From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 80BC5E6FE41 for ; Fri, 22 Sep 2023 15:07:21 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qjhjM-0002e0-4t; Fri, 22 Sep 2023 11:06:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qjhjJ-0002bg-L7 for qemu-devel@nongnu.org; Fri, 22 Sep 2023 11:06:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qjhjG-0003aK-Qr for qemu-devel@nongnu.org; Fri, 22 Sep 2023 11:06:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695395162; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=4Kvdlkd8vtIAUWdNgbf0UdrkWWv61DlZBkhZ/U7ZjLU=; b=MJ2ZlABkYJ5sPencMHMJKWcncRKVS5LBa8aT7I4HA/7wxOnKbuopV4NWTbqihQMTEO4ACx dUYkoWPwKIr69j6mTG8cRbWeKGqyG0ugk4FJO2dNAWN6InA0mRiLngs62mlcWOspxUJ82W 8fmLHNjjeAaAx8eEfjRZbthpcVtEbIw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-620-E_HakSLXNrSz3iMVUjv_Gg-1; Fri, 22 Sep 2023 11:05:58 -0400 X-MC-Unique: E_HakSLXNrSz3iMVUjv_Gg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7D0A1101A53B; Fri, 22 Sep 2023 15:05:58 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.25]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 231242156701; Fri, 22 Sep 2023 15:05:58 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 16C3B21E6900; Fri, 22 Sep 2023 17:05:57 +0200 (CEST) From: Markus Armbruster To: Kevin Wolf Cc: qemu-devel@nongnu.org, berrange@redhat.com, peter.maydell@linaro.org, pbonzini@redhat.com Subject: Re: [PATCH 11/11] qdev: Rework array properties based on list visitor References: <20230908143703.172758-1-kwolf@redhat.com> <20230908143703.172758-12-kwolf@redhat.com> Date: Fri, 22 Sep 2023 17:05:57 +0200 In-Reply-To: <20230908143703.172758-12-kwolf@redhat.com> (Kevin Wolf's message of "Fri, 8 Sep 2023 16:37:02 +0200") Message-ID: <874jjms0x6.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Kevin Wolf writes: > Until now, array properties are actually implemented with a hack that > uses multiple properties on the QOM level: a static "foo-len" property > and after it is set, dynamically created "foo[i]" properties. > > In external interfaces (-device on the command line and device_add in > QMP), this interface was broken by commit f3558b1b ('qdev: Base object > creation on QDict rather than QemuOpts') because QDicts are unordered > and therefore it could happen that QEMU tried to set the indexed > properties before setting the length, which fails and effectively makes > array properties inaccessible. In particular, this affects the 'ports' > property of the 'rocker' device. > > This patch reworks the external interface so that instead of using a > separate top-level property for the length and for each element, we use > a single true array property that accepts a list value. In the external > interfaces, this is naturally expressed as a JSON list and makes array > properties accessible again. > > Creating an array property on the command line without using JSON format > is currently not possible. This could be fixed by switching from > QemuOpts to a keyval parser, which however requires consideration of the > compatibility implications. > > All internal users of devices with array properties go through > qdev_prop_set_array() at this point, so updating it takes care of all of > them. > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1090 > Fixes: f3558b1b763683bb877f7dd5b282469cdadc65c3 > Signed-off-by: Kevin Wolf > --- > include/hw/qdev-properties.h | 23 ++-- > hw/core/qdev-properties-system.c | 2 +- > hw/core/qdev-properties.c | 204 +++++++++++++++++++------------ > 3 files changed, 133 insertions(+), 96 deletions(-) > > diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h > index 7fa2fdb7c9..9370b36b72 100644 > --- a/include/hw/qdev-properties.h > +++ b/include/hw/qdev-properties.h > @@ -61,7 +61,7 @@ extern const PropertyInfo qdev_prop_size; > extern const PropertyInfo qdev_prop_string; > extern const PropertyInfo