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[2001:4830:134:3::11]) by mx.google.com with ESMTPS id b17-v6si2494089qvk.127.2018.07.12.10.02.24 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 12 Jul 2018 10:02:24 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) client-ip=2001:4830:134:3::11; Authentication-Results: mx.google.com; spf=pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) smtp.mailfrom="qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([::1]:33166 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fdez1-0003qh-Sj for alex.bennee@linaro.org; Thu, 12 Jul 2018 13:02:23 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38705) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fdeyq-0003o3-IY for qemu-arm@nongnu.org; Thu, 12 Jul 2018 13:02:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fdeym-0007x0-C6 for qemu-arm@nongnu.org; Thu, 12 Jul 2018 13:02:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37954) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fdeym-0007w9-2j; Thu, 12 Jul 2018 13:02:08 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2536F3150081; Thu, 12 Jul 2018 17:02:07 +0000 (UTC) Received: from localhost (ovpn-116-12.gru2.redhat.com [10.97.116.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id 601CF194AD; Thu, 12 Jul 2018 17:02:06 +0000 (UTC) Date: Thu, 12 Jul 2018 14:02:04 -0300 From: Eduardo Habkost To: Thomas Huth Message-ID: <20180712170204.GE31657@localhost.localdomain> References: <1531409463-3843-1-git-send-email-thuth@redhat.com> <1531409463-3843-2-git-send-email-thuth@redhat.com> <20180712165224.GD31657@localhost.localdomain> <224a0bbb-9dbb-87eb-9e9b-1c82923010b5@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <224a0bbb-9dbb-87eb-9e9b-1c82923010b5@redhat.com> X-Fnord: you can see the fnord User-Agent: Mutt/1.9.2 (2017-12-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 12 Jul 2018 17:02:07 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-arm] [PATCH 1/5] qom/object: Add a new function object_initialize_as_child() X-BeenThere: qemu-arm@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , qemu-arm@nongnu.org, qemu-devel@nongnu.org, Markus Armbruster , Paolo Bonzini Errors-To: qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-arm" X-TUID: Mx6majhJeEKi On Thu, Jul 12, 2018 at 06:55:20PM +0200, Thomas Huth wrote: > On 12.07.2018 18:52, Eduardo Habkost wrote: > > On Thu, Jul 12, 2018 at 05:30:59PM +0200, Thomas Huth wrote: > >> A lot of code is using the object_initialize() function followed by a call to > >> object_property_add_child() to add the newly initialized object as a child of > >> the current object. Both functions increase the reference counter of the new > >> object, but many spots that call these two functions then forget to drop one > >> of the superfluous references. So the newly created object is often not cleaned > >> up correctly when the parent is destroyed. In the worst case, this can cause > >> crashes, e.g. because device objects are not correctly removed from their > >> parent_bus. > >> Since this is a common pattern between many code spots, let's introdcue a > >> new function that takes care of calling all three required initialization > >> functions, first object_initialize(), then object_property_add_child() and > >> finally object_unref(). > >> > >> Signed-off-by: Thomas Huth > >> --- > >> include/qom/object.h | 19 +++++++++++++++++++ > >> qom/object.c | 14 ++++++++++++++ > >> 2 files changed, 33 insertions(+) > >> > >> diff --git a/include/qom/object.h b/include/qom/object.h > >> index f3d2308..c1b254c 100644 > >> --- a/include/qom/object.h > >> +++ b/include/qom/object.h > >> @@ -749,6 +749,25 @@ int object_set_propv(Object *obj, > >> void object_initialize(void *obj, size_t size, const char *typename); > >> > >> /** > >> + * object_initialize_as_child: > >> + * @parentobj: The parent object to add a property to > >> + * @propname: The name of the property > >> + * @childobj: A pointer to the memory to be used for the object. > >> + * @size: The maximum size available at @obj for the object. > >> + * @type: The name of the type of the object to instantiate. > >> + * @errp: If an error occurs, a pointer to an area to store the area > >> + * > >> + * This function will initialize an object. The memory for the object should > >> + * have already been allocated. The object will then be added as child property > >> + * to a parent with