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![Ulf Hansson](/assets/img/avatar_default.png)
There are two common expectations among several subsystems/drivers that deploys runtime PM support, but which isn't met by the driver core. Expectation 1) At ->probe() the subsystem/driver expects the runtime PM status of the device to be RPM_SUSPENDED, which is the initial status being assigned at device registration. This expectation is especially common among some of those subsystems/ drivers that manages devices with an attached PM domain, as those requires the ->runtime_resume() callback at the PM domain level to be invoked during ->probe(). Moreover these subsystems/drivers entirely relies on runtime PM resources being managed at the PM domain level, thus don't implement their own set of runtime PM callbacks. These are two scenarios that suffers from this unmet expectation. i) A failed ->probe() sequence requests probe deferral: ->probe() ... pm_runtime_enable() pm_runtime_get_sync() ... err: pm_runtime_put() pm_runtime_disable() ... As there are no guarantees that such sequence turns the runtime PM status of the device into RPM_SUSPENDED, the re-trying ->probe() may start with the status in RPM_ACTIVE. In such case the runtime PM core won't invoke the ->runtime_resume() callback because of a pm_runtime_get_sync(), as it considers the device to be already runtime resumed. ii) A driver re-bind sequence: At driver unbind, the subsystem/driver's >remove() callback invokes a sequence of runtime PM APIs, to undo actions during ->probe() and to put the device into low power state. ->remove() ... pm_runtime_put() pm_runtime_disable() ... Similar as in the failing ->probe() case, this sequence don't guarantee the runtime PM status of the device to turn into RPM_SUSPENDED. Trying to re-bind the driver thus causes the same issue as when re-trying ->probe(), in the probe deferral scenario. Expectation 2) Drivers that invokes the pm_runtime_irq_safe() API during ->probe(), triggers the runtime PM core to increase the usage count for the device's parent and permanently make it runtime resumed. The usage count is only dropped at device removal, which also allows it to be runtime suspended again. A re-trying ->probe() repeats the call to pm_runtime_irq_safe() and thus once more triggers the usage count of the device's parent to be increased. This leads to not only an imbalance issue of the usage count of the device's parent, but also to keep it runtime resumed permanently even if ->probe() fails. To address these issues, let's change the policy of the driver core to meet these expectations. More precisely, at ->probe() failures and driver unbind, restore the initial states of runtime PM. Although to still allow subsystem's to control PM for devices that doesn't ->probe() successfully, don't restore the initial states unless runtime PM is disabled. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Kevin Hilman <khilman@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
762 lines
20 KiB
C
762 lines
20 KiB
C
/*
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* drivers/base/dd.c - The core device/driver interactions.
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*
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* This file contains the (sometimes tricky) code that controls the
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* interactions between devices and drivers, which primarily includes
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* driver binding and unbinding.
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*
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* All of this code used to exist in drivers/base/bus.c, but was
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* relocated to here in the name of compartmentalization (since it wasn't
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* strictly code just for the 'struct bus_type'.
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*
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* Copyright (c) 2002-5 Patrick Mochel
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* Copyright (c) 2002-3 Open Source Development Labs
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* Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
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* Copyright (c) 2007-2009 Novell Inc.
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*
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* This file is released under the GPLv2
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*/
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#include <linux/device.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/wait.h>
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#include <linux/async.h>
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#include <linux/pm_runtime.h>
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#include <linux/pinctrl/devinfo.h>
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#include "base.h"
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#include "power/power.h"
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/*
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* Deferred Probe infrastructure.
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*
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* Sometimes driver probe order matters, but the kernel doesn't always have
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* dependency information which means some drivers will get probed before a
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* resource it depends on is available. For example, an SDHCI driver may
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* first need a GPIO line from an i2c GPIO controller before it can be
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* initialized. If a required resource is not available yet, a driver can
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* request probing to be deferred by returning -EPROBE_DEFER from its probe hook
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*
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* Deferred probe maintains two lists of devices, a pending list and an active
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* list. A driver returning -EPROBE_DEFER causes the device to be added to the
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* pending list. A successful driver probe will trigger moving all devices
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* from the pending to the active list so that the workqueue will eventually
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* retry them.
