patch 'examples/dma: fix MTU configuration' has been queued to stable release 21.11.2

[Kevin Traynor]

Hi,

FYI, your patch has been queued to stable release 21.11.2

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 06/13/22. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable/commit/d6c4c6477678456f878fa6b1d5aa69de60362f82

Thanks.

Kevin

---
>From d6c4c6477678456f878fa6b1d5aa69de60362f82 Mon Sep 17 00:00:00 2001
From: Huisong Li <lihuisong at huawei.com>
Date: Sun, 24 Apr 2022 14:07:39 +0800
Subject: [PATCH] examples/dma: fix MTU configuration

[ upstream commit e0e95de2be21f05b0a7beb0e63ef969337b60a40 ]

The MTU in dma App can be configured by 'max_frame_size' parameters which
have a default value(1518). It's not reasonable to use it directly as MTU.
This patch fix it.

Fixes: 1bb4a528c41f ("ethdev: fix max Rx packet length")

Signed-off-by: Huisong Li <lihuisong at huawei.com>
---
 examples/dma/dmafwd.c | 43 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/examples/dma/dmafwd.c b/examples/dma/dmafwd.c
index 608487e35c..a03ca05129 100644
--- a/examples/dma/dmafwd.c
+++ b/examples/dma/dmafwd.c
@@ -118,5 +118,5 @@ static volatile bool force_quit;
 
 static uint32_t dma_batch_sz = MAX_PKT_BURST;
-static uint32_t max_frame_size = RTE_ETHER_MAX_LEN;
+static uint32_t max_frame_size;
 
 /* ethernet addresses of ports */
@@ -852,4 +852,36 @@ assign_rings(void)
 /* >8 End of assigning ring structures for packet exchanging. */
 
+static uint32_t
+eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu)
+{
+	uint32_t overhead_len;
+
+	if (max_mtu != UINT16_MAX && max_rx_pktlen > max_mtu)
+		overhead_len = max_rx_pktlen - max_mtu;
+	else
+		overhead_len = RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN;
+
+	return overhead_len;
+}
+
+static int
+config_port_max_pkt_len(struct rte_eth_conf *conf,
+		struct rte_eth_dev_info *dev_info)
+{
+	uint32_t overhead_len;
+
+	if (max_frame_size == 0)
+		return 0;
+
+	if (max_frame_size < RTE_ETHER_MIN_LEN)
+		return -1;
+
+	overhead_len = eth_dev_get_overhead_len(dev_info->max_rx_pktlen,
+			dev_info->max_mtu);
+	conf->rxmode.mtu = max_frame_size - overhead_len;
+
+	return 0;
+}
+
 /*
  * Initializes a given port using global settings and with the RX buffers
@@ -879,7 +911,4 @@ port_init(uint16_t portid, struct rte_mempool *mbuf_pool, uint16_t nb_queues)
 	int ret, i;
 
-	if (max_frame_size > local_port_conf.rxmode.mtu)
-		local_port_conf.rxmode.mtu = max_frame_size;
-
 	/* Skip ports that are not enabled */
 	if ((dma_enabled_port_mask & (1 << portid)) == 0) {
@@ -896,4 +925,10 @@ port_init(uint16_t portid, struct rte_mempool *mbuf_pool, uint16_t nb_queues)
 			rte_strerror(-ret), portid);
 
+	ret = config_port_max_pkt_len(&local_port_conf, &dev_info);
+	if (ret != 0)
+		rte_exit(EXIT_FAILURE,
+			"Invalid max frame size: %u (port %u)\n",
+			max_frame_size, portid);
+
 	local_port_conf.rx_adv_conf.rss_conf.rss_hf &=
 		dev_info.flow_type_rss_offloads;
-- 
2.34.3

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2022-06-09 12:34:31.358342128 +0100
+++ 0070-examples-dma-fix-MTU-configuration.patch	2022-06-09 12:34:29.811980753 +0100
@@ -1 +1 @@
-From e0e95de2be21f05b0a7beb0e63ef969337b60a40 Mon Sep 17 00:00:00 2001
+From d6c4c6477678456f878fa6b1d5aa69de60362f82 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit e0e95de2be21f05b0a7beb0e63ef969337b60a40 ]
+
@@ -11 +12,0 @@
-Cc: stable at dpdk.org