[PATCH] net: deliver skbs on inactive slaves to exact matches

[John Fastabend <john.r.fastabend@intel.com>]

Currently, the accelerated receive path for VLAN's will
drop packets if the real device is an inactive slave and
is not one of the special pkts tested for in
skb_bond_should_drop().  This behavior is different then
the non-accelerated path and for pkts over a bonded vlan.

For example,

vlanx -> bond0 -> ethx

will be dropped in the vlan path and not delivered to any
packet handlers.  However,

bond0 -> vlanx -> ethx

will be delivered to handlers that match the exact dev,
because the VLAN path checks the real_dev which is not a
slave and netif_recv_skb() doesn't drop frames but only
delivers them to exact matches.

This patch adds a pkt_type PACKET_DROP which is now used
to identify skbs that would previously been dropped and
allows the skb to continue to skb_netif_recv().  Here we
add logic to check for PACKET_DROP and if so only deliver
to handlers that match exactly.  IMHO this is more
consistent and gives pkt handlers a way to identify skbs
that come from inactive slaves.

This allows a third case to function which is important for
doing multipath with FCoE traffic while LAN traffic bonded,

bond0 -> ethx
          |
vlanx -> --

Here the vlan is not in bond0 but the FCoE handler can still
receive the skb.  Previously these skbs were dropped.

I have tested the following 4 configurations in failover modes
and load balancing modes and have not seen any duplicate packets
or unexpected bahavior.

# bond0 -> ethx

# vlanx -> bond0 -> ethx

# bond0 -> vlanx -> ethx

# bond0 -> ethx
            |
  vlanx -> --

Also this removes the PACKET_FASTROUTE define which was not being
used.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
---

 include/linux/if_packet.h |    2 +-
 net/8021q/vlan_core.c     |    4 ++--
 net/core/dev.c            |   25 ++++++++++++++++++-------
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 6ac23ef..9d079fa 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -28,7 +28,7 @@ struct sockaddr_ll {
 #define PACKET_OUTGOING		4		/* Outgoing of any type */
 /* These ones are invisible by user level */
 #define PACKET_LOOPBACK		5		/* MC/BRD frame looped back */
-#define PACKET_FASTROUTE	6		/* Fastrouted frame	*/
+#define PACKET_DROP		6		/* Drop packet 		*/
 
 /* Packet socket options */
 
diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index c584a0a..4510e08 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -12,7 +12,7 @@ int __vlan_hwaccel_rx(struct sk_buff *skb, struct vlan_group *grp,
 		return NET_RX_DROP;
 
 	if (skb_bond_should_drop(skb, ACCESS_ONCE(skb->dev->master)))
-		goto drop;
+		skb->pkt_type = PACKET_DROP;
 
 	skb->skb_iif = skb->dev->ifindex;
 	__vlan_hwaccel_put_tag(skb, vlan_tci);
@@ -84,7 +84,7 @@ vlan_gro_common(struct napi_struct *napi, struct vlan_group *grp,
 	struct sk_buff *p;
 
 	if (skb_bond_should_drop(skb, ACCESS_ONCE(skb->dev->master)))
-		goto drop;
+		skb->pkt_type = PACKET_DROP;
 
 	skb->skb_iif = skb->dev->ifindex;
 	__vlan_hwaccel_put_tag(skb, vlan_tci);
diff --git a/net/core/dev.c b/net/core/dev.c
index 36d53be..cefac4f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2776,7 +2776,7 @@ static int __netif_receive_skb(struct sk_buff *skb)
 	struct net_device *orig_dev;
 	struct net_device *master;
 	struct net_device *null_or_orig;
-	struct net_device *null_or_bond;
+	struct net_device *dev_or_bond;
 	int ret = NET_RX_DROP;
 	__be16 type;
 
@@ -2793,13 +2793,24 @@ static int __netif_receive_skb(struct sk_buff *skb)
 	if (!skb->skb_iif)
 		skb->skb_iif = skb->dev->ifindex;
 
+	/*
+	 * bonding note: skbs received on inactive slaves should only
+	 * be delivered to pkt handlers that are exact matches.  Also
+	 * the pkt_type field will be marked PACKET_DROP.  If packet
+	 * handlers are sensitive to duplicate packets these skbs will
+	 * need to be dropped at the handler.  The vlan accel path may
+	 * have already set PACKET_DROP.
+	 */
 	null_or_orig = NULL;
 	orig_dev = skb->dev;
 	master = ACCESS_ONCE(orig_dev->master);
-	if (master) {
-		if (skb_bond_should_drop(skb, master))
+	if (skb->pkt_type == PACKET_DROP)
+		null_or_orig = orig_dev;
+	else if (master) {
+		if (skb_bond_should_drop(skb, master)) {
+			skb->pkt_type = PACKET_DROP;
 			null_or_orig = orig_dev; /* deliver only exact match */
-		else
+		} else
 			skb->dev = master;
 	}
 
@@ -2849,10 +2860,10 @@ ncls:
 	 * device that may have registered for a specific ptype.  The
 	 * handler may have to adjust skb->dev and orig_dev.
 	 */
-	null_or_bond = NULL;
+	dev_or_bond = skb->dev;
 	if ((skb->dev->priv_flags & IFF_802_1Q_VLAN) &&
 	    (vlan_dev_real_dev(skb->dev)->priv_flags & IFF_BONDING)) {
-		null_or_bond = vlan_dev_real_dev(skb->dev);
+		dev_or_bond = vlan_dev_real_dev(skb->dev);
 	}
 
 	type = skb->protocol;
@@ -2860,7 +2871,7 @@ ncls:
 			&ptype_base[ntohs(type) & PTYPE_HASH_MASK], list) {
 		if (ptype->type == type && (ptype->dev == null_or_orig ||
 		     ptype->dev == skb->dev || ptype->dev == orig_dev ||
-		     ptype->dev == null_or_bond)) {
+		     ptype->dev == dev_or_bond)) {
 			if (pt_prev)
 				ret = deliver_skb(skb, pt_prev, orig_dev);
 			pt_prev = ptype;