[dpdk-dev] [PATCH 1/2] net/ena: use unmasked head/tail values

[Jakub Palider]

The next_to_clean and next_to_use ring pointers sometimes were kept
wrapped around ring size, sometimes used beyond this limit. From now
on we increment them without regard to ring size limits, but when
reading the values they are wrapped accordingly. Moreover unit16_t
are unsed whenever possible.

Signed-off-by: Tal Avraham <talavr at annapurnalabs.com>
Signed-off-by: Jakub Palider <jpa at semihalf.com>
---
 drivers/net/ena/ena_ethdev.c | 77 ++++++++++++++++++++++++++------------------
 drivers/net/ena/ena_ethdev.h | 24 ++------------
 2 files changed, 47 insertions(+), 54 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index 737ae87..adf94f2 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -676,8 +676,7 @@ static void ena_rx_queue_release_bufs(struct ena_ring *ring)
 		if (m)
 			__rte_mbuf_raw_free(m);
 
-		ring->next_to_clean =
-			ENA_CIRC_INC(ring->next_to_clean, 1, ring->ring_size);
+		ring->next_to_clean++;
 	}
 }
 
@@ -692,8 +691,7 @@ static void ena_tx_queue_release_bufs(struct ena_ring *ring)
 		if (tx_buf->mbuf)
 			rte_pktmbuf_free(tx_buf->mbuf);
 
-		ring->next_to_clean =
-			ENA_CIRC_INC(ring->next_to_clean, 1, ring->ring_size);
+		ring->next_to_clean++;
 	}
 }
 
@@ -926,8 +924,8 @@ static int ena_queue_restart(struct ena_ring *ring)
 	if (ring->type == ENA_RING_TYPE_TX)
 		return 0;
 
-	rc = ena_populate_rx_queue(ring, ring->ring_size - 1);
-	if ((unsigned int)rc != ring->ring_size - 1) {
+	rc = ena_populate_rx_queue(ring, ring->ring_size);
+	if ((unsigned int)rc != ring->ring_size) {
 		PMD_INIT_LOG(ERR, "Failed to populate rx ring !\n");
 		return (-1);
 	}
@@ -962,6 +960,13 @@ static int ena_tx_queue_setup(struct rte_eth_dev *dev,
 		return -1;
 	}
 
+	if (!rte_is_power_of_2(nb_desc)) {
+		RTE_LOG(ERR, PMD,
+			"Unsupported size of RX queue: %d is not a power of 2.",
+			nb_desc);
+		return -EINVAL;
+	}
+
 	if (nb_desc > adapter->tx_ring_size) {
 		RTE_LOG(ERR, PMD,
 			"Unsupported size of TX queue (max size: %d)\n",
@@ -1056,6 +1061,13 @@ static int ena_rx_queue_setup(struct rte_eth_dev *dev,
 		return -1;
 	}
 
+	if (!rte_is_power_of_2(nb_desc)) {
+		RTE_LOG(ERR, PMD,
+			"Unsupported size of TX queue: %d is not a power of 2.",
+			nb_desc);
+		return -EINVAL;
+	}
+
 	if (nb_desc > adapter->rx_ring_size) {
 		RTE_LOG(ERR, PMD,
 			"Unsupported size of RX queue (max size: %d)\n",
@@ -1115,23 +1127,25 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 {
 	unsigned int i;
 	int rc;
-	unsigned int ring_size = rxq->ring_size;
-	unsigned int ring_mask = ring_size - 1;
-	int next_to_use = rxq->next_to_use & ring_mask;
+	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;
 	struct rte_mbuf **mbufs = &rxq->rx_buffer_info[0];
 
 	if (unlikely(!count))
 		return 0;
 
-	ena_assert_msg((((ENA_CIRC_COUNT(rxq->next_to_use, rxq->next_to_clean,
-					 rxq->ring_size)) +
-			 count) < rxq->ring_size), "bad ring state");
+	in_use = rxq->next_to_use - rxq->next_to_clean;
+	ena_assert_msg(((in_use + count) <= ring_size), "bad ring state");
 
