[PATCH v3 2/2] huawei: delay processing of network-initiated disconnection

[Ben Chan]

From: Prathmesh Prabhu <pprabhu at chromium.org>

Huawei MU736 prematurely fires a ^NDISSTAT unsolicited message upon a
network-initiated disconnection. The modem can go into a bad state if a
reconnect attempt happens before the disconnection completes. This patch
works around the issue by delaying the reporting of the disconnection.
---
 plugins/huawei/mm-broadband-bearer-huawei.c | 59 ++++++++++++++++++++++++++++-
 plugins/huawei/mm-broadband-modem-huawei.c  | 15 ++++++--
 2 files changed, 69 insertions(+), 5 deletions(-)

diff --git a/plugins/huawei/mm-broadband-bearer-huawei.c b/plugins/huawei/mm-broadband-bearer-huawei.c
index c9d9001..5f4612c 100644
--- a/plugins/huawei/mm-broadband-bearer-huawei.c
+++ b/plugins/huawei/mm-broadband-bearer-huawei.c
@@ -36,6 +36,8 @@ G_DEFINE_TYPE (MMBroadbandBearerHuawei, mm_broadband_bearer_huawei, MM_TYPE_BROA
 struct _MMBroadbandBearerHuaweiPrivate {
     gpointer connect_pending;
     gpointer disconnect_pending;
+    /* Tag for the post task for network-initiated disconnect */
+    guint network_disconnect_pending_id;
 };
 
 /*****************************************************************************/
@@ -231,6 +233,11 @@ connect_3gpp_context_step (Connect3gppContext *ctx)
         return;
     }
 
+    /* Network-initiated disconnect should not be outstanding at this point,
+     * because it interferes with the connect attempt.
+     */
+    g_assert (ctx->self->priv->network_disconnect_pending_id == 0);
+
     switch (ctx->step) {
     case CONNECT_3GPP_CONTEXT_STEP_FIRST: {
         MMBearerIpFamily ip_family;
@@ -597,6 +604,11 @@ disconnect_3gpp_context_step (Disconnect3gppContext *ctx)
         return;
 
     case DISCONNECT_3GPP_CONTEXT_STEP_LAST:
+        if (ctx->self->priv->network_disconnect_pending_id != 0) {
+            g_source_remove (ctx->self->priv->network_disconnect_pending_id);
+            ctx->self->priv->network_disconnect_pending_id = 0;
+        }
+
         /* Clear context */
         ctx->self->priv->disconnect_pending = NULL;
         /* Set data port as result */
@@ -639,6 +651,18 @@ disconnect_3gpp (MMBroadbandBearer *self,
 
 /*****************************************************************************/
 
+static gboolean
+network_disconnect_3gpp_delayed (MMBroadbandBearerHuawei *self)
+{
+    mm_dbg ("Disconnect bearer '%s' on network request.",
+            mm_bearer_get_path (MM_BEARER (self)));
+
+    self->priv->network_disconnect_pending_id = 0;
+    mm_bearer_report_connection_status (MM_BEARER (self),
+                                        MM_BEARER_CONNECTION_STATUS_DISCONNECTED);
+    return FALSE;
+}
+
 static void
 report_connection_status (MMBearer *bearer,
                           MMBearerConnectionStatus status)
@@ -653,11 +677,28 @@ report_connection_status (MMBearer *bearer,
 
