*
*/
+#include <linux/async.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/errno.h>
{
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)
}
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.
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);
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;
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;
drv = dev->driver;
if (drv) {
+ if (driver_allows_async_probing(drv))
+ async_synchronize_full();
+
pm_runtime_get_sync(dev);
driver_sysfs_remove(dev);
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.
* @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,
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;
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);
/*
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff