2.2.27-pre2 tty/ldisc fixes

diff -urN linux-2.2.26.orig/drivers/char/cyclades.c linux-2.2.26/drivers/char/cyclades.c
@@ -1019,10 +1019,7 @@
 	wake_up_interruptible(&info->delta_msr_wait);
     }
     if (test_and_clear_bit(Cy_EVENT_WRITE_WAKEUP, &info->event)) {
-        if((tty->flags & (1<< TTY_DO_WRITE_WAKEUP))
-        && tty->ldisc.write_wakeup){
-            (tty->ldisc.write_wakeup)(tty);
-        }
+	tty_wakeup(tty);
         wake_up_interruptible(&tty->write_wait);
 	wake_up_interruptible(&tty->poll_wait);
     }

@@ -2821,6 +2818,7 @@
 cy_close(struct tty_struct *tty, struct file *filp)
 {
   struct cyclades_port *info = (struct cyclades_port *)tty->driver_data;
+  struct tty_ldisc *ld;
   unsigned long flags;
 
 #ifdef CY_DEBUG_OTHER

@@ -2938,8 +2936,12 @@
     shutdown(info);
     if (tty->driver.flush_buffer)
         tty->driver.flush_buffer(tty);
-    if (tty->ldisc.flush_buffer)
-        tty->ldisc.flush_buffer(tty);
+    ld = tty_ldisc_ref(tty);
+    if (ld) {
+	    if (ld->flush_buffer)
+	    ld->flush_buffer(tty);
+	    tty_ldisc_deref(ld);
+    }
     CY_LOCK(info, flags);
 
     tty->closing = 0;

@@ -4701,11 +4703,9 @@
 	}
 	CY_UNLOCK(info, flags);
     }
+    tty_wakeup(tty);
     wake_up_interruptible(&tty->write_wait);
     wake_up_interruptible(&tty->poll_wait);
-    if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP))
-	&& tty->ldisc.write_wakeup)
-	    (tty->ldisc.write_wakeup)(tty);
 } /* cy_flush_buffer */
 
 

diff -urN linux-2.2.26.orig/drivers/char/dz.c linux-2.2.26/drivers/char/dz.c
@@ -1084,10 +1084,10 @@
   info->event = 0;
   info->tty = 0;
 
-  if (tty->ldisc.num != ldiscs[N_TTY].num) {
+  if (tty->ldisc.num != N_TTY) {
     if (tty->ldisc.close)
       (tty->ldisc.close)(tty);
-    tty->ldisc = ldiscs[N_TTY];
+    tty->ldisc = *(tty_ldisc_get(N_TTY));
     tty->termios->c_line = N_TTY;
     if (tty->ldisc.open)
       (tty->ldisc.open)(tty);

diff -urN linux-2.2.26.orig/drivers/char/epca.c linux-2.2.26/drivers/char/epca.c
@@ -572,7 +572,8 @@
 
 	if ((ch = verifyChannel(tty)) != NULL) 
 	{ /* Begin if ch != NULL */
-
+		struct tty_ldisc *ld;	
+	
 		save_flags(flags);
 		cli();
 

@@ -633,8 +634,12 @@
 		if (tty->driver.flush_buffer)
 			tty->driver.flush_buffer(tty);
 
-		if (tty->ldisc.flush_buffer)
-			tty->ldisc.flush_buffer(tty);
+		ld = tty_ldisc_ref(tty);
+			if (ld != NULL) {
+				if(ld->flush_buffer)
+				    ld->flush_buffer(tty);
+			tty_ldisc_deref(ld);
+			}
 
 		shutdown(ch);
 		tty->closing = 0;

@@ -737,12 +742,20 @@
 	{ /* Begin if ch != NULL */
 
 		unsigned long flags;
-
+		struct tty_ldisc *ld;
+		
 		save_flags(flags);
 		cli();
 		if (tty->driver.flush_buffer)
 			tty->driver.flush_buffer(tty);
 
+		ld = tty_ldisc_ref(tty);
+		if (ld != NULL) {
+			if (ld->flush_buffer)
+				ld->flush_buffer(tty);
+			tty_ldisc_deref(ld);
+		}
+		
 		if (tty->ldisc.flush_buffer)
 			tty->ldisc.flush_buffer(tty);
 

