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From: Greg Kroah-Hartman on 5 Aug 2010 18:40
From: Alan Cox <alan(a)linux.intel.com>

Make it robust against hang up events. In most cases we can do this simply
by passing the right things in the first place.

Signed-off-by: Alan Cox <alan(a)linux.intel.com>
Cc: Arnd Bergmann <arnd(a)arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>
---
drivers/serial/serial_core.c | 109 +++++++++++++++++++++++-------------------
1 files changed, 60 insertions(+), 49 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 7f28307..12ee7e0 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -58,7 +58,7 @@ static struct lock_class_key port_lock_key;
#define uart_console(port) (0)
#endif

-static void uart_change_speed(struct uart_state *state,
+static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
static void uart_change_pm(struct uart_state *state, int pm_state);
@@ -137,7 +137,7 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
* Startup the port. This will be called once per open. All calls
* will be serialised by the per-port mutex.
*/
-static int uart_startup(struct uart_state *state, int init_hw)
+static int uart_startup(struct tty_struct *tty, struct uart_state *state, int init_hw)
{
struct uart_port *uport = state->uart_port;
struct tty_port *port = &state->port;
@@ -152,7 +152,7 @@ static int uart_startup(struct uart_state *state, int init_hw)
* once we have successfully opened the port. Also set
* up the tty->alt_speed kludge
*/
- set_bit(TTY_IO_ERROR, &port->tty->flags);
+ set_bit(TTY_IO_ERROR, &tty->flags);

if (uport->type == PORT_UNKNOWN)
return 0;
@@ -177,26 +177,26 @@ static int uart_startup(struct uart_state *state, int init_hw)
/*
* Initialise the hardware port settings.
*/
- uart_change_speed(state, NULL);
+ uart_change_speed(tty, state, NULL);

/*
* Setup the RTS and DTR signals once the
* port is open and ready to respond.
*/
- if (port->tty->termios->c_cflag & CBAUD)
+ if (tty->termios->c_cflag & CBAUD)
uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
}

if (port->flags & ASYNC_CTS_FLOW) {
spin_lock_irq(&uport->lock);
if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))
- port->tty->hw_stopped = 1;
+ tty->hw_stopped = 1;
spin_unlock_irq(&uport->lock);
}

set_bit(ASYNCB_INITIALIZED, &port->flags);

- clear_bit(TTY_IO_ERROR, &port->tty->flags);
+ clear_bit(TTY_IO_ERROR, &tty->flags);
}

if (retval && capable(CAP_SYS_ADMIN))
@@ -210,11 +210,10 @@ static int uart_startup(struct uart_state *state, int init_hw)
* DTR is dropped if the hangup on close termio flag is on. Calls to
* uart_shutdown are serialised by the per-port semaphore.
*/
-static void uart_shutdown(struct uart_state *state)
+static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
{
struct uart_port *uport = state->uart_port;
struct tty_port *port = &state->port;
- struct tty_struct *tty = port->tty;

/*
* Set the TTY IO error marker
@@ -430,11 +429,10 @@ uart_get_divisor(struct uart_port *port, unsigned int baud)
EXPORT_SYMBOL(uart_get_divisor);

/* FIXME: Consistent locking policy */
-static void
-uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
+static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
+ struct ktermios *old_termios)
{
struct tty_port *port = &state->port;
- struct tty_struct *tty = port->tty;
struct uart_port *uport = state->uart_port;
struct ktermios *termios;

@@ -463,8 +461,8 @@ uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
uport->ops->set_termios(uport, termios, old_termios);
}

-static inline int
-__uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
+static inline int __uart_put_char(struct uart_port *port,
+ struct circ_buf *circ, unsigned char c)
{
unsigned long flags;
int ret = 0;
@@ -494,8 +492,8 @@ static void uart_flush_chars(struct tty_struct *tty)
uart_start(tty);
}

-static int
-uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
+static int uart_write(struct tty_struct *tty,
+ const unsigned char *buf, int count)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port;
@@ -675,7 +673,7 @@ static int uart_get_info(struct uart_state *state,
return 0;
}

-static int uart_set_info(struct uart_state *state,
+static int uart_set_info(struct tty_struct *tty, struct uart_state *state,
struct serial_struct __user *newinfo)
{
struct serial_struct new_serial;
@@ -770,7 +768,7 @@ static int uart_set_info(struct uart_state *state,
* We need to shutdown the serial port at the old
* port/type/irq combination.
*/
- uart_shutdown(state);
+ uart_shutdown(tty, state);
}

if (change_port) {
@@ -869,25 +867,27 @@ static int uart_set_info(struct uart_state *state,
"is deprecated.\n", current->comm,
tty_name(port->tty, buf));
}
- uart_change_speed(state, NULL);
+ uart_change_speed(tty, state, NULL);
}
} else
- retval = uart_startup(state, 1);
+ retval = uart_startup(tty, state, 1);
exit:
mutex_unlock(&port->mutex);
return retval;
}

-
-/*
- * uart_get_lsr_info - get line status register info.
- * Note: uart_ioctl protects us against hangups.
+/**
+ * uart_get_lsr_info - get line status register info
+ * @tty: tty associated with the UART
+ * @state: UART being queried
+ * @value: returned modem value
+ *
+ * Note: uart_ioctl protects us against hangups.
*/
-static int uart_get_lsr_info(struct uart_state *state,
- unsigned int __user *value)
+static int uart_get_lsr_info(struct tty_struct *tty,
+ struct uart_state *state, unsigned int __user *value)
{
struct uart_port *uport = state->uart_port;
- struct tty_port *port = &state->port;
unsigned int result;

result = uport->ops->tx_empty(uport);
@@ -900,7 +900,7 @@ static int uart_get_lsr_info(struct uart_state *state,
*/
if (uport->x_char ||
((uart_circ_chars_pending(&state->xmit) > 0) &&
- !port->tty->stopped && !port->tty->hw_stopped))
+ !tty->stopped && !tty->hw_stopped))
result &= ~TIOCSER_TEMT;

return put_user(result, value);
@@ -961,7 +961,7 @@ static int uart_break_ctl(struct tty_struct *tty, int break_state)
return 0;
}

