touch-packages team mailing list archive

[Robert Carr <racarr@xxxxxxxxxxxxx>]

I propose that this was fixed in r157 onJuly 2nd.

Let's look at how the exception could occur, follow along with grep at
home for fun:

Starting with just the mir tree:

1. The exception can only occur in the InputRegistrar::handle_for_channel (android_input_registrar.cpp).
2. handle_for_channel is only invoked from the InputTargetEnumerator and the InputTargeter.

Let's break things down to find the cause of the exception

0. We can see QtMir does not directly use handle_for_channel
1. The InputTargetEnumerator, this is only used by the InputDispatcher. Of course, in qtmir the InputDispatcher is replaced with the QtEventFeeder, so it can not be Mir's usage of the InputTargetEnumerator triggering the exception. We can see the QtMir tree does not directly use the InputTargetEnumerator either, so we can rule it out as the cause of the exception.
2. The InputTargeter is the remaining culprit and its only used by the shell focus setter.

If we dig in to QtMir though we see
1. The InputTargeter is not used directly
2. The shell focus setter is overriden with a noop

By this logic we have shown that handle_for_channel is never called in
QtMir (and why would it be? It's purely used to translate between
InputDispatcher android types and MirSurfaces to avoid leaking the
android input window interface in to the Mir surface interface...as the
InputDispatcher is eliminated this code should be as well). However
clearly this exception was observed at one point so we must provide an
explanation:

bzr blame focussetter.cpp draws our attention to revision 157 (I suggest
skimming bzr diff 156..157 as the committ message is a little
misleading). We can see prior to r157 QtMir was not overriding the shell
focus setter and making use of the default mir impl, thusly making use
of the InputTargeter. We can also see application_manager.cpp making
direct use of the_focus_controller()->set_focus_to( thus invoking the
input targeter. One feasible explanation for the race is that depending
on the ordering of observer registration the application manager may be
notified surface removal after the input registrar has processed them.

None-the-less I am satisfied that this code path is no longer active and
thus closing the bug as fix released.


** Also affects: qtmir
   Importance: Undecided
       Status: New

** Changed in: mir
       Status: Triaged => Invalid

** Changed in: qtmir
       Status: New => Fix Released

** Changed in: mir/0.6
       Status: Triaged => Invalid

** Changed in: mir (Ubuntu)
       Status: New => Invalid

** Changed in: unity8 (Ubuntu)
       Status: New => Fix Released

** Changed in: qtmir
   Importance: Undecided => High

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to mir in Ubuntu.
https://bugs.launchpad.net/bugs/1292472

Title:
  unity8 crashed with what():  Requesting handle for an unregistered
  channel

Status in Mir:
  Invalid
Status in Mir 0.6 series:
  Invalid
Status in Qt integration with the Mir display server:
  Fix Released
Status in “mir” package in Ubuntu:
  Invalid
Status in “unity8” package in Ubuntu:
  Fix Released

Bug description:
  Every once in a while on current image + proposed (Qt 5.2 is in
  there), unity8 crashes on exit with:

  terminate called after throwing an instance of  'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::logic_error> >'
    what():  Requesting handle for an unregistered channel

  ProblemType: Crash
  DistroRelease: Ubuntu 14.04
  Package: unity8 7.84+14.04.20140307-0ubuntu1 [modified: usr/share/upstart/sessions/unity8.conf]
  Uname: Linux 3.4.0-5-mako armv7l
  ApportVersion: 2.13.3-0ubuntu1
  Architecture: armhf
  CurrentDesktop: Unity
  Date: Fri Mar 14 12:07:08 2014
  ExecutablePath: /usr/bin/unity8
  ExecutableTimestamp: 1394191081
  InstallationDate: Installed on 2014-03-14 (0 days ago)
  InstallationMedia: Ubuntu Trusty Tahr (development branch) - armhf (20140314)
  ProcCmdline: unity8
  ProcCwd: /home/phablet
  Signal: 6
  SourcePackage: unity8
  StacktraceTop:
   __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/arm-linux-gnueabihf/libstdc++.so.6
   ?? () from /usr/lib/arm-linux-gnueabihf/libstdc++.so.6
  Title: unity8 crashed with SIGABRT in __gnu_cxx::__verbose_terminate_handler()
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm autopilot cdrom dialout dip nopasswdlogin plugdev sudo tty video

To manage notifications about this bug go to:
https://bugs.launchpad.net/mir/+bug/1292472/+subscriptions