Use a new message buffer `consmsgbuf' to forward messages to a

TIOCCONS console (e.g. xconsole) via a timeout routine instead of
calling into the tty code directly from printf(). This fixes a
number of cases where calling printf() at the wrong time (such as
with locks held) would cause a panic if xconsole is running.

The TIOCCONS message buffer is 8k in size by default, but this can
be changed with the kern.consmsgbuf_size sysctl. By default, messages
are checked for 5 times per second. The timer runs and the buffer
memory remains allocated only at times when a TIOCCONS console is
active.

Discussed on:	freebsd-arch

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/kern/tty.c b/sys/kern/tty.c
index 1c8aa6bcce5b..4bebd65cf969 100644
--- a/sys/kern/tty.c
+++ b/sys/kern/tty.c
@@ -261,7 +261,7 @@ ttyclose(struct tty *tp)
 	funsetown(&tp->t_sigio);
 	s = spltty();
 	if (constty == tp)
-		constty = NULL;
+		constty_clear();
 
 	ttyflush(tp, FREAD | FWRITE);
 	clist_free_cblocks(&tp->t_canq);
@@ -871,9 +871,9 @@ ttioctl(struct tty *tp, u_long cmd, void *data, int flag)
 			if (error)
 				return (error);
 
-			constty = tp;
+			constty_set(tp);
 		} else if (tp == constty)
-			constty = NULL;
+			constty_clear();
 		break;
 	case TIOCDRAIN:			/* wait till output drained */
 		error = ttywait(tp);