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, 8 insertions, 7 deletions

diff --git a/drivers/isdn/gigaset/ser-gigaset.c b/drivers/isdn/gigaset/ser-gigaset.c
index fceeb1d57682..45d1ee93cd39 100644
--- a/drivers/isdn/gigaset/ser-gigaset.c
+++ b/drivers/isdn/gigaset/ser-gigaset.c
@@ -68,10 +68,10 @@ static int write_modem(struct cardstate *cs)
         struct tty_struct *tty = cs->hw.ser->tty;
         struct bc_state *bcs = &cs->bcs[0];     /* only one channel */
         struct sk_buff *skb = bcs->tx_skb;
-        int sent;
+        int sent = -EOPNOTSUPP;
 
         if (!tty || !tty->driver || !skb)
-                return -EFAULT;
+                return -EINVAL;
 
         if (!skb->len) {
                 dev_kfree_skb_any(skb);
@@ -80,7 +80,8 @@ static int write_modem(struct cardstate *cs)
         }
 
         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-        sent = tty->driver->write(tty, skb->data, skb->len);
+        if (tty->ops->write)
+                sent = tty->ops->write(tty, skb->data, skb->len);
         gig_dbg(DEBUG_OUTPUT, "write_modem: sent %d", sent);
         if (sent < 0) {
                 /* error */
@@ -120,7 +121,7 @@ static int send_cb(struct cardstate *cs)
 
         if (cb->len) {
                 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-                sent = tty->driver->write(tty, cb->buf + cb->offset, cb->len);
+                sent = tty->ops->write(tty, cb->buf + cb->offset, cb->len);
                 if (sent < 0) {
                         /* error */
                         gig_dbg(DEBUG_OUTPUT, "send_cb: write error %d", sent);
@@ -440,14 +441,14 @@ static int gigaset_set_modem_ctrl(struct cardstate *cs, unsigned old_state, unsi
         struct tty_struct *tty = cs->hw.ser->tty;
         unsigned int set, clear;
 
-        if (!tty || !tty->driver || !tty->driver->tiocmset)
-                return -EFAULT;
+        if (!tty || !tty->driver || !tty->ops->tiocmset)
+                return -EINVAL;
         set = new_state & ~old_state;
         clear = old_state & ~new_state;
         if (!set && !clear)
                 return 0;
         gig_dbg(DEBUG_IF, "tiocmset set %x clear %x", set, clear);
-        return tty->driver->tiocmset(tty, NULL, set, clear);
+        return tty->ops->tiocmset(tty, NULL, set, clear);
 }
 
 static int gigaset_baud_rate(struct cardstate *cs, unsigned cflag)