[091/119] tty_port: handle the nonblocking open of a dead port corner case

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Alan Cox <alan@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/char/tty_port.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -217,8 +217,11 @@ int tty_port_block_til_ready(struct tty_
 
 	/* 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);


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