vlan: lockless transmit path

vlan is a stacked device, like tunnels. We should use the lockless
mechanism we are using in tunnels and loopback.

This patch completely removes locking in TX path.

tx stat counters are added into existing percpu stat structure, renamed
from vlan_rx_stats to vlan_pcpu_stats.

Note : this partially reverts commit 2e59af3dcbdf (vlan: multiqueue vlan
device)

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 35 insertions, 26 deletions

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index f3c9552f6ba..2fa3f4a3f60 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -141,7 +141,7 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
 		  struct packet_type *ptype, struct net_device *orig_dev)
 {
 	struct vlan_hdr *vhdr;
-	struct vlan_rx_stats *rx_stats;
+	struct vlan_pcpu_stats *rx_stats;
 	struct net_device *vlan_dev;
 	u16 vlan_id;
 	u16 vlan_tci;
@@ -177,7 +177,7 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
 	} else {
 		skb->dev = vlan_dev;
 
-		rx_stats = this_cpu_ptr(vlan_dev_info(skb->dev)->vlan_rx_stats);
+		rx_stats = this_cpu_ptr(vlan_dev_info(skb->dev)->vlan_pcpu_stats);
 
 		u64_stats_update_begin(&rx_stats->syncp);
 		rx_stats->rx_packets++;
@@ -310,8 +310,6 @@ static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
 static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
 					    struct net_device *dev)
 {
-	int i = skb_get_queue_mapping(skb);
-	struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
 	struct vlan_ethhdr *veth = (struct vlan_ethhdr *)(skb->data);
 	unsigned int len;
 	int ret;
@@ -334,10 +332,16 @@ static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
 	ret = dev_queue_xmit(skb);
 
 	if (likely(ret == NET_XMIT_SUCCESS || ret == NET_XMIT_CN)) {
-		txq->tx_packets++;
-		txq->tx_bytes += len;
-	} else
-		txq->tx_dropped++;
+		struct vlan_pcpu_stats *stats;
+
+		stats = this_cpu_ptr(vlan_dev_info(dev)->vlan_pcpu_stats);
+		u64_stats_update_begin(&stats->syncp);
+		stats->tx_packets++;
+		stats->tx_bytes += len;
+		u64_stats_update_begin(&stats->syncp);
+	} else {
+		this_cpu_inc(vlan_dev_info(dev)->vlan_pcpu_stats->tx_dropped);
+	}
 
 	return ret;
 }
@@ -696,6 +700,7 @@ static int vlan_dev_init(struct net_device *dev)
 		      (1<<__LINK_STATE_PRESENT);
 
 	dev->features |= real_dev->features & real_dev->vlan_features;
+	dev->features |= NETIF_F_LLTX;
 	dev->gso_max_size = real_dev->gso_max_size;
 
 	/* ipv6 shared card related stuff */
@@ -728,8 +733,8 @@ static int vlan_dev_init(struct net_device *dev)
 
 	vlan_dev_set_lockdep_class(dev, subclass);
 
-	vlan_dev_info(dev)->vlan_rx_stats = alloc_percpu(struct vlan_rx_stats);
-	if (!vlan_dev_info(dev)->vlan_rx_stats)
+	vlan_dev_info(dev)->vlan_pcpu_stats = alloc_percpu(struct vlan_pcpu_stats);
+	if (!vlan_dev_info(dev)->vlan_pcpu_stats)
 		return -ENOMEM;
 
 	return 0;
@@ -741,8 +746,8 @@ static void vlan_dev_uninit(struct net_device *dev)
 	struct vlan_dev_info *vlan = vlan_dev_info(dev);
 	int i;
 
-	free_percpu(vlan->vlan_rx_stats);
-	vlan->vlan_rx_stats = NULL;
+	free_percpu(vlan->vlan_pcpu_stats);
+	vlan->vlan_pcpu_stats = NULL;
 	for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
 		while ((pm = vlan->egress_priority_map[i]) != NULL) {
 			vlan->egress_priority_map[i] = pm->next;
@@ -780,33 +785,37 @@ static u32 vlan_ethtool_get_flags(struct net_device *dev)
 
 static struct rtnl_link_stats64 *vlan_dev_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
 {
-	dev_txq_stats_fold(dev, stats);
 
-	if (vlan_dev_info(dev)->vlan_rx_stats) {
-		struct vlan_rx_stats *p, accum = {0};
+	if (vlan_dev_info(dev)->vlan_pcpu_stats) {
+		struct vlan_pcpu_stats *p;
+		u32 rx_errors = 0, tx_dropped = 0;
 		int i;
 
 		for_each_possible_cpu(i) {
-			u64 rxpackets, rxbytes, rxmulticast;
+			u64 rxpackets, rxbytes, rxmulticast, txpackets, txbytes;
 			unsigned int start;
 
-			p = per_cpu_ptr(vlan_dev_info(dev)->vlan_rx_stats, i);
+			p = per_cpu_ptr(vlan_dev_info(dev)->vlan_pcpu_stats, i);
 			do {
 				start = u64_stats_fetch_begin_bh(&p->syncp);
 				rxpackets	= p->rx_packets;
 				rxbytes		= p->rx_bytes;
 				rxmulticast	= p->rx_multicast;
+				txpackets	= p->tx_packets;
+				txbytes		= p->tx_bytes;
 			} while (u64_stats_fetch_retry_bh(&p->syncp, start));
-			accum.rx_packets += rxpackets;
-			accum.rx_bytes   += rxbytes;
-			accum.rx_multicast += rxmulticast;
-			/* rx_errors is ulong, not protected by syncp */
-			accum.rx_errors  += p->rx_errors;
+
+			stats->rx_packets	+= rxpackets;
+			stats->rx_bytes		+= rxbytes;
+			stats->multicast	+= rxmulticast;
+			stats->tx_packets	+= txpackets;
+			stats->tx_bytes		+= txbytes;
+			/* rx_errors & tx_dropped are u32 */
+			rx_errors	+= p->rx_errors;
+			tx_dropped	+= p->tx_dropped;
 		}
-		stats->rx_packets = accum.rx_packets;
-		stats->rx_bytes   = accum.rx_bytes;
-		stats->rx_errors  = accum.rx_errors;
-		stats->multicast  = accum.rx_multicast;
+		stats->rx_errors  = rx_errors;
+		stats->tx_dropped = tx_dropped;
 	}
 	return stats;
 }