1 files changed, 596 insertions, 453 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index a69470e02bf..f44f1ba762c 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -50,6 +50,7 @@
 #include <linux/uaccess.h>
 #include <linux/module.h>
 #include <linux/ratelimit.h>
+#include <linux/vmalloc.h>
 
 
 /* number of characters left in xmit buffer before select has we have room */
@@ -74,6 +75,11 @@
 #define ECHO_OP_SET_CANON_COL 0x81
 #define ECHO_OP_ERASE_TAB 0x82
 
+#define ECHO_COMMIT_WATERMARK	256
+#define ECHO_BLOCK		256
+#define ECHO_DISCARD_WATERMARK	N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
+
+
 #undef N_TTY_TRACE
 #ifdef N_TTY_TRACE
 # define n_tty_trace(f, args...)	trace_printk(f, ##args)
@@ -85,7 +91,10 @@ struct n_tty_data {
 	/* producer-published */
 	size_t read_head;
 	size_t canon_head;
-	DECLARE_BITMAP(process_char_map, 256);
+	size_t echo_head;
+	size_t echo_commit;
+	size_t echo_mark;
+	DECLARE_BITMAP(char_map, 256);
 
 	/* private to n_tty_receive_overrun (single-threaded) */
 	unsigned long overrun_time;
@@ -96,29 +105,26 @@ 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 echo_overrun:1;
+	unsigned char push:1;
 
 	/* shared by producer and consumer */
-	char *read_buf;
+	char read_buf[N_TTY_BUF_SIZE];
 	DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
+	unsigned char echo_buf[N_TTY_BUF_SIZE];
 
 	int minimum_to_wake;
 
 	/* consumer-published */
 	size_t read_tail;
-
-	/* protected by echo_lock */
-	unsigned char *echo_buf;
-	unsigned int echo_pos;
-	unsigned int echo_cnt;
+	size_t line_start;
 
 	/* protected by output lock */
 	unsigned int column;
 	unsigned int canon_column;
+	size_t echo_tail;
 
 	struct mutex atomic_read_lock;
 	struct mutex output_lock;
-	struct mutex echo_lock;
 };
 
 static inline size_t read_cnt(struct n_tty_data *ldata)
@@ -136,6 +142,16 @@ static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
 	return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
 }
 
+static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
+{
+	return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
+}
+
+static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
+{
+	return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
+}
+
 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
 			       unsigned char __user *ptr)
 {
@@ -229,7 +245,7 @@ static void n_tty_write_wakeup(struct tty_struct *tty)
 		kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
 }
 
-static inline void n_tty_check_throttle(struct tty_struct *tty)
+static void n_tty_check_throttle(struct tty_struct *tty)
 {
 	if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
 		return;
@@ -250,7 +266,7 @@ static inline void n_tty_check_throttle(struct tty_struct *tty)
 	__tty_set_flow_change(tty, 0);
 }
 
-static inline void n_tty_check_unthrottle(struct tty_struct *tty)
+static void n_tty_check_unthrottle(struct tty_struct *tty)
 {
 	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
 	    tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
@@ -260,7 +276,8 @@ static inline 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;
 	}
 
@@ -302,12 +319,9 @@ static inline void n_tty_check_unthrottle(struct tty_struct *tty)
  *	not active.
  */
 
-static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
+static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
 {
-	if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
-		*read_buf_addr(ldata, ldata->read_head) = c;
-		ldata->read_head++;
-	}
+	*read_buf_addr(ldata, ldata->read_head++) = c;
 }
 
 /**
@@ -324,13 +338,13 @@ static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
 static void reset_buffer_flags(struct n_tty_data *ldata)
 {
 	ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
-
-	mutex_lock(&ldata->echo_lock);
-	ldata->echo_pos = ldata->echo_cnt = ldata->echo_overrun = 0;
-	mutex_unlock(&ldata->echo_lock);
+	ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
+	ldata->echo_mark = 0;
+	ldata->line_start = 0;
 
 	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)
@@ -340,7 +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);
 }
@@ -633,33 +648,23 @@ break_out:
  *	are prioritized.  Also, when control characters are echoed with a
  *	prefixed "^", the pair is treated atomically and thus not separated.
  *
- *	Locking: output_lock to protect column state and space left,
- *		 echo_lock to protect the echo buffer
+ *	Locking: callers must hold output_lock
  */
 
-static void process_echoes(struct tty_struct *tty)
+static size_t __process_echoes(struct tty_struct *tty)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	int	space, nr;
+	int	space, old_space;
+	size_t tail;
 	unsigned char c;
-	unsigned char *cp, *buf_end;
-
-	if (!ldata->echo_cnt)
-		return;
 
-	mutex_lock(&ldata->output_lock);
-	mutex_lock(&ldata->echo_lock);
-
-	space = tty_write_room(tty);
+	old_space = space = tty_write_room(tty);
 
-	buf_end = ldata->echo_buf + N_TTY_BUF_SIZE;
-	cp = ldata->echo_buf + ldata->echo_pos;
-	nr = ldata->echo_cnt;
-	while (nr > 0) {
-		c = *cp;
+	tail = ldata->echo_tail;
+	while (ldata->echo_commit != tail) {
+		c = echo_buf(ldata, tail);
 		if (c == ECHO_OP_START) {
 			unsigned char op;
-			unsigned char *opp;
 			int no_space_left = 0;
 
 			/*
@@ -667,18 +672,13 @@ static void process_echoes(struct tty_struct *tty)
 			 * operation, get the next byte, which is either the
 			 * op code or a control character value.
 			 */
-			opp = cp + 1;
-			if (opp == buf_end)
-				opp -= N_TTY_BUF_SIZE;
-			op = *opp;
+			op = echo_buf(ldata, tail + 1);
 
 			switch (op) {
 				unsigned int num_chars, num_bs;
 
 			case ECHO_OP_ERASE_TAB:
-				if (++opp == buf_end)
-					opp -= N_TTY_BUF_SIZE;
-				num_chars = *opp;
+				num_chars = echo_buf(ldata, tail + 2);
 
