From 439d58a55c9bb1c02cd1b9be3775311a4f63561c Mon Sep 17 00:00:00 2001
From: Eric Caruso <ejcaruso@chromium.org>
Date: Tue, 15 Aug 2017 10:52:03 -0700
Subject: [PATCH] mm-broadband-modem-mbim: reprobe on mbim-proxy death

In case mbim-proxy crashes, ModemManager needs to be able to
recognize this and respawn the proxy so we don't lose access
to the modem. Do this by subscribing to the device removal
signal on MbimDevice and reprobing the modem when we lose the
connection to mbim-proxy.

We can't just restart mbim-proxy because the reopened mbim-proxy
will give us a different client ID, and so unsolicitied
notifications will fail and MM gets very confused otherwise.
---
 src/mm-broadband-modem-mbim.c | 66 +++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/mm-broadband-modem-mbim.c b/src/mm-broadband-modem-mbim.c
index 8a722b11..d4f483f0 100644
--- a/src/mm-broadband-modem-mbim.c
+++ b/src/mm-broadband-modem-mbim.c
@@ -90,6 +90,9 @@ struct _MMBroadbandModemMbimPrivate {
     MbimDataClass highest_available_data_class;
 
     MbimSubscriberReadyState last_ready_state;
+
+    /* For notifying when the mbim-proxy connection is dead */
+    gulong mbim_device_removed_id;
 };
 
 /*****************************************************************************/
@@ -1578,11 +1581,63 @@ parent_initialization_started (GTask *task)
         task);
 }
 
+static void
+mbim_device_removed_cb (MbimDevice *device,
+                        MMBroadbandModemMbim *self)
+{
+    /* We have to do a full re-probe here because simply reopening the device
+     * and restarting mbim-proxy will leave us without MBIM notifications. */
+    mm_info ("Connection to mbim-proxy for %s lost, reprobing",
+             mbim_device_get_path_display (device));
+
+    g_signal_handler_disconnect (device,
+                                 self->priv->mbim_device_removed_id);
+    self->priv->mbim_device_removed_id = 0;
+
+    mm_base_modem_set_reprobe (MM_BASE_MODEM (self), TRUE);
+    mm_base_modem_set_valid (MM_BASE_MODEM (self), FALSE);
+}
+
+static void
+track_mbim_device_removed (MMBroadbandModemMbim *self,
+                           MMPortMbim *mbim)
+{
+    MbimDevice *device;
+
+    device = mm_port_mbim_peek_device (mbim);
+    g_assert (device);
+
+    /* Register removal handler so we can handle mbim-proxy crashes */
+    self->priv->mbim_device_removed_id = g_signal_connect (
+        device,
+        MBIM_DEVICE_SIGNAL_REMOVED,
+        G_CALLBACK (mbim_device_removed_cb),
+        self);
+}
+
+static void
+untrack_mbim_device_removed (MMBroadbandModemMbim *self,
+                             MMPortMbim *mbim)
+{
+    MbimDevice *device;
+
+    if (self->priv->mbim_device_removed_id == 0)
+        return;
+
+    device = mm_port_mbim_peek_device (mbim);
+    if (!device)
+        return;
+
+    g_signal_handler_disconnect (device, self->priv->mbim_device_removed_id);
+    self->priv->mbim_device_removed_id = 0;
+}
+
 static void
 mbim_port_open_ready (MMPortMbim *mbim,
                       GAsyncResult *res,
                       GTask *task)
 {
+    MMBroadbandModemMbim *self;
     GError *error = NULL;
 
     if (!mm_port_mbim_open_finish (mbim, res, &error)) {
@@ -1591,7 +1646,10 @@ mbim_port_open_ready (MMPortMbim *mbim,
         return;
     }
 
-    /* Done we are, launch parent's callback */
+    /* Make sure we know if mbim-proxy dies on us, and then do the parent's
+     * initialization */
+    self = MM_BROADBAND_MODEM_MBIM (g_task_get_source_object (task));
+    track_mbim_device_removed (self, mbim);
     parent_initialization_started (task);
 }
 
@@ -1620,7 +1678,9 @@ initialization_started (MMBroadbandModem *self,
     }
 
     if (mm_port_mbim_is_open (ctx->mbim)) {
-        /* Nothing to be done, just launch parent's callback */
+        /* Nothing to be done, just connect to a signal and launch parent's
+         * callback */
+        track_mbim_device_removed (MM_BROADBAND_MODEM_MBIM (self), ctx->mbim);
         parent_initialization_started (task);
         return;
     }
@@ -3193,6 +3253,8 @@ finalize (GObject *object)
         /* Explicitly remove notification handler */
         self->priv->setup_flags = PROCESS_NOTIFICATION_FLAG_NONE;
         common_setup_cleanup_unsolicited_events_sync (self, mm_port_mbim_peek_device (mbim), FALSE);
+        /* Disconnect signal handler for mbim-proxy disappearing, if it exists */
+        untrack_mbim_device_removed (self, mbim);
         /* If we did open the MBIM port during initialization, close it now */
         if (mm_port_mbim_is_open (mbim))
             mm_port_mbim_close (mbim, NULL, NULL);