sdio_uart: refcount the tty objects

The tty can go away underneath us, so we must refcount it. Do the naïve
implementation initially. We will worry about startup shortly.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/mmc/card/sdio_uart.c b/drivers/mmc/card/sdio_uart.c
index 671fe5e..86ad543 100644 (file)
--- a/drivers/mmc/card/sdio_uart.c
+++ b/drivers/mmc/card/sdio_uart.c
@@ -172,8 +172,13 @@ static void sdio_uart_port_remove(struct sdio_uart_port *port)
        sdio_claim_host(func);
        port->func = NULL;
        mutex_unlock(&port->func_lock);
-       if (port->opened)
-               tty_hangup(port->port.tty);
+       if (port->opened) {
+               struct tty_struct *tty = tty_port_tty_get(&port->port);
+               /* tty_hangup is async so is this safe as is ?? */
+               if (tty)
+                       tty_hangup(tty);
+               tty_kref_put(tty);
+       }
        mutex_unlock(&port->open_lock);
        sdio_release_irq(func);
        sdio_disable_func(func);
@@ -392,7 +397,7 @@ static void sdio_uart_stop_rx(struct sdio_uart_port *port)
 static void sdio_uart_receive_chars(struct sdio_uart_port *port,
                                    unsigned int *status)
 {
-       struct tty_struct *tty = port->port.tty;
+       struct tty_struct *tty = tty_port_tty_get(&port->port);
        unsigned int ch, flag;
        int max_count = 256;
 
@@ -429,25 +434,30 @@ static void sdio_uart_receive_chars(struct sdio_uart_port *port,
                }
 
                if ((*status & port->ignore_status_mask & ~UART_LSR_OE) == 0)
-                       tty_insert_flip_char(tty, ch, flag);
+                       if (tty)
+                               tty_insert_flip_char(tty, ch, flag);
 
                /*
                 * Overrun is special.  Since it's reported immediately,
                 * it doesn't affect the current character.
                 */
                if (*status & ~port->ignore_status_mask & UART_LSR_OE)
-                       tty_insert_flip_char(tty, 0, TTY_OVERRUN);
+                       if (tty)
+                               tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 
                *status = sdio_in(port, UART_LSR);
        } while ((*status & UART_LSR_DR) && (max_count-- > 0));
-       tty_flip_buffer_push(tty);
+       if (tty) {
+               tty_flip_buffer_push(tty);
+               tty_kref_put(tty);
+       }
 }
 
 static void sdio_uart_transmit_chars(struct sdio_uart_port *port)
 {
        struct circ_buf *xmit = &port->xmit;
        int count;
-       struct tty_struct *tty = port->port.tty;
+       struct tty_struct *tty;
 
        if (port->x_char) {
                sdio_out(port, UART_TX, port->x_char);
@@ -455,8 +465,12 @@ static void sdio_uart_transmit_chars(struct sdio_uart_port *port)
                port->x_char = 0;
                return;
        }
-       if (circ_empty(xmit) || tty->stopped || tty->hw_stopped) {
+
+       tty = tty_port_tty_get(&port->port);
+
+       if (tty == NULL || circ_empty(xmit) || tty->stopped || tty->hw_stopped) {
                sdio_uart_stop_tx(port);
+               tty_kref_put(tty);
                return;
        }
 
@@ -474,12 +488,13 @@ static void sdio_uart_transmit_chars(struct sdio_uart_port *port)
 
        if (circ_empty(xmit))
                sdio_uart_stop_tx(port);
+       tty_kref_put(tty);
 }
 
 static void sdio_uart_check_modem_status(struct sdio_uart_port *port)
 {
        int status;
-       struct tty_struct *tty = port->port.tty;
+       struct tty_struct *tty;
 
        status = sdio_in(port, UART_MSR);
 
@@ -494,7 +509,8 @@ static void sdio_uart_check_modem_status(struct sdio_uart_port *port)
                port->icount.dcd++;
        if (status & UART_MSR_DCTS) {
                port->icount.cts++;
-               if (tty->termios->c_cflag & CRTSCTS) {
+               tty = tty_port_tty_get(&port->port);
+               if (tty && (tty->termios->c_cflag & CRTSCTS)) {
                        int cts = (status & UART_MSR_CTS);
                        if (tty->hw_stopped) {
                                if (cts) {
@@ -509,6 +525,7 @@ static void sdio_uart_check_modem_status(struct sdio_uart_port *port)
                                }
                        }
                }
+               tty_kref_put(tty);
        }
 }
 
@@ -548,8 +565,10 @@ static void sdio_uart_irq(struct sdio_func *func)
 static int sdio_uart_startup(struct sdio_uart_port *port)
 {
        unsigned long page;
-       int ret;
-       struct tty_struct *tty = port->port.tty;
+       int ret = -ENOMEM;
+       struct tty_struct *tty = tty_port_tty_get(&port->port);
+
+       /* FIXME: What if it is NULL ?? */
 
        /*
         * Set the TTY IO error marker - we will only clear this
@@ -560,7 +579,7 @@ static int sdio_uart_startup(struct sdio_uart_port *port)
        /* Initialise and allocate the transmit buffer. */
        page = __get_free_page(GFP_KERNEL);
        if (!page)
-               return -ENOMEM;
+               goto err0;
        port->xmit.buf = (unsigned char *)page;
        circ_clear(&port->xmit);
 
@@ -614,6 +633,7 @@ static int sdio_uart_startup(struct sdio_uart_port *port)
        sdio_uart_irq(port->func);
 
        sdio_uart_release_func(port);
+       tty_kref_put(tty);
        return 0;
 
 err3:
@@ -622,12 +642,15 @@ err2:
        sdio_uart_release_func(port);
 err1:
        free_page((unsigned long)port->xmit.buf);
+err0:
+       tty_kref_put(tty);
        return ret;
 }
 
 static void sdio_uart_shutdown(struct sdio_uart_port *port)
 {
        int ret;
+       struct tty_struct *tty;
 
        ret = sdio_uart_claim_func(port);
        if (ret)
@@ -637,9 +660,11 @@ static void sdio_uart_shutdown(struct sdio_uart_port *port)
 
        /* TODO: wait here for TX FIFO to drain */
 
+       tty = tty_port_tty_get(&port->port);
        /* Turn off DTR and RTS early. */
-       if (port->port.tty->termios->c_cflag & HUPCL)
+       if (tty && (tty->termios->c_cflag & HUPCL))
                sdio_uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
+       tty_kref_put(tty);
 
        /* Disable interrupts from this port */
        sdio_release_irq(port->func);
@@ -688,11 +713,11 @@ static int sdio_uart_open(struct tty_struct *tty, struct file *filp)
 
        if (!port->opened) {
                tty->driver_data = port;
-               port->port.tty = tty;
+               tty_port_tty_set(&port->port, tty);
                ret = sdio_uart_startup(port);
                if (ret) {
                        tty->driver_data = NULL;
-                       port->port.tty = NULL;
+                       tty_port_tty_set(&port->port, NULL);
                        mutex_unlock(&port->open_lock);
                        sdio_uart_port_put(port);
                        return ret;
@@ -727,7 +752,7 @@ static void sdio_uart_close(struct tty_struct *tty, struct file * filp)
                tty->closing = 1;
                sdio_uart_shutdown(port);
                tty_ldisc_flush(tty);
-               port->port.tty = NULL;
+               tty_port_tty_set(&port->port, NULL);
                tty->driver_data = NULL;
                tty->closing = 0;
        }