vfio/ccw: Make vfio_ccw_register_irq_notifier() return a bool

Since vfio_ccw_register_irq_notifier() takes an 'Error **' argument,
best practices suggest to return a bool. See the qapi/error.h Rules
section.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/ccw.c

@@ -379,7 +379,7 @@ read_err:
     css_inject_io_interrupt(sch);
 }
 
-static void vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
+static bool vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
                                            unsigned int irq,
                                            Error **errp)
 {
@@ -405,13 +405,13 @@ static void vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
         break;
     default:
         error_setg(errp, "vfio: Unsupported device irq(%d)", irq);
-        return;
+        return false;
     }
 
     if (vdev->num_irqs < irq + 1) {
         error_setg(errp, "vfio: IRQ %u not available (number of irqs %u)",
                    irq, vdev->num_irqs);
-        return;
+        return false;
     }
 
     argsz = sizeof(*irq_info);
@@ -421,14 +421,14 @@ static void vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
     if (ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO,
               irq_info) < 0 || irq_info->count < 1) {
         error_setg_errno(errp, errno, "vfio: Error getting irq info");
-        return;
+        return false;
     }
 
     if (event_notifier_init(notifier, 0)) {
         error_setg_errno(errp, errno,
                          "vfio: Unable to init event notifier for irq (%d)",
                          irq);
-        return;
+        return false;
     }
 
     fd = event_notifier_get_fd(notifier);
@@ -439,6 +439,8 @@ static void vfio_ccw_register_irq_notifier(VFIOCCWDevice *vcdev,
         qemu_set_fd_handler(fd, NULL, NULL, vcdev);
         event_notifier_cleanup(notifier);
     }
+
+    return true;
 }
 
 static void vfio_ccw_unregister_irq_notifier(VFIOCCWDevice *vcdev,
@@ -602,20 +604,18 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
         goto out_region_err;
     }
 
-    vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_IO_IRQ_INDEX, &err);
-    if (err) {
+    if (!vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_IO_IRQ_INDEX, &err)) {
         goto out_io_notifier_err;
     }
 
     if (vcdev->crw_region) {
-        vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_CRW_IRQ_INDEX, &err);
-        if (err) {
+        if (!vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_CRW_IRQ_INDEX,
+                                            &err)) {
             goto out_irq_notifier_err;
         }
     }
 
-    vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_REQ_IRQ_INDEX, &err);
-    if (err) {
+    if (!vfio_ccw_register_irq_notifier(vcdev, VFIO_CCW_REQ_IRQ_INDEX, &err)) {
         /*
          * Report this error, but do not make it a failing condition.
          * Lack of this IRQ in the host does not prevent normal operation.