tty: The big operations rework

- Operations are now a shared const function block as with most other Linux
  objects

- Introduce wrappers for some optional functions to get consistent behaviour

- Wrap put_char which used to be patched by the tty layer

- Document which functions are needed/optional

- Make put_char report success/fail

- Cache the driver->ops pointer in the tty as tty->ops

- Remove various surplus lock calls we no longer need

- Remove proc_write method as noted by Alexey Dobriyan

- Introduce some missing sanity checks where certain driver/ldisc
  combinations would oops as they didn't check needed methods were present

[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 43 insertions, 60 deletions

diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index e1518e17e09d..abc93a93dcdd 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -149,8 +149,8 @@ static void check_unthrottle(struct tty_struct *tty)
 {
         if (tty->count &&
             test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
-            tty->driver->unthrottle)
-                tty->driver->unthrottle(tty);
+            tty->ops->unthrottle)
+                tty->ops->unthrottle(tty);
 }
 
 /**
@@ -273,7 +273,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
 {
         int     space, spaces;
 
-        space = tty->driver->write_room(tty);
+        space = tty_write_room(tty);
         if (!space)
                 return -1;
 
@@ -286,7 +286,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
                         if (O_ONLCR(tty)) {
                                 if (space < 2)
                                         return -1;
-                                tty->driver->put_char(tty, '\r');
+                                tty_put_char(tty, '\r');
                                 tty->column = 0;
                         }
                         tty->canon_column = tty->column;
@@ -308,7 +308,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
                                 if (space < spaces)
                                         return -1;
                                 tty->column += spaces;
-                                tty->driver->write(tty, "        ", spaces);
+                                tty->ops->write(tty, "        ", spaces);
                                 return 0;
                         }
                         tty->column += spaces;
@@ -325,7 +325,7 @@ static int opost(unsigned char c, struct tty_struct *tty)
                         break;
                 }
         }
-        tty->driver->put_char(tty, c);
+        tty_put_char(tty, c);
         unlock_kernel();
         return 0;
 }
@@ -352,7 +352,7 @@ static ssize_t opost_block(struct tty_struct *tty,
         int     i;
         const unsigned char *cp;
 
-        space = tty->driver->write_room(tty);
+        space = tty_write_room(tty);
         if (!space)
                 return 0;
         if (nr > space)
@@ -390,28 +390,15 @@ static ssize_t opost_block(struct tty_struct *tty,
                 }
         }
 break_out:
-        if (tty->driver->flush_chars)
-                tty->driver->flush_chars(tty);
-        i = tty->driver->write(tty, buf, i);
+        if (tty->ops->flush_chars)
+                tty->ops->flush_chars(tty);
+        i = tty->ops->write(tty, buf, i);
         unlock_kernel();
         return i;
 }
 
 
 /**
- *      put_char        -       write character to driver
- *      @c: character (or part of unicode symbol)
- *      @tty: terminal device
- *
- *      Queue a byte to the driver layer for output
- */
-
-static inline void put_char(unsigned char c, struct tty_struct *tty)
-{
-        tty->driver->put_char(tty, c);
-}
-
-/**
  *      echo_char       -       echo characters
  *      @c: unicode byte to echo
  *      @tty: terminal device
@@ -423,8 +410,8 @@ static inline void put_char(unsigned char c, struct tty_struct *tty)
 static void echo_char(unsigned char c, struct tty_struct *tty)
 {
         if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
-                put_char('^', tty);
-                put_char(c ^ 0100, tty);
+                tty_put_char(tty, '^');
+                tty_put_char(tty, c ^ 0100);
                 tty->column += 2;
         } else
                 opost(c, tty);
@@ -433,7 +420,7 @@ static void echo_char(unsigned char c, struct tty_struct *tty)
 static inline void finish_erasing(struct tty_struct *tty)
 {
         if (tty->erasing) {
-                put_char('/', tty);
+                tty_put_char(tty, '/');
                 tty->column++;
                 tty->erasing = 0;
         }
@@ -517,7 +504,7 @@ static void eraser(unsigned char c, struct tty_struct *tty)
                 if (L_ECHO(tty)) {
                         if (L_ECHOPRT(tty)) {
                                 if (!tty->erasing) {
-                                        put_char('\\', tty);
+                                        tty_put_char(tty, '\\');
                                         tty->column++;
                                         tty->erasing = 1;
                                 }
@@ -525,7 +512,7 @@ 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);
-                                        put_char(tty->read_buf[head], tty);
+                                        tty_put_char(tty, tty->read_buf[head]);
                                 }
                         } else if (kill_type == ERASE && !L_ECHOE(tty)) {
                                 echo_char(ERASE_CHAR(tty), tty);
@@ -553,22 +540,22 @@ static void eraser(unsigned char c, struct tty_struct *tty)
                                 /* Now backup to that column. */
                                 while (tty->column > col) {
                                         /* Can't use opost here. */
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '\b');
                                         if (tty->column > 0)
                                                 tty->column--;
                                 }
                         } else {
                                 if (iscntrl(c) && L_ECHOCTL(tty)) {
-                                        put_char('\b', tty);
-                                        put_char(' ', tty);
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '\b');
+                                        tty_put_char(tty, ' ');
+                                        tty_put_char(tty, '\b');
                                         if (tty->column > 0)
                                                 tty->column--;
                                 }
                                 if (!iscntrl(c) || L_ECHOCTL(tty)) {
-                                        put_char('\b', tty);
-                                        put_char(' ', tty);
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '\b');
+                                        tty_put_char(tty, ' ');
+                                        tty_put_char(tty, '\b');
                                         if (tty->column > 0)
                                                 tty->column--;
                                 }
@@ -599,8 +586,7 @@ static inline void isig(int sig, struct tty_struct *tty, int flush)
                 kill_pgrp(tty->pgrp, sig, 1);
         if (flush || !L_NOFLSH(tty)) {
                 n_tty_flush_buffer(tty);
-                if (tty->driver->flush_buffer)
-                        tty->driver->flush_buffer(tty);
+                tty_driver_flush_buffer(tty);
         }
 }
 
