--- linux-2.6.10/drivers/usb/class/cdc-acm.c.orig	Thu Feb 24 15:02:29 2005
+++ linux-2.6.10/drivers/usb/class/cdc-acm.c	Thu Feb 24 15:02:36 2005
@@ -272,7 +272,7 @@ static int acm_tty_open(struct tty_struc
 
         down(&open_sem);
 
-	if (acm->used) {
+	if (acm->used++) {
 		goto done;
         }
 
@@ -296,7 +296,6 @@ static int acm_tty_open(struct tty_struc
 	tty->low_latency = 1;
 
 done:
-	acm->used++;
 	up(&open_sem);
 	return 0;
 
@@ -305,6 +304,7 @@ full_bailout:
 bail_out_and_unlink:
 	usb_kill_urb(acm->ctrlurb);
 bail_out:
+	acm->used--;
 	up(&open_sem);
 	return -EIO;
 }