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* Re: [PATCH 1/1] Staging: hv: mousevsc: Move the mouse driver out of staging
From: Dmitry Torokhov @ 2011-10-23  7:24 UTC (permalink / raw)
  To: K. Y. Srinivasan
  Cc: gregkh, linux-kernel, devel, virtualization, linux-input,
	Haiyang Zhang, Jiri Kosina
In-Reply-To: <1318658907-16698-1-git-send-email-kys@microsoft.com>

Hi K. Y.,

On Fri, Oct 14, 2011 at 11:08:27PM -0700, K. Y. Srinivasan wrote:
> In preparation for moving the mouse driver out of staging, seek community
> review of the mouse driver code.
> 

Because it is a HID driver it should go through Jiri Kosina's tree
(CCed). Still, a few comments below.

> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> ---
>  drivers/hid/Kconfig           |    6 +
>  drivers/hid/Makefile          |    1 +
>  drivers/hid/hv_mouse.c        |  599 +++++++++++++++++++++++++++++++++++++++++
>  drivers/staging/hv/Kconfig    |    6 -
>  drivers/staging/hv/Makefile   |    1 -
>  drivers/staging/hv/hv_mouse.c |  599 -----------------------------------------
>  6 files changed, 606 insertions(+), 606 deletions(-)
>  create mode 100644 drivers/hid/hv_mouse.c
>  delete mode 100644 drivers/staging/hv/hv_mouse.c
> 
> diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
> index 1130a89..f8b98b8 100644
> --- a/drivers/hid/Kconfig
> +++ b/drivers/hid/Kconfig
> @@ -613,6 +613,12 @@ config HID_ZYDACRON
>  	---help---
>  	Support for Zydacron remote control.
>  
> +config HYPERV_MOUSE
> +	tristate "Microsoft Hyper-V mouse driver"
> +	depends on HYPERV
> +	help
> +	  Select this option to enable the Hyper-V mouse driver.
> +
>  endmenu
>  
>  endif # HID_SUPPORT
> diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
> index 0a0a38e..436ac2e 100644
> --- a/drivers/hid/Makefile
> +++ b/drivers/hid/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_HID_ZYDACRON)	+= hid-zydacron.o
>  obj-$(CONFIG_HID_WACOM)		+= hid-wacom.o
>  obj-$(CONFIG_HID_WALTOP)	+= hid-waltop.o
>  obj-$(CONFIG_HID_WIIMOTE)	+= hid-wiimote.o
> +obj-$(CONFIG_HYPERV_MOUSE)	+= hv_mouse.o
>  
>  obj-$(CONFIG_USB_HID)		+= usbhid/
>  obj-$(CONFIG_USB_MOUSE)		+= usbhid/
> diff --git a/drivers/hid/hv_mouse.c b/drivers/hid/hv_mouse.c
> new file mode 100644
> index 0000000..ccd39c7
> --- /dev/null
> +++ b/drivers/hid/hv_mouse.c
> @@ -0,0 +1,599 @@
> +/*
> + *  Copyright (c) 2009, Citrix Systems, Inc.
> + *  Copyright (c) 2010, Microsoft Corporation.
> + *  Copyright (c) 2011, Novell Inc.
> + *
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under the terms and conditions of the GNU General Public License,
> + *  version 2, as published by the Free Software Foundation.
> + *
> + *  This program is distributed in the hope it will be useful, but WITHOUT
> + *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + *  more details.
> + */
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/workqueue.h>

Is this really needed?

> +#include <linux/sched.h>

You probably want completion.h instead.

