From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Mon, 15 May 2017 17:55:23 -0700
Subject: nfp: eliminate an if statement in calculation of completed frames
Patch-mainline: v4.13-rc1
Git-commit: 730b3ab54af4f816cdf541a23c879c9379a480db
References: bsc#1055968

Given that our rings are always a power of 2, we can simplify the
calculation of number of completed TX descriptors by using masking
instead of if statement based on whether the index have wrapped
or not.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/netronome/nfp/nfp_net_common.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -939,10 +939,7 @@ static void nfp_net_tx_complete(struct n
 	if (qcp_rd_p == tx_ring->qcp_rd_p)
 		return;
 
-	if (qcp_rd_p > tx_ring->qcp_rd_p)
-		todo = qcp_rd_p - tx_ring->qcp_rd_p;
-	else
-		todo = qcp_rd_p + tx_ring->cnt - tx_ring->qcp_rd_p;
+	todo = D_IDX(tx_ring, qcp_rd_p + tx_ring->cnt - tx_ring->qcp_rd_p);
 
 	while (todo--) {
 		idx = D_IDX(tx_ring, tx_ring->rd_p++);
@@ -1013,10 +1010,7 @@ static bool nfp_net_xdp_complete(struct
 	if (qcp_rd_p == tx_ring->qcp_rd_p)
 		return true;
 
-	if (qcp_rd_p > tx_ring->qcp_rd_p)
-		todo = qcp_rd_p - tx_ring->qcp_rd_p;
-	else
-		todo = qcp_rd_p + tx_ring->cnt - tx_ring->qcp_rd_p;
+	todo = D_IDX(tx_ring, qcp_rd_p + tx_ring->cnt - tx_ring->qcp_rd_p);
 
 	done_all = todo <= NFP_NET_XDP_MAX_COMPLETE;
 	todo = min(todo, NFP_NET_XDP_MAX_COMPLETE);