[vm] Double check if thread interrupts are enabled after thread is interrupted

Thread interrupts can be disabled after thread interrupter decided to
interrupt a thread but before thread actually receives and handles
a signal.

This may cause a data race accessing a Sample between profiler which
initializes and adds a Sample and the main thread using
Profiler::sample_block_buffer() in the profiler unit tests.

This is a possible fix for the following benign TSAN error:

WARNING: ThreadSanitizer: data race (pid=5824)
  Write of size 4 at 0x7f53e8e53a98 by thread T6:
    #0 dart::Sample::set_thread_task(dart::Thread::TaskKind) out/ReleaseTSANX64/../../runtime/vm/profiler.h:325:12 (run_vm_tests+0x292cab2)
    #1 dart::SetupSample(dart::Thread*, bool, unsigned long) out/ReleaseTSANX64/../../runtime/vm/profiler.cc:1226:11 (run_vm_tests+0x292cab2)
    #2 dart::Profiler::SampleThread(dart::Thread*, dart::InterruptedThreadState const&) out/ReleaseTSANX64/../../runtime/vm/profiler.cc:1381:7 (run_vm_tests+0x292cab2)
    #3 dart::ThreadInterrupterLinux::ThreadInterruptSignalHandler(int, siginfo_t*, void*) out/ReleaseTSANX64/../../runtime/vm/thread_interrupter_linux.cc:44:5 (run_vm_tests+0x2a064b0)
    #4 __tsan::CallUserSignalHandler(__tsan::ThreadState*, bool, bool, int, __sanitizer::__sanitizer_siginfo*, void*) ../staging/llvm_build/tools/clang/stage2-bins/runtimes/runtimes-x86_64-unknown-linux-gnu-bins/compiler-rt/lib/tsan/rtl/tsan_interceptors_posix.cpp:2122:5 (run_vm_tests+0x1fc057f)
    #5 dart::Mutex::Unlock() out/ReleaseTSANX64/../../runtime/vm/os_thread_linux.cc:367:16 (run_vm_tests+0x2924b89)

  Previous read of size 4 at 0x7f53e8e53a98 by main thread:
    #0 dart::Sample::head_sample() const out/ReleaseTSANX64/../../runtime/vm/profiler.h:350:59 (run_vm_tests+0x22c70e7)
    #1 dart::SampleBuffer::VisitSamples(dart::SampleVisitor*) out/ReleaseTSANX64/../../runtime/vm/profiler.h:589:20 (run_vm_tests+0x22c70e7)
    #2 dart::SampleBlockBuffer::VisitSamples(dart::SampleVisitor*) out/ReleaseTSANX64/../../runtime/vm/profiler.h:752:18 (run_vm_tests+0x22c70e7)
    #3 dart::Dart_TestHelperProfiler_GetSourceReport(dart::Thread*) out/ReleaseTSANX64/../../runtime/vm/profiler_test.cc:2241:26 (run_vm_tests+0x22c70e7)
    #4 dart::Dart_TestProfiler_GetSourceReport() out/ReleaseTSANX64/../../runtime/vm/profiler_test.cc:2206:1 (run_vm_tests+0x22c70e7)
    #5 dart::TestCase::Run() out/ReleaseTSANX64/../../runtime/bin/run_vm_tests.cc:53:3 (run_vm_tests+0x203fe6c)

--- Re-run this test:
python3 tools/test.py -n vm-tsan-linux-release-x64 vm/cc/Profiler_GetSourceReport

Also, this change is a possible fix for #44089.

TEST=ci

Change-Id: I8ad87c340580325cbd6e22b5f068e1e33b0a7d46
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/409460
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

Author: alexmarkov

runtime/vm/profiler.cc

@@ -1361,6 +1361,12 @@ void Profiler::SampleThread(Thread* thread,
   ASSERT(os_thread != nullptr);
   Isolate* isolate = thread->isolate();
 
+  // Double check if interrupts are disabled
+  // after the thread interrupter decided to send a signal.
+  if (!os_thread->ThreadInterruptsEnabled()) {
+    return;
+  }
+
   // Thread is not doing VM work.
   if (thread->task_kind() == Thread::kUnknownTask) {
     counters_.bail_out_unknown_task.fetch_add(1);