Re: [dpdk-dev] [RFC] ethdev: improve link speed to string

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 9/16/21 5:56 AM, Min Hu (Connor) wrote:
> Currently, link speed to string only supports specific speeds, like 10M,
> 100M, 1G etc.
> 
> This patch expands support for any link speed which is over 1M and one
> decimal place will kept for display at most.
> 
> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> ---
>  lib/ethdev/rte_ethdev.c | 34 +++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index daf5ca9242..1d3b960305 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -2750,24 +2750,24 @@ rte_eth_link_get_nowait(uint16_t port_id, struct rte_eth_link *eth_link)
>  const char *
>  rte_eth_link_speed_to_str(uint32_t link_speed)
>  {
> -	switch (link_speed) {
> -	case ETH_SPEED_NUM_NONE: return "None";
> -	case ETH_SPEED_NUM_10M:  return "10 Mbps";
> -	case ETH_SPEED_NUM_100M: return "100 Mbps";
> -	case ETH_SPEED_NUM_1G:   return "1 Gbps";
> -	case ETH_SPEED_NUM_2_5G: return "2.5 Gbps";
> -	case ETH_SPEED_NUM_5G:   return "5 Gbps";
> -	case ETH_SPEED_NUM_10G:  return "10 Gbps";
> -	case ETH_SPEED_NUM_20G:  return "20 Gbps";
> -	case ETH_SPEED_NUM_25G:  return "25 Gbps";
> -	case ETH_SPEED_NUM_40G:  return "40 Gbps";
> -	case ETH_SPEED_NUM_50G:  return "50 Gbps";
> -	case ETH_SPEED_NUM_56G:  return "56 Gbps";
> -	case ETH_SPEED_NUM_100G: return "100 Gbps";
> -	case ETH_SPEED_NUM_200G: return "200 Gbps";
> -	case ETH_SPEED_NUM_UNKNOWN: return "Unknown";
> -	default: return "Invalid";
> +#define SPEED_STRING_LEN 16
> +	static char name[SPEED_STRING_LEN];

NACK

Nothing good will happen if you try to use the function to
print two different link speeds in one log message.

> +
> +	if (link_speed == ETH_SPEED_NUM_NONE)
> +		return "None";
> +	if (link_speed == ETH_SPEED_NUM_UNKNOWN)
> +		return "Unknown";
> +	if (link_speed < ETH_SPEED_NUM_1G) {
> +		snprintf(name, sizeof(name), "%u Mbps", link_speed);
> +	} else if (link_speed % ETH_SPEED_NUM_1G != 0) {
> +		snprintf(name, sizeof(name), "%.1f Gbps",
> +		(double)link_speed / ETH_SPEED_NUM_1G);
> +	} else {
> +		snprintf(name, sizeof(name), "%u Gbps",
> +		link_speed / ETH_SPEED_NUM_1G);
>  	}
> +
> +	return (const char *)name;
>  }
>  
>  int
>