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* [dpdk-stable] [PATCH v2] net/bnxt: fix doorbell write ordering
@ 2020-12-14 18:56 Lance Richardson
  2020-12-17 23:55 ` [dpdk-stable] [dpdk-dev] " Ajit Khaparde
  0 siblings, 1 reply; 2+ messages in thread
From: Lance Richardson @ 2020-12-14 18:56 UTC (permalink / raw)
  To: Ajit Khaparde, Somnath Kotur; +Cc: dev, ferruh.yigit, stable

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@broadcom.com>
Reviewed-by: Ajit Kumar Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Cc: stable@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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^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [dpdk-stable] [dpdk-dev] [PATCH v2] net/bnxt: fix doorbell write ordering
  2020-12-14 18:56 [dpdk-stable] [PATCH v2] net/bnxt: fix doorbell write ordering Lance Richardson
@ 2020-12-17 23:55 ` Ajit Khaparde
  0 siblings, 0 replies; 2+ messages in thread
From: Ajit Khaparde @ 2020-12-17 23:55 UTC (permalink / raw)
  To: Lance Richardson; +Cc: Ajit Khaparde, Somnath Kotur, dev, ferruh.yigit, stable

On Mon, Dec 14, 2020 at 10:56 AM Lance Richardson
<lance.richardson@broadcom.com> wrote:
>
> 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@broadcom.com>
> Reviewed-by: Ajit Kumar Khaparde <ajit.khaparde@broadcom.com>
> Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
> Cc: stable@dpdk.org

Patch applied to dpdk-next-net-brcm.

> ---
> 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
>
>
> --
> This electronic communication and the information and any files transmitted
> with it, or attached to it, are confidential and are intended solely for
> the use of the individual or entity to whom it is addressed and may contain
> information that is confidential, legally privileged, protected by privacy
> laws, or otherwise restricted from disclosure to anyone else. If you are
> not the intended recipient or the person responsible for delivering the
> e-mail to the intended recipient, you are hereby notified that any use,
> copying, distributing, dissemination, forwarding, printing, or copying of
> this e-mail is strictly prohibited. If you received this e-mail in error,
> please return the e-mail to the sender, delete it from your computer, and
> destroy any printed copy of it.



-- 
Ajit Khaparde

^ permalink raw reply	[flat|nested] 2+ messages in thread

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