deadlock in "pause command handling"

[sss123next]

Attaching to process 7699
[New LWP 7816]
[New LWP 7817]
[New LWP 7818]
[New LWP 8024]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
0x00007f669706cfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0

Thread 5 (Thread 0x7f667919d700 (LWP 8024)):
#0 0x00007f669706cfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00000000004662c3 in PosixCond::wait (mutex=..., this=0xa32cc0) at ./src/thread/PosixCond.hxx:74
#2 AlsaOutput::Play (size=, chunk=, this=0xa32b00) at src/output/plugins/AlsaOutputPlugin.cxx:1259
#3 AudioOutputWrapper::Play (ao=0xa32b50, chunk=, size=) at src/output/plugins/../Wrapper.hxx:81
#4 0x0000000000437ac3 in ao_plugin_play (ao=..., chunk=chunk@entry=0x7f666c07ab18, size=size@entry=4792) at src/output/OutputPlugin.cxx:84
#5 0x0000000000437484 in AudioOutputControl::PlayChunk (this=0xa32e50) at src/output/Thread.cxx:352
#6 AudioOutputControl::InternalPlay (this=0xa32e50) at src/output/Thread.cxx:410
#7 AudioOutputControl::Task (this=0xa32e50) at src/output/Thread.cxx:555
#8 0x0000000000412561 in BindMethodDetail::BindMethodWrapperGenerator2<AudioOutputControl, void (AudioOutputControl::*)(), &AudioOutputControl::Task, void>::Invoke (_instance=) at ./src/util/BindMethod.hxx:147
#9 0x0000000000484641 in BoundMethod<void ()>::operator()() const (this=) at ./src/util/BindMethod.hxx:77
#10 Thread::Run (this=) at src/thread/Thread.cxx:87
#11 Thread::ThreadProc (ctx=) at src/thread/Thread.cxx:112
#12 0x00007f669706737c in start_thread () from /lib64/libpthread.so.0
#13 0x00007f6696dad8ef in clone () from /lib64/libc.so.6

