ff598081e5
The pointer to mdev_bus_compat_class is statically defined at the top of mdev_core, and was originally (commit7b96953bc6
("vfio: Mediated device Core driver") serialized by the parent_list_lock. The blamed commit removed this mutex, leaving the pointer initialization unserialized. As a result, the creation of multiple MDEVs in parallel (such as during boot) can encounter errors during the creation of the sysfs entries, such as: [ 8.337509] sysfs: cannot create duplicate filename '/class/mdev_bus' [ 8.337514] vfio_ccw 0.0.01d8: MDEV: Registered [ 8.337516] CPU: 13 PID: 946 Comm: driverctl Not tainted 6.4.0-rc7 #20 [ 8.337522] Hardware name: IBM 3906 M05 780 (LPAR) [ 8.337525] Call Trace: [ 8.337528] [<0000000162b0145a>] dump_stack_lvl+0x62/0x80 [ 8.337540] [<00000001622aeb30>] sysfs_warn_dup+0x78/0x88 [ 8.337549] [<00000001622aeca6>] sysfs_create_dir_ns+0xe6/0xf8 [ 8.337552] [<0000000162b04504>] kobject_add_internal+0xf4/0x340 [ 8.337557] [<0000000162b04d48>] kobject_add+0x78/0xd0 [ 8.337561] [<0000000162b04e0a>] kobject_create_and_add+0x6a/0xb8 [ 8.337565] [<00000001627a110e>] class_compat_register+0x5e/0x90 [ 8.337572] [<000003ff7fd815da>] mdev_register_parent+0x102/0x130 [mdev] [ 8.337581] [<000003ff7fdc7f2c>] vfio_ccw_sch_probe+0xe4/0x178 [vfio_ccw] [ 8.337588] [<0000000162a7833c>] css_probe+0x44/0x80 [ 8.337599] [<000000016279f4da>] really_probe+0xd2/0x460 [ 8.337603] [<000000016279fa08>] driver_probe_device+0x40/0xf0 [ 8.337606] [<000000016279fb78>] __device_attach_driver+0xc0/0x140 [ 8.337610] [<000000016279cbe0>] bus_for_each_drv+0x90/0xd8 [ 8.337618] [<00000001627a00b0>] __device_attach+0x110/0x190 [ 8.337621] [<000000016279c7c8>] bus_rescan_devices_helper+0x60/0xb0 [ 8.337626] [<000000016279cd48>] drivers_probe_store+0x48/0x80 [ 8.337632] [<00000001622ac9b0>] kernfs_fop_write_iter+0x138/0x1f0 [ 8.337635] [<00000001621e5e14>] vfs_write+0x1ac/0x2f8 [ 8.337645] [<00000001621e61d8>] ksys_write+0x70/0x100 [ 8.337650] [<0000000162b2bdc4>] __do_syscall+0x1d4/0x200 [ 8.337656] [<0000000162b3c828>] system_call+0x70/0x98 [ 8.337664] kobject: kobject_add_internal failed for mdev_bus with -EEXIST, don't try to register things with the same name in the same directory. [ 8.337668] kobject: kobject_create_and_add: kobject_add error: -17 [ 8.337674] vfio_ccw: probe of 0.0.01d9 failed with error -12 [ 8.342941] vfio_ccw_mdev aeb9ca91-10c6-42bc-a168-320023570aea: Adding to iommu group 2 Move the initialization of the mdev_bus_compat_class pointer to the init path, to match the cleanup in module exit. This way the code in mdev_register_parent() can simply link the new parent to it, rather than determining whether initialization is required first. Fixes:89345d5177
("vfio/mdev: embedd struct mdev_parent in the parent data structure") Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com> Signed-off-by: Eric Farman <farman@linux.ibm.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/20230626133642.2939168-1-farman@linux.ibm.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
276 lines
6.6 KiB
C
276 lines
6.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Mediated device Core Driver
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*
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* Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
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* Author: Neo Jia <cjia@nvidia.com>
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* Kirti Wankhede <kwankhede@nvidia.com>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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#include <linux/mdev.h>
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#include "mdev_private.h"
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#define DRIVER_VERSION "0.1"
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#define DRIVER_AUTHOR "NVIDIA Corporation"
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#define DRIVER_DESC "Mediated device Core Driver"
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static struct class_compat *mdev_bus_compat_class;
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static LIST_HEAD(mdev_list);
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static DEFINE_MUTEX(mdev_list_lock);
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/* Caller must hold parent unreg_sem read or write lock */
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static void mdev_device_remove_common(struct mdev_device *mdev)
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{
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struct mdev_parent *parent = mdev->type->parent;
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mdev_remove_sysfs_files(mdev);
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device_del(&mdev->dev);
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lockdep_assert_held(&parent->unreg_sem);
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/* Balances with device_initialize() */
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put_device(&mdev->dev);
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}
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static int mdev_device_remove_cb(struct device *dev, void *data)
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{
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if (dev->bus == &mdev_bus_type)
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mdev_device_remove_common(to_mdev_device(dev));
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return 0;
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}
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/*
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* mdev_register_parent: Register a device as parent for mdevs
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* @parent: parent structure registered
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* @dev: device structure representing parent device.
