[PATCH net V1] net/mlx4_en: Prevent setting invalid RSS hash function

[PATCH net V1] net/mlx4_en: Prevent setting invalid RSS hash function

[Amir Vadai]

mlx4_en_check_rxfh_func() was checking for hardware support before
setting a known RSS hash function, but didn't do any check before
setting unknown RSS hash function. Need to make it fail on such values.
In this occasion, moved the actual setting of the new value from the
check function into mlx4_en_set_rxfh().

Fixes: 947cbb0 ("net/mlx4_en: Support for configurable RSS hash function")
Signed-off-by: Amir Vadai <amirv@mellanox.com>
---
Hi Dave,

Changes from V0:
- Removed patch that changed hash function field into values instead of bit flags

This patch is left as is, since it works the same for hash function as a bit flag.
It will fail the operation if a combination of flags is set or an unknown function.

Applied and tested over commit 2ea2f62 ("net: fix crash in build_skb()")

Please push this patch to 3.19.y and 4.0.y since the bug was interduced in 3.19

Thanks,
Amir

 drivers/net/ethernet/mellanox/mlx4/en_ethtool.c | 29 ++++++++++++++-----------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
index 3f44e2b..a2ddf3d 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
@@ -1102,20 +1102,21 @@ static int mlx4_en_check_rxfh_func(struct net_device *dev, u8 hfunc)
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 
 	/* check if requested function is supported by the device */
-	if ((hfunc == ETH_RSS_HASH_TOP &&
-	     !(priv->mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_RSS_TOP)) ||
-	    (hfunc == ETH_RSS_HASH_XOR &&
-	     !(priv->mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_RSS_XOR)))
-		return -EINVAL;
+	if (hfunc == ETH_RSS_HASH_TOP) {
+		if (!(priv->mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_RSS_TOP))
+			return -EINVAL;
+		if (!(dev->features & NETIF_F_RXHASH))
+			en_warn(priv, "Toeplitz hash function should be used in conjunction with RX hashing for optimal performance\n");
+		return 0;
+	} else if (hfunc == ETH_RSS_HASH_XOR) {
+		if (!(priv->mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_RSS_XOR))
+			return -EINVAL;
+		if (dev->features & NETIF_F_RXHASH)
+			en_warn(priv, "Enabling both XOR Hash function and RX Hashing can limit RPS functionality\n");
+		return 0;
+	}
 
-	priv->rss_hash_fn = hfunc;
-	if (hfunc == ETH_RSS_HASH_TOP && !(dev->features & NETIF_F_RXHASH))
-		en_warn(priv,
-			"Toeplitz hash function should be used in conjunction with RX hashing for optimal performance\n");
-	if (hfunc == ETH_RSS_HASH_XOR && (dev->features & NETIF_F_RXHASH))
-		en_warn(priv,
-			"Enabling both XOR Hash function and RX Hashing can limit RPS functionality\n");
-	return 0;
+	return -EINVAL;
 }
 
 static int mlx4_en_get_rxfh(struct net_device *dev, u32 *ring_index, u8 *key,
@@ -1189,6 +1190,8 @@ static int mlx4_en_set_rxfh(struct net_device *dev, const u32 *ring_index,
 		priv->prof->rss_rings = rss_rings;
 	if (key)
 		memcpy(priv->rss_key, key, MLX4_EN_RSS_KEY_SIZE);
+	if (hfunc !=  ETH_RSS_HASH_NO_CHANGE)
+		priv->rss_hash_fn = hfunc;
 
 	if (port_up) {
 		err = mlx4_en_start_port(dev);
-- 
1.9.3

Re: [PATCH net V1] net/mlx4_en: Prevent setting invalid RSS hash function

[David Miller]

From: Amir Vadai <amirv@mellanox.com>
Date: Mon, 27 Apr 2015 13:40:56 +0300

> mlx4_en_check_rxfh_func() was checking for hardware support before
> setting a known RSS hash function, but didn't do any check before
> setting unknown RSS hash function. Need to make it fail on such values.
> In this occasion, moved the actual setting of the new value from the
> check function into mlx4_en_set_rxfh().
> 
> Fixes: 947cbb0 ("net/mlx4_en: Support for configurable RSS hash function")
> Signed-off-by: Amir Vadai <amirv@mellanox.com>

Applied and queued up for -stable, thanks.