[compiler-rt] r319305 - Defer StartBackgroundThread() and StopBackgroundThread() in TSan

[Kamil Rytarowski via llvm-commits]

Author: kamil
Date: Wed Nov 29 02:23:59 2017
New Revision: 319305

URL: http://llvm.org/viewvc/llvm-project?rev=319305&view=rev
Log:
Defer StartBackgroundThread() and StopBackgroundThread() in TSan

Summary:
NetBSD cannot spawn new POSIX thread entities in early
libc and libpthread initialization stage. Defer this to the point
of intercepting the first pthread_create(3) call.

This is the last change that makes Thread Sanitizer functional
on NetBSD/amd64 without downstream patches.

********************
Testing Time: 64.91s
********************
Failing Tests (5):
    ThreadSanitizer-x86_64 :: dtls.c
    ThreadSanitizer-x86_64 :: ignore_lib5.cc
    ThreadSanitizer-x86_64 :: ignored-interceptors-mmap.cc
    ThreadSanitizer-x86_64 :: mutex_lock_destroyed.cc
    ThreadSanitizer-x86_64 :: vfork.cc

  Expected Passes    : 290
  Expected Failures  : 1
  Unsupported Tests  : 83
  Unexpected Failures: 5

Sponsored by <The NetBSD Foundation>

Reviewers: joerg, eugenis, dvyukov, vitalybuka

Reviewed By: dvyukov

Subscribers: kubamracek, llvm-commits, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D40583

Modified:
    compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
    compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc
    compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc?rev=319305&r1=319304&r2=319305&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_interceptors.cc Wed Nov 29 02:23:59 2017
@@ -974,6 +974,9 @@ extern "C" void *__tsan_thread_start_fun
 TSAN_INTERCEPTOR(int, pthread_create,
     void *th, void *attr, void *(*callback)(void*), void * param) {
   SCOPED_INTERCEPTOR_RAW(pthread_create, th, attr, callback, param);
+
+  MaybeSpawnBackgroundThread();
+
   if (ctx->after_multithreaded_fork) {
     if (flags()->die_after_fork) {
       Report("ThreadSanitizer: starting new threads after multi-threaded "

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc?rev=319305&r1=319304&r2=319305&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.cc Wed Nov 29 02:23:59 2017
@@ -384,13 +384,6 @@ void Initialize(ThreadState *thr) {
 #if !SANITIZER_GO
   InitializeLibIgnore();
   Symbolizer::GetOrInit()->AddHooks(EnterSymbolizer, ExitSymbolizer);
-  // On MIPS, TSan initialization is run before
-  // __pthread_initialize_minimal_internal() is finished, so we can not spawn
-  // new threads.
-#ifndef __mips__
-  StartBackgroundThread();
-  SetSandboxingCallback(StopBackgroundThread);
-#endif
 #endif
 
   VPrintf(1, "***** Running under ThreadSanitizer v2 (pid %d) *****\n",
@@ -419,6 +412,21 @@ void Initialize(ThreadState *thr) {
   OnInitialize();
 }
 
+void MaybeSpawnBackgroundThread() {
+  // On MIPS, TSan initialization is run before
+  // __pthread_initialize_minimal_internal() is finished, so we can not spawn
+  // new threads.
+#if !SANITIZER_GO && !defined(__mips__)
+  static atomic_uint32_t bg_thread = {};
+  if (atomic_load(&bg_thread, memory_order_relaxed) == 0 &&
+      atomic_exchange(&bg_thread, 1, memory_order_relaxed) == 0) {
+    StartBackgroundThread();
+    SetSandboxingCallback(StopBackgroundThread);
+  }
+#endif
+}
+
+
 int Finalize(ThreadState *thr) {
   bool failed = false;
 

Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h?rev=319305&r1=319304&r2=319305&view=diff
==============================================================================
--- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h (original)
+++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl.h Wed Nov 29 02:23:59 2017
@@ -700,6 +700,7 @@ void PrintCurrentStack(ThreadState *thr,
 void PrintCurrentStackSlow(uptr pc);  // uses libunwind
 
 void Initialize(ThreadState *thr);
+void MaybeSpawnBackgroundThread();
 int Finalize(ThreadState *thr);
 
 void OnUserAlloc(ThreadState *thr, uptr pc, uptr p, uptr sz, bool write);