Split the control mode change link logic into a new function:
can_ctrlmode_changelink(). The purpose is to increase code readability
by preventing can_changelink() from becoming too big.

Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
---
 drivers/net/can/dev/netlink.c | 98 ++++++++++++++++++++++++-------------------
 1 file changed, 55 insertions(+), 43 deletions(-)

diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
index 5812114ca8842baedebd698d3000843dbce3ec7d..ab2c9e75347704132b4dfe3b3d29b2c3f1c98908 100644
--- a/drivers/net/can/dev/netlink.c
+++ b/drivers/net/can/dev/netlink.c
@@ -171,6 +171,60 @@ static int can_validate(struct nlattr *tb[], struct nlattr *data[],
 	return 0;
 }
 
+static int can_ctrlmode_changelink(struct net_device *dev,
+				   struct nlattr *data[],
+				   struct netlink_ext_ack *extack)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	struct can_ctrlmode *cm;
+	u32 maskedflags;
+	u32 ctrlstatic;
+
+	if (!data[IFLA_CAN_CTRLMODE])
+		return 0;
+
+	/* Do not allow changing controller mode while running */
+	if (dev->flags & IFF_UP)
+		return -EBUSY;
+
+	cm = nla_data(data[IFLA_CAN_CTRLMODE]);
+	maskedflags = cm->flags & cm->mask;
+	ctrlstatic = can_get_static_ctrlmode(priv);
+
+	/* check whether provided bits are allowed to be passed */
+	if (maskedflags & ~(priv->ctrlmode_supported | ctrlstatic))
+		return -EOPNOTSUPP;
+
+	/* do not check for static fd-non-iso if 'fd' is disabled */
+	if (!(maskedflags & CAN_CTRLMODE_FD))
+		ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;
+
+	/* make sure static options are provided by configuration */
+	if ((maskedflags & ctrlstatic) != ctrlstatic)
+		return -EOPNOTSUPP;
+
+	/* If a top dependency flag is provided, reset all its dependencies */
+	if (cm->mask & CAN_CTRLMODE_FD)
+		priv->ctrlmode &= !CAN_CTRLMODE_FD_TDC_MASK;
+
+	/* clear bits to be modified and copy the flag values */
+	priv->ctrlmode &= ~cm->mask;
+	priv->ctrlmode |= maskedflags;
+
+	/* CAN_CTRLMODE_FD can only be set when driver supports FD */
+	if (priv->ctrlmode & CAN_CTRLMODE_FD) {
+		dev->mtu = CANFD_MTU;
+	} else {
+		dev->mtu = CAN_MTU;
+		memset(&priv->fd.data_bittiming, 0,
+		       sizeof(priv->fd.data_bittiming));
+		priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
+		memset(&priv->fd.tdc, 0, sizeof(priv->fd.tdc));
+	}
+
+	return 0;
+}
+
 static int can_tdc_changelink(struct data_bittiming_params *dbt_params,
 			      const struct nlattr *nla,
 			      struct netlink_ext_ack *extack)
@@ -314,49 +368,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
 	/* We need synchronization with dev->stop() */
 	ASSERT_RTNL();
 
-	if (data[IFLA_CAN_CTRLMODE]) {
-		struct can_ctrlmode *cm;
-		u32 ctrlstatic;
-		u32 maskedflags;
-
-		/* Do not allow changing controller mode while running */
-		if (dev->flags & IFF_UP)
-			return -EBUSY;
-		cm = nla_data(data[IFLA_CAN_CTRLMODE]);
-		ctrlstatic = can_get_static_ctrlmode(priv);
-		maskedflags = cm->flags & cm->mask;
-
-		/* check whether provided bits are allowed to be passed */
-		if (maskedflags & ~(priv->ctrlmode_supported | ctrlstatic))
-			return -EOPNOTSUPP;
-
-		/* do not check for static fd-non-iso if 'fd' is disabled */
-		if (!(maskedflags & CAN_CTRLMODE_FD))
-			ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;
-
-		/* make sure static options are provided by configuration */
-		if ((maskedflags & ctrlstatic) != ctrlstatic)
-			return -EOPNOTSUPP;
-
-		/* If a top dependency flag is provided, reset all its dependencies */
-		if (cm->mask & CAN_CTRLMODE_FD)
-			priv->ctrlmode &= !CAN_CTRLMODE_FD_TDC_MASK;
-
-		/* clear bits to be modified and copy the flag values */
-		priv->ctrlmode &= ~cm->mask;
-		priv->ctrlmode |= maskedflags;
-
-		/* CAN_CTRLMODE_FD can only be set when driver supports FD */
-		if (priv->ctrlmode & CAN_CTRLMODE_FD) {
-			dev->mtu = CANFD_MTU;
-		} else {
-			dev->mtu = CAN_MTU;
-			memset(&priv->fd.data_bittiming, 0,
-			       sizeof(priv->fd.data_bittiming));
-			priv->ctrlmode &= ~CAN_CTRLMODE_FD_TDC_MASK;
-			memset(&priv->fd.tdc, 0, sizeof(priv->fd.tdc));
-		}
-	}
+	can_ctrlmode_changelink(dev, data, extack);
 
 	if (data[IFLA_CAN_BITTIMING]) {
 		struct can_bittiming bt;

-- 
2.49.1