ofono_gprs_status_notify is an asynchronous notification that messes
with the 'attached' state of the GPRS atom. This method is normally
prevented from running while an attach is in progress because the
attachment machinery wants to finish up and make it's own determination
of attach state.
When automatic context activation is relevant, as for LTE networks,
the ofono_gprs_cid_activated machinery replaces the usual set_attach
machinery for attaching to the network. The cid_activated variant,
however, does not guard against simulatenous invocations of
ofono_gprs_status_notify. This causes a race whereby status_notify
sets the state to 'attached' before the context is fully constructed
and set to active. If the connection manager sees the 'attached'
state before there are any 'active' contexts, it may decide to
activate a context manually which is not the correct behaviour for
this type of network.
This patch makes the *_cid_activated machinery an 'attaching' state,
introducing the same guards that set_attached has to prevent
ofono_gprs_status_notify from running concurrently.
Otherwise the attached state gets to be set before the actual LTE
automatic context is ready. This triggers a race between connman
and ofono: connman sees status attached before the context is active
so connman will try to activate another context with same apn and will
fail over and over again.
... in pri_deactivate_callback
This prevents attached state from getting stuck at 0 like this:
1. Context deactivation is initiated over D-Bus, ctx->pending is set
2. Attached becomes FALSE, context is still marked as active
3. Attached becomes TRUE, gprs_attached_update sets GPRS_FLAG_ATTACHED_UPDATE
4. Deactivation completes, attached is 0, driver_attached is 1
Futher network status updates don't call gprs_attached_update because
driver_attached is still 1, so attached is staying 0 until we lose the
data registration again which may not happen for quite a long time.
In some cases it is possible that a context is opened after a detach
event has been received, and right before an attach, depending on the
modem. We make sure that those contexts are removed to keep
consistency.
It works by looking for a context with the same APN and tries to use
that. Otherwise it will create it's own.
Then it assigns a gprs context driver and calls it's read_settings if
it exists.
This matches the behavior described by the documentation the signal
value returned by the code. This was causing a headache when using
stricter D-Bus wrappers like dbus-c++.
Jonas Bonn
Christophe Ronco
Dragos Tatulea
Slava Monich
Caiwen Zhang
Alfonso Sanchez-Beato
John Ernberg
Denis Kenzior
Tony Espy
Philip Paeps
Christopher Vogl
Guillaume Zajac
Marcel Holtmann
Lucas De Marchi
Henrique Dante de Almeida
Oleg Zhurakivskyy
Gustavo F. Padovan
Mika Liljeberg