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>

1 files changed, 42 insertions, 17 deletions

diff --git a/drivers/mmc/card/sdio_uart.c b/drivers/mmc/card/sdio_uart.c
index 671fe5efabf3..86ad54341128 100644
--- 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;
         }