can: treewide: remove can_change_mtu()

can_change_mtu() became obsolete by commit 23049938605b ("can: populate the
minimum and maximum MTU values"). Now that net_device->min_mtu and
net_device->max_mtu are populated, all the checks are already done by
dev_validate_mtu() in net/core/dev.c.

Remove the net_device_ops->ndo_change_mtu() callback of all the physical
interfaces, then remove can_change_mtu(). Only keep the vcan_change_mtu()
and vxcan_change_mtu() because the virtual interfaces use their own
different MTU logic.

The only functional change this patch introduces is that now the user will
be able to change the MTU even if the interface is up. This does not matter
for Classical CAN and CAN FD because their MTU range is composed of only
one value, respectively CAN_MTU and CANFD_MTU. For the upcoming CAN XL, the
MTU will be configurable within the CANXL_MIN_MTU to CANXL_MAX_MTU range at
any time, even if the interface is up. This is consistent with the other
net protocols and does not contradict ISO 11898-1:2024 as having a
modifiable MTU is a kernel extension.

Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20251003-remove-can_change_mtu-v1-1-337f8bc21181@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 0 insertions, 38 deletions

diff --git a/drivers/net/can/dev/dev.c b/drivers/net/can/dev/dev.c
index 15ccedbb3f8d..0cc3d008adb3 100644
--- a/drivers/net/can/dev/dev.c
+++ b/drivers/net/can/dev/dev.c
@@ -359,44 +359,6 @@ void can_set_default_mtu(struct net_device *dev)
 	}
 }
 
-/* changing MTU and control mode for CAN/CANFD devices */
-int can_change_mtu(struct net_device *dev, int new_mtu)
-{
-	struct can_priv *priv = netdev_priv(dev);
-	u32 ctrlmode_static = can_get_static_ctrlmode(priv);
-
-	/* Do not allow changing the MTU while running */
-	if (dev->flags & IFF_UP)
-		return -EBUSY;
-
-	/* allow change of MTU according to the CANFD ability of the device */
-	switch (new_mtu) {
-	case CAN_MTU:
-		/* 'CANFD-only' controllers can not switch to CAN_MTU */
-		if (ctrlmode_static & CAN_CTRLMODE_FD)
-			return -EINVAL;
-
-		priv->ctrlmode &= ~CAN_CTRLMODE_FD;
-		break;
-
-	case CANFD_MTU:
-		/* check for potential CANFD ability */
-		if (!(priv->ctrlmode_supported & CAN_CTRLMODE_FD) &&
-		    !(ctrlmode_static & CAN_CTRLMODE_FD))
-			return -EINVAL;
-
-		priv->ctrlmode |= CAN_CTRLMODE_FD;
-		break;
-
-	default:
-		return -EINVAL;
-	}
-
-	WRITE_ONCE(dev->mtu, new_mtu);
-	return 0;
-}
-EXPORT_SYMBOL_GPL(can_change_mtu);
-
 /* helper to define static CAN controller features at device creation time */
 int can_set_static_ctrlmode(struct net_device *dev, u32 static_mode)
 {