Bug#838434: gnome-settings-daemon 100% CPU usage on login

[Andreas Henriksson]

Control: reassign -1 libcups2 2.2.0-1
Control: severity -1 grave
Control: tags -1 + upstream fixed-upstream patch
Cotroll: forwarded -1 https://github.com/apple/cups/issues/4870

Hello Felipe Ortiz.

Thanks for your bug report.

On Wed, Sep 21, 2016 at 02:22:54AM -0300, Felipe Ortiz wrote:
> Package: gnome-settings-daemon
> Version: 3.21.92.1-1
> Severity: normal
> 
> Dear Maintainer,
> 
> After login gnome-settings-daemon use a 100% of my CPU and other wierd
> behavior like multimedia keys malfunction, screen brightness applet
> doesn't work (work fine with function keys) and in gnome-control-center
> can not access to "power" section. Before login CPU usage is normal and
> multimedia keys work as usual.

We've also noticed this problem and the cause is found in the recent
cups update in unstable. To work around the problem you can either
downgrade to libcups{,image}2_2.1.4-4*deb from testing or install
the cups (daemon). Another alternative is to come along for the ride
of fixing this properly which I'll be discussing below.

The problem is that calls to 'cupsGetDests' will end up spinning in
an endless loop if you don't have the cups daemon running/listening.
This can be observed as reported above with gnome-settings-daemon
taking 100% cpu in a normal gnome session or by starting the
gnome-control-center and clicking Printers which will spin forever
waiting for a reply and eating your cpu (both cases cups daemon
not running to trigger the problem).

The issue is already know and fixed upstream. See the above control
information. I've verified the following commit fixes the problems
I'm seeing:
https://github.com/apple/cups/commit/0ca77b3e89dc1f75c91e1a084dba861e378c6c8d

The commit applies cleanly on top of 2.2.0 if you ignore the CHANGES.txt
part. For your convenience I've attached a debdiff.

(Fwiw, the same issue is also discussed in
https://bugzilla.redhat.com/show_bug.cgi?id=1366775 )

Regards,
Andreas Henriksson
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