
static int __dev_set_allmulti(struct net_device *dev, int inc, bool notify)
{
	unsigned int old_flags = dev->flags, old_gflags = dev->gflags;

	ASSERT_RTNL();

	dev->flags |= IFF_ALLMULTI;
	dev->allmulti += inc;
	if (dev->allmulti == 0) {
		/*
		 * Avoid overflow.
		 * If inc causes overflow, untouch allmulti and return error.
		 */
		if (inc < 0)
			dev->flags &= ~IFF_ALLMULTI;
		else {
			dev->allmulti -= inc;
			pr_warn("%s: allmulti touches roof, set allmulti failed. allmulti feature of device might be broken.\n",
				dev->name);
			return -EOVERFLOW;
		}
	}
	if (dev->flags ^ old_flags) {
		dev_change_rx_flags(dev, IFF_ALLMULTI);
		dev_set_rx_mode(dev);
		if (notify)
			__dev_notify_flags(dev, old_flags,
					   dev->gflags ^ old_gflags);
	}
	return 0;
Unknown