-	count = RTE_MIN(count, ring_size - next_to_use);
+	count = RTE_MIN(count,
+			(uint16_t)(ring_size - (next_to_use & ring_mask)));
 
 	/* get resources for incoming packets */
 	rc = rte_mempool_get_bulk(rxq->mb_pool,
-				  (void **)(&mbufs[next_to_use]), count);
+				  (void **)(&mbufs[next_to_use & ring_mask]),
+				  count);
 	if (unlikely(rc < 0)) {
 		rte_atomic64_inc(&rxq->adapter->drv_stats->rx_nombuf);
 		PMD_RX_LOG(DEBUG, "there are no enough free buffers");
@@ -1139,7 +1153,8 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 	}
 
 	for (i = 0; i < count; i++) {
-		struct rte_mbuf *mbuf = mbufs[next_to_use];
+		uint16_t next_to_use_masked = next_to_use & ring_mask;
+		struct rte_mbuf *mbuf = mbufs[next_to_use_masked];
 		struct ena_com_buf ebuf;
 
 		rte_prefetch0(mbufs[((next_to_use + 4) & ring_mask)]);
@@ -1148,12 +1163,12 @@ static int ena_populate_rx_queue(struct ena_ring *rxq, unsigned int count)
 		ebuf.len = mbuf->buf_len - RTE_PKTMBUF_HEADROOM;
 		/* pass resource to device */
 		rc = ena_com_add_single_rx_desc(rxq->ena_com_io_sq,
-						&ebuf, next_to_use);
+						&ebuf, next_to_use_masked);
 		if (unlikely(rc)) {
 			RTE_LOG(WARNING, PMD, "failed adding rx desc\n");
 			break;
 		}
-		next_to_use = ENA_RX_RING_IDX_NEXT(next_to_use, ring_size);
+		next_to_use++;
 	}
 
 	/* When we submitted free recources to device... */
@@ -1475,7 +1490,7 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 	unsigned int ring_size = rx_ring->ring_size;
 	unsigned int ring_mask = ring_size - 1;
 	uint16_t next_to_clean = rx_ring->next_to_clean;
-	int desc_in_use = 0;
+	uint16_t desc_in_use = 0;
 	unsigned int recv_idx = 0;
 	struct rte_mbuf *mbuf = NULL;
 	struct rte_mbuf *mbuf_head = NULL;
@@ -1493,8 +1508,7 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 		return 0;
 	}
 
-	desc_in_use = ENA_CIRC_COUNT(rx_ring->next_to_use,
-				     next_to_clean, ring_size);
+	desc_in_use = rx_ring->next_to_use - next_to_clean;
 	if (unlikely(nb_pkts > desc_in_use))
 		nb_pkts = desc_in_use;
 
@@ -1535,8 +1549,7 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 
 			mbuf_prev = mbuf;
 			segments++;
-			next_to_clean =
-				ENA_RX_RING_IDX_NEXT(next_to_clean, ring_size);
+			next_to_clean++;
 		}
 
 		/* fill mbuf attributes if any */
@@ -1549,10 +1562,10 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
 	}
 
 	/* Burst refill to save doorbells, memory barriers, const interval */
-	if (ring_size - desc_in_use - 1 > ENA_RING_DESCS_RATIO(ring_size))
-		ena_populate_rx_queue(rx_ring, ring_size - desc_in_use - 1);
+	if (ring_size - desc_in_use > ENA_RING_DESCS_RATIO(ring_size))
+		ena_populate_rx_queue(rx_ring, ring_size - desc_in_use);
 
