[PATCH] ppp-manager: fix pppd not exiting correctly on modem hangup

[Frederic Danis <frederic danis external sigfox com>]

When unplugging an USB 3G modem device, pppd does not exit correctly and
we have the following traces:

Sep 10 07:58:24.616465 ModemManager[1158]: <info>  (tty/ttyUSB0): released by device 
'/sys/devices/pci0000:00/0000:00:1c.0/0000:01:00.0/usb4/4-1'
Sep 10 07:58:24.620314 pppd[2292]: Modem hangup
Sep 10 07:58:24.621368 ModemManager[1158]: <info>  (tty/ttyUSB1): released by device 
'/sys/devices/pci0000:00/0000:00:1c.0/0000:01:00.0/usb4/4-1'
Sep 10 07:58:24.621835 ModemManager[1158]: <warn>  (ttyUSB1): could not re-acquire serial port lock: (5) 
Input/output error
Sep 10 07:58:24.621358 NetworkManager[1871]: <debug> ppp-manager: set-ifindex 4
Sep 10 07:58:24.621369 NetworkManager[1871]: <warn>  ppp-manager: can't change the ifindex from 4 to 4
Sep 10 07:58:24.623982 NetworkManager[1871]: <info>  device (ttyUSB0): state change: activated -> unmanaged 
(reason 'removed', sys-iface-state: 'removed')
Sep 10 07:58:24.624411 NetworkManager[1871]: <debug> kill child process 'pppd' (2292): wait for process to 
terminate after sending SIGTERM (15) (send SIGKILL in 1500 milliseconds)...
Sep 10 07:58:24.624440 NetworkManager[1871]: <debug> modem-broadband[ttyUSB0]: notifying ModemManager about 
the modem disconnection
Sep 10 07:58:24.626591 NetworkManager[1871]: <debug> modem-broadband[ttyUSB0]: notifying ModemManager about 
the modem disconnection
Sep 10 07:58:24.681016 NetworkManager[1871]: <warn>  modem-broadband[ttyUSB0]: failed to disconnect modem: 
GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface 
'org.freedesktop.ModemManager1.Modem.Simple' on object at path /org/freedesktop/ModemManager1/Modem/0
Sep 10 07:58:26.126817 NetworkManager[1871]: <debug> kill child process 'pppd' (2292): process not terminated 
after 1502368 usec. Sending SIGKILL signal
Sep 10 07:58:26.128121 NetworkManager[1871]: <info>  device (ppp0): state change: disconnected -> unmanaged 
(reason 'unmanaged', sys-iface-state: 'removed')
Sep 10 07:58:26.135571 NetworkManager[1871]: <debug> kill child process 'pppd' (2292): terminated by signal 9 
(1511158 usec elapsed)

This is due to nm-ppp-plugin waiting on SetIfIndex call until timeout,
which is longer than termination process timeout.

Calling g_dbus_method_invocation_return_value() on error fixes this.
---
 src/ppp/nm-ppp-manager.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/ppp/nm-ppp-manager.c b/src/ppp/nm-ppp-manager.c
index 5e893c8..079de9f 100644
--- a/src/ppp/nm-ppp-manager.c
+++ b/src/ppp/nm-ppp-manager.c
@@ -442,7 +442,7 @@ impl_ppp_manager_set_ifindex (NMDBusObject *obj,
 
        if (priv->ifindex >= 0) {
                _LOGW ("can't change the ifindex from %d to %d", priv->ifindex, (int) ifindex);
-               return;
+               goto out;
        }
 
        if (ifindex > 0) {
@@ -463,6 +463,8 @@ impl_ppp_manager_set_ifindex (NMDBusObject *obj,
        obj_keep_alive = nmp_object_ref (NMP_OBJECT_UP_CAST (plink));
 
        g_signal_emit (self, signals[IFINDEX_SET], 0, ifindex, plink->name);
+
+out:
        g_dbus_method_invocation_return_value (invocation, NULL);
 }
 
-- 
2.7.4