TTY: pdc_cons, fix regression in close

The test in pdc_console_tty_close '!tty->count' was always wrong
because tty->count is decremented after tty->ops->close is called and
thus can never be zero. Hence the 'then' branch was never executed and
the timer never deleted.

This did not matter until commit 5dd5bc4 ("TTY: pdc_cons, use
tty_port").  There we needed to set TTY in tty_port to NULL, but this
never happened due to the bug above.

So change the test to really trigger at the last close by changing the
condition to 'tty->count == 1'.

Well, the driver should not touch tty->count at all.  It should use
tty_port->count and count open count there itself.

Signed-off-by: Jiri Slaby <[email protected]>
Reported-and-tested-by: Mikulas Patocka <[email protected]>
Cc: Kyle McMartin <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Jiri Slaby

arch/parisc/kernel/pdc_cons.c

@@ -104,7 +104,7 @@ static int pdc_console_tty_open(struct tty_struct *tty, struct file *filp)
 
 static void pdc_console_tty_close(struct tty_struct *tty, struct file *filp)
 {
-	if (!tty->count) {
+	if (tty->count == 1) {
 		del_timer_sync(&pdc_console_timer);
 		tty_port_tty_set(&tty_port, NULL);
 	}