On 9/28/21 7:50 PM, Ferruh Yigit wrote:

On 9/28/2021 1:05 PM, Andrew Rybchenko wrote:

quoted

From: Ivan Ilchenko <redacted>

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 <redacted>
Signed-off-by: Andrew Rybchenko <redacted>
Reviewed-by: Andy Moreton <redacted>
---
 lib/ethdev/ethdev_driver.h | 42 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/lib/ethdev/ethdev_driver.h b/lib/ethdev/ethdev_driver.h
index 40e474aa7e..c89eefcc42 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 +235,31 @@ 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.

Why limiting this behavior to 'xstats_get_names_by_id'?

Internally 'xstats_get_names_by_id' is used to get the count, but I think this
is not intentionally selected, just one of the xstats_*_by_id dev_ops used.

I think it is confusing to have this support for one of the '_by_id' dev_ops but
not for other. Why not require both to support returning 'count'?

Simply because it is dead code. There is no point to require
from driver to have dead code.