diff --git a/aio-posix.c b/aio-posix.c
index 7d66048..2440eb9 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -46,7 +46,6 @@ void aio_set_fd_handler(AioContext *ctx,
                         int fd,
                         IOHandler *io_read,
                         IOHandler *io_write,
-                        AioFlushHandler *io_flush,
                         void *opaque)
 {
     AioHandler *node;
@@ -95,12 +94,10 @@ void aio_set_fd_handler(AioContext *ctx,
 
 void aio_set_event_notifier(AioContext *ctx,
                             EventNotifier *notifier,
-                            EventNotifierHandler *io_read,
-                            AioFlushEventNotifierHandler *io_flush)
+                            EventNotifierHandler *io_read)
 {
     aio_set_fd_handler(ctx, event_notifier_get_fd(notifier),
-                       (IOHandler *)io_read, NULL,
-                       (AioFlushHandler *)io_flush, notifier);
+                       (IOHandler *)io_read, NULL, notifier);
 }
 
 bool aio_pending(AioContext *ctx)
diff --git a/aio-win32.c b/aio-win32.c
index 4309c16..78b2801 100644
--- a/aio-win32.c
+++ b/aio-win32.c
@@ -30,8 +30,7 @@ struct AioHandler {
 
 void aio_set_event_notifier(AioContext *ctx,
                             EventNotifier *e,
-                            EventNotifierHandler *io_notify,
-                            AioFlushEventNotifierHandler *io_flush)
+                            EventNotifierHandler *io_notify)
 {
     AioHandler *node;
 
diff --git a/async.c b/async.c
index 90fe906..fe2c8bf 100644
--- a/async.c
+++ b/async.c
@@ -174,7 +174,7 @@ aio_ctx_finalize(GSource     *source)
     AioContext *ctx = (AioContext *) source;
 
     thread_pool_free(ctx->thread_pool);
-    aio_set_event_notifier(ctx, &ctx->notifier, NULL, NULL);
+    aio_set_event_notifier(ctx, &ctx->notifier, NULL);
     event_notifier_cleanup(&ctx->notifier);
     g_array_free(ctx->pollfds, TRUE);
 }
@@ -214,7 +214,7 @@ AioContext *aio_context_new(void)
     event_notifier_init(&ctx->notifier, false);
     aio_set_event_notifier(ctx, &ctx->notifier, 
                            (EventNotifierHandler *)
-                           event_notifier_test_and_clear, NULL);
+                           event_notifier_test_and_clear);
 
     return ctx;
 }
diff --git a/block/curl.c b/block/curl.c
index 2147076..e88621a 100644
--- a/block/curl.c
+++ b/block/curl.c
@@ -92,17 +92,16 @@ static int curl_sock_cb(CURL *curl, curl_socket_t fd, int action,
     DPRINTF("CURL (AIO): Sock action %d on fd %d\n", action, fd);
     switch (action) {
         case CURL_POLL_IN:
-            qemu_aio_set_fd_handler(fd, curl_multi_do, NULL, NULL, s);
+            qemu_aio_set_fd_handler(fd, curl_multi_do, NULL, s);
             break;
         case CURL_POLL_OUT:
-            qemu_aio_set_fd_handler(fd, NULL, curl_multi_do, NULL, s);
+            qemu_aio_set_fd_handler(fd, NULL, curl_multi_do, s);
             break;
         case CURL_POLL_INOUT:
-            qemu_aio_set_fd_handler(fd, curl_multi_do, curl_multi_do,
-                                    NULL, s);
+            qemu_aio_set_fd_handler(fd, curl_multi_do, curl_multi_do, s);
             break;
         case CURL_POLL_REMOVE:
-            qemu_aio_set_fd_handler(fd, NULL, NULL, NULL, NULL);
+            qemu_aio_set_fd_handler(fd, NULL, NULL, NULL);
             break;
     }
 