@@ -1227,9 +1240,8 @@
 
 	wake_up_interruptible(&tty->write_wait);
 	wake_up_interruptible(&tty->poll_wait);
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup)(tty);
-
+	tty_wakeup(tty);
+	
 } /* End pc_flush_buffer */
 
 /* ------------------ Begin pc_flush_chars  ---------------------- */

@@ -2443,9 +2455,7 @@
 				{ /* Begin if LOWWAIT */
 
 					ch->statusflags &= ~LOWWAIT;
-					if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-						  tty->ldisc.write_wakeup)
-						(tty->ldisc.write_wakeup)(tty);
+					tty_wakeup(tty);
 					wake_up_interruptible(&tty->write_wait);
 					wake_up_interruptible(&tty->poll_wait);
 				} /* End if LOWWAIT */

@@ -2462,9 +2472,7 @@
 				{ /* Begin if EMPTYWAIT */
 
 					ch->statusflags &= ~EMPTYWAIT;
-					if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-						  tty->ldisc.write_wakeup)
-						(tty->ldisc.write_wakeup)(tty);
+					tty_wakeup(tty);
 
 					wake_up_interruptible(&tty->write_wait);
 					wake_up_interruptible(&tty->poll_wait);

@@ -3327,6 +3335,7 @@
 				tty_wait_until_sent(tty, 0);
 			}
 			else 
+			/* ldisc lock already held in ioctl */
 			{
 				if (tty->ldisc.flush_buffer)
 					tty->ldisc.flush_buffer(tty);

diff -urN linux-2.2.26.orig/drivers/char/generic_serial.c linux-2.2.26/drivers/char/generic_serial.c
@@ -453,9 +453,7 @@
 	restore_flags(flags);
 
 	wake_up_interruptible(&tty->write_wait);
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-	    tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup)(tty);
+	tty_wakeup(tty);
 	func_exit ();
 }
 

@@ -595,9 +593,7 @@
 	if (!tty) return;
 
 	if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &port->event)) {
-		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-		    tty->ldisc.write_wakeup)
-			(tty->ldisc.write_wakeup)(tty);
+		tty_wakeup(tty);
 		wake_up_interruptible(&tty->write_wait);
 	}
 	func_exit ();

@@ -740,8 +736,9 @@
 {
 	unsigned long flags;
 	struct gs_port *port;
-
-	func_enter ();
+	struct tty_ldisc *ld;
+ 
+	func_enter();
 
 	if (!tty) return;
 

@@ -818,8 +815,12 @@
 
 	if (tty->driver.flush_buffer)
 		tty->driver.flush_buffer(tty);
-	if (tty->ldisc.flush_buffer)
-		tty->ldisc.flush_buffer(tty);
+	ld = tty_ldisc_ref(tty);
+	if (ld != NULL) {
+		if (ld->flush_buffer) 
+			ld->flush_buffer(tty);
+		tty_ldisc_deref(ld);
+	}
 	tty->closing = 0;
 
 	port->event = 0;

diff -urN linux-2.2.26.orig/drivers/char/isicom.c linux-2.2.26/drivers/char/isicom.c
@@ -621,10 +621,8 @@
 	
 	if (!tty)
 		return;
-	
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-	    tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup)(tty);
+
+	tty_wakeup(tty);
 	wake_up_interruptible(&tty->write_wait);
 } 		
  		

@@ -1349,7 +1347,8 @@
 	struct isi_port * port = (struct isi_port *) tty->driver_data;
 	struct isi_board * card;
 	unsigned long flags;
-	
+	struct tty_ldisc *ld;
+
 #ifdef ISICOM_DEBUG		
 	printk(KERN_DEBUG "ISICOM: Close start!!!.\n");
 #endif	

@@ -1417,6 +1416,12 @@
 	isicom_shutdown_port(port);
 	if (tty->driver.flush_buffer)
 		tty->driver.flush_buffer(tty);
+	ld = tty_ldisc_ref(tty);
+	if (ld != NULL) {
+		if (ld->flush_buffer)
+		ld->flush_buffer(tty);
+		tty_ldisc_deref(ld);
+	}
 	if (tty->ldisc.flush_buffer)
 		tty->ldisc.flush_buffer(tty);
 

