From: Alan Cox <alan@linux.intel.com>
Date: Wed, 18 Nov 2009 14:12:58 +0000 (+0000)
Subject: tty_port: handle the nonblocking open of a dead port corner case
X-Git-Tag: v2.6.31.7~29
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d9abf6e4f67279f0ea926e6beef7baa9661dce75;p=karo-tx-linux.git

tty_port: handle the nonblocking open of a dead port corner case

commit 8627b96dd80dca440d91fbb1ec733be25912d0dd upstream.

Some drivers allow O_NDELAY of a dead port (eg for setserial to work). In that
situation we must not try to raise the carrier.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 6db51f37e2c8..c0ff7eeafbb2 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -217,8 +217,11 @@ int tty_port_block_til_ready(struct tty_port *port,
 
 	/* if non-blocking mode is set we can pass directly to open unless
 	   the port has just hung up or is in another error state */
-	if ((filp->f_flags & O_NONBLOCK) ||
-			(tty->flags & (1 << TTY_IO_ERROR))) {
+	if (tty->flags & (1 << TTY_IO_ERROR)) {
+		port->flags |= ASYNC_NORMAL_ACTIVE;
+		return 0;
+	}
+	if (filp->f_flags & O_NONBLOCK) {
 		/* Indicate we are open */
 		if (tty->termios->c_cflag & CBAUD)
 			tty_port_raise_dtr_rts(port);