diff --git a/drivers/tty/n_r3964.c b/drivers/tty/n_r3964.c
index 6fdef921cdb7..345111467b85 100644
--- a/drivers/tty/n_r3964.c
+++ b/drivers/tty/n_r3964.c
@@ -978,6 +978,7 @@ static int r3964_open(struct tty_struct *tty)
 	}
 
 	spin_lock_init(&pInfo->lock);
+	mutex_init(&pInfo->read_lock);
 	pInfo->tty = tty;
 	pInfo->priority = R3964_MASTER;
 	pInfo->rx_first = pInfo->rx_last = NULL;
@@ -1063,7 +1064,16 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 
 	TRACE_L("read()");
 
-	tty_lock(tty);
+	/*
+	 *	Internal serialization of reads.
+	 */
+	if (file->f_flags & O_NONBLOCK) {
+		if (!mutex_trylock(&pInfo->read_lock))
+			return -EAGAIN;
+	} else {
+		if (mutex_lock_interruptible(&pInfo->read_lock))
+			return -ERESTARTSYS;
+	}
 
 	pClient = findClient(pInfo, task_pid(current));
 	if (pClient) {
@@ -1075,7 +1085,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 				goto unlock;
 			}
 			/* block until there is a message: */
-			wait_event_interruptible_tty(tty, tty->read_wait,
+			wait_event_interruptible(tty->read_wait,
 					(pMsg = remove_msg(pInfo, pClient)));
 		}
 
@@ -1105,7 +1115,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 	}
 	ret = -EPERM;
 unlock:
-	tty_unlock(tty);
+	mutex_unlock(&pInfo->read_lock);
 	return ret;
 }
 
@@ -1154,8 +1164,6 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
 	pHeader->locks = 0;
 	pHeader->owner = NULL;
 
-	tty_lock(tty);
-
 	pClient = findClient(pInfo, task_pid(current));
 	if (pClient) {
 		pHeader->owner = pClient;
@@ -1173,8 +1181,6 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
 	add_tx_queue(pInfo, pHeader);
 	trigger_transmit(pInfo);
 
-	tty_unlock(tty);
-
 	return 0;
 }
 
diff --git a/include/linux/n_r3964.h b/include/linux/n_r3964.h
index e9adb4226224..90a803aa42e8 100644
--- a/include/linux/n_r3964.h
+++ b/include/linux/n_r3964.h
@@ -161,8 +161,9 @@ struct r3964_info {
 	unsigned char last_rx;
 	unsigned char bcc;
         unsigned int  blocks_in_rx_queue;
-	  
-	
+
+	struct mutex read_lock;		/* serialize r3964_read */
+
 	struct r3964_client_info *firstClient;
 	unsigned int state;
 	unsigned int flags;