[tsan] Avoid false positives with GCD data callbacks

This patch adds synchronization between the creation of the GCD data object and destructor’s execution. It’s far from perfect, because ideally we’d want to synchronize the destruction of the last reference (via dispatch_release) and the destructor’s execution, but intercepting objc_release is problematic.

Differential Revision: http://reviews.llvm.org/D21990

llvm-svn: 274749

1 files changed, 26 insertions, 0 deletions

diff --git a/compiler-rt/lib/tsan/rtl/tsan_libdispatch_mac.cc b/compiler-rt/lib/tsan/rtl/tsan_libdispatch_mac.cc
index cde5ed0a1e4..15805b98de6 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_libdispatch_mac.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_libdispatch_mac.cc
@@ -475,6 +475,32 @@ TSAN_INTERCEPTOR(void, dispatch_apply_f, size_t iterations,
   WRAP(dispatch_apply)(iterations, queue, new_block);
 }
 
+DECLARE_REAL_AND_INTERCEPTOR(void, free, void *ptr)
+DECLARE_REAL_AND_INTERCEPTOR(int, munmap, void *addr, long_t sz)
+
+TSAN_INTERCEPTOR(dispatch_data_t, dispatch_data_create, const void *buffer,
+                 size_t size, dispatch_queue_t q, dispatch_block_t destructor) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_data_create, buffer, size, q, destructor);
+  if ((q == nullptr) || (destructor == DISPATCH_DATA_DESTRUCTOR_DEFAULT))
+    return REAL(dispatch_data_create)(buffer, size, q, destructor);
+
+  if (destructor == DISPATCH_DATA_DESTRUCTOR_FREE)
+    destructor = ^(void) { WRAP(free)((void *)buffer); };
+  else if (destructor == DISPATCH_DATA_DESTRUCTOR_MUNMAP)
+    destructor = ^(void) { WRAP(munmap)((void *)buffer, size); };
+
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  dispatch_block_t heap_block = Block_copy(destructor);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+  tsan_block_context_t *new_context =
+      AllocContext(thr, pc, q, heap_block, &invoke_and_release_block);
+  uptr submit_sync = (uptr)new_context;
+  Release(thr, pc, submit_sync);
+  return REAL(dispatch_data_create)(buffer, size, q, ^(void) {
+    dispatch_callback_wrap(new_context);
+  });
+}
+
 }  // namespace __tsan
 
 #endif  // SANITIZER_MAC