RE: [PATCH] HID: hyperv: make sure input buffer is big enough

[KY Srinivasan]

> -----Original Message-----
> From: David Herrmann [mailto:dh.herrmann@xxxxxxxxx]
> Sent: Thursday, December 19, 2013 3:32 AM
> To: linux-input@xxxxxxxxxxxxxxx
> Cc: Jiri Kosina; Dan Carpenter; Joseph Salisbury; KY Srinivasan; Haiyang Zhang;
> linux-kernel@xxxxxxxxxxxxxxx; David Herrmann
> Subject: [PATCH] HID: hyperv: make sure input buffer is big enough
> 
> We need at least HID_MAX_BUFFER_SIZE (4096) bytes as input buffer. HID
> core depends on this as it requires every input report to be at least as
> big as advertised.
> 
> Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>

Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>

> ---
> Hi
> 
> Same as for the HIDP patch, if there's a way to avoid the extra copy, please
> provide a better patch.
> 
> Thanks
> David
> 
>  drivers/hid/hid-hyperv.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
> index 8fae6d1..c24908f 100644
> --- a/drivers/hid/hid-hyperv.c
> +++ b/drivers/hid/hid-hyperv.c
> @@ -157,6 +157,7 @@ struct mousevsc_dev {
>  	u32			report_desc_size;
>  	struct hv_input_dev_info hid_dev_info;
>  	struct hid_device       *hid_device;
> +	u8			input_buf[HID_MAX_BUFFER_SIZE];
>  };
> 
> 
> @@ -256,6 +257,7 @@ static void mousevsc_on_receive(struct hv_device
> *device,
>  	struct synthhid_msg *hid_msg;
>  	struct mousevsc_dev *input_dev = hv_get_drvdata(device);
>  	struct synthhid_input_report *input_report;
> +	size_t len;
> 
>  	pipe_msg = (struct pipe_prt_msg *)((unsigned long)packet +
>  						(packet->offset8 << 3));
> @@ -300,9 +302,12 @@ static void mousevsc_on_receive(struct hv_device
> *device,
>  			(struct synthhid_input_report *)pipe_msg->data;
>  		if (!input_dev->init_complete)
>  			break;
> -		hid_input_report(input_dev->hid_device,
> -				HID_INPUT_REPORT, input_report->buffer,
> -				input_report->header.size, 1);
> +
> +		len = min(input_report->header.size,
> +			  (u32)sizeof(input_dev->input_buf));
> +		memcpy(input_dev->input_buf, input_report->buffer, len);
> +		hid_input_report(input_dev->hid_device, HID_INPUT_REPORT,
> +				 input_dev->input_buf, len, 1);
>  		break;
>  	default:
>  		pr_err("unsupported hid msg type - type %d len %d",
> --
> 1.8.5.1

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