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*
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* The deferred_probe_mutex must be held any time the deferred_probe_*_list
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* of the (struct device*)->p->deferred_probe pointers are manipulated
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*/
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static DEFINE_MUTEX(deferred_probe_mutex);
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static LIST_HEAD(deferred_probe_pending_list);
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static LIST_HEAD(deferred_probe_active_list);
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static struct workqueue_struct *deferred_wq;
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static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
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/*
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* deferred_probe_work_func() - Retry probing devices in the active list.
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*/
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static void deferred_probe_work_func(struct work_struct *work)
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{
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struct device *dev;
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struct device_private *private;
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/*
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* This block processes every device in the deferred 'active' list.
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* Each device is removed from the active list and passed to
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* bus_probe_device() to re-attempt the probe. The loop continues
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* until every device in the active list is removed and retried.
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*
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* Note: Once the device is removed from the list and the mutex is
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* released, it is possible for the device get freed by another thread
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* and cause a illegal pointer dereference. This code uses
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* get/put_device() to ensure the device structure cannot disappear
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* from under our feet.
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*/
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mutex_lock(&deferred_probe_mutex);
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while (!list_empty(&deferred_probe_active_list)) {
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private = list_first_entry(&deferred_probe_active_list,
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typeof(*dev->p), deferred_probe);
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dev = private->device;
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list_del_init(&private->deferred_probe);
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get_device(dev);
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/*
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* Drop the mutex while probing each device; the probe path may
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* manipulate the deferred list
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*/
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mutex_unlock(&deferred_probe_mutex);
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/*
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* Force the device to the end of the dpm_list since
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* the PM code assumes that the order we add things to
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* the list is a good order for suspend but deferred
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* probe makes that very unsafe.
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*/
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device_pm_lock();
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device_pm_move_last(dev);
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device_pm_unlock();
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dev_dbg(dev, "Retrying from deferred list\n");
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bus_probe_device(dev);
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mutex_lock(&deferred_probe_mutex);
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put_device(dev);
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}
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mutex_unlock(&deferred_probe_mutex);
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}
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static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
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static void driver_deferred_probe_add(struct device *dev)
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{
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mutex_lock(&deferred_probe_mutex);
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if (list_empty(&dev->p->deferred_probe)) {
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dev_dbg(dev, "Added to deferred list\n");
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list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
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}
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mutex_unlock(&deferred_probe_mutex);
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}
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void driver_deferred_probe_del(struct device *dev)
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{
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mutex_lock(&deferred_probe_mutex);
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if (!list_empty(&dev->p->deferred_probe)) {
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dev_dbg(dev, "Removed from deferred list\n");
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list_del_init(&dev->p->deferred_probe);
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}
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mutex_unlock(&deferred_probe_mutex);
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}
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static bool driver_deferred_probe_enable = false;
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/**
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* driver_deferred_probe_trigger() - Kick off re-probing deferred devices
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*
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* This functions moves all devices from the pending list to the active
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* list and schedules the deferred probe workqueue to process them. It
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* should be called anytime a driver is successfully bound to a device.
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*
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* Note, there is a race condition in multi-threaded probe. In the case where
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* more than one device is probing at the same time, it is possible for one
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* probe to complete successfully while another is about to defer. If the second
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* depends on the first, then it will get put on the pending list after the
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* trigger event has already occurred and will be stuck there.
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*
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* The atomic 'deferred_trigger_count' is used to determine if a successful
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* trigger has occurred in the midst of probing a driver. If the trigger count
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* changes in the midst of a probe, then deferred processing should be triggered
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* again.
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*/
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static void driver_deferred_probe_trigger(void)
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{
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if (!driver_deferred_probe_enable)
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return;
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/*
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* A successful probe means that all the devices in the pending list
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* should be triggered to be reprobed. Move all the deferred devices
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* into the active list so they can be retried by the workqueue
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*/
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mutex_lock(&deferred_probe_mutex);
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atomic_inc(&deferred_trigger_count);
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list_splice_tail_init(&deferred_probe_pending_list,
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&deferred_probe_active_list);
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mutex_unlock(&deferred_probe_mutex);
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/*
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* Kick the re-probe thread. It may already be scheduled, but it is
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* safe to kick it again.
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*/
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queue_work(deferred_wq, &deferred_probe_work);
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}
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/**
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* deferred_probe_initcall() - Enable probing of deferred devices
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*
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* We don't want to get in the way when the bulk of drivers are getting probed.
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* Instead, this initcall makes sure that deferred probing is delayed until
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* late_initcall time.
