Subject: [PATCH 28/33] net/mlx5e: Prevent possible races in VXLAN control flow

From: Gal Pressman <[email-masked]>
Date: Mon, 4 Dec 2017 09:57:43 +0200

[ Upstream commit 0c1cc8b2215f5122ca614b5adca60346018758c3 ]

When calling add/remove VXLAN port, a lock must be held in order to
prevent race scenarios when more than one add/remove happens at the
same time.
Fix by holding our state_lock (mutex) as done by all other parts of the
driver.
Note that the spinlock protecting the radix-tree is still needed in
order to synchronize radix-tree access from softirq context.

Fixes: b3f63c3d5e2c ("net/mlx5e: Add netdev support for VXLAN tunneling")
Signed-off-by: Gal Pressman <[email-masked]>
Signed-off-by: Saeed Mahameed <[email-masked]>
---
 drivers/net/ethernet/mellanox/mlx5/core/vxlan.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c b/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c
index 25f7823..2f74953 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/vxlan.c
@@ -88,6 +88,7 @@ static void mlx5e_vxlan_add_port(struct work_struct *work)
 	struct mlx5e_vxlan *vxlan;
 	int err;
 
+	mutex_lock(&priv->state_lock);
 	vxlan = mlx5e_vxlan_lookup_port(priv, port);
 	if (vxlan) {
 		atomic_inc(&vxlan->refcount);
@@ -117,6 +118,7 @@ static void mlx5e_vxlan_add_port(struct work_struct *work)
 err_delete_port:
 	mlx5e_vxlan_core_del_port_cmd(priv->mdev, port);
 free_work:
+	mutex_unlock(&priv->state_lock);
 	kfree(vxlan_work);
 }
 
@@ -130,6 +132,7 @@ static void mlx5e_vxlan_del_port(struct work_struct *work)
 	struct mlx5e_vxlan *vxlan;
 	bool remove = false;
 
+	mutex_lock(&priv->state_lock);
 	spin_lock_bh(&vxlan_db->lock);
 	vxlan = radix_tree_lookup(&vxlan_db->tree, port);
 	if (!vxlan)
@@ -147,6 +150,7 @@ static void mlx5e_vxlan_del_port(struct work_struct *work)
 		mlx5e_vxlan_core_del_port_cmd(priv->mdev, port);
 		kfree(vxlan);
 	}
+	mutex_unlock(&priv->state_lock);
 	kfree(vxlan_work);
 }
 
-- 
2.9.5