Commit eae792b7 authored by David S. Miller's avatar David S. Miller

netdev: Add netdev->select_queue() method.

Devices or device layers can set this to control the queue selection
performed by dev_pick_tx().

This function runs under RCU protection, which allows overriding
functions to have some way of synchronizing with things like dynamic
->real_num_tx_queues adjustments.

This makes the spinlock prefetch in dev_queue_xmit() a little bit
less effective, but that's the price right now for correctness.
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e3c50d5d
...@@ -724,6 +724,9 @@ struct net_device ...@@ -724,6 +724,9 @@ struct net_device
void (*poll_controller)(struct net_device *dev); void (*poll_controller)(struct net_device *dev);
#endif #endif
u16 (*select_queue)(struct net_device *dev,
struct sk_buff *skb);
#ifdef CONFIG_NET_NS #ifdef CONFIG_NET_NS
/* Network namespace this network device is inside */ /* Network namespace this network device is inside */
struct net *nd_net; struct net *nd_net;
......
...@@ -1670,6 +1670,9 @@ static struct netdev_queue *dev_pick_tx(struct net_device *dev, ...@@ -1670,6 +1670,9 @@ static struct netdev_queue *dev_pick_tx(struct net_device *dev,
{ {
u16 queue_index = 0; u16 queue_index = 0;
if (dev->select_queue)
queue_index = dev->select_queue(dev, skb);
skb_set_queue_mapping(skb, queue_index); skb_set_queue_mapping(skb, queue_index);
return netdev_get_tx_queue(dev, queue_index); return netdev_get_tx_queue(dev, queue_index);
} }
...@@ -1710,14 +1713,14 @@ int dev_queue_xmit(struct sk_buff *skb) ...@@ -1710,14 +1713,14 @@ int dev_queue_xmit(struct sk_buff *skb)
} }
gso: gso:
txq = dev_pick_tx(dev, skb);
spin_lock_prefetch(&txq->lock);
/* Disable soft irqs for various locks below. Also /* Disable soft irqs for various locks below. Also
* stops preemption for RCU. * stops preemption for RCU.
*/ */
rcu_read_lock_bh(); rcu_read_lock_bh();
txq = dev_pick_tx(dev, skb);
spin_lock_prefetch(&txq->lock);
/* Updates of qdisc are serialized by queue->lock. /* Updates of qdisc are serialized by queue->lock.
* The struct Qdisc which is pointed to by qdisc is now a * The struct Qdisc which is pointed to by qdisc is now a
* rcu structure - it may be accessed without acquiring * rcu structure - it may be accessed without acquiring
......
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