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* @mdev_driver: Device driver to bind to the newly created mdev
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* @types: Array of supported mdev types
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* @nr_types: Number of entries in @types
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*
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* Registers the @parent stucture as a parent for mdev types and thus mdev
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* devices. The caller needs to hold a reference on @dev that must not be
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* released until after the call to mdev_unregister_parent().
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*
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* Returns a negative value on error, otherwise 0.
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*/
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int mdev_register_parent(struct mdev_parent *parent, struct device *dev,
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struct mdev_driver *mdev_driver, struct mdev_type **types,
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unsigned int nr_types)
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{
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char *env_string = "MDEV_STATE=registered";
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char *envp[] = { env_string, NULL };
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int ret;
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memset(parent, 0, sizeof(*parent));
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init_rwsem(&parent->unreg_sem);
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parent->dev = dev;
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parent->mdev_driver = mdev_driver;
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parent->types = types;
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parent->nr_types = nr_types;
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atomic_set(&parent->available_instances, mdev_driver->max_instances);
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ret = parent_create_sysfs_files(parent);
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if (ret)
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return ret;
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ret = class_compat_create_link(mdev_bus_compat_class, dev, NULL);
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if (ret)
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dev_warn(dev, "Failed to create compatibility class link\n");
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dev_info(dev, "MDEV: Registered\n");
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kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, envp);
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return 0;
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}
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EXPORT_SYMBOL(mdev_register_parent);
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/*
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* mdev_unregister_parent : Unregister a parent device
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* @parent: parent structure to unregister
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*/
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void mdev_unregister_parent(struct mdev_parent *parent)
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{
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char *env_string = "MDEV_STATE=unregistered";
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char *envp[] = { env_string, NULL };
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dev_info(parent->dev, "MDEV: Unregistering\n");
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down_write(&parent->unreg_sem);
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class_compat_remove_link(mdev_bus_compat_class, parent->dev, NULL);
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device_for_each_child(parent->dev, NULL, mdev_device_remove_cb);
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parent_remove_sysfs_files(parent);
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up_write(&parent->unreg_sem);
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kobject_uevent_env(&parent->dev->kobj, KOBJ_CHANGE, envp);
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}
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EXPORT_SYMBOL(mdev_unregister_parent);
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static void mdev_device_release(struct device *dev)
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{
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struct mdev_device *mdev = to_mdev_device(dev);
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struct mdev_parent *parent = mdev->type->parent;
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mutex_lock(&mdev_list_lock);
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list_del(&mdev->next);
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if (!parent->mdev_driver->get_available)
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atomic_inc(&parent->available_instances);
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mutex_unlock(&mdev_list_lock);
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/* Pairs with the get in mdev_device_create() */
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kobject_put(&mdev->type->kobj);
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dev_dbg(&mdev->dev, "MDEV: destroying\n");
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kfree(mdev);
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}
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int mdev_device_create(struct mdev_type *type, const guid_t *uuid)
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{
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int ret;
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struct mdev_device *mdev, *tmp;
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struct mdev_parent *parent = type->parent;
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struct mdev_driver *drv = parent->mdev_driver;
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mutex_lock(&mdev_list_lock);
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/* Check for duplicate */
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list_for_each_entry(tmp, &mdev_list, next) {
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if (guid_equal(&tmp->uuid, uuid)) {
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mutex_unlock(&mdev_list_lock);
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return -EEXIST;
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}
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}
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if (!drv->get_available) {
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/*
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* Note: that non-atomic read and dec is fine here because
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* all modifications are under mdev_list_lock.
