On Tue, 2006-03-14 at 09:05 -0800, Greg KH wrote: > Ah, wait, that's the issue right there. You need to increment the > reference count of the object on open and then decrement it on close. > That way the last close will drop the last reference, and you do that > _after_ the tty cleanup.
acm_probe() gets a reference to acm->control->dev just before calling tty_register_device(), and it holds that reference until just after calling tty_unregister_device(). sysfs also takes a reference to acm->control->dev as the target of a symlink So there should be at least two references pinning acm->control->dev on entry to tty_unregister_device. The printk patch I asked Bob to try should tell us the actual reference counts. Maybe the counts get out of wack someplace else. Adding extra reference on tty open may work, but may just cover an existing reference count problem. The two calls resulting from tty_unregister_device(): sysfs_remove_link(&class_dev->kobj, "device"); sysfs_remove_link(&class_dev->dev->kobj, class_name); The first call removes the link where acm->control->dev is the target, which drops one reference. The second call directly accesses acm->control->dev. So if the reference count gets off by even one, the second call could oops. That's my best understanding of it at this point, but I've been wrong on my last couple of assertions. It may be worth waiting for Bob to report the actual ref counts before adding another ref on tty open. -- Paul Fulghum Microgate Systems, Ltd ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
