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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * drivers/base/dd.c - The core device/driver interactions.
  *
  * This file contains the (sometimes tricky) code that controls the
  * interactions between devices and drivers, which primarily includes
  * driver binding and unbinding.
  *
  * All of this code used to exist in drivers/base/bus.c, but was
  * relocated to here in the name of compartmentalization (since it wasn't
  * strictly code just for the 'struct bus_type'.
  *
  * Copyright (c) 2002-5 Patrick Mochel
  * Copyright (c) 2002-3 Open Source Development Labs
  * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
  * Copyright (c) 2007-2009 Novell Inc.
  */
 
 #include <linux/debugfs.h>
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/dma-map-ops.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/async.h>
 #include <linux/pm_runtime.h>
 #include <linux/pinctrl/devinfo.h>
 #include <linux/slab.h>
 
 #include "base.h"
 #include "power/power.h"
 
 /*
  * Deferred Probe infrastructure.
  *
  * Sometimes driver probe order matters, but the kernel doesn't always have
  * dependency information which means some drivers will get probed before a
  * resource it depends on is available.  For example, an SDHCI driver may
  * first need a GPIO line from an i2c GPIO controller before it can be
  * initialized.  If a required resource is not available yet, a driver can
  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
  *
  * Deferred probe maintains two lists of devices, a pending list and an active
  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
  * pending list.  A successful driver probe will trigger moving all devices
  * from the pending to the active list so that the workqueue will eventually
  * retry them.
  *
  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
  * of the (struct device*)->p->deferred_probe pointers are manipulated
  */
 static DEFINE_MUTEX(deferred_probe_mutex);
 static LIST_HEAD(deferred_probe_pending_list);
 static LIST_HEAD(deferred_probe_active_list);
 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
 static bool initcalls_done;
 
 /* Save the async probe drivers' name from kernel cmdline */
 #define ASYNC_DRV_NAMES_MAX_LEN 256
 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
 static bool async_probe_default;
 
 /*
  * In some cases, like suspend to RAM or hibernation, It might be reasonable
  * to prohibit probing of devices as it could be unsafe.
  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
  */
 static bool defer_all_probes;
 
 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
 {
     kfree(dev->p->deferred_probe_reason);
     dev->p->deferred_probe_reason = reason;
 }
 
 /*
  * deferred_probe_work_func() - Retry probing devices in the active list.
  */
 static void deferred_probe_work_func(struct work_struct *work)
 {
     struct device *dev;
     struct device_private *private;
     /*
      * This block processes every device in the deferred 'active' list.
      * Each device is removed from the active list and passed to
      * bus_probe_device() to re-attempt the probe.  The loop continues
      * until every device in the active list is removed and retried.
      *
      * Note: Once the device is removed from the list and the mutex is
      * released, it is possible for the device get freed by another thread
      * and cause a illegal pointer dereference.  This code uses
      * get/put_device() to ensure the device structure cannot disappear
      * from under our feet.
      */
     mutex_lock(&deferred_probe_mutex);
     while (!list_empty(&deferred_probe_active_list)) {
         private = list_first_entry(&deferred_probe_active_list,
                     typeof(*dev->p), deferred_probe);
         dev = private->device;
         list_del_init(&private->deferred_probe);
 
         get_device(dev);
 
         __device_set_deferred_probe_reason(dev, NULL);
 
         /*
          * Drop the mutex while probing each device; the probe path may
          * manipulate the deferred list
          */
         mutex_unlock(&deferred_probe_mutex);
 
