[PATCH] tsan: fix signal handling during stop-the-world

[Sergey Matveev]

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Comment at: lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc:253
@@ -252,3 @@
-    new_sigaction.sa_flags = SA_ONSTACK | SA_SIGINFO;
-    internal_sigfillset(&new_sigaction.sa_mask);
-    internal_sigaction_norestorer(kUnblockedSignals[signal_index],
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Why did you remove this?

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Comment at: lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc:268
@@ -268,1 +267,3 @@
+  // it can call KillAllThreads on the destroyed variable.
+  SetDieCallback(old_die_callback);
   thread_suspender_instance = NULL;
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We shouldn't ever run TracerThreadDieCallback() from other threads. It wouldn't work anyway.

I think TracerThreadDieCallback() should check that internal_getpid() == stoptheworld_tracer_pid. If not, just call the old callback.

http://reviews.llvm.org/D7722

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