[PATCH 65/75] tty: We want the port object to be persistent

Alan Cox
2009-01-02T13:49:11Z

From: Alan Cox <alan@redhat.com>

Move the tty_port and uart_info bits around a little. By embedding the uart_info
into the uart_port we get rid of lots of corner case testing and also get the
ability to go port<->state<->info which is a bit more elegant than the current
data structures.

Downsides - we allocate a tiny bit more memory for unused ports, upside we've
removed as much code as it saved for most users..

Signed-off-by: Alan Cox <alan@redhat.com>
---

drivers/serial/jsm/jsm_tty.c | 2 -
drivers/serial/serial_core.c | 144 ++++++++++++++++++------------------------
include/linux/serial_core.h | 62 ++++++++++--------
3 files changed, 96 insertions(+), 112 deletions(-)

diff --git a/drivers/serial/jsm/jsm_tty.c b/drivers/serial/jsm/jsm_tty.c
index a697914..3547558 100644
--- a/drivers/serial/jsm/jsm_tty.c
+++ b/drivers/serial/jsm/jsm_tty.c
@@ -272,7 +272,7 @@ static void jsm_tty_close(struct uart_port *port)
jsm_printk(CLOSE, INFO, &channel->ch_bd->pci_dev, "start\n");

bd = channel->ch_bd;
- ts = channel->uart_port.info->port.tty->termios;
+ ts = port->info->port.tty->termios;

channel->ch_flags &= ~(CH_STOPI);

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 874786a..daeba1c 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -50,7 +50,7 @@ static struct lock_class_key port_lock_key;

#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)

-#define uart_users(state) ((state)->count + ((state)->info ? (state)->info->port.blocked_open : 0))
+#define uart_users(state) ((state)->count + (state)->info.port.blocked_open)

#ifdef CONFIG_SERIAL_CORE_CONSOLE
#define uart_console(port) ((port)->cons && (port)->cons->index == (port)->line)
@@ -94,7 +94,7 @@ static void __uart_start(struct tty_struct *tty)
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;

- if (!uart_circ_empty(&state->info->xmit) && state->info->xmit.buf &&
+ if (!uart_circ_empty(&state->info.xmit) && state->info.xmit.buf &&
!tty->stopped && !tty->hw_stopped)
port->ops->start_tx(port);
}
@@ -113,7 +113,7 @@ static void uart_start(struct tty_struct *tty)
static void uart_tasklet_action(unsigned long data)
{
struct uart_state *state = (struct uart_state *)data;
- tty_wakeup(state->info->port.tty);
+ tty_wakeup(state->info.port.tty);
}

static inline void
@@ -139,7 +139,7 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
*/
static int uart_startup(struct uart_state *state, int init_hw)
{
- struct uart_info *info = state->info;
+ struct uart_info *info = &state->info;
struct uart_port *port = state->port;
unsigned long page;
int retval = 0;
@@ -212,14 +212,15 @@ static int uart_startup(struct uart_state *state, int init_hw)
*/
static void uart_shutdown(struct uart_state *state)
{
- struct uart_info *info = state->info;
+ struct uart_info *info = &state->info;
struct uart_port *port = state->port;
+ struct tty_struct *tty = info->port.tty;

/*
* Set the TTY IO error marker
*/
- if (info->port.tty)
- set_bit(TTY_IO_ERROR, &info->port.tty->flags);
+ if (tty)
+ set_bit(TTY_IO_ERROR, &tty->flags);

if (info->flags & UIF_INITIALIZED) {
info->flags &= ~UIF_INITIALIZED;
@@ -227,7 +228,7 @@ static void uart_shutdown(struct uart_state *state)
/*
* Turn off DTR and RTS early.
*/
- if (!info->port.tty || (info->port.tty->termios->c_cflag & HUPCL))
+ if (!tty || (tty->termios->c_cflag & HUPCL))
uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);

/*
@@ -427,7 +428,7 @@ EXPORT_SYMBOL(uart_get_divisor);
static void
uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
{
- struct tty_struct *tty = state->info->port.tty;
+ struct tty_struct *tty = state->info.port.tty;
struct uart_port *port = state->port;
struct ktermios *termios;

