net: remove dev_txq_stats_fold()

After recent changes, (percpu stats on vlan/tunnels...), we dont need
anymore per struct netdev_queue tx_bytes/tx_packets/tx_dropped counters.

Only remaining users are ixgbe, sch_teql, gianfar & macvlan :

1) ixgbe can be converted to use existing tx_ring counters.

2) macvlan incremented txq->tx_dropped, it can use the
dev->stats.tx_dropped counter.

3) sch_teql : almost revert ab35cd4b8f (Use net_device internal stats)
    Now we have ndo_get_stats64(), use it, even for "unsigned long"
fields (No need to bring back a struct net_device_stats)

4) gianfar adds a stats structure per tx queue to hold
tx_bytes/tx_packets

This removes a lockdep warning (and possible lockup) in rndis gadget,
calling dev_get_stats() from hard IRQ context.

Ref: http://www.spinics.net/lists/netdev/msg149202.html

Reported-by: Neil Jones <neiljay@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Jarek Poplawski <jarkao2@gmail.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
CC: Sandeep Gopalpet <sandeep.kumar@freescale.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/gianfar.c

@@ -433,7 +433,6 @@ static void gfar_init_mac(struct net_device *ndev)
 static struct net_device_stats *gfar_get_stats(struct net_device *dev)
 {
 	struct gfar_private *priv = netdev_priv(dev);
-	struct netdev_queue *txq;
 	unsigned long rx_packets = 0, rx_bytes = 0, rx_dropped = 0;
 	unsigned long tx_packets = 0, tx_bytes = 0;
 	int i = 0;
@@ -449,9 +448,8 @@ static struct net_device_stats *gfar_get_stats(struct net_device *dev)
 	dev->stats.rx_dropped = rx_dropped;
 
 	for (i = 0; i < priv->num_tx_queues; i++) {
-		txq = netdev_get_tx_queue(dev, i);
+		tx_bytes += priv->tx_queue[i]->stats.tx_bytes;
-		tx_bytes += txq->tx_bytes;
+		tx_packets += priv->tx_queue[i]->stats.tx_packets;
-		tx_packets += txq->tx_packets;
 	}
 
 	dev->stats.tx_bytes = tx_bytes;
@@ -2108,8 +2106,8 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	}
 
 	/* Update transmit stats */
-	txq->tx_bytes += skb->len;
+	tx_queue->stats.tx_bytes += skb->len;
-	txq->tx_packets ++;
+	tx_queue->stats.tx_packets++;
 
 	txbdp = txbdp_start = tx_queue->cur_tx;
 	lstatus = txbdp->lstatus;

drivers/net/gianfar.h

@@ -907,12 +907,21 @@ enum {
 	MQ_MG_MODE
 };
 
+/*
+ * Per TX queue stats
+ */
+struct tx_q_stats {
+	unsigned long tx_packets;
+	unsigned long tx_bytes;
+};
+
 /**
  *	struct gfar_priv_tx_q - per tx queue structure
  *	@txlock: per queue tx spin lock
  *	@tx_skbuff:skb pointers
  *	@skb_curtx: to be used skb pointer
  *	@skb_dirtytx:the last used skb pointer
+ *	@stats: bytes/packets stats
  *	@qindex: index of this queue
  *	@dev: back pointer to the dev structure
  *	@grp: back pointer to the group to which this queue belongs
@@ -934,6 +943,7 @@ struct gfar_priv_tx_q {
 	struct	txbd8 *tx_bd_base;
 	struct	txbd8 *cur_tx;
 	struct	txbd8 *dirty_tx;
+	struct tx_q_stats stats;
 	struct	net_device *dev;
 	struct gfar_priv_grp *grp;
 	u16	skb_curtx;