         /*
          * Force the device to the end of the dpm_list since
          * the PM code assumes that the order we add things to
          * the list is a good order for suspend but deferred
          * probe makes that very unsafe.
          */
         device_pm_move_to_tail(dev);
 
         dev_dbg(dev, "Retrying from deferred list\n");
         bus_probe_device(dev);
         mutex_lock(&deferred_probe_mutex);
 
         put_device(dev);
     }
     mutex_unlock(&deferred_probe_mutex);
 }
 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
 
 void driver_deferred_probe_add(struct device *dev)
 {
     if (!dev->can_match)
         return;
 
     mutex_lock(&deferred_probe_mutex);
     if (list_empty(&dev->p->deferred_probe)) {
         dev_dbg(dev, "Added to deferred list\n");
         list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
     }
     mutex_unlock(&deferred_probe_mutex);
 }
 
 void driver_deferred_probe_del(struct device *dev)
 {
     mutex_lock(&deferred_probe_mutex);
     if (!list_empty(&dev->p->deferred_probe)) {
         dev_dbg(dev, "Removed from deferred list\n");
         list_del_init(&dev->p->deferred_probe);
         __device_set_deferred_probe_reason(dev, NULL);
     }
     mutex_unlock(&deferred_probe_mutex);
 }
 
 static bool driver_deferred_probe_enable;
 /**
  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
  *
  * This functions moves all devices from the pending list to the active
  * list and schedules the deferred probe workqueue to process them.  It
  * should be called anytime a driver is successfully bound to a device.
  *
  * Note, there is a race condition in multi-threaded probe. In the case where
  * more than one device is probing at the same time, it is possible for one
  * probe to complete successfully while another is about to defer. If the second
  * depends on the first, then it will get put on the pending list after the
  * trigger event has already occurred and will be stuck there.
  *
  * The atomic 'deferred_trigger_count' is used to determine if a successful
  * trigger has occurred in the midst of probing a driver. If the trigger count
  * changes in the midst of a probe, then deferred processing should be triggered
  * again.
  */
 void driver_deferred_probe_trigger(void)
 {
     if (!driver_deferred_probe_enable)
         return;
 
     /*
      * A successful probe means that all the devices in the pending list
      * should be triggered to be reprobed.  Move all the deferred devices
      * into the active list so they can be retried by the workqueue
      */
     mutex_lock(&deferred_probe_mutex);
     atomic_inc(&deferred_trigger_count);
     list_splice_tail_init(&deferred_probe_pending_list,
                   &deferred_probe_active_list);
     mutex_unlock(&deferred_probe_mutex);
 
     /*
      * Kick the re-probe thread.  It may already be scheduled, but it is
      * safe to kick it again.
      */
     queue_work(system_unbound_wq, &deferred_probe_work);
 }
 
 /**
  * device_block_probing() - Block/defer device's probes
  *
  *  It will disable probing of devices and defer their probes instead.
  */
 void device_block_probing(void)
 {
     defer_all_probes = true;
     /* sync with probes to avoid races. */
     wait_for_device_probe();
 }
 
 /**
  * device_unblock_probing() - Unblock/enable device's probes
  *
  *  It will restore normal behavior and trigger re-probing of deferred
  * devices.
  */
 void device_unblock_probing(void)
 {
     defer_all_probes = false;
     driver_deferred_probe_trigger();
 }
 
 /**
  * device_set_deferred_probe_reason() - Set defer probe reason message for device
  * @dev: the pointer to the struct device
  * @vaf: the pointer to va_format structure with message
  */
 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
 {
     const char *drv = dev_driver_string(dev);
     char *reason;
 
     mutex_lock(&deferred_probe_mutex);
 
     reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
     __device_set_deferred_probe_reason(dev, reason);
 
     mutex_unlock(&deferred_probe_mutex);
 }
 
 /*
  * deferred_devs_show() - Show the devices in the deferred probe pending list.
  */
 static int deferred_devs_show(struct seq_file *s, void *data)
 {
     struct device_private *curr;
 
     mutex_lock(&deferred_probe_mutex);
 
     list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
         seq_printf(s, "%s\t%s", dev_name(curr->device),
                curr->device->p->deferred_probe_reason ?: "\n");
 
     mutex_unlock(&deferred_probe_mutex);
 
     return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
 
 #ifdef CONFIG_MODULES
 int driver_deferred_probe_timeout = 10;
 #else
 int driver_deferred_probe_timeout;
 #endif
 
