Re: [PATCH v9 1/3] net/macb: add new poll mode driver

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri,  6 Jun 2025 09:06:10 +0000
Wencheng Li <liwencheng@phytium.com.cn> wrote:

> +static int macb_get_speed_info(struct rte_eth_dev *dev, char *speed_info)
> +{
> +	char filename[PATH_MAX];
> +	char *s;
> +	struct macb_priv *priv = dev->data->dev_private;
> +
> +	if (!speed_info) {
> +		MACB_LOG(ERR, "speed info is NULL.");
> +		return -ENOMEM;
> +	}
> +
> +	snprintf(filename, PATH_MAX, "%s/%s/speed_info", MACB_PDEV_PATH, priv->name);
> +	FILE *file = fopen(filename, "r");
> +	if (!file) {
> +		MACB_LOG(ERR, "There is no speed_info file!");
> +		return -ENFILE;
> +	}
> +
> +	s = fgets(speed_info, SPEED_INFO_LEN, file);
> +	if (!s) {
> +		fclose(file);
> +		MACB_LOG(ERR, "get speed info error!");
> +		return -EINVAL;
> +	}
> +
> +	fclose(file);
> +	return 0;
> +}

Looking at this API I see a potential review conflict.
Although sysfs is a text based API, and any string can be returned;
the convention used is one value per file.

Writing UIO drivers is hard, and getting it upstream you will find lots of issues;
ask Long about hyper-v uio. I wonder if there is a better way to do this.