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735a7ffb73
The multithreaded-probing code has a problem: after one initcall level (eg, core_initcall) has been processed, we will then start processing the next level (postcore_initcall) while the kernel threads which are handling core_initcall are still executing. This breaks the guarantees which the layered initcalls previously gave us. IOW, we want to be multithreaded _within_ an initcall level, but not between different levels. Fix that up by causing the probing code to wait for all outstanding probes at one level to complete before we start processing the next level. Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
376 lines
9.3 KiB
C
376 lines
9.3 KiB
C
/*
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* drivers/base/dd.c - The core device/driver interactions.
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*
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* This file contains the (sometimes tricky) code that controls the
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* interactions between devices and drivers, which primarily includes
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* driver binding and unbinding.
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*
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* All of this code used to exist in drivers/base/bus.c, but was
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* relocated to here in the name of compartmentalization (since it wasn't
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* strictly code just for the 'struct bus_type'.
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*
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* Copyright (c) 2002-5 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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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/wait.h>
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#include "base.h"
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#include "power/power.h"
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#define to_drv(node) container_of(node, struct device_driver, kobj.entry)
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/**
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* device_bind_driver - bind a driver to one device.
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* @dev: device.
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*
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* Allow manual attachment of a driver to a device.
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* Caller must have already set @dev->driver.
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*
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* Note that this does not modify the bus reference count
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* nor take the bus's rwsem. Please verify those are accounted
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* for before calling this. (It is ok to call with no other effort
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* from a driver's probe() method.)
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*
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* This function must be called with @dev->sem held.
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*/
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int device_bind_driver(struct device *dev)
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{
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int ret;
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if (klist_node_attached(&dev->knode_driver)) {
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printk(KERN_WARNING "%s: device %s already bound\n",
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__FUNCTION__, kobject_name(&dev->kobj));
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return 0;
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}
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pr_debug("bound device '%s' to driver '%s'\n",
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dev->bus_id, dev->driver->name);
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klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
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ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj,
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kobject_name(&dev->kobj));
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if (ret == 0) {
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ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
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"driver");
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if (ret)
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sysfs_remove_link(&dev->driver->kobj,
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kobject_name(&dev->kobj));
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}
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return ret;
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}
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struct stupid_thread_structure {
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struct device_driver *drv;
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struct device *dev;
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};
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static atomic_t probe_count = ATOMIC_INIT(0);
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static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
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static int really_probe(void *void_data)
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{
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struct stupid_thread_structure *data = void_data;
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struct device_driver *drv = data->drv;
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struct device *dev = data->dev;
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int ret = 0;
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atomic_inc(&probe_count);
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pr_debug("%s: Probing driver %s with device %s\n",
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drv->bus->name, drv->name, dev->bus_id);
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dev->driver = drv;
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if (dev->bus->probe) {
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ret = dev->bus->probe(dev);
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if (ret) {
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dev->driver = NULL;
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goto probe_failed;
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}
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} else if (drv->probe) {
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ret = drv->probe(dev);
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if (ret) {
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dev->driver = NULL;
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goto probe_failed;
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}
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}
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if (device_bind_driver(dev)) {
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printk(KERN_ERR "%s: device_bind_driver(%s) failed\n",
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__FUNCTION__, dev->bus_id);
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/* How does undo a ->probe? We're screwed. */
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}
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ret = 1;
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pr_debug("%s: Bound Device %s to Driver %s\n",
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drv->bus->name, dev->bus_id, drv->name);
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goto done;
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probe_failed:
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if (ret == -ENODEV || ret == -ENXIO) {
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/* Driver matched, but didn't support device
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* or device not found.
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* Not an error; keep going.
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*/
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ret = 0;
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} else {
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/* driver matched but the probe failed */
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printk(KERN_WARNING
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"%s: probe of %s failed with error %d\n",
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drv->name, dev->bus_id, ret);
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}
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done:
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kfree(data);
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atomic_dec(&probe_count);
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wake_up(&probe_waitqueue);
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return ret;
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}
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/**
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* driver_probe_done
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* Determine if the probe sequence is finished or not.
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*
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* Should somehow figure out how to use a semaphore, not an atomic variable...
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*/
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int driver_probe_done(void)
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{
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pr_debug("%s: probe_count = %d\n", __FUNCTION__,
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atomic_read(&probe_count));
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if (atomic_read(&probe_count))
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return -EBUSY;
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return 0;
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}
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/**
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* driver_probe_device - attempt to bind device & driver together
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* @drv: driver to bind a device to
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* @dev: device to try to bind to the driver
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*
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* First, we call the bus's match function, if one present, which should
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* compare the device IDs the driver supports with the device IDs of the
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* device. Note we don't do this ourselves because we don't know the
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* format of the ID structures, nor what is to be considered a match and
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* what is not.
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*
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* This function returns 1 if a match is found, an error if one occurs
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* (that is not -ENODEV or -ENXIO), and 0 otherwise.
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*
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* This function must be called with @dev->sem held. When called for a
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* USB interface, @dev->parent->sem must be held as well.
