On Sun, 1 Apr 2007, Pavel Machek wrote:
>
> > @@ -183,7 +183,8 @@ int driver_register(struct device_driver
> > void driver_unregister(struct device_driver * drv)
> > {
> > bus_remove_driver(drv);
> > - wait_for_completion(&drv->unloaded);
> > + if (!drv->unloaded.done)
> > + WARN_ON(1);
> > }
>
> WARN_ON(!done)?
I think the whole "wait_for_completion()" is just broken.
We asked to *unregister* the driver, not to wait for users.
I would suggest that for 2.6.21, the minimal fix is actually something
like the appended. Comments? Ingo, does this fix things for you?
In general, I think the whole "wait for locks" or "wait for users" is
almost always a sign of a much bigger bug in reference counting. Modules
are special, though, since module code/data doesn't really get reference
counted. But doing it for built-in stuff when you don't need to really
just sounds *wrong*.
Linus
---
drivers/base/driver.c | 9 ++++++++-
1 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 1214cbd..082bfde 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -183,7 +183,14 @@ int driver_register(struct device_driver * drv)
void driver_unregister(struct device_driver * drv)
{
bus_remove_driver(drv);
- wait_for_completion(&drv->unloaded);
+ /*
+ * If the driver is a module, we are probably in
+ * the module unload path, and we want to wait
+ * for everything to unload before we can actually
+ * finish the unload.
+ */
+ if (drv->owner)
+ wait_for_completion(&drv->unloaded);
}
/**
-
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