From: Guido van Rossum <guido@python.org>
Date: Thu, 28 Mar 2002 20:41:02 +0000 (+0000)
Subject: Sort-of backport to 2.1.3 (if we ever release it) of the following.
X-Git-Tag: v2.1.3~31
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c44d823daac35b8f1f9a62ae54ae15dc81e03d3c;p=thirdparty%2FPython%2Fcpython.git

Sort-of backport to 2.1.3 (if we ever release it) of the following.
(The fix looks different, but does the same thing to the 2.1 GC code
that Neil's patch does to the 2.2 GC code.)

This is Neil's fix for SF bug 535905 (Evil Trashcan and GC interaction).

The fix makes it possible to call PyObject_GC_UnTrack() more than once
on the same object, and then move the PyObject_GC_UnTrack() call to
*before* the trashcan code is invoked.

BUGFIX CANDIDATE!
---

diff --git a/Modules/gcmodule.c b/Modules/gcmodule.c
index e781bdf9e786..011bb1461a9c 100644
--- a/Modules/gcmodule.c
+++ b/Modules/gcmodule.c
@@ -87,12 +87,14 @@ gc_list_append(PyGC_Head *node, PyGC_Head *list)
 static void
 gc_list_remove(PyGC_Head *node)
 {
+	if (node->gc_next == NULL)
+		return;
 	node->gc_prev->gc_next = node->gc_next;
 	node->gc_next->gc_prev = node->gc_prev;
 #ifdef Py_DEBUG
 	node->gc_prev = NULL;
-	node->gc_next = NULL;
 #endif
+	node->gc_next = NULL;
 }
 
 static void 
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 8ad44c181cd1..bac0edfc2de0 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -619,8 +619,8 @@ dict_dealloc(register dictobject *mp)
 {
 	register int i;
 	register dictentry *ep;
-	Py_TRASHCAN_SAFE_BEGIN(mp)
 	PyObject_GC_Fini(mp);
+	Py_TRASHCAN_SAFE_BEGIN(mp)
 	for (i = 0, ep = mp->ma_table; i < mp->ma_size; i++, ep++) {
 		if (ep->me_key != NULL) {
 			Py_DECREF(ep->me_key);
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 7044edeea4f6..6868504ab323 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -176,8 +176,8 @@ static void
 list_dealloc(PyListObject *op)
 {
 	int i;
-	Py_TRASHCAN_SAFE_BEGIN(op)
 	PyObject_GC_Fini(op);
+	Py_TRASHCAN_SAFE_BEGIN(op)
 	if (op->ob_item != NULL) {
 		/* Do it backwards, for Christian Tismer.
 		   There's a simple test case where somehow this reduces
diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index ca76bb5923ff..000856d5f6f5 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -143,8 +143,8 @@ tupledealloc(register PyTupleObject *op)
 {
 	register int i;
 	register int len =  op->ob_size;
-	Py_TRASHCAN_SAFE_BEGIN(op)
 	PyObject_GC_Fini(op);
+	Py_TRASHCAN_SAFE_BEGIN(op)
 	if (len > 0) {
 		i = len;
 		while (--i >= 0)