Add EVFILT_USER to kevents.

Add user events support to kernel events which are not associated with any
kernel mechanism but are triggered by user level code.  This is useful for
adding user level events to an event handler that may also be monitoring
kernel events.

Approved by:	rwatson (co-mentor)

1 files changed, 99 insertions, 0 deletions

diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index cf402a2..92afec2 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -142,6 +142,10 @@ static void	filt_timerexpire(void *knx);
 static int	filt_timerattach(struct knote *kn);
 static void	filt_timerdetach(struct knote *kn);
 static int	filt_timer(struct knote *kn, long hint);
+static int	filt_userattach(struct knote *kn);
+static void	filt_userdetach(struct knote *kn);
+static int	filt_user(struct knote *kn, long hint);
+static void	filt_usertouch(struct knote *kn, struct kevent *kev, long type);
 
 static struct filterops file_filtops = {
 	.f_isfd = 1,
@@ -165,6 +169,12 @@ static struct filterops timer_filtops = {
 	.f_detach = filt_timerdetach,
 	.f_event = filt_timer,
 };
+static struct filterops user_filtops = {
+	.f_attach = filt_userattach,
+	.f_detach = filt_userdetach,
+	.f_event = filt_user,
+	.f_touch = filt_usertouch,
+};
 
 static uma_zone_t	knote_zone;
 static int 		kq_ncallouts = 0;
@@ -271,6 +281,7 @@ static struct {
 	{ &file_filtops },			/* EVFILT_NETDEV */
 	{ &fs_filtops },			/* EVFILT_FS */
 	{ &null_filtops },			/* EVFILT_LIO */
+	{ &user_filtops },			/* EVFILT_USER */
 };
 
 /*
@@ -573,6 +584,94 @@ filt_timer(struct knote *kn, long hint)
 	return (kn->kn_data != 0);
 }
 
+static int
+filt_userattach(struct knote *kn)
+{
+
+	/* 
+	 * EVFILT_USER knotes are not attached to anything in the kernel.
+	 */ 
+	kn->kn_hook = NULL;
+	if (kn->kn_fflags & NOTE_TRIGGER)
+		kn->kn_hookid = 1;
+	else
+		kn->kn_hookid = 0;
+	return (0);
+}
+
+static void
+filt_userdetach(__unused struct knote *kn)
+{
+
+	/*
+	 * EVFILT_USER knotes are not attached to anything in the kernel.
+	 */
+}
+
+static int
+filt_user(struct knote *kn, __unused long hint)
+{
+
+	return (kn->kn_hookid);
+}
+
+static void
+filt_usertouch(struct knote *kn, struct kevent *kev, long type)
+{
+	int ffctrl;
+
+	switch (type) {
+	case EVENT_REGISTER:
+		if (kev->fflags & NOTE_TRIGGER)
+			kn->kn_hookid = 1;
+
+		ffctrl = kev->fflags & NOTE_FFCTRLMASK;
+		kev->fflags &= NOTE_FFLAGSMASK;
+		switch (ffctrl) {
+		case NOTE_FFNOP:
+			break;
+
+		case NOTE_FFAND:
+			kn->kn_sfflags &= kev->fflags;
+			break;
+
+		case NOTE_FFOR:
+			kn->kn_sfflags |= kev->fflags;
+			break;
+
+		case NOTE_FFCOPY:
+			kn->kn_sfflags = kev->fflags;
+			break;
+
+		default:
+			/* XXX Return error? */
+			break;
+		}
+		kn->kn_sdata = kev->data;
+		if (kev->flags & EV_CLEAR) {
+			kn->kn_hookid = 0;
+			kn->kn_data = 0;
+			kn->kn_fflags = 0;
+		}
+		break;
+
+        case EVENT_PROCESS:
+		*kev = kn->kn_kevent;
+		kev->fflags = kn->kn_sfflags;
+		kev->data = kn->kn_sdata;
+		if (kn->kn_flags & EV_CLEAR) {
+			kn->kn_hookid = 0;
+			kn->kn_data = 0;
+			kn->kn_fflags = 0;
+		}
+		break;
+
+	default:
+		panic("filt_usertouch() - invalid type (%ld)", type);
+		break;
+	}
+}
+
 int
 kqueue(struct thread *td, struct kqueue_args *uap)
 {