> +#include <linux/wait.h>
> +#include <linux/input.h>
> +#include <linux/hid.h>
> +#include <linux/hiddev.h>
> +#include <linux/hyperv.h>
> +
> +
> +struct hv_input_dev_info {
> +	unsigned int size;
> +	unsigned short vendor;
> +	unsigned short product;
> +	unsigned short version;
> +	unsigned short reserved[11];
> +};
> +
> +/* The maximum size of a synthetic input message. */
> +#define SYNTHHID_MAX_INPUT_REPORT_SIZE 16
> +
> +/*
> + * Current version
> + *
> + * History:
> + * Beta, RC < 2008/1/22        1,0
> + * RC > 2008/1/22              2,0
> + */
> +#define SYNTHHID_INPUT_VERSION_MAJOR	2
> +#define SYNTHHID_INPUT_VERSION_MINOR	0
> +#define SYNTHHID_INPUT_VERSION		(SYNTHHID_INPUT_VERSION_MINOR | \
> +					 (SYNTHHID_INPUT_VERSION_MAJOR << 16))
> +
> +
> +#pragma pack(push, 1)
> +/*
> + * Message types in the synthetic input protocol
> + */
> +enum synthhid_msg_type {
> +	SYNTH_HID_PROTOCOL_REQUEST,
> +	SYNTH_HID_PROTOCOL_RESPONSE,
> +	SYNTH_HID_INITIAL_DEVICE_INFO,
> +	SYNTH_HID_INITIAL_DEVICE_INFO_ACK,
> +	SYNTH_HID_INPUT_REPORT,
> +	SYNTH_HID_MAX
> +};
> +
> +/*
> + * Basic message structures.
> + */
> +struct synthhid_msg_hdr {
> +	enum synthhid_msg_type type;
> +	u32 size;
> +};
> +
> +struct synthhid_msg {
> +	struct synthhid_msg_hdr header;
> +	char data[1]; /* Enclosed message */
> +};
> +
> +union synthhid_version {
> +	struct {
> +		u16 minor_version;
> +		u16 major_version;
> +	};
> +	u32 version;
> +};
> +
> +/*
> + * Protocol messages
> + */
> +struct synthhid_protocol_request {
> +	struct synthhid_msg_hdr header;
> +	union synthhid_version version_requested;
> +};
> +
> +struct synthhid_protocol_response {
> +	struct synthhid_msg_hdr header;
> +	union synthhid_version version_requested;
> +	unsigned char approved;
> +};
> +
> +struct synthhid_device_info {
> +	struct synthhid_msg_hdr header;
> +	struct hv_input_dev_info hid_dev_info;
> +	struct hid_descriptor hid_descriptor;
> +};
> +
> +struct synthhid_device_info_ack {
> +	struct synthhid_msg_hdr header;
> +	unsigned char reserved;
> +};
> +
> +struct synthhid_input_report {
> +	struct synthhid_msg_hdr header;
> +	char buffer[1];
> +};
> +
> +#pragma pack(pop)
> +
> +#define INPUTVSC_SEND_RING_BUFFER_SIZE		(10*PAGE_SIZE)
> +#define INPUTVSC_RECV_RING_BUFFER_SIZE		(10*PAGE_SIZE)
> +
> +#define NBITS(x) (((x)/BITS_PER_LONG)+1)
> +
> +enum pipe_prot_msg_type {
> +	PIPE_MESSAGE_INVALID,
> +	PIPE_MESSAGE_DATA,
> +	PIPE_MESSAGE_MAXIMUM
> +};
> +
> +
> +struct pipe_prt_msg {
> +	enum pipe_prot_msg_type type;
> +	u32 size;
> +	char data[1];
> +};
> +
> +struct  mousevsc_prt_msg {
> +	enum pipe_prot_msg_type type;
> +	u32 size;
> +	union {
> +		struct synthhid_protocol_request request;
> +		struct synthhid_protocol_response response;
> +		struct synthhid_device_info_ack ack;
> +	};
> +};
> +
> +/*
> + * Represents an mousevsc device
> + */
> +struct mousevsc_dev {
> +	struct hv_device	*device;
> +	unsigned char		init_complete;
> +	struct mousevsc_prt_msg	protocol_req;
> +	struct mousevsc_prt_msg	protocol_resp;
> +	/* Synchronize the request/response if needed */
> +	struct completion	wait_event;
> +	int			dev_info_status;
> +
> +	struct hid_descriptor	*hid_desc;
> +	unsigned char		*report_desc;
> +	u32			report_desc_size;
> +	struct hv_input_dev_info hid_dev_info;
> +	int			connected;

bool?

