INDIRECT_CALLABLE_SCOPE struct dst_entry *ipv4_dst_check(struct dst_entry *dst,
							 u32 cookie)
{
	struct rtable *rt = (struct rtable *) dst;

	/* All IPV4 dsts are created with ->obsolete set to the value
	 * DST_OBSOLETE_FORCE_CHK which forces validation calls down
	 * into this function always.
	 *
	 * When a PMTU/redirect information update invalidates a route,
	 * this is indicated by setting obsolete to DST_OBSOLETE_KILL or
	 * DST_OBSOLETE_DEAD.
	 */
	if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
		return NULL;
	return dst;
}
INDIRECT_CALLABLE_SCOPE struct dst_entry *ipv4_dst_check(struct dst_entry *dst,
							 u32 cookie)
{
	struct rtable *rt = (struct rtable *) dst;

	 
	if (dst->obsolete != DST_OBSOLETE_FORCE_CHK || rt_is_expired(rt))
		return NULL;
	return dst;
}