Integrate the new MPSAFE TTY layer to the FreeBSD operating system.

The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:

- Improved driver model:

  The old TTY layer has a driver model that is not abstract enough to
  make it friendly to use. A good example is the output path, where the
  device drivers directly access the output buffers. This means that an
  in-kernel PPP implementation must always convert network buffers into
  TTY buffers.

  If a PPP implementation would be built on top of the new TTY layer
  (still needs a hooks layer, though), it would allow the PPP
  implementation to directly hand the data to the TTY driver.

- Improved hotplugging:

  With the old TTY layer, it isn't entirely safe to destroy TTY's from
  the system. This implementation has a two-step destructing design,
  where the driver first abandons the TTY. After all threads have left
  the TTY, the TTY layer calls a routine in the driver, which can be
  used to free resources (unit numbers, etc).

  The pts(4) driver also implements this feature, which means
  posix_openpt() will now return PTY's that are created on the fly.

- Improved performance:

  One of the major improvements is the per-TTY mutex, which is expected
  to improve scalability when compared to the old Giant locking.
  Another change is the unbuffered copying to userspace, which is both
  used on TTY device nodes and PTY masters.

Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.

Obtained from:		//depot/projects/mpsafetty/...
Approved by:		philip (ex-mentor)
Discussed:		on the lists, at BSDCan, at the DevSummit
Sponsored by:		Snow B.V., the Netherlands
dcons(4) fixed by:	kan

2 files changed, 49 insertions, 346 deletions

diff --git a/sys/dev/dcons/dcons.h b/sys/dev/dcons/dcons.h
index 49ef869..e613f5b 100644
--- a/sys/dev/dcons/dcons.h
+++ b/sys/dev/dcons/dcons.h
@@ -98,7 +98,7 @@ struct dcons_softc {
         int brk_state;
 #define DC_GDB  1
         int flags;
-	void *dev;
+	void *tty;
 };
 
 int	dcons_checkc(struct dcons_softc *);
diff --git a/sys/dev/dcons/dcons_os.c b/sys/dev/dcons/dcons_os.c
index a43cd28..aad9637 100644
--- a/sys/dev/dcons/dcons_os.c
+++ b/sys/dev/dcons/dcons_os.c
@@ -1,7 +1,7 @@
 /*-
  * Copyright (C) 2003,2004
  * 	Hidetoshi Shimokawa. All rights reserved.
- * 
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -18,7 +18,7 @@
  * 4. Neither the name of the author nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
- * 
+ *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
@@ -30,15 +30,13 @@
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
- * 
+ *
  * $FreeBSD$
  */
 
 #include <sys/param.h>
-#if __FreeBSD_version >= 502122
 #include <sys/kdb.h>
 #include <gdb/gdb.h>
-#endif
 #include <sys/kernel.h>
 #include <sys/module.h>
 #include <sys/systm.h>
@@ -54,13 +52,8 @@
 
 #include <machine/bus.h>
 
-#ifdef __DragonFly__
-#include "dcons.h"
-#include "dcons_os.h"
-#else
 #include <dev/dcons/dcons.h>
 #include <dev/dcons/dcons_os.h>
-#endif
 
 #include <ddb/ddb.h>
 #include <sys/reboot.h>
@@ -90,53 +83,6 @@
 #define DCONS_FORCE_CONSOLE	0	/* Mostly for FreeBSD-4/DragonFly */
 #endif
 
-#ifndef DCONS_FORCE_GDB
-#define DCONS_FORCE_GDB	1
-#endif
-
-#if __FreeBSD_version >= 500101
-#define CONS_NODEV	1
-#if __FreeBSD_version < 502122
-static struct consdev gdbconsdev;
-#endif
-#endif
-
-static d_open_t		dcons_open;
-static d_close_t	dcons_close;
-#if defined(__DragonFly__) || __FreeBSD_version < 500104
-static d_ioctl_t	dcons_ioctl;
-#endif
-
-static struct cdevsw dcons_cdevsw = {
-#ifdef __DragonFly__
-#define CDEV_MAJOR      184
-	"dcons", CDEV_MAJOR, D_TTY, NULL, 0,
-	dcons_open, dcons_close, ttyread, ttywrite, dcons_ioctl,
-	ttypoll, nommap, nostrategy, nodump, nopsize,
-#elif __FreeBSD_version >= 500104
-	.d_version =	D_VERSION,
-	.d_open =	dcons_open,
-	.d_close =	dcons_close,
-	.d_name =	"dcons",
-	.d_flags =	D_TTY | D_NEEDGIANT,
-#else
-#define CDEV_MAJOR      184
-	/* open */	dcons_open,
-	/* close */	dcons_close,
-	/* read */	ttyread,
-	/* write */	ttywrite,
-	/* ioctl */	dcons_ioctl,
-	/* poll */	ttypoll,
-	/* mmap */	nommap,
-	/* strategy */	nostrategy,
-	/* name */	"dcons",
-	/* major */	CDEV_MAJOR,
-	/* dump */	nodump,
-	/* psize */	nopsize,
-	/* flags */	D_TTY,
-#endif
-};
-
 #ifndef KLD_MODULE
 static char bssbuf[DCONS_BUF_SIZE];	/* buf in bss */
 #endif
@@ -156,20 +102,6 @@ static int drv_init = 0;
 static struct callout dcons_callout;
 struct dcons_buf *dcons_buf;		/* for local dconschat */
 
