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<base href="https://bugs.freedesktop.org/" />
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<th>Priority</th>
<td>medium
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - pa_mainloop_quit() can't make pa_mainloop_run exit"
href="https://bugs.freedesktop.org/show_bug.cgi?id=56735">56735</a>
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<th>CC</th>
<td>lennart@poettering.net
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<th>Assignee</th>
<td>pulseaudio-bugs@lists.freedesktop.org
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<th>Summary</th>
<td>pa_mainloop_quit() can't make pa_mainloop_run exit
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<th>QA Contact</th>
<td>pulseaudio-bugs@lists.freedesktop.org
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<th>Severity</th>
<td>critical
</td>
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<th>Classification</th>
<td>Unclassified
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<th>OS</th>
<td>Linux (All)
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<th>Reporter</th>
<td>changyp6@gmail.com
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<th>Hardware</th>
<td>Other
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Version</th>
<td>unspecified
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<th>Component</th>
<td>clients
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<th>Product</th>
<td>PulseAudio
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<p>
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<pre>I wrote a recording program using pulseaudio's API. version 2.1
I found that pa_mainloop_quit can't make pa_mainloop_run exit.
I did a little digging on this problem, and I think I have found this bug.
In pa_mainloop_quit, pa_mainloop_wakeup is called to make pa_mainloop_poll
unblocked from select.
However, In pa_mainloop_wakeup, only if m->state == STATE_POLLING,
this wake up signal is sent to pa_mainloop_poll.
In pa_mainloop_poll, checking if m->quit is set and setting m->state to
STATE_POLLING is not protected.
So, in this case, in multi-thread program, it is possible that
Mainloop-thread: pa_mainloop_poll checked m->quit is set to 0, m->state !=
STATE_POLLING
Controlling-thread: pa_mainloop_quit->pa_mainloop_wakeup checked m->state !=
STATE_POLLING, failed sending wake up signal
Mainloop-thread: pa_mainloop_polling set m->state = STATE_POLLING and go on
calling pa_poll, and everything stops here.
There is on solution: pa_mainloop_wakeup doesn't check if m->state ==
STATE_POLLING, it just send wake up signal, so pa_mainloop_polling will receive
this signal
Or protect the m->quit checking and m->state setting section in
pa_mainloop_poll
and protect pa_mainloop_quit with on mutex, make these two API won't run in
mixed way.
To work around this bug, I have to call pa_mainloop_quit multiple times to make
sure pa_mainloop_run is quit.
Hope this bug can be fixed sooner.</pre>
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