Merge branch 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6

* 'tty-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
  n_gsm: Fix length handling
  n_gsm: Copy n2 over when configuring via ioctl interface
  serial: bfin_5xx: grab port lock before making port termios changes
  serial: bfin_5xx: disable CON_PRINTBUFFER for consoles
  serial: bfin_5xx: remove redundant SSYNC to improve TX speed
  serial: bfin_5xx: always include DMA headers
  vcs: make proper usage of the poll flags
  amiserial: Remove unused variable icount
  8250: Fix tcsetattr to avoid ioctl(TIOCMIWAIT) hang
  tty_ldisc: Fix BUG() on hangup
  TTY: restore tty_ldisc_wait_idle
  SERIAL: blacklist si3052 chip
  drivers/serial/bfin_5xx.c: Fix line continuation defects
  tty: prevent DOS in the flush_to_ldisc
  8250: add support for Kouwell KW-L221N-2
  nozomi: Fix warning from the previous TIOCGCOUNT changes
  tty: fix warning in synclink driver
  tty: Fix formatting in tty.h
  tty: the development tree is now done in git

4 files changed, 60 insertions, 14 deletions

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 04ef3ef0a42..81b46585edf 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -716,8 +716,8 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
 		if (msg->len < 128)
 			*--dp = (msg->len << 1) | EA;
 		else {
-			*--dp = (msg->len >> 6) | EA;
-			*--dp = (msg->len & 127) << 1;
+			*--dp = ((msg->len & 127) << 1) | EA;
+			*--dp = (msg->len >> 6) & 0xfe;
 		}
 	}
 
@@ -2375,6 +2375,7 @@ static int gsmld_config(struct tty_struct *tty, struct gsm_mux *gsm,
 	gsm->mru = c->mru;
 	gsm->encoding = c->encapsulation;
 	gsm->adaption = c->adaption;
+	gsm->n2 = c->n2;
 
 	if (c->i == 1)
 		gsm->ftype = UIH;
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index cc1e9850d65..d8210ca0072 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -413,7 +413,8 @@ static void flush_to_ldisc(struct work_struct *work)
 	spin_lock_irqsave(&tty->buf.lock, flags);
 
 	if (!test_and_set_bit(TTY_FLUSHING, &tty->flags)) {
-		struct tty_buffer *head;
+		struct tty_buffer *head, *tail = tty->buf.tail;
+		int seen_tail = 0;
 		while ((head = tty->buf.head) != NULL) {
 			int count;
 			char *char_buf;
@@ -423,6 +424,15 @@ static void flush_to_ldisc(struct work_struct *work)
 			if (!count) {
 				if (head->next == NULL)
 					break;
+				/*
+				  There's a possibility tty might get new buffer
+				  added during the unlock window below. We could
+				  end up spinning in here forever hogging the CPU
+				  completely. To avoid this let's have a rest each
+				  time we processed the tail buffer.
+				*/
+				if (tail == head)
+					seen_tail = 1;
 				tty->buf.head = head->next;
 				tty_buffer_free(tty, head);
 				continue;
@@ -432,7 +442,7 @@ static void flush_to_ldisc(struct work_struct *work)
 			   line discipline as we want to empty the queue */
 			if (test_bit(TTY_FLUSHPENDING, &tty->flags))
 				break;
-			if (!tty->receive_room) {
+			if (!tty->receive_room || seen_tail) {
 				schedule_delayed_work(&tty->buf.work, 1);
 				break;
 			}
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 412f9775d19..d8e96b00502 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -47,6 +47,7 @@
 
 static DEFINE_SPINLOCK(tty_ldisc_lock);
 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
+static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle);
 /* Line disc dispatch table */
 static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
 
@@ -83,6 +84,7 @@ static void put_ldisc(struct tty_ldisc *ld)
 		return;
 	}
 	local_irq_restore(flags);
+	wake_up(&tty_ldisc_idle);
 }
 