qdev_prop_on_off_auto; > extern const PropertyInfo qdev_prop_size32; > -extern const PropertyInfo qdev_prop_arraylen; > +extern const PropertyInfo qdev_prop_array; > extern const PropertyInfo qdev_prop_link; > > #define DEFINE_PROP(_name, _state, _field, _prop, _type, ...) { \ > @@ -115,8 +115,6 @@ extern const PropertyInfo qdev_prop_link; > .bitmask = (_bitmask), \ > .set_default = false) > > -#define PROP_ARRAY_LEN_PREFIX "len-" > - > /** > * DEFINE_PROP_ARRAY: > * @_name: name of the array > @@ -127,24 +125,21 @@ extern const PropertyInfo qdev_prop_link; > * @_arrayprop: PropertyInfo defining what property the array elements have > * @_arraytype: C type of the array elements > * > - * Define device properties for a variable-length array _name. A > - * static property "len-arrayname" is defined. When the device creator > - * sets this property to the desired length of array, further dynamic > - * properties "arrayname[0]", "arrayname[1]", ... are defined so the > - * device creator can set the array element values. Setting the > - * "len-arrayname" property more than once is an error. > + * Define device properties for a variable-length array _name. The array is Please wrap comments around column 70. More of the same below, not noted again. > + * represented as a list in the visitor interface. > + * > + * @_arraytype is required to be movable with memcpy(). > * > - * When the array length is set, the @_field member of the device > + * When the array property is set, the @_field member of the device > * struct is set to the array length, and @_arrayfield is set to point > - * to (zero-initialised) memory allocated for the array. For a zero > - * length array, @_field will be set to 0 and @_arrayfield to NULL. > + * to the memory allocated for the array. Worth mentioning that the @field member must be uint32_t? > + * > * It is the responsibility of the device deinit code to free the > * @_arrayfield memory. > */ > #define DEFINE_PROP_ARRAY(_name, _state, _field, \ > _arrayfield, _arrayprop, _arraytype) \ > - DEFINE_PROP((PROP_ARRAY_LEN_PREFIX _name), \ > - _state, _field, qdev_prop_arraylen, uint32_t, \ > + DEFINE_PROP(_name, _state, _field, qdev_prop_array, uint32_t, \ > .set_default = true, \ > .defval.u = 0, \ > .arrayinfo = &(_arrayprop), \ The backslashes are no longer aligned. > diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c > index 6d5d43eda2..f557ee886e 100644 > --- a/hw/core/qdev-properties-system.c > +++ b/hw/core/qdev-properties-system.c > @@ -450,7 +450,7 @@ static void set_netdev(Object *obj, Visitor *v, const char *name, > peers_ptr->queues = queues; > > out: > - error_set_from_qdev_prop_error(errp, err, obj, name, str); > + error_set_from_qdev_prop_error(errp, err, obj, prop->name, str); > g_free(str); > } > Intentional? > diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c > index 950ef48e01..b2303a6fbc 100644 > --- a/hw/core/qdev-properties.c > +++ b/hw/core/qdev-properties.c > @@ -546,98 +546,152 @@ const PropertyInfo qdev_prop_size32 = { > > /* --- support for array properties --- */ > > -/* Used as an opaque for the object properties we add for each > - * array element. Note that the struct Property must be first > - * in the struct so that a pointer to this works as the opaque > - * for the underlying element's property hooks as well as for > - * our own release callback. > - */ > -typedef struct { > - struct Property prop; > - char *propname; > - ObjectPropertyRelease *release; > -} ArrayElementProperty; > - > -/* object property release callback for array element properties: > - * we call the underlying element's property release hook, and > - * then free the memory we allocated when we added the property. > +static Property array_elem_prop(Object *obj, Property *parent_prop, > + const char *name, char *elem) @parent_prop is an array property. It's backed by an uint32_t length and an element array. @elem