@@ -1912,9 +1917,7 @@
 	spin_unlock_irqrestore(&card->card_lock, flags);
 	
 	wake_up_interruptible(&tty->write_wait);
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-	    tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup)(tty);
+	tty_wakeup(tty);
 }
 
 

diff -urN linux-2.2.26.orig/drivers/char/moxa.c linux-2.2.26/drivers/char/moxa.c
@@ -616,6 +616,7 @@
 {
 	struct moxa_str *ch;
 	int port;
+	struct tty_ldisc *ld;
 
 	port = PORTNO(tty);
 	if (port == MAX_PORTS) {

@@ -673,8 +674,13 @@
 
 	if (tty->driver.flush_buffer)
 		tty->driver.flush_buffer(tty);
-	if (tty->ldisc.flush_buffer)
-		tty->ldisc.flush_buffer(tty);
+
+	ld = tty_ldisc_ref(tty);
+	if (ld != NULL) {
+		if (ld->flush_buffer)
+			ld->flush_buffer(tty);
+		tty_ldisc_deref(ld);
+	}
 	tty->closing = 0;
 	ch->event = 0;
 	ch->tty = 0;

@@ -750,9 +756,7 @@
 	if (ch == NULL)
 		return;
 	MoxaPortFlushData(ch->port, 1);
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-	    tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup) (tty);
+	tty_wakeup(tty);
 	wake_up_interruptible(&tty->write_wait);
 	wake_up_interruptible(&tty->poll_wait);
 }

@@ -989,7 +993,6 @@
 		moxaTimer.function = moxa_poll;
 		moxaTimer.expires = jiffies + (HZ / 50);
 		moxaTimer_on = 1;
-		add_timer(&moxaTimer);
 		return;
 	}
 	for (card = 0; card < MAX_BOARDS; card++) {

@@ -1008,9 +1011,7 @@
 				if (MoxaPortTxQueue(ch->port) <= WAKEUP_CHARS) {
 					if (!tp->stopped) {
 						ch->statusflags &= ~LOWWAIT;
-						if ((tp->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-						  tp->ldisc.write_wakeup)
-							(tp->ldisc.write_wakeup) (tp);
+						tty_wakeup(tp);
 						wake_up_interruptible(&tp->write_wait);
 						wake_up_interruptible(&tp->poll_wait);
 					}

@@ -1199,9 +1200,7 @@
 	if (ch->tty && (ch->statusflags & EMPTYWAIT)) {
 		if (MoxaPortTxQueue(ch->port) == 0) {
 			ch->statusflags &= ~EMPTYWAIT;
-			if ((ch->tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-			    ch->tty->ldisc.write_wakeup)
-				(ch->tty->ldisc.write_wakeup) (ch->tty);
+			tty_wakeup(ch->tty);
 			wake_up_interruptible(&ch->tty->write_wait);
 			wake_up_interruptible(&ch->tty->poll_wait);
 			return;

diff -urN linux-2.2.26.orig/drivers/char/mxser.c linux-2.2.26/drivers/char/mxser.c
@@ -712,9 +712,7 @@
 	if (!tty)
 		return;
 	if (test_and_clear_bit(MXSER_EVENT_TXLOW, &info->event)) {
-		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-		    tty->ldisc.write_wakeup)
-			(tty->ldisc.write_wakeup) (tty);
+		tty_wakeup(tty);
 		wake_up_interruptible(&tty->write_wait);
 		wake_up_interruptible(&tty->poll_wait);
 	}

@@ -796,6 +794,7 @@
 	struct mxser_struct *info = (struct mxser_struct *) tty->driver_data;
 	unsigned long flags;
 	unsigned long timeout;
+	struct tty_ldisc *ld;
 
 	if (PORTNO(tty) == MXSER_PORTS)
 		return;

@@ -876,6 +875,12 @@
 	mxser_shutdown(info);
 	if (tty->driver.flush_buffer)
 		tty->driver.flush_buffer(tty);
+	ld = tty_ldisc_ref(tty);
+	if (ld) {
+		if (ld->flush_buffer)
+			ld->flush_buffer(tty);
+			tty_ldisc_deref(ld);
+	}
 	if (tty->ldisc.flush_buffer)
 		tty->ldisc.flush_buffer(tty);
 	tty->closing = 0;

