Merge branch 'bonding-report-transmit-status-to-callers'

Eric Dumazet says:

====================
bonding: report transmit status to callers

First patches cleanup netpoll, and make sure it provides tx status to its users.

Last patch changes bonding to not pretend packets were sent without error.

By providing more accurate status, TCP stack can avoid adding more
packets if the slave qdisc is already full.

This came while testing latest horizon feature in sch_fq, with
very low pacing rate flows, but should benefit hosts under stress.
====================

Signed-off-by: David S. Miller <[e-mail]>

drivers/net/bonding/bond_alb.c

···
 					tx_slave->dev->dev_addr);
 		}
 
-		bond_dev_queue_xmit(bond, skb, tx_slave->dev);
-		goto out;
+		return bond_dev_queue_xmit(bond, skb, tx_slave->dev);
 	}
 
 	if (tx_slave && bond->params.tlb_dynamic_lb) {
···
 	}
 
 	/* no suitable interface, frame not sent */
-	bond_tx_drop(bond->dev, skb);
-out:
-	return NETDEV_TX_OK;
+	return bond_tx_drop(bond->dev, skb);
 }
 
 netdev_tx_t bond_tlb_xmit(struct sk_buff *skb, struct net_device *bond_dev)

drivers/net/bonding/bond_main.c

···
  * @skb: hw accel VLAN tagged skb to transmit
  * @slave_dev: slave that is supposed to xmit this skbuff
  */
-void bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb,
+netdev_tx_t bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb,
 			struct net_device *slave_dev)
 {
 	skb->dev = slave_dev;
···
 	skb_set_queue_mapping(skb, qdisc_skb_cb(skb)->slave_dev_queue_mapping);
 
 	if (unlikely(netpoll_tx_running(bond->dev)))
-		bond_netpoll_send_skb(bond_get_slave_by_dev(bond, slave_dev), skb);
-	else
-		dev_queue_xmit(skb);
+		return bond_netpoll_send_skb(bond_get_slave_by_dev(bond, slave_dev), skb);
+
+	return dev_queue_xmit(skb);
 }
 
 /* In the following 2 functions, bond_vlan_rx_add_vid and bond_vlan_rx_kill_vid,
···
  * it fails, it tries to find the first available slave for transmission.
  * The skb is consumed in all cases, thus the function is void.
  */
-static void bond_xmit_slave_id(struct bonding *bond, struct sk_buff *skb, int slave_id)
+static netdev_tx_t bond_xmit_slave_id(struct bonding *bond, struct sk_buff *skb, int slave_id)
 {
 	struct list_head *iter;
 	struct slave *slave;
···
 	/* Here we start from the slave with slave_id */
 	bond_for_each_slave_rcu(bond, slave, iter) {
 		if (--i < 0) {
-			if (bond_slave_can_tx(slave)) {
-				bond_dev_queue_xmit(bond, skb, slave->dev);
-				return;
-			}
+			if (bond_slave_can_tx(slave))
+				return bond_dev_queue_xmit(bond, skb, slave->dev);
 		}
 	}
 
···
 	bond_for_each_slave_rcu(bond, slave, iter) {
 		if (--i < 0)
 			break;
-		if (bond_slave_can_tx(slave)) {
-			bond_dev_queue_xmit(bond, skb, slave->dev);
-			return;
-		}
+		if (bond_slave_can_tx(slave))
+			return bond_dev_queue_xmit(bond, skb, slave->dev);
 	}
 	/* no slave that can tx has been found */
-	bond_tx_drop(bond->dev, skb);
+	return bond_tx_drop(bond->dev, skb);
 }
 
 /**
···
 		if (iph->protocol == IPPROTO_IGMP) {
 			slave = rcu_dereference(bond->curr_active_slave);
 			if (slave)
-				bond_dev_queue_xmit(bond, skb, slave->dev);
-			else
-				bond_xmit_slave_id(bond, skb, 0);
-			return NETDEV_TX_OK;
+				return bond_dev_queue_xmit(bond, skb, slave->dev);
+			return bond_xmit_slave_id(bond, skb, 0);
 		}
 	}
 
