32 files changed, 471 insertions, 256 deletions

diff --git a/sys/dev/si/si.c b/sys/dev/si/si.c
index 603dcf698d08..1acfb290a9d7 100644
--- a/sys/dev/si/si.c
+++ b/sys/dev/si/si.c
@@ -131,8 +131,9 @@ static struct cdevsw si_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 static int si_Nports;
diff --git a/sys/dev/streams/streams.c b/sys/dev/streams/streams.c
index f4c89e06d0ee..4aa4c755b9bb 100644
--- a/sys/dev/streams/streams.c
+++ b/sys/dev/streams/streams.c
@@ -99,7 +99,8 @@ dev_t dt_ptm, dt_arp, dt_icmp, dt_ip, dt_tcp, dt_udp, dt_rawip,
 	dt_unix_dgram, dt_unix_stream, dt_unix_ord_stream;
 
 static struct fileops svr4_netops = {
-	soo_read, soo_write, soo_ioctl, soo_poll, soo_stat, svr4_soo_close
+	soo_read, soo_write, soo_ioctl, soo_poll, sokqfilter,
+	soo_stat, svr4_soo_close
 };
  
 #define CDEV_MAJOR 103
diff --git a/sys/dev/usb/umodem.c b/sys/dev/usb/umodem.c
index 0ba4ab387dbf..cb2849f2ab38 100644
--- a/sys/dev/usb/umodem.c
+++ b/sys/dev/usb/umodem.c
@@ -167,8 +167,9 @@ static struct cdevsw umodem_cdevsw = {
 	/* maj */       UMODEM_CDEV_MAJOR,
 	/* dump */      nodump,
 	/* psize */     nopsize,
-	/* flags */     D_TTY,
-	/* bmaj */      -1
+	/* flags */     D_TTY | D_KQFILTER,
+	/* bmaj */      -1,
+	/* kqfilter */	ttykqfilter,
 };
 #endif
 
diff --git a/sys/gnu/i386/isa/dgb.c b/sys/gnu/i386/isa/dgb.c
index f054e7baae3f..28897fcf8f52 100644
--- a/sys/gnu/i386/isa/dgb.c
+++ b/sys/gnu/i386/isa/dgb.c
@@ -218,8 +218,9 @@ static struct cdevsw dgb_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 static	speed_t	dgbdefaultrate = TTYDEF_SPEED;
diff --git a/sys/gnu/i386/isa/dgm.c b/sys/gnu/i386/isa/dgm.c
index 18122f00db65..594fba6dfb9c 100644
--- a/sys/gnu/i386/isa/dgm.c
+++ b/sys/gnu/i386/isa/dgm.c
@@ -221,8 +221,9 @@ static struct cdevsw dgm_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 static	speed_t	dgmdefaultrate = TTYDEF_SPEED;
diff --git a/sys/i386/isa/cx.c b/sys/i386/isa/cx.c
index 3bca982abb51..876e63361fbd 100644
--- a/sys/i386/isa/cx.c
+++ b/sys/i386/isa/cx.c
@@ -101,8 +101,9 @@ struct cdevsw cx_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 #else
 struct tty *cx_tty [NCX*NCHAN];         /* tty data */
diff --git a/sys/i386/isa/cy.c b/sys/i386/isa/cy.c
index dfeb69ac11e5..925666abf842 100644
--- a/sys/i386/isa/cy.c
+++ b/sys/i386/isa/cy.c
@@ -383,8 +383,9 @@ static struct cdevsw sio_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 static	int	comconsole = -1;
diff --git a/sys/i386/isa/istallion.c b/sys/i386/isa/istallion.c
index 816773b444b3..b5def9c06d3b 100644
--- a/sys/i386/isa/istallion.c
+++ b/sys/i386/isa/istallion.c
@@ -647,8 +647,9 @@ static struct cdevsw stli_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 #endif
diff --git a/sys/i386/isa/pcvt/pcvt_drv.c b/sys/i386/isa/pcvt/pcvt_drv.c
index 5c50173ac4ea..3a470cce6023 100644
--- a/sys/i386/isa/pcvt/pcvt_drv.c
+++ b/sys/i386/isa/pcvt/pcvt_drv.c
@@ -114,8 +114,9 @@ static struct cdevsw pc_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 #if PCVT_NETBSD > 100	/* NetBSD-current Feb 20 1995 */
diff --git a/sys/i386/isa/rc.c b/sys/i386/isa/rc.c
index ce6dab2cd789..6b478c7e716d 100644
--- a/sys/i386/isa/rc.c
+++ b/sys/i386/isa/rc.c
@@ -102,8 +102,9 @@ static struct cdevsw rc_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 /* Per-board structure */
diff --git a/sys/i386/isa/rp.c b/sys/i386/isa/rp.c
index 67f65bb7a461..40a5e3b49e8f 100644
--- a/sys/i386/isa/rp.c
+++ b/sys/i386/isa/rp.c
@@ -811,8 +811,9 @@ static struct cdevsw rp_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 static int rp_controller_port = 0;
diff --git a/sys/i386/isa/stallion.c b/sys/i386/isa/stallion.c
index 4194878de99d..717c9c0f2aa6 100644
--- a/sys/i386/isa/stallion.c
+++ b/sys/i386/isa/stallion.c
@@ -540,8 +540,9 @@ static struct cdevsw stl_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 static void stl_drvinit(void *unused)
diff --git a/sys/isa/sio.c b/sys/isa/sio.c
index 0894e84e3913..cd32ef7f0e30 100644
--- a/sys/isa/sio.c
+++ b/sys/isa/sio.c
@@ -398,8 +398,9 @@ static struct cdevsw sio_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 int	comconsole = -1;
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index eb43b075cf96..9a88e6dce285 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -93,6 +93,7 @@ static int badfo_ioctl __P((struct file *fp, u_long com, caddr_t data,
     struct proc *p));
 static int badfo_poll __P((struct file *fp, int events,
     struct ucred *cred, struct proc *p));
+static int badfo_kqfilter __P((struct file *fp, struct knote *kn));
 static int badfo_stat __P((struct file *fp, struct stat *sb, struct proc *p));
 static int badfo_close __P((struct file *fp, struct proc *p));
 
@@ -1480,6 +1481,7 @@ struct fileops badfileops = {
 	badfo_readwrite,
 	badfo_ioctl,
 	badfo_poll,
+	badfo_kqfilter,
 	badfo_stat,
 	badfo_close
 };
@@ -1519,6 +1521,15 @@ badfo_poll(fp, events, cred, p)
 }
 
 static int
+badfo_kqfilter(fp, kn)
+	struct file *fp;
+	struct knote *kn;
+{
+
+	return (0);
+}
+
+static int
 badfo_stat(fp, sb, p)
 	struct file *fp;
 	struct stat *sb;
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index c51af29e91b5..8bb34c609bb2 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 1999,2000 Jonathan Lemon <jlemon@FreeBSD.org>
+ * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -48,15 +48,6 @@
 