 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
 
 static int __init deferred_probe_timeout_setup(char *str)
 {
     int timeout;
 
     if (!kstrtoint(str, 10, &timeout))
         driver_deferred_probe_timeout = timeout;
     return 1;
 }
 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
 
 /**
  * driver_deferred_probe_check_state() - Check deferred probe state
  * @dev: device to check
  *
  * Return:
  * * -ENODEV if initcalls have completed and modules are disabled.
  * * -ETIMEDOUT if the deferred probe timeout was set and has expired
  *   and modules are enabled.
  * * -EPROBE_DEFER in other cases.
  *
  * Drivers or subsystems can opt-in to calling this function instead of directly
  * returning -EPROBE_DEFER.
  */
 int driver_deferred_probe_check_state(struct device *dev)
 {
     if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
         dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
         return -ENODEV;
     }
 
     if (!driver_deferred_probe_timeout && initcalls_done) {
         dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
         return -ETIMEDOUT;
     }
 
     return -EPROBE_DEFER;
 }
 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
 
 static void deferred_probe_timeout_work_func(struct work_struct *work)
 {
     struct device_private *p;
 
     fw_devlink_drivers_done();
 
     driver_deferred_probe_timeout = 0;
     driver_deferred_probe_trigger();
     flush_work(&deferred_probe_work);
 
     mutex_lock(&deferred_probe_mutex);
     list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
         dev_info(p->device, "deferred probe pending\n");
     mutex_unlock(&deferred_probe_mutex);
 }
 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
 
 void deferred_probe_extend_timeout(void)
 {
     /*
      * If the work hasn't been queued yet or if the work expired, don't
      * start a new one.
      */
     if (cancel_delayed_work(&deferred_probe_timeout_work)) {
         schedule_delayed_work(&deferred_probe_timeout_work,
                 driver_deferred_probe_timeout * HZ);
         pr_debug("Extended deferred probe timeout by %d secs\n",
                     driver_deferred_probe_timeout);
     }
 }
 
 /**
  * deferred_probe_initcall() - Enable probing of deferred devices
  *
  * We don't want to get in the way when the bulk of drivers are getting probed.
  * Instead, this initcall makes sure that deferred probing is delayed until
  * late_initcall time.
  */
 static int deferred_probe_initcall(void)
 {
     debugfs_create_file("devices_deferred", 0444, NULL, NULL,
                 &deferred_devs_fops);
 
     driver_deferred_probe_enable = true;
     driver_deferred_probe_trigger();
     /* Sort as many dependencies as possible before exiting initcalls */
     flush_work(&deferred_probe_work);
     initcalls_done = true;
 
     if (!IS_ENABLED(CONFIG_MODULES))
         fw_devlink_drivers_done();
 
     /*
      * Trigger deferred probe again, this time we won't defer anything
      * that is optional
      */
     driver_deferred_probe_trigger();
     flush_work(&deferred_probe_work);
 
     if (driver_deferred_probe_timeout > 0) {
         schedule_delayed_work(&deferred_probe_timeout_work,
             driver_deferred_probe_timeout * HZ);
     }
     return 0;
 }
 late_initcall(deferred_probe_initcall);
 
 static void __exit deferred_probe_exit(void)
 {
     debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
 }
 __exitcall(deferred_probe_exit);
 
 /**
  * device_is_bound() - Check if device is bound to a driver
  * @dev: device to check
  *
  * Returns true if passed device has already finished probing successfully
  * against a driver.
  *
  * This function must be called with the device lock held.
  */
 bool device_is_bound(struct device *dev)
 {
     return dev->p && klist_node_attached(&dev->p->knode_driver);
 }
 
 static void driver_bound(struct device *dev)
 {
     if (device_is_bound(dev)) {
         pr_warn("%s: device %s already bound\n",
             __func__, kobject_name(&dev->kobj));
         return;
     }
 
     pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
          __func__, dev_name(dev));
 
     klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
     device_links_driver_bound(dev);
 
     device_pm_check_callbacks(dev);
 
