[PATCH RFC ipsec-next 4/5] net: Prepare for IPsec GRO

[Steffen Klassert <steffen.klassert@secunet.com>]

This patch prepares the generic codepath for IPsec GRO.
We introduce a new GRO_CONSUMED notifier to reflect that
IPsec can return asynchronous. On IPsec GRO we grab the
packet and reinject it back to layer 2 after IPsec
processing. We also use one xfrm_gro bit on the sk_buff
that will be set from IPsec to notify about GRO. If this
bit is set, we call napi_gro_receive for the backlog device
instead of __netif_receive_skb.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 include/linux/netdevice.h |  1 +
 include/linux/skbuff.h    | 14 +++++++++++++-
 net/core/dev.c            | 17 ++++++++++++++++-
 net/xfrm/Kconfig          |  4 ++++
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ecd78b3..89bad76 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -352,6 +352,7 @@ enum gro_result {
 	GRO_HELD,
 	GRO_NORMAL,
 	GRO_DROP,
+	GRO_CONSUMED,
 };
 typedef enum gro_result gro_result_t;
 
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b53c0cf..a78cd90 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -749,7 +749,10 @@ struct sk_buff {
 #ifdef CONFIG_NET_SWITCHDEV
 	__u8			offload_fwd_mark:1;
 #endif
-	/* 2, 4 or 5 bit hole */
+#ifdef CONFIG_XFRM_OFFLOAD
+	__u8			xfrm_gro:1;
+#endif
+	/* 1 to 5 bits hole */
 
 #ifdef CONFIG_NET_SCHED
 	__u16			tc_index;	/* traffic control index */
@@ -3698,6 +3701,15 @@ static inline struct sec_path *skb_sec_path(struct sk_buff *skb)
 #endif
 }
 
+static inline bool skb_xfrm_gro(struct sk_buff *skb)
+{
+#ifdef CONFIG_XFRM_OFFLOAD
+	return skb->xfrm_gro;
+#else
+	return false;
+#endif
+}
+
 /* Keeps track of mac header offset relative to skb->head.
  * It is useful for TSO of Tunneling protocol. e.g. GRE.
  * For non-tunnel skb it points to skb_mac_header() and for
diff --git a/net/core/dev.c b/net/core/dev.c
index 56818f7..ecbaaf7f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4525,6 +4525,11 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 	}
 	rcu_read_unlock();
 
+	if (PTR_ERR(pp) == -EINPROGRESS) {
+		ret = GRO_CONSUMED;
+		goto ok;
+	}
+
 	if (&ptype->list == head)
 		goto normal;
 
@@ -4623,6 +4628,9 @@ static gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
 	case GRO_MERGED_FREE:
 		if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD) {
 			skb_dst_drop(skb);
+#ifdef CONFIG_XFRM_OFFLOAD
+			secpath_put(skb->sp);
+#endif
 			kmem_cache_free(skbuff_head_cache, skb);
 		} else {
 			__kfree_skb(skb);
@@ -4631,6 +4639,7 @@ static gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
 
 	case GRO_HELD:
 	case GRO_MERGED:
+	case GRO_CONSUMED:
 		break;
 	}
 
@@ -4701,6 +4710,7 @@ static gro_result_t napi_frags_finish(struct napi_struct *napi,
 		break;
 
 	case GRO_MERGED:
+	case GRO_CONSUMED:
 		break;
 	}
 
@@ -4843,7 +4853,12 @@ static int process_backlog(struct napi_struct *napi, int quota)
 
 		while ((skb = __skb_dequeue(&sd->process_queue))) {
 			rcu_read_lock();
-			__netif_receive_skb(skb);
+
+			if (skb_xfrm_gro(skb))
+				napi_gro_receive(napi, skb);
+			else
+				__netif_receive_skb(skb);
+
 			rcu_read_unlock();
 			input_queue_head_incr(sd);
 			if (++work >= quota)
diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig
index bda1a13..442ac61 100644
--- a/net/xfrm/Kconfig
+++ b/net/xfrm/Kconfig
@@ -5,6 +5,10 @@ config XFRM
        bool
        depends on NET
 
+config XFRM_OFFLOAD
+	bool
+	depends on XFRM
+
 config XFRM_ALGO
 	tristate
 	select XFRM
-- 
1.9.1