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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 C131EC43387 for ; Tue, 15 Jan 2019 01:48:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 925DF2063F for ; Tue, 15 Jan 2019 01:48:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727742AbfAOBsM (ORCPT ); Mon, 14 Jan 2019 20:48:12 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:17141 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726769AbfAOBsM (ORCPT ); Mon, 14 Jan 2019 20:48:12 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id F1A36ACA076B08F62F36; Tue, 15 Jan 2019 09:48:09 +0800 (CST) Received: from [127.0.0.1] (10.57.115.182) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.408.0; Tue, 15 Jan 2019 09:48:02 +0800 Subject: Re: [PATCH rdma-rc 1/3] RDMA/hns: Fix the Oops during rmmod or insmod ko when reset occurs To: Jason Gunthorpe References: <1547128663-69220-1-git-send-email-xavier.huwei@huawei.com> <1547128663-69220-2-git-send-email-xavier.huwei@huawei.com> <20190111213411.GA22310@ziepe.ca> <5C399D73.5000902@huawei.com> <20190114220655.GD1208@ziepe.ca> CC: , , , , , , , , , From: "Wei Hu (Xavier)" Message-ID: <5C3D3BD1.4000508@huawei.com> Date: Tue, 15 Jan 2019 09:48:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20190114220655.GD1208@ziepe.ca> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.57.115.182] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/1/15 6:06, Jason Gunthorpe wrote: > On Sat, Jan 12, 2019 at 03:55:31PM +0800, Wei Hu (Xavier) wrote: >> >> On 2019/1/12 5:34, Jason Gunthorpe wrote: >>> On Thu, Jan 10, 2019 at 09:57:41PM +0800, Wei Hu (Xavier) wrote: >>>> + /* Check the status of the current software reset process, if in >>>> + * software reset process, wait until software reset process finished, >>>> + * in order to ensure that reset process and this function will not call >>>> + * __hns_roce_hw_v2_uninit_instance at the same time. >>>> + * If a timeout occurs, it indicates that the network subsystem has >>>> + * encountered a serious error and cannot be recovered from the reset >>>> + * processing. >>>> + */ >>>> + if (ops->ae_dev_resetting(handle)) { >>>> + dev_warn(dev, "Device is busy in resetting state. waiting.\n"); >>>> + end = msecs_to_jiffies(HNS_ROCE_V2_RST_PRC_MAX_TIME) + jiffies; >>>> + while (ops->ae_dev_resetting(handle) && >>>> + time_before(jiffies, end)) >>>> + msleep(20); >>> Really? Does this have to be so ugly? Why isn't there just a simple >>> lock someplace that is held during reset? >>> >>> I'm skeptical that all this strange looking stuff is properly locked >>> and concurrency safe. >> Hi, Jason >> >> The hns3 NIC driver notifies the hns RoCE driver to perform >> reset related processing by calling the .reset_notify() interface >> registered by the RoCE driver. >> >> There is a constraint on the hip08 chip, the NIC driver needs to >> stop the flow before hardware startup reset, otherwise the chip >> may hang up. >> >> We've also thought about using locks, but found using locks can >> lead to more serious problems because of that restriction of the >> chip. >> If using locks here, reset processing may wait for uninstallation >> to complete, this may lead that NIC driver fails to stop the flow >> in time in the reset process, thus causing the chip to hang up. > If you are sleeping then I'm sure a lock can be used instead, how > would it be any different? Hi, Jason If using locks here, reset process may wait until uninstallation to complete, it may trigger the chip constraint, causing chip to hang up. But if using sleeping here, there will notthe case that reset process wait until uninstallation to complete, then will not trigger the chip constraint. Thanks reset process lock .... unlock uninitallation lock ... unlock Regards Xavier > Jason > > . >