 #include <vm/vm_zone.h>
 
-static int 	filt_nullattach(struct knote *kn);
-static int 	filt_rwtypattach(struct knote *kn);
-static int	filt_kqattach(struct knote *kn);
-static void	filt_kqdetach(struct knote *kn);
-static int	filt_kqueue(struct knote *kn, long hint);
-static int	filt_procattach(struct knote *kn);
-static void	filt_procdetach(struct knote *kn);
-static int	filt_proc(struct knote *kn, long hint);
-
 static int	kqueue_scan(struct file *fp, int maxevents,
 		    struct kevent *ulistp, const struct timespec *timeout,
 		    struct proc *p);
@@ -68,10 +59,21 @@ static int	kqueue_ioctl(struct file *fp, u_long com, caddr_t data,
 		    struct proc *p);
 static int 	kqueue_poll(struct file *fp, int events, struct ucred *cred,
 		    struct proc *p);
+static int 	kqueue_kqfilter(struct file *fp, struct knote *kn);
 static int 	kqueue_stat(struct file *fp, struct stat *st, struct proc *p);
 static int 	kqueue_close(struct file *fp, struct proc *p);
 static void 	kqueue_wakeup(struct kqueue *kq);
 
+static struct fileops kqueueops = {
+	kqueue_read,
+	kqueue_write,
+	kqueue_ioctl,
+	kqueue_poll,
+	kqueue_kqfilter,
+	kqueue_stat,
+	kqueue_close
+};
+
 static void 	knote_attach(struct knote *kn, struct filedesc *fdp);
 static void 	knote_drop(struct knote *kn, struct proc *p);
 static void 	knote_enqueue(struct knote *kn);
@@ -80,6 +82,20 @@ static void 	knote_init(void);
 static struct 	knote *knote_alloc(void);
 static void 	knote_free(struct knote *kn);
 
+static void	filt_kqdetach(struct knote *kn);
+static int	filt_kqueue(struct knote *kn, long hint);
+static int	filt_procattach(struct knote *kn);
+static void	filt_procdetach(struct knote *kn);
+static int	filt_proc(struct knote *kn, long hint);
+static int	filt_fileattach(struct knote *kn);
+
+static struct filterops kqread_filtops =
+	{ 1, NULL, filt_kqdetach, filt_kqueue };
+static struct filterops proc_filtops =
+	{ 0, filt_procattach, filt_procdetach, filt_proc };
+static struct filterops file_filtops =
+	{ 1, filt_fileattach, NULL, NULL };
+
 static vm_zone_t	knote_zone;
 
 #define KNOTE_ACTIVATE(kn) do { 					\
@@ -91,85 +107,38 @@ static vm_zone_t	knote_zone;
 #define	KN_HASHSIZE		64		/* XXX should be tunable */
 #define KN_HASH(val, mask)	(((val) ^ (val >> 8)) & (mask))
 
-static struct fileops kqueueops = {
-	kqueue_read,
-	kqueue_write,
-	kqueue_ioctl,
-	kqueue_poll,
-	kqueue_stat,
-	kqueue_close
-};
-
-extern struct filterops so_rwfiltops[];
-extern struct filterops fifo_rwfiltops[];
-extern struct filterops pipe_rwfiltops[];
-extern struct filterops vn_rwfiltops[];
-
-static struct filterops kq_rwfiltops[] = {
-    { 1, filt_kqattach, filt_kqdetach, filt_kqueue },
-    { 1, filt_nullattach, NULL, NULL },
-};
-
 extern struct filterops aio_filtops;
 extern struct filterops sig_filtops;
-extern struct filterops vn_filtops;
-
-static struct filterops rwtype_filtops =
-	{ 1, filt_rwtypattach, NULL, NULL };
-static struct filterops proc_filtops =
-	{ 0, filt_procattach, filt_procdetach, filt_proc };
-
-/*
- * XXX
- * These must match the order of defines in <sys/file.h>
- */
-static struct filterops *rwtypfilt_sw[] = {
-	NULL,				/* 0 */
-	vn_rwfiltops,			/* DTYPE_VNODE */
-	so_rwfiltops,			/* DTYPE_SOCKET */
-	pipe_rwfiltops,			/* DTYPE_PIPE */
-	fifo_rwfiltops,			/* DTYPE_FIFO */
-	kq_rwfiltops,			/* DTYPE_KQUEUE */
-};
 
 /*
- * table for for all system-defined filters.
+ * Table for for all system-defined filters.
  */
 static struct filterops *sysfilt_ops[] = {
-	&rwtype_filtops,		/* EVFILT_READ */
-	&rwtype_filtops,		/* EVFILT_WRITE */
+	&file_filtops,			/* EVFILT_READ */
+	&file_filtops,			/* EVFILT_WRITE */
 	&aio_filtops,			/* EVFILT_AIO */
-	&vn_filtops,			/* EVFILT_VNODE */
+	&file_filtops,			/* EVFILT_VNODE */
 	&proc_filtops,			/* EVFILT_PROC */
 	&sig_filtops,			/* EVFILT_SIGNAL */
 };
 
 static int
-filt_nullattach(struct knote *kn)
-{
-	return (ENXIO);
-}
-
-/*
- * file-type specific attach routine for read/write filters
- */
-static int
-filt_rwtypattach(struct knote *kn)
+filt_fileattach(struct knote *kn)
 {
-	struct filterops *fops;
-
-	fops = rwtypfilt_sw[kn->kn_fp->f_type];
-	if (fops == NULL)
-		return (EINVAL);
-	kn->kn_fop = &fops[~kn->kn_filter];	/* convert to 0-base index */
-	return (kn->kn_fop->f_attach(kn));
+	
+	return (fo_kqfilter(kn->kn_fp, kn));
 }
 
+/*ARGSUSED*/
 static int
-filt_kqattach(struct knote *kn)
+kqueue_kqfilter(struct file *fp, struct knote *kn)
 {
 	struct kqueue *kq = (struct kqueue *)kn->kn_fp->f_data;
 
+	if (kn->kn_filter != EVFILT_READ)
+		return (1);
+
+	kn->kn_fop = &kqread_filtops;
 	SLIST_INSERT_HEAD(&kq->kq_sel.si_note, kn, kn_selnext);
 	return (0);
 }
@@ -466,7 +435,7 @@ kqueue_register(struct kqueue *kq, struct kevent *kev, struct proc *p)
 			kn->kn_fop = fops;
 
