datapath: change the data type of error status to atomic_long_t

Change the date type of error status from u64 to atomic_long_t, and use atomic
operation, then remove the lock which is used to protect the error status.

The operation of atomic maybe faster than spin lock.

Cc: Pravin Shelar <pshelar@nicira.com>
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>

datapath/vport.c

@@ -151,8 +151,6 @@ struct vport *ovs_vport_alloc(int priv_size, const struct vport_ops *ops,
 		return ERR_PTR(-ENOMEM);
 	}
 
-	spin_lock_init(&vport->stats_lock);
-
 	return vport;
 }
 
@@ -266,14 +264,10 @@ void ovs_vport_get_stats(struct vport *vport, struct ovs_vport_stats *stats)
 	 * netdev-stats can be directly read over netlink-ioctl.
 	 */
 
-	spin_lock_bh(&vport->stats_lock);
-
-	stats->rx_errors	= vport->err_stats.rx_errors;
-	stats->tx_errors	= vport->err_stats.tx_errors;
-	stats->tx_dropped	= vport->err_stats.tx_dropped;
-	stats->rx_dropped	= vport->err_stats.rx_dropped;
-
-	spin_unlock_bh(&vport->stats_lock);
+	stats->rx_errors  = atomic_long_read(&vport->err_stats.rx_errors);
+	stats->tx_errors  = atomic_long_read(&vport->err_stats.tx_errors);
+	stats->tx_dropped = atomic_long_read(&vport->err_stats.tx_dropped);
+	stats->rx_dropped = atomic_long_read(&vport->err_stats.rx_dropped);
 
 	stats->rx_bytes		= 0;
 	stats->rx_packets	= 0;
@@ -516,27 +510,23 @@ int ovs_vport_send(struct vport *vport, struct sk_buff *skb)
 static void ovs_vport_record_error(struct vport *vport,
 				   enum vport_err_type err_type)
 {
-	spin_lock(&vport->stats_lock);
-
 	switch (err_type) {
 	case VPORT_E_RX_DROPPED:
-		vport->err_stats.rx_dropped++;
+		atomic_long_inc(&vport->err_stats.rx_dropped);
 		break;
 
 	case VPORT_E_RX_ERROR:
-		vport->err_stats.rx_errors++;
+		atomic_long_inc(&vport->err_stats.rx_errors);
 		break;
 
 	case VPORT_E_TX_DROPPED:
-		vport->err_stats.tx_dropped++;
+		atomic_long_inc(&vport->err_stats.tx_dropped);
 		break;
 
 	case VPORT_E_TX_ERROR:
-		vport->err_stats.tx_errors++;
+		atomic_long_inc(&vport->err_stats.tx_errors);
 		break;
 	}
-
-	spin_unlock(&vport->stats_lock);
 }
 
 static void free_vport_rcu(struct rcu_head *rcu)

datapath/vport.h

@@ -67,13 +67,13 @@ int ovs_vport_get_egress_tun_info(struct vport *vport, struct sk_buff *skb,
 				  struct ovs_tunnel_info *info);
 
 /* The following definitions are for implementers of vport devices: */
-
 struct vport_err_stats {
-	u64 rx_dropped;
-	u64 rx_errors;
-	u64 tx_dropped;
-	u64 tx_errors;
+	atomic_long_t rx_dropped;
+	atomic_long_t rx_errors;
+	atomic_long_t tx_dropped;
+	atomic_long_t tx_errors;
 };
+
 /**
  * struct vport_portids - array of netlink portids of a vport.
  *                        must be protected by rcu.
@@ -100,7 +100,6 @@ struct vport_portids {
  * @dp_hash_node: Element in @datapath->ports hash table in datapath.c.
  * @ops: Class structure.
  * @percpu_stats: Points to per-CPU statistics used and maintained by vport
- * @stats_lock: Protects @err_stats.
  * @err_stats: Points to error statistics used and maintained by vport
  */
 struct vport {
@@ -114,8 +113,6 @@ struct vport {
 	const struct vport_ops *ops;
 
 	struct pcpu_sw_netstats __percpu *percpu_stats;
-
-	spinlock_t stats_lock;
 	struct vport_err_stats err_stats;
 };