dpif-netdev: Check for PKT_RX_RSS_HASH flag.

DPDK mbufs contain a valid RSS hash only if PKT_RX_RSS_HASH is set in 'ol_flags'. Otherwise the hash is garbage and doesn't relate to the packet. This fixes an issue with vhost, which, being a virtual NIC, doesn't compute the hash. Reported-by: Dongjun <[email protected]> Suggested-by: Flavio Leitner <[email protected]> Acked-by: Kevin Traynor <[email protected]> Acked-by: Pravin B Shelar <[email protected]> Signed-off-by: Daniele Di Proietto <[email protected]>
dhanunjaya · Sep 11, 2015 · f2f44f5 · f2f44f5
1 parent 8f96455
commit f2f44f5
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Showing 6 changed files with 32 additions and 6 deletions.
diff --git 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
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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;
     }