[PATCH net-next 09/14] nfp: use AND instead of modulo to get ring indexes

[Jakub Kicinski]

We already force ring sizes to be power of 2 so replace
modulo operations with AND (size - 1) in index calculations.

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 drivers/net/ethernet/netronome/nfp/nfp_net_common.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c 
b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index b43d2dbae368..7225ab61a120 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -778,7 +778,7 @@ static int nfp_net_tx(struct sk_buff *skb, struct 
net_device *netdev)
        if (dma_mapping_error(&nn->pdev->dev, dma_addr))
                goto err_free;
 
-       wr_idx = tx_ring->wr_p % tx_ring->cnt;
+       wr_idx = tx_ring->wr_p & (tx_ring->cnt - 1);
 
        /* Stash the soft descriptor of the head then initialize it */
        txbuf = &tx_ring->txbufs[wr_idx];
@@ -822,7 +822,7 @@ static int nfp_net_tx(struct sk_buff *skb, struct 
net_device *netdev)
                        if (dma_mapping_error(&nn->pdev->dev, dma_addr))
                                goto err_unmap;
 
-                       wr_idx = (wr_idx + 1) % tx_ring->cnt;
+                       wr_idx = (wr_idx + 1) & (tx_ring->cnt - 1);
                        tx_ring->txbufs[wr_idx].skb = skb;
                        tx_ring->txbufs[wr_idx].dma_addr = dma_addr;
                        tx_ring->txbufs[wr_idx].fidx = f;
@@ -917,7 +917,7 @@ static void nfp_net_tx_complete(struct nfp_net_tx_ring 
*tx_ring)
                todo = qcp_rd_p + tx_ring->cnt - tx_ring->qcp_rd_p;
 
        while (todo--) {
-               idx = tx_ring->rd_p % tx_ring->cnt;
+               idx = tx_ring->rd_p & (tx_ring->cnt - 1);
                tx_ring->rd_p++;
 
                skb = tx_ring->txbufs[idx].skb;
@@ -992,7 +992,7 @@ static void nfp_net_tx_complete(struct nfp_net_tx_ring 
*tx_ring)
                int nr_frags, fidx, idx;
                struct sk_buff *skb;
 
-               idx = tx_ring->rd_p % tx_ring->cnt;
+               idx = tx_ring->rd_p & (tx_ring->cnt - 1);
                skb = tx_ring->txbufs[idx].skb;
                nr_frags = skb_shinfo(skb)->nr_frags;
                fidx = tx_ring->txbufs[idx].fidx;
@@ -1129,7 +1129,7 @@ static void nfp_net_rx_give_one(struct nfp_net_rx_ring 
*rx_ring,
 {
        unsigned int wr_idx;
 
-       wr_idx = rx_ring->wr_p % rx_ring->cnt;
+       wr_idx = rx_ring->wr_p & (rx_ring->cnt - 1);
 
        /* Stash SKB and DMA address away */
        rx_ring->rxbufs[wr_idx].frag = frag;
@@ -1164,7 +1164,7 @@ static void nfp_net_rx_ring_reset(struct nfp_net_rx_ring 
*rx_ring)
        unsigned int wr_idx, last_idx;
 
        /* Move the empty entry to the end of the list */
-       wr_idx = rx_ring->wr_p % rx_ring->cnt;
+       wr_idx = rx_ring->wr_p & (rx_ring->cnt - 1);
        last_idx = rx_ring->cnt - 1;
        rx_ring->rxbufs[wr_idx].dma_addr = rx_ring->rxbufs[last_idx].dma_addr;
        rx_ring->rxbufs[wr_idx].frag = rx_ring->rxbufs[last_idx].frag;
@@ -1413,7 +1413,7 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, 
int budget)
        int idx;
 
        while (pkts_polled < budget) {
-               idx = rx_ring->rd_p % rx_ring->cnt;
+               idx = rx_ring->rd_p & (rx_ring->cnt - 1);
 
                rxd = &rx_ring->rxds[idx];
                if (!(rxd->rxd.meta_len_dd & PCIE_DESC_RX_DD))
-- 
1.9.1