[dpdk-dev] [PATCH v2 1/4] net/ena: fix incorrect Rx descriptors allocation

[Marcin Wojtas <mw@semihalf.com>]

From: Michal Krawczyk <mk@semihalf.com>

When application tried to allocate 1024 descriptors, device was not
initializing properly.

This patch solves it by avoiding allocation of all descriptors in the
ring in one attempt. At least one descriptor must remain unused in the
HW ring.

Fixes: 1173fca25af9 ("ena: add polling-mode driver")

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
---
 drivers/net/ena/ena_ethdev.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index b5e6db6..90cf2ad 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -919,7 +919,7 @@ static int ena_start(struct rte_eth_dev *dev)
 
 static int ena_queue_restart(struct ena_ring *ring)
 {
-	int rc;
+	int rc, bufs_num;
 
 	ena_assert_msg(ring->configured == 1,
 		       "Trying to restart unconfigured queue\n");
@@ -930,8 +930,9 @@ static int ena_queue_restart(struct ena_ring *ring)
 	if (ring->type == ENA_RING_TYPE_TX)
 		return 0;
 
-	rc = ena_populate_rx_queue(ring, ring->ring_size);
-	if ((unsigned int)rc != ring->ring_size) {
+	bufs_num = ring->ring_size - 1;
+	rc = ena_populate_rx_queue(ring, bufs_num);
+	if (rc != bufs_num) {
 		PMD_INIT_LOG(ERR, "Failed to populate rx ring !");
 		return (-1);
 	}
@@ -1143,7 +1144,7 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 		return 0;
 
 	in_use = rxq->next_to_use - rxq->next_to_clean;
-	ena_assert_msg(((in_use + count) <= ring_size), "bad ring state");
+	ena_assert_msg(((in_use + count) < ring_size), "bad ring state");
 
 	count = RTE_MIN(count,
 			(uint16_t)(ring_size - (next_to_use & ring_mask)));
@@ -1574,6 +1575,7 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		recv_idx++;
 	}
 
+	desc_in_use += 1;
 	/* Burst refill to save doorbells, memory barriers, const interval */
 	if (ring_size - desc_in_use > ENA_RING_DESCS_RATIO(ring_size))
 		ena_populate_rx_queue(rx_ring, ring_size - desc_in_use);
-- 
1.8.3.1