-static int uart_do_autoconfig(struct uart_state *state)
+static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
{
struct uart_port *uport = state->uart_port;
struct tty_port *port = &state->port;
@@ -980,7 +980,7 @@ static int uart_do_autoconfig(struct uart_state *state)

ret = -EBUSY;
if (tty_port_users(port) == 1) {
- uart_shutdown(state);
+ uart_shutdown(tty, state);

/*
* If we already have a port type configured,
@@ -999,7 +999,7 @@ static int uart_do_autoconfig(struct uart_state *state)
*/
uport->ops->config_port(uport, flags);

- ret = uart_startup(state, 1);
+ ret = uart_startup(tty, state, 1);
}
mutex_unlock(&port->mutex);
return ret;
@@ -1122,11 +1122,11 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
break;

case TIOCSSERIAL:
- ret = uart_set_info(state, uarg);
+ ret = uart_set_info(tty, state, uarg);
break;

case TIOCSERCONFIG:
- ret = uart_do_autoconfig(state);
+ ret = uart_do_autoconfig(tty, state);
break;

case TIOCSERGWILD: /* obsolete */
@@ -1172,7 +1172,7 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
*/
switch (cmd) {
case TIOCSERGETLSR: /* Get line status register */
- ret = uart_get_lsr_info(state, uarg);
+ ret = uart_get_lsr_info(tty, state, uarg);
break;

default: {
@@ -1219,7 +1219,7 @@ static void uart_set_termios(struct tty_struct *tty,
return;
}

- uart_change_speed(state, old_termios);
+ uart_change_speed(tty, state, old_termios);

/* Handle transition to B0 status */
if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
@@ -1335,7 +1335,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
uart_wait_until_sent(tty, uport->timeout);
}

- uart_shutdown(state);
+ uart_shutdown(tty, state);
uart_flush_buffer(tty);

tty_ldisc_flush(tty);
@@ -1436,7 +1436,7 @@ static void uart_hangup(struct tty_struct *tty)
mutex_lock(&port->mutex);
if (port->flags & ASYNC_NORMAL_ACTIVE) {
uart_flush_buffer(tty);
- uart_shutdown(state);
+ uart_shutdown(tty, state);
port->count = 0;
clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
tty_port_tty_set(port, NULL);
@@ -1446,15 +1446,19 @@ static void uart_hangup(struct tty_struct *tty)
mutex_unlock(&port->mutex);
}

-/*
- * Copy across the serial console cflag setting into the termios settings
- * for the initial open of the port. This allows continuity between the
- * kernel settings, and the settings init adopts when it opens the port
- * for the first time.
+/**
+ * uart_update_termios - update the terminal hw settings
+ * @tty: tty associated with UART
+ * @state: UART to update
+ *
+ * Copy across the serial console cflag setting into the termios settings
+ * for the initial open of the port. This allows continuity between the
+ * kernel settings, and the settings init adopts when it opens the port
+ * for the first time.
*/
-static void uart_update_termios(struct uart_state *state)
+static void uart_update_termios(struct tty_struct *tty,
+ struct uart_state *state)
{
- struct tty_struct *tty = state->port.tty;
struct uart_port *port = state->uart_port;

if (uart_console(port) && port->cons->cflag) {
@@ -1471,7 +1475,7 @@ static void uart_update_termios(struct uart_state *state)
/*
* Make termios settings take effect.
*/
- uart_change_speed(state, NULL);
+ uart_change_speed(tty, state, NULL);

/*
* And finally enable the RTS and DTR signals.
@@ -1668,7 +1672,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
/*
* Start up the serial port.
*/
- retval = uart_startup(state, 0);
+ retval = uart_startup(tty, state, 0);

/*
* If we succeeded, wait until the port is ready.
@@ -1683,7 +1687,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
if (retval == 0 && !(port->flags & ASYNC_NORMAL_ACTIVE)) {
set_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);

- uart_update_termios(state);
+ uart_update_termios(tty, state);
}

fail:
@@ -2010,9 +2014,13 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
struct tty_port *port = &state->port;
struct device *tty_dev;
struct uart_match match = {uport, drv};
+ struct tty_struct *tty;

mutex_lock(&port->mutex);

+ /* Must be inside the mutex lock until we convert to tty_port */
+ tty = port->tty;
+
tty_dev = device_find_child(uport->dev, &match, serial_match_port);
if (device_may_wakeup(tty_dev)) {
enable_irq_wake(uport->irq);
@@ -2105,9 +2113,12 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
ops->set_mctrl(uport, 0);
spin_unlock_irq(&uport->lock);
if (console_suspend_enabled || !uart_console(uport)) {
+ /* Protected by port mutex for now */
+ struct tty_struct *tty = port->tty;
ret = ops->startup(uport);
if (ret == 0) {
- uart_change_speed(state, NULL);
+ if (tty)
+ uart_change_speed(tty, state, NULL);
spin_lock_irq(&uport->lock);
ops->set_mctrl(uport, uport->mctrl);
ops->start_tx(uport);
@@ -2119,7 +2130,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
* Clear the "initialized" flag so we won't try
* to call the low level drivers shutdown method.
*/
- uart_shutdown(state);
+ uart_shutdown(tty, state);
}
}

--
1.7.2

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Next: [PATCH 51/67] serial: crisv10: formatting of pointers in printk()