From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:57011) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S0Fqa-0007Se-1q for qemu-devel@nongnu.org; Wed, 22 Feb 2012 12:19:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S0FqQ-0000mQ-Hd for qemu-devel@nongnu.org; Wed, 22 Feb 2012 12:19:20 -0500 Received: from relay1.mentorg.com ([192.94.38.131]:36701) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S0FqQ-0000mD-5H for qemu-devel@nongnu.org; Wed, 22 Feb 2012 12:19:10 -0500 Message-ID: <4F4523A5.9070908@mentor.com> Date: Wed, 22 Feb 2012 19:19:33 +0200 From: Alexander Barabash MIME-Version: 1.0 References: <1329930831-26837-1-git-send-email-alexander_barabash@mentor.com> <4F45231E.2030600@redhat.com> In-Reply-To: <4F45231E.2030600@redhat.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] qom: In function object_set_link_property(), first call object_ref(), then object_unref(). List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: qemu-devel@nongnu.org On 02/22/2012 07:17 PM, Paolo Bonzini wrote: > On 02/22/2012 06:13 PM, alexander_barabash@mentor.com wrote: >> From: Alexander Barabash >> >> In the old implementation, if the new value of the property links >> to the same object, as the old value, that object is first unref-ed, >> and then ref-ed. This leads to unintended deinitialization of that object. >> >> In the new implementation, this is fixed. >> >> Signed-off-by: Alexander Barabash >> --- >> qom/object.c | 18 +++++++++++++----- >> 1 files changed, 13 insertions(+), 5 deletions(-) >> >> diff --git a/qom/object.c b/qom/object.c >> index 941c291..d1b3ac7 100644 >> --- a/qom/object.c >> +++ b/qom/object.c >> @@ -892,19 +892,19 @@ static void object_set_link_property(Object *obj, Visitor *v, void *opaque, >> const char *name, Error **errp) >> { >> Object **child = opaque; >> + Object *old_target; >> bool ambiguous = false; >> const char *type; >> char *path; >> gchar *target_type; >> + bool clear_old_target = true; >> >> type = object_property_get_type(obj, name, NULL); >> >> visit_type_str(v,&path, name, errp); >> >> - if (*child) { >> - object_unref(*child); >> - *child = NULL; >> - } >> + old_target = *child; >> + *child = NULL; > You can just remove the unref here... > >> if (strcmp(path, "") != 0) { >> Object *target; >> @@ -916,7 +916,11 @@ static void object_set_link_property(Object *obj, Visitor *v, void *opaque, >> if (ambiguous) { >> error_set(errp, QERR_AMBIGUOUS_PATH, path); >> } else if (target) { >> - object_ref(target); >> + if (target != old_target) { >> + object_ref(target); > ... leave the unconditional ref to target here... > >> + } else { >> + clear_old_target = false; >> + } >> *child = target; >> } else { >> target = object_resolve_path(path,&ambiguous); >> @@ -930,6 +934,10 @@ static void object_set_link_property(Object *obj, Visitor *v, void *opaque, >> } >> >> g_free(path); >> + >> + if (clear_old_target&& (old_target != NULL)) { >> + object_unref(old_target); > ... and leave this unref on old_target, without the need for > clear_old_target. > >> + } >> } >> >> void object_property_add_link(Object *obj, const char *name, > Paolo Agreed. Alex