net/pcap: remove Rx queue argument necessity

Previously in the PCAP PMD queues has to be defined as RxQ and TxQ
pairs, even if the need is only Rx or only Tx:
 "--vdev net_pcap0,tx_pcap=tx.pcap,rx_pcap=rx.pcap"

Following commit enabled only providing Rx queue, and if Tx queue is
not provided PMD drops the Tx packets automatically:
Commit a3f5252e5cbd ("net/pcap: enable infinitely Rx a pcap file")
 "--vdev net_pcap0,rx_pcap=rx.pcap"

This commit enables same thing for Rx queue, user no more have to
provide a Rx queue (rx_iface or rx_pcap), for this case a dummy Rx
burst function is used which doesn't return any packet at all:
 "--vdev net_pcap0,tx_pcap=tx.pcap"

This makes only saving packets to a pcap file use case easy.

When both Rx and Tx queues are missing PMD will return an error.
(Single interface is still supported: "--vdev net_pcap0,iface=eth0")

Signed-off-by: Aideen McLoughlin <aideen.mcloughlin@intel.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>

diff --git a/doc/guides/nics/pcap_ring.rst b/doc/guides/nics/pcap_ring.rst
index fb88fa6..cf230ae 100644 (file)
--- a/doc/guides/nics/pcap_ring.rst
+++ b/doc/guides/nics/pcap_ring.rst
@@ -126,6 +126,14 @@ Runtime Config Options
 
  In this case, one tx drop queue is created for each rxq on that device.
 
+ - Receive no packets on Rx
+
+ The user may want to run without receiving any packets on Rx. This can be done by not providing a rx_pcap or rx_iface, for example::
+
+   --vdev 'net_pcap0,tx_pcap=file_tx.pcap'
+
+In this case, one dummy rx queue is created for each tx queue argument passed
+
 Examples of Usage
 ^^^^^^^^^^^^^^^^^
 

diff --git a/doc/guides/rel_notes/release_19_08.rst b/doc/guides/rel_notes/release_19_08.rst
index 60992ce..b36cbd6 100644 (file)
--- a/doc/guides/rel_notes/release_19_08.rst
+++ b/doc/guides/rel_notes/release_19_08.rst
@@ -145,6 +145,12 @@ New Features
   device to be received repeatedly at a high rate. This can be useful for quick
   performance testing of DPDK apps.
 
+* **Enabled Receiving no packet on PCAP Rx.**
+
+  Added function to allow users to run without receiving any packets on PCAP Rx.
+  When function is called, a dummy queue is created for each Tx queue argument
+  passed.
+
 * **Added a FPGA_LTE_FEC bbdev PMD.**
 
   Added the new ``fpga_lte_fec`` bbdev driver for the Intel® FPGA PAC

diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
index d0e79aa..322c18f 100644 (file)
--- a/drivers/net/pcap/rte_eth_pcap.c
+++ b/drivers/net/pcap/rte_eth_pcap.c
@@ -112,6 +112,8 @@ struct pmd_devargs_all {
        int single_iface;
        unsigned int is_tx_pcap;
        unsigned int is_tx_iface;
+       unsigned int is_rx_pcap;
+       unsigned int is_rx_iface;
        unsigned int infinite_rx;
 };
 
@@ -295,6 +297,14 @@ eth_pcap_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
        return num_rx;
 }
 
+static uint16_t
+eth_null_rx(void *queue __rte_unused,
+               struct rte_mbuf **bufs __rte_unused,
+               uint16_t nb_pkts __rte_unused)
+{
+       return 0;
+}
+
 static inline void
 calculate_timestamp(struct timeval *ts) {
        uint64_t cycles;
@@ -1312,8 +1322,11 @@ eth_from_pcaps(struct rte_vdev_device *vdev,
        /* Assign rx ops. */
        if (infinite_rx)
                eth_dev->rx_pkt_burst = eth_pcap_rx_infinite;
-       else
+       else if (devargs_all->is_rx_pcap || devargs_all->is_rx_iface ||
+                       single_iface)
                eth_dev->rx_pkt_burst = eth_pcap_rx;
+       else
+               eth_dev->rx_pkt_burst = eth_null_rx;
 