> +	struct hid_device       *hid_device;
> +};
> +
> +
> +static struct mousevsc_dev *alloc_input_device(struct hv_device *device)
> +{
> +	struct mousevsc_dev *input_dev;
> +
> +	input_dev = kzalloc(sizeof(struct mousevsc_dev), GFP_KERNEL);
> +

This blank line is extra.

> +	if (!input_dev)
> +		return NULL;
> +
> +	input_dev->device = device;
> +	hv_set_drvdata(device, input_dev);
> +	init_completion(&input_dev->wait_event);
> +
> +	return input_dev;
> +}
> +
> +static void free_input_device(struct mousevsc_dev *device)
> +{
> +	kfree(device->hid_desc);
> +	kfree(device->report_desc);
> +	hv_set_drvdata(device->device, NULL);
> +	kfree(device);
> +}
> +
> +
> +static void mousevsc_on_receive_device_info(struct mousevsc_dev *input_device,
> +				struct synthhid_device_info *device_info)
> +{
> +	int ret = 0;
> +	struct hid_descriptor *desc;
> +	struct mousevsc_prt_msg ack;
> +
> +	/* Assume success for now */
> +	input_device->dev_info_status = 0;
> +
> +	memcpy(&input_device->hid_dev_info, &device_info->hid_dev_info,
> +		sizeof(struct hv_input_dev_info));
> +
> +	desc = &device_info->hid_descriptor;
> +	WARN_ON(desc->bLength == 0);
> +
> +	input_device->hid_desc = kzalloc(desc->bLength, GFP_ATOMIC);
> +
> +	if (!input_device->hid_desc)
> +		goto cleanup;
> +
> +	memcpy(input_device->hid_desc, desc, desc->bLength);
> +
> +	input_device->report_desc_size = desc->desc[0].wDescriptorLength;
> +	if (input_device->report_desc_size == 0)
> +		goto cleanup;
> +	input_device->report_desc = kzalloc(input_device->report_desc_size,
> +					  GFP_ATOMIC);
> +
> +	if (!input_device->report_desc)
> +		goto cleanup;
> +
> +	memcpy(input_device->report_desc,
> +	       ((unsigned char *)desc) + desc->bLength,
> +	       desc->desc[0].wDescriptorLength);
> +
> +	/* Send the ack */
> +	memset(&ack, 0, sizeof(struct mousevsc_prt_msg));
> +
> +	ack.type = PIPE_MESSAGE_DATA;
> +	ack.size = sizeof(struct synthhid_device_info_ack);
> +
> +	ack.ack.header.type = SYNTH_HID_INITIAL_DEVICE_INFO_ACK;
> +	ack.ack.header.size = 1;
> +	ack.ack.reserved = 0;

That looks like a constant structure...