diff --git a/block/gluster.c b/block/gluster.c
index 7a69a12..3cff308 100644
--- a/block/gluster.c
+++ b/block/gluster.c
@@ -339,7 +339,7 @@ static int qemu_gluster_open(BlockDriverState *bs,  QDict *options,
     }
     fcntl(s->fds[GLUSTER_FD_READ], F_SETFL, O_NONBLOCK);
     qemu_aio_set_fd_handler(s->fds[GLUSTER_FD_READ],
-        qemu_gluster_aio_event_reader, NULL, NULL, s);
+        qemu_gluster_aio_event_reader, NULL, s);
 
 out:
     qemu_opts_del(opts);
@@ -438,8 +438,7 @@ static void gluster_finish_aiocb(struct glfs_fd *fd, ssize_t ret, void *arg)
         qemu_aio_release(acb);
         close(s->fds[GLUSTER_FD_READ]);
         close(s->fds[GLUSTER_FD_WRITE]);
-        qemu_aio_set_fd_handler(s->fds[GLUSTER_FD_READ], NULL, NULL, NULL,
-            NULL);
+        qemu_aio_set_fd_handler(s->fds[GLUSTER_FD_READ], NULL, NULL, NULL);
         bs->drv = NULL; /* Make the disk inaccessible */
         qemu_mutex_unlock_iothread();
     }
@@ -551,7 +550,7 @@ static void qemu_gluster_close(BlockDriverState *bs)
 
     close(s->fds[GLUSTER_FD_READ]);
     close(s->fds[GLUSTER_FD_WRITE]);
-    qemu_aio_set_fd_handler(s->fds[GLUSTER_FD_READ], NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(s->fds[GLUSTER_FD_READ], NULL, NULL, NULL);
 
     if (s->fd) {
         glfs_close(s->fd);
diff --git a/block/iscsi.c b/block/iscsi.c
index e2041ca..721c7d9 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -160,7 +160,6 @@ iscsi_set_events(IscsiLun *iscsilun)
         qemu_aio_set_fd_handler(iscsi_get_fd(iscsi),
                       iscsi_process_read,
                       (ev & POLLOUT) ? iscsi_process_write : NULL,
-                      NULL,
                       iscsilun);
 
     }
@@ -1176,7 +1175,7 @@ static void iscsi_close(BlockDriverState *bs)
         qemu_del_timer(iscsilun->nop_timer);
         qemu_free_timer(iscsilun->nop_timer);
     }
-    qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL);
     iscsi_destroy_context(iscsi);
     memset(iscsilun, 0, sizeof(IscsiLun));
 }
diff --git a/block/linux-aio.c b/block/linux-aio.c
index d9128f3..53434e2 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -190,8 +190,7 @@ void *laio_init(void)
         goto out_close_efd;
     }
 
-    qemu_aio_set_event_notifier(&s->e, qemu_laio_completion_cb,
-                                NULL);
+    qemu_aio_set_event_notifier(&s->e, qemu_laio_completion_cb);
 
     return s;
 
diff --git a/block/nbd.c b/block/nbd.c
index 80d2b31..f5350fb 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -325,8 +325,7 @@ static int nbd_co_send_request(BDRVNBDState *s, struct nbd_request *request,
 
     qemu_co_mutex_lock(&s->send_mutex);
     s->send_coroutine = qemu_coroutine_self();
-    qemu_aio_set_fd_handler(s->sock, nbd_reply_ready, nbd_restart_write,
-                            NULL, s);
+    qemu_aio_set_fd_handler(s->sock, nbd_reply_ready, nbd_restart_write, s);
     if (qiov) {
         if (!s->is_unix) {
             socket_set_cork(s->sock, 1);
@@ -345,8 +344,7 @@ static int nbd_co_send_request(BDRVNBDState *s, struct nbd_request *request,
     } else {
         rc = nbd_send_request(s->sock, request);
     }
-    qemu_aio_set_fd_handler(s->sock, nbd_reply_ready, NULL,
-                            NULL, s);
+    qemu_aio_set_fd_handler(s->sock, nbd_reply_ready, NULL, s);
     s->send_coroutine = NULL;
     qemu_co_mutex_unlock(&s->send_mutex);
     return rc;
@@ -422,8 +420,7 @@ static int nbd_establish_connection(BlockDriverState *bs)
     /* Now that we're connected, set the socket to be non-blocking and
      * kick the reply mechanism.  */
     qemu_set_nonblock(sock);
-    qemu_aio_set_fd_handler(sock, nbd_reply_ready, NULL,
-                            NULL, s);
+    qemu_aio_set_fd_handler(sock, nbd_reply_ready, NULL, s);
 
     s->sock = sock;
     s->size = size;
@@ -443,7 +440,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
     request.len = 0;
     nbd_send_request(s->sock, &request);
 
