Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/xen/xen-pciback/conf_space_capability.c b/drivers/xen/xen-pciback/conf_space_capability.c
index 73427d8..e569413 100644
--- a/drivers/xen/xen-pciback/conf_space_capability.c
+++ b/drivers/xen/xen-pciback/conf_space_capability.c
@@ -116,13 +116,12 @@
 {
 	int err;
 	u16 old_value;
-	pci_power_t new_state, old_state;
+	pci_power_t new_state;
 
 	err = pci_read_config_word(dev, offset, &old_value);
 	if (err)
 		goto out;
 
-	old_state = (pci_power_t)(old_value & PCI_PM_CTRL_STATE_MASK);
 	new_state = (pci_power_t)(new_value & PCI_PM_CTRL_STATE_MASK);
 
 	new_value &= PM_OK_BITS;
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 59661db..097410a 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -106,7 +106,8 @@
 	 * is called from "unbind" which takes a device_lock mutex.
 	 */
 	__pci_reset_function_locked(dev);
-	if (pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state))
+	if (dev_data &&
+	    pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state))
 		dev_info(&dev->dev, "Could not reload PCI state\n");
 	else
 		pci_restore_state(dev);
diff --git a/drivers/xen/xen-pciback/pciback_ops.c b/drivers/xen/xen-pciback/pciback_ops.c
index ea4a08b..787966f 100644
--- a/drivers/xen/xen-pciback/pciback_ops.c
+++ b/drivers/xen/xen-pciback/pciback_ops.c
@@ -127,8 +127,6 @@
 		if (pci_is_enabled(dev))
 			pci_disable_device(dev);
 
-		pci_write_config_word(dev, PCI_COMMAND, 0);
-
 		dev->is_busmaster = 0;
 	} else {
 		pci_read_config_word(dev, PCI_COMMAND, &cmd);
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index 581c4e1..833b2d2 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -544,7 +544,7 @@
 		xenbus_switch_state(xdev, XenbusStateClosed);
 		if (xenbus_dev_is_online(xdev))
 			break;
-		/* fall through if not online */
+		/* fall through - if not online */
 	case XenbusStateUnknown:
 		dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 		device_unregister(&xdev->dev);
@@ -697,7 +697,7 @@
 	/* We need to force a call to our callback here in case
 	 * xend already configured us!
 	 */
-	xen_pcibk_be_watch(&pdev->be_watch, NULL, 0);
+	xen_pcibk_be_watch(&pdev->be_watch, NULL, NULL);
 
 out:
 	return err;