2 * drivers/base/dd.c - The core device/driver interactions.
4 * This file contains the (sometimes tricky) code that controls the
5 * interactions between devices and drivers, which primarily includes
6 * driver binding and unbinding.
8 * All of this code used to exist in drivers/base/bus.c, but was
9 * relocated to here in the name of compartmentalization (since it wasn't
10 * strictly code just for the 'struct bus_type'.
12 * Copyright (c) 2002-5 Patrick Mochel
13 * Copyright (c) 2002-3 Open Source Development Labs
14 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
15 * Copyright (c) 2007-2009 Novell Inc.
17 * This file is released under the GPLv2
20 #include <linux/device.h>
21 #include <linux/delay.h>
22 #include <linux/dma-mapping.h>
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/kthread.h>
26 #include <linux/wait.h>
27 #include <linux/async.h>
28 #include <linux/pm_runtime.h>
29 #include <linux/pinctrl/devinfo.h>
32 #include "power/power.h"
35 * Deferred Probe infrastructure.
37 * Sometimes driver probe order matters, but the kernel doesn't always have
38 * dependency information which means some drivers will get probed before a
39 * resource it depends on is available. For example, an SDHCI driver may
40 * first need a GPIO line from an i2c GPIO controller before it can be
41 * initialized. If a required resource is not available yet, a driver can
42 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
44 * Deferred probe maintains two lists of devices, a pending list and an active
45 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
46 * pending list. A successful driver probe will trigger moving all devices
47 * from the pending to the active list so that the workqueue will eventually
50 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
51 * of the (struct device*)->p->deferred_probe pointers are manipulated
53 static DEFINE_MUTEX(deferred_probe_mutex
);
54 static LIST_HEAD(deferred_probe_pending_list
);
55 static LIST_HEAD(deferred_probe_active_list
);
56 static atomic_t deferred_trigger_count
= ATOMIC_INIT(0);
57 static bool initcalls_done
;
60 * In some cases, like suspend to RAM or hibernation, It might be reasonable
61 * to prohibit probing of devices as it could be unsafe.
62 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
64 static bool defer_all_probes
;
67 * For initcall_debug, show the deferred probes executed in late_initcall
70 static void deferred_probe_debug(struct device
*dev
)
72 ktime_t calltime
, delta
, rettime
;
73 unsigned long long duration
;
75 printk(KERN_DEBUG
"deferred probe %s @ %i\n", dev_name(dev
),
76 task_pid_nr(current
));
77 calltime
= ktime_get();
78 bus_probe_device(dev
);
79 rettime
= ktime_get();
80 delta
= ktime_sub(rettime
, calltime
);
81 duration
= (unsigned long long) ktime_to_ns(delta
) >> 10;
82 printk(KERN_DEBUG
"deferred probe %s returned after %lld usecs\n",
83 dev_name(dev
), duration
);
87 * deferred_probe_work_func() - Retry probing devices in the active list.
89 static void deferred_probe_work_func(struct work_struct
*work
)
92 struct device_private
*private;
94 * This block processes every device in the deferred 'active' list.
95 * Each device is removed from the active list and passed to
96 * bus_probe_device() to re-attempt the probe. The loop continues
97 * until every device in the active list is removed and retried.
99 * Note: Once the device is removed from the list and the mutex is
100 * released, it is possible for the device get freed by another thread
101 * and cause a illegal pointer dereference. This code uses
102 * get/put_device() to ensure the device structure cannot disappear
103 * from under our feet.
105 mutex_lock(&deferred_probe_mutex
);
106 while (!list_empty(&deferred_probe_active_list
)) {
107 private = list_first_entry(&deferred_probe_active_list
,
108 typeof(*dev
->p
), deferred_probe
);
109 dev
= private->device
;
110 list_del_init(&private->deferred_probe
);
115 * Drop the mutex while probing each device; the probe path may
116 * manipulate the deferred list
118 mutex_unlock(&deferred_probe_mutex
);
121 * Force the device to the end of the dpm_list since
122 * the PM code assumes that the order we add things to
123 * the list is a good order for suspend but deferred
124 * probe makes that very unsafe.