-    qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL);
     closesocket(s->sock);
 }
 
diff --git a/block/rbd.c b/block/rbd.c
index 40e5d55..78b8564 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -545,7 +545,7 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags)
     fcntl(s->fds[0], F_SETFL, O_NONBLOCK);
     fcntl(s->fds[1], F_SETFL, O_NONBLOCK);
     qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], qemu_rbd_aio_event_reader,
-                            NULL, NULL, s);
+                            NULL, s);
 
 
     qemu_opts_del(opts);
@@ -569,7 +569,7 @@ static void qemu_rbd_close(BlockDriverState *bs)
 
     close(s->fds[0]);
     close(s->fds[1]);
-    qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(s->fds[RBD_FD_READ], NULL, NULL, NULL);
 
     rbd_close(s->image);
     rados_ioctx_destroy(s->io_ctx);
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 66918c6..be2a876 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -531,14 +531,14 @@ static coroutine_fn void do_co_req(void *opaque)
     unsigned int *rlen = srco->rlen;
 
     co = qemu_coroutine_self();
-    qemu_aio_set_fd_handler(sockfd, NULL, restart_co_req, NULL, co);
+    qemu_aio_set_fd_handler(sockfd, NULL, restart_co_req, co);
 
     ret = send_co_req(sockfd, hdr, data, wlen);
     if (ret < 0) {
         goto out;
     }
 
-    qemu_aio_set_fd_handler(sockfd, restart_co_req, NULL, NULL, co);
+    qemu_aio_set_fd_handler(sockfd, restart_co_req, NULL, co);
 
     ret = qemu_co_recv(sockfd, hdr, sizeof(*hdr));
     if (ret < sizeof(*hdr)) {
@@ -563,7 +563,7 @@ static coroutine_fn void do_co_req(void *opaque)
 out:
     /* there is at most one request for this sockfd, so it is safe to
      * set each handler to NULL. */
-    qemu_aio_set_fd_handler(sockfd, NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(sockfd, NULL, NULL, NULL);
 
     srco->ret = ret;
     srco->finished = true;
@@ -804,7 +804,7 @@ static int get_sheep_fd(BDRVSheepdogState *s)
         return fd;
     }
 
-    qemu_aio_set_fd_handler(fd, co_read_response, NULL, NULL, s);
+    qemu_aio_set_fd_handler(fd, co_read_response, NULL, s);
     return fd;
 }
 
@@ -1054,8 +1054,7 @@ static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
 
     qemu_co_mutex_lock(&s->lock);
     s->co_send = qemu_coroutine_self();
-    qemu_aio_set_fd_handler(s->fd, co_read_response, co_write_request,
-                            NULL, s);
+    qemu_aio_set_fd_handler(s->fd, co_read_response, co_write_request, s);
     socket_set_cork(s->fd, 1);
 
     /* send a header */
@@ -1076,8 +1075,7 @@ static int coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
     }
 
     socket_set_cork(s->fd, 0);
-    qemu_aio_set_fd_handler(s->fd, co_read_response, NULL,
-                            NULL, s);
+    qemu_aio_set_fd_handler(s->fd, co_read_response, NULL, s);
     qemu_co_mutex_unlock(&s->lock);
 
     return 0;
@@ -1335,7 +1333,7 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags)
     g_free(buf);
     return 0;
 out:
-    qemu_aio_set_fd_handler(s->fd, NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(s->fd, NULL, NULL, NULL);
     if (s->fd >= 0) {
         closesocket(s->fd);
     }
@@ -1563,7 +1561,7 @@ static void sd_close(BlockDriverState *bs)
         error_report("%s, %s", sd_strerror(rsp->result), s->name);
     }
 
