staging: unisys: uislib: uislib.c: sparse warning of context imbalance

fixed sparse warning : context imbalance in 'destroy_device'
                        unexpected unlock
this patch will generate warning from checkpatch for
lines over 80 character , but since those are user-visible strings
so it was not modified.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Tested-by: Benjamin Romer <benjamin.romer@unisys.com>
Acked-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/uislib/uislib.c

@@ -685,6 +685,7 @@ destroy_device(CONTROLVM_MESSAGE *msg, char *buf)
 	struct bus_info *bus;
 	struct device_info *dev;
 	struct guest_msgs cmd;
+	int retval = CONTROLVM_RESP_SUCCESS;
 
 	busNo = msg->cmd.destroyDevice.busNo;
 	devNo = msg->cmd.destroyDevice.devNo;
@@ -697,18 +698,28 @@ destroy_device(CONTROLVM_MESSAGE *msg, char *buf)
 			if (devNo >= bus->deviceCount) {
 				LOGERR("CONTROLVM_DEVICE_DESTORY Failed: device(%d) >= deviceCount(%d).",
 				       devNo, bus->deviceCount);
-				read_unlock(&BusListLock);
-				return CONTROLVM_RESP_ERROR_DEVICE_INVALID;
-			}
+				retval = CONTROLVM_RESP_ERROR_DEVICE_INVALID;
+			} else {
 				/* make sure this device exists */
 				dev = bus->device[devNo];
 				if (!dev) {
 					LOGERR("CONTROLVM_DEVICE_DESTROY Failed: device %d does not exist.",
 					       devNo);
-				read_unlock(&BusListLock);
-				return CONTROLVM_RESP_ERROR_ALREADY_DONE;
+					retval =
+					     CONTROLVM_RESP_ERROR_ALREADY_DONE;
+				}
+			}
+			break;
+		}
+	}
+
+	if (!bus) {
+		LOGERR("CONTROLVM_DEVICE_DESTROY Failed: bus %d does not exist",
+		       busNo);
+		retval = CONTROLVM_RESP_ERROR_BUS_INVALID;
 	}
 	read_unlock(&BusListLock);
+	if (retval == CONTROLVM_RESP_SUCCESS) {
 		/* the msg is bound for virtpci; send
 		 * guest_msgs struct to callback
 		 */
@@ -716,8 +727,7 @@ destroy_device(CONTROLVM_MESSAGE *msg, char *buf)
 				 UltraVhbaChannelProtocolGuid)) {
 			cmd.msgtype = GUEST_DEL_VHBA;
 			cmd.del_vhba.chanptr = dev->chanptr;
-			} else
-			    if (!uuid_le_cmp(dev->channelTypeGuid,
+		} else if (!uuid_le_cmp(dev->channelTypeGuid,
 					UltraVnicChannelProtocolGuid)) {
 			cmd.msgtype = GUEST_DEL_VNIC;
 			cmd.del_vnic.chanptr = dev->chanptr;
@@ -726,16 +736,15 @@ destroy_device(CONTROLVM_MESSAGE *msg, char *buf)
 			return
 			    CONTROLVM_RESP_ERROR_CHANNEL_TYPE_UNKNOWN;
 		}
-
 		if (!VirtControlChanFunc) {
 			LOGERR("CONTROLVM_DEVICE_DESTORY Failed: virtpci callback not registered.");
 			return
 			    CONTROLVM_RESP_ERROR_VIRTPCI_DRIVER_FAILURE;
 		}
-
 		if (!VirtControlChanFunc(&cmd)) {
 			LOGERR("CONTROLVM_DEVICE_DESTROY Failed: virtpci GUEST_DEL_[VHBA||VNIC] returned error.");
-				return CONTROLVM_RESP_ERROR_VIRTPCI_DRIVER_CALLBACK_ERROR;
+			return
+			    CONTROLVM_RESP_ERROR_VIRTPCI_DRIVER_CALLBACK_ERROR;
 		}
 /* you must disable channel interrupts BEFORE you unmap the channel,
  * because if you unmap first, there may still be some activity going
@@ -753,18 +762,8 @@ destroy_device(CONTROLVM_MESSAGE *msg, char *buf)
 		}
 		kfree(dev);
 		bus->device[devNo] = NULL;
-			break;
-		}
 	}
-
-	if (!bus) {
-		LOGERR("CONTROLVM_DEVICE_DESTROY Failed: bus %d does not exist",
-		       busNo);
-		read_unlock(&BusListLock);
-		return CONTROLVM_RESP_ERROR_BUS_INVALID;
-	}
-
-	return CONTROLVM_RESP_SUCCESS;
+	return retval;
 }
 
 static int