 				/*
 				 * Determine how many columns to go back
@@ -704,21 +704,18 @@ static void process_echoes(struct tty_struct *tty)
 					if (ldata->column > 0)
 						ldata->column--;
 				}
-				cp += 3;
-				nr -= 3;
+				tail += 3;
 				break;
 
 			case ECHO_OP_SET_CANON_COL:
 				ldata->canon_column = ldata->column;
-				cp += 2;
-				nr -= 2;
+				tail += 2;
 				break;
 
 			case ECHO_OP_MOVE_BACK_COL:
 				if (ldata->column > 0)
 					ldata->column--;
-				cp += 2;
-				nr -= 2;
+				tail += 2;
 				break;
 
 			case ECHO_OP_START:
@@ -730,8 +727,7 @@ static void process_echoes(struct tty_struct *tty)
 				tty_put_char(tty, ECHO_OP_START);
 				ldata->column++;
 				space--;
-				cp += 2;
-				nr -= 2;
+				tail += 2;
 				break;
 
 			default:
@@ -752,8 +748,7 @@ static void process_echoes(struct tty_struct *tty)
 				tty_put_char(tty, op ^ 0100);
 				ldata->column += 2;
 				space -= 2;
-				cp += 2;
-				nr -= 2;
+				tail += 2;
 			}
 
 			if (no_space_left)
@@ -770,80 +765,96 @@ static void process_echoes(struct tty_struct *tty)
 				tty_put_char(tty, c);
 				space -= 1;
 			}
-			cp += 1;
-			nr -= 1;
+			tail += 1;
 		}
-
-		/* When end of circular buffer reached, wrap around */
-		if (cp >= buf_end)
-			cp -= N_TTY_BUF_SIZE;
 	}
 
-	if (nr == 0) {
-		ldata->echo_pos = 0;
-		ldata->echo_cnt = 0;
-		ldata->echo_overrun = 0;
-	} else {
-		int num_processed = ldata->echo_cnt - nr;
-		ldata->echo_pos += num_processed;
-		ldata->echo_pos &= N_TTY_BUF_SIZE - 1;
-		ldata->echo_cnt = nr;
-		if (num_processed > 0)
-			ldata->echo_overrun = 0;
+	/* If the echo buffer is nearly full (so that the possibility exists
+	 * of echo overrun before the next commit), then discard enough
+	 * data at the tail to prevent a subsequent overrun */
+	while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
+		if (echo_buf(ldata, tail) == ECHO_OP_START) {
+			if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
+				tail += 3;
+			else
+				tail += 2;
+		} else
+			tail++;
 	}
 
-	mutex_unlock(&ldata->echo_lock);
+	ldata->echo_tail = tail;
+	return old_space - space;
+}
+
+static void commit_echoes(struct tty_struct *tty)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+	size_t nr, old, echoed;
+	size_t head;
+
+	head = ldata->echo_head;
+	ldata->echo_mark = head;
+	old = ldata->echo_commit - ldata->echo_tail;
+
+	/* Process committed echoes if the accumulated # of bytes
+	 * is over the threshold (and try again each time another
+	 * block is accumulated) */
+	nr = head - ldata->echo_tail;
+	if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
+		return;
+
+	mutex_lock(&ldata->output_lock);
+	ldata->echo_commit = head;
+	echoed = __process_echoes(tty);
+	mutex_unlock(&ldata->output_lock);
+
+	if (echoed && tty->ops->flush_chars)
+		tty->ops->flush_chars(tty);
+}
+
+static void process_echoes(struct tty_struct *tty)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+	size_t echoed;
+
+	if (ldata->echo_mark == ldata->echo_tail)
+		return;
+
+	mutex_lock(&ldata->output_lock);
+	ldata->echo_commit = ldata->echo_mark;
+	echoed = __process_echoes(tty);
 	mutex_unlock(&ldata->output_lock);
 
-	if (tty->ops->flush_chars)
+	if (echoed && tty->ops->flush_chars)
 		tty->ops->flush_chars(tty);
 }
 
+/* NB: echo_mark and echo_head should be equivalent here */
+static void flush_echoes(struct tty_struct *tty)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+
+	if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
+	    ldata->echo_commit == ldata->echo_head)
+		return;
+
+	mutex_lock(&ldata->output_lock);
+	ldata->echo_commit = ldata->echo_head;
+	__process_echoes(tty);
+	mutex_unlock(&ldata->output_lock);
+}
+
 /**
  *	add_echo_byte	-	add a byte to the echo buffer
  *	@c: unicode byte to echo
  *	@ldata: n_tty data
  *
  *	Add a character or operation byte to the echo buffer.
- *
- *	Should be called under the echo lock to protect the echo buffer.
  */
 
-static void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
+static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
 {
-	int	new_byte_pos;
-
-	if (ldata->echo_cnt == N_TTY_BUF_SIZE) {
-		/* Circular buffer is already at capacity */
-		new_byte_pos = ldata->echo_pos;
-
-		/*
-		 * Since the buffer start position needs to be advanced,
-		 * be sure to step by a whole operation byte group.
-		 */
-		if (ldata->echo_buf[ldata->echo_pos] == ECHO_OP_START) {
-			if (ldata->echo_buf[(ldata->echo_pos + 1) &
-					  (N_TTY_BUF_SIZE - 1)] ==
-						ECHO_OP_ERASE_TAB) {
-				ldata->echo_pos += 3;
-				ldata->echo_cnt -= 2;
-			} else {
-				ldata->echo_pos += 2;
-				ldata->echo_cnt -= 1;
-			}
-		} else {
-			ldata->echo_pos++;
-		}
-		ldata->echo_pos &= N_TTY_BUF_SIZE - 1;
-
-		ldata->echo_overrun = 1;
-	} else {
-		new_byte_pos = ldata->echo_pos + ldata->echo_cnt;
-		new_byte_pos &= N_TTY_BUF_SIZE - 1;
-		ldata->echo_cnt++;
-	}
-
-	ldata->echo_buf[new_byte_pos] = c;
+	*echo_buf_addr(ldata, ldata->echo_head++) = c;
 }
 
