It's obviously the only thread, since frame #8 acquired the mutex first and frame #6 tries to acquire it again.
I changed it to a recursive mutex, and now it crashes on a stack overflow instead of deadlocking. Here's an excerpt of the stack, from the initially calling frame (StackFrameList::GetFramesUpTo): #12543 UnwindMacOSXFrameBackchain::DoGetFrameInfoAtIndex(unsigned int, unsigned long long&, unsigned long long&) at lldb/source/Plugins/Process/Utility/UnwindMacOSXFrameBackchain.cpp:59 #12544 lldb_private::Unwind::GetFrameInfoAtIndex(unsigned int, unsigned long long&, unsigned long long&) at lldb/include/lldb/Target/Unwind.h:78 #12545 lldb_private::StackFrameList::GetFramesUpTo(unsigned int) at lldb/source/Target/StackFrameList.cpp:332 #12546 lldb_private::StackFrameList::GetFrameAtIndex(unsigned int) at lldb/source/Target/StackFrameList.cpp:521 #12547 lldb_private::Thread::GetStackFrameAtIndex(unsigned int) at lldb/include/lldb/Target/Thread.h:357 #12548 UnwindMacOSXFrameBackchain::DoGetFrameCount() at lldb/source/Plugins/Process/Utility/UnwindMacOSXFrameBackchain.cpp:45 #12549 lldb_private::Unwind::GetFrameCount() at lldb/include/lldb/Target/Unwind.h:52 #12550 UnwindMacOSXFrameBackchain::DoGetFrameInfoAtIndex(unsigned int, unsigned long long&, unsigned long long&) at lldb/source/Plugins/Process/Utility/UnwindMacOSXFrameBackchain.cpp:59 #12551 lldb_private::Unwind::GetFrameInfoAtIndex(unsigned int, unsigned long long&, unsigned long long&) at lldb/include/lldb/Target/Unwind.h:78 #12552 lldb_private::StackFrameList::GetFramesUpTo(unsigned int) at lldb/source/Target/StackFrameList.cpp:332 #12553 lldb_private::StackFrameList::GetFrameAtIndex(unsigned int) at lldb/source/Target/StackFrameList.cpp:521 #12554 lldb_private::Thread::GetStackFrameAtIndex(unsigned int) at lldb/include/lldb/Target/Thread.h:357 #12555 UnwindMacOSXFrameBackchain::DoGetFrameCount() at lldb/source/Plugins/Process/Utility/UnwindMacOSXFrameBackchain.cpp:45 #12556 lldb_private::Unwind::GetFrameCount() at lldb/include/lldb/Target/Unwind.h:52 #12557 UnwindMacOSXFrameBackchain::DoGetFrameInfoAtIndex(unsigned int, unsigned long long&, unsigned long long&) at lldb/source/Plugins/Process/Utility/UnwindMacOSXFrameBackchain.cpp:59 #12558 lldb_private::Unwind::GetFrameInfoAtIndex(unsigned int, unsigned long long&, unsigned long long&) at lldb/include/lldb/Target/Unwind.h:78 #12559 lldb_private::StackFrameList::GetFramesUpTo(unsigned int) at lldb/source/Target/StackFrameList.cpp:304 Le 2013-08-22 à 16:53:15, "Malea, Daniel" <[email protected]> a écrit : > Hmm, based on the stack trace you provided, it seems that m_unwind_mutex > should be initialized as a recursive mutex, just like Process::m_thread_mutex. > > Can you try to change the initialization of m_unwind_mutex in Unwind.h to > match that of Process:m_thread_mutex, and see if it helps? If not, then it > means some other thread is holding that mutex and more investigation is > required… > > Cheers, > Dan > > From: Félix Cloutier <[email protected]<mailto:[email protected]>> > Date: Thursday, 22 August, 2013 4:26 PM > To: "[email protected]<mailto:[email protected]>" > <[email protected]<mailto:[email protected]>> > Subject: [lldb-dev] LLDB deadlocks trying to unwind > > LLDB, connected to a stub I'm building, is trying to produce a stack trace of > my stopped program but deadlocks instead: > > #0 __psynch_mutexwait () > #1 pthread_mutex_lock () > #2 lldb_private::Mutex::Lock() at lldb/source/Host/common/Mutex.cpp:281 > #3 lldb_private::Mutex::Locker::Lock(lldb_private::Mutex&) at > lldb/source/Host/common/Mutex.cpp:152 > #4 lldb_private::Mutex::Locker::Locker(lldb_private::Mutex&) at > lldb/source/Host/common/Mutex.cpp:112 > #5 lldb_private::Mutex::Locker::Locker(lldb_private::Mutex&) at > lldb/source/Host/common/Mutex.cpp:113 > #6 lldb_private::Unwind::GetFrameCount() at > lldb/include/lldb/Target/Unwind.h:51 > #7 UnwindMacOSXFrameBackchain::DoGetFrameInfoAtIndex(unsigned int, unsigned > long long&, unsigned long long&) at > lldb/source/Plugins/Process/Utility/UnwindMacOSXFrameBackchain.cpp:59 > #8 lldb_private::Unwind::GetFrameInfoAtIndex(unsigned int, unsigned long > long&, unsigned long long&) at lldb/include/lldb/Target/Unwind.h:78 > #9 lldb_private::StackFrameList::GetFramesUpTo(unsigned int) at > lldb/source/Target/StackFrameList.cpp:304 > #10 lldb_private::StackFrameList::ResetCurrentInlinedDepth() at > lldb/source/Target/StackFrameList.cpp:110 > #11 lldb_private::StackFrameList::CalculateCurrentInlinedDepth() at > lldb/source/Target/StackFrameList.cpp:79 > #12 lldb_private::Thread::ShouldStop(lldb_private::Event*) at > lldb/source/Target/Thread.cpp:752 > #13 lldb_private::ThreadList::ShouldStop(lldb_private::Event*) at > lldb/source/Target/ThreadList.cpp:298 > #14 lldb_private::Process::ShouldBroadcastEvent(lldb_private::Event*) at > lldb/source/Target/Process.cpp:3707 > #15 > lldb_private::Process::HandlePrivateEvent(std::__1::shared_ptr<lldb_private::Event>&) > at lldb/source/Target/Process.cpp:3936 > #16 lldb_private::Process::ConnectRemote(lldb_private::Stream*, char const*) > at lldb/source/Target/Process.cpp:3257 > #17 CommandObjectProcessConnect::DoExecute(lldb_private::Args&, > lldb_private::CommandReturnObject&) at > lldb/source/Commands/CommandObjectProcess.cpp:1173 > #18 lldb_private::CommandObjectParsed::Execute(char const*, > lldb_private::CommandReturnObject&) at > lldb/source/Interpreter/CommandObject.cpp:1038 > #19 lldb_private::CommandInterpreter::HandleCommand(char const*, > lldb_private::LazyBool, lldb_private::CommandReturnObject&, > lldb_private::ExecutionContext*, bool, bool) at > lldb/source/Interpreter/CommandInterpreter.cpp:1825 > #20 lldb_private::CommandObjectRegexCommand::DoExecute(char const*, > lldb_private::CommandReturnObject&) at > lldb/source/Interpreter/CommandObjectRegexCommand.cpp:89 > #21 lldb_private::CommandObjectRaw::Execute(char const*, > lldb_private::CommandReturnObject&) at > lldb/source/Interpreter/CommandObject.cpp:1064 > #22 lldb_private::CommandInterpreter::HandleCommand(char const*, > lldb_private::LazyBool, lldb_private::CommandReturnObject&, > lldb_private::ExecutionContext*, bool, bool) at > lldb/source/Interpreter/CommandInterpreter.cpp:1825 > #23 lldb::SBCommandInterpreter::HandleCommand(char const*, > lldb::SBCommandReturnObject&, bool) at > lldb/source/API/SBCommandInterpreter.cpp:122 > #24 Driver::HandleIOEvent(lldb::SBEvent const&) at > lldb/tools/driver/Driver.cpp:1083 > #25 Driver::MainLoop() at lldb/tools/driver/Driver.cpp:1556 > #26 main at lldb/tools/driver/Driver.cpp:1727 > #27 start () > > #8 locks m_unwind_mutex and #6 tries to do the same thing. > > The code path is unconditional (calling GetFrameInfoAtIndex with a > UnwindMacOSXFrameBackchain can only end in a deadlock, from what I can see), > so I'm not sure how I can prevent this from happening. > > Félix _______________________________________________ lldb-dev mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
