net: core: explicitly select a txq before doing l2 forwarding

Currently, the tx queue were selected implicitly in ndo_dfwd_start_xmit(). The
will cause several issues:

- NETIF_F_LLTX were removed for macvlan, so txq lock were done for macvlan
  instead of lower device which misses the necessary txq synchronization for
  lower device such as txq stopping or frozen required by dev watchdog or
  control path.
- dev_hard_start_xmit() was called with NULL txq which bypasses the net device
  watchdog.
- dev_hard_start_xmit() does not check txq everywhere which will lead a crash
  when tso is disabled for lower device.

Fix this by explicitly introducing a new param for .ndo_select_queue() for just
selecting queues in the case of l2 forwarding offload. netdev_pick_tx() was also
extended to accept this parameter and dev_queue_xmit_accel() was used to do l2
forwarding transmission.

With this fixes, NETIF_F_LLTX could be preserved for macvlan and there's no need
to check txq against NULL in dev_hard_start_xmit(). Also there's no need to keep
a dedicated ndo_dfwd_start_xmit() and we can just reuse the code of
dev_queue_xmit() to do the transmission.

In the future, it was also required for macvtap l2 forwarding support since it
provides a necessary synchronization method.

Cc: John Fastabend <john.r.fastabend@intel.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: e1000-devel@lists.sourceforge.net
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -3732,7 +3732,8 @@ static inline int bond_slave_override(struct bonding *bond,
 }
 
 
-static u16 bond_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 bond_select_queue(struct net_device *dev, struct sk_buff *skb,
+			     void *accel_priv)
 {
 	/*
 	 * This helper function exists to help dev_pick_tx get the correct

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

@@ -1833,7 +1833,8 @@ void bnx2x_netif_stop(struct bnx2x *bp, int disable_hw)
 		bnx2x_napi_disable_cnic(bp);
 }
 
-u16 bnx2x_select_queue(struct net_device *dev, struct sk_buff *skb)
+u16 bnx2x_select_queue(struct net_device *dev, struct sk_buff *skb,
+		       void *accel_priv)
 {
 	struct bnx2x *bp = netdev_priv(dev);
 

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.h

@@ -524,7 +524,8 @@ int bnx2x_set_vf_mac(struct net_device *dev, int queue, u8 *mac);
 int bnx2x_set_vf_vlan(struct net_device *netdev, int vf, u16 vlan, u8 qos);
 
 /* select_queue callback */
-u16 bnx2x_select_queue(struct net_device *dev, struct sk_buff *skb);
+u16 bnx2x_select_queue(struct net_device *dev, struct sk_buff *skb,
+		       void *accel_priv);
 
 static inline void bnx2x_update_rx_prod(struct bnx2x *bp,
 					struct bnx2x_fastpath *fp,

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -6827,12 +6827,20 @@ static inline int ixgbe_maybe_stop_tx(struct ixgbe_ring *tx_ring, u16 size)
 	return __ixgbe_maybe_stop_tx(tx_ring, size);
 }
 
-#ifdef IXGBE_FCOE
-static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb,
+			      void *accel_priv)
 {
+	struct ixgbe_fwd_adapter *fwd_adapter = accel_priv;
+#ifdef IXGBE_FCOE
 	struct ixgbe_adapter *adapter;
 	struct ixgbe_ring_feature *f;
 	int txq;
+#endif
+
+	if (fwd_adapter)
+		return skb->queue_mapping + fwd_adapter->tx_base_queue;
+
+#ifdef IXGBE_FCOE
 
 	/*
 	 * only execute the code below if protocol is FCoE
@@ -6858,9 +6866,11 @@ static u16 ixgbe_select_queue(struct net_device *dev, struct sk_buff *skb)
 		txq -= f->indices;
 
 	return txq + f->offset;
+#else
+	return __netdev_pick_tx(dev, skb);
+#endif
 }
 
-#endif
 netdev_tx_t ixgbe_xmit_frame_ring(struct sk_buff *skb,
 			  struct ixgbe_adapter *adapter,
 			  struct ixgbe_ring *tx_ring)
@@ -7629,27 +7639,11 @@ static void ixgbe_fwd_del(struct net_device *pdev, void *priv)
 	kfree(fwd_adapter);
 }
 
