[dpdk-stable] [PATCH 2/2] net/ena: fix delayed cleanup of Rx descriptors

[Michal Krawczyk]

[ backported from upstream commit ec78af6bc0556cf2a1133185ca33fb835b38afe0 ]

On RX path, after receiving bunch of packets, variable tracking
available descriptors in HW queue was not updated.

To fix this issue, variable tracking used descriptors must be updated
after receiving packets - it must be reduced by the amount of received
descriptors in current batch.

Additionally, variable next_to_clean in rx_ring must be updated before
entering ena_populate_rx_queue() to keep it up to date with the current
ring state.

Fixes: 1daff5260ff8 ("net/ena: use unmasked head and tail")
Cc: stable at dpdk.org

Signed-off-by: Michal Krawczyk <mk at semihalf.com>
Reviewed-by: Jakub Palider <jpalider at gmail.com>
Acked-by: Jan Medala <jan.medala at outlook.com>
---
 drivers/net/ena/ena_ethdev.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index f24fd26..1fc3654 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -1559,13 +1559,13 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		recv_idx++;
 	}
 
-	desc_in_use += 1;
+	rx_ring->next_to_clean = next_to_clean;
+
+	desc_in_use = desc_in_use - completed + 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);
 
-	rx_ring->next_to_clean = next_to_clean;
-
 	return recv_idx;
 }
 
-- 
2.7.4