TTY/Serial fixes for 5.0-rc6

Here are some small tty and serial fixes for 5.0-rc6.
 
 Nothing huge, just a few small fixes for reported issues.  The speakup
 fix is in here as it is a tty operation issue.
 
 All of these have been in linux-next for a while with no reported
 problems.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some small tty and serial fixes for 5.0-rc6.

  Nothing huge, just a few small fixes for reported issues. The speakup
  fix is in here as it is a tty operation issue.

  All of these have been in linux-next for a while with no reported
  problems"

* tag 'tty-5.0-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: fix race between flush_to_ldisc and tty_open
  staging: speakup: fix tty-operation NULL derefs
  serial: sh-sci: Do not free irqs that have already been freed
  serial: 8250_pci: Make PCI class test non fatal
  tty: serial: 8250_mtk: Fix potential NULL pointer dereference

drivers/staging/speakup/spk_ttyio.c

@@ -265,7 +265,8 @@ static void spk_ttyio_send_xchar(char ch)
 		return;
 	}
 
-	speakup_tty->ops->send_xchar(speakup_tty, ch);
+	if (speakup_tty->ops->send_xchar)
+		speakup_tty->ops->send_xchar(speakup_tty, ch);
 	mutex_unlock(&speakup_tty_mutex);
 }
 
@@ -277,7 +278,8 @@ static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear)
 		return;
 	}
 
-	speakup_tty->ops->tiocmset(speakup_tty, set, clear);
+	if (speakup_tty->ops->tiocmset)
+		speakup_tty->ops->tiocmset(speakup_tty, set, clear);
 	mutex_unlock(&speakup_tty_mutex);
 }
 

drivers/tty/serial/8250/8250_mtk.c

@@ -357,6 +357,9 @@ static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
 	if (dmacnt == 2) {
 		data->dma = devm_kzalloc(&pdev->dev, sizeof(*data->dma),
 					 GFP_KERNEL);
+		if (!data->dma)
+			return -ENOMEM;
+
 		data->dma->fn = mtk8250_dma_filter;
 		data->dma->rx_size = MTK_UART_RX_SIZE;
 		data->dma->rxconf.src_maxburst = MTK_UART_RX_TRIGGER;

drivers/tty/serial/8250/8250_pci.c

@@ -3420,6 +3420,11 @@ static int
 serial_pci_guess_board(struct pci_dev *dev, struct pciserial_board *board)
 {
 	int num_iomem, num_port, first_port = -1, i;
+	int rc;
+
+	rc = serial_pci_is_class_communication(dev);
+	if (rc)
+		return rc;
 
 	/*
 	 * Should we try to make guesses for multiport serial devices later?
@@ -3647,10 +3652,6 @@ pciserial_init_one(struct pci_dev *dev, const struct pci_device_id *ent)
 
 	board = &pci_boards[ent->driver_data];
 
-	rc = serial_pci_is_class_communication(dev);
-	if (rc)
-		return rc;
-
 	rc = serial_pci_is_blacklisted(dev);
 	if (rc)
 		return rc;

drivers/tty/serial/serial_core.c

@@ -130,6 +130,9 @@ static void uart_start(struct tty_struct *tty)
 	struct uart_port *port;
 	unsigned long flags;
 
+	if (!state)
+		return;
+
 	port = uart_port_lock(state, flags);
 	__uart_start(tty);
 	uart_port_unlock(port, flags);
@@ -727,6 +730,9 @@ static void uart_unthrottle(struct tty_struct *tty)
 	upstat_t mask = UPSTAT_SYNC_FIFO;
 	struct uart_port *port;
 
+	if (!state)
+		return;
+
 	port = uart_port_ref(state);
 	if (!port)
 		return;

drivers/tty/serial/sh-sci.c

@@ -1921,7 +1921,7 @@ out_nomem:
 
 static void sci_free_irq(struct sci_port *port)
 {
-	int i;
+	int i, j;
 
 	/*
 	 * Intentionally in reverse order so we iterate over the muxed
@@ -1937,6 +1937,13 @@ static void sci_free_irq(struct sci_port *port)
 		if (unlikely(irq < 0))
 			continue;
 
+		/* Check if already freed (irq was muxed) */
+		for (j = 0; j < i; j++)
+			if (port->irqs[j] == irq)
+				j = i + 1;
+		if (j > i)
+			continue;
+
 		free_irq(port->irqs[i], port);
 		kfree(port->irqstr[i]);