From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gdb-return-41271-listarch-gdb=sources.redhat.com@sourceware.org>
Received: (qmail 11581 invoked by alias); 27 Aug 2012 16:36:24 -0000
Received: (qmail 11436 invoked by uid 22791); 27 Aug 2012 16:36:20 -0000
X-SWARE-Spam-Status: No, hits=-6.6 required=5.0	tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,RP_MATCHES_RCVD,SPF_HELO_PASS,TW_BJ
X-Spam-Check-By: sourceware.org
Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 27 Aug 2012 16:36:07 +0000
Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24])	by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q7RGa6uJ001116	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK);	Mon, 27 Aug 2012 12:36:06 -0400
Received: from barimba (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1])	by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q7RGa53v028101	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO);	Mon, 27 Aug 2012 12:36:06 -0400
From: Tom Tromey <tromey@redhat.com>
To: Kevin Pouget <kevin.pouget@gmail.com>
Cc: gdb@sourceware.org
Subject: Re: GDB crashing because of Python
References: <CAPftXUJgcra=_exQY3po2AG7KjLSxm9dxkzu=Bsh2zO0eE1Ymw@mail.gmail.com>	<87k3wpr9uy.fsf@fleche.redhat.com>	<CAPftXULyovO08rghxQa2hO4RO8ssK6nt=O0g_abNUDo0OhPTCA@mail.gmail.com>	<87sjbdo2z4.fsf@fleche.redhat.com>	<CAPftXUKCVRbBQ1FH0y48mT1Y4Ze6hLJw8G2RM6cTFZV7o+6ogQ@mail.gmail.com>
Date: Mon, 27 Aug 2012 16:36:00 -0000
In-Reply-To: <CAPftXUKCVRbBQ1FH0y48mT1Y4Ze6hLJw8G2RM6cTFZV7o+6ogQ@mail.gmail.com>	(Kevin Pouget's message of "Mon, 27 Aug 2012 18:04:38 +0200")
Message-ID: <87wr0kgumi.fsf@fleche.redhat.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
Mailing-List: contact gdb-help@sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <gdb.sourceware.org>
List-Subscribe: <mailto:gdb-subscribe@sourceware.org>
List-Archive: <http://sourceware.org/ml/gdb/>
List-Post: <mailto:gdb@sourceware.org>
List-Help: <mailto:gdb-help@sourceware.org>, <http://sourceware.org/ml/#faqs>
Sender: gdb-owner@sourceware.org
X-SW-Source: 2012-08/txt/msg00088.txt.bz2

>>>>> "Kevin" == Kevin Pouget <kevin.pouget@gmail.com> writes:

Kevin> so based on `git bisect`, it looks like the errors were introduced by
Kevin> this commit:

Can you please try the appended patch?

I think the bug here is that this code assumes that
objfile_to_objfile_object returns a new reference, but in fact it does
not.

While looking at this I think I found even more reference counting bugs.
Despair.

Tom

diff --git a/gdb/python/py-newobjfileevent.c b/gdb/python/py-newobjfileevent.c
index 3059ae4..d014be6 100644
--- a/gdb/python/py-newobjfileevent.c
+++ b/gdb/python/py-newobjfileevent.c
@@ -25,7 +25,7 @@ static PyObject *
 create_new_objfile_event_object (struct objfile *objfile)
 {
   PyObject *objfile_event;
-  PyObject *py_objfile = NULL;
+  PyObject *py_objfile;
 
   objfile_event = create_event_object (&new_objfile_event_object_type);
   if (!objfile_event)
@@ -36,12 +36,10 @@ create_new_objfile_event_object (struct objfile *objfile)
                                          "new_objfile",
                                          py_objfile) < 0)
     goto fail;
-  Py_DECREF (py_objfile);
 
   return objfile_event;
 
  fail:
-  Py_XDECREF (py_objfile);
   Py_XDECREF (objfile_event);
   return NULL;
 }