points into the element array. Correct? > +{ > + return (Property) { > + .info = parent_prop->arrayinfo, > + .name = name, > + /* > + * This ugly piece of pointer arithmetic sets up the offset so > + * that when the underlying release hook calls qdev_get_prop_ptr > + * they get the right answer despite the array element not actually > + * being inside the device struct. > + */ > + .offset = elem - (char *) obj, Isn't this is undefined behavior? Delete the space between (char *) and obj. > + }; > +} > + > +/* > + * Object property release callback for array properties: We call the underlying > + * element's property release hook for each element. > + * > + * Note that it is the responsibility of the individual device's deinit to free > + * the array proper. What is a device's "deinit"? Is it the unrealize() method? The instance_finalize() method? > */ > -static void array_element_release(Object *obj, const char *name, void *opaque) > +static void release_prop_array(Object *obj, const char *name, void *opaque) > { > - ArrayElementProperty *p = opaque; > - if (p->release) { > - p->release(obj, name, opaque); > + Property *prop = opaque; > + uint32_t *alenptr = object_field_prop_ptr(obj, prop); > + void **arrayptr = (void *)obj + prop->arrayoffset; I'd call these @plen and @pelts, but that's clearly a matter of taste. > + char *elem = *arrayptr; > + int i; > + > + for (i = 0; i < *alenptr; i++) { > + Property elem_prop = array_elem_prop(obj, prop, name, elem); > + prop->arrayinfo->release(obj, NULL, &elem_prop); > + elem += prop->arrayfieldsize; > } > - g_free(p->propname); > - g_free(p); > } > > -static void set_prop_arraylen(Object *obj, Visitor *v, const char *name, > - void *opaque, Error **errp) > +/* > + * Setter for an array property. This sets both the array length (which is > + * technically the property field in the object) and the array itself (a pointer > + * to which is stored in the additional field described by prop->arrayoffset). > + */ > +static void set_prop_array(Object *obj, Visitor *v, const char *name, > + void *opaque, Error **errp) > { > - /* Setter for the property which defines the length of a > - * variable-sized property array. As well as actually setting the > - * array-length field in the device struct, we have to create the > - * array itself and dynamically add the corresponding properties. > - */ > + ERRP_GUARD(); > + Drop the blank line. > Property *prop = opaque; > uint32_t *alenptr = object_field_prop_ptr(obj, prop); > void **arrayptr = (void *)obj + prop->arrayoffset; > - void *eltptr; > - const char *arrayname; > - int i; > + GenericList *list, *elem, *next; > + const size_t list_elem_size = sizeof(*list) + prop->arrayfieldsize; This can be smaller than the size of the QAPI-generated list type, since the compiler may add padding. Does it matter? > + char *elemptr; > + bool ok = true; > > if (*alenptr) { > error_setg(errp, "array size property %s may not be set more than once", > name); > return; > } > - if (!visit_type_uint32(v, name, alenptr, errp)) { > + > + if (!visit_start_list(v, name, &list, list_elem_size, errp)) { > return; > } > - if (!*alenptr) { > + > + /* Read the whole input into a temporary list */ > + elem = list; > + while (elem) { > + Property elem_prop = array_elem_prop(obj, prop, name, elem->padding); > + prop->arrayinfo->set(obj, v, NULL, &elem_prop, errp); > + if (*errp) { > + ok = false; > + goto out_obj; > + } > + (*alenptr)++; > + elem = visit_next_list(v, elem, list_elem_size); > + } > + > + ok = visit_check_list(v, errp); > +out_obj: > + visit_end_list(v, (void**) &list); > + > + if (!ok) { > + for (elem = list; elem; elem = next) { > + next = elem->next; > + g_free(elem); > + } We consume the list even on error. It's too late in my day for me to see why that's proper. > return; > } > > - /* DEFINE_PROP_ARRAY guarantees that name should start with this prefix; > - * strip