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Subject[PATCH 28/58] sdio_uart: refcount the tty objects
Date
From: Alan Cox <alan@linux.intel.com>

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>
---
drivers/mmc/card/sdio_uart.c | 59 +++++++++++++++++++++++++++++------------
1 files changed, 42 insertions(+), 17 deletions(-)
diff --git a/drivers/mmc/card/sdio_uart.c b/drivers/mmc/card/sdio_uart.c
index 671fe5e..86ad543 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;
}
--
1.6.5.5
--
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