 /**
@@ -851,16 +862,12 @@ static void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
  *	@ldata: n_tty data
  *
  *	Add an operation to the echo buffer to move back one column.
- *
- *	Locking: echo_lock to protect the echo buffer
  */
 
 static void echo_move_back_col(struct n_tty_data *ldata)
 {
-	mutex_lock(&ldata->echo_lock);
 	add_echo_byte(ECHO_OP_START, ldata);
 	add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
-	mutex_unlock(&ldata->echo_lock);
 }
 
 /**
@@ -869,16 +876,12 @@ static void echo_move_back_col(struct n_tty_data *ldata)
  *
  *	Add an operation to the echo buffer to set the canon column
  *	to the current column.
- *
- *	Locking: echo_lock to protect the echo buffer
  */
 
 static void echo_set_canon_col(struct n_tty_data *ldata)
 {
-	mutex_lock(&ldata->echo_lock);
 	add_echo_byte(ECHO_OP_START, ldata);
 	add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
-	mutex_unlock(&ldata->echo_lock);
 }
 
 /**
@@ -894,15 +897,11 @@ static void echo_set_canon_col(struct n_tty_data *ldata)
  *	of input.  This information will be used later, along with
  *	canon column (if applicable), to go back the correct number
  *	of columns.
- *
- *	Locking: echo_lock to protect the echo buffer
  */
 
 static void echo_erase_tab(unsigned int num_chars, int after_tab,
 			   struct n_tty_data *ldata)
 {
-	mutex_lock(&ldata->echo_lock);
-
 	add_echo_byte(ECHO_OP_START, ldata);
 	add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
 
@@ -914,8 +913,6 @@ static void echo_erase_tab(unsigned int num_chars, int after_tab,
 		num_chars |= 0x80;
 
 	add_echo_byte(num_chars, ldata);
-
-	mutex_unlock(&ldata->echo_lock);
 }
 
 /**
@@ -927,20 +924,16 @@ static void echo_erase_tab(unsigned int num_chars, int after_tab,
  *	L_ECHO(tty) is true. Called from the driver receive_buf path.
  *
  *	This variant does not treat control characters specially.
- *
- *	Locking: echo_lock to protect the echo buffer
  */
 
 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
 {
-	mutex_lock(&ldata->echo_lock);
 	if (c == ECHO_OP_START) {
 		add_echo_byte(ECHO_OP_START, ldata);
 		add_echo_byte(ECHO_OP_START, ldata);
 	} else {
 		add_echo_byte(c, ldata);
 	}
-	mutex_unlock(&ldata->echo_lock);
 }
 
 /**
@@ -953,16 +946,12 @@ static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
  *
  *	This variant tags control characters to be echoed as "^X"
  *	(where X is the letter representing the control char).
- *
- *	Locking: echo_lock to protect the echo buffer
  */
 
 static void echo_char(unsigned char c, struct tty_struct *tty)
 {
 	struct n_tty_data *ldata = tty->disc_data;
 
-	mutex_lock(&ldata->echo_lock);
-
 	if (c == ECHO_OP_START) {
 		add_echo_byte(ECHO_OP_START, ldata);
 		add_echo_byte(ECHO_OP_START, ldata);
@@ -971,8 +960,6 @@ static void echo_char(unsigned char c, struct tty_struct *tty)
 			add_echo_byte(ECHO_OP_START, ldata);
 		add_echo_byte(c, ldata);
 	}
-
-	mutex_unlock(&ldata->echo_lock);
 }
 
 /**
@@ -1133,7 +1120,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
  *	Locking: ctrl_lock
  */
 
-static inline void isig(int sig, struct tty_struct *tty)
+static void isig(int sig, struct tty_struct *tty)
 {
 	struct pid *tty_pgrp = tty_get_pgrp(tty);
 	if (tty_pgrp) {
@@ -1156,7 +1143,7 @@ static inline void isig(int sig, struct tty_struct *tty)
  *	Note: may get exclusive termios_rwsem if flushing input buffer
  */
 
-static inline void n_tty_receive_break(struct tty_struct *tty)
+static void n_tty_receive_break(struct tty_struct *tty)
 {
 	struct n_tty_data *ldata = tty->disc_data;
 
@@ -1178,7 +1165,8 @@ static inline 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);
 }
 
 /**
@@ -1194,7 +1182,7 @@ static inline void n_tty_receive_break(struct tty_struct *tty)
  *	private.
  */
 
-static inline void n_tty_receive_overrun(struct tty_struct *tty)
+static void n_tty_receive_overrun(struct tty_struct *tty)
 {
 	struct n_tty_data *ldata = tty->disc_data;
 	char buf[64];
@@ -1222,22 +1210,44 @@ static inline void n_tty_receive_overrun(struct tty_struct *tty)
  *		caller holds non-exclusive termios_rwsem
  *		publishes read_head via put_tty_queue()
  */
-static inline void n_tty_receive_parity_error(struct tty_struct *tty,
-					      unsigned char c)
+static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
 {
 	struct n_tty_data *ldata = tty->disc_data;
 
