Re: [dpdk-dev] [PATCH v4 2/2] ethdev: fix docs of drivers callbacks getting xstats by IDs

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

On 7/26/21 1:13 PM, Olivier Matz wrote:
> On Sat, Jul 24, 2021 at 03:33:14PM +0300, Andrew Rybchenko wrote:
>> From: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
>>
>> Update xstats by IDs callbacks documentation in accordance with
>> ethdev usage of these callbacks. Document valid combinations of
>> input arguments to make driver implementation simpler.
>>
>> Fixes: 79c913a42f0 ("ethdev: retrieve xstats by ID")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
>> Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
>> Reviewed-by: Andy Moreton <amoreton@xilinx.com>
>> ---
>>  lib/ethdev/ethdev_driver.h | 43 ++++++++++++++++++++++++++++++++++++--
>>  1 file changed, 41 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
>> index 40e474aa7e..fd5b7ca550 100644
>> --- a/lib/ethdev/ethdev_driver.h
>> +++ b/lib/ethdev/ethdev_driver.h
>> @@ -187,11 +187,28 @@ typedef int (*eth_xstats_get_t)(struct rte_eth_dev *dev,
>>  	struct rte_eth_xstat *stats, unsigned int n);
>>  /**< @internal Get extended stats of an Ethernet device. */
>>  
>> +/**
>> + * @internal
>> + * Get extended stats of an Ethernet device.
>> + *
>> + * @param dev
>> + *   ethdev handle of port.
>> + * @param ids
>> + *   IDs array to retrieve specific statistics. Must not be NULL.
>> + * @param values
>> + *   A pointer to a table to be filled with device statistics values.
>> + *   Must not be NULL.
>> + * @param n
>> + *   Element count in @p ids and @p values
>> + *
>> + * @return
>> + *   - A number of filled in stats.
>> + *   - A negative value on error.
>> + */
>>  typedef int (*eth_xstats_get_by_id_t)(struct rte_eth_dev *dev,
>>  				      const uint64_t *ids,
>>  				      uint64_t *values,
>>  				      unsigned int n);
>> -/**< @internal Get extended stats of an Ethernet device. */
>>  
>>  /**
>>   * @internal
>> @@ -218,10 +235,32 @@ typedef int (*eth_xstats_get_names_t)(struct rte_eth_dev *dev,
>>  	struct rte_eth_xstat_name *xstats_names, unsigned int size);
>>  /**< @internal Get names of extended stats of an Ethernet device. */
>>  
>> +/**
>> + * @internal
>> + * Get names of extended stats of an Ethernet device.
>> + * For name count, set @p xstats_names and @p ids to NULL.
>> + *
>> + * @param dev
>> + *   ethdev handle of port.
>> + * @param xstats_names
>> + *   An rte_eth_xstat_name array of at least *size* elements to
>> + *   be filled. Can be NULL together with @p ids to retrieve number of
>> + *   available statistics.
>> + * @param ids
>> + *   IDs array to retrieve specific statistics. Can be NULL together
>> + *   with @p xstats_names to retrieve number of available statistics.
>> + * @param size
>> + *   Size of ids and xstats_names arrays.
>> + *   Element count in @p ids and @p xstats_names
> 
> I think only the second line should be kept.

Thanks, fixed in v5.

> 
> Shouldn't we also say here that size should be 0 if arrays are NULL?

In this particular case I don't think so. ethdev layer
guarantees that the parameter is 0 if both array pointers
are NULL. PMD should not care about it.

> 
>> + *
>> + * @return
>> + *   - A number of filled in stats if both xstats_names and ids are not NULL.
>> + *   - A number of available stats if both xstats_names and ids are NULL.
>> + *   - A negative value on error.
>> + */
>>  typedef int (*eth_xstats_get_names_by_id_t)(struct rte_eth_dev *dev,
>>  	struct rte_eth_xstat_name *xstats_names, const uint64_t *ids,
>>  	unsigned int size);
>> -/**< @internal Get names of extended stats of an Ethernet device. */
>>  
>>  typedef int (*eth_queue_stats_mapping_set_t)(struct rte_eth_dev *dev,
>>  					     uint16_t queue_id,
>> -- 
>> 2.30.2
>>