Fix infinite loop in disable_gc_for_dlopen and GC_wait_for_gc_completion

(a cherry-pick of commit 2dff48cb3 from 'release-8_2')

Issue #257 (bdwgc).

* alloc.c (GC_collect_a_little_inner): Call GC_mark_some() (in a loop)
even if GC_dont_gc.
* alloc.c (GC_collect_a_little, GC_allocobj): Do not call
GC_collect_a_little_inner() if GC_dont_gc.
* tests/test.c (check_heap_stats): Do not call GC_collect_a_little()
(repeatedly) if GC_is_disabled().

2 files changed, 10 insertions, 7 deletions

diff --git a/alloc.c b/alloc.c
index 9e7f9d24..0aef299c 100644
--- a/alloc.c
+++ b/alloc.c
@@ -621,8 +621,6 @@ GC_INNER void GC_collect_a_little_inner(int n)
     IF_CANCEL(int cancel_state;)
 
     GC_ASSERT(I_HOLD_LOCK());
-    if (GC_dont_gc) return;
-
     DISABLE_CANCEL(cancel_state);
     if (GC_incremental && GC_collection_in_progress()) {
         int i;
@@ -630,6 +628,7 @@ GC_INNER void GC_collect_a_little_inner(int n)
 
         for (i = GC_deficit; i < max_deficit; i++) {
             if (GC_mark_some((ptr_t)0)) {
+                if (GC_dont_gc) break;
                 /* Need to finish a collection */
 #               ifdef SAVE_CALL_CHAIN
                     GC_save_callers(GC_last_stack);
@@ -661,7 +660,7 @@ GC_INNER void GC_collect_a_little_inner(int n)
             if (GC_deficit < 0)
                 GC_deficit = 0;
         }
-    } else {
+    } else if (!GC_dont_gc) {
         GC_maybe_gc();
     }
     RESTORE_CANCEL(cancel_state);
@@ -676,7 +675,9 @@ GC_API int GC_CALL GC_collect_a_little(void)
     DCL_LOCK_STATE;
 
     LOCK();
-    GC_collect_a_little_inner(1);
+    if (!GC_dont_gc) {
+      GC_collect_a_little_inner(1);
+    }
     result = (int)GC_collection_in_progress();
     UNLOCK();
     if (!result && GC_debugging_started) GC_print_all_smashed();
@@ -1521,7 +1522,8 @@ GC_INNER ptr_t GC_allocobj(size_t gran, int kind)
     while (*flh == 0) {
       ENTER_GC();
 #     ifndef GC_DISABLE_INCREMENTAL
-        if (GC_incremental && GC_time_limit != GC_TIME_UNLIMITED) {
+        if (GC_incremental && GC_time_limit != GC_TIME_UNLIMITED
+            && !GC_dont_gc) {
           /* True incremental mode, not just generational.      */
           /* Do our share of marking work.                      */
           GC_collect_a_little_inner(1);
@@ -1538,7 +1540,7 @@ GC_INNER ptr_t GC_allocobj(size_t gran, int kind)
         if (*flh == 0) {
           ENTER_GC();
           if (GC_incremental && GC_time_limit == GC_TIME_UNLIMITED
-              && !tried_minor) {
+              && !tried_minor && !GC_dont_gc) {
             GC_collect_a_little_inner(1);
             tried_minor = TRUE;
           } else {
diff --git a/tests/test.c b/tests/test.c
index 0db0ac02..f5ed27ab 100644
--- a/tests/test.c
+++ b/tests/test.c
@@ -1710,7 +1710,8 @@ void check_heap_stats(void)
 #   endif
     /* Garbage collect repeatedly so that all inaccessible objects      */
     /* can be finalized.                                                */
-      while (GC_collect_a_little()) { }
+      if (!GC_is_disabled())
+        while (GC_collect_a_little()) { }
       for (i = 0; i < 16; i++) {
         GC_gcollect();
 #       ifndef GC_NO_FINALIZATION