USB: serial: cyberjack: use irqsave() in USB's complete callback

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/cyberjack.c

@@ -255,6 +255,7 @@ static void cyberjack_read_int_callback(struct urb *urb)
 	struct device *dev = &port->dev;
 	unsigned char *data = urb->transfer_buffer;
 	int status = urb->status;
+	unsigned long flags;
 	int result;
 
 	/* the urb might have been killed. */
@@ -270,13 +271,13 @@ static void cyberjack_read_int_callback(struct urb *urb)
 		/* This is a announcement of coming bulk_ins. */
 		unsigned short size = ((unsigned short)data[3]<<8)+data[2]+3;
 
-		spin_lock(&priv->lock);
+		spin_lock_irqsave(&priv->lock, flags);
 
 		old_rdtodo = priv->rdtodo;
 
 		if (old_rdtodo > SHRT_MAX - size) {
 			dev_dbg(dev, "To many bulk_in urbs to do.\n");
-			spin_unlock(&priv->lock);
+			spin_unlock_irqrestore(&priv->lock, flags);
 			goto resubmit;
 		}
 
@@ -285,7 +286,7 @@ static void cyberjack_read_int_callback(struct urb *urb)
 
 		dev_dbg(dev, "%s - rdtodo: %d\n", __func__, priv->rdtodo);
 
-		spin_unlock(&priv->lock);
+		spin_unlock_irqrestore(&priv->lock, flags);
 
 		if (!old_rdtodo) {
 			result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
@@ -309,6 +310,7 @@ static void cyberjack_read_bulk_callback(struct urb *urb)
 	struct cyberjack_private *priv = usb_get_serial_port_data(port);
 	struct device *dev = &port->dev;
 	unsigned char *data = urb->transfer_buffer;
+	unsigned long flags;
 	short todo;
 	int result;
 	int status = urb->status;
@@ -325,7 +327,7 @@ static void cyberjack_read_bulk_callback(struct urb *urb)
 		tty_flip_buffer_push(&port->port);
 	}
 
-	spin_lock(&priv->lock);
+	spin_lock_irqsave(&priv->lock, flags);
 
 	/* Reduce urbs to do by one. */
 	priv->rdtodo -= urb->actual_length;
@@ -334,7 +336,7 @@ static void cyberjack_read_bulk_callback(struct urb *urb)
 		priv->rdtodo = 0;
 	todo = priv->rdtodo;
 
-	spin_unlock(&priv->lock);
+	spin_unlock_irqrestore(&priv->lock, flags);
 
 	dev_dbg(dev, "%s - rdtodo: %d\n", __func__, todo);
 
@@ -354,6 +356,7 @@ static void cyberjack_write_bulk_callback(struct urb *urb)
 	struct cyberjack_private *priv = usb_get_serial_port_data(port);
 	struct device *dev = &port->dev;
 	int status = urb->status;
+	unsigned long flags;
 
 	set_bit(0, &port->write_urbs_free);
 	if (status) {
@@ -362,7 +365,7 @@ static void cyberjack_write_bulk_callback(struct urb *urb)
 		return;
 	}
 
-	spin_lock(&priv->lock);
+	spin_lock_irqsave(&priv->lock, flags);
 
 	/* only do something if we have more data to send */
 	if (priv->wrfilled) {
@@ -406,7 +409,7 @@ static void cyberjack_write_bulk_callback(struct urb *urb)
 	}
 
 exit:
-	spin_unlock(&priv->lock);
+	spin_unlock_irqrestore(&priv->lock, flags);
 	usb_serial_port_softint(port);
 }