[PATCH v2] ethdev: account for smaller MTU when setting default

[Joshua Washington <joshwash@google.com>]

Currently, if not specified in the user configuration,
rte_eth_dev_configure() sets the MTU of the device to RTE_EHTER_MTU.
This value could potentially be larger than the MTU that the device
supports. This change updates the configured MTU to be the minimum of
the maximum suported MTU and the default DPDK MTU.

Fixes: 1bb4a528c4 ("ethdev: fix max Rx packet length")
Signed-off-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Rushil Gupta <rushilg@google.com>
---
 lib/ethdev/rte_ethdev.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
index 9163ef47ea..3858983fcc 100644
--- a/lib/ethdev/rte_ethdev.c
+++ b/lib/ethdev/rte_ethdev.c
@@ -1419,7 +1419,9 @@ rte_eth_dev_configure(uint16_t port_id, uint16_t nb_rx_q, uint16_t nb_tx_q,
 	}
 
 	if (dev_conf->rxmode.mtu == 0)
-		dev->data->dev_conf.rxmode.mtu = RTE_ETHER_MTU;
+		dev->data->dev_conf.rxmode.mtu =
+			(dev_info.max_mtu == 0) ? RTE_ETHER_MTU :
+			RTE_MIN(dev_info.max_mtu, RTE_ETHER_MTU);
 
 	ret = eth_dev_validate_mtu(port_id, &dev_info,
 			dev->data->dev_conf.rxmode.mtu);
-- 
2.42.0.869.gea05f2083d-goog