USB: serial: io_edgeport: 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/io_edgeport.c

@@ -648,6 +648,7 @@ static void edge_interrupt_callback(struct urb *urb)
 	struct usb_serial_port *port;
 	unsigned char *data = urb->transfer_buffer;
 	int length = urb->actual_length;
+	unsigned long flags;
 	int bytes_avail;
 	int position;
 	int txCredits;
@@ -679,7 +680,7 @@ static void edge_interrupt_callback(struct urb *urb)
 		if (length > 1) {
 			bytes_avail = data[0] | (data[1] << 8);
 			if (bytes_avail) {
-				spin_lock(&edge_serial->es_lock);
+				spin_lock_irqsave(&edge_serial->es_lock, flags);
 				edge_serial->rxBytesAvail += bytes_avail;
 				dev_dbg(dev,
 					"%s - bytes_avail=%d, rxBytesAvail=%d, read_in_progress=%d\n",
@@ -702,7 +703,8 @@ static void edge_interrupt_callback(struct urb *urb)
 						edge_serial->read_in_progress = false;
 					}
 				}
-				spin_unlock(&edge_serial->es_lock);
+				spin_unlock_irqrestore(&edge_serial->es_lock,
+						       flags);
 			}
 		}
 		/* grab the txcredits for the ports if available */
@@ -715,9 +717,11 @@ static void edge_interrupt_callback(struct urb *urb)
 				port = edge_serial->serial->port[portNumber];
 				edge_port = usb_get_serial_port_data(port);
 				if (edge_port->open) {
-					spin_lock(&edge_port->ep_lock);
+					spin_lock_irqsave(&edge_port->ep_lock,
+							  flags);
 					edge_port->txCredits += txCredits;
-					spin_unlock(&edge_port->ep_lock);
+					spin_unlock_irqrestore(&edge_port->ep_lock,
+							       flags);
 					dev_dbg(dev, "%s - txcredits for port%d = %d\n",
 						__func__, portNumber,
 						edge_port->txCredits);
@@ -758,6 +762,7 @@ static void edge_bulk_in_callback(struct urb *urb)
 	int			retval;
 	__u16			raw_data_length;
 	int status = urb->status;
+	unsigned long flags;
 
 	if (status) {
 		dev_dbg(&urb->dev->dev, "%s - nonzero read bulk status received: %d\n",
@@ -777,7 +782,7 @@ static void edge_bulk_in_callback(struct urb *urb)
 
 	usb_serial_debug_data(dev, __func__, raw_data_length, data);
 
-	spin_lock(&edge_serial->es_lock);
+	spin_lock_irqsave(&edge_serial->es_lock, flags);
 
 	/* decrement our rxBytes available by the number that we just got */
 	edge_serial->rxBytesAvail -= raw_data_length;
@@ -801,7 +806,7 @@ static void edge_bulk_in_callback(struct urb *urb)
 		edge_serial->read_in_progress = false;
 	}
 
-	spin_unlock(&edge_serial->es_lock);
+	spin_unlock_irqrestore(&edge_serial->es_lock, flags);
 }