On Thu, 4 Jun 2009, Oliver Neukum wrote: > Am Mittwoch, 3. Juni 2009 18:37:38 schrieb Alan Stern: > > On Wed, 3 Jun 2009, Oliver Neukum wrote: > > > Hi Alan, > > > > > > I am looking at using the interface in practice. It seems to me that > > > pm_usage_cnt can become corrupted if usb_autopm_get_interface_async() > > > and usb_autopm_put_interface_async() race. Convert it to atomic_t? > > > > Or else have the driver do some sort of locking. You'd probably want > > locking anyway. > > The problem with that is that it is a difference in behavior to the sync > versions. It violates the principle of least surprise. We could convert the field to atomic_t; it wouldn't bother anyone. However it is worthwhile mentioning that this behavior of the async routines _is_ documented in Documentation/usb/power-management.txt. By the way, what is your application? And doesn't it turn out that you naturally want to hold a private lock during these calls anyway? Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
