From: Jason Wang <jasowang@redhat.com>
Date: Fri, 11 Aug 2017 19:41:17 +0800
Subject: net: export some generic xdp helpers
Patch-mainline: v4.14-rc1
Git-commit: 7c4974786f4794178f04e96318fc3b2f2850cbc6
References: bsc#1109837

This patch tries to export some generic xdp helpers to drivers. This
can let driver to do XDP for a specific skb. This is useful for the
case when the packet is hard to be processed at page level directly
(e.g jumbo/GSO frame).

With this patch, there's no need for driver to forbid the XDP set when
configuration is not suitable. Instead, it can defer the XDP for
packets that is hard to be processed directly after skb is created.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/netdevice.h |    2 ++
 net/core/dev.c            |   14 ++++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3251,6 +3251,8 @@ static inline void dev_consume_skb_any(s
 	__dev_kfree_skb_any(skb, SKB_REASON_CONSUMED);
 }
 
+void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog);
+int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb);
 int netif_rx(struct sk_buff *skb);
 int netif_rx_ni(struct sk_buff *skb);
 int netif_receive_skb(struct sk_buff *skb);
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3927,7 +3927,7 @@ static u32 netif_receive_generic_xdp(str
 /* When doing generic XDP we have to bypass the qdisc layer and the
  * network taps in order to match in-driver-XDP behavior.
  */
-static void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
+void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
 {
 	struct net_device *dev = skb->dev;
 	struct netdev_queue *txq;
@@ -3948,13 +3948,12 @@ static void generic_xdp_tx(struct sk_buf
 		kfree_skb(skb);
 	}
 }
+EXPORT_SYMBOL_GPL(generic_xdp_tx);
 
 static struct static_key generic_xdp_needed __read_mostly;
 
-static int do_xdp_generic(struct sk_buff *skb)
+int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
 {
-	struct bpf_prog *xdp_prog = rcu_dereference(skb->dev->xdp_prog);
-
 	if (xdp_prog) {
 		u32 act = netif_receive_generic_xdp(skb, xdp_prog);
 		int err;
@@ -3979,6 +3978,7 @@ out_redir:
 	kfree_skb(skb);
 	return XDP_DROP;
 }
+EXPORT_SYMBOL_GPL(do_xdp_generic);
 
 static int netif_rx_internal(struct sk_buff *skb)
 {
@@ -3989,7 +3989,8 @@ static int netif_rx_internal(struct sk_b
 	trace_netif_rx(skb);
 
 	if (static_key_false(&generic_xdp_needed)) {
-		int ret = do_xdp_generic(skb);
+		int ret = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog),
+					 skb);
 
 		/* Consider XDP consuming the packet a success from
 		 * the netdev point of view we do not want to count
@@ -4510,7 +4511,8 @@ static int netif_receive_skb_internal(st
 	rcu_read_lock();
 
 	if (static_key_false(&generic_xdp_needed)) {
-		int ret = do_xdp_generic(skb);
+		int ret = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog),
+					 skb);
 
 		if (ret != XDP_PASS) {
 			rcu_read_unlock();