On Sunday 06 December 2009, Alan Stern wrote: > That's what other device controller drivers do. There's no choice. > (Except that I'm not sure they have individual locks for endpoints -- > just one single big spinlock.) Right; such fine grain locking tends to be more hassle than it's worth. ISTR studies from a while back showing locks need to be quite heavily contended before splitting them is worth much. Any per-controller lock for a UDC is unlikely to see much contention. > In fact, host controller drivers do the analogous thing. When they > give back completed URBs, they release their private spinlocks. For *exactly* the same reason. Upper level driver code shouldn't need to worry about whether it's re-entering some random bit of lower level code. As a rule, it can't know about that code. -- 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
