TTY: move ldisc data from tty_struct: read_* and echo_* and canon_* stuff

All the ring-buffers...

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 137 insertions, 123 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 702dd4adbdc..4794537a50f 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -83,6 +83,19 @@ struct n_tty_data {
 
 	DECLARE_BITMAP(process_char_map, 256);
 	DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
+
+	char *read_buf;
+	int read_head;
+	int read_tail;
+	int read_cnt;
+
+	unsigned char *echo_buf;
+	unsigned int echo_pos;
+	unsigned int echo_cnt;
+
+	int canon_data;
+	unsigned long canon_head;
+	unsigned int canon_column;
 };
 
 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
@@ -110,14 +123,14 @@ static void n_tty_set_room(struct tty_struct *tty)
 	int left;
 	int old_left;
 
-	/* tty->read_cnt is not read locked ? */
+	/* ldata->read_cnt is not read locked ? */
 	if (I_PARMRK(tty)) {
 		/* Multiply read_cnt by 3, since each byte might take up to
 		 * three times as many spaces when PARMRK is set (depending on
 		 * its flags, e.g. parity error). */
-		left = N_TTY_BUF_SIZE - tty->read_cnt * 3 - 1;
+		left = N_TTY_BUF_SIZE - ldata->read_cnt * 3 - 1;
 	} else
-		left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
+		left = N_TTY_BUF_SIZE - ldata->read_cnt - 1;
 
 	/*
 	 * If we are doing input canonicalization, and there are no
@@ -126,7 +139,7 @@ static void n_tty_set_room(struct tty_struct *tty)
 	 * characters will be beeped.
 	 */
 	if (left <= 0)
-		left = ldata->icanon && !tty->canon_data;
+		left = ldata->icanon && !ldata->canon_data;
 	old_left = tty->receive_room;
 	tty->receive_room = left;
 
@@ -137,10 +150,12 @@ static void n_tty_set_room(struct tty_struct *tty)
 
 static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
 {
-	if (tty->read_cnt < N_TTY_BUF_SIZE) {
-		tty->read_buf[tty->read_head] = c;
-		tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
-		tty->read_cnt++;
+	struct n_tty_data *ldata = tty->disc_data;
+
+	if (ldata->read_cnt < N_TTY_BUF_SIZE) {
+		ldata->read_buf[ldata->read_head] = c;
+		ldata->read_head = (ldata->read_head + 1) & (N_TTY_BUF_SIZE-1);
+		ldata->read_cnt++;
 	}
 }
 
@@ -198,14 +213,14 @@ static void reset_buffer_flags(struct tty_struct *tty)
 	unsigned long flags;
 
 	spin_lock_irqsave(&tty->read_lock, flags);
-	tty->read_head = tty->read_tail = tty->read_cnt = 0;
+	ldata->read_head = ldata->read_tail = ldata->read_cnt = 0;
 	spin_unlock_irqrestore(&tty->read_lock, flags);
 
 	mutex_lock(&tty->echo_lock);
-	tty->echo_pos = tty->echo_cnt = ldata->echo_overrun = 0;
+	ldata->echo_pos = ldata->echo_cnt = ldata->echo_overrun = 0;
 	mutex_unlock(&tty->echo_lock);
 
-	tty->canon_head = tty->canon_data = ldata->erasing = 0;
+	ldata->canon_head = ldata->canon_data = ldata->erasing = 0;
 	bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
 	n_tty_set_room(tty);
 }
@@ -257,11 +272,11 @@ static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
 