 			/*
-			 * apply reference count to knode structure, so
+			 * apply reference count to knote structure, and
 			 * do not release it at the end of this routine.
 			 */
 			fp = NULL;
diff --git a/sys/kern/subr_xxx.c b/sys/kern/subr_xxx.c
index 6819fb38c57a..f3fd2ed2493b 100644
--- a/sys/kern/subr_xxx.c
+++ b/sys/kern/subr_xxx.c
@@ -134,6 +134,15 @@ noioctl(dev, cmd, data, flags, p)
 }
 
 int
+nokqfilter(dev, kn)
+	dev_t dev;
+	struct knote *kn;
+{
+
+	return (ENODEV);
+}
+
+int
 nommap(dev, offset, nprot)
 	dev_t dev;
 	vm_offset_t offset;
diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c
index 2a7084942a28..a4fb966f58f9 100644
--- a/sys/kern/sys_pipe.c
+++ b/sys/kern/sys_pipe.c
@@ -95,21 +95,24 @@ static int pipe_write __P((struct file *fp, struct uio *uio,
 static int pipe_close __P((struct file *fp, struct proc *p));
 static int pipe_poll __P((struct file *fp, int events, struct ucred *cred,
 		struct proc *p));
+static int pipe_kqfilter __P((struct file *fp, struct knote *kn));
 static int pipe_stat __P((struct file *fp, struct stat *sb, struct proc *p));
 static int pipe_ioctl __P((struct file *fp, u_long cmd, caddr_t data, struct proc *p));
 
-static struct fileops pipeops =
-    { pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_stat, pipe_close };
+static struct fileops pipeops = {
+	pipe_read, pipe_write, pipe_ioctl, pipe_poll, pipe_kqfilter,
+	pipe_stat, pipe_close
+};
 
-static int	filt_pipeattach(struct knote *kn);
 static void	filt_pipedetach(struct knote *kn);
 static int	filt_piperead(struct knote *kn, long hint);
 static int	filt_pipewrite(struct knote *kn, long hint);
 
-struct filterops pipe_rwfiltops[] = {
-	{ 1, filt_pipeattach, filt_pipedetach, filt_piperead },
-	{ 1, filt_pipeattach, filt_pipedetach, filt_pipewrite },
-};
+static struct filterops pipe_rfiltops =
+	{ 1, NULL, filt_pipedetach, filt_piperead };
+static struct filterops pipe_wfiltops =
+	{ 1, NULL, filt_pipedetach, filt_pipewrite };
+
 
 /*
  * Default pipe buffer size(s), this can be kind-of large now because pipe
@@ -1185,11 +1188,23 @@ pipeclose(cpipe)
 	}
 }
 
+/*ARGSUSED*/
 static int
-filt_pipeattach(struct knote *kn)
+pipe_kqfilter(struct file *fp, struct knote *kn)
 {
 	struct pipe *rpipe = (struct pipe *)kn->kn_fp->f_data;
 
+	switch (kn->kn_filter) {
+	case EVFILT_READ:
+		kn->kn_fop = &pipe_rfiltops;
+		break;
+	case EVFILT_WRITE:
+		kn->kn_fop = &pipe_wfiltops;
+		break;
+	default:
+		return (1);
+	}
+	
 	SLIST_INSERT_HEAD(&rpipe->pipe_sel.si_note, kn, kn_selnext);
 	return (0);
 }
diff --git a/sys/kern/sys_socket.c b/sys/kern/sys_socket.c
index f58720b7e4a5..e4db298b339f 100644
--- a/sys/kern/sys_socket.c
+++ b/sys/kern/sys_socket.c
@@ -50,8 +50,10 @@
 #include <net/if.h>
 #include <net/route.h>
 
-struct	fileops socketops =
-    { soo_read, soo_write, soo_ioctl, soo_poll, soo_stat, soo_close };
+struct	fileops socketops = {
+	soo_read, soo_write, soo_ioctl, soo_poll, sokqfilter,
+	soo_stat, soo_close
+};
 
 /* ARGSUSED */
 int
diff --git a/sys/kern/tty.c b/sys/kern/tty.c
index c66036a69aaa..50d80b06702a 100644
--- a/sys/kern/tty.c
+++ b/sys/kern/tty.c
@@ -113,6 +113,10 @@ static void	ttyrub __P((int c, struct tty *tp));
 static void	ttyrubo __P((struct tty *tp, int cnt));
 static void	ttyunblock __P((struct tty *tp));
 static int	ttywflush __P((struct tty *tp));
+static int	filt_ttyread __P((struct knote *kn, long hint));
+static void 	filt_ttyrdetach __P((struct knote *kn));
+static int	filt_ttywrite __P((struct knote *kn, long hint));
+static void 	filt_ttywdetach __P((struct knote *kn));
 
 /*
  * Table with character classes and parity. The 8th bit indicates parity,
@@ -1085,6 +1089,89 @@ ttypoll(dev, events, p)
 	return (revents);
 }
 
+static struct filterops ttyread_filtops =
+	{ 1, NULL, filt_ttyrdetach, filt_ttyread };
+static struct filterops ttywrite_filtops =
+	{ 1, NULL, filt_ttywdetach, filt_ttywrite };
+
+int
+ttykqfilter(dev, kn)
+	dev_t dev;
+	struct knote *kn;
+{
+	struct tty *tp = dev->si_tty;
+	struct klist *klist;
+	int s;
+
+	switch (kn->kn_filter) {
+	case EVFILT_READ:
+		klist = &tp->t_rsel.si_note;
+		kn->kn_fop = &ttyread_filtops;
+		break;
+	case EVFILT_WRITE:
+		klist = &tp->t_wsel.si_note;
+		kn->kn_fop = &ttywrite_filtops;
+		break;
+	default:
+		return (1);
+	}
+
+	kn->kn_hook = (caddr_t)dev;
+
+	s = spltty();
+	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
+	splx(s);
+
+	return (0);
+}
+
+static void
+filt_ttyrdetach(struct knote *kn)
+{
+	struct tty *tp = ((dev_t)kn->kn_hook)->si_tty;
+	int s = spltty();
+
+	SLIST_REMOVE(&tp->t_rsel.si_note, kn, knote, kn_selnext);
+	splx(s);
+}
+
+static int
+filt_ttyread(struct knote *kn, long hint)
+{
+	struct tty *tp = ((dev_t)kn->kn_hook)->si_tty;
+
+	kn->kn_data = ttnread(tp);
+	if (ISSET(tp->t_state, TS_ZOMBIE)) {
+		kn->kn_flags |= EV_EOF;
+		return (1);
+	}
+	return (kn->kn_data > 0);
+}
+
+static void
+filt_ttywdetach(struct knote *kn)
+{
+	struct tty *tp = ((dev_t)kn->kn_hook)->si_tty;
+	int s = spltty();
+
+	SLIST_REMOVE(&tp->t_wsel.si_note, kn, knote, kn_selnext);
+	splx(s);
+}
+
+static int
+filt_ttywrite(kn, hint)
+	struct knote *kn;
+	long hint;
+{
+	struct tty *tp = ((dev_t)kn->kn_hook)->si_tty;
+
+	kn->kn_data = tp->t_outq.c_cc;
+	if (ISSET(tp->t_state, TS_ZOMBIE))
+		return (1);
+	return (kn->kn_data <= tp->t_olowat &&
+	    ISSET(tp->t_state, TS_CONNECTED));
+}
+
 /*
  * Must be called at spltty().
  */
@@ -2102,6 +2189,7 @@ ttwakeup(tp)
 	if (ISSET(tp->t_state, TS_ASYNC) && tp->t_sigio != NULL)
 		pgsigio(tp->t_sigio, SIGIO, (tp->t_session != NULL));
 	wakeup(TSA_HUP_OR_INPUT(tp));
+	KNOTE(&tp->t_rsel.si_note, 0);
 }
 
