af_packet: Add Queue mapping mode to af_packet fanout operation

This patch adds a queue mapping mode to the fanout operation of af_packet
sockets.  This allows user space af_packet users to better filter on flows
ingressing and egressing via a specific hardware queue, and avoids the potential
packet reordering that can occur when FANOUT_CPU is being used and irq affinity
varies.

Tested successfully by myself.  applies to net-next

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 97346162803d..6a2bb37506c5 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1312,6 +1312,13 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f,
         return idx;
 }
 
+static unsigned int fanout_demux_qm(struct packet_fanout *f,
+                                    struct sk_buff *skb,
+                                    unsigned int num)
+{
+        return skb_get_queue_mapping(skb) % num;
+}
+
 static bool fanout_has_flag(struct packet_fanout *f, u16 flag)
 {
         return f->flags & (flag >> 8);
@@ -1351,6 +1358,9 @@ static int packet_rcv_fanout(struct sk_buff *skb, struct net_device *dev,
         case PACKET_FANOUT_RND:
                 idx = fanout_demux_rnd(f, skb, num);
                 break;
+        case PACKET_FANOUT_QM:
+                idx = fanout_demux_qm(f, skb, num);
+                break;
         case PACKET_FANOUT_ROLLOVER:
                 idx = fanout_demux_rollover(f, skb, 0, (unsigned int) -1, num);
                 break;
@@ -1421,6 +1431,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
         case PACKET_FANOUT_LB:
         case PACKET_FANOUT_CPU:
         case PACKET_FANOUT_RND:
+        case PACKET_FANOUT_QM:
                 break;
         default:
                 return -EINVAL;