 	spin_lock_irqsave(&tty->read_lock, flags);
 	if (!ldata->icanon) {
-		n = tty->read_cnt;
-	} else if (tty->canon_data) {
-		n = (tty->canon_head > tty->read_tail) ?
-			tty->canon_head - tty->read_tail :
-			tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
+		n = ldata->read_cnt;
+	} else if (ldata->canon_data) {
+		n = (ldata->canon_head > ldata->read_tail) ?
+			ldata->canon_head - ldata->read_tail :
+			ldata->canon_head + (N_TTY_BUF_SIZE - ldata->read_tail);
 	}
 	spin_unlock_irqrestore(&tty->read_lock, flags);
 	return n;
@@ -331,11 +346,11 @@ static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
 		if (O_ONLCR(tty)) {
 			if (space < 2)
 				return -1;
-			tty->canon_column = ldata->column = 0;
+			ldata->canon_column = ldata->column = 0;
 			tty->ops->write(tty, "\r\n", 2);
 			return 2;
 		}
-		tty->canon_column = ldata->column;
+		ldata->canon_column = ldata->column;
 		break;
 	case '\r':
 		if (O_ONOCR(tty) && ldata->column == 0)
@@ -343,10 +358,10 @@ static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
 		if (O_OCRNL(tty)) {
 			c = '\n';
 			if (O_ONLRET(tty))
-				tty->canon_column = ldata->column = 0;
+				ldata->canon_column = ldata->column = 0;
 			break;
 		}
-		tty->canon_column = ldata->column = 0;
+		ldata->canon_column = ldata->column = 0;
 		break;
 	case '\t':
 		spaces = 8 - (ldata->column & 7);
@@ -453,14 +468,14 @@ static ssize_t process_output_block(struct tty_struct *tty,
 				ldata->column = 0;
 			if (O_ONLCR(tty))
 				goto break_out;
-			tty->canon_column = ldata->column;
+			ldata->canon_column = ldata->column;
 			break;
 		case '\r':
 			if (O_ONOCR(tty) && ldata->column == 0)
 				goto break_out;
 			if (O_OCRNL(tty))
 				goto break_out;
-			tty->canon_column = ldata->column = 0;
+			ldata->canon_column = ldata->column = 0;
 			break;
 		case '\t':
 			goto break_out;
@@ -518,7 +533,7 @@ static void process_echoes(struct tty_struct *tty)
 	unsigned char c;
 	unsigned char *cp, *buf_end;
 
-	if (!tty->echo_cnt)
+	if (!ldata->echo_cnt)
 		return;
 
 	mutex_lock(&tty->output_lock);
@@ -526,9 +541,9 @@ static void process_echoes(struct tty_struct *tty)
 
 	space = tty_write_room(tty);
 
-	buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
-	cp = tty->echo_buf + tty->echo_pos;
-	nr = tty->echo_cnt;
+	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;
 		if (c == ECHO_OP_START) {
@@ -565,7 +580,7 @@ static void process_echoes(struct tty_struct *tty)
 				 * Otherwise, tab spacing is normal.
 				 */
 				if (!(num_chars & 0x80))
-					num_chars += tty->canon_column;
+					num_chars += ldata->canon_column;
 				num_bs = 8 - (num_chars & 7);
 
 				if (num_bs > space) {
@@ -583,7 +598,7 @@ static void process_echoes(struct tty_struct *tty)
 				break;
 
 			case ECHO_OP_SET_CANON_COL:
-				tty->canon_column = ldata->column;
+				ldata->canon_column = ldata->column;
 				cp += 2;
 				nr -= 2;
 				break;
@@ -655,14 +670,14 @@ static void process_echoes(struct tty_struct *tty)
 	}
 
 	if (nr == 0) {
-		tty->echo_pos = 0;
-		tty->echo_cnt = 0;
+		ldata->echo_pos = 0;
+		ldata->echo_cnt = 0;
 		ldata->echo_overrun = 0;
 	} else {
-		int num_processed = tty->echo_cnt - nr;
-		tty->echo_pos += num_processed;
-		tty->echo_pos &= N_TTY_BUF_SIZE - 1;
-		tty->echo_cnt = nr;
+		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;
 	}
@@ -689,37 +704,37 @@ static void add_echo_byte(unsigned char c, struct tty_struct *tty)
 	struct n_tty_data *ldata = tty->disc_data;
 	int	new_byte_pos;
 
-	if (tty->echo_cnt == N_TTY_BUF_SIZE) {
+	if (ldata->echo_cnt == N_TTY_BUF_SIZE) {
 		/* Circular buffer is already at capacity */
-		new_byte_pos = tty->echo_pos;
+		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 (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
-			if (tty->echo_buf[(tty->echo_pos + 1) &
+		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) {
-				tty->echo_pos += 3;
-				tty->echo_cnt -= 2;
+				ldata->echo_pos += 3;
+				ldata->echo_cnt -= 2;
 			} else {
-				tty->echo_pos += 2;
-				tty->echo_cnt -= 1;
+				ldata->echo_pos += 2;
+				ldata->echo_cnt -= 1;
 			}
 		} else {
-			tty->echo_pos++;
+			ldata->echo_pos++;
 		}
-		tty->echo_pos &= N_TTY_BUF_SIZE - 1;
+		ldata->echo_pos &= N_TTY_BUF_SIZE - 1;
 
 		ldata->echo_overrun = 1;
 	} else {
-		new_byte_pos = tty->echo_pos + tty->echo_cnt;
+		new_byte_pos = ldata->echo_pos + ldata->echo_cnt;
 		new_byte_pos &= N_TTY_BUF_SIZE - 1;
-		tty->echo_cnt++;
+		ldata->echo_cnt++;
 	}
 
