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, 4 insertions, 7 deletions

diff --git a/drivers/char/n_hdlc.c b/drivers/char/n_hdlc.c
index a07c0af4819..a35bfd7ee80 100644
--- a/drivers/char/n_hdlc.c
+++ b/drivers/char/n_hdlc.c
@@ -342,12 +342,10 @@ static int n_hdlc_tty_open (struct tty_struct *tty)
 #endif
         
         /* Flush any pending characters in the driver and discipline. */
-        
         if (tty->ldisc.flush_buffer)
-                tty->ldisc.flush_buffer (tty);
+                tty->ldisc.flush_buffer(tty);
 
-        if (tty->driver->flush_buffer)
-                tty->driver->flush_buffer (tty);
+        tty_driver_flush_buffer(tty);
                 
         if (debuglevel >= DEBUG_LEVEL_INFO)     
                 printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
@@ -399,7 +397,7 @@ static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
                         
                 /* Send the next block of data to device */
                 tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
-                actual = tty->driver->write(tty, tbuf->buf, tbuf->count);
+                actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
 
                 /* rollback was possible and has been done */
                 if (actual == -ERESTARTSYS) {
@@ -752,8 +750,7 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
 
         case TIOCOUTQ:
                 /* get the pending tx byte count in the driver */
-                count = tty->driver->chars_in_buffer ?
-                                tty->driver->chars_in_buffer(tty) : 0;
+                count = tty_chars_in_buffer(tty);
                 /* add size of next output frame in queue */
                 spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags);
                 if (n_hdlc->tx_buf_list.head)