From ae08d50d862073a8c53ed7ab4159f3125595667b Mon Sep 17 00:00:00 2001
From: Chengwen Feng <fengchengwen@huawei.com>
Date: Fri, 13 May 2022 10:53:51 +0800
Subject: [PATCH 089/122] net/hns3: fix xstats get return if xstats is null
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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>
---
 drivers/net/hns3/hns3_stats.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hns3/hns3_stats.c b/drivers/net/hns3/hns3_stats.c
index 9b7ad067aa..e69761c8b3 100644
--- 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;
-- 
2.22.0

