[ovs-dev,v3] dpif-netdev: Check for PKT_RX_RSS_HASH flag.

diff --git a/lib/dp-packet.h b/lib/dp-packet.h
index e4c2593..5044ce0 100644
--- a/lib/dp-packet.h
+++ b/lib/dp-packet.h
@@ -48,6 +48,7 @@  struct dp_packet {
     uint16_t data_ofs;          /* First byte actually in use. */
     uint32_t size_;             /* Number of bytes in use. */
     uint32_t rss_hash;          /* Packet hash. */
+    bool rss_hash_valid;        /* Is the 'rss_hash' valid? */
 #endif
     enum dp_packet_source source;  /* Source of memory allocated as 'base'. */
     uint8_t l2_pad_size;           /* Detected l2 padding size.
@@ -514,6 +515,8 @@  dp_packet_reset_packet(struct dp_packet *b, int off)
     b->l2_5_ofs = b->l3_ofs = b->l4_ofs = UINT16_MAX;
 }
 
+/* Returns the RSS hash of the packet 'p'.  Note that the returned value is
+ * correct only if 'dp_packet_rss_valid(p)' returns true */
 static inline uint32_t
 dp_packet_get_rss_hash(struct dp_packet *p)
 {
@@ -529,8 +532,30 @@  dp_packet_set_rss_hash(struct dp_packet *p, uint32_t hash)
 {
 #ifdef DPDK_NETDEV
     p->mbuf.hash.rss = hash;
+    p->mbuf.ol_flags |= PKT_RX_RSS_HASH;
 #else
     p->rss_hash = hash;
+    p->rss_hash_valid = true;
+#endif
+}
+
+static inline bool
+dp_packet_rss_valid(struct dp_packet *p)
+{
+#ifdef DPDK_NETDEV
+    return p->mbuf.ol_flags & PKT_RX_RSS_HASH;
+#else
+    return p->rss_hash_valid;
+#endif
+}
+
+static inline void
+dp_packet_rss_invalidate(struct dp_packet *p)
+{
+#ifdef DPDK_NETDEV
+    p->mbuf.ol_flags &= ~PKT_RX_RSS_HASH;
+#else
+    p->rss_hash_valid = false;
 #endif
 }
 
diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index db76290..446f386 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -3100,8 +3100,9 @@  dpif_netdev_packet_get_rss_hash(struct dp_packet *packet,
 {
     uint32_t hash, recirc_depth;
 
-    hash = dp_packet_get_rss_hash(packet);
-    if (OVS_UNLIKELY(!hash)) {
+    if (OVS_LIKELY(dp_packet_rss_valid(packet))) {
+        hash = dp_packet_get_rss_hash(packet);
+    } else {
         hash = miniflow_hash_5tuple(mf, 0);
         dp_packet_set_rss_hash(packet, hash);
     }
diff --git a/lib/netdev-bsd.c b/lib/netdev-bsd.c
index f755475..60e5615 100644
--- a/lib/netdev-bsd.c
+++ b/lib/netdev-bsd.c
@@ -643,7 +643,7 @@  netdev_bsd_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet **packets,
         dp_packet_delete(packet);
     } else {
         dp_packet_pad(packet);
-        dp_packet_set_rss_hash(packet, 0);
+        dp_packet_rss_invalidate(packet);
         packets[0] = packet;
         *c = 1;
     }
diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
index 5bad7e0..e4e3d2c 100644
--- a/lib/netdev-dpdk.c
+++ b/lib/netdev-dpdk.c
@@ -2001,7 +2001,7 @@  netdev_dpdk_ring_send(struct netdev *netdev_, int qid,
      * the consumer of the ring and return into the datapath without recalculating
      * the RSS hash. */
     for (i = 0; i < cnt; i++) {
-        dp_packet_set_rss_hash(pkts[i], 0);
+        dp_packet_rss_invalidate(pkts[i]);
     }
 
     netdev_dpdk_send__(netdev, qid, pkts, cnt, may_steal);
diff --git a/lib/netdev-dummy.c b/lib/netdev-dummy.c
index 9946d5a..76815c2 100644
--- a/lib/netdev-dummy.c
+++ b/lib/netdev-dummy.c
@@ -855,7 +855,7 @@  netdev_dummy_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet **arr,
     ovs_mutex_unlock(&netdev->mutex);
 
     dp_packet_pad(packet);
-    dp_packet_set_rss_hash(packet, 0);
+    dp_packet_rss_invalidate(packet);
 
     arr[0] = packet;
     *c = 1;
diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c
index 2b54c6a..584e804 100644
--- a/lib/netdev-linux.c
+++ b/lib/netdev-linux.c
@@ -1076,7 +1076,7 @@  netdev_linux_rxq_recv(struct netdev_rxq *rxq_, struct dp_packet **packets,
         dp_packet_delete(buffer);
     } else {
         dp_packet_pad(buffer);
-        dp_packet_set_rss_hash(buffer, 0);
+        dp_packet_rss_invalidate(buffer);
         packets[0] = buffer;
         *c = 1;
     }