Re: [dpdk-dev] [PATCH v2 1/5] kni: add API to set link status on kernel interface

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 9/19/2018 8:55 PM, Dan Gora wrote:
> Add a new API function to KNI, rte_kni_update_link() to allow DPDK
> applications to update the link status for KNI network interfaces in
> the linux kernel.
> 
> Signed-off-by: Dan Gora <dg@adax.com>

<...>

> +int __rte_experimental
> +rte_kni_update_link(struct rte_kni *kni, struct rte_eth_link *link)
> +{
> +	char path[64];
> +	char carrier[2];
> +	const char *new_carrier;
> +	int fd, ret;
> +
> +	if (kni == NULL || link == NULL)
> +		return -1;
> +
> +	snprintf(path, sizeof(path), "/sys/devices/virtual/net/%s/carrier",
> +		kni->name);
> +
> +	fd = open(path, O_RDWR);
> +	if (fd == -1) {
> +		RTE_LOG(ERR, KNI, "Failed to open file: %s.\n", path);
> +		return -1;
> +	}
> +
> +	ret = read(fd, carrier, 2);
> +	if (ret < 1) {
> +		/* Cannot read carrier until interface is marked
> +		 * 'up', so don't log an error.
> +		 */
> +		close(fd);
> +		return -1;
> +	}
> +
> +	new_carrier = (link->link_status == ETH_LINK_UP) ? "1" : "0";
> +	ret = write(fd, new_carrier, 1);
> +	if (ret < 1) {
> +		RTE_LOG(ERR, KNI, "Failed to write file: %s.\n", path);
> +		close(fd);
> +		return -1;
> +	}
> +
> +	if (strncmp(carrier, new_carrier, 1)) {
> +		if (link->link_status == ETH_LINK_UP) {
> +			RTE_LOG(INFO, KNI, "%s NIC Link is Up %d Mbps %s %s.\n",
> +				kni->name,
> +				link->link_speed,
> +				link->link_autoneg ? "(AutoNeg)" : "(Fixed)",
> +				link->link_duplex ?
> +					"Full Duplex" : "Half Duplex");

These link values are coming from user and not reflected to the kni interface,
printing them here can cause a misunderstanding that they have been applied.
I think only link status should be printed here.

<...>

> @@ -148,9 +239,16 @@ test_kni_loop(__rte_unused void *arg)
>  			ret = -1;
>  		if (system(IFCONFIG TEST_KNI_PORT" mtu 1400") == -1)
>  			ret = -1;
> +
> +		ret = kni_change_link();
> +		if (ret != 0) {
> +			test_kni_processing_flag = 1;
> +			return ret;
> +		}

I thinks this is wrong place to call kni_change_link(), this is test_kni_loop()
created by test_kni_processing() that does packet processing tests.

I think better to call directly from test_kni(), perhaps before
test_kni_processing() call?