-	if (I_IGNPAR(tty))
-		return;
-	if (I_PARMRK(tty)) {
-		put_tty_queue('\377', ldata);
-		put_tty_queue('\0', ldata);
-		put_tty_queue(c, ldata);
-	} else	if (I_INPCK(tty))
-		put_tty_queue('\0', ldata);
-	else
+	if (I_INPCK(tty)) {
+		if (I_IGNPAR(tty))
+			return;
+		if (I_PARMRK(tty)) {
+			put_tty_queue('\377', ldata);
+			put_tty_queue('\0', ldata);
+			put_tty_queue(c, ldata);
+		} else
+			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
+n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
+{
+	if (!L_NOFLSH(tty)) {
+		/* flushing needs exclusive termios_rwsem */
+		up_read(&tty->termios_rwsem);
+		n_tty_flush_buffer(tty);
+		tty_driver_flush_buffer(tty);
+		down_read(&tty->termios_rwsem);
+	}
+	if (I_IXON(tty))
+		start_tty(tty);
+	if (L_ECHO(tty)) {
+		echo_char(c, tty);
+		commit_echoes(tty);
+	} else
+		process_echoes(tty);
+	isig(signal, tty);
+	return;
 }
 
 /**
@@ -1253,119 +1263,48 @@ static inline void n_tty_receive_parity_error(struct tty_struct *tty,
  *		caller holds non-exclusive termios_rwsem
  *		publishes canon_head if canonical mode is active
  *		otherwise, publishes read_head via put_tty_queue()
+ *
+ *	Returns 1 if LNEXT was received, else returns 0
  */
 
-static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
+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 (ldata->raw) {
-		put_tty_queue(c, ldata);
-		return;
-	}
-
-	if (I_ISTRIP(tty))
-		c &= 0x7f;
-	if (I_IUCLC(tty) && L_IEXTEN(tty))
-		c = tolower(c);
-
-	if (L_EXTPROC(tty)) {
-		put_tty_queue(c, ldata);
-		return;
-	}
-
-	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
-	    I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
-	    c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
-		start_tty(tty);
-		process_echoes(tty);
-	}
-
-	if (tty->closing) {
-		if (I_IXON(tty)) {
-			if (c == START_CHAR(tty)) {
-				start_tty(tty);
-				process_echoes(tty);
-			} else if (c == STOP_CHAR(tty))
-				stop_tty(tty);
-		}
-		return;
-	}
-
-	/*
-	 * If the previous character was LNEXT, or we know that this
-	 * character is not one of the characters that we'll have to
-	 * handle specially, do shortcut processing to speed things
-	 * up.
-	 */
-	if (!test_bit(c, ldata->process_char_map) || ldata->lnext) {
-		ldata->lnext = 0;
-		parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-		if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
-			/* beep if no space */
-			if (L_ECHO(tty))
-				process_output('\a', tty);
-			return;
-		}
-		if (L_ECHO(tty)) {
-			finish_erasing(ldata);
-			/* Record the column of first canon char. */
-			if (ldata->canon_head == ldata->read_head)
-				echo_set_canon_col(ldata);
-			echo_char(c, tty);
-			process_echoes(tty);
-		}
-		if (parmrk)
-			put_tty_queue(c, ldata);
-		put_tty_queue(c, ldata);
-		return;
-	}
 
 	if (I_IXON(tty)) {
 		if (c == START_CHAR(tty)) {
 			start_tty(tty);
 			process_echoes(tty);
-			return;
+			return 0;
 		}
 		if (c == STOP_CHAR(tty)) {
 			stop_tty(tty);
-			return;
+			return 0;
 		}
 	}
 
 	if (L_ISIG(tty)) {
-		int signal;
-		signal = SIGINT;
-		if (c == INTR_CHAR(tty))
-			goto send_signal;
-		signal = SIGQUIT;
-		if (c == QUIT_CHAR(tty))
-			goto send_signal;
-		signal = SIGTSTP;
-		if (c == SUSP_CHAR(tty)) {
-send_signal:
-			if (!L_NOFLSH(tty)) {
-				/* flushing needs exclusive termios_rwsem */
-				up_read(&tty->termios_rwsem);
-				n_tty_flush_buffer(tty);
-				tty_driver_flush_buffer(tty);
-				down_read(&tty->termios_rwsem);
-			}
-			if (I_IXON(tty))
-				start_tty(tty);
-			if (L_ECHO(tty)) {
-				echo_char(c, tty);
-				process_echoes(tty);
-			}
-			isig(signal, tty);
-			return;
+		if (c == INTR_CHAR(tty)) {
+			n_tty_receive_signal_char(tty, SIGINT, c);
+			return 0;
+		} else if (c == QUIT_CHAR(tty)) {
+			n_tty_receive_signal_char(tty, SIGQUIT, c);
+			return 0;
+		} else if (c == SUSP_CHAR(tty)) {
+			n_tty_receive_signal_char(tty, SIGTSTP, c);
+			return 0;
 		}
 	}
 
+	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
+		start_tty(tty);
+		process_echoes(tty);
+	}
+
 	if (c == '\r') {
 		if (I_IGNCR(tty))
-			return;
+			return 0;
 		if (I_ICRNL(tty))
 			c = '\n';
 	} else if (c == '\n' && I_INLCR(tty))
@@ -1375,8 +1314,8 @@ send_signal:
 		if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
 		    (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
 			eraser(c, tty);
-			process_echoes(tty);
-			return;
+			commit_echoes(tty);
+			return 0;
 		}
 		if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
 			ldata->lnext = 1;
@@ -1385,13 +1324,12 @@ send_signal:
 				if (L_ECHOCTL(tty)) {
 					echo_char_raw('^', ldata);
 					echo_char_raw('\b', ldata);
-					process_echoes(tty);
+					commit_echoes(tty);
 				}
 			}
-			return;
+			return 1;
 		}
-		if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
-		    L_IEXTEN(tty)) {
+		if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
 			size_t tail = ldata->canon_head;
 
