net/hns3: fix xstats get return if xstats is null

Many user (e.g. telemetry) invokes rte_eth_xstats_get(port_id, NULL, 0)
to retrieve the required number of elements, but currently hns3 PMD
returns zero when xstats is null.

Dedicated check for xstats vs null is not required, since ethdev layer
guarantees that it may be null only if number of entries n is 0 (which
is definitely smaller than total xstats count).

Fixes: 8839c5e202f3 ("net/hns3: support device stats")
Cc: stable@dpdk.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>

diff --git a/drivers/net/hns3/hns3_stats.c b/drivers/net/hns3/hns3_stats.c
index 2799ff4432699f0a4bf2eef45ea9e8986ca1ee10..07fad0348584649563b0b4ce185bb9555782ebdc 100644 (file)
--- a/drivers/net/hns3/hns3_stats.c
+++ b/drivers/net/hns3/hns3_stats.c
@@ -1031,9 +1031,13 @@ hns3_imissed_stats_get(struct rte_eth_dev *dev, struct rte_eth_xstat *xstats,
  * @praram xstats
  *   A pointer to a table of structure of type *rte_eth_xstat*
  *   to be filled with device statistics ids and values.
- *   This parameter can be set to NULL if n is 0.
+ *   This parameter can be set to NULL if and only if n is 0.
  * @param n
  *   The size of the xstats array (number of elements).
+ *   If lower than the required number of elements, the function returns the
+ *   required number of elements.
+ *   If equal to zero, the xstats parameter must be NULL, the function returns
+ *   the required number of elements.
  * @return
  *   0 on fail, count(The size of the statistics elements) on success.
  */
@@ -1052,9 +1056,6 @@ hns3_dev_xstats_get(struct rte_eth_dev *dev, struct rte_eth_xstat *xstats,
        int count;
        int ret;
 
-       if (xstats == NULL)
-               return 0;
-
        count = hns3_xstats_calc_num(dev);
        if ((int)n < count)
                return count;