Add TSAN support (#541)

src/bytes_mut.rs

@@ -16,7 +16,7 @@ use crate::buf::{IntoIter, UninitSlice};
 use crate::bytes::Vtable;
 #[allow(unused)]
 use crate::loom::sync::atomic::AtomicMut;
-use crate::loom::sync::atomic::{self, AtomicPtr, AtomicUsize, Ordering};
+use crate::loom::sync::atomic::{AtomicPtr, AtomicUsize, Ordering};
 use crate::{Buf, BufMut, Bytes};
 
 /// A unique reference to a contiguous slice of memory.
@@ -1288,7 +1288,10 @@ unsafe fn release_shared(ptr: *mut Shared) {
     // > "acquire" operation before deleting the object.
     //
     // [1]: (www.boost.org/doc/libs/1_55_0/doc/html/atomic/usage_examples.html)
-    atomic::fence(Ordering::Acquire);
+    //
+    // Thread sanitizer does not support atomic fences. Use an atomic load
+    // instead.
+    (*ptr).ref_count.load(Ordering::Acquire);
 
     // Drop the data
     Box::from_raw(ptr);