 /*
@@ -2126,6 +2214,7 @@ ttwwakeup(tp)
 		CLR(tp->t_state, TS_SO_OLOWAT);
 		wakeup(TSA_OLOWAT(tp));
 	}
+	KNOTE(&tp->t_wsel.si_note, 0);
 }
 
 /*
diff --git a/sys/kern/tty_cons.c b/sys/kern/tty_cons.c
index 784fecad98e2..9aa2c23386d6 100644
--- a/sys/kern/tty_cons.c
+++ b/sys/kern/tty_cons.c
@@ -58,6 +58,7 @@ static	d_read_t	cnread;
 static	d_write_t	cnwrite;
 static	d_ioctl_t	cnioctl;
 static	d_poll_t	cnpoll;
+static	d_kqfilter_t	cnkqfilter;
 
 #define	CDEV_MAJOR	0
 static struct cdevsw cn_cdevsw = {
@@ -73,8 +74,9 @@ static struct cdevsw cn_cdevsw = {
 	/* maj */	CDEV_MAJOR,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	cnkqfilter,
 };
 
 static dev_t	cn_dev_t; 	/* seems to be never really used */
@@ -398,6 +400,20 @@ cnpoll(dev, events, p)
 	return ((*devsw(dev)->d_poll)(dev, events, p));
 }
 
+static int
+cnkqfilter(dev, kn)
+	dev_t dev;
+	struct knote *kn;
+{
+	if ((cn_tab == NULL) || cn_mute)
+		return (1);
+
+	dev = cn_tab->cn_dev;
+	if (devsw(dev)->d_flags & D_KQFILTER)
+		return ((*devsw(dev)->d_kqfilter)(dev, kn));
+	return (1);
+}
+
 int
 cngetc()
 {
diff --git a/sys/kern/tty_pty.c b/sys/kern/tty_pty.c
index 14269c131616..744ff44c7af7 100644
--- a/sys/kern/tty_pty.c
+++ b/sys/kern/tty_pty.c
@@ -87,8 +87,9 @@ static struct cdevsw pts_cdevsw = {
 	/* maj */	CDEV_MAJOR_S,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 #define	CDEV_MAJOR_C	6
@@ -105,8 +106,9 @@ static struct cdevsw ptc_cdevsw = {
 	/* maj */	CDEV_MAJOR_C,
 	/* dump */	nodump,
 	/* psize */	nopsize,
-	/* flags */	D_TTY,
-	/* bmaj */	-1
+	/* flags */	D_TTY | D_KQFILTER,
+	/* bmaj */	-1,
+	/* kqfilter */	ttykqfilter,
 };
 
 #define BUFSIZ 100		/* Chunk size iomoved to/from user */
diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index dda845c8e880..0f04d17a94c5 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -64,21 +64,18 @@
 static int	 do_setopt_accept_filter(struct socket *so, struct sockopt *sopt);
 #endif /* INET */
 
-static int 	filt_sorattach(struct knote *kn);
 static void 	filt_sordetach(struct knote *kn);
 static int 	filt_soread(struct knote *kn, long hint);
-static int 	filt_sowattach(struct knote *kn);
 static void 	filt_sowdetach(struct knote *kn);
 static int	filt_sowrite(struct knote *kn, long hint);
 static int	filt_solisten(struct knote *kn, long hint);
 
 static struct filterops solisten_filtops = 
-	{ 1, filt_sorattach, filt_sordetach, filt_solisten };
-
-struct filterops so_rwfiltops[] = {
-	{ 1, filt_sorattach, filt_sordetach, filt_soread },
-	{ 1, filt_sowattach, filt_sowdetach, filt_sowrite },
-};
+	{ 1, NULL, filt_sordetach, filt_solisten };
+static struct filterops soread_filtops =
+	{ 1, NULL, filt_sordetach, filt_soread };
+static struct filterops sowrite_filtops = 
+	{ 1, NULL, filt_sowdetach, filt_sowrite };
 
 struct	vm_zone *socket_zone;
 so_gen_t	so_gencnt;	/* generation count for sockets */
@@ -1538,16 +1535,32 @@ sopoll(struct socket *so, int events, struct ucred *cred, struct proc *p)
 	return (revents);
 }
 
-static int
-filt_sorattach(struct knote *kn)
+int
+sokqfilter(struct file *fp, struct knote *kn)
 {
 	struct socket *so = (struct socket *)kn->kn_fp->f_data;
-	int s = splnet();
+	struct sockbuf *sb;
+	int s;
 
-	if (so->so_options & SO_ACCEPTCONN)
-		kn->kn_fop = &solisten_filtops;
-	SLIST_INSERT_HEAD(&so->so_rcv.sb_sel.si_note, kn, kn_selnext);
-	so->so_rcv.sb_flags |= SB_KNOTE;
+	switch (kn->kn_filter) {
+	case EVFILT_READ:
+		if (so->so_options & SO_ACCEPTCONN)
+			kn->kn_fop = &solisten_filtops;
+		else
+			kn->kn_fop = &soread_filtops;
+		sb = &so->so_rcv;
+		break;
+	case EVFILT_WRITE:
+		kn->kn_fop = &sowrite_filtops;
+		sb = &so->so_snd;
+		break;
+	default:
+		return (1);
+	}
+
+	s = splnet();
+	SLIST_INSERT_HEAD(&sb->sb_sel.si_note, kn, kn_selnext);
+	sb->sb_flags |= SB_KNOTE;
 	splx(s);
 	return (0);
 }
@@ -1573,25 +1586,16 @@ filt_soread(struct knote *kn, long hint)
 	kn->kn_data = so->so_rcv.sb_cc;
 	if (so->so_state & SS_CANTRCVMORE) {
 		kn->kn_flags |= EV_EOF; 
+		kn->kn_fflags = so->so_error;
 		return (1);
 	}
 	if (so->so_error)	/* temporary udp error */
 		return (1);
+	if (kn->kn_sfflags & NOTE_LOWAT)
+		return (kn->kn_data >= kn->kn_sdata);
 	return (kn->kn_data >= so->so_rcv.sb_lowat);
 }
 
