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Revision tags: llvmorg-18.1.8, llvmorg-18.1.7, llvmorg-18.1.6, llvmorg-18.1.5, llvmorg-18.1.4, llvmorg-18.1.3, llvmorg-18.1.2, llvmorg-18.1.1, llvmorg-18.1.0, llvmorg-18.1.0-rc4, llvmorg-18.1.0-rc3, llvmorg-18.1.0-rc2, llvmorg-18.1.0-rc1, llvmorg-19-init, llvmorg-17.0.6, llvmorg-17.0.5, llvmorg-17.0.4, llvmorg-17.0.3, llvmorg-17.0.2, llvmorg-17.0.1, llvmorg-17.0.0, llvmorg-17.0.0-rc4, llvmorg-17.0.0-rc3, llvmorg-17.0.0-rc2, llvmorg-17.0.0-rc1, llvmorg-18-init, llvmorg-16.0.6, llvmorg-16.0.5, llvmorg-16.0.4, llvmorg-16.0.3, llvmorg-16.0.2, llvmorg-16.0.1, llvmorg-16.0.0, llvmorg-16.0.0-rc4, llvmorg-16.0.0-rc3, llvmorg-16.0.0-rc2, llvmorg-16.0.0-rc1, llvmorg-17-init, llvmorg-15.0.7, llvmorg-15.0.6, llvmorg-15.0.5, llvmorg-15.0.4, llvmorg-15.0.3, working, llvmorg-15.0.2, llvmorg-15.0.1, llvmorg-15.0.0, llvmorg-15.0.0-rc3, llvmorg-15.0.0-rc2, llvmorg-15.0.0-rc1, llvmorg-16-init, llvmorg-14.0.6, llvmorg-14.0.5, llvmorg-14.0.4, llvmorg-14.0.3, llvmorg-14.0.2, llvmorg-14.0.1, llvmorg-14.0.0, llvmorg-14.0.0-rc4, llvmorg-14.0.0-rc3 |
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10222764 |
| 02-Mar-2022 |
Jonas Devlieghere <jonas@devlieghere.com> |
[lldb] Avoid data race in IOHandlerProcessSTDIO
This patch fixes a data race in IOHandlerProcessSTDIO. The race is
happens between the main thread and the event handling thread. The main
thread is r
[lldb] Avoid data race in IOHandlerProcessSTDIO
This patch fixes a data race in IOHandlerProcessSTDIO. The race is
happens between the main thread and the event handling thread. The main
thread is running the IOHandler (IOHandlerProcessSTDIO::Run()) when an
event comes in that makes us pop the process IO handler which involves
cancelling the IOHandler (IOHandlerProcessSTDIO::Cancel). The latter
calls SetIsDone(true) which modifies m_is_done. At the same time, we
have the main thread reading the variable through GetIsDone().
This patch avoids the race by using a mutex to synchronize the two
threads. On the event thread, in IOHandlerProcessSTDIO ::Cancel method,
we obtain the lock before changing the value of m_is_done. On the main
thread, in IOHandlerProcessSTDIO::Run(), we obtain the lock before
reading the value of m_is_done. Additionally, we delay calling SetIsDone
until after the loop exists, to avoid a potential race between the two
writes.
Write of size 1 at 0x00010b66bb68 by thread T7 (mutexes: write M2862, write M718324145051843688):
#0 lldb_private::IOHandler::SetIsDone(bool) IOHandler.h:90 (liblldb.15.0.0git.dylib:arm64+0x971d84)
#1 IOHandlerProcessSTDIO::Cancel() Process.cpp:4382 (liblldb.15.0.0git.dylib:arm64+0x5ddfec)
#2 lldb_private::Debugger::PopIOHandler(std::__1::shared_ptr<lldb_private::IOHandler> const&) Debugger.cpp:1156 (liblldb.15.0.0git.dylib:arm64+0x3cb2a8)
#3 lldb_private::Debugger::RemoveIOHandler(std::__1::shared_ptr<lldb_private::IOHandler> const&) Debugger.cpp:1063 (liblldb.15.0.0git.dylib:arm64+0x3cbd2c)
#4 lldb_private::Process::PopProcessIOHandler() Process.cpp:4487 (liblldb.15.0.0git.dylib:arm64+0x5c583c)
#5 lldb_private::Debugger::HandleProcessEvent(std::__1::shared_ptr<lldb_private::Event> const&) Debugger.cpp:1549 (liblldb.15.0.0git.dylib:arm64+0x3ceabc)
#6 lldb_private::Debugger::DefaultEventHandler() Debugger.cpp:1622 (liblldb.15.0.0git.dylib:arm64+0x3cf2c0)
#7 std::__1::__function::__func<lldb_private::Debugger::StartEventHandlerThread()::$_2, std::__1::allocator<lldb_private::Debugger::StartEventHandlerThread()::$_2>, void* ()>::operator()() function.h:352 (liblldb.15.0.0git.dylib:arm64+0x3d1bd8)
#8 lldb_private::HostNativeThreadBase::ThreadCreateTrampoline(void*) HostNativeThreadBase.cpp:62 (liblldb.15.0.0git.dylib:arm64+0x4c71ac)
#9 lldb_private::HostThreadMacOSX::ThreadCreateTrampoline(void*) HostThreadMacOSX.mm:18 (liblldb.15.0.0git.dylib:arm64+0x29ef544)
Previous read of size 1 at 0x00010b66bb68 by main thread:
#0 lldb_private::IOHandler::GetIsDone() IOHandler.h:92 (liblldb.15.0.0git.dylib:arm64+0x971db8)
#1 IOHandlerProcessSTDIO::Run() Process.cpp:4339 (liblldb.15.0.0git.dylib:arm64+0x5ddc7c)
#2 lldb_private::Debugger::RunIOHandlers() Debugger.cpp:982 (liblldb.15.0.0git.dylib:arm64+0x3cb48c)
#3 lldb_private::CommandInterpreter::RunCommandInterpreter(lldb_private::CommandInterpreterRunOptions&) CommandInterpreter.cpp:3298 (liblldb.15.0.0git.dylib:arm64+0x506478)
#4 lldb::SBDebugger::RunCommandInterpreter(bool, bool) SBDebugger.cpp:1166 (liblldb.15.0.0git.dylib:arm64+0x53604)
#5 Driver::MainLoop() Driver.cpp:634 (lldb:arm64+0x100006294)
#6 main Driver.cpp:853 (lldb:arm64+0x100007344)
Differential revision: https://reviews.llvm.org/D120762
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