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*/
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static int deferred_probe_initcall(void)
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{
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deferred_wq = create_singlethread_workqueue("deferwq");
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if (WARN_ON(!deferred_wq))
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return -ENOMEM;
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driver_deferred_probe_enable = true;
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driver_deferred_probe_trigger();
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/* Sort as many dependencies as possible before exiting initcalls */
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flush_workqueue(deferred_wq);
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return 0;
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}
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late_initcall(deferred_probe_initcall);
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static void driver_bound(struct device *dev)
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{
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if (klist_node_attached(&dev->p->knode_driver)) {
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printk(KERN_WARNING "%s: device %s already bound\n",
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__func__, kobject_name(&dev->kobj));
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return;
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}
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pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
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__func__, dev_name(dev));
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klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
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/*
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* Make sure the device is no longer in one of the deferred lists and
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* kick off retrying all pending devices
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*/
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driver_deferred_probe_del(dev);
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driver_deferred_probe_trigger();
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if (dev->bus)
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blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
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BUS_NOTIFY_BOUND_DRIVER, dev);
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}
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static int driver_sysfs_add(struct device *dev)
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{
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int ret;
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if (dev->bus)
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blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
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BUS_NOTIFY_BIND_DRIVER, dev);
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ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
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kobject_name(&dev->kobj));
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if (ret == 0) {
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ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
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"driver");
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if (ret)
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sysfs_remove_link(&dev->driver->p->kobj,
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kobject_name(&dev->kobj));
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}
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return ret;
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}
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static void driver_sysfs_remove(struct device *dev)
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{
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struct device_driver *drv = dev->driver;
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if (drv) {
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sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
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sysfs_remove_link(&dev->kobj, "driver");
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}
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}
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/**
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* device_bind_driver - bind a driver to one device.
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* @dev: device.
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*
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* Allow manual attachment of a driver to a device.
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* Caller must have already set @dev->driver.
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*
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* Note that this does not modify the bus reference count
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* nor take the bus's rwsem. Please verify those are accounted
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* for before calling this. (It is ok to call with no other effort
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* from a driver's probe() method.)
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*
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* This function must be called with the device lock held.
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*/
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int device_bind_driver(struct device *dev)
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{
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int ret;
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ret = driver_sysfs_add(dev);
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if (!ret)
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driver_bound(dev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(device_bind_driver);
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static atomic_t probe_count = ATOMIC_INIT(0);
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static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
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static int really_probe(struct device *dev, struct device_driver *drv)
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{
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int ret = 0;
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int local_trigger_count = atomic_read(&deferred_trigger_count);
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atomic_inc(&probe_count);
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pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
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drv->bus->name, __func__, drv->name, dev_name(dev));
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WARN_ON(!list_empty(&dev->devres_head));
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dev->driver = drv;
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/* If using pinctrl, bind pins now before probing */
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ret = pinctrl_bind_pins(dev);
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if (ret)
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goto probe_failed;
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if (driver_sysfs_add(dev)) {
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printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
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__func__, dev_name(dev));
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goto probe_failed;
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}
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if (dev->pm_domain && dev->pm_domain->activate) {
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ret = dev->pm_domain->activate(dev);
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if (ret)
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goto probe_failed;
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}
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/*
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* Ensure devices are listed in devices_kset in correct order
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* It's important to move Dev to the end of devices_kset before
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* calling .probe, because it could be recursive and parent Dev
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* should always go first
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*/
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devices_kset_move_last(dev);
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if (dev->bus->probe) {
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ret = dev->bus->probe(dev);
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if (ret)
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goto probe_failed;
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} else if (drv->probe) {
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ret = drv->probe(dev);
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if (ret)
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goto probe_failed;
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}
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pinctrl_init_done(dev);
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if (dev->pm_domain && dev->pm_domain->sync)
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dev->pm_domain->sync(dev);
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driver_bound(dev);
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ret = 1;
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pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
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drv->bus->name, __func__, dev_name(dev), drv->name);
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goto done;
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probe_failed:
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devres_release_all(dev);
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driver_sysfs_remove(dev);
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dev->driver = NULL;
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dev_set_drvdata(dev, NULL);
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if (dev->pm_domain && dev->pm_domain->dismiss)
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dev->pm_domain->dismiss(dev);
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pm_runtime_reinit(dev);
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switch (ret) {
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case -EPROBE_DEFER:
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/* Driver requested deferred probing */
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dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
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driver_deferred_probe_add(dev);
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/* Did a trigger occur while probing? Need to re-trigger if yes */
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if (local_trigger_count != atomic_read(&deferred_trigger_count))
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driver_deferred_probe_trigger();
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break;
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case -ENODEV:
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case -ENXIO:
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pr_debug("%s: probe of %s rejects match %d\n",
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drv->name, dev_name(dev), ret);
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break;
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default:
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/* driver matched but the probe failed */
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printk(KERN_WARNING
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"%s: probe of %s failed with error %d\n",
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drv->name, dev_name(dev), ret);
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}
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/*
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* Ignore errors returned by ->probe so that the next driver can try
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* its luck.
