[lldb-dev] FreeBSD thread abort from pthread_cond_timedwait call within signal handler

[Ed Maste]

I can now launch my inferior process on FreeBSD, but fail to get a
notification at process termination and then lldb waits indefinitely.
Upon hitting ^C I get an abort from an assertion in the thread library
"Fatal error 'thread was already on queue.'"  It looks to come from
calling non-async-signal-safe pthread_cond_timedwait from the signal
handler:

#1  0x0000000805ef756c in abort () at
/home/emaste/src/9/lib/libc/stdlib/abort.c:65
#2  0x0000000800850d2c in _thread_exit (fname=<value optimized out>,
lineno=<value optimized out>, msg=<value optimized out>)
    at /home/emaste/src/9/lib/libthr/thread/thr_exit.c:182
#3  0x000000080084fc1d in cond_wait_common (cond=<value optimized
out>, mutex=<value optimized out>, abstime=<value optimized out>,
    cancel=<value optimized out>) at
/home/emaste/src/9/lib/libthr/thread/thr_cond.c:222
#4  0x00000008013d3995 in lldb_private::Condition::Wait
(this=0x7ffffedf5d20, mutex=@0x7ffffedf5d18, abstime=0x7ffffedf5c58,
    timed_out=0x7ffffedf5a1f) at
../tools/lldb/source/Host/common/Condition.cpp:89
#5  0x00000008013d213d in
lldb_private::Predicate<bool>::WaitForValueEqualTo
(this=0x7ffffedf5d10, value=true, abstime=0x7ffffedf5c58,
    timed_out=0x7ffffedf5a1f) at Predicate.h:338
#6  0x000000080143e105 in
lldb_private::Listener::WaitForEventsInternal (this=0x7ffffedf5cb8,
timeout=0x7ffffedf5c58, broadcaster=0x0,
    broadcaster_names=0x0, num_broadcaster_names=0, event_type_mask=0,
event_sp=@0x7ffffedf5ca8) at
../tools/lldb/source/Core/Listener.cpp:433
#7  0x000000080143e4b1 in lldb_private::Listener::WaitForEvent
(this=0x7ffffedf5cb8, timeout=0x7ffffedf5c58,
event_sp=@0x7ffffedf5ca8)
    at ../tools/lldb/source/Core/Listener.cpp:481
#8  0x0000000801747729 in lldb_private::Process::Halt
(this=0x806dbe800, clear_thread_plans=false)
    at ../tools/lldb/source/Target/Process.cpp:3389
#9  0x000000080174bdb8 in
lldb_private::Process::ProcessInputReaderCallback (baton=0x806dbe800,
reader=@0x806feef40,
    notification=lldb::eInputReaderInterrupt, bytes=0x0, bytes_len=0)
at ../tools/lldb/source/Target/Process.cpp:4540
#10 0x0000000801435cdc in lldb_private::InputReader::Notify
(this=0x806feef40, notification=lldb::eInputReaderInterrupt)
    at ../tools/lldb/source/Core/InputReader.cpp:349
#11 0x0000000801408901 in
lldb_private::Debugger::DispatchInputInterrupt (this=0x806c24800) at
../tools/lldb/source/Core/Debugger.cpp:866
#12 0x00000008012bc165 in lldb::SBDebugger::DispatchInputInterrupt
(this=0x7fffffffd3d8) at ../tools/lldb/source/API/SBDebugger.cpp:833
#13 0x0000000000410a44 in sigint_handler (signo=2) at
../tools/lldb/tools/driver/Driver.cpp:1672
#14 0x000000080084b62b in handle_signal (actp=<value optimized out>,
sig=<value optimized out>, info=<value optimized out>,
    ucp=<value optimized out>) at
/home/emaste/src/9/lib/libthr/thread/thr_sig.c:239
#15 0x000000080084b1bf in thr_sighandler (sig=2, info=<value optimized
out>, _ucp=<value optimized out>)
    at /home/emaste/src/9/lib/libthr/thread/thr_sig.c:182
#16 0x00007ffffffff003 in ?? ()
#17 0x000000080084b090 in sigaction () at
/home/emaste/src/9/lib/libthr/thread/thr_sig.c:580
#18 0x000000080084fad5 in cond_wait_common (cond=<value optimized
out>, mutex=0x806d646f0, abstime=0x0, cancel=1)
    at /home/emaste/src/9/lib/libthr/thread/thr_cond.c:243
#19 0x00000008013d39b2 in lldb_private::Condition::Wait
(this=0x806dbeaa8, mutex=@0x806dbeaa0, abstime=0x0,
timed_out=0x7ffffedf6bcf)
    at ../tools/lldb/source/Host/common/Condition.cpp:92
#20 0x00000008013d213d in
lldb_private::Predicate<bool>::WaitForValueEqualTo (this=0x806dbea98,
value=true, abstime=0x0,
    timed_out=0x7ffffedf6bcf) at Predicate.h:338
#21 0x000000080143e105 in
lldb_private::Listener::WaitForEventsInternal (this=0x806dbea40,
timeout=0x0, broadcaster=0x0, broadcaster_names=0x0,
    num_broadcaster_names=0, event_type_mask=0,
event_sp=@0x7ffffedf6e78) at
../tools/lldb/source/Core/Listener.cpp:433
#22 0x000000080143e4b1 in lldb_private::Listener::WaitForEvent
(this=0x806dbea40, timeout=0x0, event_sp=@0x7ffffedf6e78)
    at ../tools/lldb/source/Core/Listener.cpp:481
#23 0x000000080173ddcc in lldb_private::Process::WaitForEventsPrivate
(this=0x806dbe800, timeout=0x0, event_sp=@0x7ffffedf6e78,
    control_only=false) at ../tools/lldb/source/Target/Process.cpp:1423
#24 0x00000008017488e4 in lldb_private::Process::RunPrivateStateThread
(this=0x806dbe800) at ../tools/lldb/source/Target/Process.cpp:4004
#25 0x000000080174833d in lldb_private::Process::PrivateStateThread
(arg=0x806dbe800) at ../tools/lldb/source/Target/Process.cpp:3986
#26 0x00000008013cf29a in ThreadCreateTrampoline (arg=0x806fe5fa0) at
../tools/lldb/source/Host/common/Host.cpp:576
#27 0x000000080084722b in thread_start (curthread=0x806c0f000) at
/home/emaste/src/9/lib/libthr/thread/thr_create.c:284
#28 0x0000000000000000 in ?? ()