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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 D6EE0C43381 for ; Mon, 25 Mar 2019 19:35:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A437520854 for ; Mon, 25 Mar 2019 19:35:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="MO7pEY6q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730236AbfCYTfl (ORCPT ); Mon, 25 Mar 2019 15:35:41 -0400 Received: from hqemgate14.nvidia.com ([216.228.121.143]:17713 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729632AbfCYTfl (ORCPT ); Mon, 25 Mar 2019 15:35:41 -0400 Received: from hqpgpgate102.nvidia.com (Not Verified[216.228.121.13]) by hqemgate14.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 25 Mar 2019 12:35:43 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate102.nvidia.com (PGP Universal service); Mon, 25 Mar 2019 12:35:40 -0700 X-PGP-Universal: processed; by hqpgpgate102.nvidia.com on Mon, 25 Mar 2019 12:35:40 -0700 Received: from [10.24.70.95] (10.124.1.5) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 25 Mar 2019 19:35:37 +0000 Subject: Re: [PATCH 7/8] vfio/mdev: Fix aborting mdev child device removal if one fails To: Parav Pandit , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "alex.williamson@redhat.com" References: <1553296835-37522-1-git-send-email-parav@mellanox.com> <1553296835-37522-8-git-send-email-parav@mellanox.com> X-Nvconfidentiality: public From: Kirti Wankhede Message-ID: Date: Tue, 26 Mar 2019 01:05:34 +0530 MIME-Version: 1.0 In-Reply-To: <1553296835-37522-8-git-send-email-parav@mellanox.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1553542543; bh=Af8qLPfmOgXrjW++mAogPWXGaygjK/yWaXqDty1r2u0=; h=X-PGP-Universal:Subject:To:References:X-Nvconfidentiality:From: Message-ID:Date:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=MO7pEY6qjht/ldei/W7eAVuMRnHdVkUmYAaKgWcLuIMOzZWWHVBk7BFiWylofrqQ7 NvaZgUAcaCNtO/K9n5sduG3NwswngCQpcPPwAw1QQGCl8apsLmSxeQQHdDY1rbr+do 6x4//vjx/SI6EKRpq+0ivbt6iz8uxB2uNv3C4dPECQg2pNezSAaxCxoxlFbX9s+6Ur 29kPuufSA86YnFeXrgDeQUtYOg5jgaFtmFoYe+1duQ+UyVLqP1gVXz5TJY7E1j5iO2 0w7mWEjS5XnJ/0eMZzWgKi7ubKgNiIv3NqW6G+m3Ydna2XJKNY0mKHDOjNitBO0459 jjuMbasfOYhVg== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/23/2019 4:50 AM, Parav Pandit wrote: > device_for_each_child() stops executing callback function for remaining > child devices, if callback hits an error. > Each child mdev device is independent of each other. > While unregistering parent device, mdev core must remove all child mdev > devices. > Therefore, mdev_device_remove_cb() always returns success so that > device_for_each_child doesn't abort if one child removal hits error. > When unregistering parent device, force_remove is set to true amd mdev_device_remove_ops() always returns success. > While at it, improve remove and unregister functions for below simplicity. > > There isn't need to pass forced flag pointer during mdev parent > removal which invokes mdev_device_remove(). There is a need to pass the flag, pasting here the comment above mdev_device_remove_ops() which explains why the flag is needed: /* * mdev_device_remove_ops gets called from sysfs's 'remove' and when parent * device is being unregistered from mdev device framework. * - 'force_remove' is set to 'false' when called from sysfs's 'remove' which * indicates that if the mdev device is active, used by VMM or userspace * application, vendor driver could return error then don't remove the device. * - 'force_remove' is set to 'true' when called from mdev_unregister_device() * which indicate that parent device is being removed from mdev device * framework so remove mdev device forcefully. */ Thanks, Kirti So simplify the flow. > > mdev_device_remove() is called from two paths. > 1. mdev_unregister_driver() > mdev_device_remove_cb() > mdev_device_remove() > 2. remove_store() > mdev_device_remove() > > When device is removed by user using remote_store(), device under > removal is mdev device. > When device is removed during parent device removal using generic child > iterator, mdev check is already done using dev_is_mdev(). > > Hence, remove the unnecessary loop in mdev_device_remove(). > > Fixes: 7b96953bc640 ("vfio: Mediated device Core driver") > Signed-off-by: Parav Pandit > --- > drivers/vfio/mdev/mdev_core.c | 24 +++++------------------- > 1 file changed, 5 insertions(+), 19 deletions(-) > > diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c > index ab05464..944a058 100644 > --- a/drivers/vfio/mdev/mdev_core.c > +++ b/drivers/vfio/mdev/mdev_core.c > @@ -150,10 +150,10 @@ static int mdev_device_remove_ops(struct mdev_device *mdev, bool force_remove) > > static int mdev_device_remove_cb(struct device *dev, void *data) > { > - if (!dev_is_mdev(dev)) > - return 0; > + if (dev_is_mdev(dev)) > + mdev_device_remove(dev, true); > > - return mdev_device_remove(dev, data ? *(bool *)data : true); > + return 0; > } > > /* > @@ -241,7 +241,6 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops) > void mdev_unregister_device(struct device *dev) > { > struct mdev_parent *parent; > - bool force_remove = true; > > mutex_lock(&parent_list_lock); > parent = __find_parent_device(dev); > @@ -255,8 +254,7 @@ void mdev_unregister_device(struct device *dev) > list_del(&parent->next); > class_compat_remove_link(mdev_bus_compat_class, dev, NULL); > > - device_for_each_child(dev, (void *)&force_remove, > - mdev_device_remove_cb); > + device_for_each_child(dev, NULL, mdev_device_remove_cb); > > parent_remove_sysfs_files(parent); > > @@ -346,24 +344,12 @@ int mdev_device_create(struct kobject *kobj, struct device *dev, uuid_le uuid) > > int mdev_device_remove(struct device *dev, bool force_remove) > { > - struct mdev_device *mdev, *tmp; > + struct mdev_device *mdev; > struct mdev_parent *parent; > struct mdev_type *type; > int ret; > > mdev = to_mdev_device(dev); > - > - mutex_lock(&mdev_list_lock); > - list_for_each_entry(tmp, &mdev_list, next) { > - if (tmp == mdev) > - break; > - } > - > - if (tmp != mdev) { > - mutex_unlock(&mdev_list_lock); > - return -ENODEV; > - } > - > if (!mdev->active) { > mutex_unlock(&mdev_list_lock); > return -EAGAIN; >