@@ -732,7 +718,7 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
                 tty->lnext = 0;
                 if (L_ECHO(tty)) {
                         if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
-                                put_char('\a', tty); /* beep if no space */
+                                tty_put_char(tty, '\a'); /* beep if no space */
                                 return;
                         }
                         /* Record the column of first canon char. */
@@ -776,8 +762,7 @@ send_signal:
                          */
                         if (!L_NOFLSH(tty)) {
                                 n_tty_flush_buffer(tty);
-                                if (tty->driver->flush_buffer)
-                                        tty->driver->flush_buffer(tty);
+                                tty_driver_flush_buffer(tty);
                         }
                         if (L_ECHO(tty))
                                 echo_char(c, tty);
@@ -806,8 +791,8 @@ send_signal:
                         if (L_ECHO(tty)) {
                                 finish_erasing(tty);
                                 if (L_ECHOCTL(tty)) {
-                                        put_char('^', tty);
-                                        put_char('\b', tty);
+                                        tty_put_char(tty, '^');
+                                        tty_put_char(tty, '\b');
                                 }
                         }
                         return;
@@ -828,7 +813,7 @@ send_signal:
                 if (c == '\n') {
                         if (L_ECHO(tty) || L_ECHONL(tty)) {
                                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
-                                        put_char('\a', tty);
+                                        tty_put_char(tty, '\a');
                                 opost('\n', tty);
                         }
                         goto handle_newline;
@@ -846,7 +831,7 @@ send_signal:
                          */
                         if (L_ECHO(tty)) {
                                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
-                                        put_char('\a', tty);
+                                        tty_put_char(tty, '\a');
                                 /* Record the column of first canon char. */
                                 if (tty->canon_head == tty->read_head)
                                         tty->canon_column = tty->column;
@@ -876,7 +861,7 @@ handle_newline:
         finish_erasing(tty);
         if (L_ECHO(tty)) {
                 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
-                        put_char('\a', tty); /* beep if no space */
+                        tty_put_char(tty, '\a'); /* beep if no space */
                         return;
                 }
                 if (c == '\n')
@@ -980,8 +965,8 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
                                 break;
                         }
                 }
-                if (tty->driver->flush_chars)
-                        tty->driver->flush_chars(tty);
+                if (tty->ops->flush_chars)
+                        tty->ops->flush_chars(tty);
         }
 
         n_tty_set_room(tty);
@@ -1000,8 +985,8 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
         if (tty->receive_room < TTY_THRESHOLD_THROTTLE) {
                 /* check TTY_THROTTLED first so it indicates our state */
                 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
-                    tty->driver->throttle)
-                        tty->driver->throttle(tty);
+                    tty->ops->throttle)
+                        tty->ops->throttle(tty);
         }
 }
 
@@ -1086,6 +1071,9 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
                         tty->real_raw = 0;
         }
         n_tty_set_room(tty);
+        /* The termios change make the tty ready for I/O */
+        wake_up_interruptible(&tty->write_wait);
+        wake_up_interruptible(&tty->read_wait);
 }
 
 /**
@@ -1513,11 +1501,11 @@ static ssize_t write_chan(struct tty_struct *tty, struct file *file,
                                         break;
                                 b++; nr--;
                         }
-                        if (tty->driver->flush_chars)
-                                tty->driver->flush_chars(tty);
+                        if (tty->ops->flush_chars)
+                                tty->ops->flush_chars(tty);
                 } else {
                         while (nr > 0) {
-                                c = tty->driver->write(tty, b, nr);
+                                c = tty->ops->write(tty, b, nr);
                                 if (c < 0) {
                                         retval = c;
                                         goto break_out;
@@ -1554,11 +1542,6 @@ break_out:
  *
  *      This code must be sure never to sleep through a hangup.
  *      Called without the kernel lock held - fine
- *
- *      FIXME: if someone changes the VMIN or discipline settings for the
- *      terminal while another process is in poll() the poll does not
- *      recompute the new limits. Possibly set_termios should issue
- *      a read wakeup to fix this bug.
  */
 
 static unsigned int normal_poll(struct tty_struct *tty, struct file *file,
@@ -1582,9 +1565,9 @@ static unsigned int normal_poll(struct tty_struct *tty, struct file *file,
                 else
                         tty->minimum_to_wake = 1;
         }
-        if (!tty_is_writelocked(tty) &&
-                        tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
-                        tty->driver->write_room(tty) > 0)
+        if (tty->ops->write && !tty_is_writelocked(tty) &&
+                        tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
+                        tty_write_room(tty) > 0)
                 mask |= POLLOUT | POLLWRNORM;
         return mask;
 }