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 702dd4adbdc9..4794537a50ff 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);