root@popat01:/usr/src/asterisk-11.10.2# a.sh core show locks

=======================================================================
=== 11.10.2
=== Currently Held Locks
=======================================================================
===
=== <pending> <lock#> (<file>): <lock type> <line num> <function> <lock name> <lock addr> (times locked)
===
=== Thread ID: 0xb7162b70 (tps_processing_function started at [  471] taskprocessor.c ast_taskprocessor_get())
=== ---> Lock #0 (event.c): RDLOCK 1506 handle_event &(&ast_event_subs[event_types[i]])->lock 0x8227428 (1)
        main/logger.c:1610 ast_bt_get_addresses() (0x813bd3d+19)
        main/lock.c:872 __ast_rwlock_rdlock() (0x8136a68+85)
        main/event.c:1507 handle_event()
        main/taskprocessor.c:332 tps_processing_function()
        main/utils.c:1169 dummy_start()
        :0 start_thread()
        libc.so.6 clone() (0xb7750180+5E)
=== -------------------------------------------------------------------
===
=======================================================================

root@popat01:/usr/src/asterisk-11.10.2# gdb -ex "thread apply all bt" --batch /usr/sbin/asterisk `pidof asterisk` > /tmp/backtrace-threads-lock-device.txt
root@popat01:/usr/src/asterisk-11.10.2# a.sh core show locks

=======================================================================
=== 11.10.2
=== Currently Held Locks
=======================================================================
===
=== <pending> <lock#> (<file>): <lock type> <line num> <function> <lock name> <lock addr> (times locked)
===
=== Thread ID: 0xb7162b70 (tps_processing_function started at [  471] taskprocessor.c ast_taskprocessor_get())
=== ---> Waiting for Lock #0 (event.c): MUTEX 1463 event_update_cache cache 0x9c1e510 (1)
        main/logger.c:1610 ast_bt_get_addresses() (0x813bd3d+19)
        main/lock.c:218 __ast_pthread_mutex_lock() (0x8134f41+85)
        main/astobj2.c:195 __ao2_lock() (0x808ede2+7C)
        main/event.c:1466 event_update_cache()
        main/event.c:1505 handle_event()
        main/taskprocessor.c:332 tps_processing_function()
        main/utils.c:1169 dummy_start()
        :0 start_thread()
        libc.so.6 clone() (0xb7750180+5E)
=== --- ---> Locked Here: event.c line 1463 (event_update_cache)
=== -------------------------------------------------------------------
===
=======================================================================