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, 84 deletions

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index a0632af88d8..1b475a5a723 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -31,12 +31,6 @@ struct netpoll {
 	u8 remote_mac[ETH_ALEN];
 
 	struct work_struct cleanup_work;
-
-#ifdef CONFIG_NETPOLL_TRAP
-	void (*rx_skb_hook)(struct netpoll *np, int source, struct sk_buff *skb,
-			    int offset, int len);
-	struct list_head rx; /* rx_np list element */
-#endif
 };
 
 struct netpoll_info {
@@ -50,12 +44,6 @@ struct netpoll_info {
 
 	struct netpoll *netpoll;
 	struct rcu_head rcu;
-
-#ifdef CONFIG_NETPOLL_TRAP
-	spinlock_t rx_lock;
-	struct list_head rx_np; /* netpolls that registered an rx_skb_hook */
-	struct sk_buff_head neigh_tx; /* list of neigh requests to reply to */
-#endif
 };
 
 #ifdef CONFIG_NETPOLL
@@ -84,78 +72,6 @@ static inline void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
 	local_irq_restore(flags);
 }
 
-#ifdef CONFIG_NETPOLL_TRAP
-int netpoll_trap(void);
-void netpoll_set_trap(int trap);
-int __netpoll_rx(struct sk_buff *skb, struct netpoll_info *npinfo);
-static inline bool netpoll_rx_processing(struct netpoll_info *npinfo)
-{
-	return !list_empty(&npinfo->rx_np);
-}
-
-static inline bool netpoll_rx_on(struct sk_buff *skb)
-{
-	struct netpoll_info *npinfo = rcu_dereference_bh(skb->dev->npinfo);
-
-	return npinfo && netpoll_rx_processing(npinfo);
-}
-
-static inline bool netpoll_rx(struct sk_buff *skb)
-{
-	struct netpoll_info *npinfo;
-	unsigned long flags;
-	bool ret = false;
-
-	local_irq_save(flags);
-
-	if (!netpoll_rx_on(skb))
-		goto out;
-
-	npinfo = rcu_dereference_bh(skb->dev->npinfo);
-	spin_lock(&npinfo->rx_lock);
-	/* check rx_processing again with the lock held */
-	if (netpoll_rx_processing(npinfo) && __netpoll_rx(skb, npinfo))
-		ret = true;
-	spin_unlock(&npinfo->rx_lock);
-
-out:
-	local_irq_restore(flags);
-	return ret;
-}
-
-static inline int netpoll_receive_skb(struct sk_buff *skb)
-{
-	if (!list_empty(&skb->dev->napi_list))
-		return netpoll_rx(skb);
-	return 0;
-}
-
-#else
-static inline int netpoll_trap(void)
-{
-	return 0;
-}
-static inline void netpoll_set_trap(int trap)
-{
-}
-static inline bool netpoll_rx_processing(struct netpoll_info *npinfo)
-{
-	return false;
-}
-static inline bool netpoll_rx(struct sk_buff *skb)
-{
-	return false;
-}
-static inline bool netpoll_rx_on(struct sk_buff *skb)
-{
-	return false;
-}
-static inline int netpoll_receive_skb(struct sk_buff *skb)
-{
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_NETPOLL
 static inline void *netpoll_poll_lock(struct napi_struct *napi)
 {