[PATCH 2/3] net/qede: fix Rx callback

[Devendra Singh Rawat <dsinghrawat@marvell.com>]

qede_alloc_rx_bulk_mbufs was trimming the no. of requested mbufs count
to QEDE_MAX_BULK_ALLOC_COUNT. The RX callback was ignorant of this
trimming and it was always resetting the no. of empty RX BD ring
slots to 0. This resulted in RX BD ring getting into an inconsistent
state and ultimately the application fails to receive any traffic.

The fix trims the no. of requested mbufs count before making call to
qede_alloc_rx_bulk_mbufs. After qede_alloc_rx_bulk_mbufs returns
successfully, the no. of empty RX BD ring slots are decremented by the
correct count.

Fixes: 8f2312474529 ("net/qede: fix performance bottleneck in Rx path")
Cc: stable@dpdk.org

Signed-off-by: Devendra Singh Rawat <dsinghrawat@marvell.com>
Signed-off-by: Rasesh Mody <rmody@marvell.com>
---
 drivers/net/qede/qede_rxtx.c | 68 ++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 37 deletions(-)

diff --git a/drivers/net/qede/qede_rxtx.c b/drivers/net/qede/qede_rxtx.c
index 0c52568180..02fa1fcaa1 100644
--- a/drivers/net/qede/qede_rxtx.c
+++ b/drivers/net/qede/qede_rxtx.c
@@ -38,48 +38,40 @@ static inline int qede_alloc_rx_buffer(struct qede_rx_queue *rxq)
 
 static inline int qede_alloc_rx_bulk_mbufs(struct qede_rx_queue *rxq, int count)
 {
+	void *obj_p[QEDE_MAX_BULK_ALLOC_COUNT] __rte_cache_aligned;
 	struct rte_mbuf *mbuf = NULL;
 	struct eth_rx_bd *rx_bd;
 	dma_addr_t mapping;
 	int i, ret = 0;
 	uint16_t idx;
-	uint16_t mask = NUM_RX_BDS(rxq);
-
-	if (count > QEDE_MAX_BULK_ALLOC_COUNT)
-		count = QEDE_MAX_BULK_ALLOC_COUNT;
 
 	idx = rxq->sw_rx_prod & NUM_RX_BDS(rxq);
 
-	if (count > mask - idx + 1)
-		count = mask - idx + 1;
-
-	ret = rte_mempool_get_bulk(rxq->mb_pool, (void **)&rxq->sw_rx_ring[idx],
-				   count);
-
+	ret = rte_mempool_get_bulk(rxq->mb_pool, obj_p, count);
 	if (unlikely(ret)) {
 		PMD_RX_LOG(ERR, rxq,
 			   "Failed to allocate %d rx buffers "
 			    "sw_rx_prod %u sw_rx_cons %u mp entries %u free %u",
-			    count,
-			    rxq->sw_rx_prod & NUM_RX_BDS(rxq),
-			    rxq->sw_rx_cons & NUM_RX_BDS(rxq),
+			    count, idx, rxq->sw_rx_cons & NUM_RX_BDS(rxq),
 			    rte_mempool_avail_count(rxq->mb_pool),
 			    rte_mempool_in_use_count(rxq->mb_pool));
 		return -ENOMEM;
 	}
 
 	for (i = 0; i < count; i++) {
-		rte_prefetch0(rxq->sw_rx_ring[(idx + 1) & NUM_RX_BDS(rxq)]);
-		mbuf = rxq->sw_rx_ring[idx & NUM_RX_BDS(rxq)];
+		mbuf = obj_p[i];
+		if (likely(i < count - 1))
+			rte_prefetch0(obj_p[i + 1]);
 
+		idx = rxq->sw_rx_prod & NUM_RX_BDS(rxq);
+		rxq->sw_rx_ring[idx] = mbuf;
 		mapping = rte_mbuf_data_iova_default(mbuf);
 		rx_bd = (struct eth_rx_bd *)
 			ecore_chain_produce(&rxq->rx_bd_ring);
 		rx_bd->addr.hi = rte_cpu_to_le_32(U64_HI(mapping));
 		rx_bd->addr.lo = rte_cpu_to_le_32(U64_LO(mapping));
-		idx++;
+		rxq->sw_rx_prod++;
 	}
-	rxq->sw_rx_prod = idx;
 
 	return 0;
 }
@@ -1544,25 +1536,26 @@ qede_recv_pkts_regular(void *p_rxq, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 	uint8_t bitfield_val;
 #endif
 	uint8_t offset, flags, bd_num;
-
+	uint16_t count = 0;
 
