[PATCH 4.9 35/60] net/mlx5e: Modify TIRs hash only when its needed

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gal Pressman <galp@xxxxxxxxxxxx>

commit 1d3398facd08a7fd4202f269317a95668eb880b9 upstream.

We don't need to modify our TIRs unless the user requested a change in
the hash function/key, for example when changing indirection only.

Tested:
 # Modify TIRs hash is needed
ethtool -X ethX hkey  <new key>
ethtool -X ethX hfunc <new func>

 # Modify TIRs hash is not needed
ethtool -X ethX equal <new indirection table>

All cases are verified with TCP Multi-Stream traffic over IPv4 & IPv6.

Fixes: bdfc028de1b3 ("net/mlx5e: Fix ethtool RX hash func configuration change")
Signed-off-by: Gal Pressman <galp@xxxxxxxxxxxx>
Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -991,6 +991,7 @@ static int mlx5e_set_rxfh(struct net_dev
 {
 	struct mlx5e_priv *priv = netdev_priv(dev);
 	int inlen = MLX5_ST_SZ_BYTES(modify_tir_in);
+	bool hash_changed = false;
 	void *in;
 
 	if ((hfunc != ETH_RSS_HASH_NO_CHANGE) &&
@@ -1012,14 +1013,21 @@ static int mlx5e_set_rxfh(struct net_dev
 		mlx5e_redirect_rqt(priv, rqtn, MLX5E_INDIR_RQT_SIZE, 0);
 	}
 
-	if (key)
+	if (hfunc != ETH_RSS_HASH_NO_CHANGE &&
+	    hfunc != priv->params.rss_hfunc) {
+		priv->params.rss_hfunc = hfunc;
+		hash_changed = true;
+	}
+
+	if (key) {
 		memcpy(priv->params.toeplitz_hash_key, key,
 		       sizeof(priv->params.toeplitz_hash_key));
+		hash_changed = hash_changed ||
+			       priv->params.rss_hfunc == ETH_RSS_HASH_TOP;
+	}
 
-	if (hfunc != ETH_RSS_HASH_NO_CHANGE)
-		priv->params.rss_hfunc = hfunc;
-
-	mlx5e_modify_tirs_hash(priv, in, inlen);
+	if (hash_changed)
+		mlx5e_modify_tirs_hash(priv, in, inlen);
 
 	mutex_unlock(&priv->state_lock);