epoll keyed wakeups: make tty use keyed wakeups

Introduce keyed event wakeups inside the TTY code.
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: William Lee Irwin III <wli@movementarian.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_io.c

@@ -464,7 +464,7 @@ void tty_wakeup(struct tty_struct *tty)
 			tty_ldisc_deref(ld);
 		}
 	}
-	wake_up_interruptible(&tty->write_wait);
+	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
 }
 
 EXPORT_SYMBOL_GPL(tty_wakeup);
@@ -587,8 +587,8 @@ static void do_tty_hangup(struct work_struct *work)
 	 * FIXME: Once we trust the LDISC code better we can wait here for
 	 * ldisc completion and fix the driver call race
 	 */
-	wake_up_interruptible(&tty->write_wait);
-	wake_up_interruptible(&tty->read_wait);
+	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
+	wake_up_interruptible_poll(&tty->read_wait, POLLIN);
 	/*
 	 * Shutdown the current line discipline, and reset it to
 	 * N_TTY.
@@ -879,7 +879,7 @@ void stop_tty(struct tty_struct *tty)
 	if (tty->link && tty->link->packet) {
 		tty->ctrl_status &= ~TIOCPKT_START;
 		tty->ctrl_status |= TIOCPKT_STOP;
-		wake_up_interruptible(&tty->link->read_wait);
+		wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 	}
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 	if (tty->ops->stop)
@@ -913,7 +913,7 @@ void start_tty(struct tty_struct *tty)
 	if (tty->link && tty->link->packet) {
 		tty->ctrl_status &= ~TIOCPKT_STOP;
 		tty->ctrl_status |= TIOCPKT_START;
-		wake_up_interruptible(&tty->link->read_wait);
+		wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
 	}
 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 	if (tty->ops->start)
@@ -970,7 +970,7 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
 void tty_write_unlock(struct tty_struct *tty)
 {
 	mutex_unlock(&tty->atomic_write_lock);
-	wake_up_interruptible(&tty->write_wait);
+	wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
 }
 
 int tty_write_lock(struct tty_struct *tty, int ndelay)
@@ -1623,21 +1623,21 @@ void tty_release_dev(struct file *filp)
 
 		if (tty_closing) {
 			if (waitqueue_active(&tty->read_wait)) {
-				wake_up(&tty->read_wait);
+				wake_up_poll(&tty->read_wait, POLLIN);
 				do_sleep++;
 			}
 			if (waitqueue_active(&tty->write_wait)) {
-				wake_up(&tty->write_wait);
+				wake_up_poll(&tty->write_wait, POLLOUT);
 				do_sleep++;
 			}
 		}
 		if (o_tty_closing) {
 			if (waitqueue_active(&o_tty->read_wait)) {
-				wake_up(&o_tty->read_wait);
+				wake_up_poll(&o_tty->read_wait, POLLIN);
 				do_sleep++;
 			}
 			if (waitqueue_active(&o_tty->write_wait)) {
-				wake_up(&o_tty->write_wait);
+				wake_up_poll(&o_tty->write_wait, POLLOUT);
 				do_sleep++;
 			}
 		}