[PATCH RFC 07/26] migration/postcopy: pass PostcopyPChannelConnectData when connecting sending preempt socket

["Maciej S. Szmigiero" <mail@maciej.szmigiero.name>]

From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

This will allow passing additional parameters there in the future.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 migration/postcopy-ram.c | 68 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 61 insertions(+), 7 deletions(-)

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index e314e1023dc1..94fe872d8251 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -1617,14 +1617,62 @@ void postcopy_preempt_new_channel(MigrationIncomingState *mis, QEMUFile *file)
     trace_postcopy_preempt_new_channel();
 }
 
+typedef struct {
+    unsigned int ref;
+    MigrationState *s;
+} PostcopyPChannelConnectData;
+
+static PostcopyPChannelConnectData *pcopy_preempt_connect_data_new(MigrationState *s)
+{
+    PostcopyPChannelConnectData *data;
+
+    data = g_malloc0(sizeof(*data));
+    data->ref = 1;
+    data->s = s;
+
+    return data;
+}
+
+static void pcopy_preempt_connect_data_free(PostcopyPChannelConnectData *data)
+{
+    g_free(data);
+}
+
+static PostcopyPChannelConnectData *
+pcopy_preempt_connect_data_ref(PostcopyPChannelConnectData *data)
+{
+    unsigned int ref_old;
+
+    ref_old = qatomic_fetch_inc(&data->ref);
+    assert(ref_old < UINT_MAX);
+
+    return data;
+}
+
+static void pcopy_preempt_connect_data_unref(gpointer opaque)
+{
+    PostcopyPChannelConnectData *data = opaque;
+    unsigned int ref_old;
+
+    ref_old = qatomic_fetch_dec(&data->ref);
+    assert(ref_old > 0);
+    if (ref_old == 1) {
+        pcopy_preempt_connect_data_free(data);
+    }
+}
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(PostcopyPChannelConnectData, pcopy_preempt_connect_data_unref)
+
 /*
  * Setup the postcopy preempt channel with the IOC.  If ERROR is specified,
  * setup the error instead.  This helper will free the ERROR if specified.
  */
 static void
-postcopy_preempt_send_channel_done(MigrationState *s,
+postcopy_preempt_send_channel_done(PostcopyPChannelConnectData *data,
                                    QIOChannel *ioc, Error *local_err)
 {
+    MigrationState *s = data->s;
+
     if (local_err) {
         migrate_set_error(s, local_err);
         error_free(local_err);
@@ -1645,18 +1693,19 @@ static void
 postcopy_preempt_tls_handshake(QIOTask *task, gpointer opaque)
 {
     g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
-    MigrationState *s = opaque;
+    PostcopyPChannelConnectData *data = opaque;
     Error *local_err = NULL;
 
     qio_task_propagate_error(task, &local_err);
-    postcopy_preempt_send_channel_done(s, ioc, local_err);
+    postcopy_preempt_send_channel_done(data, ioc, local_err);
 }
 
 static void
 postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
 {
     g_autoptr(QIOChannel) ioc = QIO_CHANNEL(qio_task_get_source(task));
-    MigrationState *s = opaque;
+    PostcopyPChannelConnectData *data = opaque;
+    MigrationState *s = data->s;
     QIOChannelTLS *tioc;
     Error *local_err = NULL;
 
@@ -1672,14 +1721,15 @@ postcopy_preempt_send_channel_new(QIOTask *task, gpointer opaque)
         trace_postcopy_preempt_tls_handshake();
         qio_channel_set_name(QIO_CHANNEL(tioc), "migration-tls-preempt");
         qio_channel_tls_handshake(tioc, postcopy_preempt_tls_handshake,
-                                  s, NULL, NULL);
+                                  pcopy_preempt_connect_data_ref(data),
+                                  pcopy_preempt_connect_data_unref, NULL);
         /* Setup the channel until TLS handshake finished */
         return;
     }
 
 out:
     /* This handles both good and error cases */
-    postcopy_preempt_send_channel_done(s, ioc, local_err);
+    postcopy_preempt_send_channel_done(data, ioc, local_err);
 }
 
 /*
@@ -1714,8 +1764,12 @@ int postcopy_preempt_establish_channel(MigrationState *s)
 
 void postcopy_preempt_setup(MigrationState *s)
 {
+    PostcopyPChannelConnectData *data;
+
+    data = pcopy_preempt_connect_data_new(s);
     /* Kick an async task to connect */
-    socket_send_channel_create(postcopy_preempt_send_channel_new, s, NULL);
+    socket_send_channel_create(postcopy_preempt_send_channel_new,
+                               data, pcopy_preempt_connect_data_unref);
 }
 
 static void postcopy_pause_ram_fast_load(MigrationIncomingState *mis)