[mythtv-commits] Ticket #11870: Channel scanning deadlock with DVB

[MythTV]

#11870: Channel scanning deadlock with DVB
--------------------------------------------+------------------------
     Reporter:  Rune Petersen <rune@…>      |      Owner:  danielk
         Type:  Bug Report - Hang/Deadlock  |     Status:  new
     Priority:  minor                       |  Milestone:  unknown
    Component:  MythTV - Channel Scanner    |    Version:  0.27-fixes
     Severity:  medium                      |   Keywords:
Ticket locked:  0                           |
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 I get a 100% reproducible deadlock when scanning for DVB channels.

 It always happens on transponder 1070, which may mean this issue is hard
 to trigger.

 Anyway this is clearly a deadlock:
     DVBStreamHandler::RunTS()
         holds MPEGStreamData::_encryption_lock and then tries to take
 ChannelScanSM::lock

     ChannelScanSM::run()
         holds ChannelScanSM::lock and then tries to take
 MPEGStreamData::_encryption_lock

 callstack:
 #0  syscall () at ../ports/sysdeps/unix/sysv/linux/arm/syscall.S:37
 #1  0x75a19624 in ?? () from /usr/lib/arm-linux-gnueabihf/libQtCore.so.4
 #2  0x75a16cfe in QMutex::lockInternal() () from /usr/lib/arm-linux-
 gnueabihf/libQtCore.so.4
 #3  0x769e24e0 in QMutex::lockInline (this=0xe236a8) at
 /usr/include/qt4/QtCore/qmutex.h:198
 #4  0x769e2438 in QMutexLocker::QMutexLocker (this=0x642b993c, m=0xe236a8)
 at /usr/include/qt4/QtCore/qmutex.h:109
 #5  0x76cf9f7c in ChannelScanSM::HandleEncryptionStatus (this=0xe23660,
 pnum=2740, encrypted=true)
     at channelscan/channelscan_sm.cpp:551
 #6  0x76af79be in MPEGStreamData::ProcessEncryptedPacket (this=0xe40890,
 tspacket=...) at mpeg/mpegstreamdata.cpp:2016
 #7  0x76af47a2 in MPEGStreamData::ProcessTSPacket (this=0xe40890,
 tspacket=...) at mpeg/mpegstreamdata.cpp:1046
 #8  0x76af4694 in MPEGStreamData::ProcessData (this=0xe40890,
 buffer=0x6380a008 "G\037\220\220", <incomplete sequence \336>,
     len=102648) at mpeg/mpegstreamdata.cpp:1022
 #9  0x76dcbb4e in DVBStreamHandler::RunTS (this=0xe3d828) at
 recorders/dvbstreamhandler.cpp:266
 #10 0x76dcad84 in DVBStreamHandler::run (this=0xe3d828) at
 recorders/dvbstreamhandler.cpp:118
 #11 0x767ebcde in ?? () from /usr/lib/libmythbase-0.27.so.0
 #12 0x75a1a49a in ?? () from /usr/lib/arm-linux-gnueabihf/libQtCore.so.4
 ---Type <return> to continue, or q <return> to quit---
 #13 0x75a1a49a in ?? () from /usr/lib/arm-linux-gnueabihf/libQtCore.so.4
 Backtrace stopped: previous frame identical to this frame (corrupt stack?)

 Thread 21 (Thread 0x652ba410 (LWP 27669)):
 #0  syscall () at ../ports/sysdeps/unix/sysv/linux/arm/syscall.S:37
 #1  0x75a19624 in ?? () from /usr/lib/arm-linux-gnueabihf/libQtCore.so.4
 ---Type <return> to continue, or q <return> to quit---
 #2  0x75a16dcc in QMutex::lock() () from /usr/lib/arm-linux-
 gnueabihf/libQtCore.so.4
 #3  0x769e24e0 in QMutex::lockInline (this=0xe4094c) at
 /usr/include/qt4/QtCore/qmutex.h:198
 #4  0x769e2438 in QMutexLocker::QMutexLocker (this=0x652b9834, m=0xe4094c)
 at /usr/include/qt4/QtCore/qmutex.h:109
 #5  0x76af71d2 in MPEGStreamData::TestDecryption (this=0xe40890,
 pmt=0x6dca7170) at mpeg/mpegstreamdata.cpp:1885
 #6  0x76cfa450 in ChannelScanSM::TestNextProgramEncryption (this=0xe23660)
 at channelscan/channelscan_sm.cpp:627
 #7  0x76cfb69e in ChannelScanSM::UpdateChannelInfo (this=0xe23660,
 wait_until_complete=false)
     at channelscan/channelscan_sm.cpp:877
 #8  0x76cfede6 in ChannelScanSM::HandleActiveScan (this=0xe23660) at
 channelscan/channelscan_sm.cpp:1584
 #9  0x76cfe8d8 in ChannelScanSM::run (this=0xe23660) at
 channelscan/channelscan_sm.cpp:1482
 #10 0x767ebcba in MThread::run() () from /usr/lib/libmythbase-0.27.so.0
 #11 0x767ebcde in ?? () from /usr/lib/libmythbase-0.27.so.0
 #12 0x75a1a49a in ?? () from /usr/lib/arm-linux-gnueabihf/libQtCore.so.4

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Ticket URL: <http://code.mythtv.org/trac/ticket/11870>
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