Hi. Sorry about the long delay in replying, I've been out of town, and am
actually about to leave again for a week+ in a few hours...
> So the __MOD_{INC,DEC}_USE_COUNT() should oops right here.
> If you tested it and it doesn't oops, I don't understand why.
>
> So, for one, if you want to go that road, you should use fops_get()/put()
> (you can use just these, or rename them appropriately), they'll do the
> right thing if a thing is modular as opposed to built-in (owner == NULL).
Ah yes; patch appended which does just that.
> And, you need to set the owner from the module which you want to protect.
>
> So in the your driver:
>
> struct pci_driver my_drv {
> probe: ...
> driver : {
> owner: THIS_MODULE,
> }
> }
This is certainly not the prettiest, and I've run into it when setting
other generic driver fields. Is there a cleaner way to do this?
> which certainly is ugly since owner is in a sub-struct. But it's not
> really a possibility anyway, since in this case pci_register_driver will
> do a MOD_INC_USE_COUNT and you never have a chance to call
> pci_unregister_driver() to decrement it again, since you need to have it
> decremented before you can call pci_unregister_driver() (because
> that's called from your module_exit() function).
pci_register_driver() doesn't inc the refcount. The refcount is held at 1
by the module loading code, IIUC, until module_init() is done. After that,
the refcount stays at 0 until someone uses it.
-pat
===== drivers/base/driver.c 1.7 vs edited =====
--- 1.7/drivers/base/driver.c Wed Jun 5 15:59:31 2002
+++ edited/drivers/base/driver.c Mon Jun 10 06:54:00 2002
@@ -67,54 +67,55 @@
pr_debug("Registering driver '%s' with bus '%s'\n",drv->name,drv->bus->name);
get_bus(drv->bus);
- atomic_set(&drv->refcount,2);
rwlock_init(&drv->lock);
INIT_LIST_HEAD(&drv->devices);
+ SET_MODULE_OWNER(drv);
write_lock(&drv->bus->lock);
list_add(&drv->bus_list,&drv->bus->drivers);
write_unlock(&drv->bus->lock);
driver_make_dir(drv);
driver_attach(drv);
- put_driver(drv);
return 0;
}
-static void __remove_driver(struct device_driver * drv)
+void driver_unregister(struct device_driver * drv)
{
- pr_debug("Unregistering driver '%s' from bus '%s'\n",drv->name,drv->bus->name);
+ struct bus_type * bus;
+
+ write_lock(&drv->lock);
+ bus = drv->bus;
+ drv->bus = NULL;
+ write_unlock(&drv->lock);
+
+ /* make sure no one can get to it via the bus any more */
+ write_lock(&bus->lock);
+ list_del_init(&drv->bus_list);
+ write_unlock(&bus->lock);
+
+ /* force removal from devices */
driver_detach(drv);
+
+ pr_debug("Unregistering driver '%s' from bus '%s'\n",drv->name,drv->bus->name);
driverfs_remove_dir(&drv->dir);
- if (drv->release)
- drv->release(drv);
- put_bus(drv->bus);
+
+ put_bus(bus);
}
-void remove_driver(struct device_driver * drv)
+struct device_driver * get_driver(struct device_driver * drv)
{
- write_lock(&drv->bus->lock);
- atomic_set(&drv->refcount,0);
- list_del_init(&drv->bus_list);
- write_unlock(&drv->bus->lock);
- __remove_driver(drv);
+ if (drv && drv->owner)
+ if (!try_inc_mod_count(drv->owner))
+ return NULL;
+ return drv;
}
-/**
- * put_driver - decrement driver's refcount and clean up if necessary
- * @drv: driver in question
- */
void put_driver(struct device_driver * drv)
{
- write_lock(&drv->bus->lock);
- if (!atomic_dec_and_test(&drv->refcount)) {
- write_unlock(&drv->bus->lock);
- return;
- }
- list_del_init(&drv->bus_list);
- write_unlock(&drv->bus->lock);
- __remove_driver(drv);
+ if (drv && drv->owner)
+ __MOD_DEC_USE_COUNT(drv->owner);
}
EXPORT_SYMBOL(driver_for_each_dev);
EXPORT_SYMBOL(driver_register);
+EXPORT_SYMBOL(driver_unregister);
EXPORT_SYMBOL(put_driver);
-EXPORT_SYMBOL(remove_driver);
===== include/linux/device.h 1.20 vs edited =====
--- 1.20/include/linux/device.h Wed Jun 5 14:43:23 2002
+++ edited/include/linux/device.h Thu Jun 6 16:13:19 2002
@@ -90,7 +90,7 @@
struct bus_type * bus;
rwlock_t lock;
- atomic_t refcount;
+ struct module * owner;
list_t bus_list;
list_t devices;
@@ -102,23 +102,15 @@
int (*suspend) (struct device * dev, u32 state, u32 level);
int (*resume) (struct device * dev, u32 level);
-
- void (*release) (struct device_driver * drv);
};
extern int driver_register(struct device_driver * drv);
+extern void driver_unregister(struct device_driver * drv);
-static inline struct device_driver * get_driver(struct device_driver * drv)
-{
- BUG_ON(!atomic_read(&drv->refcount));
- atomic_inc(&drv->refcount);
- return drv;
-}
-
+extern struct device_driver * get_driver(struct device_driver * drv);
extern void put_driver(struct device_driver * drv);
-extern void remove_driver(struct device_driver * drv);
extern int driver_for_each_dev(struct device_driver * drv, void * data,
int (*callback)(struct device * dev, void * data));
-
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This archive was generated by hypermail 2b29 : Sat Jun 15 2002 - 22:00:18 EST