-static netdev_tx_t ixgbe_fwd_xmit(struct sk_buff *skb,
-				  struct net_device *dev,
-				  void *priv)
-{
-	struct ixgbe_fwd_adapter *fwd_adapter = priv;
-	unsigned int queue;
-	struct ixgbe_ring *tx_ring;
-
-	queue = skb->queue_mapping + fwd_adapter->tx_base_queue;
-	tx_ring = fwd_adapter->real_adapter->tx_ring[queue];
-
-	return __ixgbe_xmit_frame(skb, dev, tx_ring);
-}
-
 static const struct net_device_ops ixgbe_netdev_ops = {
 	.ndo_open		= ixgbe_open,
 	.ndo_stop		= ixgbe_close,
 	.ndo_start_xmit		= ixgbe_xmit_frame,
-#ifdef IXGBE_FCOE
 	.ndo_select_queue	= ixgbe_select_queue,
-#endif
 	.ndo_set_rx_mode	= ixgbe_set_rx_mode,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_set_mac_address	= ixgbe_set_mac,
@@ -7689,7 +7683,6 @@ static const struct net_device_ops ixgbe_netdev_ops = {
 	.ndo_bridge_getlink	= ixgbe_ndo_bridge_getlink,
 	.ndo_dfwd_add_station	= ixgbe_fwd_add,
 	.ndo_dfwd_del_station	= ixgbe_fwd_del,
-	.ndo_dfwd_start_xmit	= ixgbe_fwd_xmit,
 };
 
 /**

drivers/net/ethernet/lantiq_etop.c

@@ -619,7 +619,8 @@ ltq_etop_set_multicast_list(struct net_device *dev)
 }
 
 static u16
-ltq_etop_select_queue(struct net_device *dev, struct sk_buff *skb)
+ltq_etop_select_queue(struct net_device *dev, struct sk_buff *skb,
+		      void *accel_priv)
 {
 	/* we are currently only using the first queue */
 	return 0;

drivers/net/ethernet/mellanox/mlx4/en_tx.c

@@ -592,7 +592,8 @@ static void build_inline_wqe(struct mlx4_en_tx_desc *tx_desc, struct sk_buff *sk
 	}
 }
 
-u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb)
+u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb,
+			 void *accel_priv)
 {
 	struct mlx4_en_priv *priv = netdev_priv(dev);
 	u16 rings_p_up = priv->num_tx_rings_p_up;

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h

@@ -714,7 +714,8 @@ int mlx4_en_set_cq_moder(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq);
 int mlx4_en_arm_cq(struct mlx4_en_priv *priv, struct mlx4_en_cq *cq);
 
 void mlx4_en_tx_irq(struct mlx4_cq *mcq);
-u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb);
+u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb,
+			 void *accel_priv);
 netdev_tx_t mlx4_en_xmit(struct sk_buff *skb, struct net_device *dev);
 
 int mlx4_en_create_tx_ring(struct mlx4_en_priv *priv,

drivers/net/ethernet/tile/tilegx.c

@@ -2080,7 +2080,8 @@ static int tile_net_tx(struct sk_buff *skb, struct net_device *dev)
 }
 
 /* Return subqueue id on this core (one per core). */
-static u16 tile_net_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 tile_net_select_queue(struct net_device *dev, struct sk_buff *skb,
+				 void *accel_priv)
 {
 	return smp_processor_id();
 }

drivers/net/macvlan.c

@@ -299,7 +299,7 @@ netdev_tx_t macvlan_start_xmit(struct sk_buff *skb,
 
 	if (vlan->fwd_priv) {
 		skb->dev = vlan->lowerdev;
-		ret = dev_hard_start_xmit(skb, skb->dev, NULL, vlan->fwd_priv);
+		ret = dev_queue_xmit_accel(skb, vlan->fwd_priv);
 	} else {
 		ret = macvlan_queue_xmit(skb, dev);
 	}
@@ -365,10 +365,8 @@ static int macvlan_open(struct net_device *dev)
 		 */
 		if (IS_ERR_OR_NULL(vlan->fwd_priv)) {
 			vlan->fwd_priv = NULL;
-		} else {
-			dev->features &= ~NETIF_F_LLTX;
+		} else
 			return 0;
-		}
 	}
 
 	err = -EBUSY;
@@ -702,8 +700,7 @@ static netdev_features_t macvlan_fix_features(struct net_device *dev,
 	features = netdev_increment_features(vlan->lowerdev->features,
 					     features,
 					     mask);
-	if (!vlan->fwd_priv)
-		features |= NETIF_F_LLTX;
+	features |= NETIF_F_LLTX;
 
 	return features;
 }

drivers/net/team/team.c

@@ -1647,7 +1647,8 @@ static netdev_tx_t team_xmit(struct sk_buff *skb, struct net_device *dev)
 	return NETDEV_TX_OK;
 }
 
