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Tue, 21 Jul 2020 14:35:25 +0000 (UTC) Date: Tue, 21 Jul 2020 15:35:22 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Christophe de Dinechin Subject: Re: [PATCH v5 02/10] object: qom module support Message-ID: <20200721143522.GK843362@redhat.com> References: <20200624131045.14512-1-kraxel@redhat.com> <20200624131045.14512-3-kraxel@redhat.com> <7himeimfnc.fsf@turbo.dinechin.lan> MIME-Version: 1.0 In-Reply-To: <7himeimfnc.fsf@turbo.dinechin.lan> User-Agent: Mutt/1.14.5 (2020-06-23) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/21 10:17:05 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Eduardo Habkost , qemu-devel@nongnu.org, Gerd Hoffmann , Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , philmd@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Jul 20, 2020 at 04:20:55PM +0200, Christophe de Dinechin wrote: > > On 2020-06-24 at 15:10 CEST, Gerd Hoffmann wrote... > > Little helper function to load modules on demand. In most cases adding > > module loading support for devices and other objects is just > > s/object_class_by_name/module_object_class_by_name/ in the right spot. > > > > Signed-off-by: Gerd Hoffmann > > --- > > include/qom/object.h | 12 ++++++++++++ > > qom/object.c | 14 ++++++++++++++ > > 2 files changed, 26 insertions(+) > > > > diff --git a/include/qom/object.h b/include/qom/object.h > > index 94a61ccc3fe8..51f188137f1f 100644 > > --- a/include/qom/object.h > > +++ b/include/qom/object.h > > @@ -994,6 +994,18 @@ bool object_class_is_abstract(ObjectClass *klass); > > */ > > ObjectClass *object_class_by_name(const char *typename); > > > > +/** > > + * module_object_class_by_name: > > + * @typename: The QOM typename to obtain the class for. > > + * > > + * For objects which might be provided by a module. Behaves like > > + * object_class_by_name, but additionally tries to load the module > > + * needed in case the class is not available. > > + * > > + * Returns: The class for @typename or %NULL if not found. > > + */ > > +ObjectClass *module_object_class_by_name(const char *typename); > > + > > void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque), > > const char *implements_type, bool include_abstract, > > void *opaque); > > diff --git a/qom/object.c b/qom/object.c > > index 6ece96bc2bfc..34daaf1280f5 100644 > > --- a/qom/object.c > > +++ b/qom/object.c > > @@ -985,6 +985,20 @@ ObjectClass *object_class_by_name(const char *typename) > > return type->class; > > } > > > > +ObjectClass *module_object_class_by_name(const char *typename) > > +{ > > + ObjectClass *oc; > > + > > + oc = object_class_by_name(typename); > > +#ifdef CONFIG_MODULES > > + if (!oc) { > > + module_load_qom_one(typename); > > + oc = object_class_by_name(typename); > > + } > > +#endif > > I'm wondering if there is any reason to only trigger the module load when > you don't find the object class. You could simply call module_load_qom_one > under #ifdef CONFIG_MODULES. > > Performance wise, I don't think this makes much of a difference, and it > simplifies the logical flow IMO. I wouldn't make that assumption about performance - module_load_qom_one() does alot of work, and there are places where object / class creation is performance critical. We might not happen to trigger them now with the current set of modules, but we can easily do so in future. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|