Ben Greear wrote:
Hello!
I added locking to my ooh323 client and I notice a deadlock:
My code grabs a lock and calls oo to start a call.
I also acquire the same lock when handling the callback for
onStartReceiveChannel. It appears that I deadlock here.
I thought I read somewhere that the commands sent to ooh323c
go onto a queue so that this problem would not occur?
So, after fighting with GDB for some time, I have found the deadlock.
For whatever reason, the second thread (my thread) cannot
get the gCmdMutex lock. Just looking at the nearby code,
I notice none of the error cases unlock the mutex before
returning, so that is instant deadlock waiting to happen :(
If these simple thread locking errors exist, there is no
telling what other more sinister problems exist.
So, I believe I will just remove all the threads from ooh323c and
my program. (I have already cleaned out the rtp stack, so just the main
loop of ooh323c to go.)
Thread 2 (Thread -1208136784 (LWP 27528)):
#0 0xffffe410 in __kernel_vsyscall ()
#1 0x48c86eee in __lll_mutex_lock_wait () from /lib/tls/libpthread.so.0
#2 0x48c83df4 in _L_mutex_lock_29 () from /lib/tls/libpthread.so.0
#3 0x081d9940 in __s_cell_cnt ()
#4 0xb7fd4798 in ?? ()
#5 0x00000106 in ?? ()
#6 0xb7fd4bb0 in ?? ()
#7 0xb7fd4970 in ?? ()
#8 0xb7fd47b8 in ?? ()
#9 0x080944d4 in ooHangCall (callToken=0x81dab94 "\002", reason=3086829936)
at ooStackCmds.c:225
#10 0x080944d4 in ooHangCall (callToken=0x81e669c "ooh323c_2",
reason=OO_REASON_LOCAL_CLEARED) at ooStackCmds.c:225
#11 0x08057e88 in HVoipEndp::doTick (this=0x81e2ec0, input_fds=0xb7fd49f0,
output_fds=0xb7fd4970, exc_fds=0xb7fd48f0, now=1127674726632) at
LFVoipEndp.cc:382
#12 0x0804f628 in LFVoipThread::tick (this=0xbffff420, input_fds=0xb7fd49f0,
output_fds=0xb7fd4970, exc_fds=0xb7fd48f0, now=1127674726632) at
LFVoipHelper.cc:247
#13 0x0804ed98 in LFVoipThread::run (this=0xbffff420) at LFVoipHelper.cc:127
#14 0x0805426f in osEpHandleCommand (dummy=0xbffff420) at lfphone.cc:317
#15 0x48c8198c in start_thread () from /lib/tls/libpthread.so.0
#16 0x48a837da in clone () from /lib/tls/libc.so.6
Thread 1 (Thread -1208029056 (LWP 27526)):
#0 0xffffe410 in __kernel_vsyscall ()
#1 0x48c86eee in __lll_mutex_lock_wait () from /lib/tls/libpthread.so.0
#2 0x48c83e09 in _L_mutex_lock_156 () from /lib/tls/libpthread.so.0
#3 0x081b14a0 in typeinfo name for LogStream ()
#4 0xbfffeef8 in ?? ()
#5 0x081e6900 in ?? ()
#6 0x081d8024 in gProtocolID ()
#7 0x08212344 in ?? ()
#8 0xbfffeef8 in ?? ()
#9 0x08053401 in LFLockable::acquireLock (this=0x81e6900,
---Type <return> to continue, or q <return> to quit---
file_=0x804e168
"U\211\uffff\203\uffff\b\203\uffff\bh\231\uffff\032\b\uffffu\b\uffff\030\uffff\uffff\uffff\203\uffff\020\203\uffff\f\uffffu\b\uffff<\uffff\uffff\uffff\203\uffff\020\213E\b\uffff\uffffU\211\uffffS\203\uffff\004\203\uffff\004\213E\b\213\030\203\uffff\f\uffffu\f\203\uffff\004\uffffu\f\uffff\236\003",
line_=-1073746136) at StackLock.cc:26
#10 0x08053401 in LFLockable::acquireLock (this=0x81e6900,
file_=0x81b18a5 "LFVoipEndp.cc", line_=1174) at StackLock.cc:26
#11 0x0805349d in StackLock (this=0xbfffef40, l=0x81e6900,
file=0x81b18a5 "LFVoipEndp.cc", line=1174) at StackLock.cc:42
#12 0x0805c07d in HVoipEndp::onStartReceiveChannel (this=0x81e2ec0,
call=0x81df338,
pChannel=0x81df688) at LFVoipEndp.cc:1174
#13 0x08053ed5 in osEpStartReceiveChannel (call=0x81df338, pChannel=0x81df688)
at lfphone.cc:178
#14 0x080856e5 in ooBuildFastStartOLC (call=0x81df338, olc=0x8213a10,
epCap=0x81e19b0,
pctxt=0x81da888, dir=1) at ooh245.c:3319
#15 0x0808abf9 in ooH323MakeCall_helper (call=0x81df338) at ooq931.c:2162
#16 0x0808a195 in ooH323CallAdmitted (call=0x81df338) at ooq931.c:1864
#17 0x0808a0c0 in ooH323MakeCall (dest=0x81e1a68 "172.22.22.2:5060",
callToken=0x81e1a88 "ooh323c_2", opts=0x0) at ooq931.c:1832
#18 0x080946e2 in ooProcStackCmds () at ooStackCmds.c:288
#19 0x0807c9e5 in ooMonitorChannels () at oochannels.c:652
#20 0x08053d8b in main (argc=19, argv=0xbffff664) at lfphone.cc:156
#0 0xffffe410 in __kernel_vsyscall ()
(gdb)
Thanks,
Ben
--
Ben Greear <[EMAIL PROTECTED]>
Candela Technologies Inc http://www.candelatech.com
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