-	rx_ring->next_to_clean = next_to_clean & ring_mask;
+	rx_ring->next_to_clean = next_to_clean;
 
 	return recv_idx;
 }
@@ -1561,7 +1574,8 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 				  uint16_t nb_pkts)
 {
 	struct ena_ring *tx_ring = (struct ena_ring *)(tx_queue);
-	unsigned int next_to_use = tx_ring->next_to_use;
+	uint16_t next_to_use = tx_ring->next_to_use;
+	uint16_t next_to_clean = tx_ring->next_to_clean;
 	struct rte_mbuf *mbuf;
 	unsigned int ring_size = tx_ring->ring_size;
 	unsigned int ring_mask = ring_size - 1;
@@ -1582,7 +1596,7 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	for (sent_idx = 0; sent_idx < nb_pkts; sent_idx++) {
 		mbuf = tx_pkts[sent_idx];
 
-		req_id = tx_ring->empty_tx_reqs[next_to_use];
+		req_id = tx_ring->empty_tx_reqs[next_to_use & ring_mask];
 		tx_info = &tx_ring->tx_buffer_info[req_id];
 		tx_info->mbuf = mbuf;
 		tx_info->num_of_bufs = 0;
@@ -1645,7 +1659,7 @@ 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 = ENA_TX_RING_IDX_NEXT(next_to_use, ring_size);
+		next_to_use++;
 	}
 
 	/* If there are ready packets to be xmitted... */
@@ -1668,10 +1682,8 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 		rte_pktmbuf_free(mbuf);
 
 		/* Put back descriptor to the ring for reuse */
-		tx_ring->empty_tx_reqs[tx_ring->next_to_clean] = req_id;
-		tx_ring->next_to_clean =
-			ENA_TX_RING_IDX_NEXT(tx_ring->next_to_clean,
-					     tx_ring->ring_size);
+		tx_ring->empty_tx_reqs[next_to_clean & ring_mask] = req_id;
+		next_to_clean++;
 
 		/* If too many descs to clean, leave it for another run */
 		if (unlikely(total_tx_descs > ENA_RING_DESCS_RATIO(ring_size)))
@@ -1681,6 +1693,7 @@ static uint16_t eth_ena_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
 	if (total_tx_descs > 0) {
 		/* acknowledge completion of sent packets */
 		ena_com_comp_ack(tx_ring->ena_com_io_sq, total_tx_descs);
+		tx_ring->next_to_clean = next_to_clean;
 	}
 
 	return sent_idx;
diff --git a/drivers/net/ena/ena_ethdev.h b/drivers/net/ena/ena_ethdev.h
index 61390a9..4c7edbb 100644
--- a/drivers/net/ena/ena_ethdev.h
+++ b/drivers/net/ena/ena_ethdev.h
@@ -42,33 +42,13 @@
 #define ENA_MEM_BAR	2
 
 #define ENA_MAX_NUM_QUEUES	128
-
-#define ENA_DEFAULT_TX_SW_DESCS	(1024)
-#define ENA_DEFAULT_TX_HW_DESCS	(1024)
 #define ENA_DEFAULT_RING_SIZE	(1024)
-
 #define ENA_MIN_FRAME_LEN	64
-
-#define ENA_NAME_MAX_LEN     20
-#define ENA_IRQNAME_SIZE     40
-
-#define ENA_PKT_MAX_BUFS     17
+#define ENA_NAME_MAX_LEN	20
+#define ENA_PKT_MAX_BUFS	17
 
 #define ENA_MMIO_DISABLE_REG_READ	BIT(0)
 
-#define	ENA_CIRC_COUNT(head, tail, size)				\
-	(((uint16_t)((uint16_t)(head) - (uint16_t)(tail))) & ((size) - 1))
-
-#define ENA_CIRC_INC(index, step, size)					\
-	((uint16_t)(index) + (uint16_t)(step))
-#define	ENA_CIRC_INC_WRAP(index, step, size)				\
-	(((uint16_t)(index) + (uint16_t)(step))	& ((size) - 1))
-
-#define	ENA_TX_RING_IDX_NEXT(idx, ring_size)				\
-		ENA_CIRC_INC_WRAP(idx, 1, ring_size)
-#define	ENA_RX_RING_IDX_NEXT(idx, ring_size)				\
-		ENA_CIRC_INC_WRAP(idx, 1, ring_size)
-
 struct ena_adapter;
 
 enum ena_ring_type {
-- 
2.5.0