1 files changed, 62 insertions, 51 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 34aacaaae14a..cb8017aa4434 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -105,6 +105,7 @@ struct n_tty_data {
 
 	/* must hold exclusive termios_rwsem to reset these */
 	unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
+	unsigned char push:1;
 
 	/* shared by producer and consumer */
 	char read_buf[N_TTY_BUF_SIZE];
@@ -275,7 +276,8 @@ static void n_tty_check_unthrottle(struct tty_struct *tty)
 			return;
 		n_tty_set_room(tty);
 		n_tty_write_wakeup(tty->link);
-		wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
+		if (waitqueue_active(&tty->link->write_wait))
+			wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
 		return;
 	}
 
@@ -342,6 +344,7 @@ static void reset_buffer_flags(struct n_tty_data *ldata)
 
 	ldata->erasing = 0;
 	bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
+	ldata->push = 0;
 }
 
 static void n_tty_packet_mode_flush(struct tty_struct *tty)
@@ -351,7 +354,8 @@ static void n_tty_packet_mode_flush(struct tty_struct *tty)
 	spin_lock_irqsave(&tty->ctrl_lock, flags);
 	if (tty->link->packet) {
 		tty->ctrl_status |= TIOCPKT_FLUSHREAD;
-		wake_up_interruptible(&tty->link->read_wait);
+		if (waitqueue_active(&tty->link->read_wait))
+			wake_up_interruptible(&tty->link->read_wait);
 	}
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 }
@@ -1162,7 +1166,8 @@ static void n_tty_receive_break(struct tty_struct *tty)
 		put_tty_queue('\0', ldata);
 	}
 	put_tty_queue('\0', ldata);
-	wake_up_interruptible(&tty->read_wait);
+	if (waitqueue_active(&tty->read_wait))
+		wake_up_interruptible(&tty->read_wait);
 }
 
 /**
@@ -1220,7 +1225,8 @@ static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
 		put_tty_queue('\0', ldata);
 	else
 		put_tty_queue(c, ldata);
-	wake_up_interruptible(&tty->read_wait);
+	if (waitqueue_active(&tty->read_wait))
+		wake_up_interruptible(&tty->read_wait);
 }
 
 static void
@@ -1264,7 +1270,6 @@ static int
 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	int parmrk;
 
 	if (I_IXON(tty)) {
 		if (c == START_CHAR(tty)) {
@@ -1349,8 +1354,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
 		}
 		if ((c == EOL_CHAR(tty)) ||
 		    (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
-			parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
-				 ? 1 : 0;
 			/*
 			 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
 			 */
@@ -1365,7 +1368,7 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
 			 * XXX does PARMRK doubling happen for
 			 * EOL_CHAR and EOL2_CHAR?
 			 */
-			if (parmrk)
+			if (c == (unsigned char) '\377' && I_PARMRK(tty))
 				put_tty_queue(c, ldata);
 
 handle_newline:
@@ -1379,7 +1382,6 @@ handle_newline:
 		}
 	}
 
-	parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
 	if (L_ECHO(tty)) {
 		finish_erasing(ldata);
 		if (c == '\n')
@@ -1393,7 +1395,8 @@ handle_newline:
 		commit_echoes(tty);
 	}
 
-	if (parmrk)
+	/* PARMRK doubling check */
+	if (c == (unsigned char) '\377' && I_PARMRK(tty))
 		put_tty_queue(c, ldata);
 
 	put_tty_queue(c, ldata);
@@ -1404,7 +1407,6 @@ static inline void
 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	int parmrk;
 
 	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
 		start_tty(tty);
@@ -1418,13 +1420,13 @@ n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
 		echo_char(c, tty);
 		commit_echoes(tty);
 	}
-	parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-	if (parmrk)
+	/* PARMRK doubling check */
+	if (c == (unsigned char) '\377' && I_PARMRK(tty))
 		put_tty_queue(c, ldata);
 	put_tty_queue(c, ldata);
 }
 
-static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
+static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 {
 	n_tty_receive_char_inline(tty, c);
 }
@@ -1449,8 +1451,7 @@ n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
 	put_tty_queue(c, ldata);
 }
 
-static inline void
-n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
+static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
 {
 	if (I_ISTRIP(tty))
 		c &= 0x7f;
@@ -1681,32 +1682,9 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
 	}
 }
 
