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net/mlx5e: vxlan: Use RCU for vxlan table lookup
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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: b3f63c3 ("net/mlx5e: Add netdev support for VXLAN tunneling")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Maxim Mikityanskiy <maximmi@mellanox.com>
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Saeed Mahameed committed Jun 25, 2020
1 parent 185901c commit 7a64ca8
Showing 1 changed file with 27 additions and 38 deletions.
65 changes: 27 additions & 38 deletions drivers/net/ethernet/mellanox/mlx5/core/lib/vxlan.c
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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",
Expand All @@ -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);
Expand All @@ -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;
}

Expand All @@ -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 */
Expand Down

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