From 61fafca768b24acbdc07cdf42ef18f50fd04fbbf Mon Sep 17 00:00:00 2001
From: Michal Krawczyk <mk@semihalf.com>
Date: Wed, 8 Apr 2020 10:29:17 +0200
Subject: [PATCH 047/107] net/ena: use macros for ring index operations

To improve code readability, abstraction was added for operating on IO
rings indexes.

Driver was defining local variable for ring mask in each function that
needed to operate on the ring indexes. Now it is being stored in the
ring as this value won't change unless size of the ring will change and
macros for advancing indexes using the mask has been added.

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Guy Tzalik <gtzalik@amazon.com>
---
 drivers/net/ena/ena_ethdev.c | 53 ++++++++++++++++++------------------
 drivers/net/ena/ena_ethdev.h |  4 +++
 2 files changed, 30 insertions(+), 27 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index 8c9856a1f7..d6f418c45b 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -1267,6 +1267,7 @@ static int ena_tx_queue_setup(struct rte_eth_dev *dev,
 	txq->next_to_clean = 0;
 	txq->next_to_use = 0;
 	txq->ring_size = nb_desc;
+	txq->size_mask = nb_desc - 1;
 	txq->numa_socket_id = socket_id;
 
 	txq->tx_buffer_info = rte_zmalloc("txq->tx_buffer_info",
@@ -1362,6 +1363,7 @@ static int ena_rx_queue_setup(struct rte_eth_dev *dev,
 	rxq->next_to_clean = 0;
 	rxq->next_to_use = 0;
 	rxq->ring_size = nb_desc;
+	rxq->size_mask = nb_desc - 1;
 	rxq->numa_socket_id = socket_id;
 	rxq->mb_pool = mp;
 
@@ -1410,8 +1412,6 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 {
 	unsigned int i;
 	int rc;
-	uint16_t ring_size = rxq->ring_size;
-	uint16_t ring_mask = ring_size - 1;
 	uint16_t next_to_use = rxq->next_to_use;
 	uint16_t in_use, req_id;
 	struct rte_mbuf **mbufs = rxq->rx_refill_buffer;
@@ -1419,9 +1419,10 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 	if (unlikely(!count))
 		return 0;
 
-	in_use = ring_size - ena_com_free_q_entries(rxq->ena_com_io_sq) - 1;
-
-	ena_assert_msg(((in_use + count) < ring_size), "bad ring state\n");
+	in_use = rxq->ring_size - 1 -
+		ena_com_free_q_entries(rxq->ena_com_io_sq);
+	ena_assert_msg(((in_use + count) < rxq->ring_size),
+		"bad ring state\n");
 
 	/* get resources for incoming packets */
 	rc = rte_mempool_get_bulk(rxq->mb_pool, (void **)mbufs, count);
@@ -1433,7 +1434,6 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 	}
 
 	for (i = 0; i < count; i++) {
-		uint16_t next_to_use_masked = next_to_use & ring_mask;
 		struct rte_mbuf *mbuf = mbufs[i];
 		struct ena_com_buf ebuf;
 		struct ena_rx_buffer *rx_info;
@@ -1441,7 +1441,7 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 		if (likely((i + 4) < count))
 			rte_prefetch0(mbufs[i + 4]);
 
-		req_id = rxq->empty_rx_reqs[next_to_use_masked];
+		req_id = rxq->empty_rx_reqs[next_to_use];
 		rc = validate_rx_req_id(rxq, req_id);
 		if (unlikely(rc))
 			break;
@@ -1459,7 +1459,7 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 			break;
 		}
 		rx_info->mbuf = mbuf;
-		next_to_use++;
+		next_to_use = ENA_IDX_NEXT_MASKED(next_to_use, rxq->size_mask);
 	}
 
 	if (unlikely(i < count)) {
@@ -2070,7 +2070,6 @@ static struct rte_mbuf *ena_rx_mbuf(struct ena_ring *rx_ring,
 	struct rte_mbuf *mbuf;
 	struct rte_mbuf *mbuf_head;
 	struct ena_rx_buffer *rx_info;
-	unsigned int ring_mask = rx_ring->ring_size - 1;
 	uint16_t ntc, len, req_id, buf = 0;
 
 	if (unlikely(descs == 0))
@@ -2098,8 +2097,8 @@ static struct rte_mbuf *ena_rx_mbuf(struct ena_ring *rx_ring,
 	mbuf_head->data_off += offset;
 
 	rx_info->mbuf = NULL;
-	rx_ring->empty_rx_reqs[ntc & ring_mask] = req_id;
-	++ntc;
+	rx_ring->empty_rx_reqs[ntc] = req_id;
+	ntc = ENA_IDX_NEXT_MASKED(ntc, rx_ring->size_mask);
 
 	while (--descs) {
 		++buf;
@@ -2121,8 +2120,8 @@ static struct rte_mbuf *ena_rx_mbuf(struct ena_ring *rx_ring,
 		mbuf_head->pkt_len += len;
 
 		rx_info->mbuf = NULL;
-		rx_ring->empty_rx_reqs[ntc & ring_mask] = req_id;
-		++ntc;
+		rx_ring->empty_rx_reqs[ntc] = req_id;
+		ntc = ENA_IDX_NEXT_MASKED(ntc, rx_ring->size_mask);
 	}
 
