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From: Greg KH <gregkh@linuxfoundation.org>
To: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: davem@davemloft.net, Dave Ertman <david.m.ertman@intel.com>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	nhorman@redhat.com, sassmann@redhat.com, jgg@ziepe.ca,
	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, Kiran Patil <kiran.patil@intel.com>,
	Andrew Bowers <andrewx.bowers@intel.com>
Subject: Re: [RFC PATCH v4 01/25] virtual-bus: Implementation of Virtual Bus
Date: Fri, 14 Feb 2020 09:02:40 -0800
Message-ID: <20200214170240.GA4034785@kroah.com> (raw)
In-Reply-To: <20200212191424.1715577-2-jeffrey.t.kirsher@intel.com>

On Wed, Feb 12, 2020 at 11:14:00AM -0800, Jeff Kirsher wrote:
> From: Dave Ertman <david.m.ertman@intel.com>
> 
> This is the initial implementation of the Virtual Bus,
> virtbus_device and virtbus_driver.  The virtual bus is
> a software based bus intended to support registering
> virtbus_devices and virtbus_drivers and provide matching
> between them and probing of the registered drivers.
> 
> The bus will support probe/remove shutdown and
> suspend/resume callbacks.
> 
> Kconfig and Makefile alterations are included
> 
> Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
> Signed-off-by: Kiran Patil <kiran.patil@intel.com>
> Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

This looks a lot better, and is more of what I was thinking.  Some minor
comments below:

> +/**
> + * virtbus_dev_register - add a virtual bus device
> + * @vdev: virtual bus device to add
> + */
> +int virtbus_dev_register(struct virtbus_device *vdev)
> +{
> +	int ret;
> +
> +	if (!vdev->release) {
> +		dev_err(&vdev->dev, "virtbus_device .release callback NULL\n");

"virtbus_device MUST have a .release callback that does something!\n" 

> +		return -EINVAL;
> +	}
> +
> +	device_initialize(&vdev->dev);
> +
> +	vdev->dev.bus = &virtual_bus_type;
> +	vdev->dev.release = virtbus_dev_release;
> +	/* 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");
> +		put_device(&vdev->dev);

If you allocate the number before device_initialize(), no need to call
put_device().  Just a minor thing, no big deal.

> +		return ret;
> +	}
> +
> +	vdev->id = ret;
> +	dev_set_name(&vdev->dev, "%s.%d", vdev->name, vdev->id);
> +
> +	dev_dbg(&vdev->dev, "Registering virtbus device '%s'\n",
> +		dev_name(&vdev->dev));
> +
> +	ret = device_add(&vdev->dev);
> +	if (ret)
> +		goto device_add_err;
> +
> +	return 0;
> +
> +device_add_err:
> +	dev_err(&vdev->dev, "Add device to virtbus failed!\n");

Print the return error here too?

> +	put_device(&vdev->dev);
> +	ida_simple_remove(&virtbus_dev_ida, vdev->id);

You need to do this before put_device().

> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(virtbus_dev_register);
> +


> --- /dev/null
> +++ b/include/linux/virtual_bus.h
> @@ -0,0 +1,57 @@
> +/* 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;
> +	const struct virtbus_dev_id *matched_element;
> +};

Any reason you need to make "struct virtbus_device" a public structure
at all?  Why not just make it private and have the release function
pointer be passed as part of the register function?  That will keep
people from poking around in here.

> +
> +/* The memory for the table is expected to remain allocated for the duration
> + * of the pairing between driver and device.  The pointer for the matching
> + * element will be copied to the matched_element field of the virtbus_device.

I don't understand this last sentance, what are you trying to say?  We
save off a pointer to the element, so it better not go away, is that
what you mean?  Why would this happen?

