Re: [dpdk-dev] [PATCH] ethdev: decrease log level for successful API

[Kevin Traynor <ktraynor@redhat.com>]

On 08/02/2018 03:41 PM, Andrew Rybchenko wrote:
> On 02.08.2018 17:09, Kevin Traynor wrote:
>> On 08/02/2018 02:52 PM, Andrew Rybchenko wrote:
>>> On 02.08.2018 16:35, Kevin Traynor wrote:
>>>> On 08/02/2018 01:59 PM, Andrew Rybchenko wrote:
>>>>> On 02.08.2018 15:33, Kevin Traynor wrote:
>>>>>> Change log level of messages from ERR back to DEBUG where
>>>>>> existing API indicates that the condition is a success.
>>>>>>
>>>>>> This means applications using the API in its current form will
>>>>>> not get new ERR logs.
>>>>>>
>>>>>> Fixes: bea1e0c70cfc ("ethdev: convert static log type usage to
>>>>>> dynamic")
>>>>>>
>>>>>> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
>>>>>> ---
>>>>>>     lib/librte_ethdev/rte_ethdev.c | 12 ++++++------
>>>>>>     1 file changed, 6 insertions(+), 6 deletions(-)
>>>>>>
>>>>>> diff --git a/lib/librte_ethdev/rte_ethdev.c
>>>>>> b/lib/librte_ethdev/rte_ethdev.c
>>>>>> index c7ab157..16656d2 100644
>>>>>> --- a/lib/librte_ethdev/rte_ethdev.c
>>>>>> +++ b/lib/librte_ethdev/rte_ethdev.c
>>>>>> @@ -797,5 +797,5 @@ struct rte_eth_dev *
>>>>>>           if (dev->data->rx_queue_state[rx_queue_id] !=
>>>>>> RTE_ETH_QUEUE_STATE_STOPPED) {
>>>>>> -        RTE_ETHDEV_LOG(ERR,
>>>>>> +        RTE_ETHDEV_LOG(DEBUG,
>>>>>>                 "Queue %"PRIu16" of device with port_id=%"PRIu16"
>>>>>> already started\n",
>>>>>>                 rx_queue_id, port_id);
>>>>>> @@ -824,5 +824,5 @@ struct rte_eth_dev *
>>>>>>           if (dev->data->rx_queue_state[rx_queue_id] ==
>>>>>> RTE_ETH_QUEUE_STATE_STOPPED) {
>>>>>> -        RTE_ETHDEV_LOG(ERR,
>>>>>> +        RTE_ETHDEV_LOG(DEBUG,
>>>>>>                 "Queue %"PRIu16" of device with port_id=%"PRIu16"
>>>>>> already stopped\n",
>>>>>>                 rx_queue_id, port_id);
>>>>>> @@ -857,5 +857,5 @@ struct rte_eth_dev *
>>>>>>           if (dev->data->tx_queue_state[tx_queue_id] !=
>>>>>> RTE_ETH_QUEUE_STATE_STOPPED) {
>>>>>> -        RTE_ETHDEV_LOG(ERR,
>>>>>> +        RTE_ETHDEV_LOG(DEBUG,
>>>>>>                 "Queue %"PRIu16" of device with port_id=%"PRIu16"
>>>>>> already started\n",
>>>>>>                 tx_queue_id, port_id);
>>>>>> @@ -882,5 +882,5 @@ struct rte_eth_dev *
>>>>>>           if (dev->data->tx_queue_state[tx_queue_id] ==
>>>>>> RTE_ETH_QUEUE_STATE_STOPPED) {
>>>>>> -        RTE_ETHDEV_LOG(ERR,
>>>>>> +        RTE_ETHDEV_LOG(DEBUG,
>>>>>>                 "Queue %"PRIu16" of device with port_id=%"PRIu16"
>>>>>> already stopped\n",
>>>>>>                 tx_queue_id, port_id);
>>>>>> @@ -1287,5 +1287,5 @@ struct rte_eth_dev *
>>>>>>           if (dev->data->dev_started != 0) {
>>>>>> -        RTE_ETHDEV_LOG(ERR,
>>>>>> +        RTE_ETHDEV_LOG(DEBUG,
>>>>>>                 "Device with port_id=%"PRIu16" already started\n",
>>>>>>                 port_id);
>>>>>> @@ -1319,5 +1319,5 @@ struct rte_eth_dev *
>>>>>>           if (dev->data->dev_started == 0) {
>>>>>> -        RTE_ETHDEV_LOG(ERR,
>>>>>> +        RTE_ETHDEV_LOG(DEBUG,
>>>>>>                 "Device with port_id=%"PRIu16" already stopped\n",
>>>>>>                 port_id);
>>>>> I would suggest to use WARNING here. Yes, it is not an error since
>>>>> nothing bad has
>>>>> happened and we handle duplicate stop and duplicate start,
>>>>> but I think it is bad that (buggy?) application does it. Making it
>>>>> debug
>>>>> we simply
>>>>> hide it too much.
>>>>>
>>>> I think an application following the documented API is not bad or
>>>> buggy.
>>> I've failed to find the place were it is documented that device/queue
>>> may be stopped/started twice. Could you point out?
>>> Yes, return value 0 means success, but it is a separate thing.
>>>
>> I was commenting directly on the API and it's documentation e.g. below
>> for dev start. I'm not aware of other documentation specifying how it
>> can/cannot be called.
> 
> I would not say so. "0: Success. Ethernet device started" means that
> function managed to do the job and finally the device is started.
> 
> Never-mind it is not that important and already paid to much attention.
> I've included in CC other ethdev maintainers (who should be there from
> the very beginning). I don't mind if it is acked by other ethdev maintainer
> and applied. It is definitely not an error as it is now. Thanks.
> 

Sure, sounds good - I'm glad we agree on something :-) I'll leave it for
a day and can re-spin tomorrow.

thanks,
Kevin.

>>   * @return
>>   *   - 0: Success, Ethernet device started.
>>   *   - <0: Error code of the driver device start function.
>>   */
>> int rte_eth_dev_start(uint16_t port_id);
>>
>> int
>> rte_eth_dev_start(uint16_t port_id)
>> {
>> ...
>>     if (dev->data->dev_started != 0) {
>>         RTE_ETHDEV_LOG(DEBUG,
>>             "Device with port_id=%"PRIu16" already started\n",
>>             port_id);
>>         return 0;
>>     }
>> ...
>> }
>>
>>
>>>> An application may not maintain some state and always call a stop
>>>> before
>>>> a start etc. in line with the API.
>>>>
>>>> I don't think an API success condition should be changed from a debug
>>>> message to anything else. Otherwise, it is trying to flag a warning
>>>> about the application which is following the API! It and will just
>>>> spook
>>>> people when they see a new warning.
>