···
 	slave_cnt = READ_ONCE(bond->slave_cnt);
 	if (likely(slave_cnt)) {
 		slave_id = bond_rr_gen_slave_id(bond);
-		bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
-	} else {
-		bond_tx_drop(bond_dev, skb);
+		return bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
 	}
-	return NETDEV_TX_OK;
+	return bond_tx_drop(bond_dev, skb);
 }
 
 /* In active-backup mode, we know that bond->curr_active_slave is always valid if
···
 
 	slave = rcu_dereference(bond->curr_active_slave);
 	if (slave)
-		bond_dev_queue_xmit(bond, skb, slave->dev);
-	else
-		bond_tx_drop(bond_dev, skb);
+		return bond_dev_queue_xmit(bond, skb, slave->dev);
 
-	return NETDEV_TX_OK;
+	return bond_tx_drop(bond_dev, skb);
 }
 
 /* Use this to update slave_array when (a) it's not appropriate to update
···
 	count = slaves ? READ_ONCE(slaves->count) : 0;
 	if (likely(count)) {
 		slave = slaves->arr[bond_xmit_hash(bond, skb) % count];
-		bond_dev_queue_xmit(bond, skb, slave->dev);
-	} else {
-		bond_tx_drop(dev, skb);
+		return bond_dev_queue_xmit(bond, skb, slave->dev);
 	}
-
-	return NETDEV_TX_OK;
+	return bond_tx_drop(dev, skb);
 }
 
 /* in broadcast mode, we send everything to all usable interfaces. */
···
 		}
 	}
 	if (slave && bond_slave_is_up(slave) && slave->link == BOND_LINK_UP)
-		bond_dev_queue_xmit(bond, skb, slave->dev);
-	else
-		bond_tx_drop(bond_dev, skb);
+		return bond_dev_queue_xmit(bond, skb, slave->dev);
 
-	return NETDEV_TX_OK;
+	return bond_tx_drop(bond_dev, skb);
 }
 
 /*------------------------- Device initialization ---------------------------*/
···
 		/* Should never happen, mode already checked */
 		netdev_err(dev, "Unknown bonding mode %d\n", BOND_MODE(bond));
 		WARN_ON_ONCE(1);
-		bond_tx_drop(dev, skb);
-		return NETDEV_TX_OK;
+		return bond_tx_drop(dev, skb);
 	}
 }
 
···
 	if (bond_has_slaves(bond))
 		ret = __bond_start_xmit(skb, dev);
 	else
-		bond_tx_drop(dev, skb);
+		ret = bond_tx_drop(dev, skb);
 	rcu_read_unlock();
 
 	return ret;

drivers/net/macvlan.c

···
 static inline netdev_tx_t macvlan_netpoll_send_skb(struct macvlan_dev *vlan, struct sk_buff *skb)
 {
 #ifdef CONFIG_NET_POLL_CONTROLLER
-	if (vlan->netpoll)
-		netpoll_send_skb(vlan->netpoll, skb);
+	return netpoll_send_skb(vlan->netpoll, skb);
 #else
 	BUG();
-#endif
 	return NETDEV_TX_OK;
+#endif
 }
 
 static netdev_tx_t macvlan_start_xmit(struct sk_buff *skb,

include/linux/if_team.h

···
 static inline void team_netpoll_send_skb(struct team_port *port,
 					 struct sk_buff *skb)
 {
-	struct netpoll *np = port->np;
-
-	if (np)
-		netpoll_send_skb(np, skb);
+	netpoll_send_skb(port->np, skb);
 }
 #else
 static inline void team_netpoll_send_skb(struct team_port *port,

include/linux/netpoll.h

···
 void __netpoll_cleanup(struct netpoll *np);
 void __netpoll_free(struct netpoll *np);
 void netpoll_cleanup(struct netpoll *np);
-void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
-			     struct net_device *dev);
-static inline void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
-{
-	unsigned long flags;
-	local_irq_save(flags);
-	netpoll_send_skb_on_dev(np, skb, np->dev);
-	local_irq_restore(flags);
-}
+netdev_tx_t netpoll_send_skb(struct netpoll *np, struct sk_buff *skb);
 
