linux-kernel - [PATCH 1/6] tty_port,usb-console: Fix usb serial console open/close regression

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Date:	Tue,  9 Mar 2010 00:29:06 -0600
From:	Jason Wessel <jason.wessel@...driver.com>
To:	gregkh@...e.de
Cc:	linux-usb@...r.kernel.org, Alan Stern <stern@...land.harvard.edu>,
	linux-kernel@...r.kernel.org,
	Jason Wessel <jason.wessel@...driver.com>,
	Alan Cox <alan@...ux.intel.com>,
	Oliver Neukum <oliver@...kum.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 1/6] tty_port,usb-console: Fix usb serial console open/close regression

Commit e1108a63e10d344284011cccc06328b2cd3e5da3 ("usb_serial: Use the
shutdown() operation") breaks the ability to use a usb console
starting in 2.6.33.  This was observed when using
console=ttyUSB0,115200 as a boot argument with an FTDI device.  The
error is:

ftdi_sio ttyUSB0: ftdi_submit_read_urb - failed submitting read urb, error -22

The handling of the ASYNCB_INITIALIZED changed in 2.6.32 such that in
tty_port_shutdown() it always clears the flag if it is set.  The fix
is to add a variable to the tty_port struct to indicate when the tty
port is a console.

CC: Greg Kroah-Hartman <gregkh@...e.de>
CC: Alan Cox <alan@...ux.intel.com>
CC: Alan Stern <stern@...land.harvard.edu>
CC: Oliver Neukum <oliver@...kum.org>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: linux-usb@...r.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
---
 drivers/char/tty_port.c      |    2 +-
 drivers/usb/serial/console.c |    1 +
 include/linux/tty.h          |    1 +
 3 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index be492dd..a3bd1d0 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -119,7 +119,7 @@ EXPORT_SYMBOL(tty_port_tty_set);
 static void tty_port_shutdown(struct tty_port *port)
 {
 	mutex_lock(&port->mutex);
-	if (port->ops->shutdown &&
+	if (port->ops->shutdown && !port->console &&
 		test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
 			port->ops->shutdown(port);
 	mutex_unlock(&port->mutex);
diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c
index b22ac32..f347da2 100644
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -181,6 +181,7 @@ static int usb_console_setup(struct console *co, char *options)
 	/* The console is special in terms of closing the device so
 	 * indicate this port is now acting as a system console. */
 	port->console = 1;
+	port->port.console = 1;
 
 	mutex_unlock(&serial->disc_mutex);
 	return retval;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index d96e588..a42d7a6 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -223,6 +223,7 @@ struct tty_port {
 	wait_queue_head_t	close_wait;	/* Close waiters */
 	wait_queue_head_t	delta_msr_wait;	/* Modem status change */
 	unsigned long		flags;		/* TTY flags ASY_*/
+	unsigned char		console:1;	/* port is a console */
 	struct mutex		mutex;		/* Locking */
 	struct mutex		buf_mutex;	/* Buffer alloc lock */
 	unsigned char		*xmit_buf;	/* Optional buffer */
-- 
1.6.3.1.9.g95405b

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