[net-next 08/10] net/mlx5e: vxlan: Use RCU for vxlan table lookup

[Saeed Mahameed]

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 <sae...@mellanox.com>
Reviewed-by: Maxim Mikityanskiy <maxi...@mellanox.com>
---
 .../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 82c766a951656..85cbc42955859 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
@@ -40,7 +40,6 @@
 
 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_in(mdev, delete_vxlan_udp_dport, in);
 }
 
-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) {
                refcount_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;
        refcount_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 (refcount_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 (IANA_VXLAN_UDP_PORT) by default */
-- 
2.26.2