 	*next_to_clean = ntc;
@@ -2134,8 +2133,6 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 				  uint16_t nb_pkts)
 {
 	struct ena_ring *rx_ring = (struct ena_ring *)(rx_queue);
-	unsigned int ring_size = rx_ring->ring_size;
-	unsigned int ring_mask = ring_size - 1;
 	unsigned int free_queue_entries;
 	unsigned int refill_threshold;
 	uint16_t next_to_clean = rx_ring->next_to_clean;
@@ -2152,7 +2149,7 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		return 0;
 	}
 
-	descs_in_use = ring_size -
+	descs_in_use = rx_ring->ring_size -
 		ena_com_free_q_entries(rx_ring->ena_com_io_sq) - 1;
 	nb_pkts = RTE_MIN(descs_in_use, nb_pkts);
 
@@ -2181,9 +2178,10 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 			ena_rx_ctx.pkt_offset);
 		if (unlikely(mbuf == NULL)) {
 			for (i = 0; i < ena_rx_ctx.descs; ++i) {
-				rx_ring->empty_rx_reqs[next_to_clean & ring_mask] =
+				rx_ring->empty_rx_reqs[next_to_clean] =
 					rx_ring->ena_bufs[i].req_id;
-				++next_to_clean;
+				next_to_clean = ENA_IDX_NEXT_MASKED(
+					next_to_clean, rx_ring->size_mask);
 			}
 			break;
 		}
@@ -2208,7 +2206,7 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 
 	free_queue_entries = ena_com_free_q_entries(rx_ring->ena_com_io_sq);
 	refill_threshold =
-		RTE_MIN(ring_size / ENA_REFILL_THRESH_DIVIDER,
+		RTE_MIN(rx_ring->ring_size / ENA_REFILL_THRESH_DIVIDER,
 		(unsigned int)ENA_REFILL_THRESH_PACKET);
 
 	/* Burst refill to save doorbells, memory barriers, const interval */
@@ -2351,8 +2349,6 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	uint16_t next_to_clean = tx_ring->next_to_clean;
 	struct rte_mbuf *mbuf;
 	uint16_t seg_len;
-	unsigned int ring_size = tx_ring->ring_size;
-	unsigned int ring_mask = ring_size - 1;
 	unsigned int cleanup_budget;
 	struct ena_com_tx_ctx ena_tx_ctx;
 	struct ena_tx_buffer *tx_info;
@@ -2382,7 +2378,7 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		if (unlikely(rc))
 			break;
 
-		req_id = tx_ring->empty_tx_reqs[next_to_use & ring_mask];
+		req_id = tx_ring->empty_tx_reqs[next_to_use];
 		tx_info = &tx_ring->tx_buffer_info[req_id];
 		tx_info->mbuf = mbuf;
 		tx_info->num_of_bufs = 0;
@@ -2426,7 +2422,8 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		ena_tx_mbuf_prepare(mbuf, &ena_tx_ctx, tx_ring->offloads,
 			tx_ring->disable_meta_caching);
 
-		rte_prefetch0(tx_pkts[(sent_idx + 4) & ring_mask]);
+		rte_prefetch0(tx_pkts[ENA_IDX_ADD_MASKED(
+			sent_idx, 4, tx_ring->size_mask)]);
 
 		/* Process first segment taking into
 		 * consideration pushed header
@@ -2478,7 +2475,8 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		}
 		tx_info->tx_descs = nb_hw_desc;
 
-		next_to_use++;
+		next_to_use = ENA_IDX_NEXT_MASKED(next_to_use,
+			tx_ring->size_mask);
 		tx_ring->tx_stats.cnt++;
 		tx_ring->tx_stats.bytes += total_length;
 	}
@@ -2509,10 +2507,11 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		tx_info->mbuf = NULL;
 
 		/* Put back descriptor to the ring for reuse */
-		tx_ring->empty_tx_reqs[next_to_clean & ring_mask] = req_id;
-		next_to_clean++;
+		tx_ring->empty_tx_reqs[next_to_clean] = req_id;
+		next_to_clean = ENA_IDX_NEXT_MASKED(next_to_clean,
+			tx_ring->size_mask);
 		cleanup_budget =
-			RTE_MIN(ring_size / ENA_REFILL_THRESH_DIVIDER,
+			RTE_MIN(tx_ring->ring_size / ENA_REFILL_THRESH_DIVIDER,
 			(unsigned int)ENA_REFILL_THRESH_PACKET);
 
 		/* If too many descs to clean, leave it for another run */
diff --git a/drivers/net/ena/ena_ethdev.h b/drivers/net/ena/ena_ethdev.h
index 92d223810c..7dc47c022d 100644
--- a/drivers/net/ena/ena_ethdev.h
+++ b/drivers/net/ena/ena_ethdev.h
@@ -40,6 +40,9 @@
 #define ENA_REFILL_THRESH_DIVIDER      8
 #define ENA_REFILL_THRESH_PACKET       256
 
+#define ENA_IDX_NEXT_MASKED(idx, mask) (((idx) + 1) & (mask))
+#define ENA_IDX_ADD_MASKED(idx, n, mask) (((idx) + (n)) & (mask))
+
 struct ena_adapter;
 
 enum ena_ring_type {
@@ -109,6 +112,7 @@ struct ena_ring {
 	};
 	struct rte_mbuf **rx_refill_buffer;
 	unsigned int ring_size; /* number of tx/rx_buffer_info's entries */
+	unsigned int size_mask;
 
 	struct ena_com_io_cq *ena_com_io_cq;
 	struct ena_com_io_sq *ena_com_io_sq;
-- 
2.25.1