-#ifdef __DragonFly__
-#define DEV	dev_t
-#define THREAD	d_thread_t
-#elif __FreeBSD_version < 500000
-#define DEV	dev_t
-#define THREAD	struct proc
-#else
-#define DEV	struct cdev *
-#define THREAD	struct thread
-#endif
-
-
-static void	dcons_tty_start(struct tty *);
-static int	dcons_tty_param(struct tty *, struct termios *);
 static void	dcons_timeout(void *);
 static int	dcons_drv_init(int);
 
@@ -181,12 +113,12 @@ static cn_putc_t	dcons_cnputc;
 
 CONSOLE_DRIVER(dcons);
 
-#if defined(GDB) && (__FreeBSD_version >= 502122)
-static gdb_probe_f dcons_dbg_probe;
-static gdb_init_f dcons_dbg_init;
-static gdb_term_f dcons_dbg_term;
-static gdb_getc_f dcons_dbg_getc;
-static gdb_putc_f dcons_dbg_putc;
+#if defined(GDB)
+static gdb_probe_f	dcons_dbg_probe;
+static gdb_init_f	dcons_dbg_init;
+static gdb_term_f	dcons_dbg_term;
+static gdb_getc_f	dcons_dbg_getc;
+static gdb_putc_f	dcons_dbg_putc;
 
 GDB_DBGPORT(dcons, dcons_dbg_probe, dcons_dbg_init, dcons_dbg_term,
     dcons_dbg_getc, dcons_dbg_putc);
@@ -194,21 +126,25 @@ GDB_DBGPORT(dcons, dcons_dbg_probe, dcons_dbg_init, dcons_dbg_term,
 extern struct gdb_dbgport *gdb_cur;
 #endif
 
+static tsw_outwakeup_t dcons_outwakeup;
+
+static struct ttydevsw dcons_ttydevsw = {
+	.tsw_flags      = TF_NOPREFIX,
+	.tsw_outwakeup  = dcons_outwakeup,
+};
+
 #if (defined(GDB) || defined(DDB)) && defined(ALT_BREAK_TO_DEBUGGER)
 static int
 dcons_check_break(struct dcons_softc *dc, int c)
 {
-#if __FreeBSD_version >= 502122
 	int kdb_brk;
-#endif
+
 	if (c < 0)
 		return (c);
 
-#if __FreeBSD_version >= 502122
 	if ((kdb_brk = kdb_alt_break(c, &dc->brk_state)) != 0) {
 		switch (kdb_brk) {
 		case KDB_REQ_DEBUGGER:
-		
 			if ((dc->flags & DC_GDB) != 0) {
 #ifdef GDB
 				if (gdb_cur == &dcons_gdb_dbgport) {
@@ -229,27 +165,6 @@ dcons_check_break(struct dcons_softc *dc, int c)
 			break;
 		}
 	}
-#else
-	switch (dc->brk_state) {
-	case STATE1:
-		if (c == KEY_TILDE)
-			dc->brk_state = STATE2;
-		else
-			dc->brk_state = STATE0;
-		break;
-	case STATE2:
-		dc->brk_state = STATE0;
-		if (c == KEY_CTRLB) {
-#if DCONS_FORCE_GDB
-			if (dc->flags & DC_GDB)
-				boothowto |= RB_GDB;
-#endif
-			breakpoint();
-		}
-	}
-	if (c == KEY_CR)
-		dc->brk_state = STATE1;
-#endif
 	return (c);
 }
 #else
@@ -263,7 +178,7 @@ dcons_os_checkc_nopoll(struct dcons_softc *dc)
 
 	if (dg.dma_tag != NULL)
 		bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_POSTREAD);
-  
+
 	c = dcons_check_break(dc, dcons_checkc(dc));
 
 	if (dg.dma_tag != NULL)
@@ -279,18 +194,6 @@ dcons_os_checkc(struct dcons_softc *dc)
 	return (dcons_os_checkc_nopoll(dc));
 }
 