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*/
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if (!atomic_read(&parent->available_instances)) {
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mutex_unlock(&mdev_list_lock);
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return -EUSERS;
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}
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atomic_dec(&parent->available_instances);
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}
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mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
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if (!mdev) {
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mutex_unlock(&mdev_list_lock);
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return -ENOMEM;
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}
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device_initialize(&mdev->dev);
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mdev->dev.parent = parent->dev;
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mdev->dev.bus = &mdev_bus_type;
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mdev->dev.release = mdev_device_release;
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mdev->dev.groups = mdev_device_groups;
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mdev->type = type;
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/* Pairs with the put in mdev_device_release() */
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kobject_get(&type->kobj);
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guid_copy(&mdev->uuid, uuid);
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list_add(&mdev->next, &mdev_list);
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mutex_unlock(&mdev_list_lock);
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ret = dev_set_name(&mdev->dev, "%pUl", uuid);
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if (ret)
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goto out_put_device;
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/* Check if parent unregistration has started */
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if (!down_read_trylock(&parent->unreg_sem)) {
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ret = -ENODEV;
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goto out_put_device;
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}
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ret = device_add(&mdev->dev);
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if (ret)
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goto out_unlock;
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ret = device_driver_attach(&drv->driver, &mdev->dev);
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if (ret)
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goto out_del;
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ret = mdev_create_sysfs_files(mdev);
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if (ret)
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goto out_del;
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mdev->active = true;
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dev_dbg(&mdev->dev, "MDEV: created\n");
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up_read(&parent->unreg_sem);
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return 0;
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out_del:
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device_del(&mdev->dev);
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out_unlock:
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up_read(&parent->unreg_sem);
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out_put_device:
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put_device(&mdev->dev);
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return ret;
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}
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int mdev_device_remove(struct mdev_device *mdev)
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{
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struct mdev_device *tmp;
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struct mdev_parent *parent = mdev->type->parent;
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mutex_lock(&mdev_list_lock);
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list_for_each_entry(tmp, &mdev_list, next) {
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if (tmp == mdev)
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break;
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}
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if (tmp != mdev) {
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mutex_unlock(&mdev_list_lock);
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return -ENODEV;
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}
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if (!mdev->active) {
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mutex_unlock(&mdev_list_lock);
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return -EAGAIN;
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}
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mdev->active = false;
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mutex_unlock(&mdev_list_lock);
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/* Check if parent unregistration has started */
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if (!down_read_trylock(&parent->unreg_sem))
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return -ENODEV;
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mdev_device_remove_common(mdev);
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up_read(&parent->unreg_sem);
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return 0;
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}
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static int __init mdev_init(void)
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{
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int ret;
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ret = bus_register(&mdev_bus_type);
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if (ret)
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return ret;
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mdev_bus_compat_class = class_compat_register("mdev_bus");
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if (!mdev_bus_compat_class) {
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bus_unregister(&mdev_bus_type);
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return -ENOMEM;
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}
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return 0;
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}
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static void __exit mdev_exit(void)
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{
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class_compat_unregister(mdev_bus_compat_class);
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bus_unregister(&mdev_bus_type);
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}
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subsys_initcall(mdev_init)
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module_exit(mdev_exit)
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MODULE_VERSION(DRIVER_VERSION);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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