1 files changed, 65 insertions, 76 deletions

diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
index 3cc1a05fde1c..ed8608763134 100644
--- a/drivers/vfio/mdev/mdev_core.c
+++ b/drivers/vfio/mdev/mdev_core.c
@@ -1,13 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Mediated device Core Driver
  *
  * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
  *     Author: Neo Jia <cjia@nvidia.com>
  *             Kirti Wankhede <kwankhede@nvidia.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/module.h>
@@ -102,56 +99,35 @@ static void mdev_put_parent(struct mdev_parent *parent)
 		kref_put(&parent->ref, mdev_release_parent);
 }
 
-static int mdev_device_create_ops(struct kobject *kobj,
-				  struct mdev_device *mdev)
-{
-	struct mdev_parent *parent = mdev->parent;
-	int ret;
-
-	ret = parent->ops->create(kobj, mdev);
-	if (ret)
-		return ret;
-
-	ret = sysfs_create_groups(&mdev->dev.kobj,
-				  parent->ops->mdev_attr_groups);
-	if (ret)
-		parent->ops->remove(mdev);
-
-	return ret;
-}
-
-/*
- * 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.
- */
-static int mdev_device_remove_ops(struct mdev_device *mdev, bool force_remove)
+/* Caller must hold parent unreg_sem read or write lock */
+static void mdev_device_remove_common(struct mdev_device *mdev)
 {
-	struct mdev_parent *parent = mdev->parent;
+	struct mdev_parent *parent;
+	struct mdev_type *type;
 	int ret;
 
-	/*
-	 * Vendor driver can return error if VMM or userspace application is
-	 * using this mdev device.
-	 */
+	type = to_mdev_type(mdev->type_kobj);
+	mdev_remove_sysfs_files(&mdev->dev, type);
+	device_del(&mdev->dev);
+	parent = mdev->parent;
+	lockdep_assert_held(&parent->unreg_sem);
 	ret = parent->ops->remove(mdev);
-	if (ret && !force_remove)
-		return ret;
+	if (ret)
+		dev_err(&mdev->dev, "Remove failed: err=%d\n", ret);
 
-	sysfs_remove_groups(&mdev->dev.kobj, parent->ops->mdev_attr_groups);
-	return 0;
+	/* Balances with device_initialize() */
+	put_device(&mdev->dev);
+	mdev_put_parent(parent);
 }
 
 static int mdev_device_remove_cb(struct device *dev, void *data)
 {
-	if (dev_is_mdev(dev))
-		mdev_device_remove(dev, true);
+	if (dev_is_mdev(dev)) {
+		struct mdev_device *mdev;
 
+		mdev = to_mdev_device(dev);
+		mdev_device_remove_common(mdev);
+	}
 	return 0;
 }
 
@@ -193,6 +169,7 @@ int mdev_register_device(struct device *dev, const struct mdev_parent_ops *ops)
 	}
 
 	kref_init(&parent->ref);
+	init_rwsem(&parent->unreg_sem);
 
 	parent->dev = dev;
 	parent->ops = ops;
@@ -251,21 +228,23 @@ void mdev_unregister_device(struct device *dev)
 	dev_info(dev, "MDEV: Unregistering\n");
 
 	list_del(&parent->next);
+	mutex_unlock(&parent_list_lock);
+
+	down_write(&parent->unreg_sem);
+
 	class_compat_remove_link(mdev_bus_compat_class, dev, NULL);
 
 	device_for_each_child(dev, NULL, mdev_device_remove_cb);
 
 	parent_remove_sysfs_files(parent);
+	up_write(&parent->unreg_sem);
 
-	mutex_unlock(&parent_list_lock);
 	mdev_put_parent(parent);
 }
 EXPORT_SYMBOL(mdev_unregister_device);
 
-static void mdev_device_release(struct device *dev)
+static void mdev_device_free(struct mdev_device *mdev)
 {
-	struct mdev_device *mdev = to_mdev_device(dev);
-
 	mutex_lock(&mdev_list_lock);
 	list_del(&mdev->next);
 	mutex_unlock(&mdev_list_lock);
@@ -274,6 +253,13 @@ static void mdev_device_release(struct device *dev)
 	kfree(mdev);
 }
 
+static void mdev_device_release(struct device *dev)
+{
+	struct mdev_device *mdev = to_mdev_device(dev);
+
+	mdev_device_free(mdev);
+}
+
 int mdev_device_create(struct kobject *kobj,
 		       struct device *dev, const guid_t *uuid)
 {
@@ -310,46 +296,55 @@ int mdev_device_create(struct kobject *kobj,
 
 	mdev->parent = parent;
 
+	/* Check if parent unregistration has started */
+	if (!down_read_trylock(&parent->unreg_sem)) {
+		mdev_device_free(mdev);
+		ret = -ENODEV;
+		goto mdev_fail;
+	}
+
+	device_initialize(&mdev->dev);
 	mdev->dev.parent  = dev;
 	mdev->dev.bus     = &mdev_bus_type;
 	mdev->dev.release = mdev_device_release;
 	dev_set_name(&mdev->dev, "%pUl", uuid);
+	mdev->dev.groups = parent->ops->mdev_attr_groups;
+	mdev->type_kobj = kobj;
 
-	ret = device_register(&mdev->dev);
-	if (ret) {
-		put_device(&mdev->dev);
-		goto mdev_fail;
-	}
+	ret = parent->ops->create(kobj, mdev);
+	if (ret)
+		goto ops_create_fail;
 
-	ret = mdev_device_create_ops(kobj, mdev);
+	ret = device_add(&mdev->dev);
 	if (ret)
-		goto create_fail;
+		goto add_fail;
 
 	ret = mdev_create_sysfs_files(&mdev->dev, type);
-	if (ret) {
-		mdev_device_remove_ops(mdev, true);
-		goto create_fail;
-	}
+	if (ret)
+		goto sysfs_fail;
 
-	mdev->type_kobj = kobj;
 	mdev->active = true;
 	dev_dbg(&mdev->dev, "MDEV: created\n");
+	up_read(&parent->unreg_sem);
 
 	return 0;
 
-create_fail:
-	device_unregister(&mdev->dev);
+sysfs_fail:
+	device_del(&mdev->dev);
+add_fail:
+	parent->ops->remove(mdev);
+ops_create_fail:
+	up_read(&parent->unreg_sem);
+	put_device(&mdev->dev);
 mdev_fail:
 	mdev_put_parent(parent);
 	return ret;
 }
 
-int mdev_device_remove(struct device *dev, bool force_remove)
+int mdev_device_remove(struct device *dev)
 {
 	struct mdev_device *mdev, *tmp;
 	struct mdev_parent *parent;
-	struct mdev_type *type;
-	int ret;
 
 	mdev = to_mdev_device(dev);
 
@@ -372,19 +367,13 @@ int mdev_device_remove(struct device *dev, bool force_remove)
 	mdev->active = false;
 	mutex_unlock(&mdev_list_lock);
 
-	type = to_mdev_type(mdev->type_kobj);
 	parent = mdev->parent;
+	/* Check if parent unregistration has started */
+	if (!down_read_trylock(&parent->unreg_sem))
+		return -ENODEV;
 
-	ret = mdev_device_remove_ops(mdev, force_remove);
-	if (ret) {
-		mdev->active = true;
-		return ret;
-	}
-
-	mdev_remove_sysfs_files(dev, type);
-	device_unregister(dev);
-	mdev_put_parent(parent);
-
+	mdev_device_remove_common(mdev);
+	up_read(&parent->unreg_sem);
 	return 0;
 }