From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: davem@davemloft.net, gregkh@linuxfoundation.org,
Dave Ertman <david.m.ertman@intel.com>,
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 <kiran.patil@intel.com>,
Andrew Bowers <andrewx.bowers@intel.com>
Subject: Re: [net-next 1/9] Implementation of Virtual Bus
Date: Fri, 17 Apr 2020 16:51:48 -0300 [thread overview]
Message-ID: <20200417195148.GL26002@ziepe.ca> (raw)
In-Reply-To: <20200417171034.1533253-2-jeffrey.t.kirsher@intel.com>
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 <linux/device.h>
> +
> +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
next prev parent reply other threads:[~2020-04-17 19:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-17 17:10 [net-next 0/9][pull request] 100GbE Intel Wired LAN Driver Updates 2020-04-17 Jeff Kirsher
2020-04-17 17:10 ` [net-next 1/9] Implementation of Virtual Bus Jeff Kirsher
2020-04-17 19:14 ` Pierre-Louis Bossart
2020-04-17 19:51 ` Jason Gunthorpe [this message]
2020-04-20 23:16 ` Ertman, David M
2020-04-21 0:44 ` Jason Gunthorpe
2020-04-21 23:27 ` Ertman, David M
2020-04-18 12:50 ` Greg KH
2020-04-20 22:59 ` Ertman, David M
2020-04-21 6:52 ` Greg KH
2020-04-20 23:46 ` Ranjani Sridharan
2020-04-17 17:10 ` [net-next 2/9] ice: Create and register virtual bus for RDMA Jeff Kirsher
2020-04-17 19:17 ` Jason Gunthorpe
2020-04-20 23:47 ` Kirsher, Jeffrey T
2020-04-17 23:49 ` Jason Gunthorpe
2020-04-17 17:10 ` [net-next 3/9] ice: Complete RDMA peer registration Jeff Kirsher
2020-04-17 17:10 ` [net-next 4/9] ice: Support resource allocation requests Jeff Kirsher
2020-04-17 17:10 ` [net-next 5/9] ice: Enable event notifications Jeff Kirsher
2020-04-17 17:10 ` [net-next 6/9] ice: Allow reset operations Jeff Kirsher
2020-04-17 17:10 ` [net-next 7/9] ice: Pass through communications to VF Jeff Kirsher
2020-04-17 17:10 ` [net-next 8/9] i40e: Move client header location Jeff Kirsher
2020-04-17 17:10 ` [net-next 9/9] i40e: Register a virtbus device to provide RDMA Jeff Kirsher
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