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tty_port: If we are opened non blocking we still need to raise the carrier 

Original discussion:
http://thread.gmane.org/gmane.linux.usb.general/23217/focus=23248
or
http://marc.info/?l=linux-usb&m=125553790714133&w=2

The tty_port code inherited a bug common to various drivers it was based
upon. If the tty is opened O_NONBLOCK we do not wait for the carrier to be
raised but we must still raise our modem lines if appropriate.

(There is a second question here about whether we should do so if CLOCAL is
 set but that can wait)

Signed-off-by: Alan Cox <alan@linux.intel.com>
Reported-by: Karl Hiramoto <karl@hiramoto.org>
Tested-by:  Karl Hiramoto <karl@hiramoto.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox 2009-10-28 21:12:32 +01:00 committed by Greg Kroah-Hartman
parent ac50e95078
commit 4175f3e31c
1 changed files with 3 additions and 0 deletions
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3
drivers/char/tty_port.c
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@ -221,6 +221,9 @@ int tty_port_block_til_ready(struct tty_port *port,
the port has just hung up or is in another error state */
if ((filp->f_flags & O_NONBLOCK) ||
(tty->flags & (1 << TTY_IO_ERROR))) {
/* Indicate we are open */
if (tty->termios->c_cflag & CBAUD)
tty_port_raise_dtr_rts(port);
port->flags |= ASYNC_NORMAL_ACTIVE;
return 0;
}