@@ -444,14 +445,14 @@ uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
* Set flags based on termios cflag
*/
if (termios->c_cflag & CRTSCTS)
- state->info->flags |= UIF_CTS_FLOW;
+ state->info.flags |= UIF_CTS_FLOW;
else
- state->info->flags &= ~UIF_CTS_FLOW;
+ state->info.flags &= ~UIF_CTS_FLOW;

if (termios->c_cflag & CLOCAL)
- state->info->flags &= ~UIF_CHECK_CD;
+ state->info.flags &= ~UIF_CHECK_CD;
else
- state->info->flags |= UIF_CHECK_CD;
+ state->info.flags |= UIF_CHECK_CD;

port->ops->set_termios(port, termios, old_termios);
}
@@ -479,7 +480,7 @@ static int uart_put_char(struct tty_struct *tty, unsigned char ch)
{
struct uart_state *state = tty->driver_data;

- return __uart_put_char(state->port, &state->info->xmit, ch);
+ return __uart_put_char(state->port, &state->info.xmit, ch);
}

static void uart_flush_chars(struct tty_struct *tty)
@@ -500,13 +501,13 @@ uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
* This means you called this function _after_ the port was
* closed. No cookie for you.
*/
- if (!state || !state->info) {
+ if (!state) {
WARN_ON(1);
return -EL3HLT;
}

port = state->port;
- circ = &state->info->xmit;
+ circ = &state->info.xmit;

if (!circ->buf)
return 0;
@@ -537,7 +538,7 @@ static int uart_write_room(struct tty_struct *tty)
int ret;

spin_lock_irqsave(&state->port->lock, flags);
- ret = uart_circ_chars_free(&state->info->xmit);
+ ret = uart_circ_chars_free(&state->info.xmit);
spin_unlock_irqrestore(&state->port->lock, flags);
return ret;
}
@@ -549,7 +550,7 @@ static int uart_chars_in_buffer(struct tty_struct *tty)
int ret;

spin_lock_irqsave(&state->port->lock, flags);
- ret = uart_circ_chars_pending(&state->info->xmit);
+ ret = uart_circ_chars_pending(&state->info.xmit);
spin_unlock_irqrestore(&state->port->lock, flags);
return ret;
}
@@ -564,7 +565,7 @@ static void uart_flush_buffer(struct tty_struct *tty)
* This means you called this function _after_ the port was
* closed. No cookie for you.
*/
- if (!state || !state->info) {
+ if (!state) {
WARN_ON(1);
return;
}
@@ -573,7 +574,7 @@ static void uart_flush_buffer(struct tty_struct *tty)
pr_debug("uart_flush_buffer(%d) called\n", tty->index);

spin_lock_irqsave(&port->lock, flags);
- uart_circ_clear(&state->info->xmit);
+ uart_circ_clear(&state->info.xmit);
if (port->ops->flush_buffer)
port->ops->flush_buffer(port);
spin_unlock_irqrestore(&port->lock, flags);
@@ -837,15 +838,15 @@ static int uart_set_info(struct uart_state *state,
state->closing_wait = closing_wait;
if (new_serial.xmit_fifo_size)
port->fifosize = new_serial.xmit_fifo_size;
- if (state->info->port.tty)
- state->info->port.tty->low_latency =
+ if (state->info.port.tty)
+ state->info.port.tty->low_latency =
(port->flags & UPF_LOW_LATENCY) ? 1 : 0;

