From patchwork Mon Mar 20 02:36:59 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alex Williamson X-Patchwork-Id: 9632989 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 42A7860326 for ; Mon, 20 Mar 2017 02:37:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 32C6020572 for ; Mon, 20 Mar 2017 02:37:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 278C2205F8; Mon, 20 Mar 2017 02:37:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 85E0526C9B for ; Mon, 20 Mar 2017 02:37:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752908AbdCTChF (ORCPT ); Sun, 19 Mar 2017 22:37:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53670 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752890AbdCTChD (ORCPT ); Sun, 19 Mar 2017 22:37:03 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 062FA83F42; Mon, 20 Mar 2017 02:37:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 062FA83F42 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=alex.williamson@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 062FA83F42 Received: from gimli.home (ovpn-117-7.phx2.redhat.com [10.3.117.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id ACBAC18A7F; Mon, 20 Mar 2017 02:37:00 +0000 (UTC) Subject: [PATCH] vfio: Rework group release notifier warning From: Alex Williamson To: alex.williamson@redhat.com Cc: Jike Song , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Date: Sun, 19 Mar 2017 20:36:59 -0600 Message-ID: <20170320023646.18492.5455.stgit@gimli.home> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 20 Mar 2017 02:37:03 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The intent of the original warning is make sure that the mdev vendor driver has removed any group notifiers at the point where the group is closed by the user. Theoretically this would be through an orderly shutdown where any devices are release prior to the group release. We can't always count on an orderly shutdown, the user can close the group before the notifier can be removed or the user task might be killed. We'd like to add this sanity test when the group is idle and the only references are from the devices within the group themselves, but we don't have a good way to do that. Instead check both when the group itself is removed and when the group is opened. A bit later than we'd prefer, but better than the current over aggressive approach. Signed-off-by: Alex Williamson Cc: Jike Song --- drivers/vfio/vfio.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 609f4f982c74..561084ab387f 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -403,6 +403,7 @@ static void vfio_group_release(struct kref *kref) struct iommu_group *iommu_group = group->iommu_group; WARN_ON(!list_empty(&group->device_list)); + WARN_ON(group->notifier.head); list_for_each_entry_safe(unbound, tmp, &group->unbound_list, unbound_next) { @@ -1573,6 +1574,10 @@ static int vfio_group_fops_open(struct inode *inode, struct file *filep) return -EBUSY; } + /* Warn if previous user didn't cleanup and re-init to drop them */ + if (WARN_ON(group->notifier.head)) + BLOCKING_INIT_NOTIFIER_HEAD(&group->notifier); + filep->private_data = group; return 0; @@ -1584,9 +1589,6 @@ static int vfio_group_fops_release(struct inode *inode, struct file *filep) filep->private_data = NULL; - /* Any user didn't unregister? */ - WARN_ON(group->notifier.head); - vfio_group_try_dissolve_container(group); atomic_dec(&group->opened);