[all-commits] [llvm/llvm-project] 7f10ed: [tsan] Fix dead lock when starting StackDepot thre...

[Vitaly Buka via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7f10ed637e53c68ce62b756a3be8546a3dccf751
      https://github.com/llvm/llvm-project/commit/7f10ed637e53c68ce62b756a3be8546a3dccf751
  Author: Vitaly Buka <vitalybuka at google.com>
  Date:   2024-06-25 (Tue, 25 Jun 2024)

  Changed paths:
    M compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp

  Log Message:
  -----------
  [tsan] Fix dead lock when starting StackDepot thread (#96456)

Sometime tsan runtimes calls, like
`__tsan_mutex_create ()`, need to store a stack
in the StackDepot, and the Depot may need to start
and maintenance thread.

Example:
```
__sanitizer::FutexWait ()
__sanitizer::Semaphore::Wait ()
__sanitizer::Mutex::Lock ()
__tsan::SlotLock ()
__tsan::SlotLocker::SlotLocker ()
__tsan::Acquire ()
__tsan::CallUserSignalHandler ()
__tsan::ProcessPendingSignalsImpl ()
__tsan::ProcessPendingSignals ()
__tsan::ScopedInterceptor::~ScopedInterceptor ()
___interceptor_mmap ()
pthread_create ()
__sanitizer::internal_start_thread ()
__sanitizer::(anonymous namespace)::CompressThread::NewWorkNotify ()
__sanitizer::StackDepotNode::store ()
__sanitizer::StackDepotBase<__sanitizer::StackDepotNode, 1, 20>::Put ()
__tsan::CurrentStackId ()
__tsan::MutexCreate ()
__tsan_mutex_create ()
```

pthread_create() implementation may hit other
interceptors recursively, which may invoke
ProcessPendingSignals, which deadlocks.

Alternative solution could be block interceptors
closer to TSAN runtime API function, like
`__tsan_mutex_create`, or just before
`StackDepotPut``, but it's not needed for most
calls, only when new thread is created using
`real_pthread_create`.

I don't see a reasonable way to create a
regression test.



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