-static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-			      char *fp, int count)
-{
-	int room, n;
-
-	down_read(&tty->termios_rwsem);
-
-	while (1) {
-		room = receive_room(tty);
-		n = min(count, room);
-		if (!n)
-			break;
-		__receive_buf(tty, cp, fp, n);
-		cp += n;
-		if (fp)
-			fp += n;
-		count -= n;
-	}
-
-	tty->receive_room = room;
-	n_tty_check_throttle(tty);
-	up_read(&tty->termios_rwsem);
-}
-
-static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
-			      char *fp, int count)
+static int
+n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
+			 char *fp, int count, int flow)
 {
 	struct n_tty_data *ldata = tty->disc_data;
 	int room, n, rcvd = 0;
@@ -1717,7 +1695,7 @@ static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
 		room = receive_room(tty);
 		n = min(count, room);
 		if (!n) {
-			if (!room)
+			if (flow && !room)
 				ldata->no_room = 1;
 			break;
 		}
@@ -1736,6 +1714,18 @@ static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
 	return rcvd;
 }
 
+static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+			      char *fp, int count)
+{
+	n_tty_receive_buf_common(tty, cp, fp, count, 0);
+}
+
+static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
+			      char *fp, int count)
+{
+	return n_tty_receive_buf_common(tty, cp, fp, count, 1);
+}
+
 int is_ignored(int sig)
 {
 	return (sigismember(&current->blocked, sig) ||
@@ -1762,7 +1752,16 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 
 	if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
 		bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
-		ldata->line_start = ldata->canon_head = ldata->read_tail;
+		ldata->line_start = ldata->read_tail;
+		if (!L_ICANON(tty) || !read_cnt(ldata)) {
+			ldata->canon_head = ldata->read_tail;
+			ldata->push = 0;
+		} else {
+			set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
+				ldata->read_flags);
+			ldata->canon_head = ldata->read_head;
+			ldata->push = 1;
+		}
 		ldata->erasing = 0;
 		ldata->lnext = 0;
 	}
@@ -1825,8 +1824,10 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 		start_tty(tty);
 
 	/* The termios change make the tty ready for I/O */
-	wake_up_interruptible(&tty->write_wait);
-	wake_up_interruptible(&tty->read_wait);
+	if (waitqueue_active(&tty->write_wait))
+		wake_up_interruptible(&tty->write_wait);
+	if (waitqueue_active(&tty->read_wait))
+		wake_up_interruptible(&tty->read_wait);
 }
 
 /**
@@ -1892,14 +1893,15 @@ err:
 	return -ENOMEM;
 }
 
-static inline int input_available_p(struct tty_struct *tty, int amt)
+static inline int input_available_p(struct tty_struct *tty, int poll)
 {
 	struct n_tty_data *ldata = tty->disc_data;
+	int amt = poll && !TIME_CHAR(tty) ? MIN_CHAR(tty) : 1;
 
 	if (ldata->icanon && !L_EXTPROC(tty)) {
 		if (ldata->canon_head != ldata->read_tail)
 			return 1;
-	} else if (read_cnt(ldata) >= (amt ? amt : 1))
+	} else if (read_cnt(ldata) >= amt)
 		return 1;
 
 	return 0;
@@ -1965,6 +1967,12 @@ static int copy_from_read_buf(struct tty_struct *tty,
  *	it copies one line of input up to and including the line-delimiting
  *	character into the user-space buffer.
  *
+ *	NB: When termios is changed from non-canonical to canonical mode and
+ *	the read buffer contains data, n_tty_set_termios() simulates an EOF
+ *	push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
+ *	This causes data already processed as input to be immediately available
+ *	as input although a newline has not been received.
+ *
  *	Called under the atomic_read_lock mutex
  *
  *	n_tty_read()/consumer path:
@@ -2011,7 +2019,7 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	n += found;
 	c = n;
 
-	if (found && read_buf(ldata, eol) == __DISABLED_CHAR) {
+	if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
 		n--;
 		eof_push = !n && ldata->read_tail != ldata->line_start;
 	}
@@ -2038,7 +2046,10 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	ldata->read_tail += c;
 
 	if (found) {
-		ldata->line_start = ldata->read_tail;
+		if (!ldata->push)
+			ldata->line_start = ldata->read_tail;
+		else
+			ldata->push = 0;
 		tty_audit_push(tty);
 	}
 	return eof_push ? -EAGAIN : 0;
@@ -2398,7 +2409,7 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
 
 	poll_wait(file, &tty->read_wait, wait);
 	poll_wait(file, &tty->write_wait, wait);
-	if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
+	if (input_available_p(tty, 1))
 		mask |= POLLIN | POLLRDNORM;
 	if (tty->packet && tty->link->ctrl_status)
 		mask |= POLLPRI | POLLIN | POLLRDNORM;