[PATCH] D40262: Correct NetBSD support in pthread_once(3)/TSan

[Kamil Rytarowski via Phabricator via llvm-commits]

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

The pthread_once(3)/NetBSD type is built with the following structure:

struct __pthread_once_st {
 pthread_mutex_t pto_mutex;
 int pto_done;
};

Set the pto_done position as shifted by __sanitizer::pthread_t_sz
from the beginning of the pthread_once struct.

This corrects deadlocks when the pthread_once(3) function
is used.

While there, switch if(SANITIZER_OS) constructs to ifdefs for simplicity.

Sponsored by <The NetBSD Foundation>


Repository:
  rL LLVM

https://reviews.llvm.org/D40262

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
@@ -1354,10 +1354,16 @@
   if (o == 0 || f == 0)
     return errno_EINVAL;
   atomic_uint32_t *a;
-  if (!SANITIZER_MAC)
-    a = static_cast<atomic_uint32_t*>(o);
-  else  // On OS X, pthread_once_t has a header with a long-sized signature.
-    a = static_cast<atomic_uint32_t*>((void *)((char *)o + sizeof(long_t)));
+
+#if SANITIZER_MAC
+  a = static_cast<atomic_uint32_t*>((void *)((char *)o + sizeof(long_t)));
+#elif SANITIZER_NETBSD
+  a = static_cast<atomic_uint32_t*>
+        ((void *)((char *)o + __sanitizer::pthread_t_sz));
+#else
+  a = static_cast<atomic_uint32_t*>(o);
+#endif
+
   u32 v = atomic_load(a, memory_order_acquire);
   if (v == 0 && atomic_compare_exchange_strong(a, &v, 1,
                                                memory_order_relaxed)) {


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