127 device_pm_move_last(dev
);
130 dev_dbg(dev
, "Retrying from deferred list\n");
131 if (initcall_debug
&& !initcalls_done
)
132 deferred_probe_debug(dev
);
134 bus_probe_device(dev
);
136 mutex_lock(&deferred_probe_mutex
);
140 mutex_unlock(&deferred_probe_mutex
);
142 static DECLARE_WORK(deferred_probe_work
, deferred_probe_work_func
);
144 static void driver_deferred_probe_add(struct device
*dev
)
146 mutex_lock(&deferred_probe_mutex
);
147 if (list_empty(&dev
->p
->deferred_probe
)) {
148 dev_dbg(dev
, "Added to deferred list\n");
149 list_add_tail(&dev
->p
->deferred_probe
, &deferred_probe_pending_list
);
151 mutex_unlock(&deferred_probe_mutex
);
154 void driver_deferred_probe_del(struct device
*dev
)
156 mutex_lock(&deferred_probe_mutex
);
157 if (!list_empty(&dev
->p
->deferred_probe
)) {
158 dev_dbg(dev
, "Removed from deferred list\n");
159 list_del_init(&dev
->p
->deferred_probe
);
161 mutex_unlock(&deferred_probe_mutex
);
164 static bool driver_deferred_probe_enable
= false;
166 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
168 * This functions moves all devices from the pending list to the active
169 * list and schedules the deferred probe workqueue to process them. It
170 * should be called anytime a driver is successfully bound to a device.
172 * Note, there is a race condition in multi-threaded probe. In the case where
173 * more than one device is probing at the same time, it is possible for one
174 * probe to complete successfully while another is about to defer. If the second
175 * depends on the first, then it will get put on the pending list after the
176 * trigger event has already occurred and will be stuck there.
178 * The atomic 'deferred_trigger_count' is used to determine if a successful
179 * trigger has occurred in the midst of probing a driver. If the trigger count
180 * changes in the midst of a probe, then deferred processing should be triggered
183 static void driver_deferred_probe_trigger(void)
185 if (!driver_deferred_probe_enable
)
189 * A successful probe means that all the devices in the pending list
190 * should be triggered to be reprobed. Move all the deferred devices
191 * into the active list so they can be retried by the workqueue
193 mutex_lock(&deferred_probe_mutex
);
194 atomic_inc(&deferred_trigger_count
);
195 list_splice_tail_init(&deferred_probe_pending_list
,
196 &deferred_probe_active_list
);
197 mutex_unlock(&deferred_probe_mutex
);
200 * Kick the re-probe thread. It may already be scheduled, but it is
201 * safe to kick it again.
203 schedule_work(&deferred_probe_work
);
207 * device_block_probing() - Block/defere device's probes
209 * It will disable probing of devices and defer their probes instead.
211 void device_block_probing(void)
213 defer_all_probes
= true;
214 /* sync with probes to avoid races. */
215 wait_for_device_probe();
219 * device_unblock_probing() - Unblock/enable device's probes
221 * It will restore normal behavior and trigger re-probing of deferred
224 void device_unblock_probing(void)
226 defer_all_probes
= false;
227 driver_deferred_probe_trigger();
231 * deferred_probe_initcall() - Enable probing of deferred devices
233 * We don't want to get in the way when the bulk of drivers are getting probed.
234 * Instead, this initcall makes sure that deferred probing is delayed until
235 * late_initcall time.
237 static int deferred_probe_initcall(void)
239 driver_deferred_probe_enable
= true;
240 driver_deferred_probe_trigger();
241 /* Sort as many dependencies as possible before exiting initcalls */
242 flush_work(&deferred_probe_work
);
243 initcalls_done
= true;
246 late_initcall(deferred_probe_initcall
);
249 * device_is_bound() - Check if device is bound to a driver
250 * @dev: device to check
252 * Returns true if passed device has already finished probing successfully
255 * This function must be called with the device lock held.