-	tty->echo_buf[new_byte_pos] = c;
+	ldata->echo_buf[new_byte_pos] = c;
 }
 
 /**
@@ -889,7 +904,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 	unsigned long flags;
 
 	/* FIXME: locking needed ? */
-	if (tty->read_head == tty->canon_head) {
+	if (ldata->read_head == ldata->canon_head) {
 		/* process_output('\a', tty); */ /* what do you think? */
 		return;
 	}
@@ -900,17 +915,17 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 	else {
 		if (!L_ECHO(tty)) {
 			spin_lock_irqsave(&tty->read_lock, flags);
-			tty->read_cnt -= ((tty->read_head - tty->canon_head) &
+			ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) &
 					  (N_TTY_BUF_SIZE - 1));
-			tty->read_head = tty->canon_head;
+			ldata->read_head = ldata->canon_head;
 			spin_unlock_irqrestore(&tty->read_lock, flags);
 			return;
 		}
 		if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
 			spin_lock_irqsave(&tty->read_lock, flags);
-			tty->read_cnt -= ((tty->read_head - tty->canon_head) &
+			ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) &
 					  (N_TTY_BUF_SIZE - 1));
-			tty->read_head = tty->canon_head;
+			ldata->read_head = ldata->canon_head;
 			spin_unlock_irqrestore(&tty->read_lock, flags);
 			finish_erasing(tty);
 			echo_char(KILL_CHAR(tty), tty);
@@ -924,14 +939,14 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 
 	seen_alnums = 0;
 	/* FIXME: Locking ?? */
-	while (tty->read_head != tty->canon_head) {
-		head = tty->read_head;
+	while (ldata->read_head != ldata->canon_head) {
+		head = ldata->read_head;
 
 		/* erase a single possibly multibyte character */
 		do {
 			head = (head - 1) & (N_TTY_BUF_SIZE-1);
-			c = tty->read_buf[head];
-		} while (is_continuation(c, tty) && head != tty->canon_head);
+			c = ldata->read_buf[head];
+		} while (is_continuation(c, tty) && head != ldata->canon_head);
 
 		/* do not partially erase */
 		if (is_continuation(c, tty))
@@ -944,10 +959,10 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 			else if (seen_alnums)
 				break;
 		}
-		cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
+		cnt = (ldata->read_head - head) & (N_TTY_BUF_SIZE-1);
 		spin_lock_irqsave(&tty->read_lock, flags);
-		tty->read_head = head;
-		tty->read_cnt -= cnt;
+		ldata->read_head = head;
+		ldata->read_cnt -= cnt;
 		spin_unlock_irqrestore(&tty->read_lock, flags);
 		if (L_ECHO(tty)) {
 			if (L_ECHOPRT(tty)) {
@@ -959,7 +974,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 				echo_char(c, tty);
 				while (--cnt > 0) {
 					head = (head+1) & (N_TTY_BUF_SIZE-1);
-					echo_char_raw(tty->read_buf[head], tty);
+					echo_char_raw(ldata->read_buf[head], tty);
 					echo_move_back_col(tty);
 				}
 			} else if (kill_type == ERASE && !L_ECHOE(tty)) {
@@ -967,7 +982,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 			} else if (c == '\t') {
 				unsigned int num_chars = 0;
 				int after_tab = 0;
-				unsigned long tail = tty->read_head;
+				unsigned long tail = ldata->read_head;
 
 				/*
 				 * Count the columns used for characters
@@ -976,9 +991,9 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 				 * This info is used to go back the correct
 				 * number of columns.
 				 */
-				while (tail != tty->canon_head) {
+				while (tail != ldata->canon_head) {
 					tail = (tail-1) & (N_TTY_BUF_SIZE-1);
-					c = tty->read_buf[tail];
+					c = ldata->read_buf[tail];
 					if (c == '\t') {
 						after_tab = 1;
 						break;
@@ -1006,7 +1021,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
 		if (kill_type == ERASE)
 			break;
 	}
-	if (tty->read_head == tty->canon_head && L_ECHO(tty))
+	if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
 		finish_erasing(tty);
 }
 
