From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarod Wilson Subject: Re: [patch net-next v2 1/9] Introduce devlink infrastructure Date: Tue, 23 Feb 2016 16:19:48 -0500 Message-ID: <20160223211948.GT38500@redhat.com> References: <1456242694-29463-1-git-send-email-jiri@resnulli.us> <1456242694-29463-2-git-send-email-jiri@resnulli.us> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, davem@davemloft.net, idosch@mellanox.com, eladr@mellanox.com, yotamg@mellanox.com, ogerlitz@mellanox.com, yishaih@mellanox.com, dledford@redhat.com, sean.hefty@intel.com, hal.rosenstock@gmail.com, eugenia@mellanox.com, roopa@cumulusnetworks.com, nikolay@cumulusnetworks.com, hadarh@mellanox.com, jhs@mojatatu.com, john.fastabend@gmail.com, jeffrey.t.kirsher@intel.com, brouer@redhat.com, ivecera@redhat.com, rami.rosen@intel.com, hannes@stressinduktion.org, gospo@cumulusnetworks.com To: Jiri Pirko Return-path: Received: from mx1.redhat.com ([209.132.183.28]:49152 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754895AbcBWVTv (ORCPT ); Tue, 23 Feb 2016 16:19:51 -0500 Content-Disposition: inline In-Reply-To: <1456242694-29463-2-git-send-email-jiri@resnulli.us> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Feb 23, 2016 at 04:51:26PM +0100, Jiri Pirko wrote: > From: Jiri Pirko > > Introduce devlink infrastructure for drivers to register and expose to > userspace via generic Netlink interface. > > There are two basic objects defined: > devlink - one instance for every "parent device", for example switch ASIC > devlink port - one instance for every physical port of the device. > > This initial portion implements basic get/dump of objects to userspace. > Also, port splitter and port type setting is implemented. ... > +/** > + * devlink_alloc - Allocate new devlink instance resources > + * > + * @ops: ops > + * @priv_size: size of user private data > + * > + * Allocate new devlink instance resources, including devlink index > + * and name. > + */ > +struct devlink *devlink_alloc(const struct devlink_ops *ops, size_t priv_size) > +{ > + static atomic_t dev_counter = ATOMIC_INIT(0); > + struct devlink *devlink; > + > + devlink = kzalloc(sizeof(*devlink) + priv_size, GFP_KERNEL); > + if (!devlink) > + return NULL; > + devlink->ops = ops; > + devlink_net_set(devlink, &init_net); > + > +different_name: > + devlink->index = atomic_inc_return(&dev_counter); > + if (devlink->index < 0) { > + /* wrapped */ > + atomic_dec(&dev_counter); > + kfree(devlink); > + return NULL; > + } > + /* atomic_inc_return makes it start at 1, make it start at 0 */ > + devlink->index--; > + > + dev_set_name(&devlink->dev, DEVLINK_GENL_NAME "%d", devlink->index); > + if (devlink_name_exists(devlink_net(devlink), devlink_name(devlink))) > + goto different_name; > + > + INIT_LIST_HEAD(&devlink->port_list); > + device_initialize(&devlink->dev); > + devlink->dev.class = &devlink_class; > + devlink->dev.platform_data = devlink; > + return devlink; > +} > +EXPORT_SYMBOL_GPL(devlink_alloc); The increment then decrement bit feels... Clunky and a little confusing. Why not just atomic_read(&dev_counter) before different_name:, then an atomic_inc_return(&dev_counter) under the if clause before the goto, and eliminate the devlink->index-- bit? -- Jarod Wilson jarod@redhat.com