USB: serial: digi_acceleport: 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/digi_acceleport.c

@@ -984,6 +984,7 @@ static void digi_write_bulk_callback(struct urb *urb)
 	struct usb_serial *serial;
 	struct digi_port *priv;
 	struct digi_serial *serial_priv;
+	unsigned long flags;
 	int ret = 0;
 	int status = urb->status;
 
@@ -1004,15 +1005,15 @@ static void digi_write_bulk_callback(struct urb *urb)
 	/* handle oob callback */
 	if (priv->dp_port_num == serial_priv->ds_oob_port_num) {
 		dev_dbg(&port->dev, "digi_write_bulk_callback: oob callback\n");
-		spin_lock(&priv->dp_port_lock);
+		spin_lock_irqsave(&priv->dp_port_lock, flags);
 		priv->dp_write_urb_in_use = 0;
 		wake_up_interruptible(&port->write_wait);
-		spin_unlock(&priv->dp_port_lock);
+		spin_unlock_irqrestore(&priv->dp_port_lock, flags);
 		return;
 	}
 
 	/* try to send any buffered data on this port */
-	spin_lock(&priv->dp_port_lock);
+	spin_lock_irqsave(&priv->dp_port_lock, flags);
 	priv->dp_write_urb_in_use = 0;
 	if (priv->dp_out_buf_len > 0) {
 		*((unsigned char *)(port->write_urb->transfer_buffer))
@@ -1035,7 +1036,7 @@ static void digi_write_bulk_callback(struct urb *urb)
 	/* lost the race in write_chan(). */
 	schedule_work(&priv->dp_wakeup_work);
 
-	spin_unlock(&priv->dp_port_lock);
+	spin_unlock_irqrestore(&priv->dp_port_lock, flags);
 	if (ret && ret != -EPERM)
 		dev_err_console(port,
 			"%s: usb_submit_urb failed, ret=%d, port=%d\n",
@@ -1381,6 +1382,7 @@ static int digi_read_inb_callback(struct urb *urb)
 	struct usb_serial_port *port = urb->context;
 	struct digi_port *priv = usb_get_serial_port_data(port);
 	unsigned char *buf = urb->transfer_buffer;
+	unsigned long flags;
 	int opcode;
 	int len;
 	int port_status;
@@ -1407,7 +1409,7 @@ static int digi_read_inb_callback(struct urb *urb)
 		return -1;
 	}
 
-	spin_lock(&priv->dp_port_lock);
+	spin_lock_irqsave(&priv->dp_port_lock, flags);
 
 	/* check for throttle; if set, do not resubmit read urb */
 	/* indicate the read chain needs to be restarted on unthrottle */
@@ -1444,7 +1446,7 @@ static int digi_read_inb_callback(struct urb *urb)
 			tty_flip_buffer_push(&port->port);
 		}
 	}
-	spin_unlock(&priv->dp_port_lock);
+	spin_unlock_irqrestore(&priv->dp_port_lock, flags);
 
 	if (opcode == DIGI_CMD_RECEIVE_DISABLE)
 		dev_dbg(&port->dev, "%s: got RECEIVE_DISABLE\n", __func__);
@@ -1474,6 +1476,7 @@ static int digi_read_oob_callback(struct urb *urb)
 	struct digi_port *priv = usb_get_serial_port_data(port);
 	unsigned char *buf = urb->transfer_buffer;
 	int opcode, line, status, val;
+	unsigned long flags;
 	int i;
 	unsigned int rts;
 
@@ -1506,7 +1509,7 @@ static int digi_read_oob_callback(struct urb *urb)
 			rts = C_CRTSCTS(tty);
 
 		if (tty && opcode == DIGI_CMD_READ_INPUT_SIGNALS) {
-			spin_lock(&priv->dp_port_lock);
+			spin_lock_irqsave(&priv->dp_port_lock, flags);
 			/* convert from digi flags to termiox flags */
 			if (val & DIGI_READ_INPUT_SIGNALS_CTS) {
 				priv->dp_modem_signals |= TIOCM_CTS;
@@ -1530,12 +1533,12 @@ static int digi_read_oob_callback(struct urb *urb)
 			else
 				priv->dp_modem_signals &= ~TIOCM_CD;
 
-			spin_unlock(&priv->dp_port_lock);
+			spin_unlock_irqrestore(&priv->dp_port_lock, flags);
 		} else if (opcode == DIGI_CMD_TRANSMIT_IDLE) {
-			spin_lock(&priv->dp_port_lock);
+			spin_lock_irqsave(&priv->dp_port_lock, flags);
 			priv->dp_transmit_idle = 1;
 			wake_up_interruptible(&priv->dp_transmit_idle_wait);
-			spin_unlock(&priv->dp_port_lock);
+			spin_unlock_irqrestore(&priv->dp_port_lock, flags);
 		} else if (opcode == DIGI_CMD_IFLUSH_FIFO) {
 			wake_up_interruptible(&priv->dp_flush_wait);
 		}