257 bool device_is_bound(struct device
*dev
)
259 return dev
->p
&& klist_node_attached(&dev
->p
->knode_driver
);
262 static void driver_bound(struct device
*dev
)
264 if (device_is_bound(dev
)) {
265 printk(KERN_WARNING
"%s: device %s already bound\n",
266 __func__
, kobject_name(&dev
->kobj
));
270 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev
->driver
->name
,
271 __func__
, dev_name(dev
));
273 klist_add_tail(&dev
->p
->knode_driver
, &dev
->driver
->p
->klist_devices
);
274 device_links_driver_bound(dev
);
276 device_pm_check_callbacks(dev
);
279 * Make sure the device is no longer in one of the deferred lists and
280 * kick off retrying all pending devices
282 driver_deferred_probe_del(dev
);
283 driver_deferred_probe_trigger();
286 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
287 BUS_NOTIFY_BOUND_DRIVER
, dev
);
289 kobject_uevent(&dev
->kobj
, KOBJ_BIND
);
292 static int driver_sysfs_add(struct device
*dev
)
297 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
298 BUS_NOTIFY_BIND_DRIVER
, dev
);
300 ret
= sysfs_create_link(&dev
->driver
->p
->kobj
, &dev
->kobj
,
301 kobject_name(&dev
->kobj
));
303 ret
= sysfs_create_link(&dev
->kobj
, &dev
->driver
->p
->kobj
,
306 sysfs_remove_link(&dev
->driver
->p
->kobj
,
307 kobject_name(&dev
->kobj
));
312 static void driver_sysfs_remove(struct device
*dev
)
314 struct device_driver
*drv
= dev
->driver
;
317 sysfs_remove_link(&drv
->p
->kobj
, kobject_name(&dev
->kobj
));
318 sysfs_remove_link(&dev
->kobj
, "driver");
323 * device_bind_driver - bind a driver to one device.
326 * Allow manual attachment of a driver to a device.
327 * Caller must have already set @dev->driver.
329 * Note that this does not modify the bus reference count
330 * nor take the bus's rwsem. Please verify those are accounted
331 * for before calling this. (It is ok to call with no other effort
332 * from a driver's probe() method.)
334 * This function must be called with the device lock held.
336 int device_bind_driver(struct device
*dev
)
340 ret
= driver_sysfs_add(dev
);
344 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
345 BUS_NOTIFY_DRIVER_NOT_BOUND
, dev
);
348 EXPORT_SYMBOL_GPL(device_bind_driver
);
350 static atomic_t probe_count
= ATOMIC_INIT(0);
351 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue
);
353 static int really_probe(struct device
*dev
, struct device_driver
*drv
)
355 int ret
= -EPROBE_DEFER
;
356 int local_trigger_count
= atomic_read(&deferred_trigger_count
);
357 bool test_remove
= IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE
) &&
358 !drv
->suppress_bind_attrs
;
360 if (defer_all_probes
) {
362 * Value of defer_all_probes can be set only by
363 * device_defer_all_probes_enable() which, in turn, will call
364 * wait_for_device_probe() right after that to avoid any races.
