[PATCH v5] net/bonding: call Tx prepare before Tx burst

[Chengwen Feng <fengchengwen@huawei.com>]

Normally, to use the HW offloads capability (e.g. checksum and TSO) in
the Tx direction, the application needs to call rte_eth_tx_prepare() to
do some adjustment with the packets before sending them. But the
tx_prepare callback of the bonding driver is not implemented. Therefore,
the sent packets may have errors (e.g. checksum errors).

However, it is difficult to design the tx_prepare callback for bonding
driver. Because when a bonded device sends packets, the bonded device
allocates the packets to different slave devices based on the real-time
link status and bonding mode. That is, it is very difficult for the
bonded device to determine which slave device's prepare function should
be invoked.

So in this patch, the tx_prepare callback of bonding driver is not
implemented. Instead, the rte_eth_tx_prepare() will be called before
rte_eth_tx_burst(). In this way, all tx_offloads can be processed
correctly for all NIC devices.

Note: because it is rara that bond different PMDs together, so just
call tx-prepare once in broadcast bonding mode.

Also the following description was added to the rte_eth_tx_burst()
function:
"@note This function must not modify mbufs (including packets data)
unless the refcnt is 1. The exception is the bonding PMD, which does not
have tx-prepare function, in this case, mbufs maybe modified."

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Reviewed-by: Min Hu (Connor) <humin29@huawei.com>

---
v5: address Chas's comments.
v4: address Chas and Konstantin's comments.
v3: support tx-prepare when Tx internal generate mbufs.
v2: support tx-prepare enable flag and fail stats.

---
 drivers/net/bonding/rte_eth_bond_8023ad.c | 10 ++++--
 drivers/net/bonding/rte_eth_bond_pmd.c    | 37 ++++++++++++++++++-----
 lib/ethdev/rte_ethdev.h                   |  4 +++
 3 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/drivers/net/bonding/rte_eth_bond_8023ad.c b/drivers/net/bonding/rte_eth_bond_8023ad.c
index b3cddd8a20..29a71ae0bf 100644
--- a/drivers/net/bonding/rte_eth_bond_8023ad.c
+++ b/drivers/net/bonding/rte_eth_bond_8023ad.c
@@ -636,9 +636,12 @@ tx_machine(struct bond_dev_private *internals, uint16_t slave_id)
 			return;
 		}
 	} else {
-		uint16_t pkts_sent = rte_eth_tx_burst(slave_id,
+		uint16_t pkts_sent = rte_eth_tx_prepare(slave_id,
 				internals->mode4.dedicated_queues.tx_qid,
 				&lacp_pkt, 1);
+		pkts_sent = rte_eth_tx_burst(slave_id,
+				internals->mode4.dedicated_queues.tx_qid,
+				&lacp_pkt, pkts_sent);
 		if (pkts_sent != 1) {
 			rte_pktmbuf_free(lacp_pkt);
 			set_warning_flags(port, WRN_TX_QUEUE_FULL);
@@ -1371,9 +1374,12 @@ bond_mode_8023ad_handle_slow_pkt(struct bond_dev_private *internals,
 			}
 		} else {
 			/* Send packet directly to the slow queue */
-			uint16_t tx_count = rte_eth_tx_burst(slave_id,
+			uint16_t tx_count = rte_eth_tx_prepare(slave_id,
 					internals->mode4.dedicated_queues.tx_qid,
 					&pkt, 1);
+			tx_count = rte_eth_tx_burst(slave_id,
+					internals->mode4.dedicated_queues.tx_qid,
+					&pkt, tx_count);
 			if (tx_count != 1) {
 				/* reset timer */
 				port->rx_marker_timer = 0;
diff --git a/drivers/net/bonding/rte_eth_bond_pmd.c b/drivers/net/bonding/rte_eth_bond_pmd.c
index 4081b21338..a2c68ec9bc 100644
--- a/drivers/net/bonding/rte_eth_bond_pmd.c
+++ b/drivers/net/bonding/rte_eth_bond_pmd.c
@@ -602,8 +602,11 @@ bond_ethdev_tx_burst_round_robin(void *queue, struct rte_mbuf **bufs,
 	/* Send packet burst on each slave device */
 	for (i = 0; i < num_of_slaves; i++) {
 		if (slave_nb_pkts[i] > 0) {
+			num_tx_slave = rte_eth_tx_prepare(slaves[i],
+					bd_tx_q->queue_id, slave_bufs[i],
+					slave_nb_pkts[i]);
 			num_tx_slave = rte_eth_tx_burst(slaves[i], bd_tx_q->queue_id,
-					slave_bufs[i], slave_nb_pkts[i]);
+					slave_bufs[i], num_tx_slave);
 
 			/* if tx burst fails move packets to end of bufs */
 			if (unlikely(num_tx_slave < slave_nb_pkts[i])) {
@@ -628,6 +631,7 @@ bond_ethdev_tx_burst_active_backup(void *queue,
 {
 	struct bond_dev_private *internals;
 	struct bond_tx_queue *bd_tx_q;
+	uint16_t nb_prep_pkts;
 
 	bd_tx_q = (struct bond_tx_queue *)queue;
 	internals = bd_tx_q->dev_private;
@@ -635,8 +639,11 @@ bond_ethdev_tx_burst_active_backup(void *queue,
 	if (internals->active_slave_count < 1)
 		return 0;
 