     /*
      * Make sure the device is no longer in one of the deferred lists and
      * kick off retrying all pending devices
      */
     driver_deferred_probe_del(dev);
     driver_deferred_probe_trigger();
 
     if (dev->bus)
         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                          BUS_NOTIFY_BOUND_DRIVER, dev);
 
     kobject_uevent(&dev->kobj, KOBJ_BIND);
 }
 
 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
                 const char *buf, size_t count)
 {
     device_lock(dev);
     dev->driver->coredump(dev);
     device_unlock(dev);
 
     return count;
 }
 static DEVICE_ATTR_WO(coredump);
 
 static int driver_sysfs_add(struct device *dev)
 {
     int ret;
 
     if (dev->bus)
         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                          BUS_NOTIFY_BIND_DRIVER, dev);
 
     ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
                 kobject_name(&dev->kobj));
     if (ret)
         goto fail;
 
     ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
                 "driver");
     if (ret)
         goto rm_dev;
 
     if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
         return 0;
 
     ret = device_create_file(dev, &dev_attr_coredump);
     if (!ret)
         return 0;
 
     sysfs_remove_link(&dev->kobj, "driver");
 
 rm_dev:
     sysfs_remove_link(&dev->driver->p->kobj,
               kobject_name(&dev->kobj));
 
 fail:
     return ret;
 }
 
 static void driver_sysfs_remove(struct device *dev)
 {
     struct device_driver *drv = dev->driver;
 
     if (drv) {
         if (drv->coredump)
             device_remove_file(dev, &dev_attr_coredump);
         sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
         sysfs_remove_link(&dev->kobj, "driver");
     }
 }
 
 /**
  * device_bind_driver - bind a driver to one device.
  * @dev: device.
  *
  * Allow manual attachment of a driver to a device.
  * Caller must have already set @dev->driver.
  *
  * Note that this does not modify the bus reference count.
  * Please verify that is accounted for before calling this.
  * (It is ok to call with no other effort from a driver's probe() method.)
  *
  * This function must be called with the device lock held.
  *
  * Callers should prefer to use device_driver_attach() instead.
  */
 int device_bind_driver(struct device *dev)
 {
     int ret;
 
     ret = driver_sysfs_add(dev);
     if (!ret) {
         device_links_force_bind(dev);
         driver_bound(dev);
     }
     else if (dev->bus)
         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                          BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
     return ret;
 }
 EXPORT_SYMBOL_GPL(device_bind_driver);
 
 static atomic_t probe_count = ATOMIC_INIT(0);
 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 
 static ssize_t state_synced_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
 {
     bool val;
 
     device_lock(dev);
     val = dev->state_synced;
     device_unlock(dev);
 
     return sysfs_emit(buf, "%u\n", val);
 }
 static DEVICE_ATTR_RO(state_synced);
 
 static void device_unbind_cleanup(struct device *dev)
 {
     devres_release_all(dev);
     arch_teardown_dma_ops(dev);
     kfree(dev->dma_range_map);
     dev->dma_range_map = NULL;
     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);
     dev_pm_set_driver_flags(dev, 0);
 }
 
 static void device_remove(struct device *dev)
 {
     device_remove_file(dev, &dev_attr_state_synced);
     device_remove_groups(dev, dev->driver->dev_groups);
 
     if (dev->bus && dev->bus->remove)
         dev->bus->remove(dev);
     else if (dev->driver->remove)
         dev->driver->remove(dev);
 }
 
 static int call_driver_probe(struct device *dev, struct device_driver *drv)
 {
     int ret = 0;
 
     if (dev->bus->probe)
         ret = dev->bus->probe(dev);
     else if (drv->probe)
         ret = drv->probe(dev);
 
     switch (ret) {
     case 0:
         break;
     case -EPROBE_DEFER:
         /* Driver requested deferred probing */
         dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
         break;
     case -ENODEV:
     case -ENXIO:
         pr_debug("%s: probe of %s rejects match %d\n",
              drv->name, dev_name(dev), ret);
         break;
     default:
         /* driver matched but the probe failed */
         pr_warn("%s: probe of %s failed with error %d\n",
             drv->name, dev_name(dev), ret);
         break;
     }
 