-static int
-filt_sowattach(struct knote *kn)
-{
-	struct socket *so = (struct socket *)kn->kn_fp->f_data;
-	int s = splnet();
-
-	SLIST_INSERT_HEAD(&so->so_snd.sb_sel.si_note, kn, kn_selnext);
-	so->so_snd.sb_flags |= SB_KNOTE;
-	splx(s);
-	return (0);
-}
-
 static void
 filt_sowdetach(struct knote *kn)
 {
@@ -1613,6 +1617,7 @@ filt_sowrite(struct knote *kn, long hint)
 	kn->kn_data = sbspace(&so->so_snd);
 	if (so->so_state & SS_CANTSENDMORE) {
 		kn->kn_flags |= EV_EOF; 
+		kn->kn_fflags = so->so_error;
 		return (1);
 	}
 	if (so->so_error)	/* temporary udp error */
@@ -1620,6 +1625,8 @@ filt_sowrite(struct knote *kn, long hint)
 	if (((so->so_state & SS_ISCONNECTED) == 0) &&
 	    (so->so_proto->pr_flags & PR_CONNREQUIRED))
 		return (0);
+	if (kn->kn_sfflags & NOTE_LOWAT)
+		return (kn->kn_data >= kn->kn_sdata);
 	return (kn->kn_data >= so->so_snd.sb_lowat);
 }
 
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index 16a0c9c01862..1af02518d601 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -53,9 +53,6 @@
 #include <sys/ttycom.h>
 #include <sys/conf.h>
 
-#include <ufs/ufs/quota.h>
-#include <ufs/ufs/inode.h>
-
 static int vn_closefile __P((struct file *fp, struct proc *p));
 static int vn_ioctl __P((struct file *fp, u_long com, caddr_t data, 
 		struct proc *p));
@@ -63,30 +60,14 @@ static int vn_read __P((struct file *fp, struct uio *uio,
 		struct ucred *cred, int flags, struct proc *p));
 static int vn_poll __P((struct file *fp, int events, struct ucred *cred,
 		struct proc *p));
+static int vn_kqfilter __P((struct file *fp, struct knote *kn));
 static int vn_statfile __P((struct file *fp, struct stat *sb, struct proc *p));
 static int vn_write __P((struct file *fp, struct uio *uio, 
 		struct ucred *cred, int flags, struct proc *p));
 
-struct 	fileops vnops =
-	{ vn_read, vn_write, vn_ioctl, vn_poll, vn_statfile, vn_closefile };
-
-static int	filt_nullattach(struct knote *kn);
-static int	filt_vnattach(struct knote *kn);
-static void	filt_vndetach(struct knote *kn);
-static int	filt_vnode(struct knote *kn, long hint);
-static int	filt_vnread(struct knote *kn, long hint);
-
-struct filterops vn_filtops =
-	{ 1, filt_vnattach, filt_vndetach, filt_vnode };
-
-/*
- * XXX
- * filt_vnread is ufs-specific, so the attach routine should really
- * switch out to different filterops based on the vn filetype
- */
-struct filterops vn_rwfiltops[] = {
-	{ 1, filt_vnattach, filt_vndetach, filt_vnread },
-	{ 1, filt_nullattach, NULL, NULL },
+struct 	fileops vnops = {
+	vn_read, vn_write, vn_ioctl, vn_poll, vn_kqfilter,
+	vn_statfile, vn_closefile
 };
 
 /*
@@ -664,64 +645,8 @@ vn_closefile(fp, p)
 }
 
 static int
-filt_vnattach(struct knote *kn)
-{
-	struct vnode *vp;
-
-	if (kn->kn_fp->f_type != DTYPE_VNODE &&
-	    kn->kn_fp->f_type != DTYPE_FIFO)
-		return (EBADF);
-
-	vp = (struct vnode *)kn->kn_fp->f_data;
-
-	/*
-	 * XXX
-	 * this is a hack simply to cause the filter attach to fail
-	 * for non-ufs filesystems, until the support for them is done.
-	 */
-	if ((vp)->v_tag != VT_UFS)
-		return (EOPNOTSUPP);
-
-        simple_lock(&vp->v_pollinfo.vpi_lock);
-	SLIST_INSERT_HEAD(&vp->v_pollinfo.vpi_selinfo.si_note, kn, kn_selnext);
-        simple_unlock(&vp->v_pollinfo.vpi_lock);
-
-	return (0);
-}
-
-static void
-filt_vndetach(struct knote *kn)
-{
-	struct vnode *vp = (struct vnode *)kn->kn_fp->f_data;
-
-        simple_lock(&vp->v_pollinfo.vpi_lock);
-	SLIST_REMOVE(&vp->v_pollinfo.vpi_selinfo.si_note,
-	    kn, knote, kn_selnext);
-        simple_unlock(&vp->v_pollinfo.vpi_lock);
-}
-
-static int
-filt_vnode(struct knote *kn, long hint)
-{
-
-	if (kn->kn_sfflags & hint)
-		kn->kn_fflags |= hint;
-	return (kn->kn_fflags != 0);
-}
-
-static int
-filt_nullattach(struct knote *kn)
-{
-	return (ENXIO);
-}
-
-/*ARGSUSED*/
-static int
-filt_vnread(struct knote *kn, long hint)
+vn_kqfilter(struct file *fp, struct knote *kn)
 {
-	struct vnode *vp = (struct vnode *)kn->kn_fp->f_data;
-	struct inode *ip = VTOI(vp);
 
-	kn->kn_data = ip->i_size - kn->kn_fp->f_offset;
-	return (kn->kn_data != 0);
+	return (VOP_KQFILTER(((struct vnode *)fp->f_data), kn));
 }
diff --git a/sys/kern/vnode_if.src b/sys/kern/vnode_if.src
index c40d3497846d..26ef2ea11fb5 100644
--- a/sys/kern/vnode_if.src
+++ b/sys/kern/vnode_if.src
@@ -222,6 +222,14 @@ vop_poll {
 };
 
 #
+#% kqfilter	vp	U U U
+#
+vop_kqfilter {
+	IN struct vnode *vp;
+	IN struct knote *kn;
+};
+
+#
 #% revoke	vp	U U U
 #
 vop_revoke {
diff --git a/sys/miscfs/fifofs/fifo_vnops.c b/sys/miscfs/fifofs/fifo_vnops.c
index 5bd13a771d48..cd7dcfbc34ba 100644
--- a/sys/miscfs/fifofs/fifo_vnops.c
+++ b/sys/miscfs/fifofs/fifo_vnops.c
@@ -71,23 +71,22 @@ static int	fifo_read __P((struct vop_read_args *));
 static int	fifo_write __P((struct vop_write_args *));
 static int	fifo_ioctl __P((struct vop_ioctl_args *));
 static int	fifo_poll __P((struct vop_poll_args *));
+static int	fifo_kqfilter __P((struct vop_kqfilter_args *));
 static int	fifo_inactive __P((struct  vop_inactive_args *));
 static int	fifo_bmap __P((struct vop_bmap_args *));
 static int	fifo_pathconf __P((struct vop_pathconf_args *));
 static int	fifo_advlock __P((struct vop_advlock_args *));
 
