From 28aa9d102277d4a544ee19767f6b6e2dca476cce Mon Sep 17 00:00:00 2001
From: ed <ed@FreeBSD.org>
Date: Thu, 4 Sep 2008 16:30:53 +0000
Subject: [PATCH] Fix an awful bug inside our COMPAT_43TTY code.

When I migrated tty_compat.c to MPSAFE TTY, I just hooked it up to the
build and fixed it until it compiled and somewhat worked. It turns out
this was not the smartest thing, because the old TTY layer also had a
field called t_flags, which contained a set of sgtty flags.

This means our current COMPAT_43TTY code overwrites the TTY flags,
causing all strange problems to occur. Fix this code to use a new struct
member called t_compatflags. This commit may cause kern/127054 to be
fixed, but this still has to be tested/confirmed by the originator. It
has to be fixed anyway.

PR:		kern/127054
---
 sys/kern/tty_compat.c | 26 ++++++++++++++------------
 sys/sys/tty.h         |  1 +
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/sys/kern/tty_compat.c b/sys/kern/tty_compat.c
index 6736cfb77925..00764b89d3ee 100644
--- a/sys/kern/tty_compat.c
+++ b/sys/kern/tty_compat.c
@@ -121,7 +121,8 @@ ttsetcompat(struct tty *tp, u_long *com, caddr_t data, struct termios *term)
 			term->c_ospeed = tp->t_termios.c_ospeed;
 		term->c_cc[VERASE] = sg->sg_erase;
 		term->c_cc[VKILL] = sg->sg_kill;
-		tp->t_flags = (tp->t_flags&0xffff0000) | (sg->sg_flags&0xffff);
+		tp->t_compatflags = (tp->t_compatflags&0xffff0000) |
+		    (sg->sg_flags&0xffff);
 		ttcompatsetflags(tp, term);
 		*com = (*com == TIOCSETP) ? TIOCSETAF : TIOCSETA;
 		break;
@@ -160,14 +161,15 @@ ttsetcompat(struct tty *tp, u_long *com, caddr_t data, struct termios *term)
 	case TIOCLBIC:
 	case TIOCLSET:
 		if (*com == TIOCLSET)
-			tp->t_flags = (tp->t_flags&0xffff) | *(int *)data<<16;
+			tp->t_compatflags = (tp->t_compatflags&0xffff) |
+			    *(int *)data<<16;
 		else {
-			tp->t_flags =
-			 (ttcompatgetflags(tp)&0xffff0000)|(tp->t_flags&0xffff);
+			tp->t_compatflags = (ttcompatgetflags(tp)&0xffff0000) |
+			    (tp->t_compatflags&0xffff);
 			if (*com == TIOCLBIS)
-				tp->t_flags |= *(int *)data<<16;
+				tp->t_compatflags |= *(int *)data<<16;
 			else
-				tp->t_flags &= ~(*(int *)data<<16);
+				tp->t_compatflags &= ~(*(int *)data<<16);
 		}
 		ttcompatsetlflags(tp, term);
 		*com = TIOCSETA;
@@ -209,7 +211,7 @@ tty_ioctl_compat(struct tty *tp, u_long com, caddr_t data, struct thread *td)
 			    compatspeeds);
 		sg->sg_erase = cc[VERASE];
 		sg->sg_kill = cc[VKILL];
-		sg->sg_flags = tp->t_flags = ttcompatgetflags(tp);
+		sg->sg_flags = tp->t_compatflags = ttcompatgetflags(tp);
 		break;
 	}
 	case TIOCGETC: {
@@ -237,10 +239,10 @@ tty_ioctl_compat(struct tty *tp, u_long com, caddr_t data, struct thread *td)
 		break;
 	}
 	case TIOCLGET:
-		tp->t_flags =
+		tp->t_compatflags =
 		 (ttcompatgetflags(tp) & 0xffff0000UL)
-		   | (tp->t_flags & 0xffff);
-		*(int *)data = tp->t_flags>>16;
+		   | (tp->t_compatflags & 0xffff);
+		*(int *)data = tp->t_compatflags>>16;
 		if (ttydebug)
 			printf("CLGET: returning %x\n", *(int *)data);
 		break;
@@ -329,7 +331,7 @@ ttcompatgetflags(struct tty *tp)
 static void
 ttcompatsetflags(struct tty *tp, struct termios *t)
 {
-	int flags = tp->t_flags;
+	int flags = tp->t_compatflags;
 	tcflag_t iflag	= t->c_iflag;
 	tcflag_t oflag	= t->c_oflag;
 	tcflag_t lflag	= t->c_lflag;
@@ -406,7 +408,7 @@ ttcompatsetflags(struct tty *tp, struct termios *t)
 static void
 ttcompatsetlflags(struct tty *tp, struct termios *t)
 {
-	int flags = tp->t_flags;
+	int flags = tp->t_compatflags;
 	tcflag_t iflag	= t->c_iflag;
 	tcflag_t oflag	= t->c_oflag;
 	tcflag_t lflag	= t->c_lflag;
diff --git a/sys/sys/tty.h b/sys/sys/tty.h
index d9cf5f61bbc6..11be086bb1ed 100644
--- a/sys/sys/tty.h
+++ b/sys/sys/tty.h
@@ -103,6 +103,7 @@ struct tty {
 	struct winsize	t_winsize;	/* (t) Window size. */
 	unsigned int	t_column;	/* (t) Current cursor position. */
 	unsigned int	t_writepos;	/* (t) Where input was interrupted. */
+	int		t_compatflags;	/* (t) COMPAT_43TTY flags. */
 
 	/* Init/lock-state devices. */
 	struct termios	t_termios_init_in;	/* tty%s.init. */