[PATCH 2/2] hso: fix deadlock when receiving bursts of data

@@ -106,6 +106,8 @@
 
 #define MAX_RX_URBS			2
 
+#define UNTHROTTLE_TIMEOUT		100 /* msecs */
+
 /*****************************************************************************/
 /* Debugging functions                                                       */
 /*****************************************************************************/

@@ -261,6 +263,7 @@ struct hso_serial {
 	u16  curr_rx_urb_offset;
 	u8   rx_urb_filled[MAX_RX_URBS];
 	struct tasklet_struct unthrottle_tasklet;
+	struct timer_list unthrottle_timer;
 };
 
 struct hso_device {

@@ -1161,13 +1164,18 @@ static void put_rxbuf_data_and_resubmit_bulk_urb(struct hso_serial *serial)
 	while (serial->rx_urb_filled[serial->curr_rx_urb_idx]) {
 		curr_urb = serial->rx_urb[serial->curr_rx_urb_idx];
 		count = put_rxbuf_data(curr_urb, serial);
-		if (count == -1)
-			return;
 		if (count == 0) {
 			serial->curr_rx_urb_idx++;
 			if (serial->curr_rx_urb_idx >= serial->num_rx_urbs)
 				serial->curr_rx_urb_idx = 0;
 			hso_resubmit_rx_bulk_urb(serial, curr_urb);
+		} else if (count > 0) {
+			mod_timer(&serial->unthrottle_timer,
+				  jiffies
+					+ msecs_to_jiffies(UNTHROTTLE_TIMEOUT));
+			break;
+		} else {
+			break;
 		}
 	}
 }

@@ -1251,6 +1259,11 @@ static	void hso_unthrottle(struct tty_struct *tty)
 	tasklet_hi_schedule(&serial->unthrottle_tasklet);
 }
 
+static void hso_unthrottle_schedule(unsigned long data)
+{
+	tasklet_schedule((struct tasklet_struct *)data);
+}
+
 /* open the requested serial port */
 static int hso_serial_open(struct tty_struct *tty, struct file *filp)
 {

@@ -1286,6 +1299,10 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
 		tasklet_init(&serial->unthrottle_tasklet,
 			     (void (*)(unsigned long))hso_unthrottle_tasklet,
 			     (unsigned long)serial);
+		serial->unthrottle_timer.function = hso_unthrottle_schedule;
+		serial->unthrottle_timer.data =
+				(unsigned long)&serial->unthrottle_tasklet;
+		init_timer(&serial->unthrottle_timer);
 		result = hso_start_serial_device(serial->parent, GFP_KERNEL);
 		if (result) {
 			hso_stop_serial_device(serial->parent);

@@ -1333,6 +1350,7 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
 		tty_port_tty_set(&serial->port, NULL);
 		if (!usb_gone)
 			hso_stop_serial_device(serial->parent);
+		del_timer_sync(&serial->unthrottle_timer);
 		tasklet_kill(&serial->unthrottle_tasklet);
 	}
 

@@ -2012,22 +2030,23 @@ static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial)
 
 	tty = tty_port_tty_get(&serial->port);
 
+	if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {
+		tty_kref_put(tty);
+		return -1;
+	}
+
 	/* Push data to tty */
-	write_length_remaining = urb->actual_length -
-		serial->curr_rx_urb_offset;
 	D1("data to push to tty");
-	while (write_length_remaining) {
-		if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {
-			tty_kref_put(tty);
-			return -1;
-		}
-		curr_write_len = tty_insert_flip_string(&serial->port,
-			urb->transfer_buffer + serial->curr_rx_urb_offset,
-			write_length_remaining);
-		serial->curr_rx_urb_offset += curr_write_len;
-		write_length_remaining -= curr_write_len;
-		tty_flip_buffer_push(&serial->port);
-	}
+	write_length_remaining = urb->actual_length -
+					serial->curr_rx_urb_offset;
+	curr_write_len =
+		tty_insert_flip_string(&serial->port,
+				       urb->transfer_buffer
+						+ serial->curr_rx_urb_offset,
+				       write_length_remaining);
+	serial->curr_rx_urb_offset += curr_write_len;
+	write_length_remaining -= curr_write_len;
+	tty_flip_buffer_push(&serial->port);
 	tty_kref_put(tty);
 
 	if (write_length_remaining == 0) {