> +
> +	ret = vmbus_sendpacket(input_device->device->channel,
> +			&ack,
> +			sizeof(struct pipe_prt_msg) - sizeof(unsigned char) +
> +			sizeof(struct synthhid_device_info_ack),
> +			(unsigned long)&ack,
> +			VM_PKT_DATA_INBAND,
> +			VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> +	if (ret != 0)
> +		goto cleanup;
> +
> +	complete(&input_device->wait_event);
> +
> +	return;
> +
> +cleanup:
> +	kfree(input_device->hid_desc);
> +	input_device->hid_desc = NULL;
> +
> +	kfree(input_device->report_desc);
> +	input_device->report_desc = NULL;
> +
> +	input_device->dev_info_status = -1;
> +	complete(&input_device->wait_event);
> +}
> +
> +static void mousevsc_on_receive(struct hv_device *device,
> +				struct vmpacket_descriptor *packet)
> +{
> +	struct pipe_prt_msg *pipe_msg;
> +	struct synthhid_msg *hid_msg;
> +	struct mousevsc_dev *input_dev = hv_get_drvdata(device);
> +	struct synthhid_input_report *input_report;
> +
> +	pipe_msg = (struct pipe_prt_msg *)((unsigned long)packet +
> +						(packet->offset8 << 3));
> +
> +	if (pipe_msg->type != PIPE_MESSAGE_DATA)
> +		return;
> +
> +	hid_msg = (struct synthhid_msg *)&pipe_msg->data[0];
> +
> +	switch (hid_msg->header.type) {
> +	case SYNTH_HID_PROTOCOL_RESPONSE:
> +		memcpy(&input_dev->protocol_resp, pipe_msg,
> +		       pipe_msg->size + sizeof(struct pipe_prt_msg) -
> +		       sizeof(unsigned char));
> +		complete(&input_dev->wait_event);
> +		break;
> +
> +	case SYNTH_HID_INITIAL_DEVICE_INFO:
> +		WARN_ON(pipe_msg->size < sizeof(struct hv_input_dev_info));
> +
> +		/*
> +		 * Parse out the device info into device attr,
> +		 * hid desc and report desc
> +		 */
> +		mousevsc_on_receive_device_info(input_dev,
> +			(struct synthhid_device_info *)&pipe_msg->data[0]);
> +		break;
> +	case SYNTH_HID_INPUT_REPORT:
> +		input_report =
> +			(struct synthhid_input_report *)&pipe_msg->data[0];
> +		if (!input_dev->init_complete)
> +			break;
> +		hid_input_report(input_dev->hid_device,
> +				HID_INPUT_REPORT, input_report->buffer,
> +				input_report->header.size, 1);
> +		break;
> +	default:
> +		pr_err("unsupported hid msg type - type %d len %d",
> +		       hid_msg->header.type, hid_msg->header.size);
> +		break;
> +	}
> +
> +}
> +
> +static void mousevsc_on_channel_callback(void *context)
> +{
> +	const int packetSize = 0x100;
> +	int ret = 0;
> +	struct hv_device *device = (struct hv_device *)context;

No need to cast.

> +
> +	u32 bytes_recvd;
> +	u64 req_id;
> +	unsigned char packet[0x100];

Hmm, 100 bytes on stack... and are we in interrupt context by any
chance?

> +	struct vmpacket_descriptor *desc;
> +	unsigned char	*buffer = packet;
> +	int	bufferlen = packetSize;
> +
> +
> +	do {
> +		ret = vmbus_recvpacket_raw(device->channel, buffer,
> +					bufferlen, &bytes_recvd, &req_id);
> +
> +		if (ret == 0) {
> +			if (bytes_recvd > 0) {
> +				desc = (struct vmpacket_descriptor *)buffer;
> +
> +				switch (desc->type) {
> +				case VM_PKT_COMP:
> +					break;
> +
> +				case VM_PKT_DATA_INBAND:
> +					mousevsc_on_receive(
> +						device, desc);
> +					break;
> +
> +				default:
> +					pr_err("unhandled packet type %d, tid %llx len %d\n",
> +						   desc->type,
> +						   req_id,
> +						   bytes_recvd);
> +					break;
> +				}
> +
> +				/* reset */
> +				if (bufferlen > packetSize) {
> +					kfree(buffer);
> +
> +					buffer = packet;
> +					bufferlen = packetSize;
> +				}
> +			} else {
> +				if (bufferlen > packetSize) {
> +					kfree(buffer);
> +
> +					buffer = packet;
> +					bufferlen = packetSize;
> +				}
> +				break;
> +			}
> +		} else if (ret == -ENOBUFS) {
> +			/* Handle large packet */
> +			bufferlen = bytes_recvd;
> +			buffer = kzalloc(bytes_recvd, GFP_ATOMIC);
> +

What happens if we receive even larger amount of data after allocating
the buffer?

> +			if (buffer == NULL) {
> +				buffer = packet;
> +				bufferlen = packetSize;
> +				break;
> +			}
> +		}
> +	} while (1);

So we can be looping indefinitely here as long as other side keeps
sending data?