check_and_exit:
retval = 0;
if (port->type == PORT_UNKNOWN)
goto exit;
- if (state->info->flags & UIF_INITIALIZED) {
+ if (state->info.flags & UIF_INITIALIZED) {
if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||
old_custom_divisor != port->custom_divisor) {
/*
@@ -858,7 +859,7 @@ static int uart_set_info(struct uart_state *state,
printk(KERN_NOTICE
"%s sets custom speed on %s. This "
"is deprecated.\n", current->comm,
- tty_name(state->info->port.tty, buf));
+ tty_name(state->info.port.tty, buf));
}
uart_change_speed(state, NULL);
}
@@ -889,8 +890,8 @@ static int uart_get_lsr_info(struct uart_state *state,
* interrupt happens).
*/
if (port->x_char ||
- ((uart_circ_chars_pending(&state->info->xmit) > 0) &&
- !state->info->port.tty->stopped && !state->info->port.tty->hw_stopped))
+ ((uart_circ_chars_pending(&state->info.xmit) > 0) &&
+ !state->info.port.tty->stopped && !state->info.port.tty->hw_stopped))
result &= ~TIOCSER_TEMT;

return put_user(result, value);
@@ -1017,7 +1018,7 @@ uart_wait_modem_status(struct uart_state *state, unsigned long arg)
port->ops->enable_ms(port);
spin_unlock_irq(&port->lock);

- add_wait_queue(&state->info->delta_msr_wait, &wait);
+ add_wait_queue(&state->info.delta_msr_wait, &wait);
for (;;) {
spin_lock_irq(&port->lock);
memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
@@ -1045,7 +1046,7 @@ uart_wait_modem_status(struct uart_state *state, unsigned long arg)
}

current->state = TASK_RUNNING;
- remove_wait_queue(&state->info->delta_msr_wait, &wait);
+ remove_wait_queue(&state->info.delta_msr_wait, &wait);

return ret;
}
@@ -1241,7 +1242,7 @@ static void uart_set_termios(struct tty_struct *tty,
*/
if (!(old_termios->c_cflag & CLOCAL) &&
(tty->termios->c_cflag & CLOCAL))
- wake_up_interruptible(&state->info->port.open_wait);
+ wake_up_interruptible(&info->port.open_wait);
#endif
}

@@ -1303,7 +1304,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
* At this point, we stop accepting input. To do this, we
* disable the receive line status interrupts.
*/
- if (state->info->flags & UIF_INITIALIZED) {
+ if (state->info.flags & UIF_INITIALIZED) {
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
port->ops->stop_rx(port);
@@ -1322,9 +1323,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
tty_ldisc_flush(tty);

tty->closing = 0;
- state->info->port.tty = NULL;
+ state->info.port.tty = NULL;

- if (state->info->port.blocked_open) {
+ if (state->info.port.blocked_open) {
if (state->close_delay)
msleep_interruptible(state->close_delay);
} else if (!uart_console(port)) {
@@ -1334,8 +1335,8 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
/*
* Wake up anyone trying to open this port.
*/
- state->info->flags &= ~UIF_NORMAL_ACTIVE;
- wake_up_interruptible(&state->info->port.open_wait);
+ state->info.flags &= ~UIF_NORMAL_ACTIVE;
+ wake_up_interruptible(&state->info.port.open_wait);

done:
mutex_unlock(&state->mutex);
@@ -1409,19 +1410,20 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
static void uart_hangup(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
+ struct uart_info *info = &state->info;

BUG_ON(!kernel_locked());
pr_debug("uart_hangup(%d)\n", state->port->line);

mutex_lock(&state->mutex);
- if (state->info && state->info->flags & UIF_NORMAL_ACTIVE) {
+ if (info->flags & UIF_NORMAL_ACTIVE) {
uart_flush_buffer(tty);
uart_shutdown(state);
state->count = 0;
- state->info->flags &= ~UIF_NORMAL_ACTIVE;
- state->info->port.tty = NULL;
- wake_up_interruptible(&state->info->port.open_wait);
- wake_up_interruptible(&state->info->delta_msr_wait);
+ info->flags &= ~UIF_NORMAL_ACTIVE;
+ info->port.tty = NULL;
+ wake_up_interruptible(&info->port.open_wait);
+ wake_up_interruptible(&info->delta_msr_wait);
}
mutex_unlock(&state->mutex);
}
@@ -1434,7 +1436,7 @@ static void uart_hangup(struct tty_struct *tty)
*/
static void uart_update_termios(struct uart_state *state)
{
- struct tty_struct *tty = state->info->port.tty;
+ struct tty_struct *tty = state->info.port.tty;
struct uart_port *port = state->port;

if (uart_console(port) && port->cons->cflag) {
@@ -1469,7 +1471,7 @@ static int
uart_block_til_ready(struct file *filp, struct uart_state *state)
{
DECLARE_WAITQUEUE(wait, current);
- struct uart_info *info = state->info;
+ struct uart_info *info = &state->info;
struct uart_port *port = state->port;
unsigned int mctrl;

