netdev - [net 10/14] net/mlx5e: Add refcount to VXLAN structure

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Date:   Wed, 20 Dec 2017 00:24:52 +0200
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Gal Pressman <galp@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net 10/14] net/mlx5e: Add refcount to VXLAN structure

From: Gal Pressman <galp@...lanox.com>

A refcount mechanism must be implemented in order to prevent unwanted
scenarios such as:
- Open an IPv4 VXLAN interface
- Open an IPv6 VXLAN interface (different socket)
- Remove one of the interfaces

With current implementation, the UDP port will be removed from our VXLAN
database and turn off the offloads for the other interface, which is
still active.
The reference count mechanism will only allow UDP port removals once all
consumers are gone.

Fixes: b3f63c3d5e2c ("net/mlx5e: Add netdev support for VXLAN tunneling")
Signed-off-by: Gal Pressman <galp@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/vxlan.c | 50 +++++++++++++------------
 drivers/net/ethernet/mellanox/mlx5/core/vxlan.h |  1 +
 2 files changed, 28 insertions(+), 23 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c b/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c
index f8238275759f..25f782344667 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c
@@ -88,8 +88,11 @@ static void mlx5e_vxlan_add_port(struct work_struct *work)
 	struct mlx5e_vxlan *vxlan;
 	int err;
 
-	if (mlx5e_vxlan_lookup_port(priv, port))
+	vxlan = mlx5e_vxlan_lookup_port(priv, port);
+	if (vxlan) {
+		atomic_inc(&vxlan->refcount);
 		goto free_work;
+	}
 
 	if (mlx5e_vxlan_core_add_port_cmd(priv->mdev, port))
 		goto free_work;
@@ -99,6 +102,7 @@ static void mlx5e_vxlan_add_port(struct work_struct *work)
 		goto err_delete_port;
 
 	vxlan->udp_port = port;
+	atomic_set(&vxlan->refcount, 1);
 
 	spin_lock_bh(&vxlan_db->lock);
 	err = radix_tree_insert(&vxlan_db->tree, vxlan->udp_port, vxlan);
@@ -116,32 +120,33 @@ static void mlx5e_vxlan_add_port(struct work_struct *work)
 	kfree(vxlan_work);
 }
 
-static void __mlx5e_vxlan_core_del_port(struct mlx5e_priv *priv, u16 port)
+static void mlx5e_vxlan_del_port(struct work_struct *work)
 {
+	struct mlx5e_vxlan_work *vxlan_work =
+		container_of(work, struct mlx5e_vxlan_work, work);
+	struct mlx5e_priv *priv         = vxlan_work->priv;
 	struct mlx5e_vxlan_db *vxlan_db = &priv->vxlan;
+	u16 port = vxlan_work->port;
 	struct mlx5e_vxlan *vxlan;
+	bool remove = false;
 
 	spin_lock_bh(&vxlan_db->lock);
-	vxlan = radix_tree_delete(&vxlan_db->tree, port);
-	spin_unlock_bh(&vxlan_db->lock);
-
+	vxlan = radix_tree_lookup(&vxlan_db->tree, port);
 	if (!vxlan)
-		return;
-
-	mlx5e_vxlan_core_del_port_cmd(priv->mdev, vxlan->udp_port);
-
-	kfree(vxlan);
-}
+		goto out_unlock;
 
-static void mlx5e_vxlan_del_port(struct work_struct *work)
-{
-	struct mlx5e_vxlan_work *vxlan_work =
-		container_of(work, struct mlx5e_vxlan_work, work);
-	struct mlx5e_priv *priv = vxlan_work->priv;
-	u16 port = vxlan_work->port;
+	if (atomic_dec_and_test(&vxlan->refcount)) {
+		radix_tree_delete(&vxlan_db->tree, port);
+		remove = true;
+	}
 
-	__mlx5e_vxlan_core_del_port(priv, port);
+out_unlock:
+	spin_unlock_bh(&vxlan_db->lock);
 
+	if (remove) {
+		mlx5e_vxlan_core_del_port_cmd(priv->mdev, port);
+		kfree(vxlan);
+	}
 	kfree(vxlan_work);
 }
 
@@ -171,12 +176,11 @@ void mlx5e_vxlan_cleanup(struct mlx5e_priv *priv)
 	struct mlx5e_vxlan *vxlan;
 	unsigned int port = 0;
 
-	spin_lock_bh(&vxlan_db->lock);
+	/* Lockless since we are the only radix-tree consumers, wq is disabled */
 	while (radix_tree_gang_lookup(&vxlan_db->tree, (void **)&vxlan, port, 1)) {
 		port = vxlan->udp_port;
-		spin_unlock_bh(&vxlan_db->lock);
-		__mlx5e_vxlan_core_del_port(priv, (u16)port);
-		spin_lock_bh(&vxlan_db->lock);
+		radix_tree_delete(&vxlan_db->tree, port);
+		mlx5e_vxlan_core_del_port_cmd(priv->mdev, port);
+		kfree(vxlan);
 	}
-	spin_unlock_bh(&vxlan_db->lock);
 }
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/vxlan.h b/drivers/net/ethernet/mellanox/mlx5/core/vxlan.h
index 5def12c048e3..5ef6ae7d568a 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/vxlan.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/vxlan.h
@@ -36,6 +36,7 @@
 #include "en.h"
 
 struct mlx5e_vxlan {
+	atomic_t refcount;
 	u16 udp_port;
 };
 
-- 
2.13.0