 			finish_erasing(ldata);
@@ -1401,38 +1339,22 @@ send_signal:
 				echo_char(read_buf(ldata, tail), tty);
 				tail++;
 			}
-			process_echoes(tty);
-			return;
+			commit_echoes(tty);
+			return 0;
 		}
 		if (c == '\n') {
-			if (read_cnt(ldata) >= N_TTY_BUF_SIZE) {
-				if (L_ECHO(tty))
-					process_output('\a', tty);
-				return;
-			}
 			if (L_ECHO(tty) || L_ECHONL(tty)) {
 				echo_char_raw('\n', ldata);
-				process_echoes(tty);
+				commit_echoes(tty);
 			}
 			goto handle_newline;
 		}
 		if (c == EOF_CHAR(tty)) {
-			if (read_cnt(ldata) >= N_TTY_BUF_SIZE)
-				return;
-			if (ldata->canon_head != ldata->read_head)
-				set_bit(TTY_PUSH, &tty->flags);
 			c = __DISABLED_CHAR;
 			goto handle_newline;
 		}
 		if ((c == EOL_CHAR(tty)) ||
 		    (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
-			parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
-				 ? 1 : 0;
-			if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) {
-				if (L_ECHO(tty))
-					process_output('\a', tty);
-				return;
-			}
 			/*
 			 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
 			 */
@@ -1441,13 +1363,13 @@ send_signal:
 				if (ldata->canon_head == ldata->read_head)
 					echo_set_canon_col(ldata);
 				echo_char(c, tty);
-				process_echoes(tty);
+				commit_echoes(tty);
 			}
 			/*
 			 * 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:
@@ -1457,17 +1379,10 @@ handle_newline:
 			kill_fasync(&tty->fasync, SIGIO, POLL_IN);
 			if (waitqueue_active(&tty->read_wait))
 				wake_up_interruptible(&tty->read_wait);
-			return;
+			return 0;
 		}
 	}
 
-	parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-	if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
-		/* beep if no space */
-		if (L_ECHO(tty))
-			process_output('\a', tty);
-		return;
-	}
 	if (L_ECHO(tty)) {
 		finish_erasing(ldata);
 		if (c == '\n')
@@ -1478,13 +1393,122 @@ handle_newline:
 				echo_set_canon_col(ldata);
 			echo_char(c, tty);
 		}
-		process_echoes(tty);
+		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);
+	return 0;
+}
+
+static inline void
+n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+
+	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
+		start_tty(tty);
+		process_echoes(tty);
+	}
+	if (L_ECHO(tty)) {
+		finish_erasing(ldata);
+		/* Record the column of first canon char. */
+		if (ldata->canon_head == ldata->read_head)
+			echo_set_canon_col(ldata);
+		echo_char(c, tty);
+		commit_echoes(tty);
+	}
+	/* PARMRK doubling check */
+	if (c == (unsigned char) '\377' && I_PARMRK(tty))
+		put_tty_queue(c, ldata);
+	put_tty_queue(c, ldata);
+}
+
+static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
+{
+	n_tty_receive_char_inline(tty, c);
+}
+
+static inline void
+n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+
+	if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
+		start_tty(tty);
+		process_echoes(tty);
+	}
+	if (L_ECHO(tty)) {
+		finish_erasing(ldata);
+		/* Record the column of first canon char. */
+		if (ldata->canon_head == ldata->read_head)
+			echo_set_canon_col(ldata);
+		echo_char(c, tty);
+		commit_echoes(tty);
+	}
+	put_tty_queue(c, ldata);
+}
+
+static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
+{
+	if (I_ISTRIP(tty))
+		c &= 0x7f;
+	if (I_IUCLC(tty) && L_IEXTEN(tty))
+		c = tolower(c);
+
+	if (I_IXON(tty)) {
+		if (c == STOP_CHAR(tty))
+			stop_tty(tty);
+		else if (c == START_CHAR(tty) ||
+			 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
+			  c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
+			  c != SUSP_CHAR(tty))) {
+			start_tty(tty);
+			process_echoes(tty);
+		}
+	}
+}
+
+static void
+n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
+{
+	char buf[64];
+
+	switch (flag) {
+	case TTY_BREAK:
+		n_tty_receive_break(tty);
+		break;
+	case TTY_PARITY:
+	case TTY_FRAME:
+		n_tty_receive_parity_error(tty, c);
+		break;
+	case TTY_OVERRUN:
+		n_tty_receive_overrun(tty);
+		break;
+	default:
+		printk(KERN_ERR "%s: unknown flag %d\n",
+		       tty_name(tty, buf), flag);
+		break;
+	}
+}
+
+static void
+n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+
+	ldata->lnext = 0;
+	if (likely(flag == TTY_NORMAL)) {
+		if (I_ISTRIP(tty))
+			c &= 0x7f;
+		if (I_IUCLC(tty) && L_IEXTEN(tty))
+			c = tolower(c);
+		n_tty_receive_char(tty, c);
+	} else
+		n_tty_receive_char_flagged(tty, c, flag);
 }
 
 /**
@@ -1504,56 +1528,149 @@ handle_newline:
  *		publishes read_head and canon_head
  */
 
