Fix missing lock when GC_generate_random_valid_address is called

Issue #414 (bdwgc).

* dbg_mlc.c [KEEP_BACK_PTRS] (GC_generate_random_backtrace_no_gc):
Remove definition.
* dbg_mlc.c [KEEP_BACK_PTRS] (GC_generate_random_backtrace): Declare
current local variable; expand GC_generate_random_backtrace_no_gc()
manually.
* finalize.c [KEEP_BACK_PTRS] (GC_notify_or_invoke_finalizers):
Likewise.
* dbg_mlc.c [KEEP_BACK_PTRS] (GC_generate_random_backtrace): Wrap
GC_generate_random_valid_address() call into LOCK/UNLOCK.
* finalize.c [KEEP_BACK_PTRS] (GC_notify_or_invoke_finalizers):
UNLOCK after GC_generate_random_valid_address() call.
* include/private/gc_priv.h [KEEP_BACK_PTRS]
(GC_generate_random_backtrace_no_gc): Remove declaration.

3 files changed, 14 insertions, 13 deletions

diff --git a/dbg_mlc.c b/dbg_mlc.c
index 1ffee0f4..af34b486 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -245,24 +245,23 @@
     out:;
   }
 
-  /* Force a garbage collection and generate/print a backtrace  */
-  /* from a random heap address.                                */
-  GC_INNER void GC_generate_random_backtrace_no_gc(void)
-  {
-    void * current;
-    current = GC_generate_random_valid_address();
-    GC_printf("\n****Chosen address %p in object\n", current);
-    GC_print_backtrace(current);
-  }
-
   GC_API void GC_CALL GC_generate_random_backtrace(void)
   {
+    void *current;
+    DCL_LOCK_STATE;
+
     if (GC_try_to_collect(GC_never_stop_func) == 0) {
       GC_err_printf("Cannot generate a backtrace: "
                     "garbage collection is disabled!\n");
       return;
     }
-    GC_generate_random_backtrace_no_gc();
+
+    /* Generate/print a backtrace from a random heap address.   */
+    LOCK();
+    current = GC_generate_random_valid_address();
+    UNLOCK();
+    GC_printf("\n****Chosen address %p in object\n", current);
+    GC_print_backtrace(current);
   }
 
 #endif /* KEEP_BACK_PTRS */
diff --git a/finalize.c b/finalize.c
index 53b1beb6..65ee2701 100644
--- a/finalize.c
+++ b/finalize.c
@@ -1303,8 +1303,11 @@ GC_INNER void GC_notify_or_invoke_finalizers(void)
               /* which may cause occasional mysterious results.         */
               /* We need to release the GC lock, since GC_print_callers */
               /* acquires it.  It probably shouldn't.                   */
+              void *current = GC_generate_random_valid_address();
+
               UNLOCK();
-              GC_generate_random_backtrace_no_gc();
+              GC_printf("\n****Chosen address %p in object\n", current);
+              GC_print_backtrace(current);
               LOCK();
           }
           last_back_trace_gc_no = GC_gc_no;
diff --git a/include/private/gc_priv.h b/include/private/gc_priv.h
index 74e6c8c9..7b6155ae 100644
--- a/include/private/gc_priv.h
+++ b/include/private/gc_priv.h
@@ -2355,7 +2355,6 @@ GC_EXTERN GC_bool GC_have_errors; /* We saw a smashed or leaked object. */
 
 #ifdef KEEP_BACK_PTRS
   GC_EXTERN long GC_backtraces;
-  GC_INNER void GC_generate_random_backtrace_no_gc(void);
 #endif
 
 #if defined(THREADS) || defined(LINT2)