-    qemu_aio_set_fd_handler(s->fd, NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(s->fd, NULL, NULL, NULL);
     closesocket(s->fd);
     g_free(s->host_spec);
 }
diff --git a/block/ssh.c b/block/ssh.c
index ed525cc..b78253f 100644
--- a/block/ssh.c
+++ b/block/ssh.c
@@ -743,13 +743,13 @@ static coroutine_fn void set_fd_handler(BDRVSSHState *s)
     DPRINTF("s->sock=%d rd_handler=%p wr_handler=%p", s->sock,
             rd_handler, wr_handler);
 
-    qemu_aio_set_fd_handler(s->sock, rd_handler, wr_handler, NULL, co);
+    qemu_aio_set_fd_handler(s->sock, rd_handler, wr_handler, co);
 }
 
 static coroutine_fn void clear_fd_handler(BDRVSSHState *s)
 {
     DPRINTF("s->sock=%d", s->sock);
-    qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL, NULL);
+    qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL);
 }
 
 /* A non-blocking call returned EAGAIN, so yield, ensuring the
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 9e6d32b..bd1b51a 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -473,7 +473,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
         exit(1);
     }
     s->host_notifier = *virtio_queue_get_host_notifier(vq);
-    aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify, NULL);
+    aio_set_event_notifier(s->ctx, &s->host_notifier, handle_notify);
 
     /* Set up ioqueue */
     ioq_init(&s->ioqueue, s->fd, REQ_MAX);
@@ -481,7 +481,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
         ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);
     }
     s->io_notifier = *ioq_get_notifier(&s->ioqueue);
-    aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io, NULL);
+    aio_set_event_notifier(s->ctx, &s->io_notifier, handle_io);
 
     s->started = true;
     trace_virtio_blk_data_plane_start(s);
@@ -513,10 +513,10 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
         qemu_thread_join(&s->thread);
     }
 
-    aio_set_event_notifier(s->ctx, &s->io_notifier, NULL, NULL);
+    aio_set_event_notifier(s->ctx, &s->io_notifier, NULL);
     ioq_cleanup(&s->ioqueue);
 
-    aio_set_event_notifier(s->ctx, &s->host_notifier, NULL, NULL);
+    aio_set_event_notifier(s->ctx, &s->host_notifier, NULL);
     k->set_host_notifier(qbus->parent, 0, false);
 
     aio_context_unref(s->ctx);
diff --git a/include/block/aio.h b/include/block/aio.h
index 1836793..e17066b 100644
--- a/include/block/aio.h
+++ b/include/block/aio.h
@@ -71,9 +71,6 @@ typedef struct AioContext {
     struct ThreadPool *thread_pool;
 } AioContext;
 
-/* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
-typedef int (AioFlushEventNotifierHandler)(EventNotifier *e);
-
 /**
  * aio_context_new: Allocate a new AioContext.
  *
@@ -191,9 +188,6 @@ bool aio_pending(AioContext *ctx);
 bool aio_poll(AioContext *ctx, bool blocking);
 
 #ifdef CONFIG_POSIX
-/* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
-typedef int (AioFlushHandler)(void *opaque);
-
 /* Register a file descriptor and associated callbacks.  Behaves very similarly
  * to qemu_set_fd_handler2.  Unlike qemu_set_fd_handler2, these callbacks will
  * be invoked when using qemu_aio_wait().
@@ -205,7 +199,6 @@ void aio_set_fd_handler(AioContext *ctx,
                         int fd,
                         IOHandler *io_read,
                         IOHandler *io_write,
-                        AioFlushHandler *io_flush,
                         void *opaque);
 #endif
 
@@ -218,8 +211,7 @@ void aio_set_fd_handler(AioContext *ctx,
  */
 void aio_set_event_notifier(AioContext *ctx,
                             EventNotifier *notifier,
-                            EventNotifierHandler *io_read,
-                            AioFlushEventNotifierHandler *io_flush);
+                            EventNotifierHandler *io_read);
 