drivers/net/ixgbe/ixgbe_main.c

@@ -6667,8 +6667,6 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
 			  struct ixgbe_adapter *adapter,
 			  struct ixgbe_ring *tx_ring)
 {
-	struct net_device *netdev = tx_ring->netdev;
-	struct netdev_queue *txq;
 	unsigned int first;
 	unsigned int tx_flags = 0;
 	u8 hdr_len = 0;
@@ -6765,9 +6763,6 @@ netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
 		/* add the ATR filter if ATR is on */
 		if (test_bit(__IXGBE_TX_FDIR_INIT_DONE, &tx_ring->state))
 			ixgbe_atr(tx_ring, skb, tx_flags, protocol);
-		txq = netdev_get_tx_queue(netdev, tx_ring->queue_index);
-		txq->tx_bytes += skb->len;
-		txq->tx_packets++;
 		ixgbe_tx_queue(tx_ring, tx_flags, count, skb->len, hdr_len);
 		ixgbe_maybe_stop_tx(tx_ring, DESC_NEEDED);
 
@@ -6925,8 +6920,6 @@ static struct rtnl_link_stats64 *ixgbe_get_stats64(struct net_device *netdev,
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
 	int i;
 
-	/* accurate rx/tx bytes/packets stats */
-	dev_txq_stats_fold(netdev, stats);
 	rcu_read_lock();
 	for (i = 0; i < adapter->num_rx_queues; i++) {
 		struct ixgbe_ring *ring = ACCESS_ONCE(adapter->rx_ring[i]);
@@ -6943,6 +6936,22 @@ static struct rtnl_link_stats64 *ixgbe_get_stats64(struct net_device *netdev,
 			stats->rx_bytes   += bytes;
 		}
 	}
+
+	for (i = 0; i < adapter->num_tx_queues; i++) {
+		struct ixgbe_ring *ring = ACCESS_ONCE(adapter->tx_ring[i]);
+		u64 bytes, packets;
+		unsigned int start;
+
+		if (ring) {
+			do {
+				start = u64_stats_fetch_begin_bh(&ring->syncp);
+				packets = ring->stats.packets;
+				bytes   = ring->stats.bytes;
+			} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
+			stats->tx_packets += packets;
+			stats->tx_bytes   += bytes;
+		}
+	}
 	rcu_read_unlock();
 	/* following stats updated by ixgbe_watchdog_task() */
 	stats->multicast	= netdev->stats.multicast;

drivers/net/macvtap.c

@@ -585,7 +585,7 @@ err:
 	rcu_read_lock_bh();
 	vlan = rcu_dereference(q->vlan);
 	if (vlan)
-		netdev_get_tx_queue(vlan->dev, 0)->tx_dropped++;
+		vlan->dev->stats.tx_dropped++;
 	rcu_read_unlock_bh();
 
 	return err;

include/linux/netdevice.h

@@ -520,9 +520,6 @@ struct netdev_queue {
 	 * please use this field instead of dev->trans_start
 	 */
 	unsigned long		trans_start;
-	u64			tx_bytes;
-	u64			tx_packets;
-	u64			tx_dropped;
 } ____cacheline_aligned_in_smp;
 
 static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
@@ -2265,8 +2262,6 @@ extern void		dev_load(struct net *net, const char *name);
 extern void		dev_mcast_init(void);
 extern struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
 					       struct rtnl_link_stats64 *storage);
-extern void		dev_txq_stats_fold(const struct net_device *dev,
-					   struct rtnl_link_stats64 *stats);
 
 extern int		netdev_max_backlog;
 extern int		netdev_tstamp_prequeue;

