[dpdk-dev] [PATCH v4 1/7] ethdev: Allow zero rx/tx queues in SRIOV mode

[Pawel Wodkowski <pawelx.wodkowski@intel.com>]

Allow zero rx/tx queues to be passed to rte_eth_dev_configure(). This
way PF might be used only for configuration purpose when no receive
and/or transmit functionality is needed.

Rationale:
in SRIOV mode PF use first free VF to RX/TX (at least ixgbe based NICs).
For example: if using 82599EB based NIC and VF count is 16, 32 or 64 all
recources are assigned to VFs so PF might be used only for configuration
purpose.

Signed-off-by: Pawel Wodkowski <pawelx.wodkowski@intel.com>
---
 lib/librte_ether/rte_ethdev.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
index ea3a1fb..2e814db 100644
--- a/lib/librte_ether/rte_ethdev.c
+++ b/lib/librte_ether/rte_ethdev.c
@@ -333,7 +333,7 @@ rte_eth_dev_rx_queue_config(struct rte_eth_dev *dev, uint16_t nb_queues)
 		dev->data->rx_queues = rte_zmalloc("ethdev->rx_queues",
 				sizeof(dev->data->rx_queues[0]) * nb_queues,
 				RTE_CACHE_LINE_SIZE);
-		if (dev->data->rx_queues == NULL) {
+		if (dev->data->rx_queues == NULL && nb_queues > 0) {
 			dev->data->nb_rx_queues = 0;
 			return -(ENOMEM);
 		}
@@ -475,7 +475,7 @@ rte_eth_dev_tx_queue_config(struct rte_eth_dev *dev, uint16_t nb_queues)
 		dev->data->tx_queues = rte_zmalloc("ethdev->tx_queues",
 				sizeof(dev->data->tx_queues[0]) * nb_queues,
 				RTE_CACHE_LINE_SIZE);
-		if (dev->data->tx_queues == NULL) {
+		if (dev->data->tx_queues == NULL && nb_queues > 0) {
 			dev->data->nb_tx_queues = 0;
 			return -(ENOMEM);
 		}
@@ -731,7 +731,10 @@ rte_eth_dev_configure(uint8_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 	}
 	if (nb_rx_q == 0) {
 		PMD_DEBUG_TRACE("ethdev port_id=%d nb_rx_q == 0\n", port_id);
-		return (-EINVAL);
+		/* In SRIOV there can be no free resource for PF. So permit use only
+		 * for configuration. */
+		if (RTE_ETH_DEV_SRIOV(dev).active == 0)
+			return (-EINVAL);
 	}
 
 	if (nb_tx_q > dev_info.max_tx_queues) {
@@ -739,9 +742,13 @@ rte_eth_dev_configure(uint8_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 				port_id, nb_tx_q, dev_info.max_tx_queues);
 		return (-EINVAL);
 	}
+
 	if (nb_tx_q == 0) {
 		PMD_DEBUG_TRACE("ethdev port_id=%d nb_tx_q == 0\n", port_id);
-		return (-EINVAL);
+		/* In SRIOV there can be no free resource for PF. So permit use only
+		 * for configuration. */
+		if (RTE_ETH_DEV_SRIOV(dev).active == 0)
+			return (-EINVAL);
 	}
 
 	/* Copy the dev_conf parameter into the dev structure */
-- 
1.9.1