Greg:
This is a revised version (as641b) of the earlier patch that James
Bottomley didn't like. It goes in the direction of eliminating
klist_remove entirely. (One more patch is still needed...)
Add an is_registered flag to struct device, so that drivers
won't get bound to a device after it is gone.
When unregistering a driver, use the drv->unloaded completion
to wait for the device_driver structure to be removed from
the bus's klist instead of using klist_remove. This also
eliminates the need for the klist_drivers_get method. (It's
not a violation of the refcounting credo, because we have to
wait in any case for the driver to be completely idle before
driver_unregister can return.)
Likewise, the klist_devices_get and klist_devices_put methods
in drivers.c aren't needed, because we always have to wait for
a device to be completely removed from its driver's klist. In
fact, this is the last remaining usage of klist_remove.
Move the call to a klist's put method outside the scope of the
spinlock (i.e., move it from klist_release to klist_del and
klist_next).
The one unpalatable aspect of this patch is that it adds a new single-bit
flag to struct device, thereby increasing the structure's size by at least
4 bytes.
Alan Stern
Signed-off-by: Alan Stern <[email protected]>
---
Index: usb-2.6/drivers/base/dd.c
===================================================================
--- usb-2.6.orig/drivers/base/dd.c
+++ usb-2.6/drivers/base/dd.c
@@ -72,6 +72,8 @@ int driver_probe_device(struct device_dr
{
int ret = 0;
+ if (!device_is_registered(dev))
+ return -ENODEV;
if (drv->bus->match && !drv->bus->match(dev, drv))
goto Done;
Index: usb-2.6/drivers/base/bus.c
===================================================================
--- usb-2.6.orig/drivers/base/bus.c
+++ usb-2.6/drivers/base/bus.c
@@ -367,6 +367,7 @@ int bus_add_device(struct device * dev)
if (bus) {
pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
+ dev->is_registered = 1;
device_attach(dev);
klist_add_tail(&dev->knode_bus, &bus->klist_devices);
error = device_add_attrs(bus, dev);
@@ -393,7 +394,8 @@ void bus_remove_device(struct device * d
sysfs_remove_link(&dev->kobj, "bus");
sysfs_remove_link(&dev->bus->devices.kobj, dev->bus_id);
device_remove_attrs(dev->bus, dev);
- klist_remove(&dev->knode_bus);
+ klist_del(&dev->knode_bus);
+ dev->is_registered = 0;
pr_debug("bus %s: remove device %s\n", dev->bus->name, dev->bus_id);
device_release_driver(dev);
put_bus(dev->bus);
@@ -500,7 +502,8 @@ void bus_remove_driver(struct device_dri
if (drv->bus) {
remove_bind_files(drv);
driver_remove_attrs(drv->bus, drv);
- klist_remove(&drv->knode_bus);
+ klist_del(&drv->knode_bus);
+ wait_for_completion(&drv->unloaded);
pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);
driver_detach(drv);
module_remove_driver(drv);
@@ -613,20 +616,12 @@ static void klist_devices_put(struct kli
put_device(dev);
}
-static void klist_drivers_get(struct klist_node *n)
-{
- struct device_driver *drv = container_of(n, struct device_driver,
- knode_bus);
-
- get_driver(drv);
-}
-
static void klist_drivers_put(struct klist_node *n)
{
struct device_driver *drv = container_of(n, struct device_driver,
knode_bus);
- put_driver(drv);
+ complete(&drv->unloaded);
}
/**
@@ -664,7 +659,7 @@ int bus_register(struct bus_type * bus)
goto bus_drivers_fail;
klist_init(&bus->klist_devices, klist_devices_get, klist_devices_put);
- klist_init(&bus->klist_drivers, klist_drivers_get, klist_drivers_put);
+ klist_init(&bus->klist_drivers, NULL, klist_drivers_put);
