenko To: Fabrice Gasnier Cc: Jonathan Cameron , David Lechner , Nuno =?iso-8859-1?Q?S=E1?= , Andy Shevchenko , Maxime Coquelin , Alexandre Torgue , Olivier Moysan , linux-iio@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sashiko , stable@vger.kernel.org Subject: Re: [PATCH v2] iio: adc: stm32-adc: fix possible division by zero in processed channel Message-ID: References: <20260916-adc-fix-div0-v2-1-f702d3ed782c@foss.st.com> <538c8203-3880-47aa-ba4e-014a345b3cb9@foss.st.com> 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-Disposition: inline In-Reply-To: <538c8203-3880-47aa-ba4e-014a345b3cb9@foss.st.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Wed, Sep 16, 2026 at 05:20:48PM +0200, Fabrice Gasnier wrote: > On 9/16/26 16:39, Andy Shevchenko wrote: [ snip ] > > Let's look at the current code in this switch-case > > Thanks for you suggestions ! > > Let's keep in the picture the 'normal' raw case: Ah, an important detail! > case IIO_CHAN_INFO_RAW: > > case IIO_CHAN_INFO_PROCESSED: > > if (!iio_device_claim_direct(indio_dev)) > > return -EBUSY; > > if (chan->type == IIO_VOLTAGE) > > ret = stm32_adc_single_conv(indio_dev, chan, val); > > else > > ret = -EINVAL; > > > > if (mask == IIO_CHAN_INFO_PROCESSED) > > *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val; > > > > iio_device_release_direct(indio_dev); > > return ret; > > > > In the previous version you were trying to keep goto-less approach. > > However in the current state of affairs I don't think the goto is > > too bad (after all we need to backport this to the kernels that may > > not have IIO_DEV_ACQUIRE_DIRECT_MODE() macro). > > > > Also checking 'ret' under another condition seems unusual. > > > > What about > > > > case IIO_CHAN_INFO_PROCESSED: > > if (!iio_device_claim_direct(indio_dev)) > > return -EBUSY; > > if (chan->type == IIO_VOLTAGE) > > ret = stm32_adc_single_conv(indio_dev, chan, val); > > else > > ret = -EINVAL; > > iio_device_release_direct(indio_dev); > > if (ret) > > return ret; > > > > if (*val == 0) > > return -EINVAL; > > So *val == 0 is normally a valid value, for 'normal' raw channels. > > > if (mask == IIO_CHAN_INFO_PROCESSED) > > *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val; > > With you suggestion, moving if (*val == 0) to here should be fine ? Yep. > if (mask == IIO_CHAN_INFO_PROCESSED) { > if (*val == 0) > return -EINVAL; > *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val; > } > > > return 0; > > > > ? (Yes, we leave that line untouched, but we get the change cleaner.) -- With Best Regards, Andy Shevchenko