@@ -1013,9 +1018,7 @@
 	restore_flags(flags);
 	wake_up_interruptible(&tty->write_wait);
 	wake_up_interruptible(&tty->poll_wait);
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-	    tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup) (tty);
+	tty_wakeup(tty);
 }
 
 static int mxser_ioctl(struct tty_struct *tty, struct file *file,

459 lines not on this page · raw message

diff -urN linux-2.2.26.orig/drivers/char/pcxx.c linux-2.2.26/drivers/char/pcxx.c
@@ -621,10 +621,10 @@
 ** please send me a note.  [email protected]
 ** Don't know either what this is supposed to do [email protected].
 */
-		if(tty->ldisc.num != ldiscs[N_TTY].num) {
+		if(tty->ldisc.num != N_TTY) {
 			if(tty->ldisc.close)
 				(tty->ldisc.close)(tty);
-			tty->ldisc = ldiscs[N_TTY];
+			tty->ldisc = *(tty_ldisc_get(N_TTY));
 			tty->termios->c_line = N_TTY;
 			if(tty->ldisc.open)
 				(tty->ldisc.open)(tty);

diff -urN linux-2.2.26.orig/drivers/char/pty.c linux-2.2.26/drivers/char/pty.c
@@ -134,6 +134,10 @@
  *   (2) avoid redundant copying for cases where count >> receive_room
  * N.B. Calls from user space may now return an error code instead of
  * a count.
+ *
+ * FIXME: Our pty_write method is called with our ldisc lock held but
+ * not our partners. We can't just take the other one blindly without
+ + * risking deadlocks. There is also the small matter of TTY_DONT_FLIP
  */
 static int pty_write(struct tty_struct * tty, int from_user,
 		       const unsigned char *buf, int count)

diff -urN linux-2.2.26.orig/drivers/char/riscom8.c linux-2.2.26/drivers/char/riscom8.c
@@ -1110,7 +1110,8 @@
 	struct riscom_board *bp;
 	unsigned long flags;
 	unsigned long timeout;
-	
+	struct tty_ldisc *ld;
+
 	if (!port || rc_paranoia_check(port, tty->device, "close"))
 		return;
 	

@@ -1180,6 +1181,12 @@
 	rc_shutdown_port(bp, port);
 	if (tty->driver.flush_buffer)
 		tty->driver.flush_buffer(tty);
+	ld = tty_ldisc_ref(tty);
+	if (ld != NULL) {
+		if(ld->flush_buffer)
+			ld->flush_buffer(tty);
+		tty_ldisc_deref(ld);
+	}
 	if (tty->ldisc.flush_buffer)
 		tty->ldisc.flush_buffer(tty);
 	tty->closing = 0;

@@ -1358,9 +1365,7 @@
 	
 	wake_up_interruptible(&tty->write_wait);
 	wake_up_interruptible(&tty->poll_wait);
-	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-	    tty->ldisc.write_wakeup)
-		(tty->ldisc.write_wakeup)(tty);
+	tty_wakeup(tty);
 }
 
 static int rc_get_modem_info(struct riscom_port * port, unsigned int *value)

@@ -1736,9 +1741,7 @@
 		return;
 
 	if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &port->event)) {
-		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
-		    tty->ldisc.write_wakeup)
-			(tty->ldisc.write_wakeup)(tty);
+		tty_wakeup(tty);
 		wake_up_interruptible(&tty->write_wait);
 		wake_up_interruptible(&tty->poll_wait);
 	}

diff -urN linux-2.2.26.orig/drivers/char/selection.c linux-2.2.26/drivers/char/selection.c
@@ -296,9 +296,11 @@
 {
 	struct vt_struct *vt = (struct vt_struct *) tty->driver_data;
 	int	pasted = 0, count;
+	struct tty_ldisc *ld;
 	struct wait_queue wait = { current, NULL };
 
 	poke_blanked_console();
+	ld = tty_ldisc_ref_wait(tty);
 	add_wait_queue(&vt->paste_wait, &wait);
 	while (sel_buffer && sel_buffer_lth > pasted) {
 		current->state = TASK_INTERRUPTIBLE;

