[dpdk-dev] [PATCH 2/2] net/mlx5: fix extended statistics wrong number

[Shahaf Shuler <shahafs@mellanox.com>]

The number of extended statistics counters is queried through ETHTOOL.
ETHTOOL provides a different number when the link is up or down.
Since extended statistics query occurs at device start,
segmentation fault might happen when changing the link state before and
after the device start.

this commit address this issue, and query the number of statistics
before every call to ETHTOOL.

Fixes: a4193ae3bc4f ("net/mlx5: support extended statistics")
CC: stable@dpdk.org

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
---
 drivers/net/mlx5/mlx5_stats.c | 48 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 39 insertions(+), 9 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_stats.c b/drivers/net/mlx5/mlx5_stats.c
index 0c80e4f..60ffbaa 100644
--- a/drivers/net/mlx5/mlx5_stats.c
+++ b/drivers/net/mlx5/mlx5_stats.c
@@ -166,6 +166,29 @@ struct mlx5_counter_ctrl {
 }
 
 /**
+ * Query the number of statistics provided by ETHTOOL.
+ *
+ * @param priv
+ *   Pointer to private structure.
+ *
+ * @return
+ *   Number of statistics on success, -1 on error.
+ */
+static int
+priv_ethtool_get_stats_n(struct priv *priv) {
+	struct ethtool_drvinfo drvinfo;
+	struct ifreq ifr;
+
+	drvinfo.cmd = ETHTOOL_GDRVINFO;
+	ifr.ifr_data = (caddr_t)&drvinfo;
+	if (priv_ifreq(priv, SIOCETHTOOL, &ifr) != 0) {
+		WARN("unable to query number of statistics");
+		return -1;
+	}
+	return drvinfo.n_stats;
+}
+
+/**
  * Init the structures to read device counters.
  *
  * @param priv
@@ -178,19 +201,11 @@ struct mlx5_counter_ctrl {
 	unsigned int i;
 	unsigned int j;
 	struct ifreq ifr;
-	struct ethtool_drvinfo drvinfo;
 	struct ethtool_gstrings *strings = NULL;
 	unsigned int dev_stats_n;
 	unsigned int str_sz;
 
-	/* How many statistics are available. */
-	drvinfo.cmd = ETHTOOL_GDRVINFO;
-	ifr.ifr_data = (caddr_t)&drvinfo;
-	if (priv_ifreq(priv, SIOCETHTOOL, &ifr) != 0) {
-		WARN("unable to get driver info");
-		return;
-	}
-	dev_stats_n = drvinfo.n_stats;
+	dev_stats_n = priv_ethtool_get_stats_n(priv);
 	if (dev_stats_n < 1) {
 		WARN("no extended statistics available");
 		return;
@@ -410,7 +425,15 @@ struct mlx5_counter_ctrl {
 	int ret = xstats_n;
 
 	if (n >= xstats_n && stats) {
+		struct mlx5_xstats_ctrl *xstats_ctrl = &priv->xstats_ctrl;
+		int stats_n;
+
 		priv_lock(priv);
+		stats_n = priv_ethtool_get_stats_n(priv);
+		if (stats_n < 0)
+			return -1;
+		if (xstats_ctrl->stats_n != stats_n)
+			priv_xstats_init(priv);
 		ret = priv_xstats_get(priv, stats);
 		priv_unlock(priv);
 	}
@@ -427,8 +450,15 @@ struct mlx5_counter_ctrl {
 mlx5_xstats_reset(struct rte_eth_dev *dev)
 {
 	struct priv *priv = mlx5_get_priv(dev);
+	struct mlx5_xstats_ctrl *xstats_ctrl = &priv->xstats_ctrl;
+	int stats_n;
 
 	priv_lock(priv);
+	stats_n = priv_ethtool_get_stats_n(priv);
+	if (stats_n < 0)
+		return;
+	if (xstats_ctrl->stats_n != stats_n)
+		priv_xstats_init(priv);
 	priv_xstats_reset(priv);
 	priv_unlock(priv);
 }
-- 
1.8.3.1