-static int	filt_fiforattach(struct knote *kn);
 static void	filt_fifordetach(struct knote *kn);
 static int	filt_fiforead(struct knote *kn, long hint);
-static int	filt_fifowattach(struct knote *kn);
 static void	filt_fifowdetach(struct knote *kn);
 static int	filt_fifowrite(struct knote *kn, long hint);
 
-struct filterops fifo_rwfiltops[] = {
-	{ 1, filt_fiforattach, filt_fifordetach, filt_fiforead },
-	{ 1, filt_fifowattach, filt_fifowdetach, filt_fifowrite },
-};
-
+static struct filterops fiforead_filtops =
+	{ 1, NULL, filt_fifordetach, filt_fiforead };
+static struct filterops fifowrite_filtops =
+	{ 1, NULL, filt_fifowdetach, filt_fifowrite };
+  
 vop_t **fifo_vnodeop_p;
 static struct vnodeopv_entry_desc fifo_vnodeop_entries[] = {
 	{ &vop_default_desc,		(vop_t *) vop_defaultop },
@@ -107,6 +106,7 @@ static struct vnodeopv_entry_desc fifo_vnodeop_entries[] = {
 	{ &vop_open_desc,		(vop_t *) fifo_open },
 	{ &vop_pathconf_desc,		(vop_t *) fifo_pathconf },
 	{ &vop_poll_desc,		(vop_t *) fifo_poll },
+	{ &vop_kqfilter_desc,		(vop_t *) fifo_kqfilter },
 	{ &vop_print_desc,		(vop_t *) fifo_print },
 	{ &vop_read_desc,		(vop_t *) fifo_read },
 	{ &vop_readdir_desc,		(vop_t *) fifo_badop },
@@ -355,22 +355,42 @@ fifo_ioctl(ap)
 	return (0);
 }
 
+/* ARGSUSED */
 static int
-filt_fiforattach(struct knote *kn)
+fifo_kqfilter(ap)
+	struct vop_kqfilter_args /* {
+		struct vnode *a_vp;
+		struct knote *a_kn;
+	} */ *ap;
 {
-	struct vnode *vn = (struct vnode *)kn->kn_fp->f_data;
-	struct socket *so = (struct socket *)vn->v_fifoinfo->fi_readsock;
+	struct socket *so = (struct socket *)ap->a_vp->v_fifoinfo->fi_readsock;
+	struct sockbuf *sb;
+
+	switch (ap->a_kn->kn_filter) {
+	case EVFILT_READ:
+		ap->a_kn->kn_fop = &fiforead_filtops;
+		sb = &so->so_rcv;
+		break;
+	case EVFILT_WRITE:
+		ap->a_kn->kn_fop = &fifowrite_filtops;
+		sb = &so->so_snd;
+		break;
+	default:
+		return (1);
+	}
+
+	ap->a_kn->kn_hook = (caddr_t)so;
+
+	SLIST_INSERT_HEAD(&sb->sb_sel.si_note, ap->a_kn, kn_selnext);
+	sb->sb_flags |= SB_KNOTE;
 
-	SLIST_INSERT_HEAD(&so->so_rcv.sb_sel.si_note, kn, kn_selnext);
-	so->so_rcv.sb_flags |= SB_KNOTE;
 	return (0);
 }
 
 static void
 filt_fifordetach(struct knote *kn)
 {
-	struct vnode *vn = (struct vnode *)kn->kn_fp->f_data;
-	struct socket *so = (struct socket *)vn->v_fifoinfo->fi_readsock;
+	struct socket *so = (struct socket *)kn->kn_hook;
 
 	SLIST_REMOVE(&so->so_rcv.sb_sel.si_note, kn, knote, kn_selnext);
 	if (SLIST_EMPTY(&so->so_rcv.sb_sel.si_note))
@@ -380,8 +400,7 @@ filt_fifordetach(struct knote *kn)
 static int
 filt_fiforead(struct knote *kn, long hint)
 {
-	struct vnode *vn = (struct vnode *)kn->kn_fp->f_data;
-	struct socket *so = (struct socket *)vn->v_fifoinfo->fi_readsock;
+	struct socket *so = (struct socket *)kn->kn_hook;
 
 	kn->kn_data = so->so_rcv.sb_cc;
 	if (so->so_state & SS_CANTRCVMORE) {
@@ -392,22 +411,10 @@ filt_fiforead(struct knote *kn, long hint)
 	return (kn->kn_data > 0);
 }
 
-static int
-filt_fifowattach(struct knote *kn)
-{
-	struct vnode *vn = (struct vnode *)kn->kn_fp->f_data;
-	struct socket *so = (struct socket *)vn->v_fifoinfo->fi_writesock;
-
-	SLIST_INSERT_HEAD(&so->so_snd.sb_sel.si_note, kn, kn_selnext);
-	so->so_rcv.sb_flags |= SB_KNOTE;
-	return (0);
-}
-
 static void
 filt_fifowdetach(struct knote *kn)
 {
-	struct vnode *vn = (struct vnode *)kn->kn_fp->f_data;
-	struct socket *so = (struct socket *)vn->v_fifoinfo->fi_readsock;
+	struct socket *so = (struct socket *)kn->kn_hook;
 
 	SLIST_REMOVE(&so->so_snd.sb_sel.si_note, kn, knote, kn_selnext);
 	if (SLIST_EMPTY(&so->so_snd.sb_sel.si_note))
@@ -417,8 +424,7 @@ filt_fifowdetach(struct knote *kn)
 static int
 filt_fifowrite(struct knote *kn, long hint)
 {
-	struct vnode *vn = (struct vnode *)kn->kn_fp->f_data;
-	struct socket *so = (struct socket *)vn->v_fifoinfo->fi_readsock;
+	struct socket *so = (struct socket *)kn->kn_hook;
 
