--- zzzz-none-000/linux-3.10.107/drivers/tty/n_r3964.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/tty/n_r3964.c	2021-02-04 17:41:59.000000000 +0000
@@ -276,7 +276,7 @@
 			add_msg(pHeader->owner, R3964_MSG_ACK, pHeader->length,
 				error_code, NULL);
 		}
-		wake_up_interruptible(&pInfo->read_wait);
+		wake_up_interruptible(&pInfo->tty->read_wait);
 	}
 
 	spin_lock_irqsave(&pInfo->lock, flags);
@@ -542,7 +542,7 @@
 				pBlock);
 		}
 	}
-	wake_up_interruptible(&pInfo->read_wait);
+	wake_up_interruptible(&pInfo->tty->read_wait);
 
 	pInfo->state = R3964_IDLE;
 
@@ -978,8 +978,8 @@
 	}
 
 	spin_lock_init(&pInfo->lock);
+	mutex_init(&pInfo->read_lock);
 	pInfo->tty = tty;
-	init_waitqueue_head(&pInfo->read_wait);
 	pInfo->priority = R3964_MASTER;
 	pInfo->rx_first = pInfo->rx_last = NULL;
 	pInfo->tx_first = pInfo->tx_last = NULL;
@@ -1045,7 +1045,6 @@
 	}
 
 	/* Free buffers: */
-	wake_up_interruptible(&pInfo->read_wait);
 	kfree(pInfo->rx_buf);
 	TRACE_M("r3964_close - rx_buf kfree %p", pInfo->rx_buf);
 	kfree(pInfo->tx_buf);
@@ -1065,7 +1064,16 @@
 
 	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) {
@@ -1077,7 +1085,7 @@
 				goto unlock;
 			}
 			/* block until there is a message: */
-			wait_event_interruptible_tty(tty, pInfo->read_wait,
+			wait_event_interruptible(tty->read_wait,
 					(pMsg = remove_msg(pInfo, pClient)));
 		}
 
@@ -1107,7 +1115,7 @@
 	}
 	ret = -EPERM;
 unlock:
-	tty_unlock(tty);
+	mutex_unlock(&pInfo->read_lock);
 	return ret;
 }
 
@@ -1156,8 +1164,6 @@
 	pHeader->locks = 0;
 	pHeader->owner = NULL;
 
-	tty_lock(tty);
-
 	pClient = findClient(pInfo, task_pid(current));
 	if (pClient) {
 		pHeader->owner = pClient;
@@ -1175,8 +1181,6 @@
 	add_tx_queue(pInfo, pHeader);
 	trigger_transmit(pInfo);
 
-	tty_unlock(tty);
-
 	return 0;
 }
 
@@ -1227,7 +1231,7 @@
 
 	pClient = findClient(pInfo, task_pid(current));
 	if (pClient) {
-		poll_wait(file, &pInfo->read_wait, wait);
+		poll_wait(file, &tty->read_wait, wait);
 		spin_lock_irqsave(&pInfo->lock, flags);
 		pMsg = pClient->first_msg;
 		spin_unlock_irqrestore(&pInfo->lock, flags);
@@ -1244,7 +1248,7 @@
 {
 	struct r3964_info *pInfo = tty->disc_data;
 	const unsigned char *p;
-	char *f, flags = 0;
+	char *f, flags = TTY_NORMAL;
 	int i;
 
 	for (i = count, p = cp, f = fp; i; i--, p++) {