add locking in mkWeakForeignEnv#

diff --git a/rts/PrimOps.cmm b/rts/PrimOps.cmm
index b88ca7a..b4dfb6d 100644 (file)
--- a/rts/PrimOps.cmm
+++ b/rts/PrimOps.cmm
@@ -377,8 +377,10 @@ stg_mkWeakForeignEnvzh
   StgWeak_finalizer(w)  = stg_NO_FINALIZER_closure;
   StgWeak_cfinalizer(w) = p;
 
+  ACQUIRE_LOCK(sm_mutex);
   StgWeak_link(w)   = W_[weak_ptr_list];
   W_[weak_ptr_list] = w;
+  RELEASE_LOCK(sm_mutex);
 
   IF_DEBUG(weak, foreign "C" debugBelch(stg_weak_msg,w) []);