# HG changeset patch
# User yamahata@xxxxxxxxxxxxx
# Node ID 747aaae397bf895210cf29ee7f95d03ea29888ef
# Parent  8e55c5c1147589b7a6a1875384d4317aec7ccf84
xenconsole fix. reference of tty->count in xencons_close() is racy.
It must be protected by tty_sem semaphore like con_close() in
drivers/char/vt.c. and prevent re-opening this tty.
PATCHNAME: add_tty_sem

Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>

diff -r 8e55c5c11475 -r 747aaae397bf linux-2.6-xen-sparse/drivers/xen/console/console.c
--- a/linux-2.6-xen-sparse/drivers/xen/console/console.c	Wed Jul 05 18:48:41 2006 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/console/console.c	Sat Jul 08 14:09:02 2006 +0900
@@ -536,7 +536,11 @@ static void xencons_close(struct tty_str
 	if (DUMMY_TTY(tty))
 		return;
 
+	down(&tty_sem);
 	if (tty->count == 1) {
+		/* prevent other thread re-opening this tty. */
+		set_bit(TTY_CLOSING, &tty->flags);
+		up(&tty_sem);
 		tty->closing = 1;
 		tty_wait_until_sent(tty, 0);
 		if (DRV(tty->driver)->flush_buffer != NULL)
@@ -547,7 +551,8 @@ static void xencons_close(struct tty_str
 		spin_lock_irqsave(&xencons_lock, flags);
 		xencons_tty = NULL;
 		spin_unlock_irqrestore(&xencons_lock, flags);
-	}
+	} else
+		up(&tty_sem);
 }
 
 static struct tty_operations xencons_ops = {