[v2] net/bnxt: fix doorbell write ordering
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Commit Message
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(-)
Comments
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
>
>
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@@ -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);