@@ -1171,7 +1186,7 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 	if (!test_bit(c, ldata->process_char_map) || ldata->lnext) {
 		ldata->lnext = 0;
 		parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-		if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
+		if (ldata->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
 			/* beep if no space */
 			if (L_ECHO(tty))
 				process_output('\a', tty);
@@ -1180,7 +1195,7 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
 		if (L_ECHO(tty)) {
 			finish_erasing(tty);
 			/* Record the column of first canon char. */
-			if (tty->canon_head == tty->read_head)
+			if (ldata->canon_head == ldata->read_head)
 				echo_set_canon_col(tty);
 			echo_char(c, tty);
 			process_echoes(tty);
@@ -1264,20 +1279,20 @@ send_signal:
 		}
 		if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
 		    L_IEXTEN(tty)) {
-			unsigned long tail = tty->canon_head;
+			unsigned long tail = ldata->canon_head;
 
 			finish_erasing(tty);
 			echo_char(c, tty);
 			echo_char_raw('\n', tty);
-			while (tail != tty->read_head) {
-				echo_char(tty->read_buf[tail], tty);
+			while (tail != ldata->read_head) {
+				echo_char(ldata->read_buf[tail], tty);
 				tail = (tail+1) & (N_TTY_BUF_SIZE-1);
 			}
 			process_echoes(tty);
 			return;
 		}
 		if (c == '\n') {
-			if (tty->read_cnt >= N_TTY_BUF_SIZE) {
+			if (ldata->read_cnt >= N_TTY_BUF_SIZE) {
 				if (L_ECHO(tty))
 					process_output('\a', tty);
 				return;
@@ -1289,9 +1304,9 @@ send_signal:
 			goto handle_newline;
 		}
 		if (c == EOF_CHAR(tty)) {
-			if (tty->read_cnt >= N_TTY_BUF_SIZE)
+			if (ldata->read_cnt >= N_TTY_BUF_SIZE)
 				return;
-			if (tty->canon_head != tty->read_head)
+			if (ldata->canon_head != ldata->read_head)
 				set_bit(TTY_PUSH, &tty->flags);
 			c = __DISABLED_CHAR;
 			goto handle_newline;
@@ -1300,7 +1315,7 @@ send_signal:
 		    (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
 			parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
 				 ? 1 : 0;
-			if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
+			if (ldata->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
 				if (L_ECHO(tty))
 					process_output('\a', tty);
 				return;
@@ -1310,7 +1325,7 @@ send_signal:
 			 */
 			if (L_ECHO(tty)) {
 				/* Record the column of first canon char. */
-				if (tty->canon_head == tty->read_head)
+				if (ldata->canon_head == ldata->read_head)
 					echo_set_canon_col(tty);
 				echo_char(c, tty);
 				process_echoes(tty);
@@ -1324,10 +1339,10 @@ send_signal:
 
 handle_newline:
 			spin_lock_irqsave(&tty->read_lock, flags);
-			set_bit(tty->read_head, ldata->read_flags);
+			set_bit(ldata->read_head, ldata->read_flags);
 			put_tty_queue_nolock(c, tty);
-			tty->canon_head = tty->read_head;
-			tty->canon_data++;
+			ldata->canon_head = ldata->read_head;
+			ldata->canon_data++;
 			spin_unlock_irqrestore(&tty->read_lock, flags);
 			kill_fasync(&tty->fasync, SIGIO, POLL_IN);
 			if (waitqueue_active(&tty->read_wait))
@@ -1337,7 +1352,7 @@ handle_newline:
 	}
 
 	parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-	if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
+	if (ldata->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
 		/* beep if no space */
 		if (L_ECHO(tty))
 			process_output('\a', tty);
@@ -1349,7 +1364,7 @@ handle_newline:
 			echo_char_raw('\n', tty);
 		else {
 			/* Record the column of first canon char. */
-			if (tty->canon_head == tty->read_head)
+			if (ldata->canon_head == ldata->read_head)
 				echo_set_canon_col(tty);
 			echo_char(c, tty);
 		}
@@ -1403,21 +1418,21 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 
 	if (ldata->real_raw) {
 		spin_lock_irqsave(&tty->read_lock, cpuflags);
-		i = min(N_TTY_BUF_SIZE - tty->read_cnt,
-			N_TTY_BUF_SIZE - tty->read_head);
+		i = min(N_TTY_BUF_SIZE - ldata->read_cnt,
+			N_TTY_BUF_SIZE - ldata->read_head);
 		i = min(count, i);
-		memcpy(tty->read_buf + tty->read_head, cp, i);
-		tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
-		tty->read_cnt += i;
+		memcpy(ldata->read_buf + ldata->read_head, cp, i);
+		ldata->read_head = (ldata->read_head + i) & (N_TTY_BUF_SIZE-1);
+		ldata->read_cnt += i;
 		cp += i;
 		count -= i;
 
-		i = min(N_TTY_BUF_SIZE - tty->read_cnt,
-			N_TTY_BUF_SIZE - tty->read_head);
+		i = min(N_TTY_BUF_SIZE - ldata->read_cnt,
+			N_TTY_BUF_SIZE - ldata->read_head);
 		i = min(count, i);
-		memcpy(tty->read_buf + tty->read_head, cp, i);
-		tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
-		tty->read_cnt += i;
+		memcpy(ldata->read_buf + ldata->read_head, cp, i);
+		ldata->read_head = (ldata->read_head + i) & (N_TTY_BUF_SIZE-1);
+		ldata->read_cnt += i;
 		spin_unlock_irqrestore(&tty->read_lock, cpuflags);
 	} else {
 		for (i = count, p = cp, f = fp; i; i--, p++) {
@@ -1449,7 +1464,7 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 
 	n_tty_set_room(tty);
 
-	if ((!ldata->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
+	if ((!ldata->icanon && (ldata->read_cnt >= tty->minimum_to_wake)) ||
 		L_EXTPROC(tty)) {
 		kill_fasync(&tty->fasync, SIGIO, POLL_IN);
 		if (waitqueue_active(&tty->read_wait))
@@ -1500,12 +1515,12 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
 		canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
 	if (canon_change) {
 		bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
-		tty->canon_head = tty->read_tail;
-		tty->canon_data = 0;
+		ldata->canon_head = ldata->read_tail;
+		ldata->canon_data = 0;
 		ldata->erasing = 0;
 	}
 
-	if (canon_change && !L_ICANON(tty) && tty->read_cnt)
+	if (canon_change && !L_ICANON(tty) && ldata->read_cnt)
 		wake_up_interruptible(&tty->read_wait);
 
 	ldata->icanon = (L_ICANON(tty) != 0);
@@ -1586,11 +1601,9 @@ static void n_tty_close(struct tty_struct *tty)
 	struct n_tty_data *ldata = tty->disc_data;
 
 	n_tty_flush_buffer(tty);
-	kfree(tty->read_buf);
-	kfree(tty->echo_buf);
+	kfree(ldata->read_buf);
+	kfree(ldata->echo_buf);
 	kfree(ldata);
-	tty->read_buf = NULL;
-	tty->echo_buf = NULL;
 	tty->disc_data = NULL;
 }
 
@@ -1615,9 +1628,9 @@ static int n_tty_open(struct tty_struct *tty)
 	ldata->overrun_time = jiffies;
 
 	/* These are ugly. Currently a malloc failure here can panic */
-	tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
-	tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
-	if (!tty->read_buf || !tty->echo_buf)
+	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;
@@ -1630,8 +1643,8 @@ static int n_tty_open(struct tty_struct *tty)
 
 	return 0;
 err_free_bufs:
-	kfree(tty->read_buf);
-	kfree(tty->echo_buf);
+	kfree(ldata->read_buf);
+	kfree(ldata->echo_buf);
 	kfree(ldata);
 err:
 	return -ENOMEM;
@@ -1643,9 +1656,9 @@ static inline int input_available_p(struct tty_struct *tty, int amt)
 
 	tty_flush_to_ldisc(tty);
 	if (ldata->icanon && !L_EXTPROC(tty)) {
-		if (tty->canon_data)
+		if (ldata->canon_data)
 			return 1;
-	} else if (tty->read_cnt >= (amt ? amt : 1))
+	} else if (ldata->read_cnt >= (amt ? amt : 1))
 		return 1;
 