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*/
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ret = 0;
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done:
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atomic_dec(&probe_count);
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wake_up(&probe_waitqueue);
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return ret;
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}
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/**
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* driver_probe_done
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* Determine if the probe sequence is finished or not.
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*
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* Should somehow figure out how to use a semaphore, not an atomic variable...
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*/
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int driver_probe_done(void)
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{
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pr_debug("%s: probe_count = %d\n", __func__,
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atomic_read(&probe_count));
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if (atomic_read(&probe_count))
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return -EBUSY;
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return 0;
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}
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/**
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* wait_for_device_probe
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* Wait for device probing to be completed.
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*/
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void wait_for_device_probe(void)
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{
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/* wait for the known devices to complete their probing */
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wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
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async_synchronize_full();
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}
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EXPORT_SYMBOL_GPL(wait_for_device_probe);
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/**
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* driver_probe_device - attempt to bind device & driver together
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* @drv: driver to bind a device to
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* @dev: device to try to bind to the driver
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*
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* This function returns -ENODEV if the device is not registered,
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* 1 if the device is bound successfully and 0 otherwise.
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*
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* This function must be called with @dev lock held. When called for a
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* USB interface, @dev->parent lock must be held as well.
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*
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* If the device has a parent, runtime-resume the parent before driver probing.
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*/
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int driver_probe_device(struct device_driver *drv, struct device *dev)
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{
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int ret = 0;
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if (!device_is_registered(dev))
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return -ENODEV;
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pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
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drv->bus->name, __func__, dev_name(dev), drv->name);
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if (dev->parent)
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pm_runtime_get_sync(dev->parent);
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pm_runtime_barrier(dev);
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ret = really_probe(dev, drv);
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pm_request_idle(dev);
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if (dev->parent)
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pm_runtime_put(dev->parent);
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return ret;
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}
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bool driver_allows_async_probing(struct device_driver *drv)
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{
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switch (drv->probe_type) {
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case PROBE_PREFER_ASYNCHRONOUS:
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return true;
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case PROBE_FORCE_SYNCHRONOUS:
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return false;
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default:
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if (module_requested_async_probing(drv->owner))
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return true;
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return false;
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}
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}
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struct device_attach_data {
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struct device *dev;
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/*
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* Indicates whether we are are considering asynchronous probing or
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* not. Only initial binding after device or driver registration
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* (including deferral processing) may be done asynchronously, the
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* rest is always synchronous, as we expect it is being done by
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* request from userspace.
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*/
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bool check_async;
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/*
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* Indicates if we are binding synchronous or asynchronous drivers.
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* When asynchronous probing is enabled we'll execute 2 passes
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* over drivers: first pass doing synchronous probing and second
|
|
* doing asynchronous probing (if synchronous did not succeed -
|
|
* most likely because there was no driver requiring synchronous
|
|
* probing - and we found asynchronous driver during first pass).
|
|
* The 2 passes are done because we can't shoot asynchronous
|
|
* probe for given device and driver from bus_for_each_drv() since
|
|
* driver pointer is not guaranteed to stay valid once
|
|
* bus_for_each_drv() iterates to the next driver on the bus.
|
|
*/
|
|
bool want_async;
|
|
|
|
/*
|
|
* We'll set have_async to 'true' if, while scanning for matching
|
|
* driver, we'll encounter one that requests asynchronous probing.
