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-rw-r--r--chardev/char-socket.c90
1 files changed, 86 insertions, 4 deletions
diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 86c1f50..4fcdd8a 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -80,6 +80,8 @@ typedef struct {
GSource *reconnect_timer;
int64_t reconnect_time;
bool connect_err_reported;
+
+ QIOTask *connect_task;
} SocketChardev;
#define SOCKET_CHARDEV(obj) \
@@ -118,6 +120,7 @@ static void qemu_chr_socket_restart_timer(Chardev *chr)
char *name;
assert(s->state == TCP_CHARDEV_STATE_DISCONNECTED);
+ assert(!s->reconnect_timer);
name = g_strdup_printf("chardev-socket-reconnect-%s", chr->label);
s->reconnect_timer = qemu_chr_timeout_add_ms(chr,
s->reconnect_time * 1000,
@@ -965,7 +968,56 @@ static int tcp_chr_wait_connected(Chardev *chr, Error **errp)
}
}
- while (!s->ioc) {
+ tcp_chr_reconn_timer_cancel(s);
+
+ /*
+ * We expect states to be as follows:
+ *
+ * - server
+ * - wait -> CONNECTED
+ * - nowait -> DISCONNECTED
+ * - client
+ * - reconnect == 0 -> CONNECTED
+ * - reconnect != 0 -> CONNECTING
+ *
+ */
+ if (s->state == TCP_CHARDEV_STATE_CONNECTING) {
+ if (!s->connect_task) {
+ error_setg(errp,
+ "Unexpected 'connecting' state without connect task "
+ "while waiting for connection completion");
+ return -1;
+ }
+ /*
+ * tcp_chr_wait_connected should only ever be run from the
+ * main loop thread associated with chr->gcontext, otherwise
+ * qio_task_wait_thread has a dangerous race condition with
+ * free'ing of the s->connect_task object.
+ *
+ * Acquiring the main context doesn't 100% prove we're in
+ * the main loop thread, but it does at least guarantee
+ * that the main loop won't be executed by another thread
+ * avoiding the race condition with the task idle callback.
+ */
+ g_main_context_acquire(chr->gcontext);
+ qio_task_wait_thread(s->connect_task);
+ g_main_context_release(chr->gcontext);
+
+ /*
+ * The completion callback (qemu_chr_socket_connected) for
+ * s->connect_task should have set this to NULL by the time
+ * qio_task_wait_thread has returned.
+ */
+ assert(!s->connect_task);
+
+ /*
+ * NB we are *not* guaranteed to have "s->state == ..CONNECTED"
+ * at this point as this first connect may be failed, so
+ * allow the next loop to run regardless.
+ */
+ }
+
+ while (s->state != TCP_CHARDEV_STATE_CONNECTED) {
if (s->is_listen) {
tcp_chr_accept_server_sync(chr);
} else {
@@ -1014,6 +1066,8 @@ static void qemu_chr_socket_connected(QIOTask *task, void *opaque)
SocketChardev *s = SOCKET_CHARDEV(chr);
Error *err = NULL;
+ s->connect_task = NULL;
+
if (qio_task_propagate_error(task, &err)) {
tcp_chr_change_state(s, TCP_CHARDEV_STATE_DISCONNECTED);
check_report_connect_error(chr, err);
@@ -1028,6 +1082,20 @@ cleanup:
object_unref(OBJECT(sioc));
}
+
+static void tcp_chr_connect_client_task(QIOTask *task,
+ gpointer opaque)
+{
+ QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(qio_task_get_source(task));
+ SocketAddress *addr = opaque;
+ Error *err = NULL;
+
+ qio_channel_socket_connect_sync(ioc, addr, &err);
+
+ qio_task_set_error(task, err);
+}
+
+
static void tcp_chr_connect_client_async(Chardev *chr)
{
SocketChardev *s = SOCKET_CHARDEV(chr);
@@ -1036,9 +1104,23 @@ static void tcp_chr_connect_client_async(Chardev *chr)
tcp_chr_change_state(s, TCP_CHARDEV_STATE_CONNECTING);
sioc = qio_channel_socket_new();
tcp_chr_set_client_ioc_name(chr, sioc);
- qio_channel_socket_connect_async(sioc, s->addr,
- qemu_chr_socket_connected,
- chr, NULL, chr->gcontext);
+ /*
+ * Normally code would use the qio_channel_socket_connect_async
+ * method which uses a QIOTask + qio_task_set_error internally
+ * to avoid blocking. The tcp_chr_wait_connected method, however,
+ * needs a way to synchronize with completion of the background
+ * connect task which can't be done with the QIOChannelSocket
+ * async APIs. Thus we must use QIOTask directly to implement
+ * the non-blocking concept locally.
+ */
+ s->connect_task = qio_task_new(OBJECT(sioc),
+ qemu_chr_socket_connected,
+ chr, NULL);
+ qio_task_run_in_thread(s->connect_task,
+ tcp_chr_connect_client_task,
+ s->addr,
+ NULL,
+ chr->gcontext);
}
static gboolean socket_reconnect_timeout(gpointer opaque)