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[sanitizer] Fix deadlock in StopTheWorld. The tracer thread in StopTheWorld could wait on a mutex forever if the parent process died before unlocking it. Use PR_SET_PDEATHSIG so that the parent would kill the child in this scenario.
ClosedPublic

Authored by earthdok on Oct 8 2013, 8:58 AM.

Reviewers

dvyukov

LGTM

Path

Size

lib/

sanitizer_common/

5 lines

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	// Size of alternative stack for signal handlers in the tracer thread.			// Size of alternative stack for signal handlers in the tracer thread.
	static const int kHandlerStackSize = 4096;			static const int kHandlerStackSize = 4096;

	// This function will be run as a cloned task.			// This function will be run as a cloned task.
	static int TracerThread(void* argument) {			static int TracerThread(void* argument) {
	TracerThreadArgument *tracer_thread_argument =			TracerThreadArgument *tracer_thread_argument =
	(TracerThreadArgument *)argument;			(TracerThreadArgument *)argument;

				internal_prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
				// Check if parent is already dead.
				if (internal_getppid() == 1)
				internal__exit(4);

	// Wait for the parent thread to finish preparations.			// Wait for the parent thread to finish preparations.
	tracer_thread_argument->mutex.Lock();			tracer_thread_argument->mutex.Lock();
	tracer_thread_argument->mutex.Unlock();			tracer_thread_argument->mutex.Unlock();

	SetDieCallback(TracerThreadDieCallback);			SetDieCallback(TracerThreadDieCallback);

	ThreadSuspender thread_suspender(internal_getppid());			ThreadSuspender thread_suspender(internal_getppid());
	// Global pointer for the signal handler.			// Global pointer for the signal handler.
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