 	/* Allocate buffers that we used in previous loop */
 	if (rxq->rx_alloc_count) {
-		if (unlikely(qede_alloc_rx_bulk_mbufs(rxq,
-			     rxq->rx_alloc_count))) {
+		count = rxq->rx_alloc_count > QEDE_MAX_BULK_ALLOC_COUNT ?
+			QEDE_MAX_BULK_ALLOC_COUNT : rxq->rx_alloc_count;
+
+		if (unlikely(qede_alloc_rx_bulk_mbufs(rxq, count))) {
 			struct rte_eth_dev *dev;
 
 			PMD_RX_LOG(ERR, rxq,
-				   "New buffer allocation failed,"
-				   "dropping incoming packetn");
+				   "New buffers allocation failed,"
+				   "dropping incoming packets\n");
 			dev = &rte_eth_devices[rxq->port_id];
-			dev->data->rx_mbuf_alloc_failed +=
-							rxq->rx_alloc_count;
-			rxq->rx_alloc_errors += rxq->rx_alloc_count;
+			dev->data->rx_mbuf_alloc_failed += count;
+			rxq->rx_alloc_errors += count;
 			return 0;
 		}
 		qede_update_rx_prod(qdev, rxq);
-		rxq->rx_alloc_count = 0;
+		rxq->rx_alloc_count -= count;
 	}
 
 	hw_comp_cons = rte_le_to_cpu_16(*rxq->hw_cons_ptr);
@@ -1731,7 +1724,7 @@ qede_recv_pkts_regular(void *p_rxq, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 	}
 
 	/* Request number of buffers to be allocated in next loop */
-	rxq->rx_alloc_count = rx_alloc_count;
+	rxq->rx_alloc_count += rx_alloc_count;
 
 	rxq->rcv_pkts += rx_pkt;
 	rxq->rx_segs += rx_pkt;
@@ -1771,25 +1764,26 @@ qede_recv_pkts(void *p_rxq, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 	struct qede_agg_info *tpa_info = NULL;
 	uint32_t rss_hash;
 	int rx_alloc_count = 0;
-
+	uint16_t count = 0;
 
 	/* Allocate buffers that we used in previous loop */
 	if (rxq->rx_alloc_count) {
-		if (unlikely(qede_alloc_rx_bulk_mbufs(rxq,
-			     rxq->rx_alloc_count))) {
+		count = rxq->rx_alloc_count > QEDE_MAX_BULK_ALLOC_COUNT ?
+			QEDE_MAX_BULK_ALLOC_COUNT : rxq->rx_alloc_count;
+
+		if (unlikely(qede_alloc_rx_bulk_mbufs(rxq, count))) {
 			struct rte_eth_dev *dev;
 
 			PMD_RX_LOG(ERR, rxq,
-				   "New buffer allocation failed,"
-				   "dropping incoming packetn");
+				   "New buffers allocation failed,"
+				   "dropping incoming packets\n");
 			dev = &rte_eth_devices[rxq->port_id];
-			dev->data->rx_mbuf_alloc_failed +=
-							rxq->rx_alloc_count;
-			rxq->rx_alloc_errors += rxq->rx_alloc_count;
+			dev->data->rx_mbuf_alloc_failed += count;
+			rxq->rx_alloc_errors += count;
 			return 0;
 		}
 		qede_update_rx_prod(qdev, rxq);
-		rxq->rx_alloc_count = 0;
+		rxq->rx_alloc_count -= count;
 	}
 
 	hw_comp_cons = rte_le_to_cpu_16(*rxq->hw_cons_ptr);
@@ -2028,7 +2022,7 @@ qede_recv_pkts(void *p_rxq, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 	}
 
 	/* Request number of buffers to be allocated in next loop */
-	rxq->rx_alloc_count = rx_alloc_count;
+	rxq->rx_alloc_count += rx_alloc_count;
 
 	rxq->rcv_pkts += rx_pkt;
 
-- 
2.18.2