[PATCH v2 1/1] nbd/server: do not poll within a coroutine context

[Zhu Yangyang]

Coroutines are not supposed to block. Instead, they should yield.

Fixes: f95910f ("nbd: implement TLS support in the protocol negotiation")
Signed-off-by: Zhu Yangyang <zhuyangyang14@huawei.com>
---
 nbd/client.c       |  7 ++++---
 nbd/common.c       | 19 ++++++++++++++++---
 nbd/nbd-internal.h |  6 +++---
 nbd/server.c       | 10 +++++-----
 4 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/nbd/client.c b/nbd/client.c
index 29ffc609a4..1ab91ed205 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -619,18 +619,19 @@ 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);
+        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 3247c1d618..01ca30a5c4 100644
--- a/nbd/common.c
+++ b/nbd/common.c
@@ -47,14 +47,27 @@ int nbd_drop(QIOChannel *ioc, size_t size, Error **errp)
 }
 
 
-void nbd_tls_handshake(QIOTask *task,
-                       void *opaque)
+void nbd_client_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);
+    if (data->loop) {
+        g_main_loop_quit(data->loop);
+    }
+}
+
+
+void nbd_server_tls_handshake(QIOTask *task, void *opaque)
+{
+    struct NBDTLSHandshakeData *data = opaque;
+
+    qio_task_propagate_error(task, &data->error);
+    data->complete = true;
+    if (!qemu_coroutine_entered(data->co)) {
+        aio_co_wake(data->co);
+    }
 }
 
 
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index dfa02f77ee..99cca9382c 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -74,13 +74,13 @@ static inline int nbd_write(QIOChannel *ioc, const void 
*buffer, size_t size,
 
 struct NBDTLSHandshakeData {
     GMainLoop *loop;
+    Coroutine *co;
     bool complete;
     Error *error;
 };
 
-
-void nbd_tls_handshake(QIOTask *task,
-                       void *opaque);
+void nbd_server_tls_handshake(QIOTask *task, void *opaque);
+void nbd_client_tls_handshake(QIOTask *task, void *opaque);
 
 int nbd_drop(QIOChannel *ioc, size_t size, Error **errp);
 
diff --git a/nbd/server.c b/nbd/server.c
index c3484cc1eb..b218512ced 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -777,17 +777,17 @@ 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);
+    while (!data.complete) {
+        qemu_coroutine_yield();
     }
-    g_main_loop_unref(data.loop);
+
     if (data.error) {
         object_unref(OBJECT(tioc));
         error_propagate(errp, data.error);
-- 
2.33.0