[PATCH] D39618: Correct detection of a thread termination

[Kamil Rytarowski via Phabricator via llvm-commits]

krytarowski created this revision.
krytarowski added a project: Sanitizers.
Herald added a subscriber: kubamracek.

Stop using the Linux solution with pthread_key_create(3).
This approach does not work on NetBSD, because calling
the thread destructor is not the latest operation on a POSIX
thread entity. NetBSD's libpthread still calls at least
pthread_mutex_lock and pthread_mutex_unlock.

Detect _lwp_exit(2) call as it is really the latest operation
called from a detaching POSIX thread.

This resolves one set of crashes observed in
the Thread Sanitizer execution.

Sponsored by <The NetBSD Foundation>


Repository:
  rL LLVM

https://reviews.llvm.org/D39618

Files:
  lib/tsan/rtl/tsan_interceptors.cc


Index: lib/tsan/rtl/tsan_interceptors.cc
===================================================================
--- lib/tsan/rtl/tsan_interceptors.cc
+++ lib/tsan/rtl/tsan_interceptors.cc
@@ -265,7 +265,7 @@
   return ctx;
 }
 
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_NETBSD
 static unsigned g_thread_finalize_key;
 #endif
 
@@ -866,7 +866,7 @@
 }
 }  // namespace __tsan
 
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_NETBSD
 static void thread_finalize(void *v) {
   uptr iter = (uptr)v;
   if (iter > 1) {
@@ -896,7 +896,7 @@
     ThreadState *thr = cur_thread();
     // Thread-local state is not initialized yet.
     ScopedIgnoreInterceptors ignore;
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_NETBSD
     ThreadIgnoreBegin(thr, 0);
     if (pthread_setspecific(g_thread_finalize_key,
                             (void *)GetPthreadDestructorIterations())) {
@@ -2445,6 +2445,17 @@
 }
 #endif
 
+#if SANITIZER_NETBSD
+TSAN_INTERCEPTOR(void, _lwp_exit) {
+  SCOPED_TSAN_INTERCEPTOR(_lwp_exit);
+  REAL(_lwp_exit)();
+  DestroyThreadState();
+}
+#define TSAN_MAYBE_INTERCEPT__LWP_EXIT TSAN_INTERCEPT(_lwp_exit)
+#else
+#define TSAN_MAYBE_INTERCEPT__LWP_EXIT
+#endif
+
 namespace __tsan {
 
 static void finalize(void *arg) {
@@ -2613,6 +2624,8 @@
   TSAN_INTERCEPT(__tls_get_addr);
 #endif
 
+  TSAN_MAYBE_INTERCEPT__LWP_EXIT;
+
 #if !SANITIZER_MAC && !SANITIZER_ANDROID
   // Need to setup it, because interceptors check that the function is resolved.
   // But atexit is emitted directly into the module, so can't be resolved.
@@ -2624,7 +2637,7 @@
     Die();
   }
 
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_NETBSD
   if (pthread_key_create(&g_thread_finalize_key, &thread_finalize)) {
     Printf("ThreadSanitizer: failed to create thread key\n");
     Die();


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