diff --git a/dma-helpers.c b/dma-helpers.c
index 2d7e02d35e..d3871dc61e 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -90,6 +90,7 @@ static void reschedule_dma(void *opaque)
 {
     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
 
+    assert(!dbs->acb && dbs->bh);
     qemu_bh_delete(dbs->bh);
     dbs->bh = NULL;
     dma_blk_cb(dbs, 0);
@@ -111,15 +112,12 @@ static void dma_complete(DMAAIOCB *dbs, int ret)
 {
     trace_dma_complete(dbs, ret, dbs->common.cb);
 
+    assert(!dbs->acb && !dbs->bh);
     dma_blk_unmap(dbs);
     if (dbs->common.cb) {
         dbs->common.cb(dbs->common.opaque, ret);
     }
     qemu_iovec_destroy(&dbs->iov);
-    if (dbs->bh) {
-        qemu_bh_delete(dbs->bh);
-        dbs->bh = NULL;
-    }
     qemu_aio_unref(dbs);
 }
 
@@ -179,14 +177,21 @@ static void dma_aio_cancel(BlockAIOCB *acb)
 
     trace_dma_aio_cancel(dbs);
 
+    assert(!(dbs->acb && dbs->bh));
     if (dbs->acb) {
+        /* This will invoke dma_blk_cb.  */
         blk_aio_cancel_async(dbs->acb);
+        return;
     }
+
     if (dbs->bh) {
         cpu_unregister_map_client(dbs->bh);
         qemu_bh_delete(dbs->bh);
         dbs->bh = NULL;
     }
+    if (dbs->common.cb) {
+        dbs->common.cb(dbs->common.opaque, -ECANCELED);
+    }
 }
 
 static AioContext *dma_get_aio_context(BlockAIOCB *acb)