@@ -313,6 +315,8 @@
 	}
 	remove_wait_queue(&vt->paste_wait, &wait);
 	current->state = TASK_RUNNING;
+
+	tty_ldisc_deref(ld);
 	return 0;
 }
 

diff -urN linux-2.2.26.orig/drivers/char/serial167.c linux-2.2.26/drivers/char/serial167.c
@@ -1943,10 +1943,10 @@
 	tty->ldisc.flush_buffer(tty);
     info->event = 0;
     info->tty = 0;
-    if (tty->ldisc.num != ldiscs[N_TTY].num) {
+    if (tty->ldisc.num != N_TTY) {
 	if (tty->ldisc.close)
 	    (tty->ldisc.close)(tty);
-	tty->ldisc = ldiscs[N_TTY];
+	tty->ldisc = *(tty_ldisc_get(N_TTY));
 	tty->termios->c_line = N_TTY;
 	if (tty->ldisc.open)
 	    (tty->ldisc.open)(tty);

103 lines not on this page · raw message

747 lines not on this page · raw message

159 lines not on this page · raw message

diff -urN linux-2.2.26.orig/drivers/net/slip.c linux-2.2.26/drivers/net/slip.c
@@ -669,7 +669,9 @@
  * Handle the 'receiver data ready' interrupt.
  * This function is called by the 'tty_io' module in the kernel when
  * a block of SLIP data has been received, which can now be decapsulated
- * and sent on to some IP layer for further processing.
+ * and sent on to some IP layer for further processing. This will not
+ * be re-entered while running but other ldisc functions may be called
+ * in parallel
  */
  
 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)

@@ -824,9 +826,11 @@
  * SLIP line discipline is called for.  Because we are
  * sure the tty line exists, we only have to link it to
  * a free SLIP channel...
+ *
+ * Called in process context serialized from other ldisc calls.
  */
-static int
-slip_open(struct tty_struct *tty)
+
+static int slip_open(struct tty_struct *tty)
 {
 	struct slip *sl;
 	int err;

@@ -908,6 +912,9 @@
 }
 
 /*
+
+ FIXME: 1,2 are fixed 3 was never true anyway.
+ 
    Let me to blame a bit.
    1. TTY module calls this funstion on soft interrupt.
    2. TTY module calls this function WITH MASKED INTERRUPTS!

@@ -926,9 +933,8 @@
 
 /*
  * Close down a SLIP channel.
- * This means flushing out any pending queues, and then restoring the
- * TTY line discipline to what it was before it got hooked to SLIP
- * (which usually is TTY again).
+ * This means flushing out any pending queues, and then returning. This
+ * call is serialized against other ldisc functions 
  */
 static void
 slip_close(struct tty_struct *tty)

diff -urN linux-2.2.26.orig/drivers/sbus/char/zs.c linux-2.2.26/drivers/sbus/char/zs.c
@@ -1606,10 +1606,10 @@
 	tty->closing = 0;
 	info->event = 0;
 	info->tty = 0;
-	if (tty->ldisc.num != ldiscs[N_TTY].num) {
+	if (tty->ldisc.num != N_TTY) {
 		if (tty->ldisc.close)
 			(tty->ldisc.close)(tty);
-		tty->ldisc = ldiscs[N_TTY];
+		tty->ldisc = *(tty_ldisc_get(N_TTY));
 		tty->termios->c_line = N_TTY;
 		if (tty->ldisc.open)
 			(tty->ldisc.open)(tty);

diff -urN linux-2.2.26.orig/drivers/sgi/char/sgiserial.c linux-2.2.26/drivers/sgi/char/sgiserial.c
@@ -1465,10 +1465,10 @@
 	tty->closing = 0;
 	info->event = 0;
 	info->tty = 0;
-	if (tty->ldisc.num != ldiscs[N_TTY].num) {
+	if (tty->ldisc.num != N_TTY) {
 		if (tty->ldisc.close)
 			(tty->ldisc.close)(tty);
-		tty->ldisc = ldiscs[N_TTY];
+		tty->ldisc = *(tty_ldisc_get(N_TTY));
 		tty->termios->c_line = N_TTY;
 		if (tty->ldisc.open)
 			(tty->ldisc.open)(tty);

diff -urN linux-2.2.26.orig/fs/proc/proc_tty.c linux-2.2.26/fs/proc/proc_tty.c
@@ -15,8 +15,6 @@
 #include <asm/bitops.h>
 
 extern struct tty_driver *tty_drivers;	/* linked list of tty drivers */
-extern struct tty_ldisc ldiscs[];
-
 
 static int tty_drivers_read_proc(char *page, char **start, off_t off,
 				 int count, int *eof, void *data);

