svn commit: r295615 - stable/10/sys/kern

[Konstantin Belousov]

Author: kib
Date: Sun Feb 14 18:57:40 2016
New Revision: 295615
URL: https://svnweb.freebsd.org/changeset/base/295615

Log:
  MFC r294598:
  In tty_dealloc(), clear the queues.
  
  Approved by:	re (marius)

Modified:
  stable/10/sys/kern/tty.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/kern/tty.c
==============================================================================
--- stable/10/sys/kern/tty.c	Sun Feb 14 18:17:58 2016	(r295614)
+++ stable/10/sys/kern/tty.c	Sun Feb 14 18:57:40 2016	(r295615)
@@ -215,7 +215,7 @@ ttydev_leave(struct tty *tp)
 
 	ttydisc_close(tp);
 
-	/* Destroy associated buffers already. */
+	/* Free i/o queues now since they might be large. */
 	ttyinq_free(&tp->t_inq);
 	tp->t_inlow = 0;
 	ttyoutq_free(&tp->t_outq);
@@ -1052,10 +1052,15 @@ tty_dealloc(void *arg)
 {
 	struct tty *tp = arg;
 
-	/* Make sure we haven't leaked buffers. */
-	MPASS(ttyinq_getsize(&tp->t_inq) == 0);
-	MPASS(ttyoutq_getsize(&tp->t_outq) == 0);
-
+	/*
+	 * ttyydev_leave() usually frees the i/o queues earlier, but it is
+	 * not always called between queue allocation and here.  The queues
+	 * may be allocated by ioctls on a pty control device without the
+	 * corresponding pty slave device ever being open, or after it is
+	 * closed.
+	 */
+	ttyinq_free(&tp->t_inq);
+	ttyoutq_free(&tp->t_outq);
 	seldrain(&tp->t_inpoll);
 	seldrain(&tp->t_outpoll);
 	knlist_destroy(&tp->t_inpoll.si_note);