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 2CE1AC5CFE7 for ; Mon, 9 Jul 2018 16:40:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7A4C20844 for ; Mon, 9 Jul 2018 16:40:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7A4C20844 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 S933634AbeGIQk2 (ORCPT ); Mon, 9 Jul 2018 12:40:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43168 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933009AbeGIQk1 (ORCPT ); Mon, 9 Jul 2018 12:40:27 -0400 Received: from smtp.corp.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0FFC3C057FA1; Mon, 9 Jul 2018 16:40:27 +0000 (UTC) Received: from [10.10.122.164] (ovpn-122-164.rdu2.redhat.com [10.10.122.164]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8CFA5300193B; Mon, 9 Jul 2018 16:40:25 +0000 (UTC) Subject: Re: [PATCH v3 3/3] uio: fix crash after the device is unregistered To: Xiubo Li , gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org References: <1530845836-49101-1-git-send-email-xiubli@redhat.com> <1530845836-49101-4-git-send-email-xiubli@redhat.com> <5B3FBBF1.9080902@redhat.com> <434b1b7c-604d-a446-b73a-8de7a50817c5@redhat.com> Cc: hamish.martin@alliedtelesis.co.nz, jannh@google.com, pkalever@redhat.com, pkarampu@redhat.com, atumball@redhat.com, sabose@redhat.com From: Mike Christie Message-ID: <5B438FF3.4040707@redhat.com> Date: Mon, 9 Jul 2018 11:40:19 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <434b1b7c-604d-a446-b73a-8de7a50817c5@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Mon, 09 Jul 2018 16:40:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/06/2018 08:47 PM, Xiubo Li wrote: > 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. Before tcmu_destroy_device is called LIO will have stopped new IO and waited for outstanding IO to be completed, so it would never be called after uio_unregister_device. If it does, it's a bug in LIO.