tty: We want the port object to be persistent

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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 62 insertions, 84 deletions

diff --git a/drivers/serial/jsm/jsm_tty.c b/drivers/serial/jsm/jsm_tty.c
index a697914ae3d0..3547558d2caf 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 874786a11fe9..daeba1c52c8e 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)