net: don't abuse "default" case for unknown ioctl in dev_ifsioc()

The "switch (cmd)" block from dev_ifsioc() gained a bit too much
unnecessary manual handling of "cmd" in the "default" case, starting
with the private ioctls.

Clean that up by using the "ellipsis" gcc extension, adding separate
cases for the rest of the ioctls, and letting the default case only
return -EINVAL.
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dev_ioctl.c

@@ -391,36 +391,32 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
 		rtnl_lock();
 		return err;
 
+	case SIOCDEVPRIVATE ... SIOCDEVPRIVATE + 15:
+		return dev_siocdevprivate(dev, ifr, data, cmd);
+
 	case SIOCSHWTSTAMP:
 		err = net_hwtstamp_validate(ifr);
 		if (err)
 			return err;
 		fallthrough;
 
-	/*
-	 *	Unknown or private ioctl
-	 */
-	default:
-		if (cmd >= SIOCDEVPRIVATE &&
-		    cmd <= SIOCDEVPRIVATE + 15)
-			return dev_siocdevprivate(dev, ifr, data, cmd);
+	case SIOCGHWTSTAMP:
+	case SIOCGMIIPHY:
+	case SIOCGMIIREG:
+	case SIOCSMIIREG:
+		return dev_eth_ioctl(dev, ifr, cmd);
 
-		if (cmd == SIOCGMIIPHY ||
-		    cmd == SIOCGMIIREG ||
-		    cmd == SIOCSMIIREG ||
-		    cmd == SIOCSHWTSTAMP ||
-		    cmd == SIOCGHWTSTAMP) {
-			err = dev_eth_ioctl(dev, ifr, cmd);
-		} else if (cmd == SIOCBONDENSLAVE ||
-		    cmd == SIOCBONDRELEASE ||
-		    cmd == SIOCBONDSETHWADDR ||
-		    cmd == SIOCBONDSLAVEINFOQUERY ||
-		    cmd == SIOCBONDINFOQUERY ||
-		    cmd == SIOCBONDCHANGEACTIVE) {
-			err = dev_siocbond(dev, ifr, cmd);
-		} else
-			err = -EINVAL;
+	case SIOCBONDENSLAVE:
+	case SIOCBONDRELEASE:
+	case SIOCBONDSETHWADDR:
+	case SIOCBONDSLAVEINFOQUERY:
+	case SIOCBONDINFOQUERY:
+	case SIOCBONDCHANGEACTIVE:
+		return dev_siocbond(dev, ifr, cmd);
 
+	/* Unknown ioctl */
+	default:
+		err = -EINVAL;
 	}
 	return err;
 }