        /* Assign tx ops. */
        if (devargs_all->is_tx_pcap)
@@ -1331,13 +1344,12 @@ static int
 pmd_pcap_probe(struct rte_vdev_device *dev)
 {
        const char *name;
-       unsigned int is_rx_pcap = 0;
        struct rte_kvargs *kvlist;
        struct pmd_devargs pcaps = {0};
        struct pmd_devargs dumpers = {0};
        struct rte_eth_dev *eth_dev =  NULL;
        struct pmd_internals *internal;
-       int ret;
+       int ret = 0;
 
        struct pmd_devargs_all devargs_all = {
                .single_iface = 0,
@@ -1400,13 +1412,22 @@ pmd_pcap_probe(struct rte_vdev_device *dev)
        }
 
        /*
-        * We check whether we want to open a RX stream from a real NIC or a
-        * pcap file
+        * We check whether we want to open a RX stream from a real NIC, a
+        * pcap file or open a dummy RX stream
         */
-       is_rx_pcap = rte_kvargs_count(kvlist, ETH_PCAP_RX_PCAP_ARG) ? 1 : 0;
+       devargs_all.is_rx_pcap =
+               rte_kvargs_count(kvlist, ETH_PCAP_RX_PCAP_ARG) ? 1 : 0;
+       devargs_all.is_rx_iface =
+               rte_kvargs_count(kvlist, ETH_PCAP_RX_IFACE_ARG) ? 1 : 0;
        pcaps.num_of_queue = 0;
 
-       if (is_rx_pcap) {
+       devargs_all.is_tx_pcap =
+               rte_kvargs_count(kvlist, ETH_PCAP_TX_PCAP_ARG) ? 1 : 0;
+       devargs_all.is_tx_iface =
+               rte_kvargs_count(kvlist, ETH_PCAP_TX_IFACE_ARG) ? 1 : 0;
+       dumpers.num_of_queue = 0;
+
+       if (devargs_all.is_rx_pcap) {
                /*
                 * We check whether we want to infinitely rx the pcap file.
                 */
@@ -1432,11 +1453,29 @@ pmd_pcap_probe(struct rte_vdev_device *dev)
 
                ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_PCAP_ARG,
                                &open_rx_pcap, &pcaps);
-       } else {
+       } else if (devargs_all.is_rx_iface) {
                ret = rte_kvargs_process(kvlist, NULL,
                                &rx_iface_args_process, &pcaps);
-       }
+       } else if (devargs_all.is_tx_iface || devargs_all.is_tx_pcap) {
+               unsigned int i;
+
+               /* Count number of tx queue args passed before dummy rx queue
+                * creation so a dummy rx queue can be created for each tx queue
+                */
+               unsigned int num_tx_queues =
+                       (rte_kvargs_count(kvlist, ETH_PCAP_TX_PCAP_ARG) +
+                       rte_kvargs_count(kvlist, ETH_PCAP_TX_IFACE_ARG));
 
+               PMD_LOG(INFO, "Creating null rx queue since no rx queues were provided.");
+
+               /* Creating a dummy rx queue for each tx queue passed */
+               for (i = 0; i < num_tx_queues; i++)
+                       ret = add_queue(&pcaps, "dummy_rx", "rx_null", NULL,
+                                       NULL);
+       } else {
+               PMD_LOG(ERR, "Error - No rx or tx queues provided");
+               ret = -ENOENT;
+       }
        if (ret < 0)
                goto free_kvlist;
 
@@ -1444,12 +1483,6 @@ pmd_pcap_probe(struct rte_vdev_device *dev)
         * We check whether we want to open a TX stream to a real NIC,
         * a pcap file, or drop packets on tx
         */
-       devargs_all.is_tx_pcap =
-               rte_kvargs_count(kvlist, ETH_PCAP_TX_PCAP_ARG) ? 1 : 0;
-       devargs_all.is_tx_iface =
-               rte_kvargs_count(kvlist, ETH_PCAP_TX_IFACE_ARG) ? 1 : 0;
-       dumpers.num_of_queue = 0;
-
        if (devargs_all.is_tx_pcap) {
                ret = rte_kvargs_process(kvlist, ETH_PCAP_TX_PCAP_ARG,
                                &open_tx_pcap, &dumpers);
@@ -1463,7 +1496,7 @@ pmd_pcap_probe(struct rte_vdev_device *dev)
 
                /* Add 1 dummy queue per rxq which counts and drops packets. */
                for (i = 0; i < pcaps.num_of_queue; i++)
-                       ret = add_queue(&dumpers, "dummy", "tx_drop", NULL,
+                       ret = add_queue(&dumpers, "dummy_tx", "tx_drop", NULL,
                                        NULL);
        }