> +
> +	return;

No naked returns please.

> +}
> +
> +static int mousevsc_connect_to_vsp(struct hv_device *device)
> +{
> +	int ret = 0;
> +	int t;
> +	struct mousevsc_dev *input_dev = hv_get_drvdata(device);
> +	struct mousevsc_prt_msg *request;
> +	struct mousevsc_prt_msg *response;
> +
> +
> +	request = &input_dev->protocol_req;
> +
> +	memset(request, 0, sizeof(struct mousevsc_prt_msg));
> +
> +	request->type = PIPE_MESSAGE_DATA;
> +	request->size = sizeof(struct synthhid_protocol_request);
> +
> +	request->request.header.type = SYNTH_HID_PROTOCOL_REQUEST;
> +	request->request.header.size = sizeof(unsigned int);
> +	request->request.version_requested.version = SYNTHHID_INPUT_VERSION;
> +
> +
> +	ret = vmbus_sendpacket(device->channel, request,
> +				sizeof(struct pipe_prt_msg) -
> +				sizeof(unsigned char) +
> +				sizeof(struct synthhid_protocol_request),
> +				(unsigned long)request,
> +				VM_PKT_DATA_INBAND,
> +				VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> +	if (ret != 0)
> +		goto cleanup;
> +
> +	t = wait_for_completion_timeout(&input_dev->wait_event, 5*HZ);
> +	if (t == 0) {
> +		ret = -ETIMEDOUT;
> +		goto cleanup;
> +	}
> +
> +	response = &input_dev->protocol_resp;
> +
> +	if (!response->response.approved) {
> +		pr_err("synthhid protocol request failed (version %d)",
> +		       SYNTHHID_INPUT_VERSION);
> +		ret = -ENODEV;
> +		goto cleanup;
> +	}
> +
> +	t = wait_for_completion_timeout(&input_dev->wait_event, 5*HZ);

We just completed the wait for this completion, why are we waiting on
the same completion again?

> +	if (t == 0) {
> +		ret = -ETIMEDOUT;
> +		goto cleanup;
> +	}
> +
> +	/*
> +	 * We should have gotten the device attr, hid desc and report
> +	 * desc at this point
> +	 */
> +	if (input_dev->dev_info_status)
> +		ret = -ENOMEM;

-ENOMEM seems wrong.

> +
> +cleanup:
> +
> +	return ret;
> +}
> +
> +static int mousevsc_hid_open(struct hid_device *hid)
> +{
> +	return 0;
> +}
> +
> +static void mousevsc_hid_close(struct hid_device *hid)
> +{
> +}
> +
> +static struct hid_ll_driver mousevsc_ll_driver = {
> +	.open = mousevsc_hid_open,
> +	.close = mousevsc_hid_close,
> +};
> +
> +static struct hid_driver mousevsc_hid_driver;
> +
> +static void reportdesc_callback(struct hv_device *dev, void *packet, u32 len)
> +{

This is called from mousevsc_on_device_add() which is part of device
probe. Why it is split into separate function with bizzare arguments is
beyond me. 

> +	struct hid_device *hid_dev;
> +	struct mousevsc_dev *input_device = hv_get_drvdata(dev);
> +
> +	hid_dev = hid_allocate_device();
> +	if (IS_ERR(hid_dev))
> +		return;

This is not very helpful.

> +
> +	hid_dev->ll_driver = &mousevsc_ll_driver;
> +	hid_dev->driver = &mousevsc_hid_driver;
> +
> +	if (hid_parse_report(hid_dev, packet, len))
> +		return;

Neither is this.

> +
> +	hid_dev->bus = BUS_VIRTUAL;
> +	hid_dev->vendor = input_device->hid_dev_info.vendor;
> +	hid_dev->product = input_device->hid_dev_info.product;
> +	hid_dev->version = input_device->hid_dev_info.version;
> +
> +	sprintf(hid_dev->name, "%s", "Microsoft Vmbus HID-compliant Mouse");
> +
> +	if (!hidinput_connect(hid_dev, 0)) {
> +		hid_dev->claimed |= HID_CLAIMED_INPUT;

Why do you force hidinput claim? Let the normal rules do it.

