netpoll: Remove dead packet receive code (CONFIG_NETPOLL_TRAP)

The netpoll packet receive code only becomes active if the netpoll
rx_skb_hook is implemented, and there is not a single implementation
of the netpoll rx_skb_hook in the kernel.

All of the out of tree implementations I have found all call
netpoll_poll which was removed from the kernel in 2011, so this
change should not add any additional breakage.

There are problems with the netpoll packet receive code.  __netpoll_rx
does not call dev_kfree_skb_irq or dev_kfree_skb_any in hard irq
context.  netpoll_neigh_reply leaks every skb it receives.  Reception
of packets does not work successfully on stacked devices (aka bonding,
team, bridge, and vlans).

Given that the netpoll packet receive code is buggy, there are no
out of tree users that will be merged soon, and the code has
not been used for in tree for a decade let's just remove it.

Reverting this commit can server as a starting point for anyone
who wants to resurrect netpoll packet reception support.

Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 17 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index b8d8c80..4b6d12c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1979,9 +1979,6 @@ struct net_device *__dev_get_by_index(struct net *net, int ifindex);
 struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
 int netdev_get_name(struct net *net, char *name, int ifindex);
 int dev_restart(struct net_device *dev);
-#ifdef CONFIG_NETPOLL_TRAP
-int netpoll_trap(void);
-#endif
 int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb);
 
 static inline unsigned int skb_gro_offset(const struct sk_buff *skb)
@@ -2186,12 +2183,6 @@ static inline void netif_tx_start_all_queues(struct net_device *dev)
 
 static inline void netif_tx_wake_queue(struct netdev_queue *dev_queue)
 {
-#ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap()) {
-		netif_tx_start_queue(dev_queue);
-		return;
-	}
-#endif
 	if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state))
 		__netif_schedule(dev_queue->qdisc);
 }
@@ -2435,10 +2426,6 @@ static inline void netif_start_subqueue(struct net_device *dev, u16 queue_index)
 static inline void netif_stop_subqueue(struct net_device *dev, u16 queue_index)
 {
 	struct netdev_queue *txq = netdev_get_tx_queue(dev, queue_index);
-#ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap())
-		return;
-#endif
 	netif_tx_stop_queue(txq);
 }
 
@@ -2473,10 +2460,6 @@ static inline bool netif_subqueue_stopped(const struct net_device *dev,
 static inline void netif_wake_subqueue(struct net_device *dev, u16 queue_index)
 {
 	struct netdev_queue *txq = netdev_get_tx_queue(dev, queue_index);
-#ifdef CONFIG_NETPOLL_TRAP
-	if (netpoll_trap())
-		return;
-#endif
 	if (test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &txq->state))
 		__netif_schedule(txq->qdisc);
 }