[PULL 23/34] nbd/client-connection: shutdown connection on release

[Eric Blake]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Now, when a thread can do negotiation and retry, it may run relatively
long. We need a mechanism to stop it, when the user is not interested
in a result any more. So, on nbd_client_connection_release() let's
shutdown the socket, and do not retry connection if thread is detached.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210610100802.5888-22-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 nbd/client-connection.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/nbd/client-connection.c b/nbd/client-connection.c
index 032b38ed3e9b..883f9cf158cb 100644
--- a/nbd/client-connection.c
+++ b/nbd/client-connection.c
@@ -168,9 +168,13 @@ static void *connect_thread_func(void *opaque)
     uint64_t timeout = 1;
     uint64_t max_timeout = 16;

-    while (true) {
+    qemu_mutex_lock(&conn->mutex);
+    while (!conn->detached) {
+        assert(!conn->sioc);
         conn->sioc = qio_channel_socket_new();

+        qemu_mutex_unlock(&conn->mutex);
+
         error_free(conn->err);
         conn->err = NULL;
         conn->updated_info = conn->initial_info;
@@ -188,14 +192,20 @@ static void *connect_thread_func(void *opaque)
         conn->updated_info.x_dirty_bitmap = NULL;
         conn->updated_info.name = NULL;

+        qemu_mutex_lock(&conn->mutex);
+
         if (ret < 0) {
             object_unref(OBJECT(conn->sioc));
             conn->sioc = NULL;
-            if (conn->do_retry) {
+            if (conn->do_retry && !conn->detached) {
+                qemu_mutex_unlock(&conn->mutex);
+
                 sleep(timeout);
                 if (timeout < max_timeout) {
                     timeout *= 2;
                 }
+
+                qemu_mutex_lock(&conn->mutex);
                 continue;
             }
         }
@@ -203,7 +213,7 @@ static void *connect_thread_func(void *opaque)
         break;
     }

-    qemu_mutex_lock(&conn->mutex);
+    /* mutex is locked */

     assert(conn->running);
     conn->running = false;
@@ -237,6 +247,10 @@ void nbd_client_connection_release(NBDClientConnection 
*conn)
         } else {
             do_free = true;
         }
+        if (conn->sioc) {
+            qio_channel_shutdown(QIO_CHANNEL(conn->sioc),
+                                 QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+        }
     }

     if (do_free) {
-- 
2.31.1