[pulseaudio-discuss] [PATCH] daemon: Stop session-started PA daemon when exiting X session

[Felipe Sateler]

On Tue, Sep 16, 2014 at 11:32 AM, David Henningsson
<david.henningsson at canonical.com> wrote:
>
>
> On 2014-09-16 15:09, Tanu Kaskinen wrote:
>>
>> On Tue, 2014-09-16 at 14:27 +0200, David Henningsson wrote:
>>>
>>>
>>> On 2014-09-15 17:09, Felipe Sateler wrote:
>>>>
>>>> On Mon, Sep 15, 2014 at 5:50 AM, Tanu Kaskinen
>>>> <tanu.kaskinen at linux.intel.com> wrote:
>>>>>
>>>>> On Wed, 2014-09-10 at 09:51 -0300, Felipe Sateler wrote:
>>>>>>
>>>>>> I would think the daemon is per-session, not per-user, given that
>>>>>> (until systemd --user works) we cannot track user stuff across
>>>>>> sessions.
>>>>>
>>>>>
>>>>> We can, module-systemd-login exists for that purpose. It creates a
>>>>> client object for each session that the user has. As long as there are
>>>>> any client objects in PulseAudio, the server won't shut down
>>>>> automatically. When the last client exits, PulseAudio will exit after a
>>>>> delay (20 seconds by default).
>>>>
>>>>
>>>> And what happens if I log in to X, switch to a VT, logout from X and
>>>> login again to X? As I understand the current status, the dbus session
>>>> is tied to the X server, so there should be a new session bus in thi
>>>> case. Does pulseaudio handle this situation correctly? (eg, will
>>>> bluetooth devices work after this?)
>>>
>>>
>>> This is all tricky stuff which we'll need to sort out in some smart way.
>>>
>>> First, as Tanu said, Bluetooth is tied to the system bus. This causes a
>>> problem of its own, given that if we have two different PA instances
>>> running simultaneously as two different users, who should have access to
>>> the bluetooth device(s)? Does anybody know if this handled correctly? [1]
>>
>>
>> My /etc/dbus-1/system.d/bluetooth.conf has this:
>>
>>    <policy at_console="true">
>>      <allow send_destination="org.bluez"/>
>>    </policy>
>>
>> I'm not sure, but I think this means that only the user who has an
>> active session on a seat can access the D-Bus API of BlueZ. If a user is
>> actively using a BT device when switching users, however, I don't think
>> PulseAudio will automatically release the device.
>>
>> On a multi-seat system with multiple simultaneous active users this is
>> probably more broken. Something might happen on this front at some
>> point, since we will have to deal with this in Tizen somehow, as we try
>> to support multi-seat configurations including Bluetooth.
>
>
> Ok, sounds like a plan.
>
>>> Second, for ALSA and the mute issue, I think we need to notify PA
>>> somehow that the system is going down, either for suspend, hibernate or
>>> poweroff. And that needs to complete before ALSA mutes things. This has
>>> nothing to do with X sessions.
>>
>>
>> Does ALSA do the muting also when suspending or hibernating? I haven't
>> noticed such behaviour, but then again, I haven't noticed the poweroff
>> muting either...
>
>
> Felipe, could you elaborate on this? I think I've seen such a mute script,
> but I'm not sure if it was upstream or debian specific, perhaps it's even
> removed these days?

I was never able to reproduce. Unfortunately, the diagnosis is quite
old, so I don't know if something changed that might have fixed the
problem.

The original report is here[1]. This patch comes originally from
another bug report[2], which mentions another two bugs[3][4].

As you can see, all of the reports are fairly old, so I'm not sure if
anything has changed in this regard.

The alsa shutdown script was a debian thing, apparently[5]. However
alsa-utils upstream now includes systemd service files[6]. The two do
not seem to be functionally equivalent, so perhaps the debian specific
sysvinit script was problematic.

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=556971
[2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=594001
[3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=593746
[4] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=593952
[5] http://sources.debian.net/src/alsa-utils/1.0.28-1/debian/init/
[6] http://sources.debian.net/src/alsa-utils/1.0.28-1/alsactl/



-- 

Saludos,
Felipe Sateler