diff options
| -rw-r--r-- | drivers/base/base.h | 1 | ||||
| -rw-r--r-- | drivers/base/bus.c | 31 | ||||
| -rw-r--r-- | drivers/base/dd.c | 149 | ||||
| -rw-r--r-- | include/linux/device.h | 28 |
4 files changed, 182 insertions, 27 deletions
diff --git a/drivers/base/base.h b/drivers/base/base.h index 251c5d30f963..fd3347d9f153 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -116,6 +116,7 @@ static inline int driver_match_device(struct device_driver *drv, { return drv->bus->match ? drv->bus->match(dev, drv) : 1; } +extern bool driver_allows_async_probing(struct device_driver *drv); extern int driver_add_groups(struct device_driver *drv, const struct attribute_group **groups); diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 79bc203f51ef..500592486e88 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -10,6 +10,7 @@ * */ +#include <linux/async.h> #include <linux/device.h> #include <linux/module.h> #include <linux/errno.h> @@ -549,15 +550,12 @@ void bus_probe_device(struct device *dev) { struct bus_type *bus = dev->bus; struct subsys_interface *sif; - int ret; if (!bus) return; - if (bus->p->drivers_autoprobe) { - ret = device_attach(dev); - WARN_ON(ret < 0); - } + if (bus->p->drivers_autoprobe) + device_initial_probe(dev); mutex_lock(&bus->p->mutex); list_for_each_entry(sif, &bus->p->interfaces, node) @@ -659,6 +657,17 @@ static ssize_t uevent_store(struct device_driver *drv, const char *buf, } static DRIVER_ATTR_WO(uevent); +static void driver_attach_async(void *_drv, async_cookie_t cookie) +{ + struct device_driver *drv = _drv; + int ret; + + ret = driver_attach(drv); + + pr_debug("bus: '%s': driver %s async attach completed: %d\n", + drv->bus->name, drv->name, ret); +} + /** * bus_add_driver - Add a driver to the bus. * @drv: driver. @@ -691,9 +700,15 @@ int bus_add_driver(struct device_driver *drv) klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers); if (drv->bus->p->drivers_autoprobe) { - error = driver_attach(drv); - if (error) - goto out_unregister; + if (driver_allows_async_probing(drv)) { + pr_debug("bus: '%s': probing driver %s asynchronously\n", + drv->bus->name, drv->name); + async_schedule(driver_attach_async, drv); + } else { + error = driver_attach(drv); + if (error) + goto out_unregister; + } } module_add_driver(drv->owner, drv); diff --git a/drivers/base/dd.c b/drivers/base/dd.c index e843fdbe4925..2ad33b21888c 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -417,31 +417,95 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) return ret; } -static int __device_attach(struct device_driver *drv, void *data) +bool driver_allows_async_probing(struct device_driver *drv) { - struct device *dev = data; + return drv->probe_type == PROBE_PREFER_ASYNCHRONOUS; +} + +struct device_attach_data { + struct device *dev; + + /* + * Indicates whether we are 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; + + /* + * 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); } -/** - * 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) +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); + + bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver); + dev_dbg(dev, "async probe completed\n"); + + pm_request_idle(dev); + + device_unlock(dev); + + put_device(dev); +} + +int __device_attach(struct device *dev, bool allow_async) { int ret = 0; @@ -459,15 +523,59 @@ int device_attach(struct device *dev) ret = 0; } } else { - ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); - pm_request_idle(dev); + struct device_attach_data data = { + .dev = dev, + .check_async = allow_async, + .want_async = false, + }; + + 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); + } } 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; @@ -522,6 +630,9 @@ static void __device_release_driver(struct device *dev) drv = dev->driver; if (drv) { + if (driver_allows_async_probing(drv)) + async_synchronize_full(); + pm_runtime_get_sync(dev); driver_sysfs_remove(dev); diff --git a/include/linux/device.h b/include/linux/device.h index 6558af90c8fe..7857b46c548b 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -196,12 +196,38 @@ extern struct kset *bus_get_kset(struct bus_type *bus); extern struct klist *bus_get_device_klist(struct bus_type *bus); /** + * enum probe_type - device driver probe type to try + * Device drivers may opt in for special handling of their + * respective probe routines. This tells the core what to + * expect and prefer. + * + * @PROBE_SYNCHRONOUS: Default. Drivers expect their probe routines + * to run synchronously with driver and device registration + * (with the exception of -EPROBE_DEFER handling - re-probing + * always ends up being done asynchronously). + * @PROBE_PREFER_ASYNCHRONOUS: Drivers for "slow" devices which + * probing order is not essential for booting the system may + * opt into executing their probes asynchronously. + * + * Note that the end goal is to switch the kernel to use asynchronous + * probing by default, so annotating drivers with + * %PROBE_PREFER_ASYNCHRONOUS is a temporary measure that allows us + * to speed up boot process while we are validating the rest of the + * drivers. + */ +enum probe_type { + PROBE_SYNCHRONOUS, + PROBE_PREFER_ASYNCHRONOUS, +}; + +/** * struct device_driver - The basic device driver structure * @name: Name of the device driver. * @bus: The bus which the device of this driver belongs to. * @owner: The module owner. * @mod_name: Used for built-in modules. * @suppress_bind_attrs: Disables bind/unbind via sysfs. + * @probe_type: Type of the probe (synchronous or asynchronous) to use. * @of_match_table: The open firmware table. * @acpi_match_table: The ACPI match table. * @probe: Called to query the existence of a specific device, @@ -235,6 +261,7 @@ struct device_driver { const char *mod_name; /* used for built-in modules */ bool suppress_bind_attrs; /* disables bind/unbind via sysfs */ + enum probe_type probe_type; const struct of_device_id *of_match_table; const struct acpi_device_id *acpi_match_table; @@ -975,6 +1002,7 @@ extern int __must_check device_bind_driver(struct device *dev); extern void device_release_driver(struct device *dev); extern int __must_check device_attach(struct device *dev); extern int __must_check driver_attach(struct device_driver *drv); +extern void device_initial_probe(struct device *dev); extern int __must_check device_reprobe(struct device *dev); /* |