bus_add_attrs(bus);
pr_debug("bus type '%s' registered\n", bus->name);
Index: usb-2.6/drivers/base/driver.c
===================================================================
--- usb-2.6.orig/drivers/base/driver.c
+++ usb-2.6/drivers/base/driver.c
@@ -143,20 +143,6 @@ void put_driver(struct device_driver * d
kobject_put(&drv->kobj);
}
-static void klist_devices_get(struct klist_node *n)
-{
- struct device *dev = container_of(n, struct device, knode_driver);
-
- get_device(dev);
-}
-
-static void klist_devices_put(struct klist_node *n)
-{
- struct device *dev = container_of(n, struct device, knode_driver);
-
- put_device(dev);
-}
-
/**
* driver_register - register driver with bus
* @drv: driver to register
@@ -176,7 +162,7 @@ int driver_register(struct device_driver
(drv->bus->shutdown && drv->shutdown)) {
printk(KERN_WARNING "Driver '%s' needs updating - please use bus_type methods\n", drv->name);
}
- klist_init(&drv->klist_devices, klist_devices_get, klist_devices_put);
+ klist_init(&drv->klist_devices, NULL, NULL);
init_completion(&drv->unloaded);
return bus_add_driver(drv);
}
Index: usb-2.6/lib/klist.c
===================================================================
--- usb-2.6.orig/lib/klist.c
+++ usb-2.6/lib/klist.c
@@ -123,12 +123,10 @@ EXPORT_SYMBOL_GPL(klist_add_tail);
static void klist_release(struct kref * kref)
{
struct klist_node * n = container_of(kref, struct klist_node, n_ref);
- void (*put)(struct klist_node *) = n->n_klist->put;
+
list_del(&n->n_node);
complete(&n->n_removed);
n->n_klist = NULL;
- if (put)
- put(n);
}
static int klist_dec_and_del(struct klist_node * n)
@@ -145,10 +143,14 @@ static int klist_dec_and_del(struct klis
void klist_del(struct klist_node * n)
{
struct klist * k = n->n_klist;
+ void (*put)(struct klist_node *) = k->put;
spin_lock(&k->k_lock);
- klist_dec_and_del(n);
+ if (!klist_dec_and_del(n))
+ put = NULL;
spin_unlock(&k->k_lock);
+ if (put)
+ put(n);
}
EXPORT_SYMBOL_GPL(klist_del);
@@ -161,10 +163,7 @@ EXPORT_SYMBOL_GPL(klist_del);
void klist_remove(struct klist_node * n)
{
- struct klist * k = n->n_klist;
- spin_lock(&k->k_lock);
- klist_dec_and_del(n);
- spin_unlock(&k->k_lock);
+ klist_del(n);
wait_for_completion(&n->n_removed);
}
@@ -260,12 +259,15 @@ static struct klist_node * to_klist_node
struct klist_node * klist_next(struct klist_iter * i)
{
struct list_head * next;
+ struct klist_node * lnode = i->i_cur;
struct klist_node * knode = NULL;
+ void (*put)(struct klist_node *) = i->i_klist->put;
spin_lock(&i->i_klist->k_lock);
- if (i->i_cur) {
- next = i->i_cur->n_node.next;
- klist_dec_and_del(i->i_cur);
+ if (lnode) {
+ next = lnode->n_node.next;
+ if (!klist_dec_and_del(lnode))
+ put = NULL;
} else
next = i->i_head->next;
@@ -275,6 +277,8 @@ struct klist_node * klist_next(struct kl
}
i->i_cur = knode;
spin_unlock(&i->i_klist->k_lock);
+ if (put && lnode)
+ put(lnode);
return knode;
}
Index: usb-2.6/include/linux/device.h
===================================================================
--- usb-2.6.orig/include/linux/device.h
+++ usb-2.6/include/linux/device.h
@@ -311,6 +311,7 @@ struct device {
struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */
+ u8 is_registered;
struct device_attribute uevent_attr;
struct semaphore sem; /* semaphore to synchronize calls to
@@ -356,7 +357,7 @@ dev_set_drvdata (struct device *dev, voi
static inline int device_is_registered(struct device *dev)
{
- return klist_node_attached(&dev->knode_bus);
+ return dev->is_registered;
}
/*
-
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