 /* Return a GSource that lets the main loop poll the file descriptors attached
  * to this AioContext.
@@ -233,14 +225,12 @@ struct ThreadPool *aio_get_thread_pool(AioContext *ctx);
 
 bool qemu_aio_wait(void);
 void qemu_aio_set_event_notifier(EventNotifier *notifier,
-                                 EventNotifierHandler *io_read,
-                                 AioFlushEventNotifierHandler *io_flush);
+                                 EventNotifierHandler *io_read);
 
 #ifdef CONFIG_POSIX
 void qemu_aio_set_fd_handler(int fd,
                              IOHandler *io_read,
                              IOHandler *io_write,
-                             AioFlushHandler *io_flush,
                              void *opaque);
 #endif
 
diff --git a/main-loop.c b/main-loop.c
index cf36645..2581939 100644
--- a/main-loop.c
+++ b/main-loop.c
@@ -488,17 +488,14 @@ bool qemu_aio_wait(void)
 void qemu_aio_set_fd_handler(int fd,
                              IOHandler *io_read,
                              IOHandler *io_write,
-                             AioFlushHandler *io_flush,
                              void *opaque)
 {
-    aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, io_flush,
-                       opaque);
+    aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, opaque);
 }
 #endif
 
 void qemu_aio_set_event_notifier(EventNotifier *notifier,
-                                 EventNotifierHandler *io_read,
-                                 AioFlushEventNotifierHandler *io_flush)
+                                 EventNotifierHandler *io_read)
 {
-    aio_set_event_notifier(qemu_aio_context, notifier, io_read, io_flush);
+    aio_set_event_notifier(qemu_aio_context, notifier, io_read);
 }
diff --git a/tests/test-aio.c b/tests/test-aio.c
index 7b2892a..1ab5637 100644
--- a/tests/test-aio.c
+++ b/tests/test-aio.c
@@ -233,11 +233,11 @@ static void test_set_event_notifier(void)
 {
     EventNotifierTestData data = { .n = 0, .active = 0 };
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 0);
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 0);
     event_notifier_cleanup(&data.e);
@@ -247,7 +247,7 @@ static void test_wait_event_notifier(void)
 {
     EventNotifierTestData data = { .n = 0, .active = 1 };
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 0);
     g_assert_cmpint(data.active, ==, 1);
@@ -261,7 +261,7 @@ static void test_wait_event_notifier(void)
     g_assert_cmpint(data.n, ==, 1);
     g_assert_cmpint(data.active, ==, 0);
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 1);
 
@@ -272,7 +272,7 @@ static void test_flush_event_notifier(void)
 {
     EventNotifierTestData data = { .n = 0, .active = 10, .auto_set = true };
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 0);
     g_assert_cmpint(data.active, ==, 10);
@@ -288,7 +288,7 @@ static void test_flush_event_notifier(void)
     g_assert_cmpint(data.active, ==, 0);
     g_assert(!aio_poll(ctx, false));
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     g_assert(!aio_poll(ctx, false));
     event_notifier_cleanup(&data.e);
 }
@@ -299,7 +299,7 @@ static void test_wait_event_notifier_noflush(void)
     EventNotifierTestData dummy = { .n = 0, .active = 1 };
 
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
 
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 0);
@@ -312,7 +312,7 @@ static void test_wait_event_notifier_noflush(void)
 
     /* An active event notifier forces aio_poll to look at EventNotifiers.  */
     event_notifier_init(&dummy.e, false);
-    aio_set_event_notifier(ctx, &dummy.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &dummy.e, event_ready_cb);
 
     event_notifier_set(&data.e);
     g_assert(aio_poll(ctx, false));
@@ -332,10 +332,10 @@ static void test_wait_event_notifier_noflush(void)
     g_assert_cmpint(dummy.n, ==, 1);
     g_assert_cmpint(dummy.active, ==, 0);
 
