Re: [RFC] app/testpmd: use RSS conf from software when configuring DCB

[zhoumin <zhoumin@loongson.cn>]

Hi Stephen,

Sorry for the delay.

On Thur, Oct 10 at 2024 6:30AM, Stephen Hemminger wrote:
> On Wed, 12 Apr 2023 17:52:39 +0800
> Min Zhou <zhoumin@loongson.cn> wrote:
>
>> In the testpmd command, we have to stop the port firstly before configuring
>> the DCB. However, some PMDs may execute a hardware reset during the port
>> stop, such as ixgbe. Some kind of reset operations of PMD could clear the
>> configurations of RSS in the hardware register. This would cause the loss
>> of RSS configurations that were set during the testpmd initialization. As
>> a result, I find that I cannot enable RSS and DCB at the same time in the
>> testpmd command when using Intel 82599 NIC.
>>
>> Although this patch can solve the problem I encountered, is there any risk
>> of using rss conf from software instead of reading from the hardware
>> register when configuring DCB?
>>
>> Signed-off-by: Min Zhou <zhoumin@loongson.cn>
>> ---
>>   app/test-pmd/testpmd.c | 11 +----------
>>   1 file changed, 1 insertion(+), 10 deletions(-)
>>
>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
>> index 5cb6f92523..3c382267b8 100644
>> --- a/app/test-pmd/testpmd.c
>> +++ b/app/test-pmd/testpmd.c
>> @@ -4247,14 +4247,12 @@ const uint16_t vlan_tags[] = {
>>   };
>>   
>>   static  int
>> -get_eth_dcb_conf(portid_t pid, struct rte_eth_conf *eth_conf,
>> +get_eth_dcb_conf(portid_t pid __rte_unused, struct rte_eth_conf *eth_conf,
>>   		 enum dcb_mode_enable dcb_mode,
>>   		 enum rte_eth_nb_tcs num_tcs,
>>   		 uint8_t pfc_en)
>>   {
>>   	uint8_t i;
>> -	int32_t rc;
>> -	struct rte_eth_rss_conf rss_conf;
>>   
> Sorry for the late review, but almost uses DCB and fewer still with DPDK;
> so not surprised that there would be issues like this.
>
> If you change an internal function like get_eth_dcb_conf to remove parameters
> then do not mark those parameters as unused, instead remove them from the function
> and the caller. Plus the function now always returns 0 so it can be reset as void.
> first place.

Yes, I agree with your point. Thanks for providing the suggested codes. 
I have tested this change and it can solve the problem. I will send the 
V2 version.

Best Regards,

Min Zhou

>
> Suggest the following (untested):
>
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
> index b1401136e4..5eaac752c6 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -4291,15 +4291,11 @@ const uint16_t vlan_tags[] = {
>   		24, 25, 26, 27, 28, 29, 30, 31
>   };
>   
> -static  int
> -get_eth_dcb_conf(portid_t pid, struct rte_eth_conf *eth_conf,
> -		 enum dcb_mode_enable dcb_mode,
> -		 enum rte_eth_nb_tcs num_tcs,
> -		 uint8_t pfc_en)
> +static void
> +get_eth_dcb_conf(struct rte_eth_conf *eth_conf, enum dcb_mode_enable dcb_mode,
> +		 enum rte_eth_nb_tcs num_tcs, uint8_t pfc_en)
>   {
>   	uint8_t i;
> -	int32_t rc;
> -	struct rte_eth_rss_conf rss_conf;
>   
>   	/*
>   	 * Builds up the correct configuration for dcb+vt based on the vlan tags array
> @@ -4341,12 +4337,6 @@ get_eth_dcb_conf(portid_t pid, struct rte_eth_conf *eth_conf,
>   		struct rte_eth_dcb_tx_conf *tx_conf =
>   				&eth_conf->tx_adv_conf.dcb_tx_conf;
>   
> -		memset(&rss_conf, 0, sizeof(struct rte_eth_rss_conf));
> -
> -		rc = rte_eth_dev_rss_hash_conf_get(pid, &rss_conf);
> -		if (rc != 0)
> -			return rc;
> -
>   		rx_conf->nb_tcs = num_tcs;
>   		tx_conf->nb_tcs = num_tcs;
>   
> @@ -4358,7 +4348,6 @@ get_eth_dcb_conf(portid_t pid, struct rte_eth_conf *eth_conf,
>   		eth_conf->rxmode.mq_mode =
>   				(enum rte_eth_rx_mq_mode)
>   					(rx_mq_mode & RTE_ETH_MQ_RX_DCB_RSS);
> -		eth_conf->rx_adv_conf.rss_conf = rss_conf;
>   		eth_conf->txmode.mq_mode = RTE_ETH_MQ_TX_DCB;
>   	}
>   
> @@ -4367,8 +4356,6 @@ get_eth_dcb_conf(portid_t pid, struct rte_eth_conf *eth_conf,
>   				RTE_ETH_DCB_PG_SUPPORT | RTE_ETH_DCB_PFC_SUPPORT;
>   	else
>   		eth_conf->dcb_capability_en = RTE_ETH_DCB_PG_SUPPORT;
> -
> -	return 0;
>   }
>   
>   int
> @@ -4391,10 +4378,9 @@ init_port_dcb_config(portid_t pid,
>   	/* retain the original device configuration. */
>   	memcpy(&port_conf, &rte_port->dev_conf, sizeof(struct rte_eth_conf));
>   
> -	/*set configuration of DCB in vt mode and DCB in non-vt mode*/
> -	retval = get_eth_dcb_conf(pid, &port_conf, dcb_mode, num_tcs, pfc_en);
> -	if (retval < 0)
> -		return retval;
> +	/* set configuration of DCB in vt mode and DCB in non-vt mode */
> +	get_eth_dcb_conf(&port_conf, dcb_mode, num_tcs, pfc_en);
> +
>   	port_conf.rxmode.offloads |= RTE_ETH_RX_OFFLOAD_VLAN_FILTER;
>   	/* remove RSS HASH offload for DCB in vt mode */
>   	if (port_conf.rxmode.mq_mode == RTE_ETH_MQ_RX_VMDQ_DCB) {