[v2 Patch 2/2] mlx4: add dynamic LRO disable support

[Amerigo Wang <amwang@redhat.com>]

This patch adds dynamic LRO diable support for mlx4 net driver.
It also fixes a bug of mlx4, which checks NETIF_F_LRO flag in rx
path without rtnl lock.

I don't have mlx4 card, so only did compiling test. Anyone who wants
to test this is more than welcome.

This is based on Neil's initial work too.

Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Neil Horman <nhorman@redhat.com>
Acked-by: Neil Horman <nhorman@redhat.com>
Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>

---

diff --git a/drivers/net/mlx4/en_ethtool.c b/drivers/net/mlx4/en_ethtool.c
index d5afd03..2c77805 100644
--- a/drivers/net/mlx4/en_ethtool.c
+++ b/drivers/net/mlx4/en_ethtool.c
@@ -387,6 +387,37 @@ static void mlx4_en_get_ringparam(struct net_device *dev,
 	param->tx_pending = mdev->profile.prof[priv->port].tx_ring_size;
 }
 
+static int mlx4_ethtool_op_set_flags(struct net_device *dev, u32 data)
+{
+	struct mlx4_en_priv *priv = netdev_priv(dev);
+	struct mlx4_en_dev *mdev = priv->mdev;
+	int rc = 0;
+	int changed = 0;
+
+	if (data & ETH_FLAG_LRO) {
+		if (!(dev->features & NETIF_F_LRO)) {
+			dev->features |= NETIF_F_LRO;
+			changed = 1;
+			mdev->profile.num_lro = min_t(int, num_lro , MLX4_EN_MAX_LRO_DESCRIPTORS);
+		}
+	} else if (dev->features & NETIF_F_LRO) {
+		dev->features &= ~NETIF_F_LRO;
+		changed = 1;
+		mdev->profile.num_lro = 0;
+	}
+
+	if (changed && netif_running(dev)) {
+		mutex_lock(&mdev->state_lock);
+		mlx4_en_stop_port(dev);
+		rc = mlx4_en_start_port(dev);
+		if (rc)
+			en_err(priv, "Failed to restart port\n");
+		mutex_unlock(&mdev->state_lock);
+	}
+
+	return rc;
+}
+
 const struct ethtool_ops mlx4_en_ethtool_ops = {
 	.get_drvinfo = mlx4_en_get_drvinfo,
 	.get_settings = mlx4_en_get_settings,
@@ -415,7 +446,7 @@ const struct ethtool_ops mlx4_en_ethtool_ops = {
 	.get_ringparam = mlx4_en_get_ringparam,
 	.set_ringparam = mlx4_en_set_ringparam,
 	.get_flags = ethtool_op_get_flags,
-	.set_flags = ethtool_op_set_flags,
+	.set_flags = mlx4_ethtool_op_set_flags,
 };
 
 
diff --git a/drivers/net/mlx4/en_main.c b/drivers/net/mlx4/en_main.c
index cbabf14..4ef42e2 100644
--- a/drivers/net/mlx4/en_main.c
+++ b/drivers/net/mlx4/en_main.c
@@ -70,8 +70,9 @@ MLX4_EN_PARM_INT(rss_xor, 0, "Use XOR hash function for RSS");
 MLX4_EN_PARM_INT(rss_mask, 0xf, "RSS hash type bitmask");
 
 /* Number of LRO sessions per Rx ring (rounded up to a power of two) */
-MLX4_EN_PARM_INT(num_lro, MLX4_EN_MAX_LRO_DESCRIPTORS,
-		 "Number of LRO sessions per ring or disabled (0)");
+unsigned int num_lro = MLX4_EN_MAX_LRO_DESCRIPTORS;
+module_param(num_lro , uint, 0444);
+MODULE_PARM_DESC(num_lro, "Number of LRO sessions per ring or disabled (0)");
 
 /* Priority pausing */
 MLX4_EN_PARM_INT(pfctx, 0, "Priority based Flow Control policy on TX[7:0]."
diff --git a/drivers/net/mlx4/mlx4_en.h b/drivers/net/mlx4/mlx4_en.h
index b55e46c..bbac975 100644
--- a/drivers/net/mlx4/mlx4_en.h
+++ b/drivers/net/mlx4/mlx4_en.h
@@ -568,4 +568,6 @@ int mlx4_en_DUMP_ETH_STATS(struct mlx4_en_dev *mdev, u8 port, u8 reset);
  * Globals
  */
 extern const struct ethtool_ops mlx4_en_ethtool_ops;
+
+extern unsigned int num_lro;
 #endif