Some information that may be helpful: There's a significant difference in the way a signal handler is used versus the way signalfd notifications are used. That difference is that the signal is unblocked when a signal handler is used (so that the handler can catch it) but is blocked when signalfd notifications are used (so that a handler won't catch it). This difference offers a possible explanation. Is it possible that usbfs sets up the signal right away, but blocks it until the URB completes? If so, the signal would remain pending and a signal handler would get it at the right time whereas a signalfd notification would occur immediately. -- Dave Mielke | 2213 Fox Crescent | The Bible is the very Word of God. Phone: 1-613-726-0014 | Ottawa, Ontario | http://Mielke.cc/bible/ EMail: dave@xxxxxxxxx | Canada K2A 1H7 | http://FamilyRadio.com/ -- 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