Add in kqueue support to LIO event notification and fix how it handled

notifications when LIO operations completed.  These were the problems
with LIO event complete notification:
      -	Move all LIO/AIO event notification into one general function
	so we don't have bugs in different data paths.  This unification
	got rid of several notification bugs one of which if kqueue was
	used a SIGILL could get sent to the process.
      -	Change the LIO event accounting to count all AIO request that
	could have been split across the fast path and daemon mode.
	The prior accounting only kept track of AIO op's in that
	mode and not the entire list of operations.  This could cause
	a bogus LIO event complete notification to occur when all of
	the fast path AIO op's completed and not the AIO op's that
	ended up queued for the daemon.

Suggestions from:	alc

1 files changed, 6 insertions, 2 deletions

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 3aa4550243b9..341910162454 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -247,6 +247,7 @@ static struct {
 	{ &timer_filtops },			/* EVFILT_TIMER */
 	{ &file_filtops },			/* EVFILT_NETDEV */
 	{ &fs_filtops },			/* EVFILT_FS */
+	{ &null_filtops },			/* EVFILT_LIO */
 };
 
 /*
@@ -633,6 +634,8 @@ kern_kevent(struct thread *td, int fd, int nchanges, int nevents,
 		changes = keva;
 		for (i = 0; i < n; i++) {
 			kevp = &changes[i];
+			if (!kevp->filter)
+				continue;
 			kevp->flags &= ~EV_SYSFLAGS;
 			error = kqueue_register(kq, kevp, td, 1);
 			if (error) {
@@ -1828,7 +1831,7 @@ knote_attach(struct knote *kn, struct kqueue *kq)
 }
 
 /*
- * knote must already have been detatched using the f_detach method.
+ * knote must already have been detached using the f_detach method.
  * no lock need to be held, it is assumed that the KN_INFLUX flag is set
  * to prevent other removal.
  */
@@ -1850,7 +1853,8 @@ knote_drop(struct knote *kn, struct thread *td)
 	else
 		list = &kq->kq_knhash[KN_HASH(kn->kn_id, kq->kq_knhashmask)];
 
-	SLIST_REMOVE(list, kn, knote, kn_link);
+	if (!SLIST_EMPTY(list))
+		SLIST_REMOVE(list, kn, knote, kn_link);
 	if (kn->kn_status & KN_QUEUED)
 		knote_dequeue(kn);
 	KQ_UNLOCK_FLUX(kq);