MFC: r294362, r294414, r294753

- Fix tty_drain() and, thus, TIOCDRAIN of the current tty(4) incarnation
  to actually wait until the TX FIFOs of UARTs have be drained before
  returning. This is done by bringing the equivalent of the TS_BUSY flag
  found in the previous implementation back in an ABI-preserving way.
  Reported and tested by: Patrick Powell
- Make the code consistent with itself style-wise and bring it closer
  to style(9).
- Mark unused arguments as such.
- Make the ttystates table const.

1 files changed, 33 insertions, 8 deletions

diff --git a/sys/sys/ttydevsw.h b/sys/sys/ttydevsw.h
index 748ae0b..98bebca 100644
--- a/sys/sys/ttydevsw.h
+++ b/sys/sys/ttydevsw.h
@@ -54,6 +54,7 @@ typedef int tsw_mmap_t(struct tty *tp, vm_ooffset_t offset,
     vm_paddr_t * paddr, int nprot, vm_memattr_t *memattr);
 typedef void tsw_pktnotify_t(struct tty *tp, char event);
 typedef void tsw_free_t(void *softc);
+typedef bool tsw_busy_t(struct tty *tp);
 
 struct ttydevsw {
 	unsigned int	tsw_flags;	/* Default TTY flags. */
@@ -74,21 +75,25 @@ struct ttydevsw {
 
 	tsw_free_t	*tsw_free;	/* Destructor. */
 
-	void		*tsw_spare[4];	/* For future use. */
+	tsw_busy_t	*tsw_busy;	/* Draining output. */
+
+	void		*tsw_spare[3];	/* For future use. */
 };
 
 static __inline int
 ttydevsw_open(struct tty *tp)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
-	return tp->t_devsw->tsw_open(tp);
+	return (tp->t_devsw->tsw_open(tp));
 }
 
 static __inline void
 ttydevsw_close(struct tty *tp)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
@@ -98,6 +103,7 @@ ttydevsw_close(struct tty *tp)
 static __inline void
 ttydevsw_outwakeup(struct tty *tp)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
@@ -111,6 +117,7 @@ ttydevsw_outwakeup(struct tty *tp)
 static __inline void
 ttydevsw_inwakeup(struct tty *tp)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
@@ -124,49 +131,56 @@ ttydevsw_inwakeup(struct tty *tp)
 static __inline int
 ttydevsw_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
-	return tp->t_devsw->tsw_ioctl(tp, cmd, data, td);
+	return (tp->t_devsw->tsw_ioctl(tp, cmd, data, td));
 }
 
 static __inline int
-ttydevsw_cioctl(struct tty *tp, int unit, u_long cmd, caddr_t data, struct thread *td)
+ttydevsw_cioctl(struct tty *tp, int unit, u_long cmd, caddr_t data,
+    struct thread *td)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
-	return tp->t_devsw->tsw_cioctl(tp, unit, cmd, data, td);
+	return (tp->t_devsw->tsw_cioctl(tp, unit, cmd, data, td));
 }
 
 static __inline int
 ttydevsw_param(struct tty *tp, struct termios *t)
 {
+
 	MPASS(!tty_gone(tp));
 
-	return tp->t_devsw->tsw_param(tp, t);
+	return (tp->t_devsw->tsw_param(tp, t));
 }
 
 static __inline int
 ttydevsw_modem(struct tty *tp, int sigon, int sigoff)
 {
+
 	MPASS(!tty_gone(tp));
 
-	return tp->t_devsw->tsw_modem(tp, sigon, sigoff);
+	return (tp->t_devsw->tsw_modem(tp, sigon, sigoff));
 }
 
 static __inline int
 ttydevsw_mmap(struct tty *tp, vm_ooffset_t offset, vm_paddr_t *paddr,
     int nprot, vm_memattr_t *memattr)
 {
+
 	MPASS(!tty_gone(tp));
 
-	return tp->t_devsw->tsw_mmap(tp, offset, paddr, nprot, memattr);
+	return (tp->t_devsw->tsw_mmap(tp, offset, paddr, nprot, memattr));
 }
 
 static __inline void
 ttydevsw_pktnotify(struct tty *tp, char event)
 {
+
 	tty_lock_assert(tp, MA_OWNED);
 	MPASS(!tty_gone(tp));
 
@@ -176,9 +190,20 @@ ttydevsw_pktnotify(struct tty *tp, char event)
 static __inline void
 ttydevsw_free(struct tty *tp)
 {
+
 	MPASS(tty_gone(tp));
 
 	tp->t_devsw->tsw_free(tty_softc(tp));
 }
 
+static __inline bool
+ttydevsw_busy(struct tty *tp)
+{
+
+	tty_lock_assert(tp, MA_OWNED);
+	MPASS(!tty_gone(tp));
+
+	return (tp->t_devsw->tsw_busy(tp));
+}
+
 #endif /* !_SYS_TTYDEVSW_H_ */