 /**
@@ -531,6 +533,23 @@ static int tty_ldisc_halt(struct tty_struct *tty)
 }
 
 /**
+ *	tty_ldisc_wait_idle	-	wait for the ldisc to become idle
+ *	@tty: tty to wait for
+ *
+ *	Wait for the line discipline to become idle. The discipline must
+ *	have been halted for this to guarantee it remains idle.
+ */
+static int tty_ldisc_wait_idle(struct tty_struct *tty)
+{
+	int ret;
+	ret = wait_event_interruptible_timeout(tty_ldisc_idle,
+			atomic_read(&tty->ldisc->users) == 1, 5 * HZ);
+	if (ret < 0)
+		return ret;
+	return ret > 0 ? 0 : -EBUSY;
+}
+
+/**
  *	tty_set_ldisc		-	set line discipline
  *	@tty: the terminal to set
  *	@ldisc: the line discipline
@@ -634,8 +653,17 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	flush_scheduled_work();
 
+	retval = tty_ldisc_wait_idle(tty);
+
 	tty_lock();
 	mutex_lock(&tty->ldisc_mutex);
+
+	/* handle wait idle failure locked */
+	if (retval) {
+		tty_ldisc_put(new_ldisc);
+		goto enable;
+	}
+
 	if (test_bit(TTY_HUPPED, &tty->flags)) {
 		/* We were raced by the hangup method. It will have stomped
 		   the ldisc data and closed the ldisc down */
@@ -669,6 +697,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	tty_ldisc_put(o_ldisc);
 
+enable:
 	/*
 	 *	Allow ldisc referencing to occur again
 	 */
@@ -714,9 +743,12 @@ static void tty_reset_termios(struct tty_struct *tty)
  *	state closed
  */
 
-static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
+static int tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
 {
-	struct tty_ldisc *ld;
+	struct tty_ldisc *ld = tty_ldisc_get(ldisc);
+
+	if (IS_ERR(ld))
+		return -1;
 
 	tty_ldisc_close(tty, tty->ldisc);
 	tty_ldisc_put(tty->ldisc);
@@ -724,10 +756,10 @@ static void tty_ldisc_reinit(struct tty_struct *tty, int ldisc)
 	/*
 	 *	Switch the line discipline back
 	 */
-	ld = tty_ldisc_get(ldisc);
-	BUG_ON(IS_ERR(ld));
 	tty_ldisc_assign(tty, ld);
 	tty_set_termios_ldisc(tty, ldisc);
+
+	return 0;
 }
 
 /**
@@ -802,13 +834,16 @@ void tty_ldisc_hangup(struct tty_struct *tty)
 	   a FIXME */
 	if (tty->ldisc) {	/* Not yet closed */
 		if (reset == 0) {
-			tty_ldisc_reinit(tty, tty->termios->c_line);
-			err = tty_ldisc_open(tty, tty->ldisc);
+
+			if (!tty_ldisc_reinit(tty, tty->termios->c_line))
+				err = tty_ldisc_open(tty, tty->ldisc);
+			else
+				err = 1;
 		}
 		/* If the re-open fails or we reset then go to N_TTY. The
 		   N_TTY open cannot fail */
 		if (reset || err) {
-			tty_ldisc_reinit(tty, N_TTY);
+			BUG_ON(tty_ldisc_reinit(tty, N_TTY));
 			WARN_ON(tty_ldisc_open(tty, tty->ldisc));
 		}
 		tty_ldisc_enable(tty);
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 273ab44cc91..eab3a1ff99e 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -553,12 +553,12 @@ static unsigned int
 vcs_poll(struct file *file, poll_table *wait)
 {
 	struct vcs_poll_data *poll = vcs_poll_data_get(file);
-	int ret = 0;
+	int ret = DEFAULT_POLLMASK|POLLERR|POLLPRI;
 
 	if (poll) {
 		poll_wait(file, &poll->waitq, wait);
-		if (!poll->seen_last_update)
-			ret = POLLIN | POLLRDNORM;
+		if (poll->seen_last_update)
+			ret = DEFAULT_POLLMASK;
 	}
 	return ret;
 }