> +
> +		input_device->connected = 1;

		input_device->connected = true;

> +
> +	}
> +
> +	input_device->hid_device = hid_dev;

This assignment is probably too late.

> +}
> +
> +static int mousevsc_on_device_add(struct hv_device *device)

The only caller of this is mousevsc_probe() so why do you have it>
> +{
> +	int ret = 0;
> +	struct mousevsc_dev *input_dev;
> +
> +	input_dev = alloc_input_device(device);
> +
> +	if (!input_dev)
> +		return -ENOMEM;
> +
> +	input_dev->init_complete = false;
> +
> +	ret = vmbus_open(device->channel,
> +		INPUTVSC_SEND_RING_BUFFER_SIZE,
> +		INPUTVSC_RECV_RING_BUFFER_SIZE,
> +		NULL,
> +		0,
> +		mousevsc_on_channel_callback,
> +		device
> +		);
> +
> +	if (ret != 0) {
> +		free_input_device(input_dev);
> +		return ret;
> +	}
> +
> +
> +	ret = mousevsc_connect_to_vsp(device);
> +
> +	if (ret != 0) {
> +		vmbus_close(device->channel);
> +		free_input_device(input_dev);
> +		return ret;
> +	}
> +
> +
> +	/* workaround SA-167 */
> +	if (input_dev->report_desc[14] == 0x25)
> +		input_dev->report_desc[14] = 0x29;
> +
> +	reportdesc_callback(device, input_dev->report_desc,
> +			    input_dev->report_desc_size);
> +
> +	input_dev->init_complete = true;
> +
> +	return ret;
> +}
> +
> +static int mousevsc_probe(struct hv_device *dev,
> +			const struct hv_vmbus_device_id *dev_id)
> +{
> +
> +	return mousevsc_on_device_add(dev);
> +
> +}
> +
> +static int mousevsc_remove(struct hv_device *dev)
> +{
> +	struct mousevsc_dev *input_dev = hv_get_drvdata(dev);
> +
> +	vmbus_close(dev->channel);
> +
> +	if (input_dev->connected) {
> +		hidinput_disconnect(input_dev->hid_device);
> +		input_dev->connected = 0;
> +		hid_destroy_device(input_dev->hid_device);

hid_destroy_device() should disconnect registered handlers for you; you
do not need to do that manually.

> +	}
> +
> +	free_input_device(input_dev);

Calling it input device is terribly confusing to me. I'd also freed it
inline (and used gotos to unwind errors in probe()).

> +
> +	return 0;
> +}
> +
> +static const struct hv_vmbus_device_id id_table[] = {
> +	/* Mouse guid */
> +	{ VMBUS_DEVICE(0x9E, 0xB6, 0xA8, 0xCF, 0x4A, 0x5B, 0xc0, 0x4c,
> +		       0xB9, 0x8B, 0x8B, 0xA1, 0xA1, 0xF3, 0xF9, 0x5A) },
> +	{ },
> +};
> +
> +MODULE_DEVICE_TABLE(vmbus, id_table);
> +
> +static struct  hv_driver mousevsc_drv = {
> +	.name = "mousevsc",
> +	.id_table = id_table,
> +	.probe = mousevsc_probe,
> +	.remove = mousevsc_remove,
> +};
> +
> +static int __init mousevsc_init(void)
> +{
> +	return vmbus_driver_register(&mousevsc_drv);
> +}
> +
> +static void __exit mousevsc_exit(void)
> +{
> +	vmbus_driver_unregister(&mousevsc_drv);
> +}
> +
> +MODULE_LICENSE("GPL");
> +MODULE_VERSION(HV_DRV_VERSION);
> +module_init(mousevsc_init);
> +module_exit(mousevsc_exit);

Thanks.

-- 
Dmitry

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