 	return 0;
@@ -1681,21 +1694,21 @@ static int copy_from_read_buf(struct tty_struct *tty,
 
 	retval = 0;
 	spin_lock_irqsave(&tty->read_lock, flags);
-	n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
+	n = min(ldata->read_cnt, N_TTY_BUF_SIZE - ldata->read_tail);
 	n = min(*nr, n);
 	spin_unlock_irqrestore(&tty->read_lock, flags);
 	if (n) {
-		retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
+		retval = copy_to_user(*b, &ldata->read_buf[ldata->read_tail], n);
 		n -= retval;
 		is_eof = n == 1 &&
-			tty->read_buf[tty->read_tail] == EOF_CHAR(tty);
-		tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n,
+			ldata->read_buf[ldata->read_tail] == EOF_CHAR(tty);
+		tty_audit_add_data(tty, &ldata->read_buf[ldata->read_tail], n,
 				ldata->icanon);
 		spin_lock_irqsave(&tty->read_lock, flags);
-		tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
-		tty->read_cnt -= n;
+		ldata->read_tail = (ldata->read_tail + n) & (N_TTY_BUF_SIZE-1);
+		ldata->read_cnt -= n;
 		/* Turn single EOF into zero-length read */
-		if (L_EXTPROC(tty) && ldata->icanon && is_eof && !tty->read_cnt)
+		if (L_EXTPROC(tty) && ldata->icanon && is_eof && !ldata->read_cnt)
 			n = 0;
 		spin_unlock_irqrestore(&tty->read_lock, flags);
 		*b += n;
@@ -1878,22 +1891,22 @@ do_it_again:
 		if (ldata->icanon && !L_EXTPROC(tty)) {
 			/* N.B. avoid overrun if nr == 0 */
 			spin_lock_irqsave(&tty->read_lock, flags);
-			while (nr && tty->read_cnt) {
+			while (nr && ldata->read_cnt) {
 				int eol;
 
-				eol = test_and_clear_bit(tty->read_tail,
+				eol = test_and_clear_bit(ldata->read_tail,
 						ldata->read_flags);
-				c = tty->read_buf[tty->read_tail];
-				tty->read_tail = ((tty->read_tail+1) &
+				c = ldata->read_buf[ldata->read_tail];
+				ldata->read_tail = ((ldata->read_tail+1) &
 						  (N_TTY_BUF_SIZE-1));
-				tty->read_cnt--;
+				ldata->read_cnt--;
 				if (eol) {
 					/* this test should be redundant:
 					 * we shouldn't be reading data if
 					 * canon_data is 0
 					 */
-					if (--tty->canon_data < 0)
-						tty->canon_data = 0;
+					if (--ldata->canon_data < 0)
+						ldata->canon_data = 0;
 				}
 				spin_unlock_irqrestore(&tty->read_lock, flags);
 
@@ -2111,15 +2124,15 @@ static unsigned long inq_canon(struct tty_struct *tty)
 	struct n_tty_data *ldata = tty->disc_data;
 	int nr, head, tail;
 
-	if (!tty->canon_data)
+	if (!ldata->canon_data)
 		return 0;
-	head = tty->canon_head;
-	tail = tty->read_tail;
+	head = ldata->canon_head;
+	tail = ldata->read_tail;
 	nr = (head - tail) & (N_TTY_BUF_SIZE-1);
 	/* Skip EOF-chars.. */
 	while (head != tail) {
 		if (test_bit(tail, ldata->read_flags) &&
-		    tty->read_buf[tail] == __DISABLED_CHAR)
+		    ldata->read_buf[tail] == __DISABLED_CHAR)
 			nr--;
 		tail = (tail+1) & (N_TTY_BUF_SIZE-1);
 	}
@@ -2129,6 +2142,7 @@ static unsigned long inq_canon(struct tty_struct *tty)
 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
 		       unsigned int cmd, unsigned long arg)
 {
+	struct n_tty_data *ldata = tty->disc_data;
 	int retval;
 
 	switch (cmd) {
@@ -2136,7 +2150,7 @@ static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
 		return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
 	case TIOCINQ:
 		/* FIXME: Locking */
-		retval = tty->read_cnt;
+		retval = ldata->read_cnt;
 		if (L_ICANON(tty))
 			retval = inq_canon(tty);
 		return put_user(retval, (unsigned int __user *) arg);