-static u16 team_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 team_select_queue(struct net_device *dev, struct sk_buff *skb,
+			     void *accel_priv)
 {
 	/*
 	 * This helper function exists to help dev_pick_tx get the correct

drivers/net/tun.c

@@ -348,7 +348,8 @@ static void tun_flow_update(struct tun_struct *tun, u32 rxhash,
  * different rxq no. here. If we could not get rxhash, then we would
  * hope the rxq no. may help here.
  */
-static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb,
+			    void *accel_priv)
 {
 	struct tun_struct *tun = netdev_priv(dev);
 	struct tun_flow_entry *e;

drivers/net/wireless/mwifiex/main.c

@@ -746,7 +746,8 @@ static struct net_device_stats *mwifiex_get_stats(struct net_device *dev)
 }
 
 static u16
-mwifiex_netdev_select_wmm_queue(struct net_device *dev, struct sk_buff *skb)
+mwifiex_netdev_select_wmm_queue(struct net_device *dev, struct sk_buff *skb,
+				void *accel_priv)
 {
 	skb->priority = cfg80211_classify8021d(skb);
 	return mwifiex_1d_to_wmm_queue[skb->priority];

drivers/staging/bcm/Bcmnet.c

@@ -39,7 +39,8 @@ static INT bcm_close(struct net_device *dev)
 	return 0;
 }
 
-static u16 bcm_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 bcm_select_queue(struct net_device *dev, struct sk_buff *skb,
+			    void *accel_priv)
 {
 	return ClassifyPacket(netdev_priv(dev), skb);
 }

drivers/staging/netlogic/xlr_net.c

@@ -306,7 +306,8 @@ static netdev_tx_t xlr_net_start_xmit(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 }
 
-static u16 xlr_net_select_queue(struct net_device *ndev, struct sk_buff *skb)
+static u16 xlr_net_select_queue(struct net_device *ndev, struct sk_buff *skb,
+				void *accel_priv)
 {
 	return (u16)smp_processor_id();
 }

drivers/staging/rtl8188eu/os_dep/os_intfs.c

@@ -652,7 +652,8 @@ static unsigned int rtw_classify8021d(struct sk_buff *skb)
 	return dscp >> 5;
 }
 
-static u16 rtw_select_queue(struct net_device *dev, struct sk_buff *skb)
+static u16 rtw_select_queue(struct net_device *dev, struct sk_buff *skb,
+			    void *accel_priv)
 {
 	struct adapter	*padapter = rtw_netdev_priv(dev);
 	struct mlme_priv *pmlmepriv = &padapter->mlmepriv;

include/linux/netdevice.h

@@ -769,7 +769,8 @@ struct netdev_phys_port_id {
  *        (can also return NETDEV_TX_LOCKED iff NETIF_F_LLTX)
  *	Required can not be NULL.
  *
- * u16 (*ndo_select_queue)(struct net_device *dev, struct sk_buff *skb);
+ * u16 (*ndo_select_queue)(struct net_device *dev, struct sk_buff *skb,
+ *                         void *accel_priv);
  *	Called to decide which queue to when device supports multiple
  *	transmit queues.
  *
@@ -990,7 +991,8 @@ struct net_device_ops {
 	netdev_tx_t		(*ndo_start_xmit) (struct sk_buff *skb,
 						   struct net_device *dev);
 	u16			(*ndo_select_queue)(struct net_device *dev,
-						    struct sk_buff *skb);
+						    struct sk_buff *skb,
+						    void *accel_priv);
 	void			(*ndo_change_rx_flags)(struct net_device *dev,
 						       int flags);
 	void			(*ndo_set_rx_mode)(struct net_device *dev);
@@ -1529,7 +1531,8 @@ static inline void netdev_for_each_tx_queue(struct net_device *dev,
 }
 
 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
-				    struct sk_buff *skb);
+				    struct sk_buff *skb,
+				    void *accel_priv);
 u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb);
 
 /*
@@ -1819,6 +1822,7 @@ int dev_close(struct net_device *dev);
 void dev_disable_lro(struct net_device *dev);
 int dev_loopback_xmit(struct sk_buff *newskb);
 int dev_queue_xmit(struct sk_buff *skb);
+int dev_queue_xmit_accel(struct sk_buff *skb, void *accel_priv);
 int register_netdevice(struct net_device *dev);
 void unregister_netdevice_queue(struct net_device *dev, struct list_head *head);
 void unregister_netdevice_many(struct list_head *head);
@@ -2426,7 +2430,7 @@ int dev_change_carrier(struct net_device *, bool new_carrier);
 int dev_get_phys_port_id(struct net_device *dev,
 			 struct netdev_phys_port_id *ppid);
 int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
-			struct netdev_queue *txq, void *accel_priv);
+			struct netdev_queue *txq);
 int dev_forward_skb(struct net_device *dev, struct sk_buff *skb);
 
 extern int		netdev_budget;

net/core/dev.c

@@ -2539,7 +2539,7 @@ static inline int skb_needs_linearize(struct sk_buff *skb,
 }
 