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*/
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int driver_probe_device(struct device_driver * drv, struct device * dev)
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{
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struct stupid_thread_structure *data;
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struct task_struct *probe_task;
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int ret = 0;
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if (!device_is_registered(dev))
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return -ENODEV;
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if (drv->bus->match && !drv->bus->match(dev, drv))
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goto done;
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pr_debug("%s: Matched Device %s with Driver %s\n",
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drv->bus->name, dev->bus_id, drv->name);
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data = kmalloc(sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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data->drv = drv;
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data->dev = dev;
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if (drv->multithread_probe) {
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probe_task = kthread_run(really_probe, data,
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"probe-%s", dev->bus_id);
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if (IS_ERR(probe_task))
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ret = really_probe(data);
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} else
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ret = really_probe(data);
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done:
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return ret;
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}
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static int __device_attach(struct device_driver * drv, void * data)
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{
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struct device * dev = data;
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return driver_probe_device(drv, dev);
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}
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/**
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* device_attach - try to attach device to a driver.
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* @dev: device.
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*
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* Walk the list of drivers that the bus has and call
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* driver_probe_device() for each pair. If a compatible
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* pair is found, break out and return.
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*
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* Returns 1 if the device was bound to a driver;
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* 0 if no matching device was found; error code otherwise.
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*
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* When called for a USB interface, @dev->parent->sem must be held.
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*/
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int device_attach(struct device * dev)
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{
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int ret = 0;
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down(&dev->sem);
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if (dev->driver) {
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ret = device_bind_driver(dev);
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if (ret == 0)
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ret = 1;
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} else
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ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
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up(&dev->sem);
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return ret;
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}
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static int __driver_attach(struct device * dev, void * data)
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{
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struct device_driver * drv = data;
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/*
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* Lock device and try to bind to it. We drop the error
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* here and always return 0, because we need to keep trying
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* to bind to devices and some drivers will return an error
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* simply if it didn't support the device.
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*
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* driver_probe_device() will spit a warning if there
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* is an error.
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*/
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if (dev->parent) /* Needed for USB */
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down(&dev->parent->sem);
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down(&dev->sem);
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if (!dev->driver)
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driver_probe_device(drv, dev);
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up(&dev->sem);
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if (dev->parent)
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up(&dev->parent->sem);
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return 0;
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}
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/**
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* driver_attach - try to bind driver to devices.
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* @drv: driver.
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*
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* Walk the list of devices that the bus has on it and try to
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* match the driver with each one. If driver_probe_device()
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* returns 0 and the @dev->driver is set, we've found a
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* compatible pair.
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*/
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int driver_attach(struct device_driver * drv)
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{
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return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
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}
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/**
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* device_release_driver - manually detach device from driver.
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* @dev: device.
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*
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* Manually detach device from driver.
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*
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* __device_release_driver() must be called with @dev->sem held.
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* When called for a USB interface, @dev->parent->sem must be held
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* as well.
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*/
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static void __device_release_driver(struct device * dev)
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{
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struct device_driver * drv;
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drv = dev->driver;
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if (drv) {
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get_driver(drv);
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sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
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sysfs_remove_link(&dev->kobj, "driver");
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klist_remove(&dev->knode_driver);
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if (dev->bus && dev->bus->remove)
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dev->bus->remove(dev);
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else if (drv->remove)
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drv->remove(dev);
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dev->driver = NULL;
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put_driver(drv);
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}
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}
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void device_release_driver(struct device * dev)
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{
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/*
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* If anyone calls device_release_driver() recursively from
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* within their ->remove callback for the same device, they
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* will deadlock right here.
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*/
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down(&dev->sem);
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__device_release_driver(dev);
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up(&dev->sem);
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}
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/**
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* driver_detach - detach driver from all devices it controls.
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* @drv: driver.
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*/
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void driver_detach(struct device_driver * drv)
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{
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struct device * dev;
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for (;;) {
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spin_lock(&drv->klist_devices.k_lock);
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if (list_empty(&drv->klist_devices.k_list)) {
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spin_unlock(&drv->klist_devices.k_lock);
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break;
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}
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dev = list_entry(drv->klist_devices.k_list.prev,
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struct device, knode_driver.n_node);
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get_device(dev);
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spin_unlock(&drv->klist_devices.k_lock);
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if (dev->parent) /* Needed for USB */
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down(&dev->parent->sem);
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down(&dev->sem);
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if (dev->driver == drv)
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__device_release_driver(dev);
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up(&dev->sem);
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if (dev->parent)
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up(&dev->parent->sem);
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put_device(dev);
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}
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}
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#ifdef CONFIG_PCI_MULTITHREAD_PROBE
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static int __init wait_for_probes(void)
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{
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DEFINE_WAIT(wait);
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printk(KERN_INFO "%s: waiting for %d threads\n", __FUNCTION__,
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atomic_read(&probe_count));
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if (!atomic_read(&probe_count))
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return 0;
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while (atomic_read(&probe_count)) {
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prepare_to_wait(&probe_waitqueue, &wait, TASK_UNINTERRUPTIBLE);
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if (atomic_read(&probe_count))
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schedule();
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}
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finish_wait(&probe_waitqueue, &wait);
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return 0;
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}
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core_initcall_sync(wait_for_probes);
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postcore_initcall_sync(wait_for_probes);
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arch_initcall_sync(wait_for_probes);
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subsys_initcall_sync(wait_for_probes);
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fs_initcall_sync(wait_for_probes);
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device_initcall_sync(wait_for_probes);
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late_initcall_sync(wait_for_probes);
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#endif
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EXPORT_SYMBOL_GPL(device_bind_driver);
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EXPORT_SYMBOL_GPL(device_release_driver);
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EXPORT_SYMBOL_GPL(device_attach);
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EXPORT_SYMBOL_GPL(driver_attach);
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