 	kn->kn_data = sbspace(&so->so_snd);
 	if (so->so_state & SS_CANTSENDMORE) {
diff --git a/sys/miscfs/specfs/spec_vnops.c b/sys/miscfs/specfs/spec_vnops.c
index 7a3741ad90d2..f9ee56857dd0 100644
--- a/sys/miscfs/specfs/spec_vnops.c
+++ b/sys/miscfs/specfs/spec_vnops.c
@@ -62,6 +62,7 @@ static int	spec_inactive __P((struct  vop_inactive_args *));
 static int	spec_ioctl __P((struct vop_ioctl_args *));
 static int	spec_open __P((struct vop_open_args *));
 static int	spec_poll __P((struct vop_poll_args *));
+static int	spec_kqfilter __P((struct vop_kqfilter_args *));
 static int	spec_print __P((struct vop_print_args *));
 static int	spec_read __P((struct vop_read_args *));  
 static int	spec_strategy __P((struct vop_strategy_args *));
@@ -87,6 +88,7 @@ static struct vnodeopv_entry_desc spec_vnodeop_entries[] = {
 	{ &vop_open_desc,		(vop_t *) spec_open },
 	{ &vop_pathconf_desc,		(vop_t *) vop_stdpathconf },
 	{ &vop_poll_desc,		(vop_t *) spec_poll },
+	{ &vop_kqfilter_desc,		(vop_t *) spec_kqfilter },
 	{ &vop_print_desc,		(vop_t *) spec_print },
 	{ &vop_read_desc,		(vop_t *) spec_read },
 	{ &vop_readdir_desc,		(vop_t *) vop_panic },
@@ -320,6 +322,23 @@ spec_poll(ap)
 	dev = ap->a_vp->v_rdev;
 	return (*devsw(dev)->d_poll)(dev, ap->a_events, ap->a_p);
 }
+
+/* ARGSUSED */
+static int
+spec_kqfilter(ap)
+	struct vop_kqfilter_args /* {
+		struct vnode *a_vp;
+		struct knote *a_kn;
+	} */ *ap;
+{
+	dev_t dev;
+
+	dev = ap->a_vp->v_rdev;
+	if (devsw(dev)->d_flags & D_KQFILTER)
+		return (*devsw(dev)->d_kqfilter)(dev, ap->a_kn);
+	return (1);
+}
+
 /*
  * Synch buffers associated with a block device
  */
diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 263613c4a23b..7b71ed5dc8a1 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@ -100,6 +100,7 @@ struct specinfo {
 struct buf;
 struct proc;
 struct uio;
+struct knote;
 
 typedef int d_open_t __P((dev_t dev, int oflags, int devtype, struct proc *p));
 typedef int d_close_t __P((dev_t dev, int fflag, int devtype, struct proc *p));
@@ -113,6 +114,7 @@ typedef int d_psize_t __P((dev_t dev));
 typedef int d_read_t __P((dev_t dev, struct uio *uio, int ioflag));
 typedef int d_write_t __P((dev_t dev, struct uio *uio, int ioflag));
 typedef int d_poll_t __P((dev_t dev, int events, struct proc *p));
+typedef int d_kqfilter_t __P((dev_t dev, struct knote *kn));
 typedef int d_mmap_t __P((dev_t dev, vm_offset_t offset, int nprot));
 
 typedef int l_open_t __P((dev_t dev, struct tty *tp));
@@ -151,10 +153,11 @@ typedef void devfs_remove_t __P((dev_t dev));
 /*
  * Flags for d_flags.
  */
-#define	D_MEMDISK	0x10000		/* memory type disk */
-#define	D_NAGGED	0x20000		/* nagged about missing make_dev() */
-#define	D_CANFREE	0x40000		/* can free blocks */
-#define	D_TRACKCLOSE	0x80000		/* track all closes */
+#define	D_MEMDISK	0x00010000	/* memory type disk */
+#define	D_NAGGED	0x00020000	/* nagged about missing make_dev() */
+#define	D_CANFREE	0x00040000	/* can free blocks */
+#define	D_TRACKCLOSE	0x00080000	/* track all closes */
+#define	D_KQFILTER	0x00200000	/* has kqfilter entry */
 
 /*
  * Character device switch table
@@ -174,6 +177,8 @@ struct cdevsw {
 	d_psize_t	*d_psize;
 	u_int		d_flags;
 	int		d_bmaj;
+	/* additions below are not binary compatible with 4.2 and below */
+	d_kqfilter_t	*d_kqfilter;
 };
 
 /*
@@ -221,6 +226,7 @@ d_read_t	noread;
 d_write_t	nowrite;
 d_ioctl_t	noioctl;
 d_mmap_t	nommap;
+d_kqfilter_t	nokqfilter;
 #define	nostrategy	((d_strategy_t *)NULL)
 #define	nopoll	seltrue
 
diff --git a/sys/sys/event.h b/sys/sys/event.h
index 6182bccd0926..de4eefe9869a 100644
--- a/sys/sys/event.h
+++ b/sys/sys/event.h
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 1999,2000 Jonathan Lemon <jlemon@FreeBSD.org>
+ * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -38,6 +38,15 @@
 
 #define EVFILT_SYSCOUNT		6
 
+#define EV_SET(kevp, a, b, c, d, e, f) do {	\
+	(kevp)->ident = (a);			\
+	(kevp)->filter = (b);			\
+	(kevp)->flags = (c);			\
+	(kevp)->fflags = (d);			\
+	(kevp)->data = (e);			\
+	(kevp)->udata = (f);			\
+} while(0)
+
 struct kevent {
 	uintptr_t	ident;		/* identifier for this event */
 	short		filter;		/* filter for event */
@@ -65,6 +74,11 @@ struct kevent {
 #define EV_ERROR	0x4000		/* error, data contains errno */
 
 /*
+ * data/hint flags for EVFILT_{READ|WRITE}, shared with userspace
+ */
+#define NOTE_LOWAT	0x0001			/* low water mark */
+
+/*
  * data/hint flags for EVFILT_VNODE, shared with userspace
  */
 #define	NOTE_DELETE	0x0001			/* vnode was removed */
@@ -73,6 +87,7 @@ struct kevent {
 #define	NOTE_ATTRIB	0x0008			/* attributes changed */
 #define	NOTE_LINK	0x0010			/* link count changed */
 #define	NOTE_RENAME	0x0020			/* vnode was renamed */
+#define	NOTE_REVOKE	0x0040			/* vnode access was revoked */
 
 /*
  * data/hint flags for EVFILT_PROC, shared with userspace
@@ -127,6 +142,7 @@ struct knote {
 		struct		proc *p_proc;	/* proc pointer */
 	} kn_ptr;
 	struct			filterops *kn_fop;
+	caddr_t			kn_hook;
 #define KN_ACTIVE	0x01			/* event has been triggered */
 #define KN_QUEUED	0x02			/* event is on queue */
 #define KN_DISABLED	0x04			/* event is disabled */
diff --git a/sys/sys/file.h b/sys/sys/file.h
index b3a092010594..41a7ed8a4aa3 100644
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -48,6 +48,7 @@
 struct stat;
 struct proc;
 struct uio;
+struct knote;
 
 /*
  * Kernel descriptor table.
@@ -77,6 +78,8 @@ struct file {
 					    caddr_t data, struct proc *p));
 		int	(*fo_poll)	__P((struct file *fp, int events,
 					    struct ucred *cred, struct proc *p));
+		int	(*fo_kqfilter)	__P((struct file *fp,
+					    struct knote *kn));
 		int	(*fo_stat)	__P((struct file *fp, struct stat *sb,
 					    struct proc *p));
 		int	(*fo_close)	__P((struct file *fp, struct proc *p));
@@ -128,6 +131,7 @@ static __inline int fo_poll __P((struct file *fp, int events,
 static __inline int fo_stat __P((struct file *fp, struct stat *sb,
     struct proc *p));
 static __inline int fo_close __P((struct file *fp, struct proc *p));
+static __inline int fo_kqfilter __P((struct file *fp, struct knote *kn));
 
 static __inline int
 fo_read(fp, uio, cred, flags, p)
@@ -214,6 +218,15 @@ fo_close(fp, p)
 	return ((*fp->f_ops->fo_close)(fp, p));
 }
 