@@ -1563,28 +1565,6 @@ static struct uart_state *uart_get(struct uart_driver *drv, int line)
ret = -ENXIO;
goto err_unlock;
}
-
- /* BKL: RACE HERE - LEAK */
- /* We should move this into the uart_state structure and kill off
- this whole complexity */
- if (!state->info) {
- state->info = kzalloc(sizeof(struct uart_info), GFP_KERNEL);
- if (state->info) {
- init_waitqueue_head(&state->info->port.open_wait);
- init_waitqueue_head(&state->info->delta_msr_wait);
-
- /*
- * Link the info into the other structures.
- */
- state->port->info = state->info;
-
- tasklet_init(&state->info->tlet, uart_tasklet_action,
- (unsigned long)state);
- } else {
- ret = -ENOMEM;
- goto err_unlock;
- }
- }
return state;

err_unlock:
@@ -1641,9 +1621,10 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
* Any failures from here onwards should not touch the count.
*/
tty->driver_data = state;
+ state->port->info = &state->info;
tty->low_latency = (state->port->flags & UPF_LOW_LATENCY) ? 1 : 0;
tty->alt_speed = 0;
- state->info->port.tty = tty;
+ state->info.port.tty = tty;

/*
* If the port is in the middle of closing, bail out now.
@@ -1676,8 +1657,8 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
/*
* If this is the first open to succeed, adjust things to suit.
*/
- if (retval == 0 && !(state->info->flags & UIF_NORMAL_ACTIVE)) {
- state->info->flags |= UIF_NORMAL_ACTIVE;
+ if (retval == 0 && !(state->info.flags & UIF_NORMAL_ACTIVE)) {
+ state->info.flags |= UIF_NORMAL_ACTIVE;

uart_update_termios(state);
}
@@ -2028,11 +2009,11 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
}
port->suspended = 1;

- if (state->info && state->info->flags & UIF_INITIALIZED) {
+ if (state->info.flags & UIF_INITIALIZED) {
const struct uart_ops *ops = port->ops;
int tries;

- state->info->flags = (state->info->flags & ~UIF_INITIALIZED)
+ state->info.flags = (state->info.flags & ~UIF_INITIALIZED)
| UIF_SUSPENDED;

spin_lock_irq(&port->lock);
@@ -2107,15 +2088,15 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
/*
* If that's unset, use the tty termios setting.
*/
- if (state->info && state->info->port.tty && termios.c_cflag == 0)
- termios = *state->info->port.tty->termios;
+ if (state->info.port.tty && termios.c_cflag == 0)
+ termios = *state->info.port.tty->termios;

uart_change_pm(state, 0);
port->ops->set_termios(port, &termios, NULL);
console_start(port->cons);
}

- if (state->info && state->info->flags & UIF_SUSPENDED) {
+ if (state->info.flags & UIF_SUSPENDED) {
const struct uart_ops *ops = port->ops;
int ret;

@@ -2130,7 +2111,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
ops->set_mctrl(port, port->mctrl);
ops->start_tx(port);
spin_unlock_irq(&port->lock);
- state->info->flags |= UIF_INITIALIZED;
+ state->info.flags |= UIF_INITIALIZED;
} else {
/*
* Failed to resume - maybe hardware went away?
@@ -2140,7 +2121,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
uart_shutdown(state);
}

