[dpdk-dev] [PATCH v2] net/bnxt: fix doorbell write ordering

Lance Richardson lance.richardson at broadcom.com
Mon Dec 14 19:56:38 CET 2020


Write completion queue doorbell before receive descriptor
doorbell to avoid possibility of completion queue overflow
when completion queue size is equal to receive descriptor
ring size. Remove unnecessary compiler barriers (db write
functions have the necessary barriers.)

Fixes: 637e34befd9c ("net/bnxt: optimize Rx processing")
Signed-off-by: Lance Richardson <lance.richardson at broadcom.com>
Reviewed-by: Ajit Kumar Khaparde <ajit.khaparde at broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur at broadcom.com>
Cc: stable at dpdk.org
---
v2 - Fixed typo in commit log.

 drivers/net/bnxt/bnxt_rxr.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/bnxt/bnxt_rxr.c b/drivers/net/bnxt/bnxt_rxr.c
index e2d388e69f..ffdeeecc3a 100644
--- a/drivers/net/bnxt/bnxt_rxr.c
+++ b/drivers/net/bnxt/bnxt_rxr.c
@@ -917,17 +917,17 @@ uint16_t bnxt_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		goto done;
 	}
 
-	rte_compiler_barrier();
+	/* Ring the completion queue doorbell. */
+	bnxt_db_cq(cpr);
+
+	/* Ring the receive descriptor doorbell. */
 	if (rx_raw_prod != rxr->rx_raw_prod)
 		bnxt_db_write(&rxr->rx_db, rxr->rx_raw_prod);
 
-	rte_compiler_barrier();
 	/* Ring the AGG ring DB */
 	if (ag_raw_prod != rxr->ag_raw_prod)
 		bnxt_db_write(&rxr->ag_db, rxr->ag_raw_prod);
 
-	bnxt_db_cq(cpr);
-
 	/* Attempt to alloc Rx buf in case of a previous allocation failure. */
 	if (rc == -ENOMEM) {
 		int i = RING_NEXT(rx_raw_prod);
-- 
2.25.1


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