[dpdk-dev] [PATCH v6 5/6] ethdev: unify MTU checks

[Ferruh Yigit <ferruh.yigit@intel.com>]

Both 'rte_eth_dev_configure()' & 'rte_eth_dev_set_mtu()' sets MTU but
have slightly different checks. Like one checks min MTU against
RTE_ETHER_MIN_MTU and other RTE_ETHER_MIN_LEN.

Checks moved into common function to unify the checks. Also this has
benefit to have common error logs.

Default 'dev_info->min_mtu' (the one set by ethdev if driver doesn't
provide one), changed to ('RTE_ETHER_MIN_LEN' - overhead). Previously it
was 'RTE_ETHER_MIN_MTU' which is min MTU for IPv4 packets. Since the
intention is to provide min MTU corresponding minimum frame size, new
default value suits better.

Suggested-by: Huisong Li <lihuisong@huawei.com>
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
v6:
* Commit log updated to document new default 'dev_info->min_mtu' value
---
 lib/ethdev/rte_ethdev.c | 91 +++++++++++++++++++++++++----------------
 lib/ethdev/rte_ethdev.h |  2 +-
 2 files changed, 57 insertions(+), 36 deletions(-)

diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index ea90bb19680a..2cf50f3abc94 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -1350,6 +1350,47 @@ eth_dev_get_overhead_len(uint32_t max_rx_pktlen, uint16_t max_mtu)
 	return overhead_len;
 }
 
+/* rte_eth_dev_info_get() should be called prior to this function */
+static int
+eth_dev_validate_mtu(uint16_t port_id, struct rte_eth_dev_info *dev_info,
+		uint16_t mtu)
+{
+	uint32_t overhead_len;
+	uint32_t frame_size;
+
+	if (mtu < dev_info->min_mtu) {
+		RTE_ETHDEV_LOG(ERR,
+			"MTU (%u) < device min MTU (%u) for port_id %u\n",
+			mtu, dev_info->min_mtu, port_id);
+		return -EINVAL;
+	}
+	if (mtu > dev_info->max_mtu) {
+		RTE_ETHDEV_LOG(ERR,
+			"MTU (%u) > device max MTU (%u) for port_id %u\n",
+			mtu, dev_info->max_mtu, port_id);
+		return -EINVAL;
+	}
+
+	overhead_len = eth_dev_get_overhead_len(dev_info->max_rx_pktlen,
+			dev_info->max_mtu);
+	frame_size = mtu + overhead_len;
+	if (frame_size < RTE_ETHER_MIN_LEN) {
+		RTE_ETHDEV_LOG(ERR,
+			"Frame size (%u) < min frame size (%u) for port_id %u\n",
+			frame_size, RTE_ETHER_MIN_LEN, port_id);
+		return -EINVAL;
+	}
+
+	if (frame_size > dev_info->max_rx_pktlen) {
+		RTE_ETHDEV_LOG(ERR,
+			"Frame size (%u) > device max frame size (%u) for port_id %u\n",
+			frame_size, dev_info->max_rx_pktlen, port_id);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 int
 rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 		      const struct rte_eth_conf *dev_conf)
@@ -1357,8 +1398,6 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 	struct rte_eth_dev *dev;
 	struct rte_eth_dev_info dev_info;
 	struct rte_eth_conf orig_conf;
-	uint32_t max_rx_pktlen;
-	uint32_t overhead_len;
 	int diag;
 	int ret;
 	uint16_t old_mtu;
@@ -1407,10 +1446,6 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 	if (ret != 0)
 		goto rollback;
 
-	/* Get the real Ethernet overhead length */
-	overhead_len = eth_dev_get_overhead_len(dev_info.max_rx_pktlen,
-			dev_info.max_mtu);
-
 	/* If number of queues specified by application for both Rx and Tx is
 	 * zero, use driver preferred values. This cannot be done individually
 	 * as it is valid for either Tx or Rx (but not both) to be zero.
@@ -1477,26 +1512,13 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 		goto rollback;
 	}
 