- state->info->flags &= ~UIF_SUSPENDED;
+ state->info.flags &= ~UIF_SUSPENDED;
}

mutex_unlock(&state->mutex);
@@ -2383,8 +2364,12 @@ int uart_register_driver(struct uart_driver *drv)

state->close_delay = 500; /* .5 seconds */
state->closing_wait = 30000; /* 30 seconds */
-
mutex_init(&state->mutex);
+
+ tty_port_init(&state->info.port);
+ init_waitqueue_head(&state->info.delta_msr_wait);
+ tasklet_init(&state->info.tlet, uart_tasklet_action,
+ (unsigned long)state);
}

retval = tty_register_driver(normal);
@@ -2455,7 +2440,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
state->pm_state = -1;

port->cons = drv->cons;
- port->info = state->info;
+ port->info = &state->info;

/*
* If this port is a console, then the spinlock is already
@@ -2527,18 +2512,11 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
*/
tty_unregister_device(drv->tty_driver, port->line);

- info = state->info;
+ info = &state->info;
if (info && info->port.tty)
tty_vhangup(info->port.tty);

/*
- * All users of this port should now be disconnected from
- * this driver, and the port shut down. We should be the
- * only thread fiddling with this port from now on.
- */
- state->info = NULL;
-
- /*
* Free the port IO and memory resources, if any.
*/
if (port->type != PORT_UNKNOWN)
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index feb3b93..2395969 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -316,35 +316,13 @@ struct uart_port {
};

/*
- * This is the state information which is persistent across opens.
- * The low level driver must not to touch any elements contained
- * within.
- */
-struct uart_state {
- unsigned int close_delay; /* msec */
- unsigned int closing_wait; /* msec */
-
-#define USF_CLOSING_WAIT_INF (0)
-#define USF_CLOSING_WAIT_NONE (~0U)
-
- int count;
- int pm_state;
- struct uart_info *info;
- struct uart_port *port;
-
- struct mutex mutex;
-};
-
-#define UART_XMIT_SIZE PAGE_SIZE
-
-typedef unsigned int __bitwise__ uif_t;
-
-/*
* This is the state information which is only valid when the port
- * is open; it may be freed by the core driver once the device has
+ * is open; it may be cleared the core driver once the device has
* been closed. Either the low level driver or the core can modify
* stuff here.
*/
+typedef unsigned int __bitwise__ uif_t;
+
struct uart_info {
struct tty_port port;
struct circ_buf xmit;
@@ -366,6 +344,29 @@ struct uart_info {
wait_queue_head_t delta_msr_wait;
};

+/*
+ * This is the state information which is persistent across opens.
+ * The low level driver must not to touch any elements contained
+ * within.
+ */
+struct uart_state {
+ unsigned int close_delay; /* msec */
+ unsigned int closing_wait; /* msec */
+
+#define USF_CLOSING_WAIT_INF (0)
+#define USF_CLOSING_WAIT_NONE (~0U)
+
+ int count;
+ int pm_state;
+ struct uart_info info;
+ struct uart_port *port;
+
+ struct mutex mutex;
+};
+
+#define UART_XMIT_SIZE PAGE_SIZE
+
+
/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

@@ -439,8 +440,13 @@ int uart_resume_port(struct uart_driver *reg, struct uart_port *port);
#define uart_circ_chars_free(circ) \
(CIRC_SPACE((circ)->head, (circ)->tail, UART_XMIT_SIZE))

-#define uart_tx_stopped(portp) \
- ((portp)->info->port.tty->stopped || (portp)->info->port.tty->hw_stopped)
+static inline int uart_tx_stopped(struct uart_port *port)
+{
+ struct tty_struct *tty = port->info->port.tty;
+ if(tty->stopped || tty->hw_stopped)
+ return 1;
+ return 0;
+}

/*
* The following are helper functions for the low level drivers.
@@ -451,7 +457,7 @@ uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
#ifdef SUPPORT_SYSRQ
if (port->sysrq) {
if (ch && time_before(jiffies, port->sysrq)) {
- handle_sysrq(ch, port->info ? port->info->port.tty : NULL);
+ handle_sysrq(ch, port->info->port.tty);
port->sysrq = 0;
return 1;
}