Fix assertion in GC_malloc_[atomic_]uncollectable (THREADS case only)

* malloc.c (GC_malloc_uncollectable): Do not check assertion on
hb_n_marks to be zero if multi-threaded; add comment.
* mallocx.c (GC_malloc_atomic_uncollectable): Likewise.

1 files changed, 5 insertions, 1 deletions

diff --git a/malloc.c b/malloc.c
index 0fc28fd1..8e5552f8 100644
--- a/malloc.c
+++ b/malloc.c
@@ -322,7 +322,11 @@ GC_API void * GC_CALL GC_malloc_uncollectable(size_t lb)
         /* mark bits.                                                   */
         LOCK();
         set_mark_bit_from_hdr(hhdr, 0); /* Only object. */
-        GC_ASSERT(hhdr -> hb_n_marks == 0);
+#       ifndef THREADS
+          GC_ASSERT(hhdr -> hb_n_marks == 0);
+                /* This is not guaranteed in the multi-threaded case    */
+                /* because the counter could be updated before locking. */
+#       endif
         hhdr -> hb_n_marks = 1;
         UNLOCK();
         return((void *) op);