Commit b71b5837 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

packet: rework packet_pick_tx_queue() to use common code selection 



Currently packet_pick_tx_queue() is the only caller of
ndo_select_queue() using a fallback argument other than
netdev_pick_tx.

Leveraging rx queue, we can obtain a similar queue selection
behavior using core helpers. After this change, ndo_select_queue()
is always invoked with netdev_pick_tx() as fallback.
We can change ndo_select_queue() signature in a followup patch,
dropping an indirect call per transmitted packet in some scenarios
(e.g. TCP syn and XDP generic xmit)

This changes slightly how af packet queue selection happens when
PACKET_QDISC_BYPASS is set. It's now more similar to plan dev_queue_xmit()
tacking in account both XPS and TC mapping.

 v1  -> v2:
  - rebased after helper name change
 RFC -> v1:
  - initialize sender_cpu to the expected value

Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4bd97d51

include/linux/netdevice.h

+2 −0
Original line number Diff line number Diff line
@@ -2152,6 +2152,8 @@ static inline void netdev_for_each_tx_queue(struct net_device *dev, 
				  &qdisc_xmit_lock_key);	\

}



u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,

		     struct net_device *sb_dev);

struct netdev_queue *netdev_core_pick_tx(struct net_device *dev,

					 struct sk_buff *skb,

					 struct net_device *sb_dev);

net/core/dev.c

+3 −2
Original line number Diff line number Diff line
@@ -3704,7 +3704,7 @@ u16 dev_pick_tx_cpu_id(struct net_device *dev, struct sk_buff *skb, 
}

EXPORT_SYMBOL(dev_pick_tx_cpu_id);



static u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,

u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb,

		     struct net_device *sb_dev)

{

	struct sock *sk = skb->sk;
@@ -3729,6 +3729,7 @@ static u16 netdev_pick_tx(struct net_device *dev, struct sk_buff *skb, 


	return queue_index;

}

EXPORT_SYMBOL(netdev_pick_tx);



struct netdev_queue *netdev_core_pick_tx(struct net_device *dev,

					 struct sk_buff *skb,

net/packet/af_packet.c

+7 −8
Original line number Diff line number Diff line
@@ -275,24 +275,23 @@ static bool packet_use_direct_xmit(const struct packet_sock *po) 
	return po->xmit == packet_direct_xmit;

}



static u16 __packet_pick_tx_queue(struct net_device *dev, struct sk_buff *skb,

				  struct net_device *sb_dev)

{

	return dev_pick_tx_cpu_id(dev, skb, sb_dev, NULL);

}



static u16 packet_pick_tx_queue(struct sk_buff *skb)

{

	struct net_device *dev = skb->dev;

	const struct net_device_ops *ops = dev->netdev_ops;

	int cpu = raw_smp_processor_id();

	u16 queue_index;



#ifdef CONFIG_XPS

	skb->sender_cpu = cpu + 1;

#endif

	skb_record_rx_queue(skb, cpu % dev->real_num_tx_queues);

	if (ops->ndo_select_queue) {

		queue_index = ops->ndo_select_queue(dev, skb, NULL,

						    __packet_pick_tx_queue);

						    netdev_pick_tx);

		queue_index = netdev_cap_txqueue(dev, queue_index);

	} else {

		queue_index = __packet_pick_tx_queue(dev, skb, NULL);

		queue_index = netdev_pick_tx(dev, skb, NULL);

	}



	return queue_index;

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