@@ -112,16 +110,20 @@
 	int	len = 0;
 	off_t	begin = 0;
 	off_t	end;
+	struct tty_ldisc *ld;
 
 	end = off + count;	/* XXX: undefined on overflow per ISO C99 */
 	if (end < off)
 		return -EINVAL;
 
 	for (i=0; i < NR_LDISCS; i++) {
-		if (!(ldiscs[i].flags & LDISC_FLAG_DEFINED))
+		ld = tty_ldisc_get(i);
+		if (ld == NULL)
+		
 			continue;
 		len += sprintf(page+len, "%-10s %2d\n",
-			       ldiscs[i].name ? ldiscs[i].name : "???", i);
+			ld->name ? ld->name : "???", i);
+			tty_ldisc_put(i);
 		if (len+begin > end)
 			break;
 		if (len+begin < off) {

diff -urN linux-2.2.26.orig/include/linux/tty.h linux-2.2.26/include/linux/tty.h
@@ -319,19 +319,21 @@
  * tty->write.  Thus, you must use the inline functions set_bit() and
  * clear_bit() to make things atomic.
  */
-#define TTY_THROTTLED 0
-#define TTY_IO_ERROR 1
-#define TTY_OTHER_CLOSED 2
-#define TTY_EXCLUSIVE 3
-#define TTY_DEBUG 4
-#define TTY_DO_WRITE_WAKEUP 5
-#define TTY_PUSH 6
-#define TTY_CLOSING 7
-#define TTY_DONT_FLIP 8
-#define TTY_HW_COOK_OUT 14
-#define TTY_HW_COOK_IN 15
-#define TTY_PTY_LOCK 16
-#define TTY_NO_WRITE_SPLIT 17
+#define TTY_THROTTLED 0		/* Call unthrottle() at threshold min */
+#define TTY_IO_ERROR 1		/* Canse an I/O error (may be no ldisc too) */
+#define TTY_OTHER_CLOSED 2	/* Other side (if any) has closed */
+#define TTY_EXCLUSIVE 3		/* Exclusive open mode */
+#define TTY_DEBUG 4		/* Debugging */
+#define TTY_DO_WRITE_WAKEUP 5	/* Call write_wakeup after queuing new */
+#define TTY_PUSH 6		/* n_tty private */
+#define TTY_CLOSING 7		/* ->close() in progress */
+#define TTY_DONT_FLIP 8		/* Defer buffer flip */
+#define TTY_LDISC 9		/* Line discipline attached */
+#define TTY_HW_COOK_OUT 14	/* Hardware can do output cooking */
+#define TTY_HW_COOK_IN 15	/* Hardware can do input cooking */
+#define TTY_PTY_LOCK 16		/* pty private */
+#define TTY_NO_WRITE_SPLIT 17	/* Preserve write boundaries to driver */
+#define TTY_HUPPED 18		/* Post driver->hangup() */
 
 #define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
 

@@ -339,7 +341,7 @@
 
 extern struct termios tty_std_termios;
 extern struct tty_struct * redirect;
-extern struct tty_ldisc ldiscs[];
+extern struct tty_ldisc tty_ldiscs[];
 extern int fg_console, last_console, want_console;
 
 extern int kmsg_redirect;

@@ -393,6 +395,16 @@
 extern void tty_flip_buffer_push(struct tty_struct *tty);
 extern int tty_get_baud_rate(struct tty_struct *tty);
 
+extern struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
+extern void tty_ldisc_deref(struct tty_ldisc *);
+extern struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
+
+extern struct tty_ldisc *tty_ldisc_get(int);
+extern void tty_ldisc_put(int);
+
+extern void tty_wakeup(struct tty_struct *tty);
+
+
 /* n_tty.c */
 extern struct tty_ldisc tty_ldisc_N_TTY;
 

diff -urN linux-2.2.26.orig/include/linux/tty_ldisc.h linux-2.2.26/include/linux/tty_ldisc.h
@@ -129,6 +129,7 @@
 			       char *fp, int count);
 	int	(*receive_room)(struct tty_struct *);
 	void	(*write_wakeup)(struct tty_struct *);
+int refcount;
 };
 
 #define TTY_LDISC_MAGIC	0x5403