> >> Should use client->head here so that the SYN_DROPPED is readable. > > > > It is readable, but we do not want to signal on it. > > I think we do want to signal on it. We should signal whenever the > device becomes readable. > > Signaling on dropped is useful in the case where a misbehaving device > driver fails to ever call input_sync. If that happens, we might > enqueue a dropped event and then never wake up the client which makes > the issue hard to diagnose. A device that never wakes up the client seems like a detectable symptom. I agree with Dmitry, the dropped event is more of a note in passing, and as such can stay in the pipe until a real EV_SYN event comes along. > >> I don't think it's safe to modify last_syn outside of the spin lock. > >> This should be done above. > > > > This is the only writer, plus we are running under event_lock with > > interrupts off, so it is safe. > > The value will be read concurrently by evdev_fetch_next_event. So if > this were safe, then we wouldn't need the spin lock at all. The spinlock ensures atomic read/write of the event buffer. The position into the buffer does not need the lock. > At the very least for the sake of consistency, I think we should keep > the buffer manipulations within the guarded region. Sounds reasonable. Thanks, Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
