tty: usb-serial krefs

Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.

Contains two err->dev_err changes merged together to fix clashes in the
-next tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 29 insertions, 14 deletions

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index bfa508ddb0fe..611f97fd62f1 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -600,6 +600,7 @@ static void edge_interrupt_callback(struct urb *urb)
 	struct edgeport_serial	*edge_serial = urb->context;
 	struct edgeport_port *edge_port;
 	struct usb_serial_port *port;
+	struct tty_struct *tty;
 	unsigned char *data = urb->transfer_buffer;
 	int length = urb->actual_length;
 	int bytes_avail;
@@ -675,9 +676,12 @@ static void edge_interrupt_callback(struct urb *urb)
 
 					/* tell the tty driver that something
 					   has changed */
-					if (edge_port->port->port.tty)
-						tty_wakeup(edge_port->port->port.tty);
-
+					tty = tty_port_tty_get(
+						&edge_port->port->port);
+					if (tty) {
+						tty_wakeup(tty);
+						tty_kref_put(tty);
+					}
 					/* Since we have more credit, check
 					   if more data can be sent */
 					send_more_port_data(edge_serial,
@@ -778,13 +782,14 @@ static void edge_bulk_out_data_callback(struct urb *urb)
 		    __func__, status);
 	}
 
-	tty = edge_port->port->port.tty;
+	tty = tty_port_tty_get(&edge_port->port->port);
 
 	if (tty && edge_port->open) {
 		/* let the tty driver wakeup if it has a special
 		   write_wakeup function */
 		tty_wakeup(tty);
 	}
+	tty_kref_put(tty);
 
 	/* Release the Write URB */
 	edge_port->write_in_progress = false;
@@ -826,11 +831,12 @@ static void edge_bulk_out_cmd_callback(struct urb *urb)
 	}
 
 	/* Get pointer to tty */
-	tty = edge_port->port->port.tty;
+	tty = tty_port_tty_get(&edge_port->port->port);
 
 	/* tell the tty driver that something has changed */
 	if (tty && edge_port->open)
 		tty_wakeup(tty);
+	tty_kref_put(tty);
 
 	/* we have completed the command */
 	edge_port->commandPending = false;
@@ -1932,11 +1938,13 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial,
 							edge_serial->rxPort];
 				edge_port = usb_get_serial_port_data(port);
 				if (edge_port->open) {
-					tty = edge_port->port->port.tty;
+					tty = tty_port_tty_get(
+						&edge_port->port->port);
 					if (tty) {
 						dbg("%s - Sending %d bytes to TTY for port %d",
 							__func__, rxLen, edge_serial->rxPort);
 						edge_tty_recv(&edge_serial->serial->dev->dev, tty, buffer, rxLen);
+						tty_kref_put(tty);
 					}
 					edge_port->icount.rx += rxLen;
 				}
@@ -1971,6 +1979,7 @@ static void process_rcvd_status(struct edgeport_serial *edge_serial,
 {
 	struct usb_serial_port *port;
 	struct edgeport_port *edge_port;
+	struct tty_struct *tty;
 	__u8 code = edge_serial->rxStatusCode;
 
 	/* switch the port pointer to the one being currently talked about */
@@ -2020,10 +2029,12 @@ static void process_rcvd_status(struct edgeport_serial *edge_serial,
 
 		/* send the current line settings to the port so we are
 		   in sync with any further termios calls */
-		/* FIXME: locking on tty */
-		if (edge_port->port->port.tty)
-			change_port_settings(edge_port->port->port.tty,
-				edge_port, edge_port->port->port.tty->termios);
+		tty = tty_port_tty_get(&edge_port->port->port);
+		if (tty) {
+			change_port_settings(tty,
+				edge_port, tty->termios);
+			tty_kref_put(tty);
+		}
 
 		/* we have completed the open */
 		edge_port->openPending = false;
@@ -2163,10 +2174,14 @@ static void handle_new_lsr(struct edgeport_port *edge_port, __u8 lsrData,
 	}
 
 	/* Place LSR data byte into Rx buffer */
-	if (lsrData && edge_port->port->port.tty)
-		edge_tty_recv(&edge_port->port->dev,
-					edge_port->port->port.tty, &data, 1);
-
+	if (lsrData) {
+		struct tty_struct *tty =
+				tty_port_tty_get(&edge_port->port->port);
+		if (tty) {
+			edge_tty_recv(&edge_port->port->dev, tty, &data, 1);
+			tty_kref_put(tty);
+		}
+	}
 	/* update input line counters */
 	icount = &edge_port->icount;
 	if (newLsr & LSR_BREAK)