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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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81107bf531
This patch (as783) simplifies the driver core slightly by removing four unnecessary _get and _put methods. It is vital that when a driver is removed from its bus's klist of registered drivers, or when a device is removed from a driver's klist of bound devices, that the klist updates complete synchronously. Otherwise the kernel might try binding an unregistered driver to a newly-registered device, or adding a device to the klist for a new driver before it has been removed from the old driver's klist. Since the removals must be synchronous, they don't need to update any reference counts. Hence the _get and _put methods can be dispensed with. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
215 lines
5.4 KiB
C
215 lines
5.4 KiB
C
/*
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* driver.c - centralized device driver management
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*
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* Copyright (c) 2002-3 Patrick Mochel
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* Copyright (c) 2002-3 Open Source Development Labs
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*
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* This file is released under the GPLv2
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*
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*/
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include "base.h"
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#define to_dev(node) container_of(node, struct device, driver_list)
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#define to_drv(obj) container_of(obj, struct device_driver, kobj)
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static struct device * next_device(struct klist_iter * i)
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{
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struct klist_node * n = klist_next(i);
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return n ? container_of(n, struct device, knode_driver) : NULL;
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}
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/**
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* driver_for_each_device - Iterator for devices bound to a driver.
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* @drv: Driver we're iterating.
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* @start: Device to begin with
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* @data: Data to pass to the callback.
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* @fn: Function to call for each device.
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*
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* Iterate over the @drv's list of devices calling @fn for each one.
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*/
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int driver_for_each_device(struct device_driver * drv, struct device * start,
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void * data, int (*fn)(struct device *, void *))
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{
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struct klist_iter i;
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struct device * dev;
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int error = 0;
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if (!drv)
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return -EINVAL;
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klist_iter_init_node(&drv->klist_devices, &i,
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start ? &start->knode_driver : NULL);
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while ((dev = next_device(&i)) && !error)
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error = fn(dev, data);
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klist_iter_exit(&i);
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return error;
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}
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EXPORT_SYMBOL_GPL(driver_for_each_device);
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/**
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* driver_find_device - device iterator for locating a particular device.
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* @drv: The device's driver
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* @start: Device to begin with
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* @data: Data to pass to match function
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* @match: Callback function to check device
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*
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* This is similar to the driver_for_each_device() function above, but
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* it returns a reference to a device that is 'found' for later use, as
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* determined by the @match callback.
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*
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* The callback should return 0 if the device doesn't match and non-zero
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* if it does. If the callback returns non-zero, this function will
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* return to the caller and not iterate over any more devices.
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*/
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struct device * driver_find_device(struct device_driver *drv,
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struct device * start, void * data,
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int (*match)(struct device *, void *))
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{
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struct klist_iter i;
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struct device *dev;
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if (!drv)
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return NULL;
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klist_iter_init_node(&drv->klist_devices, &i,
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(start ? &start->knode_driver : NULL));
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while ((dev = next_device(&i)))
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if (match(dev, data) && get_device(dev))
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break;
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klist_iter_exit(&i);
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return dev;
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}
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EXPORT_SYMBOL_GPL(driver_find_device);
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/**
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* driver_create_file - create sysfs file for driver.
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* @drv: driver.
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* @attr: driver attribute descriptor.
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*/
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int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
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{
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int error;
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if (get_driver(drv)) {
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error = sysfs_create_file(&drv->kobj, &attr->attr);
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put_driver(drv);
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} else
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error = -EINVAL;
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return error;
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}
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/**
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* driver_remove_file - remove sysfs file for driver.
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* @drv: driver.
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* @attr: driver attribute descriptor.
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*/
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void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
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{
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if (get_driver(drv)) {
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sysfs_remove_file(&drv->kobj, &attr->attr);
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put_driver(drv);
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}
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}
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/**
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* get_driver - increment driver reference count.
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* @drv: driver.
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*/
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struct device_driver * get_driver(struct device_driver * drv)
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{
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return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
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}
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/**
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* put_driver - decrement driver's refcount.
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* @drv: driver.
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*/
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void put_driver(struct device_driver * drv)
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{
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kobject_put(&drv->kobj);
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}
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/**
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* driver_register - register driver with bus
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* @drv: driver to register
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*
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* We pass off most of the work to the bus_add_driver() call,
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* since most of the things we have to do deal with the bus
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* structures.
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*
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* The one interesting aspect is that we setup @drv->unloaded
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* as a completion that gets complete when the driver reference
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* count reaches 0.
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*/
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int driver_register(struct device_driver * drv)
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{
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if ((drv->bus->probe && drv->probe) ||
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(drv->bus->remove && drv->remove) ||
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(drv->bus->shutdown && drv->shutdown)) {
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printk(KERN_WARNING "Driver '%s' needs updating - please use bus_type methods\n", drv->name);
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}
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klist_init(&drv->klist_devices, NULL, NULL);
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init_completion(&drv->unloaded);
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return bus_add_driver(drv);
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}
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/**
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* driver_unregister - remove driver from system.
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* @drv: driver.
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*
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* Again, we pass off most of the work to the bus-level call.
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*
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* Though, once that is done, we wait until @drv->unloaded is completed.
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* This will block until the driver refcount reaches 0, and it is
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* released. Only modular drivers will call this function, and we
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* have to guarantee that it won't complete, letting the driver
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* unload until all references are gone.
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*/
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void driver_unregister(struct device_driver * drv)
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{
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bus_remove_driver(drv);
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wait_for_completion(&drv->unloaded);
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}
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/**
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* driver_find - locate driver on a bus by its name.
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* @name: name of the driver.
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* @bus: bus to scan for the driver.
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*
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* Call kset_find_obj() to iterate over list of drivers on
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* a bus to find driver by name. Return driver if found.
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*
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* Note that kset_find_obj increments driver's reference count.
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*/
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struct device_driver *driver_find(const char *name, struct bus_type *bus)
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{
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struct kobject *k = kset_find_obj(&bus->drivers, name);
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if (k)
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return to_drv(k);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(driver_register);
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EXPORT_SYMBOL_GPL(driver_unregister);
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EXPORT_SYMBOL_GPL(get_driver);
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EXPORT_SYMBOL_GPL(put_driver);
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EXPORT_SYMBOL_GPL(driver_find);
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EXPORT_SYMBOL_GPL(driver_create_file);
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EXPORT_SYMBOL_GPL(driver_remove_file);
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