Re: [dpdk-dev] [PATCH 2/3] app/testpmd: fix RSS hash type update

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

On 9/10/21 12:57 PM, Maxime Coquelin wrote:
> 
> 
> On 9/10/21 11:51 AM, Andrew Rybchenko wrote:
>> On 9/10/21 12:17 PM, Maxime Coquelin wrote:
>>> port_rss_hash_key_update() initializes rss_conf with the
>>> RSS hash type and key provided by the user, but it calls
>>> rte_eth_dev_rss_hash_conf_get() before calling
>>> rte_eth_dev_rss_hash_update(), which overides the parsed
>>> config with current NIC's config.
>>>
>>> While the RSS key value is set again after, this is not
>>> the case of the key length and the type of hash.
>>>
>>> There is no need to read the RSS config from the NIC, let's
>>> just try to set the user defined one.
>>>
>>> Fixes: 8205e241b2b0 ("app/testpmd: add missing type to RSS hash commands")
>>> Cc: stable@dpdk.org
>>> Cc: nelio.laranjeiro@6wind.com
>>>
>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>> ---
>>>  app/test-pmd/config.c | 8 ++------
>>>  1 file changed, 2 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
>>> index 31d8ba1b91..451bda53b1 100644
>>> --- a/app/test-pmd/config.c
>>> +++ b/app/test-pmd/config.c
>>> @@ -2853,18 +2853,14 @@ port_rss_hash_key_update(portid_t port_id, char rss_type[], uint8_t *hash_key,
>>>  	int diag;
>>>  	unsigned int i;
>>>  
>>> -	rss_conf.rss_key = NULL;
>>> +	rss_conf.rss_key = hash_key;
>>>  	rss_conf.rss_key_len = hash_key_len;
>>>  	rss_conf.rss_hf = 0;
>>>  	for (i = 0; rss_type_table[i].str; i++) {
>>>  		if (!strcmp(rss_type_table[i].str, rss_type))
>>>  			rss_conf.rss_hf = rss_type_table[i].rss_type;
>>>  	}
>>> -	diag = rte_eth_dev_rss_hash_conf_get(port_id, &rss_conf);
>>> -	if (diag == 0) {
>>> -		rss_conf.rss_key = hash_key;
>>> -		diag = rte_eth_dev_rss_hash_update(port_id, &rss_conf);
>>> -	}
>>> +	diag = rte_eth_dev_rss_hash_update(port_id, &rss_conf);
>>
>> I'm not 100% sure, but I'd say the intent above could be
>> to update key only as the function name says. I.e. keep
>> rss_hf as is. That could be the reason to get first.
>>
> 
> I think that was the intial purpose of the command, but patch
> 8205e241b2b0 added setting the hash type as mandatory. There are
> no other command to configure the hash type from testpmd AFAICT.
> 
> Also, even without 8205e241b2b0, the function was broken because the
> key length was overiden.

I see, many thanks for explanations.