     /* We already use ^NDISSTATQRY? to poll the connection status, so only
      * handle network-initiated disconnection here. */
-    if (status == MM_BEARER_CONNECTION_STATUS_DISCONNECTED) {
-        mm_dbg ("Disconnect bearer '%s'", mm_bearer_get_path (MM_BEARER (self)));
+    switch (status) {
+    case MM_BEARER_CONNECTION_STATUS_DISCONNECTING:
+        /* MM_BEARER_CONNECTION_STATUS_DISCONNECTING is used to indicate that the
+         * reporting of disconnection should be delayed. See MMBroadbandModemHuawei's
+         * bearer_report_connection_status for details. */
+        mm_dbg ("Delay network-initiated disconnection of bearer '%s'",
+                mm_bearer_get_path (MM_BEARER (self)));
+        if (self->priv->network_disconnect_pending_id == 0)
+            self->priv->network_disconnect_pending_id = g_timeout_add_seconds (
+                4,
+                (GSourceFunc) network_disconnect_3gpp_delayed,
+                self);
+        break;
+
+    case MM_BEARER_CONNECTION_STATUS_DISCONNECTED:
         MM_BEARER_CLASS (mm_broadband_bearer_huawei_parent_class)->report_connection_status (
             bearer,
             status);
+        break;
+
+    default:
+        break;
     }
 }
 
@@ -683,6 +724,19 @@ mm_broadband_bearer_huawei_new_finish (GAsyncResult *res,
     return MM_BEARER (bearer);
 }
 
+static void
+dispose (GObject *object)
+{
+    MMBroadbandBearerHuawei *self = MM_BROADBAND_BEARER_HUAWEI (object);
+
+    if (self->priv->network_disconnect_pending_id != 0) {
+        g_source_remove (self->priv->network_disconnect_pending_id);
+        self->priv->network_disconnect_pending_id = 0;
+    }
+
+    G_OBJECT_CLASS (mm_broadband_bearer_huawei_parent_class)->dispose (object);
+}
+
 void
 mm_broadband_bearer_huawei_new (MMBroadbandModemHuawei *modem,
                                 MMBearerProperties *config,
@@ -719,6 +773,7 @@ mm_broadband_bearer_huawei_class_init (MMBroadbandBearerHuaweiClass *klass)
 
     g_type_class_add_private (object_class, sizeof (MMBroadbandBearerHuaweiPrivate));
 
+    object_class->dispose = dispose;
     bearer_class->report_connection_status = report_connection_status;
     broadband_bearer_class->connect_3gpp = connect_3gpp;
     broadband_bearer_class->connect_3gpp_finish = connect_3gpp_finish;
diff --git a/plugins/huawei/mm-broadband-modem-huawei.c b/plugins/huawei/mm-broadband-modem-huawei.c
index f93f5a1..8115440 100644
--- a/plugins/huawei/mm-broadband-modem-huawei.c
+++ b/plugins/huawei/mm-broadband-modem-huawei.c
@@ -1523,13 +1523,22 @@ static void
 bearer_report_connection_status (MMBearer *bearer,
                                  NdisstatResult *ndisstat_result)
 {
+    /* TODO: MMBroadbandBearerHuawei does not currently support IPv6.
+     * When it does, we should check the IP family associated with each bearer. */
     if (ndisstat_result->ipv4_available) {
-        /* TODO: MMBroadbandBearerHuawei does not currently support IPv6.
-         * When it does, we should check the IP family associated with each bearer. */
+        /* A firmware bug in Huawei MU736 causes a ^NDISSTAT unsolicited message
+         * to fire prematurely upon a network-initiated disconnection. The modem
+         * may go into a bad state if we try to reconnect too soon. As a workaround,
+         * we report MM_BEARER_CONNECTION_STATUS_DISCONNECTING instead of
+         * MM_BEARER_CONNECTION_STATUS_DISCONNECTED such that MMBroadbandBearerHuawei's
+         * report_connection_status() will delay the reporting of the connection
+         * status by a few seconds, which is sufficient to ensure that the modem
+         * actually disconnects from the network. Since it is a small delay, we do
+         * this for all Huawei modems. */
         mm_bearer_report_connection_status (bearer,
                                             ndisstat_result->ipv4_connected ?
                                             MM_BEARER_CONNECTION_STATUS_CONNECTED :
-                                            MM_BEARER_CONNECTION_STATUS_DISCONNECTED);
+                                            MM_BEARER_CONNECTION_STATUS_DISCONNECTING);
     }
 }
 
-- 
1.8.4