net/mlx4_en: Add resilience in low memory systems

This patch fixes the lost of Ethernet port on low memory system,
when driver frees its resources and fails to allocate new resources.
Issue could happen while changing number of channels, rings size or
changing the timestamp configuration.
This fix is necessary because of removing vmap use in the code.
When vmap was in use driver could allocate non-contiguous memory
and make it contiguous with vmap. Now it could fail to allocate
a large chunk of contiguous memory and lose the port.
Current code tries to allocate new resources and then upon success
frees the old resources.

Fixes: 73898db04301 ('net/mlx4: Avoid wrong virtual mappings')
Signed-off-by: Eugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 22 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
index fc95affaf76b..44cf16d01f42 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
@@ -1042,6 +1042,8 @@ static int mlx4_en_set_ringparam(struct net_device *dev,
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	struct mlx4_en_dev *mdev = priv->mdev;
+	struct mlx4_en_port_profile new_prof;
+	struct mlx4_en_priv *tmp;
 	u32 rx_size, tx_size;
 	int port_up = 0;
 	int err = 0;
@@ -1061,22 +1063,25 @@ static int mlx4_en_set_ringparam(struct net_device *dev,
 	    tx_size == priv->tx_ring[0]->size)
 		return 0;
 
+	tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
 	mutex_lock(&mdev->state_lock);
+	memcpy(&new_prof, priv->prof, sizeof(struct mlx4_en_port_profile));
+	new_prof.tx_ring_size = tx_size;
+	new_prof.rx_ring_size = rx_size;
+	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof);
+	if (err)
+		goto out;
+
 	if (priv->port_up) {
 		port_up = 1;
 		mlx4_en_stop_port(dev, 1);
 	}
 
-	mlx4_en_free_resources(priv);
-
-	priv->prof->tx_ring_size = tx_size;
-	priv->prof->rx_ring_size = rx_size;
+	mlx4_en_safe_replace_resources(priv, tmp);
 
-	err = mlx4_en_alloc_resources(priv);
-	if (err) {
-		en_err(priv, "Failed reallocating port resources\n");
-		goto out;
-	}
 	if (port_up) {
 		err = mlx4_en_start_port(dev);
 		if (err)
@@ -1084,8 +1089,8 @@ static int mlx4_en_set_ringparam(struct net_device *dev,
 	}
 
 	err = mlx4_en_moderation_update(priv);
-
 out:
+	kfree(tmp);
 	mutex_unlock(&mdev->state_lock);
 	return err;
 }
@@ -1714,6 +1719,8 @@ static int mlx4_en_set_channels(struct net_device *dev,
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	struct mlx4_en_dev *mdev = priv->mdev;
+	struct mlx4_en_port_profile new_prof;
+	struct mlx4_en_priv *tmp;
 	int port_up = 0;
 	int err = 0;
 
@@ -1723,23 +1730,26 @@ static int mlx4_en_set_channels(struct net_device *dev,
 	    !channel->tx_count || !channel->rx_count)
 		return -EINVAL;
 
+	tmp = kzalloc(sizeof(*tmp), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
 	mutex_lock(&mdev->state_lock);
+	memcpy(&new_prof, priv->prof, sizeof(struct mlx4_en_port_profile));
+	new_prof.num_tx_rings_p_up = channel->tx_count;
+	new_prof.tx_ring_num = channel->tx_count * MLX4_EN_NUM_UP;
+	new_prof.rx_ring_num = channel->rx_count;
+
+	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof);
+	if (err)
+		goto out;
+
 	if (priv->port_up) {
 		port_up = 1;
 		mlx4_en_stop_port(dev, 1);
 	}
 
-	mlx4_en_free_resources(priv);
-
-	priv->num_tx_rings_p_up = channel->tx_count;
-	priv->tx_ring_num = channel->tx_count * MLX4_EN_NUM_UP;
-	priv->rx_ring_num = channel->rx_count;
-
-	err = mlx4_en_alloc_resources(priv);
-	if (err) {
-		en_err(priv, "Failed reallocating port resources\n");
-		goto out;
-	}
+	mlx4_en_safe_replace_resources(priv, tmp);
 
 	netif_set_real_num_tx_queues(dev, priv->tx_ring_num);
 	netif_set_real_num_rx_queues(dev, priv->rx_ring_num);
@@ -1757,8 +1767,8 @@ static int mlx4_en_set_channels(struct net_device *dev,
 	}
 
 	err = mlx4_en_moderation_update(priv);
-
 out:
+	kfree(tmp);
 	mutex_unlock(&mdev->state_lock);
 	return err;
 }