-static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
+static void
+n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
+			   char *fp, int count)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+	size_t n, head;
+
+	head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
+	n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
+	n = min_t(size_t, count, n);
+	memcpy(read_buf_addr(ldata, head), cp, n);
+	ldata->read_head += n;
+	cp += n;
+	count -= n;
+
+	head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
+	n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
+	n = min_t(size_t, count, n);
+	memcpy(read_buf_addr(ldata, head), cp, n);
+	ldata->read_head += n;
+}
+
+static void
+n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
+		      char *fp, int count)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+	char flag = TTY_NORMAL;
+
+	while (count--) {
+		if (fp)
+			flag = *fp++;
+		if (likely(flag == TTY_NORMAL))
+			put_tty_queue(*cp++, ldata);
+		else
+			n_tty_receive_char_flagged(tty, *cp++, flag);
+	}
+}
+
+static void
+n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
+			  char *fp, int count)
+{
+	char flag = TTY_NORMAL;
+
+	while (count--) {
+		if (fp)
+			flag = *fp++;
+		if (likely(flag == TTY_NORMAL))
+			n_tty_receive_char_closing(tty, *cp++);
+		else
+			n_tty_receive_char_flagged(tty, *cp++, flag);
+	}
+}
+
+static void
+n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
 			  char *fp, int count)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	const unsigned char *p;
-	char *f, flags = TTY_NORMAL;
-	char	buf[64];
-
-	if (ldata->real_raw) {
-		size_t n, head;
-
-		head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
-		n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
-		n = min_t(size_t, count, n);
-		memcpy(read_buf_addr(ldata, head), cp, n);
-		ldata->read_head += n;
-		cp += n;
-		count -= n;
+	char flag = TTY_NORMAL;
+
+	while (count--) {
+		if (fp)
+			flag = *fp++;
+		if (likely(flag == TTY_NORMAL)) {
+			unsigned char c = *cp++;
+
+			if (I_ISTRIP(tty))
+				c &= 0x7f;
+			if (I_IUCLC(tty) && L_IEXTEN(tty))
+				c = tolower(c);
+			if (L_EXTPROC(tty)) {
+				put_tty_queue(c, ldata);
+				continue;
+			}
+			if (!test_bit(c, ldata->char_map))
+				n_tty_receive_char_inline(tty, c);
+			else if (n_tty_receive_char_special(tty, c) && count) {
+				if (fp)
+					flag = *fp++;
+				n_tty_receive_char_lnext(tty, *cp++, flag);
+				count--;
+			}
+		} else
+			n_tty_receive_char_flagged(tty, *cp++, flag);
+	}
+}
 
-		head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
-		n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
-		n = min_t(size_t, count, n);
-		memcpy(read_buf_addr(ldata, head), cp, n);
-		ldata->read_head += n;
-	} else {
-		int i;
-
-		for (i = count, p = cp, f = fp; i; i--, p++) {
-			if (f)
-				flags = *f++;
-			switch (flags) {
-			case TTY_NORMAL:
-				n_tty_receive_char(tty, *p);
-				break;
-			case TTY_BREAK:
-				n_tty_receive_break(tty);
-				break;
-			case TTY_PARITY:
-			case TTY_FRAME:
-				n_tty_receive_parity_error(tty, *p);
-				break;
-			case TTY_OVERRUN:
-				n_tty_receive_overrun(tty);
-				break;
-			default:
-				printk(KERN_ERR "%s: unknown flag %d\n",
-				       tty_name(tty, buf), flags);
-				break;
+static void
+n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
+		       char *fp, int count)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+	char flag = TTY_NORMAL;
+
+	while (count--) {
+		if (fp)
+			flag = *fp++;
+		if (likely(flag == TTY_NORMAL)) {
+			unsigned char c = *cp++;
+
+			if (!test_bit(c, ldata->char_map))
+				n_tty_receive_char_fast(tty, c);
+			else if (n_tty_receive_char_special(tty, c) && count) {
+				if (fp)
+					flag = *fp++;
+				n_tty_receive_char_lnext(tty, *cp++, flag);
+				count--;
 			}
+		} else
+			n_tty_receive_char_flagged(tty, *cp++, flag);
+	}
+}
+
+static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
+			  char *fp, int count)
+{
+	struct n_tty_data *ldata = tty->disc_data;
+	bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
+
+	if (ldata->real_raw)
+		n_tty_receive_buf_real_raw(tty, cp, fp, count);
+	else if (ldata->raw || (L_EXTPROC(tty) && !preops))
+		n_tty_receive_buf_raw(tty, cp, fp, count);
+	else if (tty->closing && !L_EXTPROC(tty))
+		n_tty_receive_buf_closing(tty, cp, fp, count);
+	else {
+		if (ldata->lnext) {
+			char flag = TTY_NORMAL;
+
+			if (fp)
+				flag = *fp++;
+			n_tty_receive_char_lnext(tty, *cp++, flag);
+			count--;
 		}
+
+		if (!preops && !I_PARMRK(tty))
+			n_tty_receive_buf_fast(tty, cp, fp, count);
+		else
+			n_tty_receive_buf_standard(tty, cp, fp, count);
+
+		flush_echoes(tty);
 		if (tty->ops->flush_chars)
 			tty->ops->flush_chars(tty);
 	}
@@ -1564,36 +1681,50 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
 		if (waitqueue_active(&tty->read_wait))
 			wake_up_interruptible(&tty->read_wait);
 	}
+}
 
+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;
+
+	down_read(&tty->termios_rwsem);
+
+	while (1) {
+		room = receive_room(tty);
+		n = min(count, room);
+		if (!n) {
+			if (flow && !room)
+				ldata->no_room = 1;
+			break;
+		}
+		__receive_buf(tty, cp, fp, n);
+		cp += n;
+		if (fp)
+			fp += n;
+		count -= n;
+		rcvd += n;
+	}
+
+	tty->receive_room = room;
 	n_tty_check_throttle(tty);
+	up_read(&tty->termios_rwsem);
+
+	return rcvd;
 }
 
 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 			      char *fp, int count)
 {
-	down_read(&tty->termios_rwsem);
-	__receive_buf(tty, cp, fp, count);
-	up_read(&tty->termios_rwsem);
+	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)
 {
-	struct n_tty_data *ldata = tty->disc_data;
-	int room;
-
-	down_read(&tty->termios_rwsem);
-
-	tty->receive_room = room = receive_room(tty);
-	if (!room)
-		ldata->no_room = 1;
-	count = min(count, room);
-	if (count)
-		__receive_buf(tty, cp, fp, count);
-
-	up_read(&tty->termios_rwsem);
-
-	return count;
+	return n_tty_receive_buf_common(tty, cp, fp, count, 1);
 }
 
 int is_ignored(int sig)
@@ -1619,61 +1750,61 @@ int is_ignored(int sig)
 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	int canon_change = 1;
 