|
|
*/
|
|
bool have_async;
|
|
};
|
|
|
|
static int __device_attach_driver(struct device_driver *drv, void *_data)
|
|
{
|
|
struct device_attach_data *data = _data;
|
|
struct device *dev = data->dev;
|
|
bool async_allowed;
|
|
|
|
/*
|
|
* Check if device has already been claimed. This may
|
|
* happen with driver loading, device discovery/registration,
|
|
* and deferred probe processing happens all at once with
|
|
* multiple threads.
|
|
*/
|
|
if (dev->driver)
|
|
return -EBUSY;
|
|
|
|
if (!driver_match_device(drv, dev))
|
|
return 0;
|
|
|
|
async_allowed = driver_allows_async_probing(drv);
|
|
|
|
if (async_allowed)
|
|
data->have_async = true;
|
|
|
|
if (data->check_async && async_allowed != data->want_async)
|
|
return 0;
|
|
|
|
return driver_probe_device(drv, dev);
|
|
}
|
|
|
|
static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
|
|
{
|
|
struct device *dev = _dev;
|
|
struct device_attach_data data = {
|
|
.dev = dev,
|
|
.check_async = true,
|
|
.want_async = true,
|
|
};
|
|
|
|
device_lock(dev);
|
|
|
|
if (dev->parent)
|
|
pm_runtime_get_sync(dev->parent);
|
|
|
|
bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
|
|
dev_dbg(dev, "async probe completed\n");
|
|
|
|
pm_request_idle(dev);
|
|
|
|
if (dev->parent)
|
|
pm_runtime_put(dev->parent);
|
|
|
|
device_unlock(dev);
|
|
|
|
put_device(dev);
|
|
}
|
|
|
|
static int __device_attach(struct device *dev, bool allow_async)
|
|
{
|
|
int ret = 0;
|
|
|
|
device_lock(dev);
|
|
if (dev->driver) {
|
|
if (klist_node_attached(&dev->p->knode_driver)) {
|
|
ret = 1;
|
|
goto out_unlock;
|
|
}
|
|
ret = device_bind_driver(dev);
|
|
if (ret == 0)
|
|
ret = 1;
|
|
else {
|
|
dev->driver = NULL;
|
|
ret = 0;
|
|
}
|
|
} else {
|
|
struct device_attach_data data = {
|
|
.dev = dev,
|
|
.check_async = allow_async,
|
|
.want_async = false,
|
|
};
|
|
|
|
if (dev->parent)
|
|
pm_runtime_get_sync(dev->parent);
|
|
|
|
ret = bus_for_each_drv(dev->bus, NULL, &data,
|
|
__device_attach_driver);
|
|
if (!ret && allow_async && data.have_async) {
|
|
/*
|
|
* If we could not find appropriate driver
|
|
* synchronously and we are allowed to do
|
|
* async probes and there are drivers that
|
|
* want to probe asynchronously, we'll
|
|
* try them.
|
|
*/
|
|
dev_dbg(dev, "scheduling asynchronous probe\n");
|
|
get_device(dev);
|
|
async_schedule(__device_attach_async_helper, dev);
|
|
} else {
|
|
pm_request_idle(dev);
|
|
}
|
|
|
|
if (dev->parent)
|
|
pm_runtime_put(dev->parent);
|
|
}
|
|
out_unlock:
|
|
device_unlock(dev);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* device_attach - try to attach device to a driver.
|
|
* @dev: device.
|
|
*
|
|
* Walk the list of drivers that the bus has and call
|
|
* driver_probe_device() for each pair. If a compatible
|
|
* pair is found, break out and return.
|
|
*
|
|
* Returns 1 if the device was bound to a driver;
|
|
* 0 if no matching driver was found;
|
|
* -ENODEV if the device is not registered.
|
|
*
|
|
* When called for a USB interface, @dev->parent lock must be held.
|
|
*/
|
|
int device_attach(struct device *dev)
|
|
{
|
|
return __device_attach(dev, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(device_attach);
|
|
|
|
void device_initial_probe(struct device *dev)
|
|
{
|
|
__device_attach(dev, true);
|
|
}
|
|
|
|
static int __driver_attach(struct device *dev, void *data)
|
|
{
|
|
struct device_driver *drv = data;
|
|
|
|
/*
|
|
* Lock device and try to bind to it. We drop the error
|
|
* here and always return 0, because we need to keep trying
|
|
* to bind to devices and some drivers will return an error
|
|
* simply if it didn't support the device.
|
|
*
|
|
* driver_probe_device() will spit a warning if there
|
|
* is an error.