366 dev_dbg(dev
, "Driver %s force probe deferral\n", drv
->name
);
367 driver_deferred_probe_add(dev
);
371 ret
= device_links_check_suppliers(dev
);
375 atomic_inc(&probe_count
);
376 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
377 drv
->bus
->name
, __func__
, drv
->name
, dev_name(dev
));
378 WARN_ON(!list_empty(&dev
->devres_head
));
383 /* If using pinctrl, bind pins now before probing */
384 ret
= pinctrl_bind_pins(dev
);
386 goto pinctrl_bind_failed
;
388 ret
= dma_configure(dev
);
392 if (driver_sysfs_add(dev
)) {
393 printk(KERN_ERR
"%s: driver_sysfs_add(%s) failed\n",
394 __func__
, dev_name(dev
));
398 if (dev
->pm_domain
&& dev
->pm_domain
->activate
) {
399 ret
= dev
->pm_domain
->activate(dev
);
404 if (dev
->bus
->probe
) {
405 ret
= dev
->bus
->probe(dev
);
408 } else if (drv
->probe
) {
409 ret
= drv
->probe(dev
);
417 if (dev
->bus
->remove
)
418 dev
->bus
->remove(dev
);
419 else if (drv
->remove
)
422 devres_release_all(dev
);
423 driver_sysfs_remove(dev
);
425 dev_set_drvdata(dev
, NULL
);
426 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
427 dev
->pm_domain
->dismiss(dev
);
428 pm_runtime_reinit(dev
);
433 pinctrl_init_done(dev
);
435 if (dev
->pm_domain
&& dev
->pm_domain
->sync
)
436 dev
->pm_domain
->sync(dev
);
440 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
441 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
445 dma_deconfigure(dev
);
448 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
449 BUS_NOTIFY_DRIVER_NOT_BOUND
, dev
);
451 device_links_no_driver(dev
);
452 devres_release_all(dev
);
453 driver_sysfs_remove(dev
);
455 dev_set_drvdata(dev
, NULL
);
456 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
457 dev
->pm_domain
->dismiss(dev
);
458 pm_runtime_reinit(dev
);
462 /* Driver requested deferred probing */
463 dev_dbg(dev
, "Driver %s requests probe deferral\n", drv
->name
);
464 driver_deferred_probe_add(dev
);
465 /* Did a trigger occur while probing? Need to re-trigger if yes */
466 if (local_trigger_count
!= atomic_read(&deferred_trigger_count
))
467 driver_deferred_probe_trigger();
471 pr_debug("%s: probe of %s rejects match %d\n",
472 drv
->name
, dev_name(dev
), ret
);
475 /* driver matched but the probe failed */
477 "%s: probe of %s failed with error %d\n",
478 drv
->name
, dev_name(dev
), ret
);
481 * Ignore errors returned by ->probe so that the next driver can try
486 atomic_dec(&probe_count
);
487 wake_up(&probe_waitqueue
);
493 * Determine if the probe sequence is finished or not.
495 * Should somehow figure out how to use a semaphore, not an atomic variable...
497 int driver_probe_done(void)
499 pr_debug("%s: probe_count = %d\n", __func__
,
500 atomic_read(&probe_count
));
501 if (atomic_read(&probe_count
))
507 * wait_for_device_probe
508 * Wait for device probing to be completed.
510 void wait_for_device_probe(void)
512 /* wait for the deferred probe workqueue to finish */
513 flush_work(&deferred_probe_work
);
515 /* wait for the known devices to complete their probing */
516 wait_event(probe_waitqueue
, atomic_read(&probe_count
) == 0);
517 async_synchronize_full();
519 EXPORT_SYMBOL_GPL(wait_for_device_probe
);
522 * driver_probe_device - attempt to bind device & driver together
523 * @drv: driver to bind a device to
524 * @dev: device to try to bind to the driver
526 * This function returns -ENODEV if the device is not registered,
527 * 1 if the device is bound successfully and 0 otherwise.
529 * This function must be called with @dev lock held. When called for a
530 * USB interface, @dev->parent lock must be held as well.
532 * If the device has a parent, runtime-resume the parent before driver probing.
534 int driver_probe_device(struct device_driver
*drv
, struct device
*dev
)
538 if (!device_is_registered(dev
))
541 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
542 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
544 pm_runtime_get_suppliers(dev
);
546 pm_runtime_get_sync(dev
->parent
);
548 pm_runtime_barrier(dev
);
549 ret
= really_probe(dev
, drv
);
550 pm_request_idle(dev
);
553 pm_runtime_put(dev
->parent
);
555 pm_runtime_put_suppliers(dev
);
559 bool driver_allows_async_probing(struct device_driver
*drv
)
561 switch (drv
->probe_type
) {
562 case PROBE_PREFER_ASYNCHRONOUS
:
565 case PROBE_FORCE_SYNCHRONOUS
:
569 if (module_requested_async_probing(drv
->owner
))
576 struct device_attach_data
{
580 * Indicates whether we are are considering asynchronous probing or
581 * not. Only initial binding after device or driver registration
582 * (including deferral processing) may be done asynchronously, the
583 * rest is always synchronous, as we expect it is being done by
584 * request from userspace.
