Re: [PATCH v1 2/4] xhci: dbc: allow to set serial number through sysfs

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Sep 29, 2025 at 09:02:04AM +0000, Łukasz Bartosik wrote:
> From: Łukasz Bartosik <ukaszb@chromium.org>
> 
> Add code which allows to set serial number of a DbC
> device through sysfs.
> 
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> ---
>  drivers/usb/host/xhci-dbgcap.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci-dbgcap.c b/drivers/usb/host/xhci-dbgcap.c
> index c2fecaffd6f3..5cc201afe8f4 100644
> --- a/drivers/usb/host/xhci-dbgcap.c
> +++ b/drivers/usb/host/xhci-dbgcap.c
> @@ -1200,6 +1200,36 @@ static ssize_t dbc_bcdDevice_store(struct device *dev,
>  	return size;
>  }
>  
> +static ssize_t dbc_iSerial_show(struct device *dev,
> +			    struct device_attribute *attr,
> +			    char *buf)
> +{
> +	struct xhci_hcd	*xhci = hcd_to_xhci(dev_get_drvdata(dev));
> +	struct xhci_dbc	*dbc = xhci->dbc;
> +
> +	return sysfs_emit(buf, "%s\n", dbc->str.serial);
> +}
> +
> +static ssize_t dbc_iSerial_store(struct device *dev,
> +			     struct device_attribute *attr,
> +			     const char *buf, size_t size)
> +{
> +	struct xhci_hcd	*xhci = hcd_to_xhci(dev_get_drvdata(dev));
> +	struct xhci_dbc	*dbc = xhci->dbc;
> +
> +	if (dbc->state != DS_DISABLED)
> +		return -EBUSY;
> +
> +	if (size > USB_MAX_STRING_LEN/2+1)
> +		return -E2BIG;
> +
> +	memcpy(dbc->str.serial, buf, size);
> +	/* remove newline and terminate the string */
> +	dbc->str.serial[size-1] = '\0';

What if there is not a newline?