     return ret;
 }
 
 static int really_probe(struct device *dev, struct device_driver *drv)
 {
     bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
                !drv->suppress_bind_attrs;
     int ret, link_ret;
 
     if (defer_all_probes) {
         /*
          * Value of defer_all_probes can be set only by
          * device_block_probing() which, in turn, will call
          * wait_for_device_probe() right after that to avoid any races.
          */
         dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
         return -EPROBE_DEFER;
     }
 
     link_ret = device_links_check_suppliers(dev);
     if (link_ret == -EPROBE_DEFER)
         return link_ret;
 
     pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
          drv->bus->name, __func__, drv->name, dev_name(dev));
     if (!list_empty(&dev->devres_head)) {
         dev_crit(dev, "Resources present before probing\n");
         ret = -EBUSY;
         goto done;
     }
 
 re_probe:
     dev->driver = drv;
 
     /* If using pinctrl, bind pins now before probing */
     ret = pinctrl_bind_pins(dev);
     if (ret)
         goto pinctrl_bind_failed;
 
     if (dev->bus->dma_configure) {
         ret = dev->bus->dma_configure(dev);
         if (ret)
             goto pinctrl_bind_failed;
     }
 
     ret = driver_sysfs_add(dev);
     if (ret) {
         pr_err("%s: driver_sysfs_add(%s) failed\n",
                __func__, dev_name(dev));
         goto sysfs_failed;
     }
 
     if (dev->pm_domain && dev->pm_domain->activate) {
         ret = dev->pm_domain->activate(dev);
         if (ret)
             goto probe_failed;
     }
 
     ret = call_driver_probe(dev, drv);
     if (ret) {
         /*
          * If fw_devlink_best_effort is active (denoted by -EAGAIN), the
          * device might actually probe properly once some of its missing
          * suppliers have probed. So, treat this as if the driver
          * returned -EPROBE_DEFER.
          */
         if (link_ret == -EAGAIN)
             ret = -EPROBE_DEFER;
 
         /*
          * Return probe errors as positive values so that the callers
          * can distinguish them from other errors.
          */
         ret = -ret;
         goto probe_failed;
     }
 
     ret = device_add_groups(dev, drv->dev_groups);
     if (ret) {
         dev_err(dev, "device_add_groups() failed\n");
         goto dev_groups_failed;
     }
 
     if (dev_has_sync_state(dev)) {
         ret = device_create_file(dev, &dev_attr_state_synced);
         if (ret) {
             dev_err(dev, "state_synced sysfs add failed\n");
             goto dev_sysfs_state_synced_failed;
         }
     }
 
     if (test_remove) {
         test_remove = false;
 
         device_remove(dev);
         driver_sysfs_remove(dev);
         device_unbind_cleanup(dev);
 
         goto re_probe;
     }
 
     pinctrl_init_done(dev);
 
     if (dev->pm_domain && dev->pm_domain->sync)
         dev->pm_domain->sync(dev);
 
     driver_bound(dev);
     pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
          drv->bus->name, __func__, dev_name(dev), drv->name);
     goto done;
 
 dev_sysfs_state_synced_failed:
 dev_groups_failed:
     device_remove(dev);
 probe_failed:
     driver_sysfs_remove(dev);
 sysfs_failed:
     if (dev->bus)
         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                          BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
     if (dev->bus && dev->bus->dma_cleanup)
         dev->bus->dma_cleanup(dev);
 pinctrl_bind_failed:
     device_links_no_driver(dev);
     device_unbind_cleanup(dev);
 done:
     return ret;
 }
 
 /*
  * For initcall_debug, show the driver probe time.
  */
 static int really_probe_debug(struct device *dev, struct device_driver *drv)
 {
     ktime_t calltime, rettime;
     int ret;
 
     calltime = ktime_get();
     ret = really_probe(dev, drv);
     rettime = ktime_get();
     pr_debug("probe of %s returned %d after %lld usecs\n",
          dev_name(dev), ret, ktime_us_delta(rettime, calltime));
     return ret;
 }
 
 /**
  * driver_probe_done
  * Determine if the probe sequence is finished or not.
  *
  * Should somehow figure out how to use a semaphore, not an atomic variable...
  */
 int driver_probe_done(void)
 {
     int local_probe_count = atomic_read(&probe_count);
 
     pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
     if (local_probe_count)
         return -EBUSY;
     return 0;
 }
 
 /**
  * wait_for_device_probe
  * Wait for device probing to be completed.
  */
 void wait_for_device_probe(void)
 {
     /* wait for the deferred probe workqueue to finish */
     flush_work(&deferred_probe_work);
 
     /* wait for the known devices to complete their probing */
     wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
     async_synchronize_full();
 }
 EXPORT_SYMBOL_GPL(wait_for_device_probe);
 
 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
 {
     int ret = 0;
 
     if (dev->p->dead || !device_is_registered(dev))
         return -ENODEV;
     if (dev->driver)
         return -EBUSY;
 
     dev->can_match = true;
     pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
          drv->bus->name, __func__, dev_name(dev), drv->name);
 
     pm_runtime_get_suppliers(dev);
     if (dev->parent)
         pm_runtime_get_sync(dev->parent);
 
     pm_runtime_barrier(dev);
     if (initcall_debug)
         ret = really_probe_debug(dev, drv);
     else
         ret = really_probe(dev, drv);
     pm_request_idle(dev);
 
     if (dev->parent)
         pm_runtime_put(dev->parent);
 
     pm_runtime_put_suppliers(dev);
     return ret;
 }
 
 /**
  * driver_probe_device - attempt to bind device & driver together
  * @drv: driver to bind a device to
  * @dev: device to try to bind to the driver
  *
  * This function returns -ENODEV if the device is not registered, -EBUSY if it
  * already has a driver, 0 if the device is bound successfully and a positive
  * (inverted) error code for failures from the ->probe method.
  *
  * This function must be called with @dev lock held.  When called for a
  * USB interface, @dev->parent lock must be held as well.
  *
  * If the device has a parent, runtime-resume the parent before driver probing.
  */
 static int driver_probe_device(struct device_driver *drv, struct device *dev)
 {
     int trigger_count = atomic_read(&deferred_trigger_count);
     int ret;
 
     atomic_inc(&probe_count);
     ret = __driver_probe_device(drv, dev);
     if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
         driver_deferred_probe_add(dev);
 
         /*
          * Did a trigger occur while probing? Need to re-trigger if yes
          */
         if (trigger_count != atomic_read(&deferred_trigger_count) &&
             !defer_all_probes)
             driver_deferred_probe_trigger();
     }
     atomic_dec(&probe_count);
     wake_up_all(&probe_waitqueue);
     return ret;
 }
 
 static inline bool cmdline_requested_async_probing(const char *drv_name)
 {
     bool async_drv;
 
     async_drv = parse_option_str(async_probe_drv_names, drv_name);
 
     return (async_probe_default != async_drv);
 }
 
 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
 static int __init save_async_options(char *buf)
 {
     if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
         pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
 
     strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
     async_probe_default = parse_option_str(async_probe_drv_names, "*");
 
     return 1;
 }
 __setup("driver_async_probe=", save_async_options);
 
 bool driver_allows_async_probing(struct device_driver *drv)
 {
     switch (drv->probe_type) {
     case PROBE_PREFER_ASYNCHRONOUS:
         return true;
 
     case PROBE_FORCE_SYNCHRONOUS:
         return false;
 
     default:
         if (cmdline_requested_async_probing(drv->name))
             return true;
 
         if (module_requested_async_probing(drv->owner))
             return true;
 
         return false;
     }
 }
 
 struct device_attach_data {
     struct device *dev;
 
     /*
      * Indicates whether we are considering asynchronous probing or
      * not. Only initial binding after device or driver registration
      * (including deferral processing) may be done asynchronously, the
      * rest is always synchronous, as we expect it is being done by
      * request from userspace.
      */
     bool check_async;
 
     /*
      * Indicates if we are binding synchronous or asynchronous drivers.
      * When asynchronous probing is enabled we'll execute 2 passes
      * 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;
     int ret;
 
     ret = driver_match_device(drv, dev);
     if (ret == 0) {
         /* no match */
         return 0;
     } else if (ret == -EPROBE_DEFER) {
         dev_dbg(dev, "Device match requests probe deferral\n");
         dev->can_match = true;
         driver_deferred_probe_add(dev);
         /*
          * Device can't match with a driver right now, so don't attempt
          * to match or bind with other drivers on the bus.
          */
         return ret;
     } else if (ret < 0) {
         dev_dbg(dev, "Bus failed to match device: %d\n", ret);
         return ret;
     } /* ret > 0 means positive match */
 
     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;
 
     /*
      * Ignore errors returned by ->probe so that the next driver can try
      * its luck.
      */
     ret = driver_probe_device(drv, dev);
     if (ret < 0)
         return ret;
     return ret == 0;
 }
 
 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);
 
     /*
      * Check if device has already been removed or claimed. This may
      * happen with driver loading, device discovery/registration,
      * and deferred probe processing happens all at once with
      * multiple threads.
      */
     if (dev->p->dead || dev->driver)
         goto out_unlock;
 
     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);
 out_unlock:
     device_unlock(dev);
 
     put_device(dev);
 }
 
 static int __device_attach(struct device *dev, bool allow_async)
 {
     int ret = 0;
     bool async = false;
 
     device_lock(dev);
     if (dev->p->dead) {
         goto out_unlock;
     } else if (dev->driver) {
         if (device_is_bound(dev)) {
             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 = true;
         } else {
             pm_request_idle(dev);
         }
 
         if (dev->parent)
             pm_runtime_put(dev->parent);
     }
 out_unlock:
     device_unlock(dev);
     if (async)
         async_schedule_dev(__device_attach_async_helper, 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);
 }
 
 /*
  * __device_driver_lock - acquire locks needed to manipulate dev->drv
  * @dev: Device we will update driver info for
  * @parent: Parent device. Needed if the bus requires parent lock
  *
  * This function will take the required locks for manipulating dev->drv.
  * Normally this will just be the @dev lock, but when called for a USB
  * interface, @parent lock will be held as well.
  */
 static void __device_driver_lock(struct device *dev, struct device *parent)
 {
     if (parent && dev->bus->need_parent_lock)
         device_lock(parent);
     device_lock(dev);
 }
 
 /*
  * __device_driver_unlock - release locks needed to manipulate dev->drv
  * @dev: Device we will update driver info for
  * @parent: Parent device. Needed if the bus requires parent lock
  *
  * This function will release the required locks for manipulating dev->drv.
  * Normally this will just be the @dev lock, but when called for a
  * USB interface, @parent lock will be released as well.
  */
 static void __device_driver_unlock(struct device *dev, struct device *parent)
 {
     device_unlock(dev);
     if (parent && dev->bus->need_parent_lock)
         device_unlock(parent);
 }
 
 /**
  * device_driver_attach - attach a specific driver to a specific device
  * @drv: Driver to attach
  * @dev: Device to attach it to
  *
  * Manually attach driver to a device. Will acquire both @dev lock and
  * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
  */
 int device_driver_attach(struct device_driver *drv, struct device *dev)
 {
     int ret;
 
     __device_driver_lock(dev, dev->parent);
     ret = __driver_probe_device(drv, dev);
     __device_driver_unlock(dev, dev->parent);
 
     /* also return probe errors as normal negative errnos */
     if (ret > 0)
         ret = -ret;
     if (ret == -EPROBE_DEFER)
         return -EAGAIN;
     return ret;
 }
 EXPORT_SYMBOL_GPL(device_driver_attach);
 
 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
 {
     struct device *dev = _dev;
     struct device_driver *drv;
     int ret;
 
     __device_driver_lock(dev, dev->parent);
     drv = dev->p->async_driver;
     dev->p->async_driver = NULL;
     ret = driver_probe_device(drv, dev);
     __device_driver_unlock(dev, dev->parent);
 
     dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
 
     put_device(dev);
 }
 
 static int __driver_attach(struct device *dev, void *data)
 {
     struct device_driver *drv = data;
     bool async = false;
     int ret;
 
     /*
      * 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.
      */
 
     ret = driver_match_device(drv, dev);
     if (ret == 0) {
         /* no match */
         return 0;
     } else if (ret == -EPROBE_DEFER) {
         dev_dbg(dev, "Device match requests probe deferral\n");
         dev->can_match = true;
         driver_deferred_probe_add(dev);
         /*
          * Driver could not match with device, but may match with
          * another device on the bus.
          */
         return 0;
     } else if (ret < 0) {
         dev_dbg(dev, "Bus failed to match device: %d\n", ret);
         return ret;
     } /* ret > 0 means positive match */
 
     if (driver_allows_async_probing(drv)) {
         /*
          * Instead of probing the device synchronously we will
          * probe it asynchronously to allow for more parallelism.
          *
          * We only take the device lock here in order to guarantee
          * that the dev->driver and async_driver fields are protected
          */
         dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
         device_lock(dev);
         if (!dev->driver && !dev->p->async_driver) {
             get_device(dev);
             dev->p->async_driver = drv;
             async = true;
         }
         device_unlock(dev);
         if (async)
             async_schedule_dev(__driver_attach_async_helper, dev);
         return 0;
     }
 
     __device_driver_lock(dev, dev->parent);
     driver_probe_device(drv, dev);
     __device_driver_unlock(dev, 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 *parent)
 {
     struct device_driver *drv;
 
     drv = dev->driver;
     if (drv) {
         pm_runtime_get_sync(dev);
 
         while (device_links_busy(dev)) {
             __device_driver_unlock(dev, parent);
 
             device_links_unbind_consumers(dev);
 
             __device_driver_lock(dev, parent);
             /*
              * A concurrent invocation of the same function might
              * have released the driver successfully while this one
              * was waiting, so check for that.
              */
             if (dev->driver != drv) {
                 pm_runtime_put(dev);
                 return;
             }
         }
 
         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);
 
         device_remove(dev);
 
         if (dev->bus && dev->bus->dma_cleanup)
             dev->bus->dma_cleanup(dev);
 
         device_links_driver_cleanup(dev);
         device_unbind_cleanup(dev);
 
         klist_remove(&dev->p->knode_driver);
         device_pm_check_callbacks(dev);
         if (dev->bus)
             blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                              BUS_NOTIFY_UNBOUND_DRIVER,
                              dev);
 
         kobject_uevent(&dev->kobj, KOBJ_UNBIND);
     }
 }
 
 void device_release_driver_internal(struct device *dev,
                     struct device_driver *drv,
                     struct device *parent)
 {
     __device_driver_lock(dev, parent);
 
     if (!drv || drv == dev->driver)
         __device_release_driver(dev, parent);
 
     __device_driver_unlock(dev, parent);
 }
 
 /**
  * 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.
  *
  * If this function is to be called with @dev->parent lock held, ensure that
  * the device's consumers are unbound in advance or that their locks can be
  * acquired under the @dev->parent lock.
  */
 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_release_driver_internal(dev, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(device_release_driver);
 
 /**
  * device_driver_detach - detach driver from a specific device
  * @dev: device to detach driver from
  *
  * Detach driver from device. Will acquire both @dev lock and @dev->parent
  * lock if needed.
  */
 void device_driver_detach(struct device *dev)
 {
     device_release_driver_internal(dev, NULL, dev->parent);
 }
 
 /**
  * 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;
 
     if (driver_allows_async_probing(drv))
         async_synchronize_full();
 
     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_last_entry(&drv->p->klist_devices.k_list,
                      struct device_private,
                      knode_driver.n_node);
         dev = dev_prv->device;
         get_device(dev);
         spin_unlock(&drv->p->klist_devices.k_lock);
         device_release_driver_internal(dev, drv, dev->parent);
         put_device(dev);
     }
 }

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