[PULL,1/2] nbd/server: do not poll within a coroutine context

diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index dfa02f77ee4..91895106a95 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -72,16 +72,6 @@  static inline int nbd_write(QIOChannel *ioc, const void *buffer, size_t size,
     return qio_channel_write_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
 }

-struct NBDTLSHandshakeData {
-    GMainLoop *loop;
-    bool complete;
-    Error *error;
-};
-
-
-void nbd_tls_handshake(QIOTask *task,
-                       void *opaque);
-
 int nbd_drop(QIOChannel *ioc, size_t size, Error **errp);

 #endif
diff --git a/nbd/client.c b/nbd/client.c
index 29ffc609a4b..c89c7504673 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -596,13 +596,31 @@  static int nbd_request_simple_option(QIOChannel *ioc, int opt, bool strict,
     return 1;
 }

+/* Callback to learn when QIO TLS upgrade is complete */
+struct NBDTLSClientHandshakeData {
+    bool complete;
+    Error *error;
+    GMainLoop *loop;
+};
+
+static void nbd_client_tls_handshake(QIOTask *task, void *opaque)
+{
+    struct NBDTLSClientHandshakeData *data = opaque;
+
+    qio_task_propagate_error(task, &data->error);
+    data->complete = true;
+    if (data->loop) {
+        g_main_loop_quit(data->loop);
+    }
+}
+
 static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
                                         QCryptoTLSCreds *tlscreds,
                                         const char *hostname, Error **errp)
 {
     int ret;
     QIOChannelTLS *tioc;
-    struct NBDTLSHandshakeData data = { 0 };
+    struct NBDTLSClientHandshakeData data = { 0 };

     ret = nbd_request_simple_option(ioc, NBD_OPT_STARTTLS, true, errp);
     if (ret <= 0) {
@@ -619,18 +637,20 @@  static QIOChannel *nbd_receive_starttls(QIOChannel *ioc,
         return NULL;
     }
     qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls");
-    data.loop = g_main_loop_new(g_main_context_default(), FALSE);
     trace_nbd_receive_starttls_tls_handshake();
     qio_channel_tls_handshake(tioc,
-                              nbd_tls_handshake,
+                              nbd_client_tls_handshake,
                               &data,
                               NULL,
                               NULL);

     if (!data.complete) {
+        data.loop = g_main_loop_new(g_main_context_default(), FALSE);
         g_main_loop_run(data.loop);
+        assert(data.complete);
+        g_main_loop_unref(data.loop);
     }
-    g_main_loop_unref(data.loop);
+
     if (data.error) {
         error_propagate(errp, data.error);
         object_unref(OBJECT(tioc));
diff --git a/nbd/common.c b/nbd/common.c
index 3247c1d618a..589a748cfe6 100644
--- a/nbd/common.c
+++ b/nbd/common.c
@@ -47,17 +47,6 @@  int nbd_drop(QIOChannel *ioc, size_t size, Error **errp)
 }


-void nbd_tls_handshake(QIOTask *task,
-                       void *opaque)
-{
-    struct NBDTLSHandshakeData *data = opaque;
-
-    qio_task_propagate_error(task, &data->error);
-    data->complete = true;
-    g_main_loop_quit(data->loop);
-}
-
-
 const char *nbd_opt_lookup(uint32_t opt)
 {
     switch (opt) {
diff --git a/nbd/server.c b/nbd/server.c
index c3484cc1ebc..98ae0e16326 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -748,6 +748,23 @@  static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
     return rc;
 }

+/* Callback to learn when QIO TLS upgrade is complete */
+struct NBDTLSServerHandshakeData {
+    bool complete;
+    Error *error;
+    Coroutine *co;
+};
+
+static void nbd_server_tls_handshake(QIOTask *task, void *opaque)
+{
+    struct NBDTLSServerHandshakeData *data = opaque;
+
+    qio_task_propagate_error(task, &data->error);
+    data->complete = true;
+    if (!qemu_coroutine_entered(data->co)) {
+        aio_co_wake(data->co);
+    }
+}

 /* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the
  * new channel for all further (now-encrypted) communication. */
@@ -756,7 +773,7 @@  static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
 {
     QIOChannel *ioc;
     QIOChannelTLS *tioc;
-    struct NBDTLSHandshakeData data = { 0 };
+    struct NBDTLSServerHandshakeData data = { 0 };

     assert(client->opt == NBD_OPT_STARTTLS);

@@ -777,17 +794,18 @@  static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,

     qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-server-tls");
     trace_nbd_negotiate_handle_starttls_handshake();
-    data.loop = g_main_loop_new(g_main_context_default(), FALSE);
+    data.co = qemu_coroutine_self();
     qio_channel_tls_handshake(tioc,
-                              nbd_tls_handshake,
+                              nbd_server_tls_handshake,
                               &data,
                               NULL,
                               NULL);

     if (!data.complete) {
-        g_main_loop_run(data.loop);
+        qemu_coroutine_yield();
+        assert(data.complete);
     }
-    g_main_loop_unref(data.loop);
+
     if (data.error) {
         object_unref(OBJECT(tioc));
         error_propagate(errp, data.error);