net/mlx4_en: Do not allocate redundant TX queues when TC is disabled

Currently the number of TX queues that are allocated doesn't depend
on the number of TCs, the module always loads with max num of UP
per channel.
In order to prevent the allocation of unnecessary memory, the
module will load with minimum number of UPs per channel, and the
user will be able to control the number of TX queues per channel
by changing the number of TC to 8 using the tc command.
The variable num_up will hold the information about the current
number of UPs.
Due to the change, needed to remove the lines that set the value of
UP to be different than zero in the func "mlx4_en_select_queue",
since now the num of TX queues that are allocated is only one per channel
in default.
In order not to force the UP to be zero in case of only one TC, added
a condition before forcing it in the func "mlx4_en_fill_qp_context".

Tested:
After the module is loaded with minimum number of UP per channel, to
increase num of TCs to 8, use:
tc qdisc add dev ens8 root mqprio num_tc 8
In order to decrease the number of TCs to minimum number of UP per channel,
use:
tc qdisc del dev ens8 root

Signed-off-by: Inbar Karmy <inbark@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Cc: Tarick Bedeir <tarick@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 51 insertions, 3 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index e7f654623eab..3a291fc1780a 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -64,7 +64,7 @@ int mlx4_en_setup_tc(struct net_device *dev, u8 up)
 		return -EINVAL;
 
 	netdev_set_num_tc(dev, up);
-
+	netif_set_real_num_tx_queues(dev, priv->tx_ring_num[TX]);
 	/* Partition Tx queues evenly amongst UP's */
 	for (i = 0; i < up; i++) {
 		netdev_set_tc_queue(dev, i, priv->num_tx_rings_p_up, offset);
@@ -86,6 +86,50 @@ int mlx4_en_setup_tc(struct net_device *dev, u8 up)
 	return 0;
 }
 
+int mlx4_en_alloc_tx_queue_per_tc(struct net_device *dev, u8 tc)
+{
+	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;
+
+	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_up = (tc == 0) ? MLX4_EN_NUM_UP_LOW :
+				      MLX4_EN_NUM_UP_HIGH;
+	new_prof.tx_ring_num[TX] = new_prof.num_tx_rings_p_up *
+				   new_prof.num_up;
+	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof, true);
+	if (err)
+		goto out;
+
+	if (priv->port_up) {
+		port_up = 1;
+		mlx4_en_stop_port(dev, 1);
+	}
+
+	mlx4_en_safe_replace_resources(priv, tmp);
+	if (port_up) {
+		err = mlx4_en_start_port(dev);
+		if (err) {
+			en_err(priv, "Failed starting port for setup TC\n");
+			goto out;
+		}
+	}
+
+	err = mlx4_en_setup_tc(dev, tc);
+out:
+	mutex_unlock(&mdev->state_lock);
+	kfree(tmp);
+	return err;
+}
+
 static int __mlx4_en_setup_tc(struct net_device *dev, u32 handle,
 			      u32 chain_index, __be16 proto,
 			      struct tc_to_netdev *tc)
@@ -93,9 +137,12 @@ static int __mlx4_en_setup_tc(struct net_device *dev, u32 handle,
 	if (tc->type != TC_SETUP_MQPRIO)
 		return -EINVAL;
 
+	if (tc->mqprio->num_tc && tc->mqprio->num_tc != MLX4_EN_NUM_UP_HIGH)
+		return -EINVAL;
+
 	tc->mqprio->hw = TC_MQPRIO_HW_OFFLOAD_TCS;
 
-	return mlx4_en_setup_tc(dev, tc->mqprio->num_tc);
+	return mlx4_en_alloc_tx_queue_per_tc(dev, tc->mqprio->num_tc);
 }
 
 #ifdef CONFIG_RFS_ACCEL
@@ -2144,7 +2191,7 @@ static int mlx4_en_copy_priv(struct mlx4_en_priv *dst,
 
 	memcpy(&dst->hwtstamp_config, &prof->hwtstamp_config,
 	       sizeof(dst->hwtstamp_config));
-	dst->num_tx_rings_p_up = src->mdev->profile.num_tx_rings_p_up;
+	dst->num_tx_rings_p_up = prof->num_tx_rings_p_up;
 	dst->rx_ring_num = prof->rx_ring_num;
 	dst->flags = prof->flags;
 	dst->mdev = src->mdev;
@@ -2197,6 +2244,7 @@ static void mlx4_en_update_priv(struct mlx4_en_priv *dst,
 		dst->tx_ring[t] = src->tx_ring[t];
 		dst->tx_cq[t] = src->tx_cq[t];
 	}
+	dst->num_tx_rings_p_up = src->num_tx_rings_p_up;
 	dst->rx_ring_num = src->rx_ring_num;
 	memcpy(dst->prof, src->prof, sizeof(struct mlx4_en_port_profile));
 }