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Subject[PATCH 30/67] serial: Change the wait for carrier locking
Date
From: Alan Cox <alan@linux.intel.com>

We want to push the lock/unlock into the helper functions so that we
can prepare to move to using the tty_port helper. The expansion initially
comes out a bit ugly but its worth the temporary expansion IMHO just so
we can produce a nice testable series of changes.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/serial/serial_core.c | 44 +++++++++++++++++++++++++++++++++--------
1 files changed, 35 insertions(+), 9 deletions(-)
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 570dca2..424b1c7 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1272,6 +1272,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
struct uart_state *state = tty->driver_data;
struct tty_port *port;
struct uart_port *uport;
+ unsigned long flags;

BUG_ON(!kernel_locked());

@@ -1284,9 +1285,12 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
pr_debug("uart_close(%d) called\n", uport->line);

mutex_lock(&port->mutex);
+ spin_lock_irqsave(&port->lock, flags);

- if (tty_hung_up_p(filp))
+ if (tty_hung_up_p(filp)) {
+ spin_unlock_irqrestore(&port->lock, flags);
goto done;
+ }

if ((tty->count == 1) && (port->count != 1)) {
/*
@@ -1305,8 +1309,10 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
tty->name, port->count);
port->count = 0;
}
- if (port->count)
+ if (port->count) {
+ spin_unlock_irqrestore(&port->lock, flags);
goto done;
+ }

/*
* Now we wait for the transmit buffer to clear; and we notify
@@ -1314,6 +1320,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
* setting tty->closing.
*/
tty->closing = 1;
+ spin_unlock_irqrestore(&port->lock, flags);

if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
tty_wait_until_sent(tty, msecs_to_jiffies(port->closing_wait));
@@ -1340,20 +1347,26 @@ static void uart_close(struct tty_struct *tty, struct file *filp)

tty_ldisc_flush(tty);

- tty->closing = 0;
tty_port_tty_set(port, NULL);
+ spin_lock_irqsave(&port->lock, flags);
+ tty->closing = 0;

if (port->blocked_open) {
+ spin_unlock_irqrestore(&port->lock, flags);
if (port->close_delay)
msleep_interruptible(port->close_delay);
+ spin_lock_irqsave(&port->lock, flags);
} else if (!uart_console(uport)) {
+ spin_unlock_irqrestore(&port->lock, flags);
uart_change_pm(state, 3);
+ spin_lock_irqsave(&port->lock, flags);
}

/*
* Wake up anyone trying to open this port.
*/
clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
+ spin_unlock_irqrestore(&port->lock, flags);
wake_up_interruptible(&port->open_wait);

done:
@@ -1429,6 +1442,7 @@ static void uart_hangup(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct tty_port *port = &state->port;
+ unsigned long flags;

BUG_ON(!kernel_locked());
pr_debug("uart_hangup(%d)\n", state->uart_port->line);
@@ -1437,8 +1451,10 @@ static void uart_hangup(struct tty_struct *tty)
if (port->flags & ASYNC_NORMAL_ACTIVE) {
uart_flush_buffer(tty);
uart_shutdown(tty, state);
+ spin_lock_irqsave(&port->lock, flags);
port->count = 0;
clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
+ spin_unlock_irqrestore(&port->lock, flags);
tty_port_tty_set(port, NULL);
wake_up_interruptible(&port->open_wait);
wake_up_interruptible(&port->delta_msr_wait);
@@ -1496,9 +1512,13 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
struct uart_port *uport = state->uart_port;
struct tty_port *port = &state->port;
unsigned int mctrl;
+ unsigned long flags;

+ spin_lock_irqsave(&port->lock, flags);
+ if (!tty_hung_up_p(filp))
+ port->count--;
port->blocked_open++;
- port->count--;
+ spin_unlock_irqrestore(&port->lock, flags);

add_wait_queue(&port->open_wait, &wait);
while (1) {
@@ -1535,23 +1555,26 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
* not set RTS here - we want to make sure we catch
* the data from the modem.
*/
- if (port->tty->termios->c_cflag & CBAUD)
+ if (port->tty->termios->c_cflag & CBAUD) {
+ mutex_lock(&port->mutex);
uart_set_mctrl(uport, TIOCM_DTR);
+ mutex_unlock(&port->mutex);
+ }

/*
* and wait for the carrier to indicate that the
* modem is ready for us.
*/
+ mutex_lock(&port->mutex);
spin_lock_irq(&uport->lock);
uport->ops->enable_ms(uport);
mctrl = uport->ops->get_mctrl(uport);
spin_unlock_irq(&uport->lock);
+ mutex_unlock(&port->mutex);
if (mctrl & TIOCM_CAR)
break;

- mutex_unlock(&port->mutex);
schedule();
- mutex_lock(&port->mutex);

if (signal_pending(current))
break;
@@ -1559,8 +1582,11 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
set_current_state(TASK_RUNNING);
remove_wait_queue(&port->open_wait, &wait);

- port->count++;
+ spin_lock_irqsave(&port->lock, flags);
+ if (!tty_hung_up_p(filp))
+ port->count++;
port->blocked_open--;
+ spin_unlock_irqrestore(&port->lock, flags);

if (signal_pending(current))
return -ERESTARTSYS;
@@ -1677,9 +1703,9 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
/*
* If we succeeded, wait until the port is ready.
*/
+ mutex_unlock(&port->mutex);
if (retval == 0)
retval = uart_block_til_ready(filp, state);
- mutex_unlock(&port->mutex);

/*
* If this is the first open to succeed, adjust things to suit.
--
1.7.2


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