virtio-blk: extract cleanup_iothread_vq_mapping() function

This is the cleanup function that must be called after
apply_iothread_vq_mapping() succeeds. virtio-scsi will need this
function too, so extract it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-9-stefanha@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/block/virtio-blk.c

@@ -1495,6 +1495,9 @@ validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
  * Fill in the AioContext for each virtqueue in the @vq_aio_context array given
  * the iothread-vq-mapping parameter in @iothread_vq_mapping_list.
  *
+ * cleanup_iothread_vq_mapping() must be called to free IOThread object
+ * references after this function returns success.
+ *
  * Returns: %true on success, %false on failure.
  **/
 static bool apply_iothread_vq_mapping(
@@ -1545,6 +1548,23 @@ static bool apply_iothread_vq_mapping(
     return true;
 }
 
+/**
+ * cleanup_iothread_vq_mapping:
+ * @list: The mapping of virtqueues to IOThreads.
+ *
+ * Release IOThread object references that were acquired by
+ * apply_iothread_vq_mapping().
+ */
+static void cleanup_iothread_vq_mapping(IOThreadVirtQueueMappingList *list)
+{
+    IOThreadVirtQueueMappingList *node;
+
+    for (node = list; node; node = node->next) {
+        IOThread *iothread = iothread_by_id(node->value->iothread);
+        object_unref(OBJECT(iothread));
+    }
+}
+
 /* Context: BQL held */
 static bool virtio_blk_vq_aio_context_init(VirtIOBlock *s, Error **errp)
 {
@@ -1611,12 +1631,7 @@ static void virtio_blk_vq_aio_context_cleanup(VirtIOBlock *s)
     assert(!s->ioeventfd_started);
 
     if (conf->iothread_vq_mapping_list) {
-        IOThreadVirtQueueMappingList *node;
-
-        for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
-            IOThread *iothread = iothread_by_id(node->value->iothread);
-            object_unref(OBJECT(iothread));
-        }
+        cleanup_iothread_vq_mapping(conf->iothread_vq_mapping_list);
     }
 
     if (conf->iothread) {