Re: [PATCH v5 1/6] misc: Add Synopsys DesignWare xData IP driver

[Greg Kroah-Hartman]

On Thu, Feb 11, 2021 at 10:08:38AM +0100, Gustavo Pimentel wrote:
> +static ssize_t write_show(struct device *dev, struct device_attribute *attr,
> +			  char *buf)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	struct dw_xdata *dw = pci_get_drvdata(pdev);
> +	u64 rate;
> +
> +	mutex_lock(&dw->mutex);
> +	dw_xdata_perf(dw, &rate, true);
> +	mutex_unlock(&dw->mutex);
> +
> +	return sysfs_emit(buf, "%llu MB/s\n", rate);

Do not put units in a sysfs file, that should be in the documentation,
otherwise this forces userspace to "parse" the units which is a mess.

Same for the other sysfs file.

And why do you need a lock for this show function?

thanks,

greg k-h