> + */
> +struct virtbus_driver {
> +	int (*probe)(struct virtbus_device *);
> +	int (*remove)(struct virtbus_device *);
> +	void (*shutdown)(struct virtbus_device *);
> +	int (*suspend)(struct virtbus_device *, pm_message_t);
> +	int (*resume)(struct virtbus_device *);

Can all of these be const pointers such that we will not change them?

> +	struct device_driver driver;
> +	const struct virtbus_dev_id *id_table;
> +};

thanks,

greg k-h

  reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 19:13 [RFC PATCH v4 00/25] Intel Wired LAN/RDMA Driver Updates 2020-02-11 Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 01/25] virtual-bus: Implementation of Virtual Bus Jeff Kirsher
2020-02-14 17:02   ` Greg KH [this message]
2020-02-14 20:34     ` Jason Gunthorpe
2020-02-14 20:43       ` Greg KH
2020-02-15  0:01         ` Jason Gunthorpe
2020-02-15  0:53           ` Greg KH
2020-02-14 20:45       ` Greg KH
2020-02-20 18:55         ` Ertman, David M
2020-02-20 19:27           ` Jason Gunthorpe
2020-02-14 21:22   ` Parav Pandit
2020-02-15  0:08   ` Jason Gunthorpe
2020-02-12 19:14 ` [RFC PATCH v4 02/25] ice: Create and register virtual bus for RDMA Jeff Kirsher
2020-02-14 20:39   ` Jason Gunthorpe
2020-02-20 18:48     ` Ertman, David M
2020-02-20 20:58       ` Jason Gunthorpe
2020-02-12 19:14 ` [RFC PATCH v4 03/25] ice: Complete RDMA peer registration Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 04/25] ice: Support resource allocation requests Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 05/25] ice: Enable event notifications Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 06/25] ice: Allow reset operations Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 07/25] ice: Pass through communications to VF Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 08/25] i40e: Move client header location Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 09/25] i40e: Register a virtbus device to provide RDMA Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 10/25] RDMA/irdma: Add driver framework definitions Jeff Kirsher
2020-02-14 22:13   ` Parav Pandit
2020-02-18 20:42     ` Saleem, Shiraz
2020-02-20 22:24       ` Parav Pandit
2020-02-20 23:06         ` Jason Gunthorpe
2020-02-21 17:01         ` Saleem, Shiraz
2020-02-21 17:23           ` Parav Pandit
2020-02-21 18:04             ` Jason Gunthorpe
2020-02-12 19:14 ` [RFC PATCH v4 11/25] RDMA/irdma: Implement device initialization definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 12/25] RDMA/irdma: Implement HW Admin Queue OPs Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 13/25] RDMA/irdma: Add HMC backing store setup functions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 14/25] RDMA/irdma: Add privileged UDA queue implementation Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 15/25] RDMA/irdma: Add QoS definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 16/25] RDMA/irdma: Add connection manager Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 17/25] RDMA/irdma: Add PBLE resource manager Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 18/25] RDMA/irdma: Implement device supported verb APIs Jeff Kirsher
2020-02-14 14:54   ` Jason Gunthorpe
2020-02-14 15:49     ` Andrew Boyer
2020-02-14 16:45       ` Jason Gunthorpe
2020-02-18 20:43     ` Saleem, Shiraz
2020-02-12 19:14 ` [RFC PATCH v4 19/25] RDMA/irdma: Add RoCEv2 UD OP support Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 20/25] RDMA/irdma: Add user/kernel shared libraries Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 21/25] RDMA/irdma: Add miscellaneous utility definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 22/25] RDMA/irdma: Add dynamic tracing for CM Jeff Kirsher
2020-02-14 14:53   ` Jason Gunthorpe
2020-02-18 20:43     ` Saleem, Shiraz
2020-02-12 19:14 ` [RFC PATCH v4 23/25] RDMA/irdma: Add ABI definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 24/25] RDMA: Add irdma Kconfig/Makefile and remove i40iw Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 25/25] RDMA/irdma: Update MAINTAINERS file Jeff Kirsher

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