 int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
-			struct netdev_queue *txq, void *accel_priv)
+			struct netdev_queue *txq)
 {
 	const struct net_device_ops *ops = dev->netdev_ops;
 	int rc = NETDEV_TX_OK;
@@ -2605,13 +2605,10 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 			dev_queue_xmit_nit(skb, dev);
 
 		skb_len = skb->len;
-		if (accel_priv)
-			rc = ops->ndo_dfwd_start_xmit(skb, dev, accel_priv);
-		else
 			rc = ops->ndo_start_xmit(skb, dev);
 
 		trace_net_dev_xmit(skb, rc, dev, skb_len);
-		if (rc == NETDEV_TX_OK && txq)
+		if (rc == NETDEV_TX_OK)
 			txq_trans_update(txq);
 		return rc;
 	}
@@ -2627,10 +2624,7 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 			dev_queue_xmit_nit(nskb, dev);
 
 		skb_len = nskb->len;
-		if (accel_priv)
-			rc = ops->ndo_dfwd_start_xmit(nskb, dev, accel_priv);
-		else
-			rc = ops->ndo_start_xmit(nskb, dev);
+		rc = ops->ndo_start_xmit(nskb, dev);
 		trace_net_dev_xmit(nskb, rc, dev, skb_len);
 		if (unlikely(rc != NETDEV_TX_OK)) {
 			if (rc & ~NETDEV_TX_MASK)
@@ -2811,7 +2805,7 @@ EXPORT_SYMBOL(dev_loopback_xmit);
  *      the BH enable code must have IRQs enabled so that it will not deadlock.
  *          --BLG
  */
-int dev_queue_xmit(struct sk_buff *skb)
+int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
 {
 	struct net_device *dev = skb->dev;
 	struct netdev_queue *txq;
@@ -2827,7 +2821,7 @@ int dev_queue_xmit(struct sk_buff *skb)
 
 	skb_update_prio(skb);
 
-	txq = netdev_pick_tx(dev, skb);
+	txq = netdev_pick_tx(dev, skb, accel_priv);
 	q = rcu_dereference_bh(txq->qdisc);
 
 #ifdef CONFIG_NET_CLS_ACT
@@ -2863,7 +2857,7 @@ int dev_queue_xmit(struct sk_buff *skb)
 
 			if (!netif_xmit_stopped(txq)) {
 				__this_cpu_inc(xmit_recursion);
-				rc = dev_hard_start_xmit(skb, dev, txq, NULL);
+				rc = dev_hard_start_xmit(skb, dev, txq);
 				__this_cpu_dec(xmit_recursion);
 				if (dev_xmit_complete(rc)) {
 					HARD_TX_UNLOCK(dev, txq);
@@ -2892,8 +2886,19 @@ int dev_queue_xmit(struct sk_buff *skb)
 	rcu_read_unlock_bh();
 	return rc;
 }
+
+int dev_queue_xmit(struct sk_buff *skb)
+{
+	return __dev_queue_xmit(skb, NULL);
+}
 EXPORT_SYMBOL(dev_queue_xmit);
 
+int dev_queue_xmit_accel(struct sk_buff *skb, void *accel_priv)
+{
+	return __dev_queue_xmit(skb, accel_priv);
+}
+EXPORT_SYMBOL(dev_queue_xmit_accel);
+
 
 /*=======================================================================
 			Receiver routines

net/core/flow_dissector.c

@@ -395,17 +395,21 @@ u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 EXPORT_SYMBOL(__netdev_pick_tx);
 
 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
-				    struct sk_buff *skb)
+				    struct sk_buff *skb,
+				    void *accel_priv)
 {
 	int queue_index = 0;
 
 	if (dev->real_num_tx_queues != 1) {
 		const struct net_device_ops *ops = dev->netdev_ops;
 		if (ops->ndo_select_queue)
-			queue_index = ops->ndo_select_queue(dev, skb);
+			queue_index = ops->ndo_select_queue(dev, skb,
+							    accel_priv);
 		else
 			queue_index = __netdev_pick_tx(dev, skb);
-		queue_index = dev_cap_txqueue(dev, queue_index);
+
+		if (!accel_priv)
+			queue_index = dev_cap_txqueue(dev, queue_index);
 	}
 
 	skb_set_queue_mapping(skb, queue_index);

net/core/netpoll.c

@@ -375,7 +375,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb,
 	if (skb_queue_len(&npinfo->txq) == 0 && !netpoll_owner_active(dev)) {
 		struct netdev_queue *txq;
 
-		txq = netdev_pick_tx(dev, skb);
+		txq = netdev_pick_tx(dev, skb, NULL);
 
 		/* try until next clock tick */
 		for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;