+	nb_prep_pkts = rte_eth_tx_prepare(internals->current_primary_port,
+				bd_tx_q->queue_id, bufs, nb_pkts);
+
 	return rte_eth_tx_burst(internals->current_primary_port, bd_tx_q->queue_id,
-			bufs, nb_pkts);
+			bufs, nb_prep_pkts);
 }
 
 static inline uint16_t
@@ -910,7 +917,7 @@ bond_ethdev_tx_burst_tlb(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 
 	struct rte_eth_dev *primary_port =
 			&rte_eth_devices[internals->primary_port];
-	uint16_t num_tx_total = 0;
+	uint16_t num_tx_total = 0, num_tx_prep;
 	uint16_t i, j;
 
 	uint16_t num_of_slaves = internals->active_slave_count;
@@ -951,8 +958,10 @@ bond_ethdev_tx_burst_tlb(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 #endif
 		}
 
-		num_tx_total += rte_eth_tx_burst(slaves[i], bd_tx_q->queue_id,
+		num_tx_prep = rte_eth_tx_prepare(slaves[i], bd_tx_q->queue_id,
 				bufs + num_tx_total, nb_pkts - num_tx_total);
+		num_tx_total += rte_eth_tx_burst(slaves[i], bd_tx_q->queue_id,
+				bufs + num_tx_total, num_tx_prep);
 
 		if (num_tx_total == nb_pkts)
 			break;
@@ -1064,8 +1073,10 @@ bond_ethdev_tx_burst_alb(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 	/* Send ARP packets on proper slaves */
 	for (i = 0; i < RTE_MAX_ETHPORTS; i++) {
 		if (slave_bufs_pkts[i] > 0) {
-			num_send = rte_eth_tx_burst(i, bd_tx_q->queue_id,
+			num_send = rte_eth_tx_prepare(i, bd_tx_q->queue_id,
 					slave_bufs[i], slave_bufs_pkts[i]);
+			num_send = rte_eth_tx_burst(i, bd_tx_q->queue_id,
+					slave_bufs[i], num_send);
 			for (j = 0; j < slave_bufs_pkts[i] - num_send; j++) {
 				bufs[nb_pkts - 1 - num_not_send - j] =
 						slave_bufs[i][nb_pkts - 1 - j];
@@ -1088,8 +1099,10 @@ bond_ethdev_tx_burst_alb(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 	/* Send update packets on proper slaves */
 	for (i = 0; i < RTE_MAX_ETHPORTS; i++) {
 		if (update_bufs_pkts[i] > 0) {
+			num_send = rte_eth_tx_prepare(i, bd_tx_q->queue_id,
+					update_bufs[i], update_bufs_pkts[i]);
 			num_send = rte_eth_tx_burst(i, bd_tx_q->queue_id, update_bufs[i],
-					update_bufs_pkts[i]);
+					num_send);
 			for (j = num_send; j < update_bufs_pkts[i]; j++) {
 				rte_pktmbuf_free(update_bufs[i][j]);
 			}
@@ -1158,9 +1171,12 @@ tx_burst_balance(void *queue, struct rte_mbuf **bufs, uint16_t nb_bufs,
 		if (slave_nb_bufs[i] == 0)
 			continue;
 
-		slave_tx_count = rte_eth_tx_burst(slave_port_ids[i],
+		slave_tx_count = rte_eth_tx_prepare(slave_port_ids[i],
 				bd_tx_q->queue_id, slave_bufs[i],
 				slave_nb_bufs[i]);
+		slave_tx_count = rte_eth_tx_burst(slave_port_ids[i],
+				bd_tx_q->queue_id, slave_bufs[i],
+				slave_tx_count);
 
 		total_tx_count += slave_tx_count;
 
@@ -1243,8 +1259,10 @@ tx_burst_8023ad(void *queue, struct rte_mbuf **bufs, uint16_t nb_bufs,
 
 		if (rte_ring_dequeue(port->tx_ring,
 				     (void **)&ctrl_pkt) != -ENOENT) {
-			slave_tx_count = rte_eth_tx_burst(slave_port_ids[i],
+			slave_tx_count = rte_eth_tx_prepare(slave_port_ids[i],
 					bd_tx_q->queue_id, &ctrl_pkt, 1);
+			slave_tx_count = rte_eth_tx_burst(slave_port_ids[i],
+					bd_tx_q->queue_id, &ctrl_pkt, slave_tx_count);
 			/*
 			 * re-enqueue LAG control plane packets to buffering
 			 * ring if transmission fails so the packet isn't lost.
@@ -1316,6 +1334,9 @@ bond_ethdev_tx_burst_broadcast(void *queue, struct rte_mbuf **bufs,
 	if (num_of_slaves < 1)
 		return 0;
 
+	/* It is rare that bond different PMDs together, so just call tx-prepare once */
+	nb_pkts = rte_eth_tx_prepare(slaves[0], bd_tx_q->queue_id, bufs, nb_pkts);
+
 	/* Increment reference count on mbufs */
 	for (i = 0; i < nb_pkts; i++)
 		rte_pktmbuf_refcnt_update(bufs[i], num_of_slaves - 1);
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index d43a638aff..e92139f105 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -6095,6 +6095,10 @@ uint16_t rte_eth_call_tx_callbacks(uint16_t port_id, uint16_t queue_id,
  * @see rte_eth_tx_prepare to perform some prior checks or adjustments
  * for offloads.
  *
+ * @note This function must not modify mbufs (including packets data) unless
+ * the refcnt is 1. The exception is the bonding PMD, which does not have
+ * tx-prepare function, in this case, mbufs maybe modified.
+ *
  * @param port_id
  *   The port identifier of the Ethernet device.
  * @param queue_id
-- 
2.17.1