On Mon, Jan 30, 2017 at 07:18:28PM +0200, Tariq Toukan wrote:

Hi Martin,

Thanks for your patch.

It looks good to me, in general.
I just have one small comment below.

Thanks for your feedback and sorry for the delay.

On 28/01/2017 9:40 AM, Martin KaFai Lau wrote:

quoted

If the rx-queues ever get re-initialized (e.g. by changing the
number of rx-queues with ethtool -L), the existing xdp_prog becomes
inactive.

The bug is that the xdp_prog ptr has not been carried over from
the old rx-queues to the new rx-queues

Fixes: 47a38e155037 ("net/mlx4_en: add support for fast rx drop bpf program")
Signed-off-by: Martin KaFai Lau <redacted>
---

...

quoted

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index 761f8b12399c..f4179086b3c6 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c

@@ -2184,23 +2184,57 @@ static void mlx4_en_update_priv(struct mlx4_en_priv *dst,
  int mlx4_en_try_alloc_resources(struct mlx4_en_priv *priv,
  				struct mlx4_en_priv *tmp,
-				struct mlx4_en_port_profile *prof)
+				struct mlx4_en_port_profile *prof,
+				bool carry_xdp_prog)
  {
-	int t;
+	struct bpf_prog *xdp_prog = NULL;
+	int err;
+	int i;
  	mlx4_en_copy_priv(tmp, priv, prof);
+	if (carry_xdp_prog) {
+		/* All rx_rings has the same xdp_prog.  Pick the first one */
+		xdp_prog = rcu_dereference_protected(
+			priv->rx_ring[0]->xdp_prog,
+			lockdep_is_held(&priv->mdev->state_lock));
+
+		if (xdp_prog) {
+			xdp_prog = bpf_prog_add(xdp_prog, tmp->rx_ring_num);
+			if (IS_ERR(xdp_prog)) {
+				err = PTR_ERR(xdp_prog);
+				xdp_prog = NULL;
+				goto err_free;
+			}
+		}
+	}

Why do you prefer dealing with xdp_prog in two stages? You can handle it all
at once, after "mlx4_en_alloc_resources()" succeeds.

If bpf_prog_add() did fail, resources allocated for tmp had to
be freed.  I was thinking it is not safe to call mlx4_en_free_resources()
at this point.  Since your feedback, I took another look and re-read the
'goto err' path in mlx4_en_alloc_resources(), I realized we can use
mlx4_en_free_resources() here for the bpf_prog_add() error case.  Hence,
agree with your suggestion.

A side note though:
after taking another look at mlx4_en_free_resources(), I might have found
another issue.  I need to run some tests to confirm first to avoid any false
alarm.

I will post v2.

Thanks,
--Martin

quoted

+
  	if (mlx4_en_alloc_resources(tmp)) {
  		en_warn(priv,
  			"%s: Resource allocation failed, using previous configuration\n",
  			__func__);
-		for (t = 0; t < MLX4_EN_NUM_TX_TYPES; t++) {
-			kfree(tmp->tx_ring[t]);
-			kfree(tmp->tx_cq[t]);
-		}
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto err_free;
+	}
+
+	if (xdp_prog) {
+		for (i = 0; i < tmp->rx_ring_num; i++)
+			rcu_assign_pointer(tmp->rx_ring[i]->xdp_prog,
+					   xdp_prog);
  	}
+
  	return 0;
+
+err_free:
+	if (xdp_prog)
+		bpf_prog_sub(xdp_prog, tmp->rx_ring_num);
+
+	for (i = 0; i < MLX4_EN_NUM_TX_TYPES; i++) {
+		kfree(tmp->tx_ring[i]);
+		kfree(tmp->tx_cq[i]);
+	}
+
+	return err;
  }
  void mlx4_en_safe_replace_resources(struct mlx4_en_priv *priv,

Regards,
Tariq Toukan.