net/core/dev.c

@@ -5523,34 +5523,6 @@ void netdev_run_todo(void)
 	}
 }
 
-/**
- *	dev_txq_stats_fold - fold tx_queues stats
- *	@dev: device to get statistics from
- *	@stats: struct rtnl_link_stats64 to hold results
- */
-void dev_txq_stats_fold(const struct net_device *dev,
-			struct rtnl_link_stats64 *stats)
-{
-	u64 tx_bytes = 0, tx_packets = 0, tx_dropped = 0;
-	unsigned int i;
-	struct netdev_queue *txq;
-
-	for (i = 0; i < dev->num_tx_queues; i++) {
-		txq = netdev_get_tx_queue(dev, i);
-		spin_lock_bh(&txq->_xmit_lock);
-		tx_bytes   += txq->tx_bytes;
-		tx_packets += txq->tx_packets;
-		tx_dropped += txq->tx_dropped;
-		spin_unlock_bh(&txq->_xmit_lock);
-	}
-	if (tx_bytes || tx_packets || tx_dropped) {
-		stats->tx_bytes   = tx_bytes;
-		stats->tx_packets = tx_packets;
-		stats->tx_dropped = tx_dropped;
-	}
-}
-EXPORT_SYMBOL(dev_txq_stats_fold);
-
 /* Convert net_device_stats to rtnl_link_stats64.  They have the same
  * fields in the same order, with only the type differing.
  */
@@ -5594,7 +5566,6 @@ struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
 		netdev_stats_to_stats64(storage, ops->ndo_get_stats(dev));
 	} else {
 		netdev_stats_to_stats64(storage, &dev->stats);
-		dev_txq_stats_fold(dev, storage);
 	}
 	storage->rx_dropped += atomic_long_read(&dev->rx_dropped);
 	return storage;

net/sched/sch_teql.c

@@ -59,6 +59,10 @@ struct teql_master
 	struct net_device *dev;
 	struct Qdisc *slaves;
 	struct list_head master_list;
+	unsigned long	tx_bytes;
+	unsigned long	tx_packets;
+	unsigned long	tx_errors;
+	unsigned long	tx_dropped;
 };
 
 struct teql_sched_data
@@ -274,7 +278,6 @@ static inline int teql_resolve(struct sk_buff *skb,
 static netdev_tx_t teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct teql_master *master = netdev_priv(dev);
-	struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 	struct Qdisc *start, *q;
 	int busy;
 	int nores;
@@ -314,8 +317,8 @@ restart:
 					__netif_tx_unlock(slave_txq);
 					master->slaves = NEXT_SLAVE(q);
 					netif_wake_queue(dev);
-					txq->tx_packets++;
+					master->tx_packets++;
-					txq->tx_bytes += length;
+					master->tx_bytes += length;
 					return NETDEV_TX_OK;
 				}
 				__netif_tx_unlock(slave_txq);
@@ -342,10 +345,10 @@ restart:
 		netif_stop_queue(dev);
 		return NETDEV_TX_BUSY;
 	}
-	dev->stats.tx_errors++;
+	master->tx_errors++;
 
 drop:
-	txq->tx_dropped++;
+	master->tx_dropped++;
 	dev_kfree_skb(skb);
 	return NETDEV_TX_OK;
 }
@@ -398,6 +401,18 @@ static int teql_master_close(struct net_device *dev)
 	return 0;
 }
 
+static struct rtnl_link_stats64 *teql_master_stats64(struct net_device *dev,
+						     struct rtnl_link_stats64 *stats)
+{
+	struct teql_master *m = netdev_priv(dev);
+
+	stats->tx_packets	= m->tx_packets;
+	stats->tx_bytes		= m->tx_bytes;
+	stats->tx_errors	= m->tx_errors;
+	stats->tx_dropped	= m->tx_dropped;
+	return stats;
+}
+
 static int teql_master_mtu(struct net_device *dev, int new_mtu)
 {
 	struct teql_master *m = netdev_priv(dev);
@@ -422,6 +437,7 @@ static const struct net_device_ops teql_netdev_ops = {
 	.ndo_open	= teql_master_open,
 	.ndo_stop	= teql_master_close,
 	.ndo_start_xmit	= teql_master_xmit,
+	.ndo_get_stats64 = teql_master_stats64,
 	.ndo_change_mtu	= teql_master_mtu,
 };