Thread 4 (Thread 0x7f667899c700 (LWP 7818)):
#0 0x00007f669706cfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x000000000043a2a0 in PosixCond::wait (mutex=..., this=0x7f667819ac78) at ./src/thread/PosixCond.hxx:74
#2 DecoderControl::Wait (this=0x7f667819ac50) at src/decoder/DecoderControl.hxx:212
#3 need_chunks (dc=...) at src/decoder/Bridge.cxx:84
#4 0x000000000043a2c9 in LockNeedChunks (dc=...) at src/decoder/Bridge.cxx:93
#5 0x000000000043a8e7 in DecoderBridge::GetChunk (this=this@entry=0x7f667899bc20) at src/decoder/Bridge.cxx:114
#6 0x000000000043adef in DecoderBridge::SubmitData (this=0x7f667899bc20, is=, data=0x7f66680175c0, length=8192, kbit_rate=957) at src/decoder/Bridge.cxx:488
#7 0x000000000045a325 in DecoderClient::SubmitData (kbit_rate=, length=, data=, is=..., this=) at src/decoder/plugins/../Client.hxx:138
#8 FlacDecoder::OnWrite (this=this@entry=0x7f667899b9b0, frame=..., buf=buf@entry=0x7f6668000e08, nbytes=) at src/decoder/plugins/FlacCommon.cxx:153
#9 0x0000000000456bc5 in flac_write_cb (dec=, frame=0x7f66680012e0, buf=0x7f6668000e08, vdata=0x7f667899b9b0) at src/decoder/plugins/FlacDecoderPlugin.cxx:68
#10 0x00007f669edf2664 in read_frame_ () from /usr/lib64/libFLAC.so.8
#11 0x00007f669edef5d0 in FLAC__stream_decoder_process_single () from /usr/lib64/libFLAC.so.8
#12 0x0000000000456d64 in flac_decoder_loop (data=data@entry=0x7f667899b9b0, flac_dec=flac_dec@entry=0x7f6668000b10) at src/decoder/plugins/FlacDecoderPlugin.cxx:199
#13 0x0000000000456e0f in FlacInitAndDecode (data=..., sd=0x7f6668000b10, is_ogg=is_ogg@entry=false) at src/decoder/plugins/FlacDecoderPlugin.cxx:259
#14 0x000000000045716b in flac_decode_internal (client=..., input_stream=..., is_ogg=is_ogg@entry=false) at src/decoder/plugins/FlacDecoderPlugin.cxx:276
#15 0x0000000000457253 in flac_decode (client=..., input_stream=...) at src/decoder/plugins/FlacDecoderPlugin.cxx:282
#16 0x000000000043889a in DecoderPlugin::StreamDecode (is=..., client=..., this=0x496580 <flac_decoder_plugin>) at src/decoder/DecoderPlugin.hxx:127
#17 decoder_stream_decode (plugin=..., bridge=..., input_stream=...) at src/decoder/DecoderThread.cxx:123
#18 0x0000000000438c94 in TryDecoderFile (bridge=..., path_fs=..., path_fs@entry=..., suffix=suffix@entry=0x2113087 "flac", input_stream=..., plugin=...) at src/decoder/DecoderThread.cxx:327
#19 0x0000000000439080 in <lambda(const DecoderPlugin&)>::operator() (plugin=..., __closure=0x7f667899bb30) at src/decoder/DecoderThread.cxx:408
#20 decoder_plugins_try<decoder_run_file(DecoderBridge&, char const*, Path)::<lambda(const DecoderPlugin&)> > (f=...) at src/decoder/DecoderList.hxx:60
#21 decoder_run_file (bridge=..., uri_utf8=uri_utf8@entry=0x2113038 "/home/sss/music/Metal Church/1993 - Hanging In The Balance/09 - End Of The Age.flac", path_fs=...) at src/decoder/DecoderThread.cxx:408
#22 0x0000000000439373 in DecoderUnlockedRunUri (bridge=..., real_uri=real_uri@entry=0x2113038 "/home/sss/music/Metal Church/1993 - Hanging In The Balance/09 - End Of The Age.flac", path_fs=..., path_fs@entry=...)
at src/decoder/DecoderThread.cxx:422
#23 0x0000000000439530 in decoder_run_song (dc=..., song=..., uri=uri@entry=0x2113038 "/home/sss/music/Metal Church/1993 - Hanging In The Balance/09 - End Of The Age.flac", path_fs=...) at src/decoder/DecoderThread.cxx:465
#24 0x0000000000439769 in decoder_run (dc=...) at src/decoder/DecoderThread.cxx:508
#25 0x0000000000439883 in DecoderControl::RunThread (this=0x7f667819ac50) at src/decoder/DecoderThread.cxx:532
#26 0x000000000043996f in BindMethodDetail::BindMethodWrapperGenerator2<DecoderControl, void (DecoderControl::*)(), &DecoderControl::RunThread, void>::Invoke (_instance=) at ./src/util/BindMethod.hxx:147
#27 0x0000000000484641 in BoundMethod<void ()>::operator()() const (this=) at ./src/util/BindMethod.hxx:77
#28 Thread::Run (this=) at src/thread/Thread.cxx:87
#29 Thread::ThreadProc (ctx=) at src/thread/Thread.cxx:112
#30 0x00007f669706737c in start_thread () from /lib64/libpthread.so.0
#31 0x00007f6696dad8ef in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x7f667819b700 (LWP 7817)):
#0 0x00007f669706cfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x0000000000413aee in PosixCond::wait (mutex=..., this=0x6cb668 <audio_output_client_notify+40>) at src/thread/PosixCond.hxx:74
