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=-0.8 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 A42DEC3279B for ; Sat, 7 Jul 2018 01:47:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4EFD72249E for ; Sat, 7 Jul 2018 01:47:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4EFD72249E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932642AbeGGBrV (ORCPT ); Fri, 6 Jul 2018 21:47:21 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:42290 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753816AbeGGBrU (ORCPT ); Fri, 6 Jul 2018 21:47:20 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E44A94022414; Sat, 7 Jul 2018 01:47:19 +0000 (UTC) Received: from [10.72.12.18] (ovpn-12-18.pek2.redhat.com [10.72.12.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EC3822026D68; Sat, 7 Jul 2018 01:47:15 +0000 (UTC) Subject: Re: [PATCH v3 3/3] uio: fix crash after the device is unregistered To: Mike Christie , gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org Cc: hamish.martin@alliedtelesis.co.nz, jannh@google.com, pkalever@redhat.com, pkarampu@redhat.com, atumball@redhat.com, sabose@redhat.com References: <1530845836-49101-1-git-send-email-xiubli@redhat.com> <1530845836-49101-4-git-send-email-xiubli@redhat.com> <5B3FBBF1.9080902@redhat.com> From: Xiubo Li Message-ID: <434b1b7c-604d-a446-b73a-8de7a50817c5@redhat.com> Date: Sat, 7 Jul 2018 09:47:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.0 MIME-Version: 1.0 In-Reply-To: <5B3FBBF1.9080902@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Sat, 07 Jul 2018 01:47:19 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Sat, 07 Jul 2018 01:47:19 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'xiubli@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/7/7 2:58, Mike Christie wrote: > On 07/05/2018 09:57 PM, xiubli@redhat.com wrote: >> void uio_event_notify(struct uio_info *info) >> { >> - struct uio_device *idev = info->uio_dev; >> + struct uio_device *idev; >> + >> + if (!info) >> + return; >> + >> + idev = info->uio_dev; >> > For this one too, I am not sure if it is needed. > > uio_interrupt -> uio_event_notify. See other mail. > > driver XYZ -> uio_event_notify. I think drivers need to handle this and > set some bits and/or perform some cleanup to make sure they are not > calling uio_event_notify after it has called uio_unregister_device. The > problem with the above test is if they do not they could have called > uio_unregister_device right after the info test so you could still hit > the problem. When we are tcmu_destroy_device(), if the netlink notify event to userspace is not successful then the TCMU will call the uio unregister, which will set the idev->info = NULL, without close and deleting the device in userspace. But the TCMU could still queue cmds to the ring buffer, then the uio_event_notify will be called. For this case only when using idev->info it would happen. And currently there is no need to check this, I will remove it for now. Thanks, BRs