it off so we can get the name of the array itself. > + /* > + * Now that we know how big the array has to be, move the data over to a > + * linear array and free the temporary list. > */ > - assert(strncmp(name, PROP_ARRAY_LEN_PREFIX, > - strlen(PROP_ARRAY_LEN_PREFIX)) == 0); > - arrayname = name + strlen(PROP_ARRAY_LEN_PREFIX); > + *arrayptr = g_malloc_n(*alenptr, prop->arrayfieldsize); > + elemptr = *arrayptr; > + for (elem = list; elem; elem = next) { > + memcpy(elemptr, elem->padding, prop->arrayfieldsize); > + elemptr += prop->arrayfieldsize; > + next = elem->next; > + g_free(elem); > + } > +} > > - /* Note that it is the responsibility of the individual device's deinit > - * to free the array proper. > - */ > - *arrayptr = eltptr = g_malloc0(*alenptr * prop->arrayfieldsize); > - for (i = 0; i < *alenptr; i++, eltptr += prop->arrayfieldsize) { > - char *propname = g_strdup_printf("%s[%d]", arrayname, i); > - ArrayElementProperty *arrayprop = g_new0(ArrayElementProperty, 1); > - arrayprop->release = prop->arrayinfo->release; > - arrayprop->propname = propname; > - arrayprop->prop.info = prop->arrayinfo; > - arrayprop->prop.name = propname; > - /* This ugly piece of pointer arithmetic sets up the offset so > - * that when the underlying get/set hooks call qdev_get_prop_ptr > - * they get the right answer despite the array element not actually > - * being inside the device struct. > - */ > - arrayprop->prop.offset = eltptr - (void *)obj; > - assert(object_field_prop_ptr(obj, &arrayprop->prop) == eltptr); > - object_property_add(obj, propname, > - arrayprop->prop.info->name, > - field_prop_getter(arrayprop->prop.info), > - field_prop_setter(arrayprop->prop.info), > - array_element_release, > - arrayprop); > +static void get_prop_array(Object *obj, Visitor *v, const char *name, > + void *opaque, Error **errp) > +{ > + ERRP_GUARD(); > + Drop the blank line. > + Property *prop = opaque; > + uint32_t *alenptr = object_field_prop_ptr(obj, prop); > + void **arrayptr = (void *)obj + prop->arrayoffset; > + char *elem = *arrayptr; > + GenericList *list; > + const size_t list_elem_size = sizeof(*list) + prop->arrayfieldsize; > + int i; > + > + if (!visit_start_list(v, name, &list, list_elem_size, errp)) { > + return; > } > + > + for (i = 0; i < *alenptr; i++) { > + Property elem_prop = array_elem_prop(obj, prop, name, elem); > + prop->arrayinfo->get(obj, v, NULL, &elem_prop, errp); > + if (*errp) { > + goto out_obj; > + } > + elem += prop->arrayfieldsize; > + } > + You neglect to call visit_check_list(). > +out_obj: > + visit_end_list(v, (void**) &list); > } > > -const PropertyInfo qdev_prop_arraylen = { > - .name = "uint32", > - .get = get_uint32, > - .set = set_prop_arraylen, > - .set_default_value = qdev_propinfo_set_default_value_uint, > +static void default_prop_array(ObjectProperty *op, const Property *prop) > +{ > + object_property_set_default_list(op); > +} > + > +const PropertyInfo qdev_prop_array = { > + .name = "list", > + .get = get_prop_array, > + .set = set_prop_array, > + .release = release_prop_array, > + .set_default_value = default_prop_array, > }; > > /* --- public helpers --- */ > @@ -743,20 +797,8 @@ void qdev_prop_set_enum(DeviceState *dev, const char *name, int value) > > void qdev_prop_set_array(DeviceState *dev, const char *name, QList *values) > { > - const QListEntry *entry; > - g_autofree char *prop_len = g_strdup_printf("len-%s", name); > - uint32_t i = 0; > - > - object_property_set_int(OBJECT(dev), prop_len, qlist_size(values), > - &error_abort); > - > - QLIST_FOREACH_ENTRY(values, entry) { > - g_autofree char *prop_idx = g_strdup_printf("%s[%u]", name, i); > - object_property_set_qobject(OBJECT(dev), prop_idx, entry->value, > - &error_abort); > - i++; > - } > - > + object_property_set_qobject(OBJECT(dev), name, QOBJECT(values), > + &error_abort); > qobject_unref(values); > } I like this very much.