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Date: Mon, 08 Mar 2010 12:50:30 -0600
From: Jason Wessel <jason.wessel@...driver.com>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
CC: Alan Stern <stern@...land.harvard.edu>,
Greg Kroah-Hartman <gregkh@...e.de>,
Alan Cox <alan@...ux.intel.com>,
Oliver Neukum <oliver@...kum.org>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb-serial: Fix usb serial console open/close regression
Alan Cox wrote:
>> This is a little unfortunate. It would be better to prevent
>> tty_port_shutdown() from clearing ASYNCB_INITIALIZED in the first
>> place. The problem is that the tty core doesn't know when the port is
>> being used as a console. There ought to be a way to tell it.
>
> Agreed - there should probably be a port.console flag to push it up into
> the tty_port logic as well.
>
Alan, are you thinking about something like the patch one listed below?
That led me to wonder if we additionally want to remove the ->console
semi-private variable from the usb-serial port struct. I tested that
and included a patch here as well as an RFC.
If we come to agreement I'll send new patches with appropriate
patch headers.
Thanks,
Jason.
----- PATCH ONE STARTS HERE-----
---
drivers/char/tty_port.c | 2 +-
drivers/usb/serial/console.c | 1 +
include/linux/serial.h | 1 +
3 files changed, 3 insertions(+), 1 deletion(-)
--- 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 && !test_bit(ASYNCB_CONSOLE, &port->flags) &&
test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
port->ops->shutdown(port);
mutex_unlock(&port->mutex);
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -132,6 +132,7 @@ struct serial_uart_config {
#define ASYNCB_CONS_FLOW 23 /* flow control for console */
#define ASYNCB_BOOT_ONLYMCA 22 /* Probe only if MCA bus */
#define ASYNCB_FIRST_KERNEL 22
+#define ASYNCB_CONSOLE 21 /* Serial port is console */
#define ASYNC_HUP_NOTIFY (1U << ASYNCB_HUP_NOTIFY)
#define ASYNC_SUSPENDED (1U << ASYNCB_SUSPENDED)
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -181,6 +181,7 @@ static int usb_console_setup(struct cons
/* The console is special in terms of closing the device so
* indicate this port is now acting as a system console. */
port->console = 1;
+ set_bit(ASYNCB_CONSOLE, &port->port.flags);
mutex_unlock(&serial->disc_mutex);
return retval;
----- PART TWO STARTS HERE -----
Remove the console variable from the usb serial private data.
---
drivers/usb/serial/console.c | 5 ++---
drivers/usb/serial/ftdi_sio.c | 3 ++-
drivers/usb/serial/generic.c | 4 ++--
drivers/usb/serial/pl2303.c | 3 ++-
drivers/usb/serial/usb-serial.c | 4 ++--
include/linux/usb/serial.h | 2 --
6 files changed, 10 insertions(+), 11 deletions(-)
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -66,7 +66,6 @@ enum port_dev_state {
* @work: work queue entry for the line discipline waking up.
* @throttled: nonzero if the read urb is inactive to throttle the device
* @throttle_req: nonzero if the tty wants to throttle us
- * @console: attached usb serial console
* @dev: pointer to the serial device
*
* This structure is used by the usb-serial core and drivers for the specific
@@ -106,7 +105,6 @@ struct usb_serial_port {
struct work_struct work;
char throttled;
char throttle_req;
- char console;
unsigned long sysrq; /* sysrq timeout */
struct device dev;
enum port_dev_state dev_state;
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -180,7 +180,6 @@ static int usb_console_setup(struct cons
--port->port.count;
/* The console is special in terms of closing the device so
* indicate this port is now acting as a system console. */
- port->console = 1;
set_bit(ASYNCB_CONSOLE, &port->port.flags);
mutex_unlock(&serial->disc_mutex);
@@ -217,7 +216,7 @@ static void usb_console_write(struct con
dbg("%s - port %d, %d byte(s)", __func__, port->number, count);
- if (!port->console) {
+ if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
dbg("%s - port not opened", __func__);
return;
}
@@ -313,7 +312,7 @@ void usb_serial_console_exit(void)
{
if (usbcons_info.port) {
unregister_console(&usbcons);
- usbcons_info.port->console = 0;
+ clear_bit(ASYNCB_CONSOLE, &usbcons_info.port->port.flags);
usbcons_info.port = NULL;
}
}
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2073,7 +2073,8 @@ static int ftdi_process_packet(struct tt
return 0; /* status only */
ch = packet + 2;
- if (!(port->console && port->sysrq) && flag == TTY_NORMAL)
+ if (!(test_bit(ASYNCB_INITIALIZED, &port->port.flags) &&
+ port->sysrq) && flag == TTY_NORMAL)
tty_insert_flip_string(tty, ch, len);
else {
for (i = 0; i < len; i++, ch++) {
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -437,7 +437,7 @@ static void flush_and_resubmit_read_urb(
/* The per character mucking around with sysrq path it too slow for
stuff like 3G modems, so shortcircuit it in the 99.9999999% of cases
where the USB serial is not a console anyway */
- if (!port->console || !port->sysrq)
+ if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags) || !port->sysrq)
tty_insert_flip_string(tty, ch, urb->actual_length);
else {
/* Push data to tty */
@@ -556,7 +556,7 @@ void usb_serial_generic_unthrottle(struc
int usb_serial_handle_sysrq_char(struct tty_struct *tty,
struct usb_serial_port *port, unsigned int ch)
{
- if (port->sysrq && port->console) {
+ if (port->sysrq && test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
if (ch && time_before(jiffies, port->sysrq)) {
handle_sysrq(ch, tty);
port->sysrq = 0;
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -1056,7 +1056,8 @@ static void pl2303_push_data(struct tty_
if (line_status & UART_OVERRUN_ERROR)
tty_insert_flip_char(tty, 0, TTY_OVERRUN);
- if (tty_flag == TTY_NORMAL && !(port->console && port->sysrq))
+ if (tty_flag == TTY_NORMAL &&
+ !(test_bit(ASYNCB_INITIALIZED, &port->port.flags) && port->sysrq))
tty_insert_flip_string(tty, data, urb->actual_length);
else {
int i;
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -289,7 +289,7 @@ static void serial_down(struct tty_port
* The console is magical. Do not hang up the console hardware
* or there will be tears.
*/
- if (port->console)
+ if (test_bit(ASYNCB_INITIALIZED, &port->port.flags))
return;
if (drv->close)
drv->close(port);
@@ -328,7 +328,7 @@ static void serial_cleanup(struct tty_st
/* The console is magical. Do not hang up the console hardware
* or there will be tears.
*/
- if (port->console)
+ if (test_bit(ASYNCB_INITIALIZED, &port->port.flags))
return;
dbg("%s - port %d", __func__, port->number);
--
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