 #ifdef CONFIG_NETPOLL
 static inline void *netpoll_poll_lock(struct napi_struct *napi)

include/net/bonding.h

···
 }
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
-static inline void bond_netpoll_send_skb(const struct slave *slave,
+static inline netdev_tx_t bond_netpoll_send_skb(const struct slave *slave,
 					 struct sk_buff *skb)
 {
-	struct netpoll *np = slave->np;
-
-	if (np)
-		netpoll_send_skb(np, skb);
+	return netpoll_send_skb(slave->np, skb);
 }
 #else
-static inline void bond_netpoll_send_skb(const struct slave *slave,
+static inline netdev_tx_t bond_netpoll_send_skb(const struct slave *slave,
 					 struct sk_buff *skb)
 {
+	BUG();
+	return NETDEV_TX_OK;
 }
 #endif
 
···
 };
 
 int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond, struct slave *slave);
-void bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb, struct net_device *slave_dev);
+netdev_tx_t bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb, struct net_device *slave_dev);
 int bond_create(struct net *net, const char *name);
 int bond_create_sysfs(struct bond_net *net);
 void bond_destroy_sysfs(struct bond_net *net);
···
 /* exported from bond_netlink.c */
 extern struct rtnl_link_ops bond_link_ops;
 
-static inline void bond_tx_drop(struct net_device *dev, struct sk_buff *skb)
+static inline netdev_tx_t bond_tx_drop(struct net_device *dev, struct sk_buff *skb)
 {
 	atomic_long_inc(&dev->tx_dropped);
 	dev_kfree_skb_any(skb);
+	return NET_XMIT_DROP;
 }
 
 #endif /* _NET_BONDING_H */

net/8021q/vlan_dev.c

···
 static inline netdev_tx_t vlan_netpoll_send_skb(struct vlan_dev_priv *vlan, struct sk_buff *skb)
 {
 #ifdef CONFIG_NET_POLL_CONTROLLER
-	if (vlan->netpoll)
-		netpoll_send_skb(vlan->netpoll, skb);
+	return netpoll_send_skb(vlan->netpoll, skb);
 #else
 	BUG();
-#endif
 	return NETDEV_TX_OK;
+#endif
 }
 
 static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,

net/bridge/br_private.h

···
 static inline void br_netpoll_send_skb(const struct net_bridge_port *p,
 				       struct sk_buff *skb)
 {
-	struct netpoll *np = p->np;
-
-	if (np)
-		netpoll_send_skb(np, skb);
+	netpoll_send_skb(p->np, skb);
 }
 
 int br_netpoll_enable(struct net_bridge_port *p);

net/core/netpoll.c

···
 }
 
 /* call with IRQ disabled */
-void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
-			     struct net_device *dev)
+static netdev_tx_t __netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 {
 	netdev_tx_t status = NETDEV_TX_BUSY;
+	struct net_device *dev;
 	unsigned long tries;
 	/* It is up to the caller to keep npinfo alive. */
 	struct netpoll_info *npinfo;
 
 	lockdep_assert_irqs_disabled();
 
-	npinfo = rcu_dereference_bh(np->dev->npinfo);
+	dev = np->dev;
+	npinfo = rcu_dereference_bh(dev->npinfo);
+
 	if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
 		dev_kfree_skb_irq(skb);
-		return;
+		return NET_XMIT_DROP;
 	}
 
 	/* don't get messages out of order, and no recursion */
···
 		skb_queue_tail(&npinfo->txq, skb);
 		schedule_delayed_work(&npinfo->tx_work,0);
 	}
+	return NETDEV_TX_OK;
 }
-EXPORT_SYMBOL(netpoll_send_skb_on_dev);
+
+netdev_tx_t netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
+{
+	unsigned long flags;
+	netdev_tx_t ret;
+
+	if (unlikely(!np)) {
+		dev_kfree_skb_irq(skb);
+		ret = NET_XMIT_DROP;
+	} else {
+		local_irq_save(flags);
+		ret = __netpoll_send_skb(np, skb);
+		local_irq_restore(flags);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(netpoll_send_skb);
 
 void netpoll_send_udp(struct netpoll *np, const char *msg, int len)
 {

net/dsa/slave.c

···
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	struct dsa_slave_priv *p = netdev_priv(dev);
 
-	if (p->netpoll)
-		netpoll_send_skb(p->netpoll, skb);
+	return netpoll_send_skb(p->netpoll, skb);
 #else
 	BUG();
-#endif
 	return NETDEV_TX_OK;
+#endif
 }
 
 static void dsa_skb_tx_timestamp(struct dsa_slave_priv *p,