589 * Indicates if we are binding synchronous or asynchronous drivers.
590 * When asynchronous probing is enabled we'll execute 2 passes
591 * over drivers: first pass doing synchronous probing and second
592 * doing asynchronous probing (if synchronous did not succeed -
593 * most likely because there was no driver requiring synchronous
594 * probing - and we found asynchronous driver during first pass).
595 * The 2 passes are done because we can't shoot asynchronous
596 * probe for given device and driver from bus_for_each_drv() since
597 * driver pointer is not guaranteed to stay valid once
598 * bus_for_each_drv() iterates to the next driver on the bus.
603 * We'll set have_async to 'true' if, while scanning for matching
604 * driver, we'll encounter one that requests asynchronous probing.
609 static int __device_attach_driver(struct device_driver
*drv
, void *_data
)
611 struct device_attach_data
*data
= _data
;
612 struct device
*dev
= data
->dev
;
617 * Check if device has already been claimed. This may
618 * happen with driver loading, device discovery/registration,
619 * and deferred probe processing happens all at once with
625 ret
= driver_match_device(drv
, dev
);
629 } else if (ret
== -EPROBE_DEFER
) {
630 dev_dbg(dev
, "Device match requests probe deferral\n");
631 driver_deferred_probe_add(dev
);
632 } else if (ret
< 0) {
633 dev_dbg(dev
, "Bus failed to match device: %d", ret
);
635 } /* ret > 0 means positive match */
637 async_allowed
= driver_allows_async_probing(drv
);
640 data
->have_async
= true;
642 if (data
->check_async
&& async_allowed
!= data
->want_async
)
645 return driver_probe_device(drv
, dev
);
648 static void __device_attach_async_helper(void *_dev
, async_cookie_t cookie
)
650 struct device
*dev
= _dev
;
651 struct device_attach_data data
= {
660 pm_runtime_get_sync(dev
->parent
);
662 bus_for_each_drv(dev
->bus
, NULL
, &data
, __device_attach_driver
);
663 dev_dbg(dev
, "async probe completed\n");
665 pm_request_idle(dev
);
668 pm_runtime_put(dev
->parent
);
675 static int __device_attach(struct device
*dev
, bool allow_async
)
681 if (device_is_bound(dev
)) {
685 ret
= device_bind_driver(dev
);
693 struct device_attach_data data
= {
695 .check_async
= allow_async
,
700 pm_runtime_get_sync(dev
->parent
);
702 ret
= bus_for_each_drv(dev
->bus
, NULL
, &data
,
703 __device_attach_driver
);
704 if (!ret
&& allow_async
&& data
.have_async
) {
706 * If we could not find appropriate driver
707 * synchronously and we are allowed to do
708 * async probes and there are drivers that
709 * want to probe asynchronously, we'll
712 dev_dbg(dev
, "scheduling asynchronous probe\n");
714 async_schedule(__device_attach_async_helper
, dev
);
716 pm_request_idle(dev
);
720 pm_runtime_put(dev
->parent
);
728 * device_attach - try to attach device to a driver.
731 * Walk the list of drivers that the bus has and call
732 * driver_probe_device() for each pair. If a compatible
733 * pair is found, break out and return.
735 * Returns 1 if the device was bound to a driver;
736 * 0 if no matching driver was found;
737 * -ENODEV if the device is not registered.
739 * When called for a USB interface, @dev->parent lock must be held.
741 int device_attach(struct device
*dev
)
743 return __device_attach(dev
, false);
745 EXPORT_SYMBOL_GPL(device_attach
);
747 void device_initial_probe(struct device
*dev
)
749 __device_attach(dev
, true);
752 static int __driver_attach(struct device
*dev
, void *data
)
754 struct device_driver
*drv
= data
;
758 * Lock device and try to bind to it. We drop the error
759 * here and always return 0, because we need to keep trying
760 * to bind to devices and some drivers will return an error
761 * simply if it didn't support the device.
