netdev: Improve comments on netdev_rxq_recv().

[cascardo/ovs.git] / lib / netdev.c

diff --git a/lib/netdev.c b/lib/netdev.c
index e3b70b1..150f8d8 100644 (file)
--- a/lib/netdev.c
+++ b/lib/netdev.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2016 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -106,6 +106,12 @@ netdev_n_rxq(const struct netdev *netdev)
     return netdev->n_rxq;
 }
 
+int
+netdev_requested_n_rxq(const struct netdev *netdev)
+{
+    return netdev->requested_n_rxq;
+}
+
 bool
 netdev_is_pmd(const struct netdev *netdev)
 {
@@ -376,6 +382,7 @@ netdev_open(const char *name, const char *type, struct netdev **netdevp)
                 /* By default enable one tx and rx queue per netdev. */
                 netdev->n_txq = netdev->netdev_class->send ? 1 : 0;
                 netdev->n_rxq = netdev->netdev_class->rxq_alloc ? 1 : 0;
+                netdev->requested_n_rxq = netdev->n_rxq;
 
                 list_init(&netdev->saved_flags_list);
 
@@ -632,28 +639,28 @@ netdev_rxq_close(struct netdev_rxq *rx)
     }
 }
 
-/* Attempts to receive batch of packets from 'rx'.
- *
- * Returns EAGAIN immediately if no packet is ready to be received.
+/* Attempts to receive a batch of packets from 'rx'.  'pkts' should point to
+ * the beginning of an array of MAX_RX_BATCH pointers to dp_packet.  If
+ * successful, this function stores pointers to up to MAX_RX_BATCH dp_packets
+ * into the array, transferring ownership of the packets to the caller, stores
+ * the number of received packets into '*cnt', and returns 0.
  *
- * Returns EMSGSIZE, and discards the packet, if the received packet is longer
- * than 'dp_packet_tailroom(buffer)'.
+ * The implementation does not necessarily initialize any non-data members of
+ * 'pkts'.  That is, the caller must initialize layer pointers and metadata
+ * itself, if desired, e.g. with pkt_metadata_init() and miniflow_extract().
  *
- * It is advised that the tailroom of 'buffer' should be
- * VLAN_HEADER_LEN bytes longer than the MTU to allow space for an
- * out-of-band VLAN header to be added to the packet.  At the very least,
- * 'buffer' must have at least ETH_TOTAL_MIN bytes of tailroom.
- *
- * This function may be set to null if it would always return EOPNOTSUPP
- * anyhow. */
+ * Returns EAGAIN immediately if no packet is ready to be received or another
+ * positive errno value if an error was encountered. */
 int
-netdev_rxq_recv(struct netdev_rxq *rx, struct dp_packet **buffers, int *cnt)
+netdev_rxq_recv(struct netdev_rxq *rx, struct dp_packet **pkts, int *cnt)
 {
     int retval;
 
-    retval = rx->netdev->netdev_class->rxq_recv(rx, buffers, cnt);
+    retval = rx->netdev->netdev_class->rxq_recv(rx, pkts, cnt);
     if (!retval) {
         COVERAGE_INC(netdev_received);
+    } else {
+        *cnt = 0;
     }
     return retval;
 }
@@ -721,7 +728,9 @@ netdev_set_multiq(struct netdev *netdev, unsigned int n_txq,
  * If the function returns a non-zero value, some of the packets might have
  * been sent anyway.
  *
- * To retain ownership of 'buffer' caller can set may_steal to false.
+ * If 'may_steal' is false, the caller retains ownership of all the packets.
+ * If 'may_steal' is true, the caller transfers ownership of all the packets
+ * to the network device, regardless of success.
  *
  * The network device is expected to maintain one or more packet
  * transmission queues, so that the caller does not ordinarily have to
@@ -735,11 +744,17 @@ int
 netdev_send(struct netdev *netdev, int qid, struct dp_packet **buffers,
             int cnt, bool may_steal)
 {
-    int error;
+    if (!netdev->netdev_class->send) {
+        if (may_steal) {
+            for (int i = 0; i < cnt; i++) {
+                dp_packet_delete(buffers[i]);
+            }
+        }
+        return EOPNOTSUPP;
+    }
 
-    error = (netdev->netdev_class->send
-             ? netdev->netdev_class->send(netdev, qid, buffers, cnt, may_steal)
-             : EOPNOTSUPP);
+    int error = netdev->netdev_class->send(netdev, qid, buffers, cnt,
+                                           may_steal);
     if (!error) {
         COVERAGE_INC(netdev_sent);
     }
@@ -1800,6 +1815,12 @@ netdev_rxq_get_name(const struct netdev_rxq *rx)
     return netdev_get_name(netdev_rxq_get_netdev(rx));
 }
 
+int
+netdev_rxq_get_queue_id(const struct netdev_rxq *rx)
+{
+    return rx->queue_id;
+}
+
 static void
 restore_all_flags(void *aux OVS_UNUSED)
 {