-    aio_set_event_notifier(ctx, &dummy.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &dummy.e, NULL);
     event_notifier_cleanup(&dummy.e);
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     g_assert(!aio_poll(ctx, false));
     g_assert_cmpint(data.n, ==, 2);
 
@@ -515,11 +515,11 @@ static void test_source_set_event_notifier(void)
 {
     EventNotifierTestData data = { .n = 0, .active = 0 };
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
     while (g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 0);
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     while (g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 0);
     event_notifier_cleanup(&data.e);
@@ -529,7 +529,7 @@ static void test_source_wait_event_notifier(void)
 {
     EventNotifierTestData data = { .n = 0, .active = 1 };
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
     g_assert(g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 0);
     g_assert_cmpint(data.active, ==, 1);
@@ -543,7 +543,7 @@ static void test_source_wait_event_notifier(void)
     g_assert_cmpint(data.n, ==, 1);
     g_assert_cmpint(data.active, ==, 0);
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     while (g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 1);
 
@@ -554,7 +554,7 @@ static void test_source_flush_event_notifier(void)
 {
     EventNotifierTestData data = { .n = 0, .active = 10, .auto_set = true };
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
     g_assert(g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 0);
     g_assert_cmpint(data.active, ==, 10);
@@ -570,7 +570,7 @@ static void test_source_flush_event_notifier(void)
     g_assert_cmpint(data.active, ==, 0);
     g_assert(!g_main_context_iteration(NULL, false));
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     while (g_main_context_iteration(NULL, false));
     event_notifier_cleanup(&data.e);
 }
@@ -581,7 +581,7 @@ static void test_source_wait_event_notifier_noflush(void)
     EventNotifierTestData dummy = { .n = 0, .active = 1 };
 
     event_notifier_init(&data.e, false);
-    aio_set_event_notifier(ctx, &data.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &data.e, event_ready_cb);
 
     while (g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 0);
@@ -594,7 +594,7 @@ static void test_source_wait_event_notifier_noflush(void)
 
     /* An active event notifier forces aio_poll to look at EventNotifiers.  */
     event_notifier_init(&dummy.e, false);
-    aio_set_event_notifier(ctx, &dummy.e, event_ready_cb, NULL);
+    aio_set_event_notifier(ctx, &dummy.e, event_ready_cb);
 
     event_notifier_set(&data.e);
     g_assert(g_main_context_iteration(NULL, false));
@@ -614,10 +614,10 @@ static void test_source_wait_event_notifier_noflush(void)
     g_assert_cmpint(dummy.n, ==, 1);
     g_assert_cmpint(dummy.active, ==, 0);
 
-    aio_set_event_notifier(ctx, &dummy.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &dummy.e, NULL);
     event_notifier_cleanup(&dummy.e);
 
-    aio_set_event_notifier(ctx, &data.e, NULL, NULL);
+    aio_set_event_notifier(ctx, &data.e, NULL);
     while (g_main_context_iteration(NULL, false));
     g_assert_cmpint(data.n, ==, 2);
 
diff --git a/thread-pool.c b/thread-pool.c
index 096f007..5025567 100644
--- a/thread-pool.c
+++ b/thread-pool.c
@@ -303,8 +303,7 @@ static void thread_pool_init_one(ThreadPool *pool, AioContext *ctx)
     QLIST_INIT(&pool->head);
     QTAILQ_INIT(&pool->request_list);
 
-    aio_set_event_notifier(ctx, &pool->notifier, event_notifier_ready,
-                           NULL);
+    aio_set_event_notifier(ctx, &pool->notifier, event_notifier_ready);
 }
 
 ThreadPool *thread_pool_new(AioContext *ctx)
@@ -338,7 +337,7 @@ void thread_pool_free(ThreadPool *pool)
 
     qemu_mutex_unlock(&pool->lock);
 
-    aio_set_event_notifier(pool->ctx, &pool->notifier, NULL, NULL);
+    aio_set_event_notifier(pool->ctx, &pool->notifier, NULL);
     qemu_sem_destroy(&pool->sem);
     qemu_cond_destroy(&pool->check_cancel);
     qemu_cond_destroy(&pool->worker_stopped);
