On Wednesday 11 April 2001 23:10, you wrote:
> We use reference counting for most of the structures we use. The ioctl
> (or usbdevfs) should increment the reference count on the device when
> the application open's the device.
> When usb_disconnect gets called, it'll decrement the reference count and
> won't free the memory for the structure.
In the standard kernel only three drivers use the reference counts, according
to a grep usb_inc_dev_use, and they increase the refcount in probe() and
decrement it in disconnect(). Is there any guarantee that there are no
running file_operations during disconnect()? Otherwise the refcount doesnt
help. Incrementing the refcount in the ioctl handler isn't much better, the
usb_device struct could have been freed in the time between the ioctl start
and the refcount incrementation. Using refcounts only lowers the probability
of a failure.
bye...
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