object_property_add_child() function. The returned object > >> + * has a reference count of 1, and will be finalized when the last reference is > >> + * dropped. > >> + */ > >> +void object_initialize_as_child(Object *parentobj, const char *propname, > >> + void *childobj, size_t size, const char *type, > >> + Error **errp); > > > > Why did you use void* instead of Object*? > > That's the same what object_initialize() is doing (see above). Otherwise > all the callers have to cast their pointers with OBJECT() first. Why wouldn't the same argument apply to every single function that takes Object* as argument? Why the OBJECT macro exists? -- Eduardo From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38737) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fdeyt-0003pv-9G for qemu-devel@nongnu.org; Thu, 12 Jul 2018 13:02:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fdeyr-00083R-U5 for qemu-devel@nongnu.org; Thu, 12 Jul 2018 13:02:15 -0400 Date: Thu, 12 Jul 2018 14:02:04 -0300 From: Eduardo Habkost Message-ID: <20180712170204.GE31657@localhost.localdomain> References: <1531409463-3843-1-git-send-email-thuth@redhat.com> <1531409463-3843-2-git-send-email-thuth@redhat.com> <20180712165224.GD31657@localhost.localdomain> <224a0bbb-9dbb-87eb-9e9b-1c82923010b5@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <224a0bbb-9dbb-87eb-9e9b-1c82923010b5@redhat.com> Subject: Re: [Qemu-devel] [PATCH 1/5] qom/object: Add a new function object_initialize_as_child() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth Cc: qemu-devel@nongnu.org, Peter Maydell , Paolo Bonzini , qemu-arm@nongnu.org, Markus Armbruster On Thu, Jul 12, 2018 at 06:55:20PM +0200, Thomas Huth wrote: > On 12.07.2018 18:52, Eduardo Habkost wrote: > > On Thu, Jul 12, 2018 at 05:30:59PM +0200, Thomas Huth wrote: > >> A lot of code is using the object_initialize() function followed by a call to > >> object_property_add_child() to add the newly initialized object as a child of > >> the current object. Both functions increase the reference counter of the new > >> object, but many spots that call these two functions then forget to drop one > >> of the superfluous references. So the newly created object is often not cleaned > >> up correctly when the parent is destroyed. In the worst case, this can cause > >> crashes, e.g. because device objects are not correctly removed from their > >> parent_bus. > >> Since this is a common pattern between many code spots, let's introdcue a > >> new function that takes care of calling all three required initialization > >> functions, first object_initialize(), then object_property_add_child() and > >> finally object_unref(). > >> > >> Signed-off-by: Thomas Huth > >> --- > >> include/qom/object.h | 19 +++++++++++++++++++ > >> qom/object.c | 14 ++++++++++++++ > >> 2 files changed, 33 insertions(+) > >> > >> diff --git a/include/qom/object.h b/include/qom/object.h > >> index f3d2308..c1b254c 100644 > >> --- a/include/qom/object.h > >> +++ b/include/qom/object.h > >> @@ -749,6 +749,25 @@ int object_set_propv(Object *obj, > >> void object_initialize(void *obj, size_t size, const char *typename); > >> > >> /** > >> + * object_initialize_as_child: > >> + * @parentobj: The parent object to add a property to > >> + * @propname: The name of the property > >> + * @childobj: A pointer to the memory to be used for the object. > >> + * @size: The maximum size available at @obj for the object. > >> + * @type: The name of the type of the object to instantiate. > >> + * @errp: If an error occurs, a pointer to an area to store the area > >> + * > >> + * This function will initialize an object. The memory for the object should > >> + * have already been allocated. The object will then be added as child property > >> + * to a parent with object_property_add_child() function. The returned object > >> + * has a reference count of 1, and will be finalized when the last reference is > >> + * dropped. > >> + */ > >> +void object_initialize_as_child(Object *parentobj, const char *propname, > >> + void *childobj, size_t size, const char *type, > >> + Error **errp); > > > > Why did you use void* instead of Object*? > > That's the same what object_initialize() is doing (see above). Otherwise > all the callers have to cast their pointers with OBJECT() first. Why wouldn't the same argument apply to every single function that takes Object* as argument? Why the OBJECT macro exists? -- Eduardo