[regression] Black screen: Mir hangs and then crashes on startup/login due to reading from /dev/random

[Josh Arenson]

cookie_factory attempts to read data from /dev/random at boot, and blocks until it has enough random data or timesout after 30 seconds.

How I can reproduce
1. Run the Unity8 greeter as a mir server
2. Reboot

Expected behavior: Greeter is displayed as mir && USC run happily
Actual behavior: Mir throws an exception after 30 seconds

Work-around:
Before logging in, move the mouse around lots, for at least 20 seconds. And after logging in, while you're looking at a black screen, move the mouse around furiously. This will populate the kernel entropy pool sufficiently to avoid the hang and crash.

[Daniel van Vugt (vanvugt)]

Seems to have come from r2943 (?)

------------------------------------------------------------
revno: 2943 [merge]
author: Brandon Schaefer <email address hidden>, Alan Griffiths <email address hidden>
committer: Tarmac
branch nick: development-branch
timestamp: Thu 2015-09-17 23:46:51 +0000
message:
  server: Added a CookieFactory which generates macs for keyboard/motions events.

  library: CookieFactory creates macs based on timestamp info.

  Approved by Brandon Schaefer, Andreas Pokorny, Alexandros Frantzis, Kevin DuBois, PS Jenkins bot, Alan Griffiths, Chris Halse Rogers.
------------------------------------------------------------

So that means the bug has been around since Mir 0.17 at least.

[PS Jenkins bot (ps-jenkins)]

Fix committed into lp:unity-system-compositor at revision 270, scheduled for release in unity-system-compositor, milestone 0.4.0

[Daniel van Vugt (vanvugt)]

See similar related bug 1541188.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nick Dedekind (nick-dedekind)]

qtmir server plugin will time out waiting for mir thread to start after 10 seconds; should we increase this to match?

[Daniel van Vugt (vanvugt)]

I would say don't change anything right now.

10 seconds is better, and feels less like a system-wide freeze than 30 seconds does. However if we reduce the Mir timeout to 10 seconds right now we'll just get an increased volume of crash reports.

So... don't change anything. Wait until we fix this without needing such delays.

[Daniel van Vugt (vanvugt)]

Dropped importance. Not everyone feels this is a release blocker.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity-system-compositor - 0.4.2+16.04.20160211.2-0ubuntu1

---------------
unity-system-compositor (0.4.2+16.04.20160211.2-0ubuntu1) xenial; urgency=medium

  [ CI Train Bot ]
  * No-change rebuild.

unity-system-compositor (0.4.2+16.04.20160211-0ubuntu1) xenial; urgency=medium

  * Orient the spinner according to the native orientation of the device.
    (LP: #1543495)
  * Implement a stub cookie authority (LP: #1536662)

 -- Alexandros Frantzis <email address hidden> Thu, 11 Feb 2016 12:22:48 +0000

[Mir CI Bot (mir-ci-bot)]

Fix committed into lp:mir at revision None, scheduled for release in mir, milestone 0.21.0

[Mir CI Bot (mir-ci-bot)]

Fix committed into lp:mir at revision None, scheduled for release in mir, milestone 0.22.0

[Launchpad Janitor (janitor)]

This bug was fixed in the package mir - 0.22.1+16.04.20160516.2-0ubuntu2

---------------
mir (0.22.1+16.04.20160516.2-0ubuntu2) yakkety; urgency=medium

  [ Dimitri John Ledkov ]
  * Fix FTBFS error: call of overloaded ‘abs(float)’ is ambiguous, by
    including cmath c++ header.

 -- Łukasz 'sil2100' Zemczak <email address hidden> Thu, 19 May 2016 21:58:43 +0200