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 6db51f37e2c8e64f14b253f770f002a913d32be8..c0ff7eeafbb21930c68c6d28b7664ca583589624 100644 (file)
--- 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);