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linux/drivers/base/base.h
Alexander Duyck ef0ff68351 driver core: Probe devices asynchronously instead of the driver 
Probe devices asynchronously instead of the driver. This results in us
seeing the same behavior if the device is registered before the driver or
after. This way we can avoid serializing the initialization should the
driver not be loaded until after the devices have already been added.

The motivation behind this is that if we have a set of devices that
take a significant amount of time to load we can greatly reduce the time to
load by processing them in parallel instead of one at a time. In addition,
each device can exist on a different node so placing a single thread on one
CPU to initialize all of the devices for a given driver can result in poor
performance on a system with multiple nodes.

This approach can reduce the time needed to scan SCSI LUNs significantly.
The only way to realize that speedup is by enabling more concurrency which
is what is achieved with this patch.

To achieve this it was necessary to add a new member "async_driver" to the
device_private structure to store the driver pointer while we wait on the
deferred probe call.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-31 14:20:53 +01:00

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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/notifier.h>
/**
* struct subsys_private - structure to hold the private to the driver core portions of the bus_type/class structure.
*
* @subsys - the struct kset that defines this subsystem
* @devices_kset - the subsystem's 'devices' directory
* @interfaces - list of subsystem interfaces associated
* @mutex - protect the devices, and interfaces lists.
*
* @drivers_kset - the list of drivers associated
* @klist_devices - the klist to iterate over the @devices_kset
* @klist_drivers - the klist to iterate over the @drivers_kset
* @bus_notifier - the bus notifier list for anything that cares about things
* on this bus.
* @bus - pointer back to the struct bus_type that this structure is associated
* with.
*
* @glue_dirs - "glue" directory to put in-between the parent device to
* avoid namespace conflicts
* @class - pointer back to the struct class that this structure is associated
* with.
*
* This structure is the one that is the actual kobject allowing struct
* bus_type/class to be statically allocated safely. Nothing outside of the
* driver core should ever touch these fields.
*/
struct subsys_private {
struct kset subsys;
struct kset *devices_kset;
struct list_head interfaces;
struct mutex mutex;
struct kset *drivers_kset;
struct klist klist_devices;
struct klist klist_drivers;
struct blocking_notifier_head bus_notifier;
unsigned int drivers_autoprobe:1;
struct bus_type *bus;
struct kset glue_dirs;
struct class *class;
};
#define to_subsys_private(obj) container_of(obj, struct subsys_private, subsys.kobj)
struct driver_private {
struct kobject kobj;
struct klist klist_devices;
struct klist_node knode_bus;
struct module_kobject *mkobj;
struct device_driver *driver;
};
#define to_driver(obj) container_of(obj, struct driver_private, kobj)
/**
* struct device_private - structure to hold the private to the driver core portions of the device structure.
*
* @klist_children - klist containing all children of this device
* @knode_parent - node in sibling list
* @knode_driver - node in driver list
* @knode_bus - node in bus list
* @knode_class - node in class list
* @deferred_probe - entry in deferred_probe_list which is used to retry the
* binding of drivers which were unable to get all the resources needed by
* the device; typically because it depends on another driver getting
* probed first.
* @async_driver - pointer to device driver awaiting probe via async_probe
* @device - pointer back to the struct device that this structure is
* associated with.
* @dead - This device is currently either in the process of or has been
* removed from the system. Any asynchronous events scheduled for this
* device should exit without taking any action.
*
* Nothing outside of the driver core should ever touch these fields.
*/
struct device_private {
struct klist klist_children;
struct klist_node knode_parent;
struct klist_node knode_driver;
struct klist_node knode_bus;
struct klist_node knode_class;
struct list_head deferred_probe;
struct device_driver *async_driver;
struct device *device;
u8 dead:1;
};
#define to_device_private_parent(obj) \
container_of(obj, struct device_private, knode_parent)
#define to_device_private_driver(obj) \
container_of(obj, struct device_private, knode_driver)
#define to_device_private_bus(obj) \
container_of(obj, struct device_private, knode_bus)
#define to_device_private_class(obj) \
container_of(obj, struct device_private, knode_class)
/* initialisation functions */
extern int devices_init(void);
extern int buses_init(void);
extern int classes_init(void);
extern int firmware_init(void);
#ifdef CONFIG_SYS_HYPERVISOR
extern int hypervisor_init(void);
#else
static inline int hypervisor_init(void) { return 0; }
#endif
extern int platform_bus_init(void);
extern void cpu_dev_init(void);
extern void container_dev_init(void);
struct kobject *virtual_device_parent(struct device *dev);
extern int bus_add_device(struct device *dev);
extern void bus_probe_device(struct device *dev);
extern void bus_remove_device(struct device *dev);
extern int bus_add_driver(struct device_driver *drv);
extern void bus_remove_driver(struct device_driver *drv);
extern void device_release_driver_internal(struct device *dev,
struct device_driver *drv,
struct device *parent);
extern void driver_detach(struct device_driver *drv);
extern int driver_probe_device(struct device_driver *drv, struct device *dev);
extern void driver_deferred_probe_del(struct device *dev);
static inline int driver_match_device(struct device_driver *drv,
struct device *dev)
{
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);
extern void driver_remove_groups(struct device_driver *drv,
const struct attribute_group **groups);
int device_driver_attach(struct device_driver *drv, struct device *dev);
void device_driver_detach(struct device *dev);
extern char *make_class_name(const char *name, struct kobject *kobj);
extern int devres_release_all(struct device *dev);
extern void device_block_probing(void);
extern void device_unblock_probing(void);
/* /sys/devices directory */
extern struct kset *devices_kset;
extern void devices_kset_move_last(struct device *dev);
#if defined(CONFIG_MODULES) && defined(CONFIG_SYSFS)
extern void module_add_driver(struct module *mod, struct device_driver *drv);
extern void module_remove_driver(struct device_driver *drv);
#else
static inline void module_add_driver(struct module *mod,
struct device_driver *drv) { }
static inline void module_remove_driver(struct device_driver *drv) { }
#endif
#ifdef CONFIG_DEVTMPFS
extern int devtmpfs_init(void);
#else
static inline int devtmpfs_init(void) { return 0; }
#endif
/* Device links support */
extern int device_links_read_lock(void);
extern void device_links_read_unlock(int idx);
extern int device_links_check_suppliers(struct device *dev);
extern void device_links_driver_bound(struct device *dev);
extern void device_links_driver_cleanup(struct device *dev);
extern void device_links_no_driver(struct device *dev);
extern bool device_links_busy(struct device *dev);
extern void device_links_unbind_consumers(struct device *dev);
/* device pm support */
void device_pm_move_to_tail(struct device *dev);
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