From a7ac12760d59a9065826b31d6f5a2c5742ef85d5 Mon Sep 17 00:00:00 2001
From: Saeed Mahameed <saeedm@mellanox.com>
Date: Fri, 15 May 2020 17:09:05 -0700
Subject: [PATCH 14/14] net/mlx5e: vxlan: Use RCU for vxlan table lookup
Git-commit: 7a64ca862ac96d5e78a59bd57549034134ee0949
Patch-mainline: v5.9-rc1
References: git-fixes

Remove the spinlock protecting the vxlan table and use RCU instead.
This will improve performance as it will eliminate contention on data
path cores.

Fixes: b3f63c3d5e2c ("net/mlx5e: Add netdev support for VXLAN tunneling")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Acked-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 .../net/ethernet/mellanox/mlx5/core/lib/vxlan.c    | 65 +++++++++-------------
 1 file changed, 27 insertions(+), 38 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
index 9a8fd762167b..9d30adbe1657 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
@@ -38,7 +38,6 @@
 
 struct mlx5_vxlan {
 	struct mlx5_core_dev		*mdev;
-	spinlock_t			lock; /* protect vxlan table */
 	/* max_num_ports is usuallly 4, 16 buckets is more than enough */
 	DECLARE_HASHTABLE(htable, 4);
 	int				num_ports;
@@ -78,45 +77,46 @@ static int mlx5_vxlan_core_del_port_cmd(struct mlx5_core_dev *mdev, u16 port)
 	return mlx5_cmd_exec(mdev, in, sizeof(in), out, sizeof(out));
 }
 
-static struct mlx5_vxlan_port*
-mlx5_vxlan_lookup_port_locked(struct mlx5_vxlan *vxlan, u16 port)
+struct mlx5_vxlan_port *mlx5_vxlan_lookup_port(struct mlx5_vxlan *vxlan, u16 port)
 {
-	struct mlx5_vxlan_port *vxlanp;
+	struct mlx5_vxlan_port *retptr = NULL, *vxlanp;
 
-	hash_for_each_possible(vxlan->htable, vxlanp, hlist, port) {
-		if (vxlanp->udp_port == port)
-			return vxlanp;
-	}
+	if (!mlx5_vxlan_allowed(vxlan))
+		return NULL;
 
-	return NULL;
+	rcu_read_lock();
+	hash_for_each_possible_rcu(vxlan->htable, vxlanp, hlist, port)
+		if (vxlanp->udp_port == port) {
+			retptr = vxlanp;
+			break;
+		}
+	rcu_read_unlock();
+
+	return retptr;
 }
 
-struct mlx5_vxlan_port *mlx5_vxlan_lookup_port(struct mlx5_vxlan *vxlan, u16 port)
+static struct mlx5_vxlan_port *vxlan_lookup_port(struct mlx5_vxlan *vxlan, u16 port)
 {
 	struct mlx5_vxlan_port *vxlanp;
 
-	if (!mlx5_vxlan_allowed(vxlan))
-		return NULL;
-
-	spin_lock_bh(&vxlan->lock);
-	vxlanp = mlx5_vxlan_lookup_port_locked(vxlan, port);
-	spin_unlock_bh(&vxlan->lock);
-
-	return vxlanp;
+	hash_for_each_possible(vxlan->htable, vxlanp, hlist, port)
+		if (vxlanp->udp_port == port)
+			return vxlanp;
+	return NULL;
 }
 
 int mlx5_vxlan_add_port(struct mlx5_vxlan *vxlan, u16 port)
 {
 	struct mlx5_vxlan_port *vxlanp;
-	int ret = -ENOSPC;
+	int ret = 0;
 
-	vxlanp = mlx5_vxlan_lookup_port(vxlan, port);
+	mutex_lock(&vxlan->sync_lock);
+	vxlanp = vxlan_lookup_port(vxlan, port);
 	if (vxlanp) {
 		atomic_inc(&vxlanp->refcount);
-		return 0;
+		goto unlock;
 	}
 
-	mutex_lock(&vxlan->sync_lock);
 	if (vxlan->num_ports >= mlx5_vxlan_max_udp_ports(vxlan->mdev)) {
 		mlx5_core_info(vxlan->mdev,
 			       "UDP port (%d) not offloaded, max number of UDP ports (%d) are already offloaded\n",
@@ -138,9 +138,7 @@ int mlx5_vxlan_add_port(struct mlx5_vxlan *vxlan, u16 port)
 	vxlanp->udp_port = port;
 	atomic_set(&vxlanp->refcount, 1);
 
-	spin_lock_bh(&vxlan->lock);
-	hash_add(vxlan->htable, &vxlanp->hlist, port);
-	spin_unlock_bh(&vxlan->lock);
+	hash_add_rcu(vxlan->htable, &vxlanp->hlist, port);
 
 	vxlan->num_ports++;
 	mutex_unlock(&vxlan->sync_lock);
@@ -157,34 +155,26 @@ int mlx5_vxlan_add_port(struct mlx5_vxlan *vxlan, u16 port)
 int mlx5_vxlan_del_port(struct mlx5_vxlan *vxlan, u16 port)
 {
 	struct mlx5_vxlan_port *vxlanp;
-	bool remove = false;
 	int ret = 0;
 
 	mutex_lock(&vxlan->sync_lock);
 
-	spin_lock_bh(&vxlan->lock);
-	vxlanp = mlx5_vxlan_lookup_port_locked(vxlan, port);
+	vxlanp = vxlan_lookup_port(vxlan, port);
 	if (!vxlanp) {
 		ret = -ENOENT;
 		goto out_unlock;
 	}
 
 	if (atomic_dec_and_test(&vxlanp->refcount)) {
-		hash_del(&vxlanp->hlist);
-		remove = true;
-	}
-
-out_unlock:
-	spin_unlock_bh(&vxlan->lock);
-
-	if (remove) {
+		hash_del_rcu(&vxlanp->hlist);
+		synchronize_rcu();
 		mlx5_vxlan_core_del_port_cmd(vxlan->mdev, port);
 		kfree(vxlanp);
 		vxlan->num_ports--;
 	}
 
+out_unlock:
 	mutex_unlock(&vxlan->sync_lock);
-
 	return ret;
 }
 
@@ -201,7 +191,6 @@ struct mlx5_vxlan *mlx5_vxlan_create(struct mlx5_core_dev *mdev)
 
 	vxlan->mdev = mdev;
 	mutex_init(&vxlan->sync_lock);
-	spin_lock_init(&vxlan->lock);
 	hash_init(vxlan->htable);
 
 	/* Hardware adds 4789 by default */
-- 
2.16.4