#2 notify::Wait (this=0x6cb640 <audio_output_client_notify>) at src/notify.cxx:28
#3 0x00000000004113dc in MultipleOutputs::WaitAll (this=this@entry=0xa316e0) at src/output/MultipleOutputs.cxx:176
#4 0x00000000004117ab in MultipleOutputs::Pause (this=0xa316e0) at src/output/MultipleOutputs.cxx:373
#5 0x000000000041db79 in Player::ProcessCommand (this=, this=) at src/player/Thread.cxx:689
#6 Player::Run (this=this@entry=0x7f667819ab90) at src/player/Thread.cxx:964
#7 0x000000000041e8c3 in do_play (pc=..., dc=..., buffer=...) at src/player/Thread.cxx:1136
#8 0x000000000041e989 in PlayerControl::RunThread (this=0xa31720) at src/player/Thread.cxx:1160
#9 0x000000000041ebd3 in BindMethodDetail::BindMethodWrapperGenerator2<PlayerControl, void (PlayerControl::*)(), &PlayerControl::RunThread, void>::Invoke (_instance=) at ./src/util/BindMethod.hxx:147
#10 0x0000000000484641 in BoundMethod<void ()>::operator()() const (this=) at ./src/util/BindMethod.hxx:77
#11 Thread::Run (this=) at src/thread/Thread.cxx:87
#12 Thread::ThreadProc (ctx=) at src/thread/Thread.cxx:112
#13 0x00007f669706737c in start_thread () from /lib64/libpthread.so.0
#14 0x00007f6696dad8ef in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f667799a700 (LWP 7816)):
#0 0x00007f6696dadee3 in epoll_wait () from /lib64/libc.so.6
#1 0x00000000004843fb in EPollFD::Wait (timeout=, maxevents=16, events=0xa314b8, this=0xa314b4) at ./src/system/EPollFD.hxx:53
#2 PollGroupEPoll::ReadEvents (timeout_ms=, result=..., this=0xa314b4) at src/event/PollGroupEPoll.hxx:68
#3 EventLoop::Run (this=this@entry=0xa31410) at src/event/Loop.cxx:201
#4 0x0000000000483a94 in EventThread::Run (this=0xa31410) at src/event/Thread.cxx:46
#5 0x000000000041ba67 in BindMethodDetail::BindMethodWrapperGenerator2<EventThread, void (EventThread::*)(), &EventThread::Run, void>::Invoke (_instance=) at ./src/util/BindMethod.hxx:147
#6 0x0000000000484641 in BoundMethod<void ()>::operator()() const (this=) at ./src/util/BindMethod.hxx:77
#7 Thread::Run (this=) at src/thread/Thread.cxx:87
#8 Thread::ThreadProc (ctx=) at src/thread/Thread.cxx:112
#9 0x00007f669706737c in start_thread () from /lib64/libpthread.so.0
#10 0x00007f6696dad8ef in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f669f632f40 (LWP 7699)):
#0 0x00007f669706cfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x000000000041ee11 in PosixCond::wait (mutex=..., this=0xa317c0) at ./src/thread/PosixCond.hxx:74
#2 PlayerControl::ClientWait (this=0xa31720) at src/player/Control.hxx:262
#3 PlayerControl::WaitCommandLocked (this=) at src/player/Control.hxx:310
#4 PlayerControl::SynchronousCommand (cmd=PlayerCommand::PAUSE, this=0xa31720) at src/player/Control.hxx:325
#5 PlayerControl::PauseLocked (this=this@entry=0xa31720) at src/player/Control.cxx:114
#6 0x000000000041eea7 in PlayerControl::LockSetPause (this=this@entry=0xa31720, pause_flag=) at src/player/Control.cxx:137
#7 0x0000000000414ecb in handle_pause (client=..., args=..., r=...) at src/command/PlayerCommands.cxx:100
#8 0x000000000041400e in command_process (client=..., num=num@entry=0, line=line@entry=0x2bb43b0 "pause") at src/command/AllCommands.cxx:418
#9 0x000000000043b97f in client_process_line (client=..., line=, line@entry=0x2bb43b0 "pause") at src/client/ClientProcess.cxx:125
#10 0x0000000000418fe1 in Client::OnSocketInput (this=0x2bb4380, data=0x2bb43b0, length=) at src/client/ClientRead.cxx:47
#11 0x0000000000481fea in BufferedSocket::ResumeInput (this=this@entry=0x2bb4380) at src/event/BufferedSocket.cxx:77
#12 0x000000000048217c in BufferedSocket::OnSocketReady (this=this@entry=0x2bb4380, flags=flags@entry=1) at src/event/BufferedSocket.cxx:117
#13 0x00000000004827d3 in FullyBufferedSocket::OnSocketReady (this=0x2bb4380, flags=1) at src/event/FullyBufferedSocket.cxx:106
#14 0x0000000000481a26 in SocketMonitor::Dispatch (this=0x2bb4380, flags=) at src/event/SocketMonitor.cxx:38
#15 0x0000000000484485 in EventLoop::Run (this=0xa31298) at src/event/Loop.cxx:218
#16 0x0000000000410c05 in mpd_main_after_fork (config=...) at src/Main.cxx:636
#17 0x0000000000410fc3 in mpd_main (argc=, argv=0x7ffcd83289d8) at src/Main.cxx:522
#18 0x000000000041102a in main (argc=, argv=) at src/Main.cxx:425
Detaching from program: /usr/bin/mpd, process 7699

