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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id v37sm1799562qtc.7.2020.04.17.12.51.49 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Fri, 17 Apr 2020 12:51:49 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jPX1h-00054l-09; Fri, 17 Apr 2020 16:51:49 -0300 Date: Fri, 17 Apr 2020 16:51:48 -0300 From: Jason Gunthorpe To: Jeff Kirsher Cc: davem@davemloft.net, gregkh@linuxfoundation.org, Dave Ertman , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, nhorman@redhat.com, sassmann@redhat.com, parav@mellanox.com, galpress@amazon.com, selvin.xavier@broadcom.com, sriharsha.basavapatna@broadcom.com, benve@cisco.com, bharat@chelsio.com, xavier.huwei@huawei.com, yishaih@mellanox.com, leonro@mellanox.com, mkalderon@marvell.com, aditr@vmware.com, ranjani.sridharan@linux.intel.com, pierre-louis.bossart@linux.intel.com, Kiran Patil , Andrew Bowers Subject: Re: [net-next 1/9] Implementation of Virtual Bus Message-ID: <20200417195148.GL26002@ziepe.ca> References: <20200417171034.1533253-1-jeffrey.t.kirsher@intel.com> <20200417171034.1533253-2-jeffrey.t.kirsher@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200417171034.1533253-2-jeffrey.t.kirsher@intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Apr 17, 2020 at 10:10:26AM -0700, Jeff Kirsher wrote: > +/** > + * virtbus_release_device - Destroy a virtbus device > + * @_dev: device to release > + */ > +static void virtbus_release_device(struct device *_dev) > +{ > + struct virtbus_device *vdev = to_virtbus_dev(_dev); > + > + ida_simple_remove(&virtbus_dev_ida, vdev->id); > + vdev->release(vdev); This order should probably be swapped (store vdev->id on the stack) > +/** > + * virtbus_register_device - add a virtual bus device > + * @vdev: virtual bus device to add > + */ > +int virtbus_register_device(struct virtbus_device *vdev) > +{ > + int ret; > + > + /* Do this first so that all error paths perform a put_device */ > + device_initialize(&vdev->dev); > + > + if (!vdev->release) { > + ret = -EINVAL; > + dev_err(&vdev->dev, "virtbus_device MUST have a .release callback that does something.\n"); > + goto device_pre_err; This does put_device but the release() hasn't been set yet. Doesn't it leak memory? > + } > + > + /* All device IDs are automatically allocated */ > + ret = ida_simple_get(&virtbus_dev_ida, 0, 0, GFP_KERNEL); > + if (ret < 0) { > + dev_err(&vdev->dev, "get IDA idx for virtbus device failed!\n"); > + goto device_pre_err; Do this before device_initialize() > + } > + > + > + vdev->dev.bus = &virtual_bus_type; > + vdev->dev.release = virtbus_release_device; And this immediately after > + > + vdev->id = ret; > + dev_set_name(&vdev->dev, "%s.%d", vdev->name, vdev->id); Missing check of return code Can't understand why vdev->name is being passed in with the struct, why not just a function argument? > + dev_dbg(&vdev->dev, "Registering virtbus device '%s'\n", > + dev_name(&vdev->dev)); > + > + ret = device_add(&vdev->dev); > + if (ret) > + goto device_add_err; This looks like it does ida_simple_remove twice, once in the goto and once from the release function called by put_device. > +/** > + * virtbus_unregister_device - remove a virtual bus device > + * @vdev: virtual bus device we are removing > + */ > +void virtbus_unregister_device(struct virtbus_device *vdev) > +{ > + device_del(&vdev->dev); > + put_device(&vdev->dev); > +} > +EXPORT_SYMBOL_GPL(virtbus_unregister_device); Just inline this as wrapper around device_unregister > +/** > + * __virtbus_register_driver - register a driver for virtual bus devices > + * @vdrv: virtbus_driver structure > + * @owner: owning module/driver > + */ > +int __virtbus_register_driver(struct virtbus_driver *vdrv, struct module *owner) > +{ > + if (!vdrv->probe || !vdrv->remove || !vdrv->shutdown || !vdrv->id_table) > + return -EINVAL; > + > + vdrv->driver.owner = owner; > + vdrv->driver.bus = &virtual_bus_type; > + vdrv->driver.probe = virtbus_probe_driver; > + vdrv->driver.remove = virtbus_remove_driver; > + vdrv->driver.shutdown = virtbus_shutdown_driver; > + vdrv->driver.suspend = virtbus_suspend_driver; > + vdrv->driver.resume = virtbus_resume_driver; > + > + return driver_register(&vdrv->driver); > +} > +EXPORT_SYMBOL_GPL(__virtbus_register_driver); > + > +/** > + * virtbus_unregister_driver - unregister a driver for virtual bus devices > + * @vdrv: virtbus_driver structure > + */ > +void virtbus_unregister_driver(struct virtbus_driver *vdrv) > +{ > + driver_unregister(&vdrv->driver); > +} > +EXPORT_SYMBOL_GPL(virtbus_unregister_driver); Also just inline this > diff --git a/include/linux/virtual_bus.h b/include/linux/virtual_bus.h > new file mode 100644 > index 000000000000..4df06178e72f > +++ b/include/linux/virtual_bus.h > @@ -0,0 +1,53 @@ > +/* SPDX-License-Identifier: GPL-2.0-only */ > +/* > + * virtual_bus.h - lightweight software bus > + * > + * Copyright (c) 2019-20 Intel Corporation > + * > + * Please see Documentation/driver-api/virtual_bus.rst for more information > + */ > + > +#ifndef _VIRTUAL_BUS_H_ > +#define _VIRTUAL_BUS_H_ > + > +#include > + > +struct virtbus_device { > + struct device dev; > + const char *name; > + void (*release)(struct virtbus_device *); > + int id; id can't be negative > +int virtbus_register_device(struct virtbus_device *vdev); > +void virtbus_unregister_device(struct virtbus_device *vdev); I continue to think the alloc/register pattern, eg as demonstrated by vdpa_alloc_device() and vdpa_register_device() is easier for drivers to implement correctly. > +int > +__virtbus_register_driver(struct virtbus_driver *vdrv, struct module *owner); > +void virtbus_unregister_driver(struct virtbus_driver *vdrv); > + > +#define virtbus_register_driver(vdrv) \ > + __virtbus_register_driver(vdrv, THIS_MODULE) > + It is reasonable to also provide a module_driver() macro. Jason