Fix infinite loop in disable_gc_for_dlopen and GC_wait_for_gc_completion

(a cherry-pick of commit 2e5646ba3 from 'master')

Issue #257 (bdwgc).

* alloc.c (GC_start_incremental_collection, GC_collect_a_little): Do
not call GC_collect_a_little_inner() and ENTER/EXIT_GC() if GC_dont_gc.
* alloc.c (GC_collect_a_little_inner): Call GC_mark_some() (in a loop)
even if GC_dont_gc.
* alloc.c (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, 17 insertions, 13 deletions

diff --git a/alloc.c b/alloc.c
index 0a4435b4..a2505ad5 100644
--- a/alloc.c
+++ b/alloc.c
@@ -417,9 +417,11 @@ GC_API void GC_CALL GC_start_incremental_collection(void)
     if (!GC_incremental) return;
     LOCK();
     GC_should_start_incremental_collection = TRUE;
-    ENTER_GC();
-    GC_collect_a_little_inner(1);
-    EXIT_GC();
+    if (!GC_dont_gc) {
+      ENTER_GC();
+      GC_collect_a_little_inner(1);
+      EXIT_GC();
+    }
     UNLOCK();
 # endif
 }
@@ -715,8 +717,6 @@ 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;
@@ -734,7 +734,7 @@ GC_INNER void GC_collect_a_little_inner(int n)
             GC_parallel_mark_disabled = FALSE;
 #       endif
 
-        if (i < max_deficit) {
+        if (i < max_deficit && !GC_dont_gc) {
             /* Need to finish a collection.     */
 #           ifdef SAVE_CALL_CHAIN
                 GC_save_callers(GC_last_stack);
@@ -765,7 +765,7 @@ 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);
@@ -780,9 +780,11 @@ GC_API int GC_CALL GC_collect_a_little(void)
     DCL_LOCK_STATE;
 
     LOCK();
-    ENTER_GC();
-    GC_collect_a_little_inner(1);
-    EXIT_GC();
+    if (!GC_dont_gc) {
+      ENTER_GC();
+      GC_collect_a_little_inner(1);
+      EXIT_GC();
+    }
     result = (int)GC_collection_in_progress();
     UNLOCK();
     if (!result && GC_debugging_started) GC_print_all_smashed();
@@ -1759,7 +1761,8 @@ 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);
@@ -1782,7 +1785,7 @@ GC_INNER ptr_t GC_allocobj(size_t gran, int kind)
         if (NULL == *flh) {
           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 c14866e3..e3b91808 100644
--- a/tests/test.c
+++ b/tests/test.c
@@ -1753,7 +1753,8 @@ 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