[sss123next]

sorry, fixed in master.

[sss123next]

no, not yet fixed, but master behave a bit differently.
immediately after start something like

#!/bin/sh

while /bin/true; do
	mpc toggle
done

does not cause deadlock

but if pause mpd for some time and try to do it again, it locks.

Thread 5 (Thread 0x7f2475aed700 (LWP 4402)):
#0  0x00007f24959fcfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000046a2e3 in AudioOutputWrapper<AlsaOutput>::Play(AudioOutput*, void const*, unsigned long) ()
#2  0x000000000043b48e in AudioOutputControl::Task() ()
#3  0x000000000048875d in Thread::ThreadProc(void*) ()
#4  0x00007f24959f737c in start_thread () from /lib64/libpthread.so.0
#5  0x00007f249573d8ef in clone () from /lib64/libc.so.6

Thread 4 (Thread 0x7f24752ec700 (LWP 4273)):
#0  0x00007f24959fcfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000043e99d in DecoderBridge::GetChunk() [clone .part.11] ()
#2  0x000000000043f4b0 in DecoderBridge::SubmitData(InputStream*, void const*, unsigned long, unsigned short) ()
#3  0x000000000045e856 in FlacDecoder::OnWrite(FLAC__Frame const&, int const* const*, unsigned long) ()
#4  0x00007f249bbd2664 in read_frame_ () from /usr/lib64/libFLAC.so.8
#5  0x00007f249bbcf5d0 in FLAC__stream_decoder_process_single () from /usr/lib64/libFLAC.so.8
#6  0x000000000045b7aa in flac_decode_internal(DecoderClient&, InputStream&, bool) ()
#7  0x000000000043cdc0 in decoder_stream_decode(DecoderPlugin const&, DecoderBridge&, InputStream&) ()
#8  0x000000000043d4d1 in decoder_run(DecoderControl&) ()
#9  0x000000000043dc1a in DecoderControl::RunThread() ()
#10 0x000000000048875d in Thread::ThreadProc(void*) ()
#11 0x00007f24959f737c in start_thread () from /lib64/libpthread.so.0
#12 0x00007f249573d8ef in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x7f2474aeb700 (LWP 4272)):
#0  0x00007f24959fcfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x0000000000417b93 in notify::Wait() ()
#2  0x0000000000415232 in MultipleOutputs::WaitAll() ()
#3  0x0000000000421fff in Player::Run() ()
#4  0x00000000004227aa in PlayerControl::RunThread() ()
#5  0x000000000048875d in Thread::ThreadProc(void*) ()
#6  0x00007f24959f737c in start_thread () from /lib64/libpthread.so.0
#7  0x00007f249573d8ef in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f24742ea700 (LWP 4271)):
#0  0x00007f249573dee3 in epoll_wait () from /lib64/libc.so.6
#1  0x000000000048830a in EventLoop::Run() ()
#2  0x000000000048875d in Thread::ThreadProc(void*) ()
#3  0x00007f24959f737c in start_thread () from /lib64/libpthread.so.0
#4  0x00007f249573d8ef in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f249c5a3400 (LWP 4267)):
#0  0x00007f24959fcfaf in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1  0x000000000042288b in PlayerControl::PauseLocked() [clone .part.2] ()
#2  0x0000000000422d82 in PlayerControl::LockSetPause(bool) ()
#3  0x0000000000418d7c in handle_pause(Client&, Request, Response&) ()
#4  0x0000000000417f5c in command_process(Client&, unsigned int, char*) ()
#5  0x000000000043ff27 in client_process_line(Client&, char*) ()
#6  0x000000000041d0fb in Client::OnSocketInput(void*, unsigned long) ()
#7  0x0000000000486068 in BufferedSocket::ResumeInput() ()
#8  0x0000000000486201 in BufferedSocket::OnSocketReady(unsigned int) ()
#9  0x0000000000485a61 in SocketMonitor::Dispatch(unsigned int) ()
#10 0x000000000048836b in EventLoop::Run() ()
#11 0x0000000000414800 in mpd_main(int, char**) ()
#12 0x00007f24956781c0 in __libc_start_main () from /lib64/libc.so.6
#13 0x0000000000413dda in _start ()
Detaching from program: /usr/bin/mpd, process 4267

[MaxKellermann]

Can't reproduce, and can't check the source code because the line numbers don't make sense. Bug report is devoid of information, not even a version number.