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

[Andrew Rybchenko <arybchenko@solarflare.com>]

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.

>   * @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.