+static __inline int
+fo_kqfilter(fp, kn)
+	struct file *fp;
+	struct knote *kn;
+{
+
+	return ((*fp->f_ops->fo_kqfilter)(fp, kn));
+}
+
 #endif /* _KERNEL */
 
 #endif /* !SYS_FILE_H */
diff --git a/sys/sys/socketvar.h b/sys/sys/socketvar.h
index 95960c9c7e78..1043493b4dc5 100644
--- a/sys/sys/socketvar.h
+++ b/sys/sys/socketvar.h
@@ -306,6 +306,7 @@ struct sockaddr;
 struct stat;
 struct ucred;
 struct uio;
+struct knote;
 
 /*
  * File operations on sockets.
@@ -320,6 +321,7 @@ int	soo_ioctl __P((struct file *fp, u_long cmd, caddr_t data,
 int	soo_poll __P((struct file *fp, int events, struct ucred *cred,
 	    struct proc *p));
 int	soo_stat __P((struct file *fp, struct stat *ub, struct proc *p));
+int	sokqfilter __P((struct file *fp, struct knote *kn));
 
 /*
  * From uipc_socket and friends
diff --git a/sys/sys/tty.h b/sys/sys/tty.h
index 46b11ea4edc0..6121ed6a245e 100644
--- a/sys/sys/tty.h
+++ b/sys/sys/tty.h
@@ -263,6 +263,7 @@ struct tty *ttymalloc __P((struct tty *tp));
 int	 ttymodem __P((struct tty *tp, int flag));
 int	 ttyopen __P((dev_t device, struct tty *tp));
 int	 ttypoll __P((dev_t dev, int events, struct proc *p));
+int	 ttykqfilter __P((dev_t dev, struct knote *kn));
 int	 ttyread __P((dev_t dev, struct uio *uio, int flag));
 void	 ttyregister __P((struct tty *tp));
 int	 ttysleep __P((struct tty *tp, void *chan, int pri, char *wmesg,
diff --git a/sys/ufs/ufs/ufs_vnops.c b/sys/ufs/ufs/ufs_vnops.c
index 8cb433558a46..5084f061d77e 100644
--- a/sys/ufs/ufs/ufs_vnops.c
+++ b/sys/ufs/ufs/ufs_vnops.c
@@ -59,6 +59,8 @@
 #include <sys/event.h>
 #include <sys/conf.h>
 
+#include <sys/file.h>		/* XXX */
+
 #include <vm/vm.h>
 #include <vm/vm_extern.h>
 
@@ -101,6 +103,10 @@ static int ufsfifo_write __P((struct vop_write_args *));
 static int ufsspec_close __P((struct vop_close_args *));
 static int ufsspec_read __P((struct vop_read_args *));
 static int ufsspec_write __P((struct vop_write_args *));
+static int filt_ufsread __P((struct knote *kn, long hint));
+static int filt_ufsvnode __P((struct knote *kn, long hint));
+static void filt_ufsdetach __P((struct knote *kn));
+static int ufs_kqfilter __P((struct vop_kqfilter_args *ap));
 
 union _qcvt {
 	int64_t qcvt;
@@ -2189,6 +2195,85 @@ ufs_missingop(ap)
 	return (EOPNOTSUPP);
 }
 
+static struct filterops ufsread_filtops = 
+	{ 1, NULL, filt_ufsdetach, filt_ufsread };
+static struct filterops ufsvnode_filtops = 
+	{ 1, NULL, filt_ufsdetach, filt_ufsvnode };
+
+static int
+ufs_kqfilter(ap)
+	struct vop_kqfilter_args /* {
+		struct vnode *a_vp;
+		struct knote *a_kn;
+	} */ *ap;
+{
+	struct vnode *vp = ap->a_vp;
+	struct knote *kn = ap->a_kn;
+
+	switch (kn->kn_filter) {
+	case EVFILT_READ:
+		kn->kn_fop = &ufsread_filtops;
+		break;
+	case EVFILT_VNODE:
+		kn->kn_fop = &ufsvnode_filtops;
+		break;
+	default:
+		return (1);
+	}
+
+	kn->kn_hook = (caddr_t)vp;
+
+	simple_lock(&vp->v_pollinfo.vpi_lock);
+	SLIST_INSERT_HEAD(&vp->v_pollinfo.vpi_selinfo.si_note, kn, kn_selnext);
+	simple_unlock(&vp->v_pollinfo.vpi_lock);
+
+	return (0);
+}
+
+static void
+filt_ufsdetach(struct knote *kn)
+{
+	struct vnode *vp = (struct vnode *)kn->kn_hook;
+
+	simple_lock(&vp->v_pollinfo.vpi_lock);
+	SLIST_REMOVE(&vp->v_pollinfo.vpi_selinfo.si_note,
+	    kn, knote, kn_selnext);
+	simple_unlock(&vp->v_pollinfo.vpi_lock);
+}
+
+/*ARGSUSED*/
+static int
+filt_ufsread(struct knote *kn, long hint)
+{
+	struct vnode *vp = (struct vnode *)kn->kn_hook;
+	struct inode *ip = VTOI(vp);
+
+	/*
+	 * filesystem is gone, so set the EOF flag and schedule 
+	 * the knote for deletion.
+	 */
+	if (hint == NOTE_REVOKE) {
+		kn->kn_flags |= (EV_EOF | EV_ONESHOT);
+		return (1);
+	}
+
+        kn->kn_data = ip->i_size - kn->kn_fp->f_offset;
+        return (kn->kn_data != 0);
+}
+
+static int
+filt_ufsvnode(struct knote *kn, long hint)
+{
+
+	if (kn->kn_sfflags & hint)
+		kn->kn_fflags |= hint;
+	if (hint == NOTE_REVOKE) {
+		kn->kn_flags |= EV_EOF;
+		return (1);
+	}
+	return (kn->kn_fflags != 0);
+}
+
 /* Global vfs data structures for ufs. */
 static vop_t **ufs_vnodeop_p;
 static struct vnodeopv_entry_desc ufs_vnodeop_entries[] = {
@@ -2215,6 +2300,7 @@ static struct vnodeopv_entry_desc ufs_vnodeop_entries[] = {
 	{ &vop_open_desc,		(vop_t *) ufs_open },
 	{ &vop_pathconf_desc,		(vop_t *) ufs_pathconf },
 	{ &vop_poll_desc,		(vop_t *) vop_stdpoll },
+	{ &vop_kqfilter_desc,		(vop_t *) ufs_kqfilter },
 	{ &vop_print_desc,		(vop_t *) ufs_print },
 	{ &vop_readdir_desc,		(vop_t *) ufs_readdir },
 	{ &vop_readlink_desc,		(vop_t *) ufs_readlink },