763 * driver_probe_device() will spit a warning if there
767 ret
= driver_match_device(drv
, dev
);
771 } else if (ret
== -EPROBE_DEFER
) {
772 dev_dbg(dev
, "Device match requests probe deferral\n");
773 driver_deferred_probe_add(dev
);
774 } else if (ret
< 0) {
775 dev_dbg(dev
, "Bus failed to match device: %d", ret
);
777 } /* ret > 0 means positive match */
779 if (dev
->parent
) /* Needed for USB */
780 device_lock(dev
->parent
);
783 driver_probe_device(drv
, dev
);
786 device_unlock(dev
->parent
);
792 * driver_attach - try to bind driver to devices.
795 * Walk the list of devices that the bus has on it and try to
796 * match the driver with each one. If driver_probe_device()
797 * returns 0 and the @dev->driver is set, we've found a
800 int driver_attach(struct device_driver
*drv
)
802 return bus_for_each_dev(drv
->bus
, NULL
, drv
, __driver_attach
);
804 EXPORT_SYMBOL_GPL(driver_attach
);
807 * __device_release_driver() must be called with @dev lock held.
808 * When called for a USB interface, @dev->parent lock must be held as well.
810 static void __device_release_driver(struct device
*dev
, struct device
*parent
)
812 struct device_driver
*drv
;
816 while (device_links_busy(dev
)) {
819 device_unlock(parent
);
821 device_links_unbind_consumers(dev
);
827 * A concurrent invocation of the same function might
828 * have released the driver successfully while this one
829 * was waiting, so check for that.
831 if (dev
->driver
!= drv
)
835 pm_runtime_get_sync(dev
);
836 pm_runtime_clean_up_links(dev
);
838 driver_sysfs_remove(dev
);
841 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
842 BUS_NOTIFY_UNBIND_DRIVER
,
845 pm_runtime_put_sync(dev
);
847 if (dev
->bus
&& dev
->bus
->remove
)
848 dev
->bus
->remove(dev
);
849 else if (drv
->remove
)
852 device_links_driver_cleanup(dev
);
854 devres_release_all(dev
);
855 dma_deconfigure(dev
);
857 dev_set_drvdata(dev
, NULL
);
858 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
859 dev
->pm_domain
->dismiss(dev
);
860 pm_runtime_reinit(dev
);
862 klist_remove(&dev
->p
->knode_driver
);
863 device_pm_check_callbacks(dev
);
865 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
866 BUS_NOTIFY_UNBOUND_DRIVER
,
869 kobject_uevent(&dev
->kobj
, KOBJ_UNBIND
);
873 void device_release_driver_internal(struct device
*dev
,
874 struct device_driver
*drv
,
875 struct device
*parent
)
881 if (!drv
|| drv
== dev
->driver
)
882 __device_release_driver(dev
, parent
);
886 device_unlock(parent
);
890 * device_release_driver - manually detach device from driver.
893 * Manually detach device from driver.
894 * When called for a USB interface, @dev->parent lock must be held.
896 * If this function is to be called with @dev->parent lock held, ensure that
897 * the device's consumers are unbound in advance or that their locks can be
898 * acquired under the @dev->parent lock.
900 void device_release_driver(struct device
*dev
)
903 * If anyone calls device_release_driver() recursively from
904 * within their ->remove callback for the same device, they
905 * will deadlock right here.
907 device_release_driver_internal(dev
, NULL
, NULL
);
909 EXPORT_SYMBOL_GPL(device_release_driver
);
912 * driver_detach - detach driver from all devices it controls.
915 void driver_detach(struct device_driver
*drv
)
917 struct device_private
*dev_prv
;
920 if (driver_allows_async_probing(drv
))
921 async_synchronize_full();
924 spin_lock(&drv
->p
->klist_devices
.k_lock
);
925 if (list_empty(&drv
->p
->klist_devices
.k_list
)) {
926 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
929 dev_prv
= list_entry(drv
->p
->klist_devices
.k_list
.prev
,
930 struct device_private
,
931 knode_driver
.n_node
);
932 dev
= dev_prv
->device
;
934 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
935 device_release_driver_internal(dev
, drv
, dev
->parent
);