netdev - [PATCH net-next 13/18] net: Add offload kernel net stack packet type

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Date:	Fri, 17 Jun 2016 17:43:54 +0300
From:	Saeed Mahameed <saeedm@...lanox.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, Doug Ledford <dledford@...hat.com>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Maor Gottlieb <maorg@...lanox.com>,
	Huy Nguyen <huyn@...lanox.com>, Tal Alon <talal@...lanox.com>,
	Patrick McHardy <kaber@...sh.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Saeed Mahameed <saeedm@...lanox.com>
Subject: [PATCH net-next 13/18] net: Add offload kernel net stack packet type

From: Maor Gottlieb <maorg@...lanox.com>

Add new packet type to skip kernel specific protocol handlers.

This is needed so device drivers can pass packets up to user space
(af_packet/tcpdump, etc..) without the need for them to go through
the whole kernel data path.

Signed-off-by: Maor Gottlieb <maorg@...lanox.com>
CC: David S. Miller <davem@...emloft.net>
CC: Patrick McHardy <kaber@...sh.net>
CC: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 include/linux/skbuff.h         | 6 +++---
 include/uapi/linux/if_packet.h | 1 +
 net/core/dev.c                 | 4 ++++
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index dc0fca7..359724e 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -694,14 +694,14 @@ struct sk_buff {
 
 /* if you move pkt_type around you also must adapt those constants */
 #ifdef __BIG_ENDIAN_BITFIELD
-#define PKT_TYPE_MAX	(7 << 5)
+#define PKT_TYPE_MAX	(8 << 5)
 #else
-#define PKT_TYPE_MAX	7
+#define PKT_TYPE_MAX	8
 #endif
 #define PKT_TYPE_OFFSET()	offsetof(struct sk_buff, __pkt_type_offset)
 
 	__u8			__pkt_type_offset[0];
-	__u8			pkt_type:3;
+	__u8			pkt_type:4;
 	__u8			pfmemalloc:1;
 	__u8			ignore_df:1;
 	__u8			nfctinfo:3;
diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
index 9e7edfd..93a9f13 100644
--- a/include/uapi/linux/if_packet.h
+++ b/include/uapi/linux/if_packet.h
@@ -29,6 +29,7 @@ struct sockaddr_ll {
 #define PACKET_LOOPBACK		5		/* MC/BRD frame looped back */
 #define PACKET_USER		6		/* To user space	*/
 #define PACKET_KERNEL		7		/* To kernel space	*/
+#define PACKET_OFFLOAD_KERNEL	8		/* Offload NET stack	*/
 /* Unused, PACKET_FASTROUTE and PACKET_LOOPBACK are invisible to user space */
 #define PACKET_FASTROUTE	6		/* Fastrouted frame	*/
 
diff --git a/net/core/dev.c b/net/core/dev.c
index d40593b..f300f1a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4113,6 +4113,9 @@ another_round:
 		pt_prev = ptype;
 	}
 
+	if (unlikely(skb->pkt_type == PACKET_OFFLOAD_KERNEL))
+		goto done;
+
 skip_taps:
 #ifdef CONFIG_NET_INGRESS
 	if (static_key_false(&ingress_needed)) {
@@ -4190,6 +4193,7 @@ ncls:
 				       &skb->dev->ptype_specific);
 	}
 
+done:
 	if (pt_prev) {
 		if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
 			goto drop;
-- 
2.8.0