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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5723FC433EF for ; Thu, 21 Oct 2021 05:55:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 314E0610FF for ; Thu, 21 Oct 2021 05:55:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229539AbhJUF5t (ORCPT ); Thu, 21 Oct 2021 01:57:49 -0400 Received: from mga18.intel.com ([134.134.136.126]:50047 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229499AbhJUF5t (ORCPT ); Thu, 21 Oct 2021 01:57:49 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10143"; a="215871485" X-IronPort-AV: E=Sophos;i="5.87,168,1631602800"; d="scan'208";a="215871485" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2021 22:55:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,168,1631602800"; d="scan'208";a="444654055" Received: from unknown (HELO [10.239.154.68]) ([10.239.154.68]) by orsmga006.jf.intel.com with ESMTP; 20 Oct 2021 22:55:31 -0700 Subject: Re: [PATCH 2/2] i2c: virtio: fix completion handling To: Vincent Whitchurch , wsa@kernel.org, viresh.kumar@linaro.org Cc: virtualization@lists.linux-foundation.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@axis.com References: <20211019074647.19061-1-vincent.whitchurch@axis.com> <20211019074647.19061-3-vincent.whitchurch@axis.com> From: Jie Deng Message-ID: Date: Thu, 21 Oct 2021 13:55:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211019074647.19061-3-vincent.whitchurch@axis.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 2021/10/19 15:46, Vincent Whitchurch wrote: > The driver currently assumes that the notify callback is only received > when the device is done with all the queued buffers. > > However, this is not true, since the notify callback could be called > without any of the queued buffers being completed (for example, with > virtio-pci and shared interrupts) or with only some of the buffers being > completed (since the driver makes them available to the device in > multiple separate virtqueue_add_sgs() calls). Can the backend driver control the time point of interrupt injection ? I can't think of why the backend has to send an early interrupt. This operation should be avoided in the backend driver if possible. However, this change make sense if early interrupt can't be avoid. > > This can lead to incorrect data on the I2C bus or memory corruption in > the guest if the device operates on buffers which are have been freed by > the driver. (The WARN_ON in the driver is also triggered.) >