|
|
*/
|
|
|
|
if (!driver_match_device(drv, dev))
|
|
return 0;
|
|
|
|
if (dev->parent) /* Needed for USB */
|
|
device_lock(dev->parent);
|
|
device_lock(dev);
|
|
if (!dev->driver)
|
|
driver_probe_device(drv, dev);
|
|
device_unlock(dev);
|
|
if (dev->parent)
|
|
device_unlock(dev->parent);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* driver_attach - try to bind driver to devices.
|
|
* @drv: driver.
|
|
*
|
|
* Walk the list of devices that the bus has on it and try to
|
|
* match the driver with each one. If driver_probe_device()
|
|
* returns 0 and the @dev->driver is set, we've found a
|
|
* compatible pair.
|
|
*/
|
|
int driver_attach(struct device_driver *drv)
|
|
{
|
|
return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
|
|
}
|
|
EXPORT_SYMBOL_GPL(driver_attach);
|
|
|
|
/*
|
|
* __device_release_driver() must be called with @dev lock held.
|
|
* When called for a USB interface, @dev->parent lock must be held as well.
|
|
*/
|
|
static void __device_release_driver(struct device *dev)
|
|
{
|
|
struct device_driver *drv;
|
|
|
|
drv = dev->driver;
|
|
if (drv) {
|
|
if (driver_allows_async_probing(drv))
|
|
async_synchronize_full();
|
|
|
|
pm_runtime_get_sync(dev);
|
|
|
|
driver_sysfs_remove(dev);
|
|
|
|
if (dev->bus)
|
|
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
|
|
BUS_NOTIFY_UNBIND_DRIVER,
|
|
dev);
|
|
|
|
pm_runtime_put_sync(dev);
|
|
|
|
if (dev->bus && dev->bus->remove)
|
|
dev->bus->remove(dev);
|
|
else if (drv->remove)
|
|
drv->remove(dev);
|
|
devres_release_all(dev);
|
|
dev->driver = NULL;
|
|
dev_set_drvdata(dev, NULL);
|
|
if (dev->pm_domain && dev->pm_domain->dismiss)
|
|
dev->pm_domain->dismiss(dev);
|
|
pm_runtime_reinit(dev);
|
|
|
|
klist_remove(&dev->p->knode_driver);
|
|
if (dev->bus)
|
|
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
|
|
BUS_NOTIFY_UNBOUND_DRIVER,
|
|
dev);
|
|
|
|
}
|
|
}
|
|
|
|
/**
|
|
* device_release_driver - manually detach device from driver.
|
|
* @dev: device.
|
|
*
|
|
* Manually detach device from driver.
|
|
* When called for a USB interface, @dev->parent lock must be held.
|
|
*/
|
|
void device_release_driver(struct device *dev)
|
|
{
|
|
/*
|
|
* If anyone calls device_release_driver() recursively from
|
|
* within their ->remove callback for the same device, they
|
|
* will deadlock right here.
|
|
*/
|
|
device_lock(dev);
|
|
__device_release_driver(dev);
|
|
device_unlock(dev);
|
|
}
|
|
EXPORT_SYMBOL_GPL(device_release_driver);
|
|
|
|
/**
|
|
* driver_detach - detach driver from all devices it controls.
|
|
* @drv: driver.
|
|
*/
|
|
void driver_detach(struct device_driver *drv)
|
|
{
|
|
struct device_private *dev_prv;
|
|
struct device *dev;
|
|
|
|
for (;;) {
|
|
spin_lock(&drv->p->klist_devices.k_lock);
|
|
if (list_empty(&drv->p->klist_devices.k_list)) {
|
|
spin_unlock(&drv->p->klist_devices.k_lock);
|
|
break;
|
|
}
|
|
dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
|
|
struct device_private,
|
|
knode_driver.n_node);
|
|
dev = dev_prv->device;
|
|
get_device(dev);
|
|
spin_unlock(&drv->p->klist_devices.k_lock);
|
|
|
|
if (dev->parent) /* Needed for USB */
|
|
device_lock(dev->parent);
|
|
device_lock(dev);
|
|
if (dev->driver == drv)
|
|
__device_release_driver(dev);
|
|
device_unlock(dev);
|
|
if (dev->parent)
|
|
device_unlock(dev->parent);
|
|
put_device(dev);
|
|
}
|
|
}
|