vmxnet3: update MTU after device quiesce

JIRA: https://issues.redhat.com/browse/RHEL-96969

commit 43f0999
Author: Ronak Doshi <ronak.doshi@broadcom.com>
Date:   Thu May 15 19:04:56 2025 +0000

    vmxnet3: update MTU after device quiesce

    Currently, when device mtu is updated, vmxnet3 updates netdev mtu, quiesces
    the device and then reactivates it for the ESXi to know about the new mtu.
    So, technically the OS stack can start using the new mtu before ESXi knows
    about the new mtu.

    This can lead to issues for TSO packets which use mss as per the new mtu
    configured. This patch fixes this issue by moving the mtu write after
    device quiesce.

    Cc: stable@vger.kernel.org
    Fixes: d1a890f ("net: VMware virtual Ethernet NIC driver: vmxnet3")
    Signed-off-by: Ronak Doshi <ronak.doshi@broadcom.com>
    Acked-by: Guolin Yang <guolin.yang@broadcom.com>
    Changes v1-> v2:
      Moved MTU write after destroy of rx rings
    Link: https://patch.msgid.link/20250515190457.8597-1-ronak.doshi@broadcom.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Izabela Bakollari <ibakolla@redhat.com>

Author: Izabela Bakollari

drivers/net/vmxnet3/vmxnet3_drv.c

@@ -3607,8 +3607,6 @@ vmxnet3_change_mtu(struct net_device *netdev, int new_mtu)
 	struct vmxnet3_adapter *adapter = netdev_priv(netdev);
 	int err = 0;
 
-	WRITE_ONCE(netdev->mtu, new_mtu);
-
 	/*
 	 * Reset_work may be in the middle of resetting the device, wait for its
 	 * completion.
@@ -3622,6 +3620,7 @@ vmxnet3_change_mtu(struct net_device *netdev, int new_mtu)
 
 		/* we need to re-create the rx queue based on the new mtu */
 		vmxnet3_rq_destroy_all(adapter);
+		WRITE_ONCE(netdev->mtu, new_mtu);
 		vmxnet3_adjust_rx_ring_size(adapter);
 		err = vmxnet3_rq_create_all(adapter);
 		if (err) {
@@ -3638,6 +3637,8 @@ vmxnet3_change_mtu(struct net_device *netdev, int new_mtu)
 				   "Closing it\n", err);
 			goto out;
 		}
+	} else {
+		WRITE_ONCE(netdev->mtu, new_mtu);
 	}
 
 out: