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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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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_domain.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 256static 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(dev)) 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_dfl_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->deferred_probe_reason ?: "\n");
mutex_unlock(&deferred_probe_mutex);
return 0;}DEFINE_SHOW_ATTRIBUTE(deferred_devs);
static int driver_deferred_probe_timeout = CONFIG_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_warn(p->device, "deferred probe pending: %s", p->deferred_probe_reason ?: "(reason unknown)\n"); mutex_unlock(&deferred_probe_mutex);
fw_devlink_probing_done();}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 (delayed_work_pending(&deferred_probe_timeout_work) && mod_delayed_work(system_percpu_wq, &deferred_probe_timeout_work, secs_to_jiffies(driver_deferred_probe_timeout))) 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); }
if (!IS_ENABLED(CONFIG_MODULES)) fw_devlink_probing_done();
return 0;}late_initcall(deferred_probe_initcall);
static void __exit deferred_probe_exit(void){ debugfs_lookup_and_remove("devices_deferred", NULL);}__exitcall(deferred_probe_exit);
int __device_set_driver_override(struct device *dev, const char *s, size_t len){ const char *new = NULL, *old;
if (!s) return -EINVAL;
/* * The stored value will be used in sysfs show callback (sysfs_emit()), * which has a length limit of PAGE_SIZE and adds a trailing newline. * Thus we can store one character less to avoid truncation during sysfs * show. */ if (len >= (PAGE_SIZE - 1)) return -EINVAL;
/* * Compute the real length of the string in case userspace sends us a * bunch of \0 characters like python likes to do. */ len = strlen(s);
/* Handle trailing newline */ if (len) { char *cp;
cp = strnchr(s, len, '\n'); if (cp) len = cp - s; }
/* * If empty string or "\n" passed, new remains NULL, clearing * the driver_override.name. */ if (len) { new = kstrndup(s, len, GFP_KERNEL); if (!new) return -ENOMEM; }
scoped_guard(spinlock, &dev->driver_override.lock) { old = dev->driver_override.name; dev->driver_override.name = new; }
kfree(old);
return 0;}EXPORT_SYMBOL_GPL(__device_set_driver_override);
/** * 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);}EXPORT_SYMBOL_GPL(device_is_bound);
static void driver_bound(struct device *dev){ if (device_is_bound(dev)) { dev_warn(dev, "%s: device already bound\n", __func__); return; }
dev_dbg(dev, "driver: '%s': %s: bound to device\n", dev->driver->name, __func__);
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();
bus_notify(dev, BUS_NOTIFY_BOUND_DRIVER); 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;
bus_notify(dev, BUS_NOTIFY_BIND_DRIVER);
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 bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND); 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_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count){ int ret = 0;
if (strcmp("1", buf)) return -EINVAL;
device_lock(dev); if (!dev_test_and_set_state_synced(dev)) dev_sync_state(dev); else ret = -EINVAL; device_unlock(dev);
return ret ? ret : count;}
static ssize_t state_synced_show(struct device *dev, struct device_attribute *attr, char *buf){ bool val;
device_lock(dev); val = dev_state_synced(dev); device_unlock(dev);
return sysfs_emit(buf, "%u\n", val);}static DEVICE_ATTR_RW(state_synced);
static void device_unbind_cleanup(struct device *dev){ if (dev->driver->p_cb.post_unbind_rust) dev->driver->p_cb.post_unbind_rust(dev); devres_release_all(dev); arch_teardown_dma_ops(dev); kfree(dev->dma_range_map); dev->dma_range_map = NULL; device_set_driver(dev, NULL); dev_set_drvdata(dev, NULL); dev_pm_domain_detach(dev, dev->power.detach_power_off); 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, const 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: dev_dbg(dev, "probe with driver %s rejects match %d\n", drv->name, ret); break; default: /* driver matched but the probe failed */ dev_err(dev, "probe with driver %s failed with error %d\n", drv->name, ret); break; }
return ret;}
static int really_probe(struct device *dev, const 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;
dev_dbg(dev, "bus: '%s': %s: probing driver %s with device\n", drv->bus->name, __func__, drv->name); if (!list_empty(&dev->devres_head)) { dev_crit(dev, "Resources present before probing\n"); ret = -EBUSY; goto done; }
re_probe: device_set_driver(dev, 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) { dev_err(dev, "%s: driver_sysfs_add failed\n", __func__); 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); if (dev->bus && dev->bus->dma_cleanup) dev->bus->dma_cleanup(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); dev_dbg(dev, "bus: '%s': %s: bound device to driver %s\n", drv->bus->name, __func__, drv->name); goto done;
dev_sysfs_state_synced_failed:dev_groups_failed: device_remove(dev);probe_failed: driver_sysfs_remove(dev);sysfs_failed: bus_notify(dev, BUS_NOTIFY_DRIVER_NOT_BOUND); 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, const struct device_driver *drv){ ktime_t calltime, rettime; int ret;
calltime = ktime_get(); ret = really_probe(dev, drv); rettime = ktime_get(); /* * Don't change this to pr_debug() because that requires * CONFIG_DYNAMIC_DEBUG and we want a simple 'initcall_debug' on the * kernel commandline to print this all the time at the debug level. */ printk(KERN_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... */bool __init driver_probe_done(void){ int local_probe_count = atomic_read(&probe_count);
pr_debug("%s: probe_count = %d\n", __func__, local_probe_count); return !local_probe_count;}
/** * 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(const 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;
/* * In device_add(), the "struct device" gets linked into the subsystem's * list of devices and broadcast to userspace (via uevent) before we're * quite ready to probe. Those open pathways to driver probe before * we've finished enough of device_add() to reliably support probe. * Detect this and tell other pathways to try again later. device_add() * itself will also try to probe immediately after setting * "ready_to_probe". */ if (!dev_ready_to_probe(dev)) return dev_err_probe(dev, -EPROBE_DEFER, "Device not ready to probe\n");
/* * Call dev_set_can_match() after calling dev_ready_to_probe(), so * driver_deferred_probe_add() won't actually add the device to the * deferred probe list when dev_ready_to_probe() returns false. * * When dev_ready_to_probe() returns false, it means that device_add() * will do another probe() attempt for us. */ dev_set_can_match(dev); dev_dbg(dev, "bus: '%s': %s: matched device with driver %s\n", drv->bus->name, __func__, 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(const 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");
strscpy(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);
static bool driver_allows_async_probing(const 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_set_can_match(dev); 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 { device_set_driver(dev, 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){ struct subsys_private *sp = bus_to_subsys(dev->bus);
if (!sp) return;
if (sp->drivers_autoprobe) __device_attach(dev, true);
subsys_put(sp);}
/* * __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(const 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; const 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){ const 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_set_can_match(dev); 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); /* * Driver could not match with device, but may match with * another device on the bus. */ return 0; } /* 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(const struct device_driver *drv){ /* The (void *) will be put back to const * in __driver_attach() */ return bus_for_each_dev(drv->bus, NULL, (void *)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);
bus_notify(dev, BUS_NOTIFY_UNBIND_DRIVER);
pm_runtime_put_sync(dev);
device_remove(dev);
if (dev->bus && dev->bus->dma_cleanup) dev->bus->dma_cleanup(dev);
device_unbind_cleanup(dev); device_links_driver_cleanup(dev);
klist_remove(&dev->p->knode_driver); device_pm_check_callbacks(dev);
bus_notify(dev, BUS_NOTIFY_UNBOUND_DRIVER); kobject_uevent(&dev->kobj, KOBJ_UNBIND); }}
void device_release_driver_internal(struct device *dev, const 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(const 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); }}