-	/*
-	 * Check that the maximum RX packet length is supported by the
-	 * configured device.
-	 */
 	if (dev_conf->rxmode.mtu == 0)
 		dev->data->dev_conf.rxmode.mtu = RTE_ETHER_MTU;
-	max_rx_pktlen = dev->data->dev_conf.rxmode.mtu + overhead_len;
-	if (max_rx_pktlen > dev_info.max_rx_pktlen) {
-		RTE_ETHDEV_LOG(ERR,
-			"Ethdev port_id=%u max_rx_pktlen %u > max valid value %u\n",
-			port_id, max_rx_pktlen, dev_info.max_rx_pktlen);
-		ret = -EINVAL;
-		goto rollback;
-	} else if (max_rx_pktlen < RTE_ETHER_MIN_LEN) {
-		RTE_ETHDEV_LOG(ERR,
-			"Ethdev port_id=%u max_rx_pktlen %u < min valid value %u\n",
-			port_id, max_rx_pktlen, RTE_ETHER_MIN_LEN);
-		ret = -EINVAL;
+
+	ret = eth_dev_validate_mtu(port_id, &dev_info,
+			dev->data->dev_conf.rxmode.mtu);
+	if (ret != 0)
 		goto rollback;
-	}
 
 	dev->data->mtu = dev->data->dev_conf.rxmode.mtu;
 
@@ -1505,6 +1527,12 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 	 * size is supported by the configured device.
 	 */
 	if (dev_conf->rxmode.offloads & DEV_RX_OFFLOAD_TCP_LRO) {
+		uint32_t max_rx_pktlen;
+		uint32_t overhead_len;
+
+		overhead_len = eth_dev_get_overhead_len(dev_info.max_rx_pktlen,
+				dev_info.max_mtu);
+		max_rx_pktlen = dev->data->dev_conf.rxmode.mtu + overhead_len;
 		if (dev_conf->rxmode.max_lro_pkt_size == 0)
 			dev->data->dev_conf.rxmode.max_lro_pkt_size = max_rx_pktlen;
 		ret = eth_dev_check_lro_pkt_size(port_id,
@@ -3417,7 +3445,8 @@ rte_eth_dev_info_get(uint16_t port_id, struct rte_eth_dev_info *dev_info)
 	dev_info->rx_desc_lim = lim;
 	dev_info->tx_desc_lim = lim;
 	dev_info->device = dev->device;
-	dev_info->min_mtu = RTE_ETHER_MIN_MTU;
+	dev_info->min_mtu = RTE_ETHER_MIN_LEN - RTE_ETHER_HDR_LEN -
+		RTE_ETHER_CRC_LEN;
 	dev_info->max_mtu = UINT16_MAX;
 
 	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_infos_get, -ENOTSUP);
@@ -3623,21 +3652,13 @@ rte_eth_dev_set_mtu(uint16_t port_id, uint16_t mtu)
 	 * which relies on dev->dev_ops->dev_infos_get.
 	 */
 	if (*dev->dev_ops->dev_infos_get != NULL) {
-		uint16_t overhead_len;
-		uint32_t frame_size;
-
 		ret = rte_eth_dev_info_get(port_id, &dev_info);
 		if (ret != 0)
 			return ret;
 
-		if (mtu < dev_info.min_mtu || mtu > dev_info.max_mtu)
-			return -EINVAL;
-
-		overhead_len = eth_dev_get_overhead_len(dev_info.max_rx_pktlen,
-				dev_info.max_mtu);
-		frame_size = mtu + overhead_len;
-		if (mtu < RTE_ETHER_MIN_MTU || frame_size > dev_info.max_rx_pktlen)
-			return -EINVAL;
+		ret = eth_dev_validate_mtu(port_id, &dev_info, mtu);
+		if (ret != 0)
+			return ret;
 	}
 
 	ret = (*dev->dev_ops->mtu_set)(dev, mtu);
diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
index 5d64cd6d9504..d7d01d99640c 100644
--- a/lib/ethdev/rte_ethdev.h
+++ b/lib/ethdev/rte_ethdev.h
@@ -3026,7 +3026,7 @@ int rte_eth_macaddr_get(uint16_t port_id, struct rte_ether_addr *mac_addr);
  *  };
  *
  * device = dev->device
- * min_mtu = RTE_ETHER_MIN_MTU
+ * min_mtu = RTE_ETHER_MIN_LEN - RTE_ETHER_HDR_LEN - RTE_ETHER_CRC_LEN
  * max_mtu = UINT16_MAX
  *
  * The following fields will be populated if support for dev_infos_get()
-- 
2.31.1