-#if defined(GDB) || !defined(CONS_NODEV)
-static int
-dcons_os_getc(struct dcons_softc *dc)
-{
-	int c;
-
-	while ((c = dcons_os_checkc(dc)) == -1);
-
-	return (c & 0xff);
-} 
-#endif
-
 static void
 dcons_os_putc(struct dcons_softc *dc, int c)
 {
@@ -302,122 +205,17 @@ dcons_os_putc(struct dcons_softc *dc, int c)
 	if (dg.dma_tag != NULL)
 		bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_PREWRITE);
 }
-static int
-dcons_open(DEV dev, int flag, int mode, THREAD *td)
-{
-	struct tty *tp;
-	int unit, error, s;
-
-	unit = minor(dev);
-	if (unit != 0)
-		return (ENXIO);
-
-	tp = dev->si_tty;
-	tp->t_oproc = dcons_tty_start;
-	tp->t_param = dcons_tty_param;
-	tp->t_stop = nottystop;
-	tp->t_dev = dev;
-
-	error = 0;
-
-	s = spltty();
-	if ((tp->t_state & TS_ISOPEN) == 0) {
-		tp->t_state |= TS_CARR_ON;
-		ttyconsolemode(tp, 0);
-	} else if ((tp->t_state & TS_XCLUDE) &&
-	    priv_check(td, PRIV_TTY_EXCLUSIVE)) {
-		splx(s);
-		return (EBUSY);
-	}
-	splx(s);
-
-#if __FreeBSD_version < 502113
-	error = (*linesw[tp->t_line].l_open)(dev, tp);
-#else
-	error = ttyld_open(tp, dev);
-#endif
-
-	return (error);
-}
-
-static int
-dcons_close(DEV dev, int flag, int mode, THREAD *td)
-{
-	int	unit;
-	struct	tty *tp;
-
-	unit = minor(dev);
-	if (unit != 0)
-		return (ENXIO);
-
-	tp = dev->si_tty;
-	if (tp->t_state & TS_ISOPEN) {
-#if __FreeBSD_version < 502113
-		(*linesw[tp->t_line].l_close)(tp, flag);
-		ttyclose(tp);
-#else
-		ttyld_close(tp, flag);
-		tty_close(tp);
-#endif
-	}
-
-	return (0);
-}
-
-#if defined(__DragonFly__) || __FreeBSD_version < 500104
-static int
-dcons_ioctl(DEV dev, u_long cmd, caddr_t data, int flag, THREAD *td)
-{
-	int	unit;
-	struct	tty *tp;
-	int	error;
-
-	unit = minor(dev);
-	if (unit != 0)
-		return (ENXIO);
-
-	tp = dev->si_tty;
-	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, td);
-	if (error != ENOIOCTL)
-		return (error);
-
-	error = ttioctl(tp, cmd, data, flag);
-	if (error != ENOIOCTL)
-		return (error);
-
-	return (ENOTTY);
-}
-#endif
-
-static int
-dcons_tty_param(struct tty *tp, struct termios *t)
-{
-	tp->t_ispeed = t->c_ispeed;
-	tp->t_ospeed = t->c_ospeed;
-	tp->t_cflag = t->c_cflag;
-	return 0;
-}
 
 static void
-dcons_tty_start(struct tty *tp)
+dcons_outwakeup(struct tty *tp)
 {
 	struct dcons_softc *dc;
-	int s;
-
-	dc = (struct dcons_softc *)tp->t_dev->si_drv1;
-	s = spltty();
-	if (tp->t_state & (TS_TIMEOUT | TS_TTSTOP)) {
-		ttwwakeup(tp);
-		return;
-	}
+	char ch;
 
-	tp->t_state |= TS_BUSY;
-	while (tp->t_outq.c_cc != 0)
-		dcons_os_putc(dc, getc(&tp->t_outq));
-	tp->t_state &= ~TS_BUSY;
+	dc = tty_softc(tp);
 