-	if (old)
-		canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
-	if (canon_change) {
+	if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
 		bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
-		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;
 	}
 
-	if (canon_change && !L_ICANON(tty) && read_cnt(ldata))
-		wake_up_interruptible(&tty->read_wait);
-
 	ldata->icanon = (L_ICANON(tty) != 0);
 
 	if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
 	    I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
 	    I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
 	    I_PARMRK(tty)) {
-		bitmap_zero(ldata->process_char_map, 256);
+		bitmap_zero(ldata->char_map, 256);
 
 		if (I_IGNCR(tty) || I_ICRNL(tty))
-			set_bit('\r', ldata->process_char_map);
+			set_bit('\r', ldata->char_map);
 		if (I_INLCR(tty))
-			set_bit('\n', ldata->process_char_map);
+			set_bit('\n', ldata->char_map);
 
 		if (L_ICANON(tty)) {
-			set_bit(ERASE_CHAR(tty), ldata->process_char_map);
-			set_bit(KILL_CHAR(tty), ldata->process_char_map);
-			set_bit(EOF_CHAR(tty), ldata->process_char_map);
-			set_bit('\n', ldata->process_char_map);
-			set_bit(EOL_CHAR(tty), ldata->process_char_map);
+			set_bit(ERASE_CHAR(tty), ldata->char_map);
+			set_bit(KILL_CHAR(tty), ldata->char_map);
+			set_bit(EOF_CHAR(tty), ldata->char_map);
+			set_bit('\n', ldata->char_map);
+			set_bit(EOL_CHAR(tty), ldata->char_map);
 			if (L_IEXTEN(tty)) {
-				set_bit(WERASE_CHAR(tty),
-					ldata->process_char_map);
-				set_bit(LNEXT_CHAR(tty),
-					ldata->process_char_map);
-				set_bit(EOL2_CHAR(tty),
-					ldata->process_char_map);
+				set_bit(WERASE_CHAR(tty), ldata->char_map);
+				set_bit(LNEXT_CHAR(tty), ldata->char_map);
+				set_bit(EOL2_CHAR(tty), ldata->char_map);
 				if (L_ECHO(tty))
 					set_bit(REPRINT_CHAR(tty),
-						ldata->process_char_map);
+						ldata->char_map);
 			}
 		}
 		if (I_IXON(tty)) {
-			set_bit(START_CHAR(tty), ldata->process_char_map);
-			set_bit(STOP_CHAR(tty), ldata->process_char_map);
+			set_bit(START_CHAR(tty), ldata->char_map);
+			set_bit(STOP_CHAR(tty), ldata->char_map);
 		}
 		if (L_ISIG(tty)) {
-			set_bit(INTR_CHAR(tty), ldata->process_char_map);
-			set_bit(QUIT_CHAR(tty), ldata->process_char_map);
-			set_bit(SUSP_CHAR(tty), ldata->process_char_map);
+			set_bit(INTR_CHAR(tty), ldata->char_map);
+			set_bit(QUIT_CHAR(tty), ldata->char_map);
+			set_bit(SUSP_CHAR(tty), ldata->char_map);
 		}
-		clear_bit(__DISABLED_CHAR, ldata->process_char_map);
+		clear_bit(__DISABLED_CHAR, ldata->char_map);
 		ldata->raw = 0;
 		ldata->real_raw = 0;
 	} else {
@@ -1692,11 +1823,14 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 	 */
 	if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
 		start_tty(tty);
+		process_echoes(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);
 }
 
 /**
@@ -1716,9 +1850,7 @@ static void n_tty_close(struct tty_struct *tty)
 	if (tty->link)
 		n_tty_packet_mode_flush(tty);
 
-	kfree(ldata->read_buf);
-	kfree(ldata->echo_buf);
-	kfree(ldata);
+	vfree(ldata);
 	tty->disc_data = NULL;
 }
 
@@ -1736,25 +1868,23 @@ static int n_tty_open(struct tty_struct *tty)
 {
 	struct n_tty_data *ldata;
 
-	ldata = kzalloc(sizeof(*ldata), GFP_KERNEL);
+	/* Currently a malloc failure here can panic */
+	ldata = vmalloc(sizeof(*ldata));
 	if (!ldata)
 		goto err;
 
 	ldata->overrun_time = jiffies;
 	mutex_init(&ldata->atomic_read_lock);
 	mutex_init(&ldata->output_lock);
-	mutex_init(&ldata->echo_lock);
-
-	/* These are ugly. Currently a malloc failure here can panic */
-	ldata->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
-	ldata->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
-	if (!ldata->read_buf || !ldata->echo_buf)
-		goto err_free_bufs;
 
 	tty->disc_data = ldata;
 	reset_buffer_flags(tty->disc_data);
 	ldata->column = 0;
+	ldata->canon_column = 0;
 	ldata->minimum_to_wake = 1;
+	ldata->num_overrun = 0;
+	ldata->no_room = 0;
+	ldata->lnext = 0;
 	tty->closing = 0;
 	/* indicate buffer work may resume */
 	clear_bit(TTY_LDISC_HALTED, &tty->flags);
@@ -1762,25 +1892,19 @@ static int n_tty_open(struct tty_struct *tty)
 	tty_unthrottle(tty);
 
 	return 0;
-err_free_bufs:
-	kfree(ldata->read_buf);
-	kfree(ldata->echo_buf);
-	kfree(ldata);
 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) ? 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))
-		return 1;
-
-	return 0;
+	if (ldata->icanon && !L_EXTPROC(tty))
+		return ldata->canon_head != ldata->read_tail;
+	else
+		return read_cnt(ldata) >= amt;
 }
 
 /**
@@ -1843,6 +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:
@@ -1859,6 +1989,7 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	size_t eol;
 	size_t tail;
 	int ret, found = 0;
+	bool eof_push = 0;
 
