[dpdk-stable] [PATCH] [18.11] net/mlx5: fix xstats reset reinitialization

[Shiri Kuzin]

[ upstream commit 42dcd453d9b63841a5460a6ca3872eb7648d73bd ]

The mlx5_xstats_reset clears the device extended statistics.
In this function the driver may reinitialize the structures
that are used to read device counters.

In case of reinitialization, the number of counters may
change, which wouldn't be taken into account by the
reset API callback and can cause a segmentation fault.

This issue is fixed by allocating the counters size after
the reinitialization.

Fixes: a4193ae3bc4f ("net/mlx5: support extended statistics")

Reported-by: Ralf Hoffmann <ralf.hoffmann at allegro-packets.com>
Signed-off-by: Shiri Kuzin <shirik at nvidia.com>
Acked-by: Matan Azrad <matan at nvidia.com>
---
 drivers/net/mlx5/mlx5_stats.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_stats.c b/drivers/net/mlx5/mlx5_stats.c
index 6906dc81cc..38a2ffba4a 100644
--- a/drivers/net/mlx5/mlx5_stats.c
+++ b/drivers/net/mlx5/mlx5_stats.c
@@ -473,8 +473,7 @@ mlx5_xstats_reset(struct rte_eth_dev *dev)
 	struct mlx5_xstats_ctrl *xstats_ctrl = &priv->xstats_ctrl;
 	int stats_n;
 	unsigned int i;
-	unsigned int n = xstats_ctrl->mlx5_stats_n;
-	uint64_t counters[n];
+	uint64_t *counters;
 	int ret;
 
 	stats_n = mlx5_ethtool_get_stats_n(dev);
@@ -485,14 +484,27 @@ mlx5_xstats_reset(struct rte_eth_dev *dev)
 	}
 	if (xstats_ctrl->stats_n != stats_n)
 		mlx5_stats_init(dev);
+	counters =  malloc(sizeof(*counters) * xstats_ctrl->mlx5_stats_n);
+	if (!counters) {
+		DRV_LOG(WARNING, "port %u unable to allocate memory for xstats "
+				"counters",
+		     dev->data->port_id);
+		rte_errno = ENOMEM;
+		return -rte_errno;
+	}
 	ret = mlx5_read_dev_counters(dev, counters);
 	if (ret) {
 		DRV_LOG(ERR, "port %u cannot read device counters: %s",
 			dev->data->port_id, strerror(rte_errno));
-		return;
+		free(counters);
+		return ret;
 	}
-	for (i = 0; i != n; ++i)
+	for (i = 0; i != xstats_ctrl->mlx5_stats_n; ++i) {
 		xstats_ctrl->base[i] = counters[i];
+		xstats_ctrl->hw_stats[i] = 0;
+	}
+	free(counters);
+	return 0;
 }
 
 /**
-- 
2.21.0