-	ttwwakeup(tp);
-	splx(s);
+	while (ttydisc_getc(tp, &ch, sizeof ch) != 0)
+		dcons_os_putc(dc, ch);
 }
 
 static void
@@ -429,14 +227,13 @@ dcons_timeout(void *v)
 
 	for (i = 0; i < DCONS_NPORT; i ++) {
 		dc = &sc[i];
-		tp = ((DEV)dc->dev)->si_tty;
+		tp = dc->tty;
+
+		tty_lock(tp);
 		while ((c = dcons_os_checkc_nopoll(dc)) != -1)
-			if (tp->t_state & TS_ISOPEN)
-#if __FreeBSD_version < 502113
-				(*linesw[tp->t_line].l_rint)(c, tp);
-#else
-				ttyld_rint(tp, c);
-#endif
+			ttydisc_rint(tp, c, 0);
+		ttydisc_rint_done(tp);
+		tty_unlock(tp);
 	}
 	polltime = hz / poll_hz;
 	if (polltime < 1)
@@ -447,14 +244,7 @@ dcons_timeout(void *v)
 static void
 dcons_cnprobe(struct consdev *cp)
 {
-#ifdef __DragonFly__
-	cp->cn_dev = make_dev(&dcons_cdevsw, DCONS_CON,
-	    UID_ROOT, GID_WHEEL, 0600, "dcons");
-#elif __FreeBSD_version >= 501109
 	sprintf(cp->cn_name, "dcons");
-#else
-	cp->cn_dev = makedev(CDEV_MAJOR, DCONS_CON);
-#endif
 #if DCONS_FORCE_CONSOLE
 	cp->cn_pri = CN_REMOTE;
 #else
@@ -466,12 +256,7 @@ static void
 dcons_cninit(struct consdev *cp)
 {
 	dcons_drv_init(0);
-#if CONS_NODEV
-	cp->cn_arg
-#else
-	cp->cn_dev->si_drv1
-#endif
-		= (void *)&sc[DCONS_CON]; /* share port0 with unit0 */
+	cp->cn_arg = (void *)&sc[DCONS_CON]; /* share port0 with unit0 */
 }
 
 static void
@@ -479,39 +264,19 @@ dcons_cnterm(struct consdev *cp)
 {
 }
 
-#if CONS_NODEV
 static int
 dcons_cngetc(struct consdev *cp)
 {
 	struct dcons_softc *dc = (struct dcons_softc *)cp->cn_arg;
 	return (dcons_os_checkc(dc));
 }
+
 static void
 dcons_cnputc(struct consdev *cp, int c)
 {
 	struct dcons_softc *dc = (struct dcons_softc *)cp->cn_arg;
 	dcons_os_putc(dc, c);
 }
-#else
-static int
-dcons_cngetc(DEV dev)
-{
-	struct dcons_softc *dc = (struct dcons_softc *)dev->si_drv1;
-	return (dcons_os_getc(dc));
-}
-static int
-dcons_cncheckc(DEV dev)
-{
-	struct dcons_softc *dc = (struct dcons_softc *)dev->si_drv1;
-	return (dcons_os_checkc(dc));
-}
-static void
-dcons_cnputc(DEV dev, int c)
-{
-	struct dcons_softc *dc = (struct dcons_softc *)dev->si_drv1;
-	dcons_os_putc(dc, c);
-}
-#endif
 
 static int
 dcons_drv_init(int stage)
@@ -577,24 +342,6 @@ dcons_drv_init(int stage)
 ok:
 	dcons_buf = dg.buf;
 
-#if __FreeBSD_version < 502122
-#if defined(DDB) && DCONS_FORCE_GDB
-#if CONS_NODEV
-	gdbconsdev.cn_arg = (void *)&sc[DCONS_GDB];
-#if __FreeBSD_version >= 501109
-	sprintf(gdbconsdev.cn_name, "dgdb");
-#endif
-	gdb_arg = &gdbconsdev;
-#elif defined(__DragonFly__)
-	gdbdev = make_dev(&dcons_cdevsw, DCONS_GDB,
-	    UID_ROOT, GID_WHEEL, 0600, "dgdb");
-#else
-	gdbdev = makedev(CDEV_MAJOR, DCONS_GDB);
-#endif
-	gdb_getc = dcons_cngetc;
-	gdb_putc = dcons_cnputc;
-#endif
-#endif
 	drv_init = 1;
 