 	/* N.B. avoid overrun if nr == 0 */
 	n = min(*nr, read_cnt(ldata));
@@ -1882,11 +2013,16 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 		found = 1;
 
 	size = N_TTY_BUF_SIZE - tail;
-	n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
+	n = eol - tail;
+	if (n > 4096)
+		n += 4096;
+	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;
+	}
 
 	n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
 		    __func__, eol, found, n, c, size, more);
@@ -1906,12 +2042,17 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 
 	if (found)
 		clear_bit(eol, ldata->read_flags);
-	smp_mb__after_clear_bit();
+	smp_mb__after_atomic();
 	ldata->read_tail += c;
 
-	if (found)
+	if (found) {
+		if (!ldata->push)
+			ldata->line_start = ldata->read_tail;
+		else
+			ldata->push = 0;
 		tty_audit_push(tty);
-	return 0;
+	}
+	return eof_push ? -EAGAIN : 0;
 }
 
 extern ssize_t redirected_tty_write(struct file *, const char __user *,
@@ -1986,16 +2127,25 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 	int c;
 	int minimum, time;
 	ssize_t retval = 0;
-	ssize_t size;
 	long timeout;
 	unsigned long flags;
 	int packet;
 
-do_it_again:
 	c = job_control(tty, file);
 	if (c < 0)
 		return c;
 
+	/*
+	 *	Internal serialization of reads.
+	 */
+	if (file->f_flags & O_NONBLOCK) {
+		if (!mutex_trylock(&ldata->atomic_read_lock))
+			return -EAGAIN;
+	} else {
+		if (mutex_lock_interruptible(&ldata->atomic_read_lock))
+			return -ERESTARTSYS;
+	}
+
 	down_read(&tty->termios_rwsem);
 
 	minimum = time = 0;
@@ -2015,20 +2165,6 @@ do_it_again:
 		}
 	}
 
-	/*
-	 *	Internal serialization of reads.
-	 */
-	if (file->f_flags & O_NONBLOCK) {
-		if (!mutex_trylock(&ldata->atomic_read_lock)) {
-			up_read(&tty->termios_rwsem);
-			return -EAGAIN;
-		}
-	} else {
-		if (mutex_lock_interruptible(&ldata->atomic_read_lock)) {
-			up_read(&tty->termios_rwsem);
-			return -ERESTARTSYS;
-		}
-	}
 	packet = tty->packet;
 
 	add_wait_queue(&tty->read_wait, &wait);
@@ -2061,28 +2197,34 @@ do_it_again:
 
 		if (!input_available_p(tty, 0)) {
 			if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
-				retval = -EIO;
-				break;
-			}
-			if (tty_hung_up_p(file))
-				break;
-			if (!timeout)
-				break;
-			if (file->f_flags & O_NONBLOCK) {
-				retval = -EAGAIN;
-				break;
-			}
-			if (signal_pending(current)) {
-				retval = -ERESTARTSYS;
-				break;
-			}
-			n_tty_set_room(tty);
-			up_read(&tty->termios_rwsem);
+				up_read(&tty->termios_rwsem);
+				tty_flush_to_ldisc(tty);
+				down_read(&tty->termios_rwsem);
+				if (!input_available_p(tty, 0)) {
+					retval = -EIO;
+					break;
+				}
+			} else {
+				if (tty_hung_up_p(file))
+					break;
+				if (!timeout)
+					break;
+				if (file->f_flags & O_NONBLOCK) {
+					retval = -EAGAIN;
+					break;
+				}
+				if (signal_pending(current)) {
+					retval = -ERESTARTSYS;
+					break;
+				}
+				n_tty_set_room(tty);
+				up_read(&tty->termios_rwsem);
 
-			timeout = schedule_timeout(timeout);
+				timeout = schedule_timeout(timeout);
 
-			down_read(&tty->termios_rwsem);
-			continue;
+				down_read(&tty->termios_rwsem);
+				continue;
+			}
 		}
 		__set_current_state(TASK_RUNNING);
 
@@ -2098,7 +2240,10 @@ do_it_again:
 
 		if (ldata->icanon && !L_EXTPROC(tty)) {
 			retval = canon_copy_from_read_buf(tty, &b, &nr);
-			if (retval)
+			if (retval == -EAGAIN) {
+				retval = 0;
+				continue;
+			} else if (retval)
 				break;
 		} else {
 			int uncopied;
@@ -2119,25 +2264,19 @@ do_it_again:
 		if (time)
 			timeout = time;
 	}
-	mutex_unlock(&ldata->atomic_read_lock);
-	remove_wait_queue(&tty->read_wait, &wait);
+	n_tty_set_room(tty);
+	up_read(&tty->termios_rwsem);
 
+	remove_wait_queue(&tty->read_wait, &wait);
 	if (!waitqueue_active(&tty->read_wait))
 		ldata->minimum_to_wake = minimum;
 
+	mutex_unlock(&ldata->atomic_read_lock);
+
 	__set_current_state(TASK_RUNNING);
-	size = b - buf;
-	if (size) {
-		retval = size;
-		if (nr)
-			clear_bit(TTY_PUSH, &tty->flags);
-	} else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) {
-		up_read(&tty->termios_rwsem);
-		goto do_it_again;
-	}
+	if (b - buf)
+		retval = b - buf;
 
-	n_tty_set_room(tty);
-	up_read(&tty->termios_rwsem);
 	return retval;
 }
 
@@ -2215,8 +2354,12 @@ static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
 			if (tty->ops->flush_chars)
 				tty->ops->flush_chars(tty);
 		} else {
+			struct n_tty_data *ldata = tty->disc_data;
+
 			while (nr > 0) {
+				mutex_lock(&ldata->output_lock);
 				c = tty->ops->write(tty, b, nr);
+				mutex_unlock(&ldata->output_lock);
 				if (c < 0) {
 					retval = c;
 					goto break_out;
@@ -2270,7 +2413,7 @@ 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;