[PATCH net v2] ibmveth: Fix max MTU limit

Thomas Falcon tlfalcon at linux.ibm.com
Fri Jun 19 07:55:53 AEST 2020


The max MTU limit defined for ibmveth is not accounting for
virtual ethernet buffer overhead, which is twenty-two additional
bytes set aside for the ethernet header and eight additional bytes
of an opaque handle reserved for use by the hypervisor. Update the
max MTU to reflect this overhead.

Signed-off-by: Thomas Falcon <tlfalcon at linux.ibm.com>
Fixes: d894be57ca92 ("ethernet: use net core MTU range checking in more drivers")
Fixes: 110447f8269a ("ethernet: fix min/max MTU typos")
---
v2: Include Fixes tags suggested by Jakub Kicisnki
---
 drivers/net/ethernet/ibm/ibmveth.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index 96d36ae5049e..c5c732601e35 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -1715,7 +1715,7 @@ static int ibmveth_probe(struct vio_dev *dev, const struct vio_device_id *id)
 	}
 
 	netdev->min_mtu = IBMVETH_MIN_MTU;
-	netdev->max_mtu = ETH_MAX_MTU;
+	netdev->max_mtu = ETH_MAX_MTU - IBMVETH_BUFF_OH;
 
 	memcpy(netdev->dev_addr, mac_addr_p, ETH_ALEN);
 
-- 
2.26.2



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