 	return 0;
@@ -606,23 +353,12 @@ dcons_attach_port(int port, char *name, int flags)
 {
 	struct dcons_softc *dc;
 	struct tty *tp;
-	DEV dev;
 
 	dc = &sc[port];
+	tp = tty_alloc(&dcons_ttydevsw, dc, NULL);
 	dc->flags = flags;
-	dev = make_dev(&dcons_cdevsw, port,
-			UID_ROOT, GID_WHEEL, 0600, name);
-	dc->dev = (void *)dev;
-	tp = ttyalloc();
-
-	dev->si_drv1 = (void *)dc;
-	dev->si_tty = tp;
-
-	tp->t_oproc = dcons_tty_start;
-	tp->t_param = dcons_tty_param;
-	tp->t_stop = nottystop;
-	tp->t_dev = dc->dev;
-
+	dc->tty   = tp;
+	tty_makedev(tp, NULL, "%s", name);
 	return(0);
 }
 
@@ -631,16 +367,9 @@ dcons_attach(void)
 {
 	int polltime;
 
-#ifdef __DragonFly__
-	cdevsw_add(&dcons_cdevsw, -1, 0);
-#endif
 	dcons_attach_port(DCONS_CON, "dcons", 0);
 	dcons_attach_port(DCONS_GDB, "dgdb", DC_GDB);
-#if __FreeBSD_version < 500000
-	callout_init(&dcons_callout);
-#else
 	callout_init(&dcons_callout, 0);
-#endif
 	polltime = hz / poll_hz;
 	if (polltime < 1)
 		polltime = 1;
@@ -655,37 +384,14 @@ dcons_detach(int port)
 	struct dcons_softc *dc;
 
 	dc = &sc[port];
+	tp = dc->tty;
 
-	tp = ((DEV)dc->dev)->si_tty;
-
-	if (tp->t_state & TS_ISOPEN) {
-		printf("dcons: still opened\n");
-#if __FreeBSD_version < 502113
-		(*linesw[tp->t_line].l_close)(tp, 0);
-		tp->t_gen++;
-		ttyclose(tp);
-		ttwakeup(tp);
-		ttwwakeup(tp);
-#else
-		ttyld_close(tp, 0);
-		tty_close(tp);
-#endif
-	}
-	/* XXX
-	 * must wait until all device are closed.
-	 */
-#ifdef __DragonFly__
-	tsleep((void *)dc, 0, "dcodtc", hz/4);
-#else
-	tsleep((void *)dc, PWAIT, "dcodtc", hz/4);
-#endif
-	destroy_dev(dc->dev);
+	tty_lock(tp);
+	tty_rel_gone(tp);
 
 	return(0);
 }
 
-
-/* cnXXX works only for FreeBSD-5 */
 static int
 dcons_modevent(module_t mode, int type, void *data)
 {
@@ -695,29 +401,16 @@ dcons_modevent(module_t mode, int type, void *data)
 	case MOD_LOAD:
 		ret = dcons_drv_init(1);
 		dcons_attach();
-#if __FreeBSD_version >= 500000
 		if (ret == 0) {
 			dcons_cnprobe(&dcons_consdev);
 			dcons_cninit(&dcons_consdev);
 			cnadd(&dcons_consdev);
 		}
-#endif
 		break;
 	case MOD_UNLOAD:
 		printf("dcons: unload\n");
 		callout_stop(&dcons_callout);
-#if __FreeBSD_version < 502122
-#if defined(DDB) && DCONS_FORCE_GDB
-#if CONS_NODEV
-		gdb_arg = NULL;
-#else
-		gdbdev = NULL;
-#endif
-#endif
-#endif
-#if __FreeBSD_version >= 500000
 		cnremove(&dcons_consdev);
-#endif
 		dcons_detach(DCONS_CON);
 		dcons_detach(DCONS_GDB);
 		dg.buf->magic = 0;
@@ -737,10 +430,20 @@ dcons_modevent(module_t mode, int type, void *data)
 	return(err);
 }
 
-#if defined(GDB) && (__FreeBSD_version >= 502122)
+#if defined(GDB)
 /* Debugger interface */
 
 static int
+dcons_os_getc(struct dcons_softc *dc)
+{
+	int c;
+
+	while ((c = dcons_os_checkc(dc)) == -1);
+
+	return (c & 0xff);
+}
+
+static int
 dcons_dbg_probe(void)
 {
 	int dcons_gdb;