[PATCH 1/3] tty_port: handle the nonblocking open of a dead port corner case

[Greg Kroah-Hartman]

From: Alan Cox <alan@xxxxxxxxxxxxxxx>

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>
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 drivers/char/tty_port.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 2e8552d..c63f3d3 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -219,8 +219,11 @@ 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);
-- 
1.6.4.2

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